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Libro de resúmenes
Abstract book
V CURSO
INTERNACIONAL
DE ARTROPLASTIAS
V INTERNATIONAL
COURSE IN
ARTHROPLASTIES
Barcelona, 28 de noviembre - 1 de diciembre 2006
Barcelona, 28 November - 1 December 2006
Dirigido por / Directed by: A. Navarro Quilis (Barcelona)

V CURSO INTERNACIONAL
DE ARTROPLASTIAS
Edita:
Active Congress
Rda. Gral. Mitre, 17, entlo. 4ª
08017 Barcelona
Tel. + 34 93 205 09 71
fax + 34 93 205 38 52
E-mail: info@activecongress.es
Diseño gráfico:
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Imprime:
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Primera edición: noviembre, 2006
Impreso en España

Libro de resúmenes
Abstract book
V CURSO
INTERNACIONAL
DE ARTROPLASTIAS
V INTERNATIONAL
COURSE IN
ARTHROPLASTIES
Dirigido por / Directed by: A. Navarro Quilis (Barcelona)

la organización agradece la colaboración de:

Quiero agradecer a todos los ponentes, en nombre propio y en el
de todos los asistentes al Curso, el esfuerzo que ha supuesto el
enviar los resúmenes para su publicación.
Un libro de resúmenes constituye el mejor recuerdo y, al mismo
tiempo, el mejor elemento de trabajo para el aprovechamiento de
las enseñanzas de tan valiosos expertos.
Aprovecho la ocasión para agradecer el apoyo recibido por la
industria y dejar bien patente que a no ser por su generosidad, ni
este curso ni muchas otras actividades de la educación médica
postgraduada, podrían realizarse.
Antonio Navarro Quilis
Director del Curso
On behalf of the course audience I would like to thank the Faculty
for the effort made sending the abstracts for publication.
The book of abstracts is the final tool for getting the most out of the
course content; as well as being a souvenir of the experience.
I would also like to thank industry for its help, and point out that
without its generosity, this course and many other CME activities
could not be carried out.
Antonio Navarro Quilis
Director of the Course
INTRODUCCIÓN / INTRODUCTION

Índice de ponentes / Speakers index 07
Programa diario / Program
CADERA / HIP
Martes, 28 de noviembre / Tuesday, 28th November 13
Pares de fricción y nuevos materiales /
Friction couple and new materials 14
Fijación de los componentes protésicos /
Fixation of the prosthetic components 74
CADERA / HIP
Miércoles, 29 de noviembre / Wednesday, 29th November 99
Prótesis con conservación ósea: Resurfacing /
Hip prosthesis with bone stock conservation: Resurfacing 100
Abordajes quirúrgicos: MIS y navegación /
Surgical approach: MIS and navigation 124
Cadera difícil y complicaciones de las artroplastias /
Difficult hip and complications 132
Cadera de revisión / Hip revision 148
CADERA / HIP
Jueves, 30 de noviembre / Thursday, 30th November 165
Acetábulo / Acetabulum 166
RODILLA / KNEE
Jueves, 30 de noviembre / Thursday, 30th November 165
Unicompartimentales / Unicompartimentals 188
Prótesis total de rodilla / Total knee arhroplasty 196
RODILLA / KNEE
Viernes, 1 de diciembre / Friday, 1st December 251
Prótesis total de rodilla / Total knee arhroplasty 252
MIS y PTR / TKA and MIS 266
ÍNDICE GENERAL / GENERAL INDEX

ÍNDICE GENERAL / GENERAL INDEX
MIS y navegación / MIS and navigation 274
Complicaciones / Complications 278
Rodilla de revisión / Revision knee 288

ÍNDICE DE PONENTES
SPEAKERS INDEX
V CURSO
INTERNACIONAL
DE ARTROPLASTIAS
V INTERNATIONAL
COURSE IN
ARTHROPLASTIES
ÍNDICE DE PONENTES / SPEAKERS INDEX

ÍNDICE DE PONENTES / SPEAKERS INDEX
ÍNDICE DE PONENTES
SPEAKERS INDEX
P. BEAULÉ
- Patient selection and choice of surgical approach for hip resurfacing. 100
- Femoral head/neck offset and hip resurfacing. 110
- Cause and prevention of femoral neck fracture. 116
- Uses of cages in revision hip surgery. 168
K. BEREND
- Oxford Knee. 190
- Dealing with severe femoral bone loss. 294
- The role of implant constraint. 294
D. BLAHA
- Osseointegration in primary cementless hip fixation. 76
- Femoral component positioning in TKA. A 3-D problem. 220
- Medial pivot knee arthroplasty. 242
P. BONUTTI
- Mobile bearings: are they worth it? 246
- MIS TKA - Selecting the best approach. 266
- Pitfalls and complications of MIS TKA. 270
Ll. CARRERA
- Vástago encerrojado (IRH) en cirugía de revisión 152
A. COSCUJUELA
- Vástago de fijación distal diafisaria en cirugía de revisión. 148
D. DALURY
- Leg lenght discrepancy following THR. 146
- Unicompartimental knee replacement: indications and mistakes. 190
- Mini incision TKR. 272
- The role of computer assisted surgeries. 274
- Diagnosis and management of mid-flexion instability following TKR. 284
- How to reduce wear in TKA? 288
H. DELPORT
- How to cement the femoral head in total hip resurfacing. 114
- PS fixed or mobile?. Does it matter? 246
- MIS knee. A soft tissue operation? 268
D. DENNIS
- Alternative bearing materials: highly cross-linked poly / metal
on metal / ceramic on ceramic. 28
- MIS THA: Posterior Approach. 126
- Evaluation of the painful THA. 138
- Femoral component rotation: How to get it right? 224
- Patellofemoral complications. 254
- Pitfalls of MIS TKA. 268

CH. ENGH
- More than 5 year results in acetabular poly wear and lysis with standard
versus highly linked poly. 68
- Extensively porous coated stems. 78
- Interpreting osteolysis defects. 88
M. FERNÁNDEZ FAIRÉN
- Tantalio ¿material de futuro? 94
W. FITZ
- ConforMIS. Osteotomy, Uni or interposition? 192
- Navigation and MIS, How much does it help? 274
X. FLORES
- PTR séptica. 298
M. FREEMAN
- Special Lecture: In honour of Prof. F. Gomar: How the knee functions. 196
J. GALANTE
- Long-term failure mechanisms in cementless acetabular replacement. 90
- ¿MIS, quo vadis? 124
R. GANZ
- Special Lecture: Origin of osteoarthritis of the hip. 72
- Management of the painful hip of the young adult. 132
- Revision surgery for bone mega-deficiencies including nonunions of the acetabulum. 182
E. GARCÍA CIMBRELOS
- Cotilos roscados, ¿cuándo? 82
R. GEESINK
- Cement or cementless fixation? 74
- Basic science of HA coatings. 90
- Prevention and treatment of recurrent dislocation in THA. 136
- Diagnosis of the painful cementless hip. 146
- Longterm results HA coating in revision THA. 150
J. GIL
- Los plásticos y los pares de fricción. 14
V.M. GOLDBERG
- Clinical results and histological findings of a low-modulus composite stem. 80
- Results of surface replacement multi-center trials: strategies to prevent failure
and minimize the “learning curve”. 116
- Evolution of the cruciate retaining TKA. 222
D. GRIFFIN
- Hip arthroscopy for impingement. 132
- MIS in TKR. 270
R. “DICKEY” JONES
- TKA Hyperflex. 224
ÍNDICE DE PONENTES / SPEAKERS INDEX

ÍNDICE DE PONENTES / SPEAKERS INDEX
- Rotating platform - design and rationale. 244
- Arthroscopic patelloplasty. 252
- Evaluation and treatment of the painful TKA with complex
regional pain syndrome and arthrofibrosis. 284
- Management of periprosthetic fractures in TKA. 292
- Diagnosis and management of infected TKA. 298
L. LÓPEZ-DURÁN
- De Uni a PTR. 288
R. LÓPEZ
- Hidroxiapatita modular. 90
P. MCLARDY-SMITH
- Metal-on-Metal resurfacing of the hip. 120
- The diagnosis and management of peri-prosthetic infections. 184
- The Oxford Experience of Unicompartmental Arthroplasty. 188
M. MENGE
- MIS and Hip Resurfacing. 130
C. MESTRE
- Fracturas periprotésicas. 162
A. MURCIA
- Tantalio en cirugía de revisión. 174
A. NAVARRO
- Hidroxiapatita modular. 90
- Vástago encerrojado (IRH) en cirugía de revisión. 152
T. PAAVILAINEN
- Arthroplasties in dysplasic hips. 134
W. PAPROSKY
- Extensively porous coated stems: our gold standard. 78
- When fully porous coated stems do not work. 150
- Preoperative evaluation of the bone loss. 166
- Constrained liners in revision THA. 168
- Rings, things and cages. 172
J. RICHARDSON
- Metal-Metal couple. Scientific bases. 68
J. ROMERO
- The impact of ligament balancing in total knee arthroplasty. 234
- Evaluation of the painful TKA. 278
- Femorotibial instability after total knee arthroplasty. 286
C. RORABECK
- Metal-Metal bearing surfaces - The way of the future? 70
- Cementless THA in patients less than 50 - Long term results. 80
- Hydroxyapatite on the stem in primary THA - Does it help? 92

- Resurfacing THA - An emerging technology. 106
- The role of bonegrafting in acetabular osteolysis. 166
- UNI TKA - Long term follow up. 188
- The role of stems in revision TKA. 296
K. SOBALLE
- Total hip replacement in congenital dislocated hips. 134
- Revision of the femoral component using extended trochanteric osteotomy. 150
K. STEINBRINK
- Resurfacing Uni. 192
- The advantage of constraint in revision surgery. 294
- The one-stage procedure in septic revision 30 years of experience. 312
D. STULBERG
- The rationale, surgical technique and results of using short, metaphyseal
stems in THA. Short stems - the next generation of implants in THA. 124
- The role of computer assisted surgery in training surgeons to perform TKA. D. 220
- Sources of errors in total knee arthroplasty: the importance of careful,
accurate intra-operative measuerement. 222
- Factors influencing range of motion in TKA. The relationship of accurate implant
alignment and range of motion in TKA surgery. 224
J. TIMPERLEY
- Role of the cement in the fixation of the prosthetic components. 74
- Cemented cups: results and technique. 82
- Resurfacing versus traditional arthroplasty. 122
- Cement-in-cement revision - decreasing the morbidity of revision surgery. 148
- Impactation graft technique in the femur. 150
- Impaction graft technique in the socket. 172
L. WHITESIDE
- Ligament balancing in the varus knee. 230
- Ligament balancing in the valgus knee. 238
- The unresurfaced patella in total knee replacement. 252
- Bone reconstruction and implant fixation in revision total knee replacement. 288
L. WROBLEWSKI
- Wear of UHMWPE cup in THA: What progress? 66
- Component fixation with cement (44 years of clinical experience). 74
- Controversies: Wear of UHMWPE, endosteal cavitation and component loosening -
mechanical or biological? 86
- Septic revision, one or two stages? 184
ÍNDICE DE PONENTES / SPEAKERS INDEX

Notas / Notes
Martes, 28 de noviembre
Tuesday, 28th November
md
CADERA / HIP
Pares de fricción y nuevos materiales
Fijación de los componentes protésicos
Friction couple and new materials
Fixation of the prosthetic components
Moderadores / Moderators: Víctor M. Goldberg, Eduardo García-Cimbrelos,
James Richardson, Charles Engh
MARTES / TUESDAY
13

MARTES / TUESDAY
14
08.30 - 11.30 h
CADERA / HIP
Pares de fricción y nuevos materiales
Friction couple and new materials
Moderador / Moderator: Víctor M. Goldberg
UNI AND
MULTIDIRECTIONAL
WEAR RESISTANCE OF
DIFFERENT CROSSLINKING
GRADE OF UHMWPE FOR
ARTIFICIAL JOINTS.
V.A.González-Mora, M.Hoffmann,
R.Stroosnijder and F.J.Gil.
Institute for Health and Consumer
Protection. Joint Research Centre.
European Commision. Ispra
CREB. Dept. Ciencia de Materiales e Ingeniería
Metalúrgica. ETSEIB. Universidad
Politécnica de Cataluña. Barcelona, Spain.
The objective of this work was to study the
effect of UHMWPE crosslinking in relation to
its wear performance. UHMWPE with different
treatments have been studied by means
of unidirectional and multidirectional wear
tests. The unidirectional simulates the Knee
Total Replacement and the multidirectional
the Hip Total Replacement movements. .
The samples worn were observed by optical
microscopy and by Scanning electron
microscopy in order to determine the wear
mechanism that can explain the different
results between uni and multidirectional wear
tests used.
Key words: Artifi cial joints, wear, polymeric
biomaterials.
Introduction
When the natural joint has to be replaced with
artifi cial materials, there is a change in the
tribological situation due to the inability of the
actual materials used to produce an artifi cial
permanent lubricating fi lm. Therefore, the
materials used for articulating components in
an artifi cial joint are always subject to wear.
Furthermore, there is no ideal bearing material
that currently fulfi ls all the requirements
of arthroplasty design [1-2]. Importantly
therefore wear has to be minimised to avoid
possible aseptic loosening following osteolysis
due to particle-initiated foreign body
reaction [3-5].
The articulating surfaces of a total joint replacement
are recognised as major sources
of wear debris generation. Other implant surfaces,
specifi cally the fi xation surfaces, may
release additional wear debris during in vivo
function. Thus, the origin of wear particles
can be divided into the prosthesis-bone interface
and the prosthesis-prosthesis interface,
which can be designed to be articulating or
non-articulating. The amount of wear debris
from the fi rst kind of interface is small. This
may be acceptable, but only if the debris does
not migrate to other interfaces where it could
contribute to third-body wear [6].
The lack of an adequate standard hampers
the comparison of studies done by different
laboratories and the progress on the understanding
of the wear phenomena occurring
in total joint replacements for ranking the
different UHWMWPE studied [7-9]. It is not
enough to revise or improve the existing

Notas / Notes
md
MARTES / TUESDAY
15

MARTES / TUESDAY
16
standards. Furthermore, the necessity is
evident for developing a new standard for
screening wear tests based on the latest
fi ndings, such as multidirectional motion or
lubricant composition
Materials And Methods
A pin-on-disk (POD) wear test machine is a
common wear test method, which has been
widely used to evaluate the wear of polymers
in biotribology. In a POD the polymer, usually
in the form of a pin, slide over the surface of a
rotating disk. Two basic confi gurations can be
distinguished; the pin may be loaded along
its major axis, in a direction either normal to
or parallel with the axis of rotation of the disk.
Hence, the contact area is produced on the
edge (horizontal POD confi guration) or the
face (vertical POD confi guration) of the disk.
According to this defi nition, the wear test
method proposed here was a horizontal POD
(here in after called simply as POD I).
In the POD test device, a wheel or ring in
vertical position wears against an underlying
pin of polyethylene. Figure 1a shows
schematically the loading/motion confi guration.
The contact geometry at the test start
is non-conformal, that is a line-contact. In
this sense, these wear test devices would be
more representative for a knee wear device
than for a hip wear device, where the contact
geometry is conformal (also designated as
congruent).
There is no standard regarding this type
of wear device and similar studies are not
present in the literature. Thus, comparison
and analysis of the test conditions proposed
cannot be made. Due to its confi guration,
the closest available standard would be
the ASTM G137-97, with identical contact
geometry and intended too for ranking the
resistance of plastic materials in sliding wear.
However, this standard does not cover biotribological
conditions.
The multidirectional POD (POD II) wear test
method is based on the former unidirectional
POD (POD I) wear test method. However, in
the POD II test method the pin rotates too,
see Figure 1b, and as consequence of the
rotation of the pin this device has a biaxial
pattern motion (i.e. multidirectional). In the
literature, no wear device similar to this can
be found making from it a unique screening
wear test device. The tasks with this wear
test method are in principle the same as for
the former POD I. With the POD II tests,
additionally the effect of the motion type in
the wear resistance of the UHMWPE can
be studied.
The test with the POD test method was performed
as follows. The disk rotates continuously
against an underlying pin of UHMWPE.
A load of ~150 N (15 Kg) was applied to the
pins. It gives a maximum Herztian contact
pressure (po) of ~5 MPa. The relative surface
velocity was 100 rpm for the disk and
for the multidirectional test, the pin velocity
was 99 rpm. The frequency of the disk was
1 Hz. The wear of the UHMWPE pins was
mainly determined by profi lometric measurements.
Weight loss measurements were also
performed after the completion of the test.
The test length was 34 Km.
To the test lubricant distilled water was
added during the test for compensating
water evaporation. As test lubricant, a solution
consisting of bovine serum and distilled
water was used, which had a total protein
concentration of 30 mg/ml. The serum was
purchased at Sigma-Aldrich SrI (Calf serum,
bovine donor; product No.C9676). The soak
adsorption of the UHMWPE pins was determined
using an additional control pin, which
was loaded identically as the UHMWPE
pins in the RPOF machine, but no motion
was applied. The cleaning and drying of the
UHMWPE pins was performed according
to the ASTM 1715 standard. Weighing was
carried out with a Mettler Toledo AT261DeltaRange
® microbalance with an accuracy
of ±10 μg.

Notas / Notes
md
MARTES / TUESDAY
17

MARTES / TUESDAY
18
Disks were manufactured of forged CoCrMo
alloy (purchased at Firth Rixson Superalloys
Ltd. Derbyshire, England). The dimensions
of the disks were 88 mm in diameter and 10
mm thick. The roughness of the disk was
determined by laser perfi lometer obtained a
value of R a =0.01μm. The pins were manufactured
from UHMWPE GUR1050 bar, with 13
mm length and 9 mm diameter. Four different
treatments on the UHMWPE material were
investigated:
• Non-treated
• Crosslinked I (γ-sterilised + stabilised I)
with the following treatment:
γ (sterilisation) irradiation with 100 KGy of
gamma ray in air, and
γ (stabilisation) McKellop heat treatment:
155 °C for 72 hours in nitrogen.
• Crosslinked II (γ-sterilised + stabilised II)
with the following treatment:
γ (sterilisation) irradiation with 100 KGy of
gamma ray in air, and
γ (stabilisation) heat treatment under water:
130 °C in H 2 O for 72 hours.
• Sterilised with standard, 25 KGy (2.5
Mrad), gamma radiation in air.
For each UHMWPE material 3 samples
were tested. A total of 12 wear tests were
performed. Test conditions and materials
are resumed in ¡Error! No se encuentra el
origen de la referencia..
Experimental results and dicussion.
The wear results, given in volumetric wear
(mm 3 ), are calculated from the average
weight loss (mg) of three specimens per
each UHMWPE material. A higher weight
loss of the UHMWPE material represents
a higher wear of the specimen. A graphical
representation of the wear results is shown
in Figure 2.
Unidirectional Wear Test.
For the unidirectional test, the results show a
higher wear for the irradiated and crosslinked
UHMWPEs (XLPEs) than for the unirradiated
UHMWPE material. The UHMWPE wear
obtained for the irradiated and XLPEs are in
the same order and represent a 1.5 to 1.8fold
increase with respect to the unirradiated
UHMWPE. A high reproducibility of the wear
tests has been achieved, with a low standard
deviation not exceeding in any case 7% in
weight loss of the specimens. The results
shown that the difference between crosslinked
materials is statistically no signifi cant
(p

Notas / Notes
md
MARTES / TUESDAY
19

MARTES / TUESDAY
20
by the machining tool. The main feature are
the scratches that have been caused by the
action of the disc sliding on the pin surface,
leaving a typical unidirectional lay structure,
lined up with the sliding direction of the disc
on the pin surface, see Figure 3c.The wear
zone has a polished appearance to the naked
eye. On the other hand, in the wear zone
(Figure 3c) the continuous sliding of the disc
on the pin surface has caused, besides the
scratches already mentioned, a microstructure
in the form of a ripple-like microstructure
or lay of the fi bres forming the UHMWPE.
The ripples are perpendicular to the sliding
direction. As conclusion, this microstructure
demonstrates an evident alignment of the
UHMWPE fi bres depending on the sliding
direction.
Optical micrographs of the worn surfaces
revealed the ripple-like structure for all the
pins studied (Figure 3d). However, the size of
the ripples was different if the pin was from a
XLPE material (Figure 3e and 3f). The ripplelike
structure is clearly smaller compared to
the microstructure founded for the unirradiated
or irradiated UHMWPE. The ripples on
XLPEs are smaller because their fi bres are
smaller when compared to noncrosslinked
UHMWPEs. This is a consequence of the
heat treatment that XLPEs undergo after
irradiation, for these materials performed at
155°C, which acts as a remelting process
for the UHMWPE fi bres. Other feature on
the worn surfaces are the higher number of
scars for irradiated and XLPEs than for the
unirradiated UHMWPE, and at the scars are
shallower. Both, features, the morphology, the
morphology of the ripples and the scratches,
indicate a lower grade of deformation of the
irradiated and XLPEs, because the crosslinking
induced by irradiation.
The observation by means of SEM was focused
in the formation of UHMWPE particles
that detach from the pin surface producing
wear debris. In the following, the scanning
electron micrographs of the unirradiated
(Figure 3g), irradiated (Figure 3h), XLPE I
(Figure 3i) and XLPE II (Figure 3j) materials
are shown.
From SEM observations, Figures 3g to
3j show that the UHMWPE pins exhibit a
cracked surface texture. This texture is
evidenced as microcracks present in every
direction but preferentially occurring
between ripples, highlighting the ripple-like
microstructure of the UHMWPE seen under
optical microscopy. These microcracks are,
however, an artefact produced bay gold sputtering,
necessary to render conductive the
UHMWPE surface. They do not represent
microcracks in the UHMWPE surface. This
artefact could not be avoided, even with very
short sputtering periods.
Besides the ripple-like microstructure, other
features can be observed, as for example,
the particle formation in the form of fi brils on
the worn surfaces. The study of the particle
formation is an essential point to understand
the wear processes occurring, because it has
been hypothesised that wear particles will be
liberated from the articulating surface after
the cyclic accumulation of a critical amount
of plastic strain.
The grade of fi bril formation is higher for the
unirradiated than for the irradiated material
and then less for the XLPEs. For non-XLPEs,
fi brils are oriented parallel to the sliding direction
and can extend over several ripples.
For XLPEs, more than fi bril formation there
is formation of rounded particles smaller than
those formed for the non-XLPEs. The particle
formation of The XLPEs corroborates again
the lower deformation capacity of the XLPEs
in comparison with irradiated and unirradiated
UHMWPEs. In Figure 3j, the concentration
of plastic strain on the polyethylene surface
on the XLPEs can be observed.
Considering weight loss results, the particle
formation in XLPEs should have been higher
than for the non-XLPEs, since the UHMWPE

Notas / Notes
md
MARTES / TUESDAY
21

MARTES / TUESDAY
22
wear was also higher. At thispoint, it is necessary
to remember the phenomenon of
irrecoverable and permanent strain resulting
from mechanical loading, which is termed
plasticity and that holds clues to the wear and
mechanical loading history of UHMWPE. The
higher wear debris production for the XLPEs
can be explained if particles forming on the
XLPEs detached immediately because they
can bear a lower strain concentration 5,6
than non-XLPEs particles, what coincide
with the appearance of rounded and smaller
XLPE particles. On the other hand, non
XLPEs posses a higher capacity of deforming
(or plasticity), allowing particles to retain
a higher accumulation of plastic strains and
resulting in less particle detachment and consequently
lower weight loss. This coincides
with the known fact that under unidirectional
sliding conditions a molecular orientation of
UHMWPE occurs, including anisotropy in the
UHMWPE and orientation hardening on the
direction of sliding [11]. Concluding, UHM-
WPEs with higher capacity to deform locally
(plasticity) present a higher wear resistance
and lower weight loss under unidirectional
conditions. For the same reasons, unirradiated
UHMWPE wears less than irradiated
as this and other studies have shown, since
the last posses lower plasticity, due to the
sterilisation (irradiation process).
Multidirectional wear test.
The wear results of the UHMWPE specimens
(pins) obtained with the POD II (multidirectional)
test method are shown in Figure 4.
The wear results show a higher wear for
the irradiated and unirradiated UHMWPE
material compared to the XLPEs. That is,
the unirradiated UHMWPE and especially the
irradiated UHMWPE materials perform worse
than the crosslinked materials. In fact, the
irradiated and the unirradiated UHMWPEs
have respectively a 3.5 and 5-fold higher
wear than the XLPE II.On the other hand,
the irradiated material has a 1.43-fold higher
wear than the unirradiated UHMWPE. XLPE
I and II have a similar wear resistance, although
the latter shows a slightly lower wear
than XPLE I, statistically signifi cant (p

Notas / Notes
md
MARTES / TUESDAY
23

MARTES / TUESDAY
24
ments, since the UHMWPE wear can be
significantly reduced with respect to the
standard irradiated (25 kGy) UHMWPE. The
results under unidirectional sliding conditions
show, however, that the XLPEs are subjected
to more wear compared to the unirradiated
UHMWPE. Therefore, in situations where the
unidirectional sliding motion is the main type
of motion between the articulating components,
as encountered in most of the current
Total Knee Replacement designs, XLPEs
should not be used. It is now recognised that
the different kinematics in the hip and knee
can lead to different wear mechanism surface
and wear rate of the UHMWPE component
[12]. For Total Hip Replacements, it is now
widely accepted that wear is related to the
mechanical response of UHMWPE material
under multidirectional conditions. In Total
Hip Replacements the large variation in the
direction of the velocity vector leads to cross
shearing of the strain hardened polyethylene
and accelerates wear. However, for Total
Knee Replacements the major contribution
in sliding motion seems to be unidirectional,
depending on the prosthesis design, and
thus the response of UHMWPE under unidirectional
conditions seems to be the most
important. Retrieved total knee components
present scratches on the UHMWPE component
predominantly parallel to the wear
sliding direction [6-7]. Thus, in the Total Knee
Replacements, with a preferentially unidirectional
motion, the wear may be lower due to
the orientation and strain hardening of the
UHMWPE in the direction of motion. Two factors
must be taken into account, which effect
in the UHMWPE wear behaviour has not still
been totally addressed: the high variability
in knee designs and the much higher stress
contacts than for the hip.
The optical microscopy at low magnifi cation
are presented in Figures 5a to 5d, showing
that the unirradiated and irradiated UHM-
WPEs exhibit a higher wear damage when
compared to XLPEs, in concordance with the
weight loss results. It should be noted that
parallel scratches found on the pin surfaces
in the unidirectional tests (POD I) are not
present here and only multidirectional shallow
scratches are seen.
Optical microscopy images at higher magnifi
cation, on the middle of the pin diameter
were taken; see Figures 5e to 5h. The central
plateau was not considered because the optical
microscope was not able to observe any
feature beside the fl atness of this region. The
fi gures reveal a similar ripple-like microstructure
for all the pins studied. In this case, the
ripples are less aligned than those founded
for the unidirectional wear tests. Again, the
microstructure of the ripples is more evident
in the unirradiated and irradiated UHMWPEs
than in the XLPEs, which reinforces the
theory that the XLPEs have a lower plasticity,
as discussed for the unidirectional wear
results. The ripples are perpendicular to the
sliding direction, which under the multidirectional
sliding condition applied results in a
radial orientation of the ripples as if the sliding
directions were from the centre of the pin to
its border.
The SEM observation was focused in the
formation of UHMWPE particles that detach
from the pin surface producing wear debris.
In the following, the scanning electron micrographs
of the unirradiated (Figure 5i), irradiated
(Figure 5j) XPLE I (Figure 5k), and XLPE
II (Figure 5l) materials are shown.
The ripple-like microstructure already identifi
ed by optical microscopy is present on
the zone outside the central plateau, for
the unirradiated and irradiated UHMWPEs.
The central plateau of the pin shows a very
homogeneous and fl at microstructure, where
no ripples can be identifi ed. However, there
is formation of particles and fi brils in the
central plateau. The formation of fi brils was
also observed on the rest of the worn surface.
All the fi brils are oriented along the sliding
direction and perpendicular to the ripple-like
microstructure (radial from the pin centre to

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the pin border), see Figure 6 and these fi brils
can extend over several ripples. The fi bril
formation is more marked for the unirradiated
than for the irradiated material and then for
the crosslinked materials.
For the XLPEs the homogeneous ripple-like
microstructure can be seen overall the pin
surface. The fi bril formation is less marked
for the XLPEs than for the unirradiated and
irradiated UHMWPEs. Compared to the noncrosslinked
UHMWPEs, XLPEs show much
less particle formation and smaller size of
the fi brils. As for the unidirectional tests, the
fi brils are much likely rounded and smaller
size, which under the SEM appear as white
particles forming on the ripples of the microstructure.
As explained for the unidirectional
wear tests, this particle formation in XLPEs is
caused by their lower plasticity behaviour.
From the size of the fi brils forming on both
non-crosslinked UHMWPEs and XLPEs, the
size of the particles forming the UHMWPE
debris can be estimated. Figures 5i to 5l
and 6 show that the size of the UHMWPE
particles detaching from the worn surfaces
are ranging from submicron to more than
one micron. It has been found that in Total
Hip Replacements the majority of UHMWPE
particles are less than one micron in length
[13]. Studies of wear particles retrieved from
periprosthetic tissues and analyses of worn
polyethylene surfaces have demonstrated
fi ndings that are consistent with an average
particle size in the 0.5 micrometers diameter
range. [3,7].
Test parameter Value
Contact geometry Cylinder-on-fl at (non-conformal)
Frequency 1 Hz
Relative surface velocity 100 rpm
Contact area Line
Load applied ~150 N (15 Kg)
Contact stresses 5 MPa
Test length 34 Km (123,000 disk rotations)
Lubricant 30 mg/ml initial protein content
Temperature Room
Counterface component CoCrMo alloy
UHMWPE component (GUR 1050) Non-treated
Crosslinked I (γ-sterilised + stabilised I)
Crosslinked II (γ-sterilised + stabilised II)
References
1. Miller D.A., Herrington S.M, Higgins J.C.,
Schroeder D.W, “UHMWPE polyethylene
in total joint replacement: History and
current tecnology” in Encyclopaedic Handbook
of biomaterials and bioengineering,
Part B: Applications, Volume 1, (DL.Wise
et alumina; editors), Marcel Dekker, Inc.,
pp. 665-688, 1995.
2. Greer K.W., Hamilton J.V., Cheal E.J.,
“Polyethylene wear in orthopaedics” in
Encyclopaedic Handbook of biomaterials
and bioengineering, Part B: Applications,
Volume 1, (DL.Wise et alumina; editors),
Marcel Dekker, Inc., pp. 613-638, 1995.
3 Murray D., Rushton N., “Macrophages
stimulate bone resorption when they
phagocytose particles”, J. Bone and Joint
Surgery 72-B, 988-992, 1990.
4. Howie D., McGee M., “Wear and osteolysis
in relation to prostheses design and materials”
in Medical applications of Titanium
and its alloys (ASTM STP 1272), 1996.
5. McGee M., Howie D., Neale S., Haynes
D., Pearcy M., “The role of polyethylene
wear in joint replacement failure”, Proc.
Instn. Mech. Engrs. Part H Vol. 211, 65-
72, 1997.
6. Green T., Fisher J., Stone M., Wroblewski
B., Ingham E., “Polyethylene particles of a
‘critical size’ are necessary for the induction
of cytokines by macrophages in vitro”,
Biomaterials 19, 2297-2302, 1998.

Notas / Notes
md
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28
7. Greer K.W., Hamilton J.V., Cheal E.J,
“Polyethylene wear in orthopaedics” in
Encyclopaedic Handbook of biomaterials
and bioengineering, Part B: Applications,
Volume 1, (DL.Wise et alumina; editors),
Marcel Dekker, Inc., pp. 613-638, 1995.
8. Plitz W., Walter A., “Tribological aspects
of metal/polymer couplings”, in Technical
principles, design and safety of joint
implants (G. Buchhorn, H-G. Willert,
eds.), Hogrefe &Huber Publishers, 82-
89, 1994.
9. Algan S.M., Horowitz S.M., “Biology of
aseptic loosening of the cemented arthroplasty”
in Encyclopaedic Handbook
of biomaterials and bioengineering, Part
B: Applications, Volume 1, (DL.Wise et
alumina; editors), Marcel Dekker, Inc., pp.
773-797, 1995.
10. Viceconti M., Cavallotti G., Andrisano A.,
Toni A., “Discussion on the design of a hip
joint simulator”, Med. Eng. Phys. 18, No.3,
234-240, 1996.
11. Ben Abdallah A., Treheux D., “Friction
and wear of ultrahigh molecular weight
polyethylene against various new ceramics”,
Wear 142, 43-56, 1991.
12. Suh N., Mosleh M., Arinez J., “Tribology
of polyethylene homocomposites”, Wear
214, 231-236, 1998.
13. Streicher M., “Tribology of artifi cial joints”,
in “Endoprosthetics” (E. Morscher, editor),
Springer Verlag, 1995.
ALTERNATIVE BEARING
MATERIALS:
HIGHLY CROSS-LINKED
POLY/METAL ON METAL/
CERAMIC ON CERAMIC
D. A. Dennis, M.D.
Adjunct Professor, Dept. of Biomedical
Engineering, University of Tennessee
Assistant Clinical Professor, University
of Colorado Health Sciences Center
Clinical Director, Rocky Mountain Musculoskeletal
Research Laboratory
Denver, Colorado, USA
I. Bearing Surfaces and Wear Particle-Induced
Osteolysis
A.The Problem
- Improved fi xation of implants in the 1980’s
has unmasked another limitation of THA…
wear particle induced osteolysis
“The presence of macrophages at the interface
is a tissue response that no implant
surgeon can lightly dismiss.” 32
- Production of osteolytic mediators and
metabolic byproducts by histiocytes is
stimulated by phagocytosis of particulate
debris. 7,72,86,100,102
• Particulate biomaterials including the
articulating surface, bone cement, and
porous metal fi xation surfaces have all
been implicated. 7,86,124,125,174,175
• Ultra-High Molecular Weight Polyethylene
is now widely perceived as the most
signifi cant particle in wear induced bone
resorption and the ultimate cause of failure
of many implants. 7,86,124,125,174,175
• How much polyethylene wear is too
much?
• Osteolysis is associated with linear wear
rates >0.2mm/year in both cemented
THA 149,218 and cementless THA 208,216
• Minimal osteolysis when linear wear <
0.1mm/year 149,208,216,218

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B. The Solution
- Optimization/Development of Bearing
Surfaces to Reduce Wear 25,83,91,137,169
• Metal on Metal
• Ceramic on Ceramic
• Improved Polyethylene (Highly Cross-
Linked)
II. Metal on Metal Bearing Surface
A.History
• First metal on metal total hip performed by
Philip Wiles in 1938
• Initial thrust of development in England
in 1960’s
• First widely used metal on metal articulation
featured Cobalt-Chromium alloy
against itself (McKee-Farrar, Stanmore,
Muller, Ring and Sivash)
• Metal on metal articulations abandoned
by the early 1970’s secondary to relatively
high short-term clinical failure (early
loosening) and growing success of the
Charnley prosthesis
• Disregarding early failures, long-term survivorship
of the early designs was noted to
be comparable to the Charnley prosthesis
and wear noted to be magnitudes less than
the metal-on-polyethylene designs 98
• Revival and development of second generation
metal-on-metal bearings in the
1980’s as wear and osteolysis became a
foremost concern as complications of total
hip arthroplasty
• Early and mid-term clinical follow-up of
second generation metal on metal implants
comparable to conventional metal
on polyethylene and better than that of fi rst
generation metal on metal THA 52,53
• Biologic response to metal particles/ions
comes under scrutiny
B. Design Issues
• First generation metal on metal articulations
• Early clinical failures secondary to poor
design features
• Equatorial bearing contact 105,205
• Poor surface fi nish and irregular geometry130
• Thin & fl exible metal → bearing lock-up
• Poor stem design → premature loosening128,129,130
• Second generation metal on metal articulations
• Advances in engineering/manufacturing
• Material 26,172
• Cobalt chromium molybdenum favored
• Hardness (> 40 R ) c
• Processing: Cast vs. Forged/High vs.
Low carbon
• Scientifi c data unclear
• Appears no signifi cant effect on wear
with today’s higher-quality initial surface
fi nish and sphericity 26
• Clearance: Desire polar bearing, not
equatorial
- Wear decreases with decreasing diam-
26, 28,29,59,138,139
etral clearance
- Volumetric wear halved by reducing
clearance from 90 to 45 um
- Manufacturing diffi culties controlling
dimensional tolerances below 20 um
- Desired diametral clearance dependent
on femoral head size
· Ideally less than 90 um for 28 mm
femoral head
· Acceptable clearance higher as femoral
head size increases
• Surface Roughness
- Wear decreases with decreasing surface
roughness (linear regression, R2 =
0.91) 28
26, 27
• Fluid Film Lubrication
- Low clearance and low surface roughness…favorable
parameters for fl uid
fi lm lubrication and decreased wear
C. Results
• First generation metal on metal articulations
• Many fi rst generation metal on metal failures
were design related and unassociated with
the metal bearing material itself
• McKee-Farrar

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32
• Short to medium term follow-up (1-10 yrs)
12,14,30,40,43,47,62,63,109,110,113,128,129,143,148,153,159,163,168
,183,201,212
- 0.9-50% aseptic loosening
- 0.9-13.5% revised
• Long term follow-up (10-22 yrs)
- 12.2-22% aseptic loosening 4,10,19,98,99,106,204
- Survivorship @ 10 yrs 79-91% 10,98,204
- Survivorship @ 12-15yrs 72-84% 10,98,204
- Survivorship @ 20yrs 27.5% 10
• Stanmore
• 75.5% survivorship @ 5-6yrs 48
• 53% survivorship @ 11 years 48
• Muller
• 27% revised for aseptic loosening @ 12-
15 years 6
• Ring
• Short to medium term follow-up (1-9 yrs)
5,8,58,113,167,188
- 3-16% aseptic loosening
- 5-18% revised
• Long term follow-up (15-21 yrs)
- 21% aseptic loosening 24
- Survivorship @ 10 yrs 74-95% 24,30
- Survivorship @ 20 yrs 60% 30
• Sivash
• Clinical data scant: never gained popularity
outside USSR
• Second generation metal on metal articulations
• Metasul 2-4 yr follow-up 53
• No revisions for loosening
• No radiographic osteolysis
• Metasul 4-6.8 yr follow-up 52
• One acetabular component revised for
loosening (2%); no femoral loosening
• No radiographic osteolysis
• Metasul 7 yr follow-up
• No loosening
• Limited Osteolysis In 2 of 70 (2.9%) 104
• M2a-Taper: Minimum 2 yr follow-up (avg.
3.2 yr.) 120
• No revisions for loosening
• No radiolucencies > 1mm
• No significant clinical or radiographic
difference between metal on metal and
conventional UHMWPE liner groups
D. Potential Advantages of a Metal on
Metal Bearings
• Extremely low wear 97,176,187
• Linear wear …25X less than conventional
metal on polyethylene articulations
• 1.0-5 um/year (McKee-Farrar) vs. 0.1-0.2
mm/year (Charnley)
• Volumetric wear…20X less than conventional
metal on polyethylene articulation
• 1-5mm 3 /year (metal on metal) vs. 50-
100mm 3 /year (metal on polyethylene)
• Decreased infl ammatory response 80
• “Self healing” capacity (should surface
imperfection develop) 172
• Increased ROM, stability, and wear, with
larger femoral heads 190
• Potential for serum and urine markers of
implant performance 96
• Clinically documented long-term survival
• Reduced aseptic loosening 150
E. Potential Disadvantages of Metal on
Metal Bearings
• Biologic response to metal particles/ions
• ? Carcinogenesis
• First documented case of cancer after
THA- MFH in patient 3.5 years after
McKee-Farrar THA 196
• 24 additional cases of malignant disease
occurring in association with THA or TKA
in the English-language literature 1,11,22,39,5
5,76,90,92,94,108,111,127,151,160,177,191,197,210
• Cobalt and Chromium wear particles
shown in animal models to induce carcinoma
80
• 3.7 fold increased rate of leukemia in
patients with metal on metal hip vs. metal
on polyethylene…NOT STATISTICALLY
SIGNIFICANT 203
• Overall, biologically plausible, but present
available data DOES support a causal link
between total hip or knee arthroplasty and
development of cancer 200
• ? Toxicity 23,96,117,121,122,171,200
• Serum Chromium levels as much as 50
times higher
• Serum Chromium levels as much as 100
times higher

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34
• Importance of these elevations not established
• ? Hypersensitivity 77
• Prevalence of dermal sensitivity in patients
with a total joint arthroplasty substantially
higher than general population
• Unclear if metal sensitivity is a contributing
factor to implant failure
• Currently no generally accepted test for
clinical determination of metal hypersensitivity
to implanted devices
• No clinical data beyond 10 years for second
generation metal on metal implants
• Implant costs
III. Ceramic on Ceramic Bearing Surfaces
A. History
• First ceramic on ceramic total hip performed
in France in 1970 by Boutin 21
• First ceramic on ceramic total hip implanted
in Germany in 1974 by Mittelmeier
and Walter 141,142
• The Autophor implant (Richards, Memphis,
TN), a Mittelmeier design, marketed
in the US but abandoned secondary to
unacceptable clinical results 38,123
• First generation implants had limited clinical
success (high fracture rate and aseptic
loosening) secondary to poor materials,
manufacturing, and component design;
not the bearing surface itself 46,74,82
• European scientists and clinicians lead
development of improved materials,
manufacturing, component design, and
implantation technique 142,165,202,207
• Simulator and retrieval studies demonstrate
ceramic on ceramic bearings have the lowest
wear volumes of all currently available
bearing couples 50,51,61,152,157,158,164,199,207,211
• New clinical studies on second and
third generation bearing surfaces ongoing
157,213
B. Design Issues
• First generation ceramic articulations:
Alumina (1970)
• Poor understanding of materials and
manufacturing 207,213
• Poor materials
- Large grain size
- Low density
• Poor manufacturing
- Large sphericity deviations
- Large mismatches (diametral clearance
and taper tolerance)
- Large pore size
• Second Generation Ceramic Articulations
• Alumina (1977)- Significant advances in
quality and manufacturing 37,85,182,207,215
• High purity: monophase material provides
long term stability
• High density: provides better surface
finish
• Small grain size: provides increased
strength
• Taper lock: improved tolerance matching
between mating parts
• Improved processing: clean room processing,
improved sintering techniques,
hot isostatic pressing, laser marking and
proof testing
• Low porosity
• Zirconia (1989)-Mixed clinical and in
vitro results 36
• 73% improved strength 34,54,65
• Improved fracture toughness (2X) 85,182
- Allows use of smaller diameter femoral
heads
• Strength and toughness at expense of
thermal stability 17,161
• 1/98 – 9/99: St Gobain Desmarquest
changes manufacturing process of
Zirconia femoral heads - ↑ fracture rate
and FDA recall
• Third Generation Ceramic Articulations
• Ceramic composites (i.e. Biolox forte
and delta)
• Wear and thermal stability of alumina
2,3
• Strength and toughness of zirconia 2,3
• Clinical and in vitro investigations ongoing
156,186

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C. Results
• First Generation Ceramic on Ceramic
Articulations
• French
• Ceraver-Osteal prosthesis- 10 year follow-up
154
- 12% aseptic loosening (15/16 were acetabular
components)
- 5 component fractures (3 heads, 2
cups)
- 82.6% 10 year survival
- Extremely low average wear rate on
retrieval (0.025um/yr.) 50
• German
• Mittelmeier prosthesis (minimum 10 yr
follow-up 141 )
- 22% aseptic femoral loosening
- 5 ceramic component fractures
• Lindenhof prosthesis (average 12.2 yr.
follow-up 213 )
- 25% revised for mechanical reasons
• 14% aseptic loosening
• 4 stem, 7 socket, 3 combined
• 8% fractured femoral heads
• 3% other
- Gross alumina wear noted in all retrieved
prosthetic components
• Poor quality ceramic
• United States
• Autophor prosthesis (2-12 yr. follow-up)
89,101,123, 217
- 5.4-36% revised for aseptic loosening
- 22-35% aseptic femoral sided loosening
- 1-48% aseptic socket loosening
- No ceramic fractures
- Variable amounts of osteolysis observed
(none to > 40%)
- Average wear 0.016mm/year on retrieval
101
- Average ceramic particle size 0.71um 217
• Ceramic on Ceramic Bearings in Young
Patients
• Ceraver-Osteal prosthesis in patients <
50 yrs 178
• 98% survivorship at 10 years
- 27% impending failures secondary to
aseptic acetabular component loosen-
ing
• Follow-up investigation to evaluate acetabular
fi xation of alumina socket 18
• 128 patients less than 40 years old
• Same Ceraver-Osteal stem for all patients
• 4 types of alumina acetabular fi xation
- Survival rates
• 90.4% for cemented alumina socket (10
yrs)
• 88.8% for screw-in ring with alumina insert
(10 yrs)
• 95.1% for press-fi t alumina socket (yrs)
• 94.3% for press-fi t titanium socket and
modular alumina insert (7 yrs)
• German Mittlemeier prosthesis in young
patients 88
• Minimum 5 year follow-up
• 1 revised (0.03%) at 60 months for cup
fracture
• Radiographic loosening in 3 additional
cases
• No evidence of femoral or acetabular
osteolysis
• Second and Third Generation Ceramic on
Ceramic Articulations
• Transcend Ceramic on Ceramic (Wright
Medical) 68
• Conducted with Food and Drug Administration
Investigational Device Exemption
- 333 patients enrolled
- Average follow-up 22 months
- No revision for aseptic loosening
- No component fractures
- 4 ceramic related complication
• 3 chipped liners: immediately replaced
intraoperatively
• 1 eccentrically seated liner: revised after
noted on post-op radiograph
• Alumnia/Alumnia Ceramic Bearing Investigational
Study 42
• 514 total hips randomized to conventional
metal on polyethylene or ceramic
on ceramic
• Prosthetic designs identical except for
bearing surfaces
• 2-4 year follow-up (Ceramic group)
- 0.06% (1) radiographic evidence acetabu-

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38
lar component aseptic loosening
- No component fracture or osteolysis
- 9 Peripheral chips (2.6%) @ insertion
D. Potential Advantages of Ceramic on
Ceramic Bearings
• Extremely low wear
• In vitro volumetric wear
• 0.01-0.05mm 3 /million cycles 61,152,157,199
• In vivo linear wear
• Retrieval wear rates as low as 0.016 mm/
year - 0.025mm/year 50,88,101,124,198
- 4000x less than historical metal on polyethylene
THA
• Increased wear seen with loose or vertical
sockets, femoral neck/socket impingement,
and poor quality alumnia 179,207
• Bioinert
• Usual reaction to ceramic particles is
fi brocytic type with few macrophages and
no giant cells 20,60,114,115
• PGE2 determination revealed less infl ammatory
mediators than metal on polyethylene
180
• Extreme Hardness
• Alumnia 4X harder (2000 HV) than THA
Cobalt-Chrome, Titanium, and Stainless
Steel 85,181
• Increased resistance to third body wear
• High Wettability
• Smaller wetting angle provides increased
lubrication and decreased adhesive
wear
• Alumina has best wettability compared
to all other bearing materials in clinical
use 192
• Larger Femoral Head Sizes
• Improved ROM and hip stability associated
with large heads without deleterious
increases in wear particles
E. Potential Disadvantages of Ceramic on
Ceramic Bearings
• Fracture
• Range 0.01% to 0.4% in recent extensive
reviews 64,78,81,179,185
• Multifactorial
• Material and design features of the ce-
ramic head
• Taper junction of femoral component
• Application technique of surgeon
• Patient-related factors (activity level,
etc.)
• 2 Zirconia head fractures out of 300,000
implanted 161
• Revision
• Should not apply new ceramic component
to a “used” trunion or liner locking
system
• Use alternative bearing material or revise
stem and / or liner
• Ceramic fragments can cause extensive
third body wear 103
• Technique sensitive
• Reduced range of acceptable acetabular
and femoral component positioning to
avoid impingement and edge loading 207
• Implant costs
• Ceramic heads > 2x more expensive than
Cobalt- Chrome (i.e. $400 vs. $900) 189
IV. Improved Polyethylene (Highly Crosslinked)
A. History
• Sir John Charnley implants fi rst total hip
with metal on polyethylene bearing surface
in 196231 • Well designed hip replacements with a
metal on polyethylene bearing demonstrate
low wear rates and good long-term
clinical results35 • Expansion of indications for THA in
younger and more active patients reveals
limitations of conventional polyethylene as
a bearing surface material
• Polyethylene wear identifi ed as the primary
cause of osteolysis and often the ultimate
7, 86,
cause of failure of many implants
124,125,174,175
• Alternative bearing materials against polyethylene
to decrease wear investigated
• Ion implanting and other surface hardening
techniques to cobalt-chromium and
titanium alloy femoral heads are reported
to both decrease and increase wear of op-

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posing polyethylene…clinical applications
presently unclear 44,135,140,170,184
• Investigations of ceramic on polyethylene
bearing surfaces overall report
lower polyethylene wear rates, but results
mixed 45,131,137,161,170
• Early attempts to improve polyethylene
(carbon- reinforced polyethylene, heatpressed
polyethylene, and Hylamer)
performed no better or worse than conventional
polyethylene 33,119
• Highly cross-linked polyethylene used in
industrial applications (i.e. coal-chutes) is
noted to improve wear resistance 136
• Highly cross-linked medical grade polyethylene
and techniques to decrease oxidation
demonstrate signifi cantly reduced
wear in hip simulator testing 133,146,209
B. Design Issues
• Cross-linking of Polyethylene
• The Chemistry
• UHMWPE consists of long chains of
carbon
• Cross-linking is the process by which covalent
C-C bonds are formed between the C
atoms of adjacent polyethylene chains
• Cross-links between chains are formed by
the production of free radicals (removal of
hydrogen atoms from the carbon chain)
and subsequent recombination with one
another to form covalent bonds and create
a 3-dimensional structure with improved
wear characteristics 133-185
• Free radicals can be produced by gamma
irradiation, electron beam irradiation or
chemically with peroxides
• If oxygen combines with the free radicals,
oxidation occurs which results in scission
of the polyethylene chains reduced molecular
weight with decreased mechanical
and wear properties 137,195
• The Manufacturing
• Goals: maximize cross-linking, minimize
oxidative degradation and minimize alteration
in mechanical properties (yield
strength, ultimate tensile strength, ductility,
etc…)
• Controversial issues: fabrication technique,
cross-linking technique, thermal
treatment, and terminal sterilization
methods.
• Fabrication of Polyethylene
• Only 2 suppliers of medical grade UHM-
WPE107, 116,118
• Three methods to convert raw powder
(resin) to a solid form: ram extrusion,
compression molding, and net-shape
molding
• Retrospective studies of conventional
polyethylene suggest components fabricated
by molding techniques undergo
substantially lower levels of oxidation
compared to polyethylene fabricated by
ram extrusion 41,67,69,107,206
• Clinical importance of fabrication technique
with today’s highly cross-linked, thermally
stabilized polyethylene is unclear 137
• Cross-linking Techniques
• Gamma Irradiation
• Historically done for sterilization
- 2.5 to 4 Mrads/components sealed in air
(oxygen) environment 136,134
- Oxygen combined with the free radicals
generated resulting in oxidative degradation
and very little cross-linking of the
surface layer 66,162,195
• Today done intentionally to induce crosslinking
- Irradiation done in an oxygen depleted

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environment to avoid oxidative degradation
(vacuum73, inert gases193, or O2
scavenger13)
- Polyethylene wear rate decreases with increasing
level of radiation-induced crosslinking
(dose-wear relationship) 133,146,209
• Greatest reduction in wear with increases
from 0-5 Mrads
• No additional benefi t after 15-20 Mrads
- Mechanical properties of polyethylene
adversely effected with higher doses of
gamma irradiation70,79,133,209 • Decreased yield strength, ultimate tensile
strength, and ductility, etc.
- Developers have differing opinions regarding
appropriate dose to optimize
clinical performance/decrease wear
while maintaining mechanical properties
of the material
• Electron Beam Irradiation
• Method successful at inducing a high
degree of cross-linking185 • Induces the cross-linking into the polyethylene
2500X faster than Gamma irradiation136
• Electron beam irradiation of polyethylene
at pre-heated temperatures provides
greater wear resistance and smaller reductions
of elongation to break than at room
temperature144 • Mechanical properties of polyethylene
adversely affected with higher doses of
144, 146
E-beam radiation
• Thermal Treatment
• Goal of thermal treatment is to minimize/
eliminate residual free radicals and the
potential for oxidation
• Two different techniques currently used
• Melting
- Polyethylene heated above its melting
temperature and changed from a partially
crystalline solid to a totally amorphous
solid16,133 - Mobilizes free radicals trapped in crystalline
region enhancing cross-linking and
minimizing the potential for long-term
oxidation16 - Polyethylene remains oxidation resistant
133, 194
even after accelerated aging
- Technique of choice currently for most
manufacturers
• Annealing
- Polyethylene heated to just below its
melting temperature
- Induces less change in material morphology
and material properties than does
remelting126 - Annealing in nitrogen decreases residual
free radicals194 - Oxidative degradation of the polyethylene
strength and wear resistance noted with
accelerated aging145 • Crystalline regions with free radicals may
136, 137
remain
• Terminal Sterilization
• Gamma Irradiation
• Used historically
• Regenerates free radicals and potential
for oxidative degradation
- Oxidative degradation minimized by
performing in an oxygen depleted
environment
• Non-Irradiation Methods107 • Gas Plasma and Ethylene Oxide
- No new free radicals regenerated
- No change in oxidative stability
• Comparisons Among New Cross-linked
Thermally Stabilized Polyethylenes137 C. Results of Highly Cross-linked Polyethylenes
• In Vitro/Hip Simulator Data
• Highly Cross-linked, Thermally Stabilized
Polyethylene (Ideal Environment)
• 4 most commonly used commercially used
polyethylenes have been tested
• All had decreased wear compared
to conventional/control polyethylene
133,134,146,147,209
- 85-95% wear reduction
• Highly Cross-linked, Thermally Stabilized
Polyethylene (Roughened Femoral
Heads)
• 3 commonly used commercial polyethylenes
tested. All had improved resistance
of third-body wear compared to conven-

Notas / Notes
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44
tional/control polyethlene 57,112,132 . Some,
however, report increased wear in highly
cross-linked polyethylene when articulated
against roughened femoral heads. 56
• In Vivo/ Clinical Data
• Highly Cross-linked, Thermally Stabilized
Polyethylene
• Clinical data scant (Martell et al.) 87
- Minimum 2 year follow-up of 39 crosslinked
(gamma XRT in N 2 ), thermally stabilized
(annealed) polyethylene inserts
- Linear wear (in vivo) 0.14mm/yr
- Volumetric wear (in vivo) 0.54mm 3 /yr
- Both linear and volumetric wear rates
were signifi cantly less compared to control
conventional polyethylene
• Highly Cross-linked Polyethylene without
Thermal Treatment
• Oonishi et al. 158
- Cross-linked with 100 Mrads of Gamma
radiation in air
- Cobalt-Chrome femoral heads
- Long-term wear rates
• 290um/year for non cross-linked (higher
than historically reported)
• 60um/year for cross-linked
• 79% reduction in wear
• Wroblewski et al. 214
- Chemically cross-linked with saline
process
- Ceramic (Alumina) Femoral Heads
- 19 patients with up to 8.3 yr. follow-up
• Extremely low wear (0.22mm/year)
• Question if wear rate secondary to ceramic
femoral head or highly cross-linked
polyethylene
• Grobbelaar et al. 75
- Cross-linked with 10 Mrads Gamma radiation
immersed in acetylene gas
- 30mm Chrome Cobalt Heads
- 14-21 yr follow-up
• “Lack of measurable wear”
D. Potential Advantages of Highly Crosslinked
Polyethylene
57,75,112,132-134, 146,147,158,209,214
• Decreased wear

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• Increased Oxidative Stability
E. Potential Disadvantages of Highly
Cross-linked Polyethylene
• Scant clinical data to confirm in vitro
data
• Decreased mechanical properties
70,79,133,144,146,209
• Biological response to wear particles
controversial
• Size and shape of particulate debris from
highly cross-linked and conventional polyethylene
similar 15
• Wear particle size decreases with greater
amounts of cross-linking and may create a
more intense osteolytic response 166
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arthro;lasty complicated by a malignat
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211. Wilson PD, Amstutz HC, Czerniecki
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WEAR OF THE ULTRA
HIGH MOLECULAR
WEIGHT POLYETHYLENE
CUP IN CHARNLEY LFA.
WHAT PROGRESS?
B. M. Wroblewski, P. D. Siney, P. A. Fleming
The John Charnley Research Institute,
Wrightington Hospital, Hall Lane,
Appley Bridge Near Wigan, U.K.
Wear of the ultra high molecular weight polyethylene
(UHMWPE) cup and the resulting
loosening has been shown to limit the long-term
results of the Charnley low-frictional torque
arthroplasty (LFA).
Factors affecting wear rates have been studied:
level of patient activity, effective roughness
of the stainless steel head, impingement and
the possible variations in wear characteristics
of UHMWPE. Since patients’ activity level
cannot be predicted or modifi ed, alternative
materials and modifi cations of the design were
examined.
The Charnley 22.225 mm diameter head in
alumina ceramic in combination with chemically
cross-linked polyethylene has now reached 20
years follow-up. The mean penetration rate
is 0.02 mm/year and none have exceeded
0.41 mm total penetration. No cup has been
revised
Zirconia ceramic in combination with UHMWPE
show 68% of cases having no measurable wear
with a follow-up to 13 years. Reducing the diameter
of the neck of the Charnley stem from 12.5
to 10mm has effectively increased the life of the
arthroplasty by the equivalent of 2mm of wear of
10-20 years. Since the problem of cup wear and
loosening is mechanical rather than biological
the long-term solutions are more likely to come
from materials rather than radical changes of
design of methods of component fi xation.

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THE INCIDENCE AND
VOLUME OF OSTEOLYSIS
AT A MINIMUM 5-
YEAR FOLLOW-UP WITH
HIGHLY CROSSLINKED
AND NON CROSSLINKED
POLYETHYLENE
C. A. Engh, MD
Anderson Orthopaedic Research
Institute, Alexandria, USA
Introduction:
In both laboratory and clinical studies, crosslinked
polyethylene has shown decreased
wear rates, but the effect on osteolysis still
needs to be examined. This study sought to
determine if the incidence and volume of osteolysis
decreased with use of a crosslinked
polyethylene. CT was used in this study
since it more accurately measures volume
than radiographs and can detect small lesions,
making it useful for the early detection
of osteolysis.
Materials and methods:
230 hips were randomized to a Marathon
crosslinked (Depuy) or Enduron non crosslinked
(Depuy) 4-mm lateralized polyethylene
between 1999 and 2000 in an IRB-approved
prospective study separate from this study.
76 study hips received a computed tomography
(CT) scan as part of routine clinical
follow-up. CT scans were analyzed using a
validated post-processing software package
(Muscular-Skeleton Analysis Software) that
allowed a blinded observer to defi ne osteolysis
and determine osteolysis volume.
Results:
The average length of follow-up was 6.1 ± 0.4
years. 40 hips had a Marathon polyethylene
and 36 had an Enduron polyethylene. There
were 12 (30.0%) Enduron and 6 (16.7%)
Marathon cases with at least one osteolytic
lesion. There was no signifi cant difference (p
= 0.19) in the incidence of osteolysis between
the two groups. The average lesion volume
for Enduron cases was 7.0 ± 6.7 cm 3 , which
was signifi cantly larger (p = 0.001) than the
average lesion volume for Marathon cases
of 1.2 ± 0.7 cm 3 .
Discussion:
At this short follow-up interval, Marathon
crosslinked polyethylene has shown to have
a decreased volume of osteolysis over Enduron
non crosslinked polyethylene. Longer
follow-up is necessary to determine if Marathon
crosslinked polyethylene will continue to
demonstrate the encouraging improved wear
and osteolysis characteristics found in both
the literature and the current study.
METAL-METAL COUPLE –
SCIENTIFIC BASES
E. Robinson, T. Singh Aulakh, M. Khan,
J. Herman Kuiper, J. Richardson
The Robert Jones & Agnes Hunt
Orthopaedic Hospital, UK
Science is based on observation. Any hypothesis
should then fi t those observations
and be open to testing. Metal on metal hip
replacement was very successful with a
design by Ring some 30 years ago. There
were diffi culties however with initial fi xation to
bone. John Charnley solved that problem by
the development of bone cement. His second
solution was a metal on polythene articulating
surface which had demonstrable lower friction
and would never squeak. Even at that time
there was much debate on what was best and
John Charnley used the threat and concern
of cancer to help swing opinion towards his
own design of hip replacement.
The metal on polythene hip has stood the test
of time but John Charnley himself insisted it

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only be used for the older patient of 65 years
or more. Some excellent long term results
have been obtained in patients who had some
other limiting factor from a young age that
prevented them attaining a high mileage each
year. We all know the problems of osteolysis
related to the polythene debris from a metal
on polythene joint. It is for these reasons
there is again a logical argument for using
a metal on metal articulation in the younger
and active patient.
The Outcome Centre at Oswestry has been
following 5000 patients now out to 9 years.
This is an independent review where information
is gathered directly from patients.
This has found a very high level of function
and activity in patients with metal on metal
resurfacing hip replacement. There is good
survival out to 9 years with 97% survival at a
minimum of 7 years. This group of patients is
from a combined series of several surgeons
across the world who are new to using this
technique.
Similarly, I have excellent results now out
to 10 years with the Metasul articulation on
a Thrust Plate. This is the shortest possible
uncemented stem with strong initial stability
and rigidity. These patients likewise have a
high level of activity and the 8 year follow up
was 98% survival.
What of the metal ions absorbed? Certainly
in a minority of patients these have a hypersensitivity
response which causes pain and
cyst formation. All patients absorb some
metal in the form of chromium and cobalt.
These levels are highest in the joint and
adjacent to the metal implants. Alterations
in circulating cells have been noted and this
causes concern. However, the observation
of a local sarcoma adjacent to a metal implant
is very rare indeed considering the numbers
implanted worldwide and this includes a
whole range of metal implants. The observation
therefore is that in practice and indeed
over many years it is unlikely that the risk of
a local cancer is signifi cant. Further observations
and studies are needed to identify and
quantify risks of leukaemia.
METAL-METAL BEARING
SURFACES: THE WAY
OF THE FUTURE?
S. J. MacDonald, MD, R. W. Mc-
Calden, MD, R. B. Bourne, M.D.,
C. H. Rorabeck, M.D., D. Chess, M.D.
Health Sciences Centre, Ontario, Canada
Objective: Polyethylene wear continues
to be the most signifi cant issue following
total hip arthroplasty (THA) leading to the
current increase in use of alternative bearing
surfaces. We performed a prospective,
randomized, blinded clinical trial comparing
metal versus polyethylene bearing surfaces
in patients receiving THA.
Method: Forty-one patients were randomized
to receive a metal (23) or a polyethylene
(18) insert with identical femoral and acetabular
components. Patients were evaluated
pre-operatively, at 3, 6, 12 months and annually
thereafter, including an evaluation of
erythrocyte and urine cobalt, chromium, and
titanium, outcome measures (WOMAC, SF-
12, Harris Hip Score) and radiographs.
Results: No patients were lost to follow-up.
At an average 7.2 (range 6.1 – 7.8) years
follow-up there were no differences in any
outcome measures or radiographic fi ndings.
Patients receiving metal liners had signifi -
cantly elevated metal ion measurements. At
most recent follow-up erythrocyte cobalt levels
were 7 times elevated (median 1.2 ∗g/L
(metal) vs 0.18 ∗g/L (poly), p

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0.36 ∗g/day (poly), p

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11.20 - 18.55 h
CADERA / HIP
Fijación de los componentes protésicos
Fixation of the prosthetic components
Moderadores / Moderators: Eduardo García-Cimbrelos, James Richardson, Charles Engh
CEMENT OR
CEMENTLESS FIXATION
R. Geesink
University Hospital Maastricht, Netherlands
ROLE OF THE CEMENT IN
THE FIXATION OF THE
PROSTHETIC COMPONENTS
J. Timperley
Princess Elisabeth Orthopeadic
Hospital, Exeter, UK
CHARNLEY LOW-FRICTIONAL
TORQUE ARTHROPLASTY
– 44 YEARS OF CLINICAL
EXPERIENCE:
B. M. Wroblewski, P. D. Siney,
P. A. Fleming
The John Charnley Research Institute,
Wrightington Hospital, Hall Lane,
Appley Bridge Near Wigan, U.K.
Charnley low-frictional torque arthroplasty
(LFA) was introduced into clinical practice in
November 1962 and to date over 35,000 have
been carried out at Wrightington Hospital.
The concept has remained, but modifi cations
and improvements and changes in the design
have been an integral part. The longest
surviving patient with a bilateral LFA that is
still attending and has not needed a revision
has just passed 40 years of clinical success.
Long-term follow-up naturally selects
only young patients where activity level, life
expectation and demand on the arthroplasty
is high. Forty-four patients (50 LFAs) have
now passed 30 years of follow-up. Their
mean age at surgery was 47.5 years (22-
65). Clinical results remain excellent. Mean
cup penetration was 0.06mm/year – high
wear was incompatible with long-term success.
Proximal strain shielding was the main
problem on the femoral side, but endosteal
cavitation did not occur if the stem was distally
unsupported by cement.

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The information suggests that excellent
long-term results can be achieved with a
well-conceived design and good surgical
technique.
OSSEOINTEGRATION IN
PRIMARY CEMENTLESS
HIP FIXATION
J. D. Blaha, M.D.
University of Michigan. Medical
School, USA
Osseointegration implies the formation of a
“single” (i.e., integrated unit) between bone
and, in the case of a joint replacement arthroplasty,
a prosthetic component. Although it
has not always been such in common usage,
osseointegration and fi xation are synonymous
terms. Fixation, for total joint replacement,
implies that a prosthesis is bonded
to the bone in such a way that there is no
relative motion at the interface between the
prosthesis and the bone. Osseointegration is
a term that describes the histological features
by which this fi xation is achieved and implies
the mechanical features of a fi xed implant.
Many total joint prostheses have been successful
at the hip. There are numerous
shapes and sizes of implants that have associated
with successful clinical outcomes.
The clinician is presented with a plethora
of seemingly contradicting claims regarding
the need for certain design features of
implants in order to achieve a successful
result. (E.g., “maximum fi t and fi ll”, porous
coating, hydroxylapetite coating, “scratch fi t”
grit-blasting etc.)
This presentation suggests a unifying explanation
for the success of implants. This
explanation is based on dividing the time after
implantation into four periods: primary stability,
intermediate stability, secondary stability
and long-term remodeling.
Primary stability: For a cementless implant
this period would be during the operative
intervention when the prosthesis is inserted
into the bone. The interference of the implant
in the bone leads to a “press-fi t” that will hold
the implant stable.
Intermediate stability: For a cementless implant
this period begins after primary stability
is achieved in the OR and ends when bone
apposition to the implant leads to secondary
stability and osseointegration.
Secondary stability: When bone apposition
to the implant has progressed so that
the implant has been “fi xed” (i.e., no relative
motion at the interface of the implant to the
bone) secondary stability has occurred. The
time required to achieve this is not certain
but bone healing is generally thought to take
between 6 and 12 weeks.
Long-term remodeling: The progressive
change of bone at the interface to hypertrophy
in areas of increased load and atrophy
in areas of no load (i.e., the expression of
Wolf’s law of bone) leads to this long-term
remodeling. Other conditions at the interface
(e.g., fracture, infection, debris induced bone
resorption etc.) can lead to dissolution of the
bone and loosening of the implant.
In fact, this same concept can be applied to
cemented arthroplasty as the ultimate fi xation
of a cemented joint must be against live bone
and the term osseointegration is appropriate
for the cemented joint as well.

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OUTCOME OF TOTAL HIP
ARTHROPLASTY USING
EXTENSIVELY POROUS-
COATED COMPONENTS AT
20-YEAR FOLLOW-UP
C. A. Engh, MD
P. J. Belmont, Jr., MD
S. E. Beykirch, BS
R. H. Hopper, Jr, PhD
C. A. Engh, Jr, MD
Anderson Orthopaedic Research
Institute, Alexandria, VA, USA
Introduction: Porous-coated total hip arthroplasty
components were introduced with
the hope that they would achieve durable
biologic fi xation. The Anatomic Medullary
Locking stem and TriSpike cup were among
the fi rst porous-coated components used
in North American. Patients from our initial
clinical series using these components are
now eligible for 20-year follow-up.
Methods: Between October of 1982 and
December of 1984, we performed 223 total
hip arthroplasties among 215 patients using
the Anatomic Medullary Locking hip system
(DePuy). The porous-coatings on the cup
and stem were achieved by sintering chromecobalt
beads to a chrome-cobalt substrate.
The mean age at surgery was 55 ± 15 years
(range 16 to 87 years). Ninety-one patients
(93 THAs) with less than 20-year follow-up
are now deceased. The mean follow-up
for the 130 remaining THAs is 21.1 ± 2.4
years.
Results: Forty-seven THAs have required
component revisions. In 22 cases, the fi rst
revision was limited to a liner exchange for
polyethylene wear or osteolysis. Seven hips
with pelvic osteolytic lesions that measured
at least 1.5 cm2 had loose cups at the time
of revision. Three stems have been revised
for aseptic loosening. Owing to the high
incidence of wear-related revisions, Kaplan-
Meier survivorship at 20-year follow-up,
using component revision for any reason as
an endpoint, was 75 ± 7% (95% confi dence
intervals). In contrast, survivorship using
stem revision for any reason as an endpoint
was 98 ± 2% at 20-year follow-up. Survivorship
of the porous-coated shell, using cup
revision for any reason as an endpoint, was
86 ± 5% at 20 years.
Discussion: Despite revisions for wear-related
complications in this relatively young
patient population, the fi xation achieved with
these porous-coated components remained
durable through 20-year follow-up. Acetabular
osteolysis has been associated with cup
migration but femoral osteolysis has never
resulted in stem loosening.
EXTENSIVELY POROUS
COATED STEMS: OUR
GOLD STANDARD
W. Paprosky
Rush Arthritis & Orthopaedic Institute
St. Luke’s Medical Center
Chicago, Illinois, USA

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CEMENTLESS THA IN
PATIENTS LESS THAN 50
– LONG TERM RESULTS.
C. H. Rorabeck, MD
Health Sciences Centre, Ontario, Canada
Providing a long-lasting total hip arthroplasty
(THA) for patients under 50 years of age
with hip arthritis remains one of the greatest
challenges for modern arthroplasty surgery.
Between 1983 and 2000, 221 patients less
than 50 years old underwent 299 uncemented
THAs at our institution. A minimum 5 and
maximum 15-year survival was assessed,
with revision as the end-point. Latest radiographs
were assessed for polyethylene
wear, component loosening and osteolysis.
Femoral stem survival was 99.3 (98.4-100)
%, 98.9(97.7-100) % and 96.8(92.5-100)
% at 5, 10 and 15 years for all designs.
Including all acetabular component designs
survival was 98.7(97.4-100) %, 84.6(78.8-
90.4) % and 52.5(40.7-64.3) % at 5, 10
and 15 years. Excluding polyethylene liner
exchange, acetabular survivorship increased
to 98.9(97.8-100) % (5 yr), 90.6(85.7-95.5) %
(10yr), and 65.3(52.8-77.8) % (15yr). THAs
performed for hip dysplasia had lower 10 and
15-year survival (p=0.009; p=0.006). 69 revisions
have been performed, the commonest
indication being polyethylene wear (n=33).
Zirconium on polyethylene articulations had
signifi cantly lower acetabular revision rates
compared with cobalt-chrome on polyethylene
(p=0.02). Uncemented femoral stems
provided over 90% survivorship at a minimum
15-year follow-up in patients younger than 50
at their index operation. Contemporary bearing
surfaces in association with such stems
may provide long lasting THAs even in young
active patients.
CLINICAL RESULTS AND
HISTOLOGICAL FINDINGS OF
A LOW MODULUS
COMPOSITE STEM
V. M. Goldberg, M.D.
Department of Orthopaedics
Case Western Reserve University
University Hospitals of Cleveland
Cleveland, Ohio, USA
Introduction: Osteolysis secondary to stress
shielding has been attributed to high femoral
stem stiffness in total hip arthroplasty (THA).
The EPOCH (Zimmer, Warsaw, IN) stem has
reduced stiffness due to a smaller cobalt alloy
core, surrounded by polyaryletherketone
and titanium mesh for bony ingrowth. Our
fi ndings from a prospective clinical trial of
this implant, including histological analysis
of retried implants from autopsy.
Materials and methods: Twenty-eight (19
males, 9 females, average age 51.3 years,
range 23-67) with primary or secondary osteoarthritis
underwent a primary THA using
the EPOCH stem and were followed by an
average of 10.2 years. Harris Hip Scores
were obtained preoperatively and at 2 year
intervals post-operatively. Two femurs were
obtained at autopsy 13 and 48 months after
surgery. The femurs were sectioned proximally-distally
and evaluated histologically by
quadrants: anteromedial (AM); anterolateral
(AL); posteromedial (PM); posterolateral (PL).
They were graded by two observers for bone
ingrowth into the mesh (0-2), ongrowth onto
the mesh (0-4), and extent of bone fi ll (new
and old) around the implant (0-3).
Results: Preoperative hip scores averaged
55.5 (range 33-78) and improved to
97.2 (range 78-100) at last follow-up, with 2
patients having scores below 90 (thigh pain
was present in one of these patients). For

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both implants, histological evaluation showed
substantial bone ingrowth and ongrowth in
all four quadrants, along the entire length of
the implants. Ingrowth generally occurred to
the maximum mesh depth. The AM and PL
quadrants exhibited overall less ongrowth
compared with the AL and PM quadrants.
Extent of bone fi ll was also less in the AM
and PL compared with the other two quadrants.
The cortical bone demonstrated some
osteoporosis.
Discussion: This follow-up of hips treated
with the EPOCH ® suggest satisfactory clinical
performance and histological evidence of a
successful biological integration of this low
modulus stem. Although the implants were
associated with excellent results to date,
longer follow-up will be necessary.
CEMENTED CUPS: RESULTS
AND TECHNIQUE
J. Timperley
Princess Elisabeth Orthopeadic Hospital
Exeter, UK
COTILOS ROSCADOS
¿CUÁNDO?
E. García Cimbrelo
Hospital La Paz, Madrid, España
La aparición de malos resultados de las
cúpulas cementadas ocasionó el desarrollo
de las cúpulas no cementadas. Las primeras
cúpulas no cementadas durante los
años setenta adoptaban una forma más o
menos troncocónica con espiras roscadas
aumentando su superfi cie lisa de contacto
con el acetábulo con el fi n de favorecer la
estabilidad primaria entre el implante y el
hueso y la posterior unión biológica. El roscado
tiene, por tanto, como concepto dar una
fi jación inmediata rígida que permita obtener
la inmediata osteointegración. Utilizando
una aleación de cobalto-cromo y molibdeno,
Lord es el primero en diseñar una cúpula de
superfi cie lisa y roscada con intención de obtener
una macrointegración (1). En aquellos
años Mittelmeier utiliza una cúpula roscada
de cerámica (2). El modelo Mecring, muy
popular en los años ochenta, fue otro diseño
roscado con un segmento esférico. En los
primeros años, los resultados iniciales fueron
favorables por lo que su uso se generalizó,
especialmente en Europa.
Posteriormente, diferentes publicaciones
informaron de frecuentes fracasos con malos
resultados clínicos a medio plazo y con altas
cifras de afl ojamiento que alcanzaban hasta
el 37% de los casos. Las roscas de superfi cie
lisa de aquellos cotilos troncocónicos, aunque
proporcionaban una buena estabilidad
primaria a la cúpula, lo que se podía observar
el momento de la cirugía, sin embargo, estas
roscas, aparentemente bien fi jas al hueso,
no se osteointegraban y producían un tejido
fi broso a su alrededor, incluso en aquellos
casos en que no se observaban líneas transparentes
en las radiografías tomadas durante
el seguimiento. La mayoría de las roscas no
estaban en contacto, o sólo marginalmente,
con el hueso acetabular (3-6). Estos malos
resultados ocasionaron el abandono de los
cotilos roscados y la generalización de las
cúpulas hemisféricas.
Sin embargo, las primeras generaciones de
cotilos hemisféricos no se adaptaban bien al
acetábulo no hemiesférico, incluso tras el fre-

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sado. Las superfi cies de aquellos implantes,
con bolitas de cromo-cobalto (PCA), malla de
titanio (Harris-Galante), lisas con cubierta de
hidroxiapatita (Osteonics), etc., requerían de
tetones antirrotatorios o tornillos suplementarios
para favorecer la osteointegración, no
siendo infrecuente la aparición precoz de
afl ojamientos de implante. Además, estas cúpulas
hemiesféricas incluían polietilenos de
escaso grosor con un defectuoso mecanismo
de bloqueo que favorecía su disociación y
rotura (ACS) así como la suelta de partículas
de polietileno producidas por el desgaste y
la producción secundaria de osteolisis (7,8).
Las cúpulas lisas hemiesféricas iniciales
tenían altas cifras de afl ojamiento debido a
que las cargas fi siológicas producían mayores
solicitaciones por cizallamiento en la
interfaz, de modo que si la cúpula no estaba
bloqueada por algún elemento suplementario
las fuerzas de cizallamiento son 10 veces
mayores.
Zweymüller continuó con el empleo de cotilos
roscados pero con superfi cie porosa
de titanio (Allofi t). Los resultados a largo
plazo publicados por diferentes series fueron
excelentes con supervivencia de 97% a 10
años (9-11). Es pues la necesidad de una
superfi cie porosa, más que la forma, lo que
favorece la osteointegración tanto de las
cúpulas troncocónicas roscadas como de las
cúpulas hemiesféricas. Perka y cols también
han referido excelentes resultados con la
cúpula Allofi t en caderas displásicas (12),
Sin embargo, la mayor resección de tejido
óseo y la alteración de la anatomía acetabular
sigue siendo la mayor queja en relación
con los cotilos troncocónicos roscados, lo
que llevó posteriormente a Zweymüller a
cambiar la forma de la cúpula. Así el cotilo
Bicon-Plus mantiene su estructura porosa
de titanio y sus roscas para favorecer la
estabilidad primaria, pero rediseña la forma
para hacerla más hemiesférica con el fi n de
respetar la estructura acetabular. El autor
refi ere excelentes resultados en una serie
de 215 casos con más de 10 años de seguimiento
con sólo tres casos de revisión,
un caso por infección, otro por afl ojamiento
aséptico, y el tercero por rotura del implante.
En esta serie el autor no refi ere ningún caso
de excesivo desgaste del polietileno y la casi
ausencia de osteolisis, lo que cree debido
al anclaje estable del polietileno dentro de
la cúpula metálica que impediría cualquier
movimiento. La delgada pared metálica de la
cúpula Bicon-Plus permite un mayor grosor
del polietileno. El estudio radiográfi co de la
serie permite observar igualmente la neoformación
de hueso entre las roscas rellenando
los espacios vacíos lo que es señal de una
excelente fi jación primaria incluso en presencia
de defectos óseos (13).
Por tanto, el concepto de los cotilos roscados
es actualmente muy discutido, siendo
en los países anglosajones y escandinavos
donde se encuentran las mayores reservas.
Recientes series insisten en que los malos
resultados se debían a la superfi cie lisa tanto
metálica como de cerámica, de los primeros
implantes, lo cual también sucedía con las
cúpulas hemiesféricas, incluso añadiendo
una capa de hidroxiapatita. Los buenos
resultados recientes con cúpulas roscadas
y porosas de titanio se basan en la mayor
estabilidad rotacional, incluso en presencia
de defectos óseos, lo que hace que su utilización
sea preferida por algunos autores
en cúpulas displásicas (12) o en cirugía de
revisión donde una cúpula hemiesférica es
difícil de adaptar por la forma irregular del
acetábulo. Recientemente Schroeder y cols
refi eren 95% de supervivencia en cirugía de
revisión, con defectos óseos, utilizando la
cúpula Allofi t (14).
Referencias
1. Lord GA, Ardí JR, Kummer FJ. An uncemented
total hip replacement. Experimental
study and review of 300 madreporique
arthroplasties. Clin Orthop 1979;141:2-
16.
2. Mittelmeier H. Total hip replacement

Notas / Notes
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with the Autophor cement-free ceramic
prosthesis. In: The cementless fi xation
of hip endoprostheses (Ed Morscher E).
Springer , New York; 225-241, 1984
3. Engh CA, Griffi n WL, Marx CL. Cementless
acetabular components. J Bone Joint Surg
Br 1990;72:53-59.
4. Capello WN, Colyer RA, Kernek CB,
Carnahan JV, Hess JJ. Failure of the
Mecron screw-in. J Bone Joint Surg Br
1993;75:835-836.
5. Garcia-Cimbrelo E, Martínez-Sayanes
J-M, Minuesa A, Munuera L. Mittelmeier
ceramic-ceramic prosthesis after 10 years.
J Arthroplasty 1996;11:773-781.
6. Malchau H, Herberts P, Wang YX, Kärrholm
J, Romanus B. Long-term clinical
and radiological results of the Lord total
hip prosthesis. A prospective study. J Bone
Joint Surg Br 1996;78:884-891.
7. Berry DJ, Barnes CL, Scott RD, Cabanela
ME, Poss R. Catastrophic failure of the
polyethylene liner of uncemented acetabular
components. J Bone Joint Surg
Br 1994;76:575-578.
8. Gonzalez della Valle A, Ruzo PS, Li S, Pellicci
P, Sculco TP, Salvati EA. Dislodgment
of polyethylene liners in fi rst and secondgeneration
Harris-Galante acetabular
components. A report of eighteen cases. J
Bone Joint Surg Am;2001;83:553-559.
9. Delaunay C, Kapandji Al. Survival analysis
of cementless grit-blasted titanium total
hip arthroplasties. J Bone Joint Surg Br
2001;83:408-413.
10. Grübl A, Chiari C, Gruber M, Kaider A,
Gottsauner-Wolf F. Cementless total hip
arthroplasty with a tapered, rectangular
titanium stem and a threaded cup. A minimum
ten-year follow-up. J Bone Joint Surg
Am 2002;84:425-431.
11. Garcia-Cimbrelo E, Cruz-Pardos A,
Madero R, Ortega-Andreu M. Total hip
arthroplasty with use of the cementless
Zweymüller Alloclassic syatem. A ten to
thirteen-year follow-up. J Bone Joint Surg
Am 2003;85:296-303.
12. Perka C, Fisher U, Taylor WR, Matziolis
G. Developmental hip dysplasia treated
with total hip arthroplasty with a straight
stem and a threaded cup. JBJS Am 86-
Am:312-19,2004.
13. Zweymüller K, Steindl M, Schwarzinger
U. Are consecutive cementless threaded
double-cone titanium cup justifi ed?. 10year-results
with a new method. AAOS
Meeting 2006. Paper 13, Chicago (IL).
14. Schröeder JH, Matziolis G, Tuischer J,
Leutloff D, Duda GN, Perka C.The Zweymüller
threaded cup. A choice in revision?.
Migration analysis and follow-up after 6
years. J Arthroplasty 2006;21:497-502.
WEAR OF UHMWPE,
ENDOSTEAL CAVITATION
AND COMPONENT
LOOSENING - MECHANICAL
OR BIOLOGICAL?
B. M. Wroblewski, P. D. Siney,
P. A. Fleming
The John Charnley Research Institute,
Wrightington Hospital, Hall Lane,
Appley Bridge Near Wigan, U.K.
With increasing follow-up of cemented total
hip arthroplasties (THA) attention became
focused on the localised loss of endosteal
bone of the femur and demarcation of bonecement
interface of the cup. Histopathological
studies have identifi ed various substances
found in the peri-prosthetic membrane which
were shown to be capable of bone resorption.
These fi ndings have formed the basis of the
biological cause of component loosening.
The proponents of the mechanical causes
of component loosening would suggest that
suffi cient evidence is available to suggest
the mechanical causes. Improved methods
of fi xation, reducing the likelihood of neck impingement
have reduced failure rates. Even
increasing the volume of UHMWPE wear particles
shed into the tissues had no effect on

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the outcome of stem fi xation. Reducing the
diameter of the neck from 12.5 to 10mm had
no effect on wear but reduced cup loosening
by over 50%. Proponents of the mechanical
theory have a number of solutions; the proponents
of the biological theory of component
loosening can either modify tissue response
or abandon the procedure. With new materials
and a better understanding of the problem
of osteolysis, it is likely that the subject will
become of academic interest only.
INTERPRETING
OSTEOLYSIS DEFECTS
C. A. Engh
Anderson Orthopaedic Research Institute
Alexandria, VA, USA
Osteolysis is a frequent radiographic fi nding
complicating cementless total hip arthroplasty.
When the acetabular cups are
poorly fi xed, osteolysis dissects around the
non-bone ingrown interface causing symptomatic
cup loosening. This type of lysis has
been termed linear osteolysis. Well-fi xed
acetabular components develop expansile
lysis. These lesions develop when joint fl uid
containing particulate debris invades soft
bone near the joint. The communication
pathway between these lesions and the joint
can be either through holes in modular cups
or around the rim with no holed non-modular
cups. When lesions develop through the
holes in the cup and remain small they are
usually not visible on AP radiographs since
they are hidden behind the cup. However
once these lesions develop a volume larger
than 10 cubic centimeters they usually become
visible on an AP radiograph. Cups
without holes develop expansile lysis around
the rim. These lesions usually develop at the
superolateral or inferomedial edges of the
cup and their progression and size can be
more easily followed on plain radiographs.
Since expansile osteolysis usually does not
result in cup loosening, these lesions are
asymptomatic.
We have found that computed tomography
(CT) is a better diagnostic tool for detecting
plain pelvic osteolysis than x-rays. We do
not recommend obtaining CT scans routinely
because it is costly and associated with a high
radiation dosage. However, once osteolysis
is suspected on x-ray we obtain a CT scan
to confi rm the diagnosis. We also use CT
scans to determine if the lesions are rapidly
expanding.
If it is determined that a patient needs revision
surgery, a CT scan is also useful for planning
the surgery. We use the CT to determine
osteolysis volume, whether or not the osteolysis
communicates with the joint space and
whether the lesion is contained by the medial
wall. The three-dimensional appreciation of
the lesion location obtained from the CT images
also help the surgeon in planning the
best surgical access route for curetting and
grafting the defect. During surgery we recommend
retaining well fi xed cups. We have four
objectives: 1) to decrease polyethylene wear
by replacing the polyethylene liner with one
that will wear less, 2) to remove the tissue
producing the lysis, 3) to fi ll the defect with
a bone graft substitute, and 4) to attempt to
block the communication pathway between
the defect and the joint space. Finally, we
found that CT is a much better method for
evaluating the results of our treatment than
plain radiographs.

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MECHANISMS OF LONG
TERM FAILURE IN
CEMENTLESS ACETABULAR
COMPONENTS
J. Galante, J. Jacobs, R. Urban
Rush Arthritis & Orthopaedic Institute, St.
Luke’s Medical Center, Chicago Illinois, USA
Histopathological fi ndings were reviewed on
retrieved autopsy specimens.
The study group consisted of twenty four
primary porous-coated Ti acetabular cups
(HG1 or HG II) retrieved at autopsy 5 to 21
years after implantation.
All specimens exhibited bone ingrowth with
more bone present at the components rim
and in the vicinity of screws. The extent was
35% (7 to 70%).
Particles within granulomas were present within
holes and in the rim in all components.
Expansion of granulomas through the screw
holes into the periprosthetic bone was obvious
in the longer term specimens.
Granuloma penetration was deeper along
screw tracts extending often through the
whole length of the screw. Screw holes with
or without screws were the main pathway
for extension of granulomas into the retroacetabular
bone.
Pelvic granulomas increased from a few millimeters
at 5 to10 years to ballooning massive
lesions at longer follow up, most often not
visualized on plain radiographs. In all of the
long term cases there was invasion of the
interface and of the porous coating itself.
The mean volumetric wear rate was 47 mm3/
yr. Damage to the back side of the liner was
moderate.
The mechanism responsible for long term
failure is related to wear and granuloma
formation.
These phenomena can lead to massive pelvic
osteolysis and or eventual loosening as the
actual causes of failure.
BASIC SCIENCE OF
HA COATINGS
R. Geesink
University Hospital Maastricht, Netherlands
PRÓTESIS MODULAR
CON HIDROXIAPATITA
A. Navarro - R. López
Hospital Universitario de Traumatología
Vall d’Hebrón, Barcelona, España
La principal diferencia entre la fi jación cementada
y la no cementada de los vástagos en
prótesis de cadera, reside en la distribución
de presiones en el intersticio metal-hueso.
Con el uso del cemento se intenta obtener
un reparto uniforme de la transmisión de
fuerzas desde el vástago al tejido óseo
circundante, mientras que con los sistemas
no cementados existen zonas en las que no
hay contacto con hueso, lo que evidenciaría
el denominado “mito del press-fi t”.
La hidroxiapatita (HA) ha demostrado ser un
muy buen material para el intersticio huesometal,
presentando una serie de ventajas
respecto a otros materiales. Por sus propiedades
osteoconductivas, la osteointegración
de los implantes es más rápida, presenta
buena tolerancia al micromovimiento y es
capaz de puentear distancias de salto mayores.
Todo ello podría favorecer el press-fi t

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en implantes no cementados, dejando de
ser un mito.
Nuestra experiencia en prótesis no cementadas
recubiertas de hidroxiapatita ha sido
satisfactoria, pero en ocasiones la morfología
femoral no nos facilita la concordancia
de tamaños entre la región metafi saria y la
diafi saria, lo cual nos fuerza mucho en la
elección del tamaño de la prótesis. Con el
diseño de un implante femoral modular hemos
conseguido mejorar la discordancia que
a veces se producía debido a los diferentes
tipos morfológicos.
Desde abril del 2000 hasta noviembre del
2005 hemos implantado 283 vástagos modulares
con buenos resultados clínico-radiológicos.
El estudio por TC en 43 pacientes
demostró la correcta osteointegración del
implante, así como la distancia de salto que
era capaz de osteoconducir la HA.
HYDROXYAPATITE ON
THE STEM IN PRIMARY
THA – DOES IT HELP?
C. H. Rorabeck, MD
Health Sciences Centre, Ontario, Canada
HA coated tapered femoral stems work
extremely well, however, I don’t believe that
there’s any added value when compared to
porous coated tapered femoral stems. Studies
have been done comparing H.A. coated
stems with a grip blasted femoral stems.
Hamudoch, in a prospective randomized
study comparing 25 grip blasted and 25 HA
coated stems found, at a mean 8.6 year follow
up that there was slightly more migration
in the grip blast stems compared to the HA
coated stems; however, neither stem required
revision. Retrieval studies, looking at the
bone remodeling around HA porous coated
and grip blasted stems noted that HA coating
seems to increase the amount of ingrowth.
Thus, the early data would suggest that
HA coating is indeed helpful for promoting
early bony ongrowth or ingrowth; however,
as the Swedish Arthroplasty Register noted,
in a comparison of primary cemented versus
uncemented total hip replacements in
patients less than 60 - that uncemented
circumferentially porous coated or HA coated
had comparable survivorship and that both
were better than cement. The concern, as it
relates to hydroxyappetite is the possibility of
debris generation when the implant has been
inserted. Several papers have documented
the issue of polyethylene wear and osteolysis
associated with HA debris in the interface.
The other concern related to HA is associated
with cost.
The experience which I am reporting today,
relates to1300 Synergy cementless stems
inserted at our institution with an average age
of 61.5 years and a predominance of males.
Osteoarthritis was the underlying disease in
90% . A subset of this group underwent a
prospective randomized comparison, comparing
Synergy grip blasted and Synergy
HA coated.
Sixty-eight (68) HA grip blasted tapered
Synergy cementless stems were prospectively
randomized with 68 proximally porous
coated Synergy tapered cementless stems.
Data is now out to 7 years in both groups.
There had been no failures of fi xation in either
group and no evidence of aseptic loosening
or stem subsidence in either group. Detailed
radiographic analysis of the patients failed
to reveal any difference between the HA
coated stem versus the proximally porous
coated stem. A careful clinical assessment
likewise demonstrated no difference. Harris
Hip Scores in excess of 94% were similar in
both groups. Similarly, an analysis of the
WOMAC revealed a signifi cant improvement
in the WOMAC scores which was consistent
out to 7 years. There was no statistical
difference between WOMAC scores in the

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HA coated group versus the porous coated
group. A careful analysis of the complications
of both groups demonstrated 1 reoperation
for periprosthetic fracture which presented at
6 weeks following a fall down a fl ight of stairs.
There was no detectable subsidence in either
the HA group or the porous coated group.
In conclusion therefore, tapered cementless
femoral stems work extremely well, better
than cemented stems utilizing third and fourth
generation cementing techniques. This is
particularly true in patients less than 60 years
of age. A careful analysis of the effi cacy of
hydroxyappetite on a grip blasted titanium
surface as opposed to a proximal porous grip
blasted surface, revealed no advantage to
hydroxyappetite. Thus, it would be our opinion
that hydroxyappetite coating on a tapered
press fi t stem is of no added value.
TANTALIO ¿MATERIAL
DE FUTURO?
M. Fernández Fairen
Barcelona, España
El tantalio (Ta) es un metal noble, altamente
biocompatible, resistente a la corrosión, dúctil
y tenaz. Es un magnífi co material para fabricar
sistemas porosos de recubrimiento de
implantes protésicos, para la fi jación de los
mismos al hueso. Por técnicas de deposición
de 40-50 μm de tantalio vaporizado sobre
un sustrato trabecular de carbono vítreo,
se consigue una espuma compuesta de un
98%-99% de tantalio y un 1%-2% de carbono.
Hemos encontrado trazas de carbono
contaminando la superfi cie de las trabéculas
de tántalo pero sin repercusión en cuanto a
compatibilidad de la estructura. Los poros formados
tienen forma dodecaédrica, con una
talla media de 550 μm. Hemos caracterizado
la porosidad según el método del desplazamiento
encontrando, frente a una porosidad
standard del 75%-80%, variaciones entre el
66% y el 88%, similares a las medidas por
Shimko y cols. (J Biomed Mat Res 2005).
Las propiedades mecánicas de este “metal
trabecular” van a depender, como en cualquier
caso, de la cantidad de materia constitutiva
del sistema y de su distribución, con
un alta correlación peso/resistencia y grosor
de las trabéculas de tantalio/resistencia. La
resistencia a la compresión de un sistema
con una porosidad del 80% y poros de 550
μm es de 71.2±0.86 MPa, inferior a la de otras
espumas metálicas como las constituidas por
titanio-niquel que resisten, en condiciones similares,
142.5±29.3 MPa. El módulo elástico
es, en cambio, muy parecido al del hueso
trabecular, 1.15±0.86 GPa del tantalio frente
a 1.08±0.86 GPa del hueso. La deformación
a la fractura es también muy similar entre
ambos materiales (8.1±1.8% del tantalio y
7.1±3.0% del hueso trabecular). Esta compatibilidad
mecánica del tantalio es una de las
incuestionables ventajas del sistema.
La otra gran ventaja es la gran susceptibilidad
a ser invadido por el hueso neoformado, demostrada
por Boby y cols. en 1999, que hace
que a 4 semanas haya sido ocupada el 47%
de la porosidad del sistema. y a 52 semanas
el 75% de la misma. Pero es que, además, a
esta osteoconductividad cabe añadirle posiblemente
una capacidad osteoinductiva por
la microtopografía de la superfi cie del sistema
(“señales insolubles” de Ripamonti, 1997). A
8 días de la implantación existe ya una deposición
de fosfato de calcio amorfo sobre el
tantalio, con nucleación temprana de cristales
de hidroxiapatita. La luz del sistema poroso
se ve reducidad en un 30% de promedio. La
resistencia al cizallamiento del la intercara
sistema poroso-hueso, con un coefi ciente
de fricción de 0,88, es muy importante en lo
inmediato concediendo una gran estabilidad
primaria al implante. Esta faculta que a las
4 semanas dicha resistencia sea de 18,5
MPa, expresando la estabilidad secundaria
alcanzada. La osteointegración es evidente,

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con un íntimo contacto hueso-implante, sin
intercara fi brosa, y produciéndose la rotura
a la extracción a nivel del hueso y no en la
interfaz hueso-tantalio, a los 3 meses.
Con todo ello se puede afi rmar que el tantalio
es un material prometedor como constitutivo
de implantes protésicos y así lo corrobora la
experiencia clínica tanto como recubrimiento
de implantes cotiloideos en artroplastias de
cadera, como de implantes tibiales en artroplastias
de rodilla.

Notas / Notes
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Notas / Notes
Miercoles, 29 de noviembre
Wednesday, 29th November
md
CADERA / HIP
Prótesis con conservación ósea: Resurfacing
Abordajes quirúrgicos: MIS y navegación
Cadera difícil y complicaciones de las artroplastias
Cadera de revisión
Hip prosthesis with bone stock conservation: Resurfacing
Surgical approach: MIS and navigation
Diffi cult hip and complications
Hip revision
Moderadores / Moderators: Jorge O. Galante, Hendrik P. Delport,
Cecil Rorabeck, Wayne Paprosky, Douglas A. Dennis
MIÉRCOLES / WEDNESDAY
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MIÉRCOLES / WEDNESDAY
100
08.15 - 10.45 h
CADERA / HIP
Prótesis con conservación ósea: Resurfacing
Hip prosthesis with bone stock conservation: Resurfacing
Moderador / Moderator: Jorge O. Galante
PATIENT SELECTION AND
SURGICAL TECHNIQUE
FOR HIP RESURFACING
P. Beaulé
Associate Professor
University of Ottawa, Canada
In recent years, there has been resurgence in
the interest of metal-on-metal surface arthroplasty
of the hip 1 as an alternative to total hip
replacement for the young and active adult 2 .
Concomitantly, ceramic on ceramic bearings
and new polyethylenes are being introduced
as promising technology to improve the
longevity of standard total hip replacements.
Although these technologies are being embraced
3,4 by many, the 10 year survivorship
of ceramic on ceramic total hips is relatively
low at 79-85% 5,6 , and the new polyethylenes
have only two year data 7 .
Similarly, the renewed interest in the clinically
proven low wear of the metal on metal bearing
8,9 combined with the capacity of inserting a
thin wall cementless acetabular component 10
has fostered the reintroduction of surface
arthroplasty of the hip. As in other forms of
conservative hip surgery i.e. pelvic osteotomies
11 and surgical dislocation 12,13 , patient
selection will help minimize complications 14
and the need for early reoperation.
METAL ON METAL SURFACE ARTHRO-
PLASTY OF THE HIP
There have been two recent publications
on the short term results of hybrid metal on
metal surface arthroplasty with a 94% to
99.8% survivorship at four years 25,26 . In both
series, patients returned to very high activity
level with a mean patient age for both series
of 48 years old. Amstutz and associates 25
identifi ed several variables putting patient
at risk for early failure: femoral head cysts,
patient height and previous hip surgery. In
contrast, Daniel and associates 26 emphasized
metallurgy and manufacturing of the metal on
metal bearing as the main determinants for
a well-functioning surface arthroplasty where
hot isostatic pressing and solution annealing
of the components were reported to be
unfavorable to the wear properties. 27 Based
on that assumption, a group of 186 hips were
excluded from their study 26 due to a sub-optimal
manufacturing process of the implant
which reportedly lead to a high incidence of
osteolysis and associated component loosening.
Unfortunately, no radiographic evaluation
was provided in their review making the
improvement in the manufacturing of the
components diffi cult to confi rm. In addition,
Nevelos and associates’ 28 recent analysis of
metal on metal bearings tested in hip simulators
found no infl uence of the manufacturing
process on the wear properties with the main
determinants for optimal wear performance
being relatively low radial clearances and a
high carbon content.
As with the introduction of cementless designs
in total hip replacements 29 , metal on
metal bearings is not the one answer to the
success of surface arthroplasty of the hip.
A Surface Arthroplasty Risk Index (SARI)14
was developed and based on a 6 point scor-

Notas / Notes
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MIÉRCOLES / WEDNESDAY
102
ing system (Table 1) with a score >3 representing
a 12 fold increase risk in early failure
or adverse radiological changes. In addition,
when Amstutz and associates25 reported on
the overall experience in the fi rst 400 hybrid
metal on metal SA, a SARI >3 had a survivorship
of 89% at four years versus 97% with a
score < 3.
Currently, the posterior approach is the most
commonly used for hip resurfacing. However,
as discussed in this issue by Nork and associates30
the choice of a surgical approach
for hip resurfacing must factor in different
anatomical considerations than when performing
a standard total hip replacement.
With preservation of the femoral head and
neck, issues such as vascularity and adequate
visualization with minimal trauma to
tissues and nerves must be considered10,30 .
For example, the choice of a surgical approach
compromising femoral head blood
supply10,30,31 and causing osteonecrosis could
lead to femoral loosening32 or femoral neck
fracture33 if the lesion is suffi ciently large. In
addition, because of its conservative nature
and goal to closely reproduce the normal
anatomy of the proximal femur positioning of
the implants may have a greater impact on
implant survivorship and patient function than
with a standard hip replacement.
In the 1982 OCNA issue on surface arthroplasty,
Hedley31 emphasized the importance
of maintaining femoral head vascularity when
considering intervention in early stages of arthritis
whilst in the more advanced stages an
intramedullary source would be suffi cient34 .
The discussion at that time was not so much
what surgical approach to use since most
were using a pure anterior35 or extracapsular
trochanteric osteotomy36 but can one safely
dislocate the native hip joint without causing
osteonecrosis. Subsequent retrieval analysis
papers of failed surface arthroplasty failed to
identify any major osteonecrotic segments. 37-
39 , however the massive granulomatous
reaction from the polyethylene wear debris
combined with bone resorption secondary
to implant micromotion did not leave much of
the bone at the implant interface intact. And
more importantly, most surgeons at that time
where performing hip resurfacing through
approaches which left the obturator externus
tendon intact protecting the branch of the medial
circumfl ex artery 40 . In addition, there is
recent evidence that the blood supply pattern
in advanced arthritis is not signifi cantly different
than in the non arthritic state 41 . Recent
work on arthritic femoral heads, presented
at the annual Orthopaedic Research Society
meeting in Washington, DC (February 2005)
demonstrated using laser doppler fl owmetry
that damage to the extraosseous blood supply
to the femoral head (retinacular vessels)
can cause a signifi cant decrease (greater
than 50%) in blood fl ow. Further followup and
research will be required before we can fully
assess the role of femoral head vascularity
on the clinical outcome of hip resurfacing,
however the choice of a surgical approach
which minimizes the risk of damaging the
blood supply to the femoral head need to
be strongly considered. This may become
even more crucial as we consider cementless
fi xation on the femoral side and earlier
intervention in the arthritic process to avoid
the development of femoral head cysts.
Finally, one must consider the underlying diagnosis
when evaluating a patient for surface
arthroplasty. In cases of dysplasia, acetabular
defi ciencies combined with the inability
of inserting screws through the acetabular
component may make initial implant stability
unpredictable. This deformity in combination
with a signifi cant leg length discrepancy or
valgus femoral neck could compromise the
functional results of surface arthroplasty, and
in those situations a stem type total hip replacement
may provide a superior functional
outcome 51 . Finally, the presence of a metal on
metal bearing leads to an increase in metal
ion release 9,52 . Consequently, because the
information on the systemic distribution of
metal ions and their interaction with living
cells is limited, patients with compromised
renal function and a history of metal sensitivity
are probably not good candidates for a

Notas / Notes
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MIÉRCOLES / WEDNESDAY
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metal-on-metal bearing 9,53 .
Table 1: The Surface Arthroplasty Risk Index
(SARI) 14
POINTS
Femoral Head Cyst >1cm 2
Patient Weight < 82kg 2
Previous Hip Surgery 1
UCLA Activity level >6 1
MAXIMUM SCORE 6
Reference List
1. Beaule, PE, and Amstutz, HC. Surface
Arthroplasty of the Hip Revisited: current
indications and surgical technique. In Hip
Replacement:current trends and controversies.,
p 261-297. Edited by R. J. Sinha.
New York, Marcel Dekker, 2002.
2. Sochart DH. Relationship of acetabular
wear to osteolysis and loosening in total
hip arthroplasty. Clin.Orthop.Rel.Res.
1999;363:135-50.
3. D’Antonio JA et al. New experience with
alumina-on-alumina ceramic bearings
for total hip arthroplasty. J Arthroplasty
2002;17:390-397.
4. Garino JP. Modern Ceramic-on-Ceramic
total hip systems in the United States. Clin.
Orthop. 2000;379:41-47.
5. Hamadouche M, et al. Alumina-on-alumina
total hip arthroplasty: a minimum 18.5year
follow-up study. J Bone Joint Surg.
2002;84A:69-77.
6. Bizot P et al Alumina-on-alumina total
hip prostheses in patients 40 years of
age or younger. Clin.Orthop.Rel.Res.
2000;379:68-76.
7. Heisel C, Silva M, dela Rosa M, Schmalzreid
TP. Short-Term in Vivo Wear of Crosslinked
Polyethylenes. J Bone Joint Surg.
2004;86A:748-51.
8. Sieber H-P, Rieker CB, Kottig P . Analysis
of 118 second-generation metal-on-metal
retrieved hip implants. J.Bone and Joint
Surg. 1999;81B:46-50.
9. Brodner W et al Serum Cobalt Levels after
metal-on-metal total hip arthroplasty. J
Bone Joint Surg. 2003;85A:2168-73.
10. Beaule PE. A soft tissue sparing approach
to surface arthroplasty of the hip.
Oper Tech Ortho 2004;14:16-18.
11. Trousdale RT et al Periacetabular and
intertrochanteric osteotomy for the treatment
of osteoarthrosis in dysplastic hips.
J.Bone Joint Surg.Am. 1995;77:73-85.
2. Ganz R et al Surgical dislocation of the
adult hip. A new technique with full access
to the femoral head and acetabulum without
the risk of avascular necrosis. J Bone
Joint Surg. 2001;83B:1119-24.
13. Beck M et al Anterior Femoroacetabular
Impingement. Part II. Midterm Results
of surgical treatment. Clin.Orthop.
2004;418:67-73.
14. Beaule PE et al. Risk factors affecting
outcome of metal on metal surface
arthroplasty of the hip. Clin.Orthop.
2004;418:87-93.
15. Beaule PE. Surface Arthroplasty of the
Hip: A Review and Current Indications.
Semin Arthroplasty 2004.
16 Amstutz HC et al Metal-on-Metal Hybrid
Surface Arthroplasty: Two to Six Year Follow-up.
J Bone Joint Surg. 2004;86A:28-
39.
17 Daniel et al. Metal-on-metal resurfacing
of the hip in patients under the age of 55
years with osteoarthritis. J Bone Joint
Surg. 2004;86B:177-84.
18 McMinn DJW. Development of Metal/
Metal Hip Resurfacing. Hip International
2003;13:S41-S53.
19 Nevelos J, Shelton JC, Fisher J. Metallurgical
considerations in the wear of metalon-metal
hip bearings. Hip International
2004;14:1-10.
20 Jones LC, Hungerford DS. Cement Disease.
Clin.Orthop. 1987;225:192-206.
21 Nork SE et al. Anatomic Considerations
for the choice of surgical approach for hip
resurfacing arthroplasty. Orthop Clin.North
Am.36(2 )pp163-70 2005.
22 Hedley AK. Τεχηνιχαλ χονσιδερατιονσ

Notas / Notes
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MIÉRCOLES / WEDNESDAY
106
ωιτη συρφαχε ρεπλαχεμεντ. Orthop Clin.
North Am. 1982;13:747-60.
23 Bell RS et al A study of implant failure
in the Wagner resurfacing arthroplasty.
J.Bone and Joint Surg. 1985;67A:1165-
75.
24 Amstutz HC, Le Duff MJ, Campbell PA.
Fracture of the neck of the femur after
surface arthroplasty of the hip. J Bone
Joint Surg. 2004;86A:1874-77.
25 Freeman MAR. Some anatomical and
mechanical considerations relevant to the
surface replacement of the femoral head.
Clin.Orthop. 1978;134:19-24.
26 Wagner H. Surface Replacement
Arthroplasty of the Hip. Clin.Orthop.
1978;134:102-30.
27 Amstutz HC et al Surface replacement of
the hip with the THARIES system. J Bone
Joint Surg. 1981;63A:1069-77.
28 Howie DW et al The viability of the
femoral head after resurfacing hip arthroplasty
in humans. Clin.Orthop.Rel.Res.
1993;291:171-84.
29 Campbell PA et al Viability of Femoral
Head treated with Resurfacing. Arthroplasty.
J Arthroplasty 2000;15:120-122.
30 Freeman MA, Bradley GW. ICLH surface
replacement of the hip. An analysis of
the fi rst 10 years. J.Bone Joint Surg.[Br.]
1983;65:405-11.
31 Gautier E, et al Anatomy of the medial circumfl
ex artery and its surgical implications.
J Bone Joint Surg. 2000;82B:679-83.
32 Beaule PE et al . Notching of the Femoral
Neck During Surface Arthroplasty of the
Hip.A Vascular study. Orthopaedic Research
Society 2005;Proceedings.
33 Beaule PE et al. Orientation of Femoral
Component in Surface Arthroplasty of the
Hip: A biomechanical and clinical analysis.
J Bone Joint Surg. 2004;86A:2015-21.
34 Jacobs et al. Cobalt and chromium concentrations
in patients with metal on metal
total hip replacements. Clin.Orthop.Rel.
Res. 1996;329S:S256-S263.
35 Campbell et al. Biologic and tribologic
considerations of alternative bearing sur-
faces. Clin.Orthop. 2004;418:98-111.
RESURFACING THA – AN
EMERGING TECHNOLOGY
C. H. Rorabeck, MD
Health Sciences Centre, Ontario, Canada
Historically, the results of surface replacement
have been poor; however, one needs
to examine the reasons for this. The sockets
were thin and made of high density polyethylene
and were cemented. They frequently
loosened. Also, avascular necrosis of the
femoral head leading to collapse occurred.
This was often related to patient selection,
surgical technique or combination thereof.
The most unique problem identified with
surface replacement was fracture of the neck
of the femur which could occur with notching.
Thus, in summary, during the 1970’s
and 1980’s resurfacing was associated with
a small incidence of femoral neck fracture, a
small incidence of collapsed femoral heads
and a major problem with large head metal
polyethylene wear leading to massive polyethylene
induced osteolysis, cup loosening
and failure.
Newer hip resurfacing designs (e.g. BHR) will
eliminate many of these problems because
of the large head metal on metal bearing
surfaces. Metal/metal bearings have been
around for almost 30 years and it is clear that
osteolysis, with metal on metal, is very rare
and it equally clear that large heads, provided
polar contact is used, work very well. Thus,
the newer metal-metal resurfacings allow the
surgeon to insert the acetabulum cementless
and the newer generation instrumentation
has enabled the surgeon to insert the femoral
component in a reproducible manner with
minimal risk to notching etc.
The UK experience with the BHR resurfacing
hip began in 1997 and at 5-years demonstrat-

Notas / Notes
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MIÉRCOLES / WEDNESDAY
108
ed no hetertopic ossifi cation, no radiolucent
lines, and no cup migration; however, there
was a question of minor migration of the
femoral component or perhaps stress shielding
of the proximal femur. Subsequently,
independent RSA studies demonstrated, out
to 24 months, minimal change in position of
the femoral component and the acetabular
component. Similarly, dexa scan data have,
if anything, shown an improvement in bone
mineral density in Zone 7, when compared to
conventional total hip replacement.
Is the risk for metal ion exposure to patients
with a metal-metal resurfacing THR any different
from contemporary metal-metal THR?
While whole blood levels of cobalt and chromium
are elevated with metal-metal articulations,
nonetheless, these levels appear to be
acceptable and in some cases, have been
shown to diminish with time.
What are the clinical results of contemporary
metal-metal resurfacing THR? Some of
the earlier reported series indicated higher
revision rates at 5-years than traditional hip
replacement. For example, McMinn (1996)
reported a 4% revision rate at 5 years in 235
hips. Similarly, Amstutz had a similar revision
rate at 3-5 years using his metal-metal
resurfacing device.
More recent data, however, would suggest
that while failures of resurfacing hip arthroplasty
can occur, nevertheless, the incidence
of fracture of the femoral neck has been reduced
substantially, although it will never be
completely eliminated. McMinn, reporting his
experience of 2,385 Birmingham THR’s, notes
27 patients needed to be revised at a 5-year
follow up. These included 10 for femoral neck
fracture and a further 8 for either AVN or collapse
of the femoral head. Thus, while these
complications have not been totally eliminated
in metal-metal resurfacing THR, nonetheless,
the incidence is extremely low. Similarly, data
from the Australian Joint Replacement Registry
would indicate the incidence of femoral
neck fracture to be less than 1%.
Clearly, patient selection is important for
resurfacing arthroplasty. In our Center we
reserve the operation for patients 60 years of
age or younger with normal bone stock and
do not recommend it for patients with infl ammatory
arthritis.
In conclusion, contemporary results in metalmetal
resurfacing replacement have been
excellent and it is clearly a bone conserving
operation. In prospective trials, the mid-term
results of metal-metal resurfacing are at least
as good as traditional THR.
While the potential for neck fracture with
resurfacing athroplasty is present, a review
of the literature indicates that if it is going
to occur it is most likely to do so within the
fi rst few months. Metal-metal resurfacing
arthroplasty of the hip is best indicated today
in non-infl ammatory arthritis and in patients
of less than 60 or individuals with a normal
dexa scan.
References:
Back D, Dalziel R, Young D, Shimmin A. Early
results of primary Birmingham resurfacings.
An independent prospective study of the fi rst
230 hips. J Bone Joint Surg Br (2005 Mar)
87(3):324-9
Ebied A, Jouneaux SF, Pope JA. Hip resurfacing
arthroplasty: The Liverpool experience.
International Conference Engineers and Surgeons
– Joined at the Hip (2002 June)
de Smet KA, Pattyn C, Verdonk R. Early
results of primary Birmingham hip resurfacing
using a hybrid metal-on-metal couple. Hip
International (2002) 12:2:158-162.
Glyn-Jones S, Gill HS, McLardy-Smith P, Murray
DW. Roentgen stereophobgrammetric
analysis of the Birmingham hip resurfacing
arthroplasty: A 2-year study. J Bone Joint
Surg Br (2004 March) 86B:172-6.

Notas / Notes
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110
Itayem RA, Arndt A, Nistor L, McMinn D,
Lundberg A. Stability of the Birmingham
hip resurfacing arthroplasty at 2 years: A
radiostereophobgrammetric analysis study.
J Bone Joint Surg Br (2005 February)
87(2):158-62.
Kishida Y, Sugano N, Nishi T, Miki H, Yamaguchi
K, Yoshkawa H. Preservation of bone
mineral density of the femur after surface
replacement of the hip. J Bone Joint Surg Br
(2004 March) 86B:185-89.
Treacy RB, McBryde CW. Pynsent PB. Birmingham
resurfacing arthroplasty. A minimum
follow up of 5 years. J Bone Joint Surg BR
(2005 February). 87(2): 167-70
Oswestry Worldwide. FDA Review Memo,
page 59.
FEMORAL HEAD/
NECK OFFSET AND
HIP RESURFACING
P. Beaulé
Head Adult Reconstruction
Division of Orthopaedic Surgery
University of Ottawa, Canada
The main advantages of hip resurfacing are
preservation of the proximal femoral bone
stock as wells as enhanced hip stability. Conversely,
because the femoral head/neck junction
is preserved, patients maybe at greater
risk of impingement leading to abnormal wear
patterns and pain. We sought to investigate
the femoral head/neck offset in hips undergoing
resurfacing arthroplasty.
Using standardized radiographs both
anteroposterior and cross table lateral, we
measured and compared the femoral head/
neck offset measured as the offset ratio in
sixty-three hips that had a metal on metal
hip resurfacing with fi fty-six hips present-
ing with nonarthritic hip pain secondary to
femoroacetabular impingement diagnosed
with three-dimensional computer tomography
measuring the alpha angle. In the nonarthtitic
hips, the average offset ratio was 0.13 with
the offset ratio being negatively correlated to
an increasing alpha angle (r=-0.40, p=0.002).
An offset ratio less than or equal to 0.15 had
a 9.5 fold increased relative risk of having an
alpha angle greater than 50.5°. The average
pre-operative offset ratio for the resurfacing
group was not signifi cantly different to the
nonarthritic group (p=0.326). A majority of
hips undergoing hip resurfacing hips (36 out
o 63) had offset ratio less than or equal to
0.15. Those hips had a greater correction in
the offset ratio post operatively as compared
to the rest of the group (p=0.003). A majority
of hips undergoing hip resurfacing have an
abnormal femoral head/neck offset which is
best assessed in the axial plane. Recognition
of this deformity with the cross table lateral
radiograph permits its correction at the time
of the resurfacing
arthroplasty.
References
(1) Beaulé PE, Dorey FJ, LeDuff MJ, Gruen
T, Amstutz HC. Risk factors affecting
outcome of metal on metal surface
arthroplasty of the hip. Clin Orthop
2004;418(418):87-93.
(2) Amstutz HC, Beaulé PE, Dorey FJ, Campbell
PA, Le Duff MJ, Gruen TA. Metal-on-
Metal Hybrid Surface Arthroplasty: Two
to Six Year Follow-up. J Bone Joint Surg
2004;86A(1):28-39.
(3) Daniel J, Pynsent PB, McMinn DJW.
Metal-on-metal resurfacing of the hip
in patients under the age of 55 years
with osteoarthritis. J Bone Joint Surg
2004;86B(2):177-84.
(4) Beaulé PE, Amstutz HC. Surface Arthroplasty
of the Hip Revisited: current indications
and surgical technique. In: Sinha RJ,
editor. Hip Replacement: current trends
and controversies. New York: Marcel
Dekker; 2002. p. 261-97.

Notas / Notes
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(5) Treacy R, Pynsent P. Birmingham Hip
Resurfacing arthroplasty. A minimum follow-up
of fi ve years. J Bone Joint Surg
2005;87B(2):167-70.
(6) Black DL, Dalziel R, Young D, Shimmin
A. Early results of primary Birmingham Hip
Resurfacings. An independent prospective
study of the fi rst 230 hips. J Bone Joint
Surg 2005;87B(3):324-9.
(7) Beaulé PE, Antoniades J. Patient Selection
and Surgical Technique for Surface
Arthroplasty of the Hip. Orthop Clin North
Am 2005;36(2):177-85.
(8) Beaulé PE, Lee J, LeDuff M, Dorey FJ,
Amstutz HC, Ebramzadeh E. Orientation
of Femoral Component in Surface
Arthroplasty of the Hip: A biomechanical
and clinical analysis. J Bone Joint Surg
2004;86A(9):2015-21.
(9) Shimmin A, Back D. Femoral neck fractures
following Birmingham hip resurfacing.
A national review of 50 cases. J Bone
Joint Surg 2005;87B(3):463-4.
(10) Silva M, Lee KH, Heisel C, dela Rosa M,
Schmalzried TP. The Biomechanical Results
of Total Hip Resurfacing Arthroplasty.
J Bone Joint Surg 2004;86A(1):40-1.
(11) Loughead JM, Chesney D, Holland JP,
McCaskie AW. Comparison of offset in
Birmingham hip resurfacing and hybrid
total hip arthroplasty. J Bone Joint Surg
2005;87B(2):163-6.
(13) McGrory BJ, Morrey BF, Cahalan TD,
An K.-N., Cabanela ME. Effect of femoral
offset on range of motion and abductor
muscle strength after total hip arthroplasty.
J Bone Joint Surg Br 1995;77B(6):865-9.
(14) Ito K, Minka-II MA, Leunig S, Werlen S,
Ganz R. Femoroacetabular impingement
and the cam-effect. J Bone Joint Surg
2001;83B(2):171-6.
(15) Eijer H, Leunig M, Mahomed N, Ganz R.
Cross-table lateral radiographs for screening
of anterior femoral head-neck offset in
patients with femoro-acetabular impingement.
Hip International 2001;11(1):37-
41.
(16) Beaulé PE, Zaragoza EJ, Motamedic K,
Copelan N, Dorey, .J. Three-dimensional
computed Tomography of the hip in the assessment
of Femoro-Acetabular Impingement.
J Orthop Res 2005;23(6):1286-92.
(20) Notzli HP, Wyss TF, Stoecklin CH, Schmid
MR, Treiber K, Hodler J. The contour fo the
femoral head-neck junction as a predictor
for the risk of anterior impingement. J Bone
Joint Surg 2002;84B(4):556-60.
(21) Ganz R, Parvizi J, Leunig M, Siebenrock
KA. Femoroacetabular Impingement: a
cause for osteoarthritis of the hip. Clin
Orthop 2003;417:112-20.
(22 Murray RO. The aetiolofy of primary
osteoarthritis of the hip. Br J Radiol
1965;38:810-24.
(23) Stulberg SD, Cordell LD, Harris WH,
Ramsey PL, MacEwen GD. Unrecognized
childhood hip disease: a major cause of
idiopathic osteoarthritis of the hip. In: Amstutz
HC, editor. The Hip, Proceedings of
the Third Open Scientifi c Meeting of the
Hip Society.St. Louis: C.V. Mosby; 1975.
p. 212-28.
(24) Harris WH. Etiology of osteoarthritis of
the hip. Clin Orthop Rel Res 1986;213:20-
33.
(26) Ganz R, Gill TJ, Gautier E, Ganz K, Krugel
N, Berlemann U. Surgical dislocation of
the adult hip. A new technique with full access
to the femoral head and acetabulum
without the risk of avascular necrosis. J
Bone Joint Surg 2001;83B(8):1119-24.
(27) Beaulé PE. A soft tissue sparing approach
to surface arthroplasty of the hip.
Oper Tech Ortho 2004;14(4):16-8.
(32) D’Lima DD, Urquhart AG, Buehler KO,
Walker RH, Colwell CWJ. The effect of the
orientation of the acetabular and femoral
components on the range of motion of the
hip at different head-neck ratios. J Bone
Joint Surg 2000;82A(3):315-21.
(33) Amstutz HC, Markolf KL. Design features
in total hip replacement. In: Harris WH,
editor. The Hip Society. Proceedings of
the second open scientifi c meeting. ed.
St. Louis: 1974. p. 111-24.
(34) Chandler DR, Glousman R, Hull D, Mc-

Notas / Notes
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Guire PJ, Kim IS, Clarke IC, et al. Prosthetic
hip range of motion and impingement.
The effects of head and neck geometry.
Clin Orthop 1982;186:284-91.
(35) Amstutz HC, Lodwig RM, Schurman DJ,
Hodgson AG. Range of motion studies
for total hip replacements. A comparative
study with a new experimental apparatus.
Clin Orthop 1975;111:124-30.
(36) Scifert CF, Brown TD, Pedersen DR,
Callaghan JJ. A fi nite element analysis of
factors infl uencing total hip dislocation.
Clin Orthop 1998;355:152-62.
(37) Howie DW, McCalden R, Nawana RW,
Costi K, Pearcy MJ, Subramanian C. The
long-term wear of retrieved McKee-Farrar
Metal-on-metal total hip prostheses. J
Arthroplasty 2005;20(3):350-7.
(39) Zahiri C, Schmalzried T, Ebramzadeh E,
Szuszczewicz E, Salib D, Kim C, et al. Lessons
learned from loosening of the McKee-
Farrar metal-on-metal total hip replacement.
J Arthroplasty 1999;14(3):326-32.
(40) Klapperich C, Graham J, Pruitt L, Ries
MD. Failure of a Metal-on-Metal Total Hip
Arthroplasty from Progressive Osteolysis.
J Arthroplasty 1999;14(7):877-81.
(53) Wiadrowski TP, McGee M, Cornish BL,
Howie DW. Peripheral wear of Wagner resurfacing
hip arthroplasty acetabular components.
J Arthroplasty 1991;6(2):103-7.
(54) Bartz RL, Noble PC, Kadakia NR, Tullos
HS. The effect of femoral component
head size on posterior dislocation of
the artifi cial hip joint. J Bone Joint Surg
2000;82(9):1300-7.
(55) Mardones RM, Gonzalez C, Chen Q,
Zobitz M, Kaufman KR, Trousdale RT.
Surgical Treatment of Femoroacetabular
Impingement: Evaluation of the Effect of
the Size of the Resection. J Bone Joint
Surg 2005;87Α(2):273-9.
HOW TO CEMENT THE
FEMORAL HEAD IN TOTAL
HIP RESURFACING
H. P. Delport
Head Department of Orthopaedics.
AZ Wassland Sint Niklaas. Belgium
Although our mid-term clinical results are
promising, 7 hips out of a series of 602
required a revision, of which 5 for early
fracture.
These cases raised our concern and therefore
we have analysed the retrieved specimens
in cooperation with Prof M Morlock
from Hamburg. Femoral components were
sectioned allowing inspection of the bonecement
interface.
Despite the component being designed to
have a 0,5 mm space for the cement mantle,
the thickness of this layer always was greater.
The cancellous bone always showed overpenetration
of cement and the cysts always
were fi lled with cement.
In all specimens some degree of necrosis
was observed.
These fi ndings correspond to the study of Pat
Campbell et al to be published in CORR.
We realised that this technically diffi cult procedure
puts the femoral neck at risk. Attention
to technical details as the thickness of the
cement mantle and the amount of cement
penetration is important. Uncovered reamed
bone is a weak point. Extra pressure to seat
the implant can cause fracture.
Reduction of the temperature at the bonecement
interface as proposed by Ritchie Gill
and K. De Smet (to be published JBJS-Br)
seems to be very important.
We present some techniques to reduce possible
damage to the bone during cementing
a hip resurfacing.

Notas / Notes
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CAUSE AND PREVENTION
OF NECK FRACTURES IN
HIP RESURFACING
P. Beaulé
Head Adult Reconstruction
Division of Orthopaedic Surgery
University of Ottawa, Canada
The reintroduction of hip resurfacing has
been fostered by the introduction of metal
on metal bearing. Early results have been
promising both in the short and medium term,
however although relatively low at 1-2%, the
occurrence of a femoral neck fracture represents
a signifi cant disadvantage to a stem
type total hip replacement.
The occurrence of a femoral neck fracture is
multifactorial in its etiology where a certain
threshold of the bony structural integrity must
be reached for it to occur. Some of these factors
include damage to the vascular supply
to the femoral head by surgical approach,
damage to the retinacular vessels, and over
cement penetration leading to thermal necrosis
of the bone.
There are also patient factors such osteoporosis
which may permit over cement
penetration as well as presence of femoral
head cysts. Finally, some guidelines will be
provided to minimize those risks in respect
to femoral component positioning i.e. relative
valgus and choice of surgical exposure i.e.
preserving femoral head vascularity.
RECOMMENDED READING:
ORTHOPEDIC CLINICS OF NORTH AMER-
ICA: APRIL 2005 VOL 36 NO. 2 entitled Surface
Arthroplasty of the Hip Revisited edited
by Leunig and Beaulé.
Notching of the Femoral Neck During Hip
Resurfacing. A vascular study.
PE Beaulé, P Campbell, R Hoke and F. Dorey
JBJS 88B Vol 1, pp 35-39, 2006.
Femoral Head Blood Flow during Hip Resurfacing.
PE Beaulé, P Campbell, Paul Shim
Clin Orthop and Rel Res (E Pub Sept 28
2006)
Vascularity of the Arthritic Femoral Head and
Its Implications for hip resurfacing.
PE Beaulé, P Campbell, Z Lu, Ganz K, Beck
M, Leunig M and Ganz R.
JBJS Am Suppl December 2006
SURFACE ARTHROPLASTY
OF THE HIP: RESULTS OF
MULTICENTER TRIALS
V. M Goldberg, M.D
Department of Orthopaedics
Case Western Reserve University
University Hospitals of Cleveland
Cleveland, Ohio, USA
Hip resurfacing arthroplasty using metal on
metal surfaces has become another option
for the young patient with significant hip
arthritis. Surface replacement arthroplasty
(SRA) provides enhancement to the lifestyle
of young active patients while conserving
bone to make future revisions easier. There
are a number of additional advantages to this
procedure. They include: an increased range
of motion because of the large diameter femoral
head, a more wear resistant couple compared
to traditional surfaces, and a signifi cant
reduction of hip dislocation because of the
large femoral head diameter. A large femoral
head approximating normal hip anatomy may
provide patients an opportunity for enhanced
kinematics with improved function.
The original designs used in resurfacing hip
replacements were generally not successful

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118
because of the thin polyethylene acetabular
component. The large diameter metal heads
coupled with polyethylene cups resulted in increased
volumetric wear compared to 28mm
diameter femoral heads articulating with
polyethylene. The increased wear with subsequent
osteolysis led to implant loosening.
Since there was no centering femoral stem,
unsatisfactory femoral positioning was more
prevalent. The development of improved
manufacturing methods and metal-on-metal
articulations have provided an opportunity
to once again explore resurfacing hip arthroplasty
as a treatment approach to the younger
arthritic patient. Metal-on-metal surfaces now
are manufactured with tighter tolerances, better
surface fi nishes and improved clearances
that make it a useful articulation for SRA. A
greater range of sizes with 2mm increments
for better matching the patients anatomy
has enhanced the opportunity for improved
outcomes.
Although the early results of these new
designs of metal-on-metal surface replacements
are generally excellent, a number
of signifi cant problems still remain. These
complications include: femoral neck fracture
and femoral loosening, and the long-term issue
of metal ion release from the surface of
the metal-on-metal articulation. Early data
focusing on the metal ion problem, indicate
that there is a signifi cantly increased blood
and tissue level of both cobalt and chromium,
however, the clinical implications of these
elevated metal ion levels has yet to be delineated.
Patient selection still remains controversial.
The ideal patient for a hip resurfacing
procedure is usually a young, active patient
with osteoarthritis without major deformities
and excellent proximal femoral bone quality.
Contraindications include elderly patients with
poor femoral bone, metal hypersensitivity and
impaired renal function. The role of surface
replacement arthroplasty in inflammatory
arthritis remains controversial. Large areas
of avascular necrosis or large cysts in the
femoral head may preclude the application
of SRA.
Our early experience with SRA of the hip is
with the Conserve Plus Prosthesis® (Wright
Medical Technologies), performed in seventy-eight
consecutive patients. Seventy-eight
replacements were performed and followed
six to fi fty-two months (mean 30 months).
The procedure was approved by the hospital
institutional review board. The indications for
the procedure included a younger age group
with a high level of activity. All patients were
Charnley Class A. All of the patients except
one with avascular necrosis had a diagnosis
of osteoarthritis. There were 57 males and
21 females between the age of 29 and 65.
The Conserve Plus® acetabular shell is
170 degrees and nearly hemispherical. It is
manufactured from a high carbon cast cobalt
chromium molybdenum steel conforming to
ASTM F75 standards. The exterior surface
of the acetabular component has sintered
beads ranging from 50-150 microns in diameter
for cementless fi xation. The one piece
acetabular shell is available in a 3.5mm
thin shell and 5mm thick shell. The femoral
component is greater then a hemisphere
(208 degrees) which enables coverage of
all the reamed bone by the component and
maintains the length of the femoral head and
neck. The surface fi nish is approximately
0.008 micrometers. The component has
a short metaphyseal stem and permits a
cement mantle with an average thickness
of 1.25mm around the femoral head. The
components are available in 2mm increments
(the acetabular sizes are 46 to 64 mm, the
femoral head sizes 36 to 54 mm).
The surgical technique has been previously
described and uses a posterior approach. All
patients were managed with adjusted lowdose
Warafi n® for 3 weeks and prophylactic
antibiotics (Kefzol®). Crutches with partial
weight bearing were used for 6 weeks and
a cane thereafter, until the patients did not
have a signifi cant limp. Sports usually were
permitted at four months post-operatively.

Notas / Notes
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All patients were followed clinically prospectively
using the Harris Hip Score (HSS) and
radiographs were evaluated at each follow-up
visit. Patients were seen at six weeks, three
months, six months, one year and yearly
thereafter. None of the patients were lost
to follow-up.
There were fi ve failures early in the clinical
experience that required revision to a
total hip replacement. Only one acetabular
component loosened early in a patient with
signifi cant osteoarthritis secondary to developmental
dysplasia. There were three neck
fractures and one femoral loosening. All were
seen during the fi rst eighteen months of the
study in the initial thirty hips. There have
been no failures in the last thirty-three hips.
The average HHS improved from 51 (30-70)
to 99 (85-100) in the non-revised patients.
The only complication in addition to the failures
was heterotopic ossifi cation (Grade II
or III) in four hips. Radiographic lucent lines
(

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The new generation of resurfacing devices
have been widely used, and the early results
are encouraging but long term follow-up
is still needed. The concept is particularly
suitable for treatment of young active patients,
in whom traditional hip replacement
might require revision in less than ten years.
Resurfacing is challenging, the devices are
highly engineered and should be precisely
implanted. They may not be as surgically
forgiving as conventional replacements.
Concerns remain about the level of metal ions
released from such devices, but there is no
defi nite evidence of harmful effects.
RESURFACING VERSUS
TRADITIONAL ARTHROPLASTY
J. Timperley
Princess Elisabeth Orthopaedic
Hospital, Exeter, Great Britain

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11.15 - 12.45 h
CADERA / HIP
Abordajes quirúrgicos: MIS y navegación
Surgical approach: MIS and navigation
Moderador / Moderator: Hendrik P. Delport
THE RATIONALE, SURGICAL
TECHNIQUE AND RESULTS
OF USING SHORT,
METAPHYSEAL IN STEMS
INTHA. SHORT STEMS -
THE NEXT GENERATION
OF IMPLANTS IN THA
D. Stulberg
Northwestern University Feinberg School
of Medicine - Chicago, Illinois, USA
QUO VADIS MIS?
J. Galante, MD
Rush Arthritis & Orthopaedic Institute
Illinois, USA
Some of the most notable technological
developments introduced in Total Hip Replacement
over the last three decades include;
cementless fi xation for the femur and
acetabulum, wear resistant articular couples
and minimally invasive techniques.
Minimally Invasive Techniques are used
routinely today in most orthopedic centers.
There are many arguments that support the
use of this principle in total hip replacement.
Less tissue damage and consequently diminished
postoperative pain, lower incidence of
per operative complications, shorter hospital
stay, faster rehabilitation, earlier return to an
active and productive lifestyle, a smaller more
aesthetically appealing surgical scar.
A number of surgical approaches are being
used including the straight lateral, posterolateral,
a modifi ed Watson- Jones, an anterior
and a two incision technique. There has been
a great deal of controversy regarding the
relative advantages of each one of these approaches
and in particular of the two incision
technique. Some surgeons have reported
excellent results with it while others have
seen a large number of complications and no
difference in function when compared to the
other approaches. This is a procedure that
is still in evolution. Continuing developments
in guidance systems, instrumentation and
prosthetic devices are required.
The rapid rehabilitation experienced with
all minimally invasive techniques is not only
related to the surgical exposure. The rehabilitation
protocol and the management of pain
both before and after the surgical procedure
play an essential role in allowing early function
and a prompt hospital discharge.
We have entered a new era in THR surgery
where rapid rehabilitation plays a crucial
role and the overall plan of patient manage-

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MIÉRCOLES / WEDNESDAY
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ment is as important as the type of surgical
exposure used.
MIS THA: POSTERIOR
APPROACH
D. A. Dennis, M.D.
Adjunct Professor, Dept. of Biomedical
Engineering, University of Tennessee
Assistant Clinical Professor, University
of Colorado Health Sciences Center
Clinical Director, Rocky Mountain Musculoskeletal
Research Laboratory
Denver, Colorado, USA
1. Goals of Total Hip Arthroplasty (THA)
a. Restore Normal Function
i. Restore Hip Biomechanics
1. Offset / Leg Length
b. Eliminate Disabling Pain
c. Long Term Durability
i. Reduced Wear
ii. Long Term Fixation
d. Rapid Rehabilitation
i. Early Mobilization
ii. Multimodal Analgesia Program
1. Pre-emptive Analgesia
2. Local Injection
3. Peripheral Nerve Blocks
iii. Limit Soft Tissue Disruption
2. Minimally Invasive THA Approaches
a. Anterior
b. Anterolateral
c. Posterior
d. Two Incision Techniques
i. Anterior & Transgluteal
3. Minimal Invasive Posterior Approach
a. Advantages
i. Familiar to Most Surgeons
ii. Reproducible
iii. Minimizes Abductor Mechanism Damage
1. Facilitates Rapid Functional Return
iv. Specialized Equipment Not Required
1. O.R. Tables / Positioners / Intraoperative
Fluoroscopy
b. Surgical Techniques
i. Skin Incision
1. As Long As Necessary (9-12 cm In
Most)
2. Flex Hip 80º
3. Place Incision Parallel With Femur
Beginning 1-2 cm Distal To Vastus
Lateralis Tubercle and Extend
Proximally
a. TECHNICAL TIP: Extending Incision
Distally Facilitates Acetabular Reaming
Whereas Extending Proximally Eases
Femoral Preparation.
ii. External Rotator Release / Posterior
Capsulotomy
1. Incise Traversely Along Superior
Border of Piriformis Then Distally
Along Posterior Border of Greater
Trochanter
a. Preserve Quadratus Femoris
b. Detached Capsule / Rotators Tagged
With 5-Ethibond Suture For Later Repair
c. Preserve Ischiofemoral Ligament (Aids
Postoperative Stability)
iii. Acetabular / Femoral Preparation /
Implantation
iv. Anatomic Capsular / Rotator Repair
4. Clinical Results
i. Data Contradictory
1. Berger, et al, CORR, 2004
a. Quicker Return To Normal Function
b. Narcotics Discontinued By 6 Days
c. No Increased Complications
2. Wright, Sculco, et al, J. Arthroplasty,
2004
a. ↓ Length of Stay
b. Slightly Higher Clinical Scores (
p=0.042)
c. No Increased Complications
3. deBeer, et al, J. Arthroplasty, 2004
a. No Differences In Operative Time,
Blood Loss, Transfusion Requirements,
or Length of Stay
b. Increased Risk (With MIS Tech-

Notas / Notes
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MIÉRCOLES / WEDNESDAY
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niques) of Wound Complication,
Acetabular Component Malposition,
Poor Femoral Component
Fit / Fill
4. Archibeck & White, CORR, 2004
a. Two-Incision Technique
b. 851 Cases Performed By 159 Surgeons
Trained In The Technique
c. Complications Did Not Decrease As
More Experience Gained
d. 27 Nerve Palsies (3.2%)
e. 35 Femoral Neck Fractures (4.1%)
f. 11 Femoral Shaft Fractures (1.3%)
g. 9 Greater Trochanteric Fractures
(1.1%)
h. 7 Femoral Cortical Perforations
(0.8%)
i. Therefore, 62 Cases Of Femoral Fracture
Or Perforation (7.3%)
5. Pagnano, M. & Trousdale, Hip Society,
2005
a. Measured Muscle Damage Following
MIS THA With Two-Incision Vs.
Mini-Posterior Approaches
b. Substantial Damage To Abductor
Musculature Found In Both Approaches
(Greater With The
Two-Incision Approach)
5. Relative Contraindications
a. Substantial Obesity
b. Previous Hip Surgery / Retained Hardware
c. Large Muscular Males
i. Large Gluteal Muscles
ii. Tight Iliotibial Band
d. Severe Deformity
i. DDH / High Grade SCFE / Proximal
Femoral Deformity
ii. Severe Acetabular Protrusio
iii. Marked Preoperative Flexion and External
Rotation Contractures
6. Summary
a. Mini-Posterior Approaches Offer Potential
For Reduced Soft Tissue Dissection and
Rapid Recovery
b. Technically More Demanding
c. Rigid Fixation and Accurate Implant Positioning
Remain Paramount
d. Always Focus More On The 15 Year, NOT
THE 15 DAY RESULT.
Bibliography
1. deBeer J, Petruccelli D, Zalzal P, Winemaker
MJ: Single-incision, minimally invasive
total hip arthroplasty: length doesn’t matter.
J. Arthroplasty, 19(8):945-50, 2004.
2. Timm S: Minimally invasive total hip arthroplasty:
what is it all about? J Contin
Educ Nurs, 35:246-6, 2004
3. Dorr LD: Comment on: The appeal of
mini-incision. Orthopedics, 27(9):937-8,
2004.
4. Barrack RL: Comment on: The mini-incision:
occasionally desirable, but rarely
necessary. Orthopedics, 27(9):937-8,
2004.
5. Siguier T, Siguier M, Brumpt B: Mini-incision
anterior approach does not increase
dislocation rate: a study of 1037 total hip
replacements. Clin Orthop. 426:164-73,
2004.
6. Wright JM, et al.,: Mini-incision for total
hip arthroplasty: a prospective, controlled
investigation with 5-year follow-up evaluation.
J. Arthroplasty 19(5):538-45, 2004.
7. Woolson ST, Mow CS, Syquia JF, Lannin
JV, Schurman DJ: Comparison of primary
total hip replacements performed with
a standard incision or a mini-incision. J
Bone J Surg Am. 86-A: 1353-8, 2004.
8. Hungerford DS: Comment on: Minimally
invasive total hip arthroplasty: in opposition.
J. Arthroplasty, 19(4 Suppl 1) 78-80,
2004.
9. Nakamura S, Matsuda K, Arai N, Wakimotot
N, Matsushita T: Mini-incision posterior
approach for total hip arthroplasty. Int
Orthop. 28(4): 214-7, 2004.
10. Digioia AM 3rd, Blendea S, Jaramaz B,
Levinson TJ: Less invasive total hip arthroplasty
using navigational tools. Instr.
Course Lect 53:157-64, 2004.
11. Berger RA: The technique of minimally
invasive total hip arthroplasty using the

Notas / Notes
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MIÉRCOLES / WEDNESDAY
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two-incision approach. Instr Course Lect.
53:149-55, 2004.
12. Lester DK, Helm M: Mini-incision posterior
approach for hip arthroplasty. Orthop
Traumatol 4:245-253, 2001.
13. Archibeck MJ, White RE Jr: Learning
curve for the two-incision total hip replacement.
CORR 429:232-8, 2004.
14. Pagnano M and Trousdale RT: Muscle
damage after total hip arthroplasty done
with the two-incision and mini-posterior
techniques. Presented at the Hip Society
Winter Meeting, Washington, D.C., Feb.
2005.
MIS AND HIP RESURFACING
M. Menge
St. Marienkrankenhaus. Orthopedic
Department, Luwigshafen, Germany
In younger and active patients with severe
osteoarthritis of the hip resurfacing arthroplasty
has become a promising alternative
to standard total hip replacement. As the
preserved femoral head interferes with the
preparation of the acetabulum resurfacing
arthroplasty techniques mostly require a
broader approach. Especially for the navigation
of the femoral device with special gauges
the incision has to be extended inferiorly. But
even with a longer scar and extended soft tissue
incision there still were problems affl icting
the outcome of the operation. In comparison
to a standard hip replacement there are new
risks of early neck fracture (notching, neck
lengthening, high impact preparation, and
blood supply), late fracture due to AVN, and
metal hypersensitivity. As the preservation
of the natural neck reduces the range of
movement the orientation of the socket will
be critical.
In spite of these problems resurfacing of the
hip in a minimal invasive technique is possible
for an experienced surgeon without the risk
of malposition of the implants or increasing
the rate of side effects. The technique by a
dorsal approach without special instrumentation
will be described step by step for the
IconR resurfacing arthroplasty. All anatomical
structures are visible at the corresponding
preparation steps and there is no higher risk
for the patient.
As a result the advantages of MIS can be obtained
in resurfacing arthroplasty: Less blood
loss, shorter procedure, less postoperative
pain and faster recovery. Last but not least the
patients will be pleased by a shorter scar.

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12.45 - 17.15 h
CADERA / HIP
Cadera difícil y complicaciones de las artroplastias
Diffi cult hip and complications
Moderadores / Moderators: Cecil Rorabeck, Wayne Paprosky
MANAGEMENT OF
THE PAINFUL HIP OF
THE YOUNG ADULT
R. Ganz
Orthopädische Universitätsklinik
Balgrist, Zürich, Switzerland
The vaste majority of hip symptoms in young
adults can be attributed to acetabular dysplasia
or femoroacetabular impingement.
The best treatment fort he hip with acetabular
dysplasia is a reorientation procedure.
Frequently the insuffi ciently shaped anterior
head-neck contour needs to be additionally
corrected to avoid secondary impingement
even with a perfectly corrected acetabulum.
This is even more importand in a borderline
dysplastic acetabulum which is symptomatic
from impingement even before surgery; Radial
arthro-MRI may be helpful in the precise
evaluation of such hips. The result of a reorientation
procedure depends on the achieved
spatial positioning of the acetabulum, on the
joint congruency but also on the amount of
joint damage at the time of surgery. Hips
without a labral lesion have a better longterm
prognosis.
The treatment of femoroacetabular impingement
focuses on improving the clearence for
hip motion. On the acetabular side local or
general overcoverage is trimmed. If possible
the labrum is refi xed for better lubrication and
early clinical and radiological results clearly
favor labrum refi xation over resection. On
the femoral side an osteochondroplasty is
performed resecting all nonspherical parts of
the head and reestablishing a normal offset
between head and neck. Experience has
shown that the results are better with early
surgical intervention. While complex morphological
abnormalities are best treated with
surgical dislocation, more isolated pathologies
are more and more treated arthroscopically.
Arthroscopy however needs advanced
experience to avoid collateral damage; for
a combined acetabular and femoral correction
the procedure takes longer than open
surgery.
HIP ARTHROSCOPY
FOR IMPINGEMENT
D. Griffi n
Warwick Medical School
Coventry, Great Britain

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TOTAL HIP REPLACEMENT
FOR THE CONGENITAL
DISLOCATED HIP
K. Soballe
Department of Orthopaeadics, Aarhus
University Hospital. Denmark
We have performed 18 total hip replacements
due to congenitally dislocated hips using the
Paavoleinen technique with shortening of the
proximal femur and placement o the acetabulat
component in the original acetabulum..
The patients were 9 women and 6 men with
a mean age of 38(16-73). All operations were
performed by the same surgeon (KS).
The patients were all classifi ed as C or D
after the Eftekahrs classifi cation. The follow
up period was from 1 to 9 years.
We had no incident of aseptic loosening and
no infections after primary operation was
encountered.
Three patients underwent reoperation due to
wear of the polyethylene liner There were two
reoperations, one due to early displacement
of the cup and one was open reducted due to
dislocation Two patients experienced dislocation
and were reduced close .Only one patient
experienced temporary peroneal nerve palsy
with complete recurrence after 1 week .
Trendelenburg sign was positive in all patients
preoperatively and only in one postoperatively.
Harris Hip Score regarding pain
on an accumulated basis improved from 81
preoperatively to 28 postoperatively. Likewise
the score for walking ability improved from
63 to 29. .
These intermediate results indicate that the
Paavoleinen operation for the congenital
dislocated hip provides the patient with a
stable and functional hip with a limited rate of
complications. The number of disloations is
high but comparable with similar publications
on CDH and can be explained by the altered
biomechanicanical situation and the use of
small 22 mm heads. The problem with wear
of the polyethylene liner in younger patients
is still an unsolved issue but hard bearings
might be a solution if available in small sizes
(40-44 mm cup).
ARTHROPLASTIES IN
DYSPLASTIC HIPS
T. Paavilainen
Hospital ORTON, Helsinki, Finland
Introduction. Cementless method created
new possibilities for replacement surgery of
dysplastic hips. Osteotomies of the femur
and the protrusion socket technique became
feasible. In our hospital the operative methods
were developed in 1980’s, already, when
the Lord´s madreporic components were
adopted. Since then the threaded cups were
replaced with the press fi t ones, and more
appropriate stems have been designed and
manufactured by Biomet Inc.
Operative methods. The acetabular component
is seated at anatomic level or even
lower, if the a-p-diameter at that level is too
small for the cup. The protrusion socket
technique is used in cases with thin pelvic
wall to achieve reliable fi xation of the cup to
the host bone.
The level of resection of the femur is estimated
according to the need of lengthening, and
the type and size of the stem is chosen according
to the shape of the femur at the level
of resection. In cases with high dislocation
we have used two techniques. Most favoured
became the method of proximal shortening
of the femur combined with distal advance-

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ment of the greater trochanter with intact
attachment of the gluteus medius muscle. A
subtrochanteric shortening osteotomy fi xed
with prosthetic stem was the other method.
During the “Lord-period” exact rasping of
the proximal femur and diaphysis distal to
osteotomy and locking the proper rotation by
step method was tedious and time consuming.
Functional results, ROM and abduction
strength were some better with the trochanter
transfer method, although the radiographic
result looks more anatomic and nicer after
the subtrochanteric shortening technique.
Lengthening of the leg was also easier with
the fi rst method. To day we use the latter
technique combined with angular and rotation
correction in cases after low seated unilateral
Schanz osteotomy. With the modern modular
stems with fl uted distal part the procedure is
much easier and faster.
Patient material. The methods are applied
for all grades of DDH, arthrogryphosis,
diastrophic dysplasia, congenital coxa vara
and all kinds of dysplastic hips with osteoarthrosis.
Results. Our experiences and results have
been published in many articles (J Bone Joint
Surg Br. 1990; 72:205-11, Clin Orthop Relat
Res. 1993; 297:71-81, Acta Ortop Scand.
1997; 68:77-84, J Bone Joint Surg Am.
2003; 85:441-7, J Bone Joint Surg Am. 2006;
88:80-91). In the last article Antti Eskelinen
et al. reports results of 68 consecutive hip
replacements performed in DDH-patients
with high dislocation. They were operated
on between 1989-94. Follow-up time was
12,3 y. Harris hip score increased from 54 to
84 points. Trendelenburg sign was negative
in 92% of the cases. With revision because
of aseptic loosening as the end point the ten
year survival rate for press-fi t porous coated
acetabular component was 94,9%(95% confi
dence interval, 89,3% -100%), but all the 9
threaded cups loosened and all but one had
been revised already. There were 6 revisions
of the press-fi t cups because of liner wear and
osteolysis, and 7 patients were scheduled for
liner revision because of wear (1-5mm). The
rate of survival for the DDH stem (proximally
porous coated, Biomet Inc.), with revision because
of aseptic loosening as the end point,
was 98,4% (95% confi dence interval , 96,8%
-100%)at ten years. One malpositioned stem
perforated the posteromedial cortex of the
femur. Two early dislocations occurred because
of excessive anteversion of the stem.
There were four transient nerve palsies, two
peroneal, one femoral and one superior gluteal.
In the case of the other peroneal nerve
palsy, a big postoperative haematoma was
evacuated on the fi rst postoperative day, and
lengthening of the leg was reduced from 5 to
4 cm with successful recovery.
Conclusions. Replacement surgery of different
types of hip dysplasia with osteoarthrosis
is feasible with the presented techniques. In
cases of high congenital dislocation we prefer,
based on our experience, the technique
of proximal shortening of the femur with distal
advancement of the greater trochanter. If
lengthening of the leg is desired more than
3 cm, neurological status is controlled today
with perioperative ENMG. The technique of
segmental shortening with angle correction,
we use only in cases after low seated unilateral
Schanz osteotomy. Nowadays hard on
hard articulations are our fi rst choice to avoid
wear and osteolysis.
PREVENTION AND
TREATMENT OF RECURRENT
DISLOCATION IN THA
R. Geesink
University Hospital Maastricht, Netherlands

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EVALUATION OF THE
PAINFUL THA
D. A. Dennis, M.D.
Adjunct Professor, Dept. of Biomedical
Engineering, University of Tennessee
Assistant Clinical Professor, University
of Colorado Health Sciences Center
Clinical Director, Rocky Mountain Musculoskeletal
Research Laboratory
Denver, Colorado, USA
I. CAUSES OF PAIN AFTER TOTAL HIP
ARTHROPLASTY
A. Articular
1. Prosthetic Loosening
2. Flexural Rigidity Mismatch
a) Femur Vs. Femoral Component Stiffness
3. Infection
4. Instability
5. Component Failure
6. Soft Tissue Impingement
7. Osteolysis
a) Synovitis/ Microfracture
B. Periarticular
1. Trochanteric Bursitis
2. Trochanteric Nonunion
3. Fracture
a) Stress Fracture (Pubic Rami/ Greater
Tuberosity)
b) Avulsion (ASIS/ Ischial Tuberosity)
c) Periprosthetic
4. Iliopsoas Bursitis/ Tendinitis
5. Soft Tissue Contracture
6. Heterotopic Ossifi cation (During Maturation)
7. Piriformis Syndrome
C. Extra-Articular
1. Lumbar Spine Disease
2. Vascular Disease
a) Aortoiliac Stenosis
b) Postoperative Aneurysm/ Pseudoaneurysm
c) Iliofemoral Venous Thrombosis
3. Inguinal/ Femoral Hernia
4. Postoperative Neural Injury
a) Femoral/ Obturator/ Sciatic
5. Psychogenic Factors
II. EVALUATION
A. History
1. Pain Location/ Radiation ??
a) Groin/ Buttock: Acetabular Component
b) Anterior Thigh: Femoral Component
c) Lateral: Greater Trochanteric Bursitis/
Nonunion
d) Buttock/ Posterior Thigh & Calf: Lumbosacral
Spine
2. Pain Onset
a) Initial Painfree Interval Then Late
Pain
• Think Component Loosening/ Failure
or Sepsis
b) Failure To Achieve Any Pain Relief
• Think Periarticular/ Extra-Articular
Source
3. Typical Infection History
a) Night & Rest Pain
b) Fever & Chills
c) Recent Procedures (Dental/ GI/ GU)
4. Typical Aseptic Loosening History
a) ↑ Pain With Activity (Weight-Bearing)
b) ↓ Pain With Rest
B. Physical Exam
1. Abnormal Gait/ + Trendelenberg Test:
Think Articular Source
2. Neurologic Exam
3. FABER TEST (Sacroiliac Disease)
4. Straight Leg Test (L/S Spine Disease)
5. Ober Test (Iliotibial Band Tightness)
6. Range of Motion
7. Extension of Flexed/ Abducted/ Externally
Rotated Hip
a) Iliopsoas Irritation
• Neutral Or Retroverted Cup
• Anterior Cup Edge Exposed
• Trousdale, et al, J Arthroplasty, 1995

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8. Vascular Exam
9. Psychological Analysis
C. Laboratory Analysis
1. GOAL: Differentiate Septic From Aseptic
Cause
2. Hematology
a) CBC With Differential
• Little Value If Used Alone
• Left Shift Suggestive of Sepsis
• Use In Combination With ESR/ CRP
b) Erythrocyte Sedimentation Rate
(ESR)
• Normally Increased For 3-6 Months
Postoperatively
• Infection Sensitivity: 73-100%
• Infection Specifi city: 69-94%
• Diagnostic Accuracy: 73-88%
c) C-Reactive Protein (CRP)
• Normally Returns To Normal By 3
Weeks Postoperatively
• Sensitivity/ Specifi city – Similar To
ESR
d) ESR + CRP Enhances Accuracy
• 100% Sensitivity/ Specificity (K.
Garvin, AAOS, 1996)
3. Hip Aspiration – Questionable Reliability
a) Sensitivity: 40-91%
b) Specifi city: 60-100%
c) False Positive Rates: 16-30%
D. Radiographic Evaluation
1. Plain Radiographs: Loosening Criteria
a) Component Migration
b) Progressive/ Complete Radiolucent
Lines > 2 mm
c) Cement Mantle Fracture
d) Divergent/ Complete Radiosclerotic
Lines With Distal Femoral Pedestal
(Cementless Femoral Component)
2. SERIAL Radiographic Evaluation Valuable
Study Acetabulum Femur
Sensitivity Specifi city Accuracy Sensitivity Specifi city Accuracy
O’Neill & Harris, JBJS 1984 37% 63% 54% 89% 92% 91%
Lyons et al, CORR 1985 63% 89% 69% 76% 100% 84%
Hendrix et al, Radiology 1983 43% 100% 60% 79% 100% 85%
3. Hip Arthrography
a) Valuable In Cemented THA
b) Accuracy < 65% In Cementless THA
• Barrack, et al, Skeletal Radiology,
1994
c) Accuracy Enhanced By:
• High Injection Pressure
• Post-Ambulation Films
• Digital Subtraction Technique
d) Literature Review:
Acetabulum
Sensitivity 38-95%
Specifi city 68-100%
Accuracy 60-90%
Femur
Sensitivity 38-96%
Specifi city 50-100%
Accuracy 83-93%
e) Nuclear Arthrography
• Best For Femoral Component
• Sensitivity: 64-93%/ Specifi city: 75-
100%
4. Nuclear Medicine Scans
a) Technitium – 99m – HDP (99mTc)
• High Sensitivity/ Low Specifi city
• Prolonged ↑ Uptake Normal After
THA (Cemented:6-12 Months/
Cementless: 2 Years)
b) Gallium Citrate
• Localizes In Areas of WBC Accumulation
& Infl ammation
• Low Specifi city If Used Alone
• Best If Combined With 99mTc (60-
80% Accuracy)
c) WBC Indium – 111
• Widely Variable Results
• Sensitivity: 50-100%/ Specificity:
23-100%

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• Accuracy Increased If Combined With
Other Isotope Scans
• Palestro, et al, J Nuclear Med, 1990
==> IIIIn + Sulfur Colloid Bone Marrow
==> 100% Sensitivity/ 97% Specifi city
==> 98% Accuracy
d) Greatest Value Of Nuclear Scans Is A
NEGATIVE Scan !!!
5. Dynamic CT Scan
a) Limited Cuts (Distal Collar/ Distal
Condyles)
b) Anteversion Measured
• Maximum Internal Rotation
• Maximum External Rotation
c) Angular Difference > 2o Highly Suggestive
Of Loosening
d) Berger, et al, CORR 1996
BIBLIOGRAPHY
1. Aalto K, Osterman K, Peltola H, Rasanen
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2. Barrack RL, Tanzer M, Kattapuram SV,
Harris WH: The value of contrast arthrography
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3. Barrack RL, Harris WH: The value of
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6. Carangelo RJ, Scheller AD: Evaluation of
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7. Carlsson AS: Erythrocyte sedimentation
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8. Cuckler JM, Star AM, Alivi A, et al.: Diagnosis
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11. Evans BG, Cuckler JM: Evaluation of the
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14. Garvin KL: Presented at the annual meeting
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15. Gristina AG, Kolkin J: Current concepts
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16. Harris WH, Barrack RL: Developments in
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18. Hendrix RW, Wixson RL, Raina NA, et al.:
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19. Hodgkinson JP, Shelley P, Wroblewski
BM: The correlation between the roentgenographic
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Clin Orthop, 228:105, 1988.

Notas / Notes
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20. Hoppenfeld S: Physical examination of
the spine and extremities. Appleton Century
Crofts, New York, 1976.
21. Johanson NA, Pellicci PM, Tsairis P, et
al.: Nerve injury in total hip arthroplasty.
Clin Orthop, 179:214, 1983.
22. Leriche R, Morel A: The syndrome of
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23. Lieberman JR, Huo MH, Schneider R,
Salvati EA: Evaluation of painful hip arthroplasties:
Are technetium bone scans
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478, 1993.
24. Lyons CW, Berquist TH, Lyons JC, et
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195:239, 1985.
25. Matos MA, Amstutz H, Machleder HI:
Ischemia of the lower extremity after
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61:24-27, 1979.
26. Maus TP, Berquist TH, Bender CE, Rand
JA: Arthrographic study of painful total hip
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27. Maxon HR. Schneider HJ, Hopson CN,
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roentgenographic arthrography
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Clin Orthop, 245:156-159, 1989.
28. Newberg AH, Wetzner SM, Ellis JM:
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JC, Thornhill TS, Bierbaum BE, Turner RH:
Springer-Verlag, New York, NY, 1999.
29. O’Neill DA, Harris WH: Failed total hip
replacement: Assessment by plain radiographs,
arthrograms, and aspiration
of the hip joint. J Bone Joint Surg, 66A:
540-546, 1984.
30. Oswald SG, Van Nostrand D, Savory
CG, Callaghan JJ: Three phase bone
scan and indium labeled white blood cell
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hip prosthesis. J Nucl Med, 30:1321-1331,
1989.
31. Oswald SG, Van Nostrand D, Savory
CG, Anderson JH, Callaghan JJ: The
acetabulum: A prospective study of threephase
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arthroplasty. J Nucl Med, 31:274-280,
1990.
32. Palestro CJ, Kim CK, Swyer AJ, Capozzi
JD, Solomon RW, Goldsmith SJ: Total hip
arthroplasty: Periprosthetic indium-111labeled
leukocyte activity and complementary
technetium-99m-sulfur colloid
imaging in suspected infection. J Necl
Med, 31:1950-1955, 1990.
33. Palestro CJ: Radionuclide imaging after
skeletal interventional procedures. Semin
Nucl Med, 25:3-14, 1995.
34. Sanzen L, Carlsson AS: The diagnostic
value of C-reactive protein in infected total
hip arthroplasties. J Bone Joint Surg,
71B:638-641, 1989.
35. Siliski JM, Scott RD: Obturator nerve
palsy resulting from intrapelvic extrusion
of cement during total hip replacement.
Report of four cases. J Bone Joint Surg,
67A:1225, 1985.
36. Swan JS, Braunstein EM, Wellman HN,
Capello W: Contrast and nuclear arthrography
in loosening of the uncemented
hip prosthesis. Skeletal Radiol, 20:15-19,
1991.
37. Trousdale RT, Cabanela ME, Berry DJ:
Anterior iliopsoas impingement after total
hip arthroplasty. J Arthroplasty 10:546-
549, 1995.
38. Utz JA, Lull RJ, Galvin EG: Asymptomatic
total hip prosthesis: Natural history determined
using Tc-99m MDP bone scans.
Radiolody, 161:509-512, 1986.
39. Van Holsbeeck MT, Eyler WR, Sherman
LS, Lombardi TJ, Mezger E, Verner JJ, et
al.: Detection of infection in loosened hip
prosthesis: Effi cacy of sonography. AJR,
163:381-384, 1994.

Notas / Notes
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40. Walker CW, FitzRandolph RL, Collins DN,
Dalrymple GV: Arthrography of painful hips
following arthroplasty: Digital versus plain
fi lm subtraction. Skeletal Radiol, 20:403-
407, 1991.
41. Weiss PE, Mall JC, Hoffer PB, et al.:
99mTc-methylene diphosphonate bone
imaging in the evaluation of total hip prosthesis.
Radiology, 133:727-729, 1979.
42. Wellman HN, Schausecker DS, Capello
WN: Evaluation of metallic osseous implants
with nuclear medicine. Semin Mucl
Med, 18:126-136, 1988.
43. White RE Jr: Evaluation of the painful
total hip arthroplasty. In The Adult Hip,
Eds., Callaghan JJ, Rosenberg AG, Rubash
HE, Lippincott-Rave, Philadelphia,
pp.1377-1385, 1998
44. Wukich DK, Abrue SH, Callaghan JJ,
Van Nostrand D, Savory CG, Eggli DF, et
al.: Diagnosis of infection by preoperative
scintigraphy with indium labeled while
blood cells. J Bone Joint Surg, 69A:1353-
1360, 1987.
DIAGNOSIS OF THE PAINFUL
CEMENTLESS HIP
R. Geesink
University Hospital Maastricht, Netherlands
LEG LENGHT DISCREPANCY
FOLLOWING THR
D. Dalury
John Hopkins Hospital, Baltimore, USA
Leg length inequality is a common complication
following THR. There is an important
and substantial difference between true and
apparent leg length inequality. Preoperative
planning, including patient education and
templating can help prevent the problem.
Appropriate implant systems, including full
sizing options and offset capabilities can help
the surgeon avoid LLD. Pre-op, intra-op and
post-op techniques to prevent and manage
LLD are discussed.

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17.15 - 19.45 h
CADERA / HIP
Cadera de revisión
Hip revision
Moderador / Moderator: Douglas A. Dennis
CEMENT-IN-CEMENT
REVISION - DECREASING
THE MORBIDITY OF
REVISION SURGERY
J. Timperley
Princess Elisabeth Orthopaedic
Hospital, Exeter, Great Britain
VÁSTAGO DE FIJACIÓN
DISTAL DIAFISARIA EN
CIRUGÍA DE REVISIÓN
A. Coscujuela
Hospital Universitari de Bellvitge,
Barcelona, España
La revisión de un vástago femoral afl ojado
con défi cits óseos de diversa entidad representa
un importante reto para el cirujano. A
causa de los malos resultados obtenidos en
la cirugía de revisión con cemento, se desarrollaron
técnicas de revisión no cementadas.
A fi nales de los 80, Wagner pone a punto su
vástago de revisión, de diseño puntiagudo,
en varias tallas de longitud y grosor, basado
en la fi jación de la prótesis en hueso diafi sario
sano. Utiliza el mismo principio de los clavos
endomedulares, con estabilidad mecánica
inmediata gracias a diversas estriaciones
longitudinales. Es original el abordaje femoral
extendido para facilitar la extracción del
cemento y resección de los granulomas y
membranas de afl ojamiento. Los prometedores
resultados obtenidos hizo que su uso se
generalizara, especialmente en Europa.
En nuestra Servicio lo empezamos a utilizar
a mediados de 1993. Desde entonces hemos
implantado cerca de 200 vástagos femorales
de revisión de fi jación distal tipo Wagner.
Objetivos: Para este curso hemos revisado
expresamente 122 caderas implantadas
entre 1993 y fi nales de 2001, con un seguimiento
mínimo de 5 años (media 7.8 a.) y
conforman la base de esta comunicación.
La fi nalidad de este estudio es mostrar las
posibilidades y problemas en la práctica clínica
con este tipo de implantes, con especial
interés en la supervivencia de los mismos, el
comportamiento mecánico del implante y la
restauración de los defectos óseos. La evaluación
funcional se realizó de acuerdo con
la escala de Merle d´Aubigne. Los defectos
femorales fueron clasifi cados según Paprosky
y los procesos de regeneración ósea del
fémur proximal según Kolstad.
Resultados: Se han excluido 28 pacientes
en la evaluación fi nal: 7 por fallecimiento, 11
pérdidas de seguimiento y 12 retiradas del
implante por diversas razones. La principal
complicación postoperatoria fue la luxación
en 16 casos (13.1%). Se han verifi cado 26
casos (21.3%), de hundimiento secundario
del vástago superior a 5 mm., durante los

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primeros doce meses. La puntuación promedio
de Merle d´Aubigne mejoró desde 7.9
en el postoperatorio hasta 14.9 en la última
revisión. Las últimas radiografi as demostraron
buena regeneración ósea del tercio
proximal femoral en el 52% de los pacientes.
La valoración subjetiva de los pacientes era
satisfactoria en el 71%. La supervivencia
acumulada de los implantes al fi nal del seguimiento
fue del 90%.
Conclusiones: Los vástagos de revisión
de fi jación distal diafi saria proporcionan un
razonable porcentaje de resultados satisfactorios,
tanto clínicos como radiográfi cos,
en la cirugía de revisión de afl ojamientos de
vástagos protésicos femorales con pérdida
ósea de diversa magnitud del tercio proximal
femoral, y perdurando con el paso del tiempo.
También han demostrado su utilidad ante
fracturas periprotésicas y cirugía de revisión
de artroplastias sépticas. En el seguimiento
se ha apreciado una regeneración completa
de la zona proximal, sin utilizar injertos,
en más de la mitad de los casos. Los dos
inconvenientes de este implante que son la
luxación y el hundimiento, se han relacionado
con errores de planifi cación, técnica defi ciente,
apoyo precoz, indicación incorrecta y un
diseño insufi ciente para los requerimientos
biomecánicos.
El perfeccionamiento de estos aspectos o la
alternativa de utilizar otros modelos protésicos
probablemente mejore los resultados en
estas situaciones.
IMPACTATION GRAFT
TECHNIQUE IN THE FEMUR
J. Timperley
Princess Elisabeth Orthopaedic
Hospital, Exeter, Great Britain
WHEN FULLY POROUS
COATED STEMS DO
NOT WORK
W. Paprosky
Rush Arthritis & Orthopaedic Institute
St. Luke’s Medical Center
Chicago, Illinois, USA
REVISION OF THE FEMORAL
COMPONENT USING
EXTENDED TROCHANTERIC
OSTEOTOMY
K. Soballe
Aarhus Universitetshospital, Denmark
LONG-TERM RESULTS HA
COATING IN REVISION THA
R. Geesink
University Hospital Maastricht, Netherlands

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VASTAGO ENCERROJADO IRH
A. Navarro - Ll. Carrera
Hospital Universitario de Traumatologia
Vall d’Hebrón, Barcelona, España
Los defectos femorales proximales severos
representan un problema importante en la
cirugía de revisión del vástago femoral. (7,
12).
La incidencia y severidad de la pérdida de
hueso en la metáfi sis proximal asociada al
afl ojamiento aséptico en las artroplastias
totales de cadera continua incrementándose.
El reto para los cirujanos que realizan estas
revisiones es determinar cual es el mejor método
para fi jar el implante a un fémur con un
gran defecto óseo proximal y que proporcione
estabilidad tanto para la carga como para
la movilidad de la articulación. Igualmente,
la técnica debe ser duradera y permitir la
restauración del défi cit óseo inicial.
Las revisiones con vástagos femorales cementados
presentan resultados impredecibles,
y a medio plazo son poco satisfactorios.
(8,10,19,28).
Gie y Ling (11) proponen la utilización de
aloinjerto impactado para restaurar el defecto
óseo proximal y la cementación de un
vástago liso. Los resultados a medio plazo
tampoco son satisfactorios. (22,25,27).
Otras técnicas utilizadas son los vástagos
largos de anclaje distal y superfi cie porosa
más o menos extensa. Resultados clínicos
pobres.(9,17,20,23,29).
Vástagos cónicos de anclaje distal, (Wagner),
el hundimiento y la luxabilidad del implante
limitan su utilización. (13,14,15,21,26)
Los vástagos modulares de anclaje metafi sario
(S-ROM) favorecen la restauración ósea
metafi saria proximal y presentan resultados
esperanzadores a medio plazo.(4)
Aloinjertos masivos combinados con vástagos
cementados. (12,16,24).
Vástagos con bloqueo distal para conseguir
estabilidad inicial. (32)
En nuestro centro hemos desarrollado un
implante cilíndrico con encerrojado distal,
recubierto de hidroxiapatita. El vástago de
revisión IRH (Interlocking Revision Hip). En
este artículo presentamos los resultados
obtenidos en los 60 primeros casos en los
que se utilizó esta ténica de revisión con un
seguimento medio de 22 meses y mínimo
de 12 meses.
Material y método
Desde Noviembre de 1998 hasta Enero del
2004 se ha utilizado en 80 revisiones de
vástago femoral. Presentamos los resultados
de los 60 primeros vástagos IRH, que correspondían
a 54 pacientes, intervenidos desde
Noviembre de 1998 hasta Enero del 2002.
Las edades en el momento de la revisión
oscilaban de 58 a 81 años, con una media
de edad de 71años. Distribución por sexo, 20
hombres y 34 mujeres. La causa de revisión
era por afl ojamiento aséptico en 58 caderas,
1 caso de fractura patológica y una fractura
periprotésica. Las revisiones se realizaron
por fracaso de prótesis cementadas en 50
casos y no cementadas en 10 casos. En 56
casos era la primera revisión, en 3 casos
la segunda y en un caso el tercer recambio
de vástago. En la mayoría de ocasiones se
recambió el acetábulo excepto en 4 casos.
La valoración preoperatorio de los defectos
femorales se realizó utilizando la clasifi cación
de la AAOS. En 10 casos correspondía al
tipo I, en 19 al tipo II, en 30 al tipo III y en
uno al tipo IV.
Todas las revisiones se realizaron con el
vástago IRH. El vástago IRH (Interlocking
Revision Hip) es una aleación de titanio
recubierta con doble cobertura de alúmina e
hidroxiapatita. Diseño cilíndrico con surcos
longitudinales que aumentan en profundidad
a medida que nos acercamos a la punta
del vástago, por lo que su comportamiento
biomecánico es cónico provocando un gradiente
elástico progresivo. El diseño cilíndrico
permite aumentar las zonas de contacto
óseo. Presenta una ángulación de 135º y
por lo tanto un offset sufi ciente para dismi-

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nuir el riesgo de luxación. El diseño de este
vástago se basa en la estabilización distal
diafi saria inicial, favorecida por la posibilidad
de bloqueo distal con uno o dos pernos
dependiendo de la longitud del vástago.
Esta estabilización primaria favorece la osteointegración
secundaria metafi so-diafi saria
gracias a la cobertura de hidroxiapatita. El encerrojado
distal permite el ajuste longitudinal
y la rotación del implante, permitiendo tantas
pruebas de estabilidad articular como sean
necesarias antes del bloqueo defi nitivo. El
bloqueo proximal y la aleta dorsal permiten el
cierre de la osteotomía y con ello la correcta
reinserción y tensión de los pelvitrocantéreos.
Los vástagos tienen longitudes desde 210
a 310 mm y diámetros desde 12 a 22 mm
con incrementos de 2 en 2 mm. Todos los
vástagos femorales han sido insertados con
cabezas de 28 mm, aunque también puede
colocarse con una cabeza de 32 mm si el
caso lo requiere.
Todos los casos han sido intervenidos en
decúbito lateral, abordaje posterior, osteotomía
transtrocantérica ampliada de más de
12 cm (todos los casos excepto 1, fractura
patológica). Después de extraer el implante,
el cemento y las membranas se realiza una
revaloración del defecto óseo preoperatorio,
que suele ser siempre mayor al planifi cado.
Iniciamos el fresado progresivo de la diáfi sis
femoral 1 o 2 mm más del tamaño elegido.
Se valora la adaptación y estabilidad del
implante con un adaptador de prueba. A
continuación se introduce el vástago defi nitivo,
se reduce la articulación y se ajusta en
rotación y en longitud. Cuando la adaptación
del implante es la deseada procedemos al
bloqueo distal, con uno o dos pernos dependiendo
de la longitud del vástago (a partir de
270 mm). Por último, procedemos al cierre
de la osteotomía con el tornillo de bloqueo
proximal y/o cerclajes metálicos a través de la
aleta dorsal. Colocamos injerto homólogo, si
es necesario y cerramos el campo operatorio
dejando dos redones profundos de aspiración
a baja presión.
Postoperatorio: La conducta postoperatoria
ha variado a medida que hemos ganado
experiencia sobre el comportamiento del
implante. El tiempo de encamamiento ha pasado
de 12-15 días a 2-3 días dependiendo
de las características del paciente. A las 48
horas se retiran los drenajes y se inicia sedestación
según tolerancia. Si la sedestación
es bien tolerada se inicia la deambulación
con ayuda de bastones y carga parcial progresiva.
La media de estancia hospitalaria es
de 10 días. El control clínico y radiológico se
realiza de forma periódica a las 6 semanas,
3 meses, 6 meses y al año. Posteriormente
se controlan cada año. A los 3 meses todos
los pacientes son autorizados a cargar todo
el peso en la extremidad afecta con o sin
ayuda de bastones.
Todos los pacientes han sido evaluados
clínicamente con un seguimiento mínimo de
12 meses excepto un paciente que falleció
a consecuencia de un TEP masivo en el
postoperatorio inmediato. Seguimiento medio
22 meses. Se utilizó la escala de Harris para
la valoración funcional del paciente. Valorándose
en los controles la presencia o no de
dolor en el muslo.
El estudio radiológico seriado, proyección
anteroposterior y lateral de cadera incluyendo
el fémur distal en 59 vástagos útiles
para el seguimiento. Se compararon las
radiografi as del postoperatorio inmediato
con las tomadas al año de evolución. Dado
que la confi rmación histológica no era posible
se determinó la estabilidad del implante
siguiendo los criterios de Engh. (9). para la
osteointegración. La estabilidad se clasifi có
en integración, integración fi brosa estable y
en inestable. La valoración del hundimiento
vertical se realizó utilizando los criterios de
Callaghan et al. Hundimientos superiores a 5
mm fueron considerados como signifi cativos.
También se valoró la presencia de líneas de
radiolucéncia y su progresión.
Se realizó la valoración global de todos los
estudios radiológicos de cada paciente.
Resultados
La media de la puntuación preoperatorio se-

Notas / Notes
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gún la escala de Harris era de 42.5 puntos en
los 60 vástagos. Un paciente había fallecido
en el postoperatorio inmediato a causa de un
TEP. En el momento de la valoración, media
de seguimiento 22 meses, la puntuación
media fue de 81.6 puntos. En el momento
de la revisión los resultados obtenidos fueron
califi cados como excelentes en 50 de los
59 casos (85%), buenos en 6 casos (10%)
y malos en 1 caso (1,5%). En ningún caso
existía dolor en cara anterior del muslo.
El mal resultado fue un paciente en el que
por error no se practicó correctamente el encerrojado
distal y progresivamente determinó
un hundimiento del vástago. Se solventó
colocando un implante primario modular
recubierto de hidroxiapatita.
En los 59 pacientes útiles para el seguimiento
se valoró la radiología seriada. Utilizando
los criterios de Engh para la valoración de
la estabilidad del implante. 58 pacientes
mostraban integración global del implante
en zona diafi saria (98%). Se valoró el hundimiento
siguiendo los criterios de Callaghan,
un implante presentaba hundimiento superior
a 5 mm, lo que condicionó el recambio del
mismo. En ningún caso existían zonas de
radiolucencia lineal ni progresiva.
Todas las osteotomias consolidaron, incluso
aquellas en las que no se aportó injerto
óseo.
Ningún paciente presentó dolor en la cara
anterior del muslo.
Complicaciones: Dos rupturas del implante,
1 fractura periprotésica peroperatoria se la
cortical femoral anterior que fue tratada de
forma consevadora y que no infl uyó en la
evolución clínico-radiológica del implante.
Dos migraciones del tornillo proximal que
obligó a su retirada en un caso. Un fallo del
encerrojado distal que condicionó el posterior
hundimiento y fracaso del implante. Una
luxación postoperatoria a los 3 meses tras
un traumatismo de baja energía.
Discusión
La utilización de vástagos cementados en
la cirugía de revisión presenta peores re-
sultados que en la cirugía primaria cuando
no incluye restauración biológica del défi cit
óseo. Los porcentajes de rerevisión oscilan
desde el 9 % (10, 28) al 49 % (8, 19).
La restauración del défi cit óseo es necesaria
para mejorar los resultados. Existen distintas
técnicas quirúrgicas.
. Técnica de Exeter. (11). La utilización
de aloinjerto troceado permite la reconstrucción
ósea cuando el fémur proximal
es sufucientemente estable en defectos
cavitarios puros o combinados que pueden
convertirse en continentes. Presenta
un elevado índice de complicaciones,
hundimientos y fracturas periprotésicas,
por lo que sus indicaciones son muy restringidas.
(22, 25, 27).
. Los vástagos largos de anclaje distal y
superfi cie porosa presentan resultados
difíciles de valorar debido a la gran variabilidad
en su diseño y en la extensión de
la superfi cie porosa. El dolor en la cara anterior
del muslo y el stress-shielding, que
disminuye la capacidad de restauración
ósea proximal, hacen que no recomendemos
su utilización de forma sistemática.
(17, 23, 29). (9, 20).
. Vástagos recubiertos de hidroxiapatita.
Las características biológicas de la hidroxiapatita
favorecen la formación ósea,
reconstrucción del defecto óseo y osteointegración
del implante. (2, 5, 6).
. Los vástagos modulares de anclaje metafi
sario (S-ROM) presentan resultados
esperanzadores a corto plazo con un 6 %
de fracasos a los 6 años. La fi jación metafi
saria favorece la hipertrofi a endostal y
cortical reconstruyéndose el defecto óseo
femoral proximal. No tenemos experiencia
en su utilización.(4)
. Aloinjertos masivos combinados con vástagos
no cementados. Head, McLaughlin
y Gross presentan resultados aceptables.
Es una técnica a valorar en casos
de grandes defectos óseos que exijan
la utilización de aloinjertos estructurales
masivos. (12, 16, 24).
. En 1987, Wagner presentó una técnica

Notas / Notes
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de revisión con un vástago cónico largo
de anclaje diafi sario distal con excelente
regeneración ósea proximal espontánea.
El anclaje del vástago se consigue por
implantación en la diáfi sis femoral tras
el fresado cónico de la misma. Wagner
recomienda su utilización en presencia de
defectos femorales proximales utilizando
la via transfemoral o trocanterectomía ampliada.
Basándose en la fi jación diafi saria
distal del vástago cónico, se busca una
fi jación primaria perfecta que favorezca
la ulterior osteointegración por aposición
ósea entre los surcos protésicos. (31).
Las publicaciones de Hartwing, Kolstad,
Grüning y Michelinakis están de acuerdo
en tres hechos importantes:
a). Reconstrucción biológica del fémur
proximal en la mayoría de los casos,
incluso sin aporte de injerto óseo.
b) Hundimiento del vástago
c). Luxabilidad del implante.
d). Planifi cación preoperatoria exigente.
(13,15,21,26).
Böhm y Bischel tras revisar 129 vástagos
con un seguimiento medio de 4.8 años
mostraban un hundimiento medio de 5.9
mm y 7 casos de luxación. (3).
Gutierrez y Garcia Cimbrelo en una reciente
revisión de 55 vástagos con un
seguimiento medio de 6 años presenta
hundimientos mayores a 3 mm en 11
caderas y 7 luxaciones. (14).
En una reciente revisión realizada en
nuestro centro, 88 casos con un seguimiento
medio de 6.5 años hemos podido
observar:
. Hundimiento en el 45 % de los casos con
una media de 13.7 mm. . Fracturas femorales
periprotésicas, per y postoperatorias
en el 16 % de los casos.
. Luxación en el 6.8 % de los casos.
. Regeneración ósea proximal en el 65 %
de los casos.
. Contacto metal-hueso 27.57 mm. Mucho
menor de lo recomendado, de 7-10
cm.(31)
Creemos que el vástago de Wagner es una
buena opción para el tratamiento de los
afl ojamientos protésicos con importantes defectos
óseos femorales proximales, aunque
presenta un índice de hundimiento importante
y una elevada tasa de luxabilidad que exige
un encamamiento postoperatorio largo.
La planifi cación preoperatoria es compleja
para determinar la longitud y el grosor del
implante. Presenta poco off-set lo que facilita
la luxación. Es difi cil ajustar la longitud y la
anteversión, ya que una vez impactada es
imposible la vuelta atrás.
Conclusiones
Creemos que el vástago IRH puede ser una
buena alternativa para el tratamiento de los
aflojamientos asépticos de los vástagos
femorales con grandes pérdidas de hueso
metafi sario.
Al inicio utilizabamos el vástago IRH solo en
casos de grandes defectos óseos femorales
o fracturas periprotésicas. Sin embargo, los
excelentes resultados obtenidos hasta la
fecha han hecho que se halla convertido en
la técnica de elección para la mayoría de los
recambios de vástago femoral en nuestro
centro.
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hips followed for 1.5-5 years. Acta Orthop
Scand. 67:6, 541-4. 1996.
22. Leoplold. S, Rosenberg. A: Current status
of impactation allografting for revision of
a femoral component. J Bone and Joint
Surg., 81-A:1337-45. 1999.
23. Malchau. H, Wang. YX, Kärrholm. J, Herberts
P: Scandinavian multicenter porous
coated anatomic total hip arthroplasty
study. Clinical and radiografi c results with
7 to 10 year follow up evaluation. J Arthroplasty.
12:2, 133-48. 1997.
24. McLaughlin. J, Harris. W: Revision of
femoral component of a total hip arthroplasty
with the calcar-replacement femoral
component. Results after a mean of 10.8
years postoperatively. J Bone and Joint
Surg., 78-A:331-339. 1996.

Notas / Notes
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25. Meding. J, Ritter. M, Keating. M, and Faris.
Ph: Impactation bone grafting before
insertion of a femoral stem with cement in
revision total hip arthroplasty. J Bone and
Joint Surg., 79-A: 1834-1841. 1997.
26. Michelinakis. E, Papapolychronlou. T,
Vafi adis. J: The use of a cementless femoral
component for the managment of
bone loss in revision hip arthroplasty. Bull
Hosp Jt Dis. 55:1, 28-32. 1996.
27. Ornstein. E, Atroshi. I, Franzen. H, Johnsson.
R, Sandquist. P and Sundberg.
M: Early complications after one hundred
and forty-four consecutive hip revisions
with impacted morselized allograft bone
and cement. J Bone and Joint Surg., 84-A:
1323-1328.2002.
28. Raut. VV, Siney. PD, Wroblewski. BM:
Outcome of revision mechanical stem faliure
using the cemented Charnley´s stem.
A study of 339 cases. J Arthroplasty. 11:4,
405-10. 1996.
29. Souminen. S, and Santavirta. S: Revision
total hip arthroplasty in defi cient proximal
femur using a distal load-bearing prosthesis.
Ann Chir Gynaecol. 85:3, 253-62.
1996.
30. Sugimura. T, Tohkura. A: THA revision
with extensively porous coated stems.
32 hips followed 2-6.5 years. Acta Orthop
Scand. 69:1, 11. 1998.
31. Wagner. H: A non allogaft press fi t alternative.
Current Concepts in Joint Replacement.
Orlando. December 1995.
32. Young-Min Kim, Hee Joong Kim, Won
Seok Song, Jeong Joon Yoo. Experiences
with the biocontact revisions tems
with distal interlocking. J Arthroplasty 19
(1):27-33. 2004.
FRACTURAS PERIPROTÉSICAS
C. Mestre
Hospital de l’Esperança IMAS,
Barcelona, España

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Notas / Notes
Jueves, 30 de noviembre
Thursday, 30th November
md
CADERA / HIP
Acetábulo
Acetabulum
RODILLA / KNEE
Unicompartimentales
Prótesis total de rodilla
Unicompartimentals
Total knee arhroplasty
Moderadores / Moderators: Luís Azorin, Xavier Flores
Peter McLardy-Smith, Richard “Dickey” Jones,
Francisco Gomar, Michael Freeman
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08.00 - 12.00 h
CADERA / HIP
Acetábulo
Acetabulum
Moderador / Moderator: Luís Azorin, Xavier Flores
PREOPERATIVE EVALUATION
OF THE BONE LOSS
W. Paprosky
Rush Arthritis & Orthopaedic Institute
St. Luke’s Medical Center
Chicago, Illinois, USA
THE ROLE OF BONEGRAFTING
IN ACETABULAR OSTEOLYSIS
C. H. Rorabeck, MD
Health Sciences Centre, Ontario, Canada
Modularity in total hip arthroplasty has allowed
for the retention of well fi xed components
during revision surgery. In particular,
osteolysis, polyethylene wear, or impingement
are increasingly being treated with an
isolated polyethylene liner exchange, leaving
in place well in-grown acetabular and femoral
components. The purpose of this study was
to examine the clinical and radiographic results
of isolated polyethylene liner exchange
surgery and determine its effectiveness in a
clinical setting.
Twenty-four hips (23 patients) were treated
with isolated polyethylene liner and modular
femoral head exchange for polyethylene
wear and osteolysis or impingement. All
surgeries were performed through the direct
lateral approach. All patients were followed
clinically and radiographically with a mean
follow up of 31 months (range 6 to 100
months). Patients who underwent revision for
recurrent dislocation were excluded. Clinical
results were assessed using the Harris Hip
score and Western Ontario and McMaster
Universities (WOMAC) index. A computer-assisted
method was employed to quantitatively
determine lesional area on radiographs for
those patients who presented with osteolysis.
All accessible osteolytic lesions were bone
grafted at the time of liner exchange.
Progressive acetabular osteolysis was identifi
ed in 18 hips, 15 of which required bone
grafting. Preoperatively, the mean area of
osteolysis from anteroposterior radiographs
was 542.9 mm2 while that determined on
lateral radiographs was 794.7 mm2. All lesions
have either regressed or resolved since
the procedure. Clinically Harris Hip Scores
improved post-operatively by an average of
14.1 points from 69.3 to 84.1, while WOMAC
scores improved by 15.3 points. Two patients
required a subsequent revision. None of the
hips have dislocated since the liner exchange
procedure performed via the direct lateral
approach.
CONCLUSION
Isolated liner exchange with or without bone

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grafting is an effective method in treating
polyethylene wear and associated osteolysis
in selected patients. Dislocation rates may
be reduced with use of the direct lateral
approach and this reduction is reported as
a signifi cant fi nding of this study. Isolated
liner exchange is becoming increasingly
common as a revision procedure following
total hip arthroplasty. A new simple computer-assisted
technique of measuring and
quantifying lesional area on standard AP and
lateral radiographs is described, and provides
a useful tool in the clinical setting.
CONSTRAINED
LINERS IN REVISION THA
W. Paprosky
Rush Arthritis & Orthopaedic Institute
St. Luke’s Medical Center
Chicago, Illinois, USA
USE OF CAGES IN
ACETABULAR REVISION
SURGERY
P. Beaulé
Associate Professor
University of Ottawa, Canada
Revision acetabular reconstructions represent
a great challenge to orthopaedic surgeons,
particularly with severe segmental
and cavitary pelvic defi ciencies. In general,
a porous-coated, noncemented cup with at
least 50% host bone coverage can be used, if
the option of cementless fi xation is chosen.1
Defi ciencies are fi lled with allograft, either
structural or particulate. However, defi ciencies
requiring greater than 50% coverage by
allograft should be supported by a metal back
ring with a cemented cup.1,2 This protects the
graft from mechanical overload during its revascularization
phase. The majority of these
defi ciencies fall into type III and IV defects as
defi ned by the American Association of Orthopaedic
Surgeons classifi cation system.2,3
The most common metal rings have been the
Muller acetabular ring4 and the Burch–Schneider
antiprotrusio cage.5,6 Another design
is the ring hook cages fi rst introduced by Kerboull7
and later adapted to the Muller ring by
Ganz,8 and also available as the Restoration
GAP Cup9 (Stryker–Howmedica–Osteonics,
Allendale, NJ). The techniques to insert
these devices are variable in terms of optimal
position and allograft use. More specifi cally,
little emphasis has been placed in restoring
normal hip anatomy, with the majority of the
surgical technique focusing on placing the
cage on intact host bone.6,9
There is clinical and biomechanical evidence
that joint reaction forces increase with
superior and lateral placement of the hip
center.10-12 In his classic article, Johnston
et al10 demonstrated that inferior and medial
placement of the hip center resulted in a
maximum reduction of the joint reaction force
and the moment-generating requirements of
the muscles. Delp et al12 showed, with a 3dimentional
computer model, that increasing
the hip center by 2 cm in the superior and
lateral direction decreases abductor moment
arms by 28%. However, increasing the hip
center in the superior direction alone, along
with prosthetic neck length compensation,
had little effect on moment arms. Joint reaction
forces similarly increase with superior and
lateral hip center placement of greater than
25 mm, as shown in an experimental model
reported by Doehring et al.13 These authors
demonstrated that with a 25-mm displacement
of the hip center, the joint reaction force

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increased by 29% (~7.5-8.0 Xbody weight); it
increased by up to 37% with a displacement
of 37 mm. This compared with a joint reaction
force of 1.5 to 2.0 X body weight at the normal
hip center. There was no increase in the joint
reaction force with superior hip placement
alone. Vertical placement of the acetabulum
has been shown to have higher polyethylene
wear rates as well.14,15 These factors may
infl uence the rate of mechanical failure in
metallic reinforcement devices. Udomkiat
et al16 reported clinical and radiographic
short-term results of 3 different metallic
reconstruction devices (Burch–Schneider,
Ganz, and Muller) for primarily type II and III
defects. The overall mechanical failure rate,
at an average of 4.6 years, was 17%. The
Burch–Schneider cage had less favorable
biomechanical characteristics than the other
devices—abduction angles of 70.7 +12.6 and
elevated hip centers of 16.6 +12.5 mm. Hip
center lateralization was not documented,
which could show an even more unfavorable
biomechanical environment. The Ganz ring,
with an inferior hook, had abduction angles
of 61.9 +10.5 and elevated hip centers of
12.6 +15.2 mm. No statistical analysis was
documented on these parameters; however,
there was no difference in the mechanical
failure rate between the 3 devices. Their
conclusions were that structural allograft, in
contrast to particulate allograft, should be
used in the superior portion of the acetabulum
to prevent early failure. However, there
was no consideration of the unfavorable
biomechanical environment around the graft
itself, which most likely contributed to early
failure. In general, the surgical technique,
particularly with the Burch–Schneider cage,
focused on stabilizing the implant on host
bone. This would lead, particularly with large
defi ciencies, to superior and lateral hip center
placement, which would explain a higher
mechanical failure rate. In contrast, Kerboull
et al7 reported a 10-year follow-up survivorship
rate of 92.1 +5% for on type III and IV
defi ciencies. The biomechanical parameters
were more favorable, with a device abduc-
tion angle of 38.7 +7.6. This device and the
surgical technique focus on normal hip center
orientation with an inferior crimping hook,
similar to the Restoration GAP cup.
However, the need to use structural allografts
with gages does not provide immediate stability
of the construct and relies on a favorable
integration of the graft to the host bone which
is not 100% predictable. Consequently, the
introduction of new metals such as tantalum
offer immediate stability of the implant and
avoids premature failure of structural allografts18.
References
1. Lewallen DG, Berry DJ: Acetabular revision:
Techniques and results, in Morrey
BF (ed): Joint Replacement Arthroplasty.
Philadelphia, Churchill Livingstone, 2003,
pp 824-843.
2. Paprosky WG, Perona PG, Lawrence JM:
Acetabular defect classifi cation and surgical
reconstruction in revision arthroplasty.
J Arthroplasty 9:33-44, 1994
3. D’Antonio JA, Capello WN, Borden LS,
et al: Classifi cation and management of
acetabular abnormalities in total hip arthroplasty.
Clin Orthop 243:126-137, 1989
4. Muller ME: Acetabular revision, in Salvati
EA (ed): Proceedings of the Open Scientifi
c Meeting of The Hip Society. St Louis,
Mosby, 1981, pp 46-56
5. Rosson J, Schatzker J: The use of reinforcement
rings to reconstruct defi cient
acetabula. J Bone Joint Surg 74B:716-
720, 1992
6. Berry DJ, Muller ME: Revision Arthroplasty
using an anti-protrusio cage for massive
acetabular bone defi ciency. J Bone Joint
Surg 74B: 711-715, 1992
7. Gill TJ, Siebenrock KA, Oberholzer R, et
al: Acetabular reconstruction in develop-

Notas / Notes
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mental dysplasia of the hip: Results of the
acetabular reinforcement ring with hook. J
Arthroplasty 14:131-137, 1999
8. Sledge CB, Chandler HP: Acetabular
revision, in Sledge CB (ed): The Hip.
Philadelphia, Lippincott-Raven, 1998, pp
295-304
9. Johnston RC, Brand RA, Crowninshield
RD: Reconstruction of the Hip. J Bone
Joint Surg 61A:639-652, 1979
10. Yoder SA, Brand RA, Pedersen DR, et al:
Total hip acetabular component position
affects component loosening rates. Clin
Orthop 228: 78-87, 1988
11. Delp SL, Wixson RL, Komattu AV, et al:
How superior placement of the joint center
in hip arthroplasty affects the abductor
muscles. Clin Orthop 328:137-146, 1996
12. Doehring TC, Rubash HE, Shelley FJ,
et al: Effect of superrio and superolateral
relocations of the hip center on hip joint
forces: An experimental and analytical
model. J Arthroplasty 11:693-703, 1996
13. Kennedy JG, Rogers WB, Soffe KE, et al:
Effect of acetabular component orientation
on recurrent dislocation, pelvic osteolysis,
polyethylene wear, and component migration.
J Arthroplasty 13:530-534, 1998
14. Schmalzried T, Guttmann D, Grecula M,
et al: The relationship between the design,
position, and articular wear of acetabular
components inserted without cement in
the development of pelvic osteolysis. J
Bone Joint Surg 76A:677-688, 1994
15. Udomkiat P, Dorr LD, Won Y-Y, et al: Technical
factors for success with metal ring
acetabular reconstruction. J Arthroplasty
16:961-969, 2001
16. Kerboull M, Hamadouche M, Kerboull
L: The Kerboull reinforcement acetabular
reinforcement device in major acetabular
reconstructions. Clin Orthop 378:155-168,
2000
17. Judet R, Judet J, Letournel E: Fractures of
the acetabulum: classifi cation and surgical
approaches for open reduction. J Bone
Joint Surg 46A:1615-1646, 1964.
18. Sporer and Paprosky: The use of a
trabecular metal acetabular component
and trabecular metal augment for severe
acetabular defects. J Arthroplasty. 2006
Sep;21(6 Suppl 2):83-6.
RINGS, THINGS AND CAGES
W. Paprosky
Rush Arthritis & Orthopaedic Institute
St. Luke’s Medical Center
Chicago, Illinois, USA
IMPACTION GRAFT
TECHNIQUE IN THE SOCKET
J. Timperley
Princess Elisabeth Orthopaedic
Hospital, Exeter, Great Britain

Notas / Notes
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EL COTILO DE TANTALIO
EN CIRUGÍA DE CADERA
A. Murcia Mazón,
R. Iglesias Colao, M. A. Suárez Suárez
Hospital de Cabueñes.
Facultad de Medicina. Oviedo, España
Introducción
La artroplastia total de cadera es una de las
intervenciones que mejor coste-beneficio
tiene dentro de los procedimientos ortopédicos.
Además cada vez es más frecuente
la indicación de artroplastias de cadera en
pacientes jóvenes y la cirugía de revisión en
pacientes con pérdidas de masa ósea. Por
ésta razón los implantes empleados deben
ser especialmente adecuados en cuanto a su
diseño, material y estructura material. En el
diseño interviene la morfología y el tamaño;
los materiales deben tener extrema compatibilidad
y poseer las características mecánicas
y biológicas adecuadas; por último la estructura
del implante permitirá la osteoconducción
y preferiblemente una osteoinducción rápida
y segura. Los materiales de uso clínico son
de tres tipos, cerámicas (fosfatos, BCP),
polímeros (TMC-LPLA-DLPLA), y metales,
entre los que tenemos el titanio (Ti), nitinol
poroso (NiTi), y tantalio (Ta).
El tantalio es un material biocompatible, con
excelentes posibilidades de osteointegración
confi rmadas histológicamente, que se empezó
a utilizar en el hospital de Cabueñes
en enero de 2000. Tiene una porosidad del
80%, poros interconectados de 550 _m, con
un módulo de elasticidad de 3 GPa similar
al del hueso subcondral. Su módulo de
elasticidad es de 50-80 MPa, inferior a otros
sistemas porosos.
El tantalio es un elemento metálico puro que
ocupa el número 73 en la tabla periódica. Es
fuerte, dúctil, resistente a la corrosión y altamente
biocompatible, similar en muchos aspectos
al titanio. Tiene buenas propiedades
mecánicas y se emplea en medicina desde
hace más de 50 años en placas de craneoplastia,
derivaciones de marcapasos etc. Se
utiliza como material de implante (1,2,3) en
Ortopedia a partir de 1994, presentando los
primeros resultados del crecimiento óseo en
su interior en animales en 1995 (4).
Los primeros resultados con el Tantalio son
tan prometedores que se piensa que puede
ser para los próximos años lo que fué el
Titanio diez años atrás. La experiencia con
el cotilo de tantalio (Hedrocel), empieza en
nuestro país en 1995 y entre sus resultados
destaca la práctica ausencia de líneas radiotrasparentes
y la excelente tolerancia por
parte del esqueleto receptor al implante.
Dados los excelentes resultados obtenidos
con el cotilo monobloque para cirugía primaria
se ha ampliado su utilización en cirugía de
revisión con el cotilo en dos piezas; una que
se solidariza al hueso receptor con tornillos
y que recibe un inserto de polietileno cementado
con el fi n de evitar micro-movimientos
entre ambos componentes. Además se
dispone de unos aumentos que se adaptan
al cotilo defi nitivo, del mismo radio y distinta
anchura, que permite corregir los defectos
acetabulares existentes.
Material y Métodos
1.- Técnica quirúrgica
En cirugía primaria, identifi cación y referencia
del piramidal, sección de los rotadores externos,
capsulotomía. Luxación de la cabeza
femoral y osteotomía del cuello. En cirugía
de revisión se ha utilizado el mismo abordaje
que para otros procedimientos de reconstrucción,
con sección del tendón conjunto
y si hace falta del psoas iliaco. El fresado
acetabular se ha realizado línea a línea implantando
el cotilo del mismo número que la
última fresa, ya que el implante defi nitivo se
encuentra sobredimensionado. Sólo cuando
el diámetro del cotilo era superior a 58 mm
se fresaba con números impares con el fi n
de realizar un fresado infra-dimensionado

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en 1 mm.
Se ha comprobado de utilidad el comprobar
con el cotilo de prueba el nivel de impacción,
pues de otro modo resulta difícil calcular
la adecuada profundidad del mismo. Dada
la porosidad del implante es necesario la
exposición completa y circunferencial del
acetábulo para que no se adhiera a tejidos
blandos y que éstos se interpongan; situación
que en ocasiones resulta incómoda
cuando se realiza a través de una miniincisión
posterior.
En los casos de cirugía de revisión, en
primer lugar hay que reconstruir el defecto
óseo presente una vez que se hay fresado
y previsto el tamaño adecuado del anillo de
revisión. La fi nalidad es conseguir que el
implante defi nitivo esté en contacto con la
mayor cantidad posible de hueso receptor,
que es donde se podrá realizar una fi jación
primaria suplementada con tornillos, aunque
si hace falta se puede perforar el tantalio con
una broca rígida corriente.
Una vez colocado el aumento que reconstruye
el defecto, queda un espacio hemiesférico
correspondiente al implante acetabular
previamente planifi cado. Conviene colocar
un poco de cemento entre ambas intercaras.
A continuación se cierran los orifi cios no utilizados
del implante acetabular con cera ósea
para poder presurizar el cemento y que no
se interponga entre la superfi cie externa del
cotilo defi nitivo y el hueso receptor.
Si existe un defecto en la pared medial que
aconseja la colocación de un restrictor, se
debe calcular el tamaño adecuado y una vez
colocado en su sitio se debe poner injertos
óseos troceados que se compactan. El cierre
se realiza reconstruyendo con puntos transóseos
la cápsula, rotadores y piramidal.
2.- Cotilo monobloque de tantalio
El cotilo implantado, motivo del estudio es
un cotilo sólido sin orifi cios para tornillos,
ajustado a presión, que reúne tres tipos de
características:
1) por un lado las propiedades inherentes
del tantalio, porosidad del 80% y con intercomunicación
entre los poros, con módulo
de elasticidad muy inferior al titanio y al
cromo-cobalto, y muy parecido al hueso esponjoso;
2) forma elíptica, de forma que el diámetro es
dos milímetros mayor que la fresa; no hay interferencias
en el ápex de la cúpula por lo que
el ajuste es completo; y la forma elíptica evita
fuerzas de extracción en el ápex mientras que
en el resto son de compresión; (9); 3) y en
tercer lugar el inserto de polietileno se moldea
por compresión directa dentro del soporte
metálico de tantalio con lo que se eliminan los
micromovimientos entre el soporte metálico y
el inserto por lo que el desgaste y suelta de
partículas es mucho menor.
3.- Cotilo de revisión de tantalio. Aumentos
El cotilo de revisión consta de dos componentes;
por un lado el anillo metálico de tantalio,
que una vez estabilizado con tornillos a la
hemipelvis, recibe en su interior un inserto
de polietileno que es cementado con el fi n
de evitar los micromovimientos al igual que
se consigue con el monobloque.
En la reconstrucción acetabular en primer
lugar se debe reconstruir cualquier tipo de
defecto óseo con el aumento, con el fi n de
dejar un espacio hemisférico para el cotilo
defi nitivo, teniendo en cuenta que se puede
utilizar una fresa hemisférica para hacerle
el lecho estable al aumento, ya que éste
es una hemiesfera parcial. A continuación
se coloca en posición en anillo defi nitivo de
tantalio, que se solidariza al hueso receptor
con tornillos. Si hace falta se puede perforar
con broca rígida y añadir los tornillos necesarios.
Se tapan los agujeros libres con cera
ósea y se cementa presurizando el inserto
de polietileno.
4.- Estudio clínico
Los pacientes intervenidos han sido 176
siendo 82 artroplastias primarias y el resto,

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92 de cirugía de revisión. Se implantaron 27
aumentos y dos restrictores centrales. Todos
los pacientes fueron intervenidos en decubito
lateral, todos los de revisión y la mayor parte
de las artroplastias primarias por abordaje
posterior y solo en 9 ocasiones por abordaje
transglúteo.
El acetábulo de revisión se ha utilizado en 92
pacientes, y en la mayoría de los casos, 63,
se ha realizado también el recambio del componente
femoral. En las reconstrucciones
acetabulares se ha utilizado 27 aumentos,
lo que signifi ca el 34.6% de los casos de
cirugía de revisión.
Aunque la mayoría de las artroplastias
primarias fueron ambos componentes sin
cementar; 20 fueron híbridas implantando
un vástago Exeter cementado, presurizado
y sellado. Los pares de fricción utilizados
han dependido de la edad del paciente;
cerámica-polietileno si era menor de 65 años
y metal-polietileno si mayor. En el análisis
retrospectivo de los casos, se analiza el
tamaño del implante tanto acetabular como
femoral y longitud del cuello, en los casos
de artroplastias primarias y de revisión. Se
valora el tamaño de la última fresa y diámetro
del cotilo implantado, lo mismo que si hubo
alguna complicación intraoperatoria.
La edad media ha sido de 64.2 años con un
rango entre 44 y 87 años. El 59% de los pacientes
han sido hombres y el 41% mujeres. La
serie personal ha aumentado en 30 pacientes
14 de cirugía primaria y 16 de cirugía de revisión,
con respecto a la presentada en 2005.
El régimen postoperatorio ha sido el mismo
que para cualquier otro tipo de artroplastia.
Las revisiones clínicas y radiográfi cas fueron
a las seis semanas, tres, seis y doce meses;
y a continuación anualmente.
5.- Estudio radiográfi co
Los componentes acetabulares ajustados a
presión tanto en cirugía primaria de cadera
como en cirugía de revisión, se ha convertido
en práctica habitual en una buena parte de
centros dedicados a la cirugía de cadera,
aunque persisten algunas controversias.
Gruen (5) estudian 574 artroplastias primarias
en 542 pacientes y revisan 113 zonas
en 85 caderas (21%) con gaps acetabulares
que se encontraban distribuídos 36 en zona
I, 72 en zona II y 5 en zona III. De estas
radiolucencias 57 zonas fueron de 1 mm
o menos y 56 zonas entre 2 y 5 mm. En la
última revisión radiográfi ca entre 2 y 5 años
de seguimiento, 64 caderas (75%) se había
rellenado el espacio, incluyendo el 100 % de
los gaps mayores de 2 mm.
Igualmente Lewis (6) estudia 165 casos
mediante radiografías seriadas para valorar
la evolución de las radiolucencias periacetabulares
en cada una de las zonas de De
Lee y Charnley, comprobando que el 33%
de los casos presentaban en la primera
radiografía, líneas radiotrasparentes sobre
todo en la zona II y habitualmente eran
menores de 2 mm. En el último control radiográfi
co los 165 cotilos parecían completamente
osteointegrados con una media
de 34 meses. Las líneas radiotrasparentes
habían desaparecido sobre todo si eran
menores de 2 mm. No hubo evidencia de
ninguna movilización no osteolisis en los
cotilos estudiados.
Resultados
No se ha perdido ningún paciente en el
seguimiento, ni se ha necesitado ninguna
otra cirugía en la cadera intervenida. Según
los criterios de Hodgkinson no hay signos
radiográfi cos de afl ojamiento en ningún componente
acetabular. No se ha comprobado
ningún problema por el uso de aumentos ni
por la realización de orifi cios extra, aunque
se discute que los debris que pueden caer
sobre la superfi cie interna del tantalio durante
la realización de éstos orifi cios extra puede
suponer un material a tener en cuenta (7).
Desde nuestro punto de vista estos problemas
se encontrarían disminuídos al recibir
posteriormente el cemento y el polietileno

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cementado.
Entre las complicaciones se han presentado
una infección superfi cial y dos luxaciones
perteneciendo éstas últimas a abordaje
posterior. No ha habido ninguna complicación
vásculo-nerviosa. En dos ocasiones y debido
a una muy mala calidad ósea (desartrodesis
y lupus) hubo que recurrir a la cementación
de otro componente acetabular.
Discusión
Los resultados tanto clínicos como radiográfi
cos, medidos con el HHS, con la mayoría
de las series utilizando cotilos ajustados a
presión son buenos. La serie presentada
es homogenea ya que utiliza el protocolo
establecido para este tipo de intervenciones
en un solo hospital.(10,11,12,13,14) La
mayoría de los pacientes de la serie han sido
intervenidos por dos cirujanos. La frecuencia
de líneas radiolúcidas en el postoperatorio
inmediato (40%), es similar al observado
en otras series (4). La presencia de zonas
radiolúcidas iniciales en la zona II, no es
predictivo de éxito o fracaso de la fi jación
acetabular, sino más bien consecuencia de
la técnica quirúrgica.
Los buenos resultados desde el punto
de vista clínico y radiográfi co, aunque el
seguimiento es corto puede explicarse por
la combinación de materiales y diseño del
implante acetabular que incluye la estabilidad
secundaria a la alta fricción del tantalio sobre
el hueso receptor, que además posee un
módulo de elasticidad similar al del hueso;
por lo que hace falta poder estudiar componentes
explantados y confi rmar la extensión
de osteointegración, lo mismo que el desgaste
del polietileno y la densidad mineral
ósea alrededor del implante.
Conclusiones
El componente acetabular de tantalio, tanto
para cirugía primaria, monobloque, como el
de dos piezas para cirugía de revisión que se
ha utilizado durante los cinco últimos años, ha
demostrado tener una excelente estabilidad
primaria y secundaria. No se han encontrado
líneas radio-transparentes, ni se ha desmontado
ninguna reconstrucción.
Con el acetábulo de revisión en dos piezas
y los aumentos del mismo radio, se puede
reconstruir cualquier defecto acetabular sin
recurrir a la utilización de injertos óseos.
Los autores hemos recibido ayuda económica
para la realización de éste trabajo del
Fondo de Investigación Sanitaria (Proyecto
FIS PI-04-1011, Instituto de la Salud Carlos
III, Ministerior de Sanidad y Consumo) dentro
del Programa de promoción de la Investigación
Biomédica y en Ciencias de la Salud,
en el marco del Plan nacional de Investigación
Científica, Desarrollo e innovación
Tecnológica (i+D+I) 2004-2007 co-fi nanciado
por el Fondo Europeo de desarrollo Regional
(FEDER).
Bibliografía.
1. Bobyn JD, Stackpool GJ, Hacking SA,
Tanzer M, Krygier JJ: “Characteristics of
bone ingrowth and interface mechanics
of a new porous tantalum biomaterial. J.
Bone Joint Sur. Br. 1999; 81:907-14.
2. Black J: “Biological Performance of
Tantalum”, Clinical Materials (1994) 16:
167-173.
3. Turner TM, Urban RM, Berzins A and Sumner
DR: “Evaluation of Tantalum Foam, a
Novel Porous Material for Bone Ingrowth
Fixation Using a Canine Model” 21 Annual
Meeting of the Society for Biomaterials.
1995 March 18-22. San Francisco. 125.
4.- Sculco TP.: “The Acetabular component:
an elliptical monoblock alternative”. J. Arthroplasty.
2002; 17 (Suppl 1):118-20.
5.- Gruen T, Christie MJ; Hanssen AD, et al:
“Radiographic evaluation of a non-modular
acetabular cup. A 2 to 5 year multi-center
study”. Presented as a poster exhibit at the
Annual Meeting of the American Academy
of Orthopaedic Surgeons; 2004 Mar 10-14;
San Francisco, CA.

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6. Lewis R et al. : “monoblock Trabecular Metal
Acetabulum. Two to Five Years Results”
70 th Annual Meeting of The American
Academy of Orthopaedic Surgeons, New
Orleans LA, February 5-7. 2003.
7. DeBoer DK and Stulberg D: Hedrocel
fosters bone ingrowth, permits strong soft
tissue attachment. Orthopaedics Today.
2000. Vol 3 nº1.
8. Bobyn JD, Boggie RA, Krygier JJ et al:
“Clinical validation of a structural porous
tantalum biomaterial for adult reconstruction”.
J. Bone Joint Surgery 2004; (Suppl
2) 86-A: 123-9.
9. Lewaleen D: “Use of porous tantalum in
Total Hip Arthroplasty”. HIP´ 2002: 229-
30. Toulouse.
10. Murcia A: “Trabecular Metal Technology
and clinical experience with the TMT revision
Cup and augments”. Internacional
Simposioum The Revision Acetabulum
Operative Management Problems. Charité
Campus Mitte. Berlín. January 2004.
11. Murcia A.: “Acetabular revision system:
surgical technique and early clinical experience”.
6th Congress of the European
Federation of National Associations of Orthopaedics
and Traumatology. (EFFORT)
Helsinki 2003.
12. Murcia A.: ”European ZMR Hip Masterclases
2004. Acetabular revision with
trabecular Metal”. Hospedale di Circolo.
Fondazione Macchi. Varese. Italia. April
2004.
13. Murcia A, Rodríguez L, Suárez MA et
al.: “TMT Cup in primary and revision Hip
Surgery”. 17 th Annual Symposium of the
International Society for Technology in
Arthroplasty. ISTA 2004. Roma.
14. Murcia A.: “Primary Hip Replacement with
Trabecular Metal” “Trabecular Metal in
revision Hip Arthroplasty”. Israeli Hip and
Knee Societies Meeting. Eilat. 2005.
REVISION SURGERY FOR
MEGA - DEFICIENCIES
INCLUDING NONUNIONS
OF THE ACETABULUM
R.Ganz
Orthopädische Universitätsklinik
Balgrist, Zürich, Switzerland
In revision surgery of the hip the extent of the
acetabular bone stock defi ciency frequently
exceeds the possibilities of autograft reconstruction.
To overcome such problems several
ways from bigger implants to allografting have
been attempted. However the more extreme
the defi ciency the more diffi cult and laborious
is the reconstruction.
Our experience using massive allograft reconstruction
was 50% component migration
in segmental defects but only 10% in cavitary
defects after 5 to 10 years. As a consequence
of this information we modifi ed the technique
of reconstruction by using autograft coverage
on allograft surfaces uncovered by host
bone.
The goal was to transform a segmental into
a cavitary defect. Especially in posterior defi -
ciencies and in transacetabular nonunions the
stabilisation of the bone reconstruction was
separated from the cup fi xation using plates
similar to acetabular fracture fi xation.
The paper illustrates the technical aspects
and reports on the results of a small group of
defi ciencies with pelvic discontinuity.

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THE DIAGNOSIS AND
MANAGEMENT OF
PERI-PROSTHETIC
INFECTIONS
P. McLardy-Smith,
B. Atkins, H. Pandit, T. Berendt,
N. Athanasou & the Oxford
Hip and Knee Group
Nuffi eld Orthopaedic Centre, Oxford, UK
Total hip replacement is probably the most
successful operation ever devised and other
joints, particularly the knee are now being successfully
replaced. However peri-prosthetic
infection remains a potentially catastrophic
complication. Infection rates are reported at
between 1- 2% and the risk of a peri-prosthetic
infection runs over the entire life time of the
joint. Peri-prosthetic infections can usefully
categorised as early acute or chronic and late
acute or chronic. The diagnosis of chronic
infections, particularly late ones, may be diffi
cult to achieve pre-operatively. Imaging techniques
and serological testing can be useful
but are not as yet reliable or specifi c. Aspiration
or closed biopsy are similarly unreliable.
Any joint revised for any reason may have an
underlying infection. In a prospective study
of 334 consecutive hip and knee revisions
we sent multiple samples from each case for
bacteriological and histological analysis. We
used the histological appearance as the criterion
for defi ning infection. By this defi nition
15% of infected cases were culture negative
and one positive culture specimen has no
predictive value for under lying infection. Two
or more positive cultures out of 5 or 6 samples
as a useful predictive value.
In acute infections, if the components are
soundly fi xed, salvage should be attempted
with adequate debridement sampling and
lavage of the joint. Arthroscopic washout in
Staphylococcal knee infections has a very
poor outcome. We would then recommend
long term antibiotic therapy. Salvage maybe
possible in chronic infections, but usually the
components are loose within the bone and a
full revision will be required. Frozen section
histological analysis of the tissue at the time
of surgery can differentiate septic from aseptic
loosening and maybe relied upon to choose
between a one or a two stage revision.
INFECTED TOTAL HIP
ARTHROPLASTY. ONE
STAGE REVISION
B. M. Wroblewski, P. D. Siney,
P. A. Fleming
The John Charnley Research Institute,
Wrightington Hospital, Hall Lane,
Appley Bridge Near Wigan U.K.
One of the most serious complications of
THA is deep infection. Charnley realised
the problem. This led to the development
of clean air enclosure, total body exhaust
suits and the introduction of the instrument
tray system. Subsequently antibiotics were
used both systematically and also as an addition
to the acrylic cement. Occasional deep
infection requires further intervention, either
by removing the implant, or performing one
or two stage revision. It has been the senior
author’s practice to undertake one-stage
revision provided the bone stock was of suffi
ciently good quality to ensure reasonable
quality of component fi xation. The technique
is based on the accepted principle of infection
management: Removal of all foreign body
material and infected tissues, application of local
antiseptics/antibiotics, closure of cavities,
ensuring stability, drainage, rest, continuation
of antibiotics.
Between January 1974 and December 2001,
185 one-stage revisions were carried out by
the senior author: 162 had a minimum fol-

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low-up of 5 years with a mean of 12.3 years
(5.1 – 27.6 years). 138 cases (85.2%) were
free from infection. Presence of a sinus at
revision did not affect the outcome adversely
– on the contrary - 90.4% were infection free
as compared with 82.7% of those without a
sinus. Attention to detail was the essential
part of the operation.

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11.45 - 13.30 h
RODILLA / KNEE
Unicompartimentales
Unicompartimentals
Moderador / Moderator: Peter McLardy-Smith
THE OXFORD EXPERIENCE
OF UNICOMPARTMENTAL
ARTHROPLASTY
P. McLardy-Smith & the Oxford
Hip and Knee Group
Nuffi eld Orthopaedic Centre, Oxford, UK
Introduction
Minimally invasive unicompartmental knee
replacement surgery is now very popular. It
is therefore important to know if this is safe
and effective. The aim of this study was to
determine the midterm results of the Oxford
unicompartmental knee implanted with a
minimally invasive approach.
Materials and Methods
This prospective study reports the complications
and survival of the fi rst 688 Phase
3 minimally invasive Oxford medial UKR
implanted by two surgeons and followed up
independently. None were lost to follow-up.
One hundred and thirty two of the replacements
were implanted over fi ve years ago.
The clinical assessment of 101 of these that
were available for review at fi ve years is also
presented.
Results
Nine of the 688 knees were revised: four
for infection, three for bearing dislocation
and two for unexplained pain. The survival
rate at seven years was 97.3% (CI: 5.3 %),
in addition seven knees (1%) required other
procedures: four MUAs, two arthroscopies
and one debridement for superfi cial infection.
At fi ve years, 96% of patients had a good or
excellent Knee Society rating, their average
Oxford knee score (OKS) was 39 and their
average fl exion was 133 0.
Conclusions
This study demonstrates that the minimally
invasive Oxford UKR is a reliable and effective
procedure.
UNI TKA – LONG
TERM FOLLOW UP
C. H. Rorabeck, MD
Health Sciences Centre, Ontario, Canada
Background:
Unicompartmental knee arthroplasty is experiencing
a resurgence in popularity worldwide.
The purpose of this study was to report our
experience with the Miller-Galante unicompartmental
knee arthroplasty at a mean 10
year follow-up in order to determine if this
procedure can provide durable long-term
clinical results.
Methods:
The study group consisted of 109 consecutive
Miller-Galante unicompartmental knee
arthroplasties in 83 patients performed by
two surgeons between 1989 and 1997. There
were 107 medial and two lateral compartment
arthroplasties performed. The mean age of

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the patients at the time of surgery was 67
years. Forty-four patients were male and
39 female. Nine patients died at a mean
of 6.6 years after the index arthroplasty. No
patients were lost to follow-up. The mean
duration of follow-up of the surviving patients
was 10.0 years.
Results:
At the time of the most recent follow-up, 11
medial compartment arthroplasties (10.3%)
and both lateral compartment arthropalsties
(100%) had been revised at a mean of 4.2
years. Of the 13 revision procedures, three
required use of revision components, and
none required bone graft or augments. The
mean Knee Society score for the surviving
patients who had not had a revision improved
from 100 points preoperatively to 172 points
at the most recent evaluation. Kaplan-Meier
survivorship analysis revealed a probability
of survival free of revision or radiographic
loosening of 93% at 5 years, and 86% at
10 years.
Conclusions:
The Miller-Galante unicompartmental knee
arthroplasty can provide reliable pain relief
and restoration of function in selected patients.
Our experience has shown that the
survivorship of this implant approaches that
of tricompartmental knee arthroplasty, and
suggests that it may offer the advantage of
ease of revision.
UNICONDYLAR KNEE
REPLACEMENT
D. Dalury
John Hopkins Hospital, Baltimore, USA
UKAs have enjoyed a minor resurgence in
popularity with increasing interest in miniincision
surgery. Newer implants, improved
instruments and better techniques have been
credited with the procedures new popularity.
While the classic UKA patient remains an
elderly, thin, female with minimal deformity
there has been more focus on utilization of the
UKA as an alternative to HTO, and TKA in the
younger patient. Early results with the newer
designed implants will be reviewed.
THE OXFORD KNEE
K. R. Berend, MD and A. V.
Lombardi, Jr, MD, FACS
Joint Implant Surgeons, Inc.; The
New Albany Surgical Hospital
The Ohio State University;
New Albany, Ohio, USA
Summary: At two years, obesity, young age,
and the presence of pre-operative anterior
knee pain do not appear to negatively impact
the outcome of Oxford UKA
Some believe the so-called “Oxford Indications”
for unicondylar arthroplasty are too
liberal. Much of the debate in the United
States centers on the performance of UKA
in severely obese patients, young patients,
and patients with anterior knee pain or patellofemoral
DJD. Since approval of the Oxford
UKA in 2004 we have performed over 300
cases using the Oxford criteria. The average
age of the patients was 62.4 years (range:
41-87; SD: 12) with 54% of patients under 60
years old. The average weight of the patients
is greater than 90 kg (range: 51-142; SD: 17
kg). In 64% the patient weight was greater
than 80 kg. The average BMI of the patients
was 31.6 (range: 21-48; SD: 6). 61% were
performed in patients considered obese with
a BMI greater than 30. In 25% of cases the
patients were categorized as morbidly obese
with BMI greater than 35. More than 40% of
UKA were performed in patients with a BMI
greater than 32, a category considered at risk
for failure secondary to obesity. 6% of patients

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complained of anterior knee pain, and 20%
complained of global knee pain. To date
we have had 5 implant failures: three tibial
loosening, one tibial fracture, and one infection.
One failure occurred in a patient with
severe obesity. No differences in outcomes
were observed in obese or young patients or
those with pre-operative patellofemoral DJD
or anterior knee pain. The Oxford Criteria
for UKA appear to be safe and accurate for
the use of this unconstrained mobile bearing
device. Signifi cantly fewer early failures
have been observed with this design even
in younger, obese patients with pre-existing
anterior knee pain or patellofemoral DJD than
with fi xed bearing designs.
RESURFACING UNI.
K. Steinbrink
Evangelisches Krankenhaus
Alsterdorf, Hamburg, Germany
OSTEOTOMY,
UNICOMPARTMENTAL
OR CONFORMIS
INTERPOSITIONAL
DEVICE (IPD)?
W. Fitz
Arthritis Center. Brigham & Woman’s
Hospital, MA, USA
Treatment options for unilateral symptomatic
osteoarthrosis of the knee in young and active
patients include osteotomy, unicompartmen-
tal or total knee replacement. Good long-term
results of fi xed metallic hemiarthroplasty have
been published for young patients using the
McKeever system (1-5). Unfortunately, the
McKeever system is no longer available.
In addition, the McKeever system was very
invasive requiring arthrotomy with large incision
size.
Mobile tibial hemiarthroplasty using the
Unispacer Knee has not demonstrated
comparable short-term results (6) and is not
recommended for the treatment of medial
osteoarthrosis (7,8).
A patient specifi c, personalized interpositional
device (iPD, Conformis, Foster City,
California) can offer an alternative for this
group of patients. This new device is currently
evaluated in a post-marketing, prospective
multi-center study.
Indications for this device include symptomatic
unilateral osteoarthrosis, mild valgus or
varus deformities, intact anterior cruciate
ligament, failure of non-operative treatment
and failure of biological repair in patients
who are not in favor or not a candidate for
an osteotomy or unicompartmental or total
knee arthroplasty.
Novel 3D image-to-implant sizing tools
are utilized to reconstruct the individual
cartilage from standard cartilage sensitive
MRI sequences. This data is utilized and a
patient specifi c device is manufactured and
inserted through a mini-arthrotomy after
arthroscopic resection of the posterior and
body of the menisus. Besides removal of
osteophytes , no bone resection is required,
thereby preserving all options for future implant
surgery.
Short-term results of 28 implants with a mean
follow-up of 6 months and, in some patients,
greater than two years are encouraging.
Mean OR time is 45 minutes, with experience
even less. Incision size ranges between 3 and
6 cm, with most cases between 4 and 5 cm.

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No dislocations have been observed. The
iPD provides the patient with normal, unrestricted
range of motion (ROM), comparable
to preoperative ROM.
This minimally invasive, bone and cartilage
preserving, patient specifi c device may provide
a surgical alternative to current surgical
alternatives, such as osteotomy, unicompartmental
or total knee replacement.
1. Scott RD, Joyce MJ, Ewald FC, Thomas
WH. McKeever metallic hemiarthroplasty
of the knee in unicompartmental degenerative
arthritis. Long-term clinical followup
and current indications. J Bone Joint
Surg Am. 1985;67:203-7.
2. Springer BD, Scott RD, Sah AP, Carrington
R. McKeever Hemiarthroplasty of the Knee
in Patients Less Than Sixty Years Old. J
Bone Joint Surg Am. 2006;88:366-371.
3. McKeever DC. Tibia plateau prosthesis.
Clin Orthop Relat Res. 1960;18:86-95.
4. Emerson RH Jr, Potter T. The use of the
McKeever metallic hemiarthroplasty for
unicompartmental arthritis. J Bone Joint
Surg Am. 1985;67:208-12.
5. MacIntosh DL. Hemiarthroplasty of the knee
using a space occupying prosthesis for painful
varus and valgus deformities. In: Proceedings
of the Joint Meeting of the Orthopaedic
Associations of the English-Speaking World.
J Bone Joint Surg Am. 1958;40:1431.
6. Hallock RH, Fell BM. Unicompartmental
tibial hemiarthroplasty: early results of the
UniSpacer knee. Clin Orthop Relat Res.
2003;416:154-63.
7. Scott RD. UniSpacer: insuffi cient data to
support its widespread use. Clin Orthop
Relat Res. 2003;416:164-6.
8. Sisto DJ, Mitchell IL: Unispacer Arthroplasty
of the Knee, J Bone Joint Surg Am.
2005;87:1706-1711.

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15.00 - 20.35 h
RODILLA / KNEE
Prótesis total de rodilla
Total knee arhroplasty
Moderadores / Moderators: Richard “Dickey” Jones, Francisco Gomar, Michael Freeman
THE MOVEMENT OF THE NORMAL TIBIO-FEMORAL JOINT
M. Freeman a,b,c, *, V. Pinskerova d
a Institute of Orthopaedics and Musculoskeletal Science, University College, London, UK
b School of Engineering Sciences, Southampton University, Southampton, UK
c The Royal London Hospital, London, UK
d First Orthopaedic Clinic, Charles University, Prague, Czech Republic

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THE ROLE OF
COMPUTER ASSISTED
SURGERY IN TRAINING
SURGEONS TO PERFORM TKA
D. Stulberg
Northwestern University Feinberg School
of Medicine - Chicago, Illinois, USA
FEMORAL COMPONENT
ROTATION IN TKA
J. D. Blaha, M.D.
University of Michigan.
Medical School. U.S.A
Placing total knee components in the proper
position in all three planes (frontal, sagittal
and transverse) is important for correct
functioning of the arthroplasty. Until relatively
recently little attention has been paid
to positioning in the transverse plane – often
referred to as the “rotational” position of components.
There has been acceptance of the
transepicondylar axis (TEA) is a landmark
by which the surgeon can align the femoral
component of a total knee replacement to
achieve proper rotation. Surgeons have
experienced problems, however, fi nding the
epicondyles with certainty making this set of
landmarks diffi cult to use, and there is some
concern that the epicondyles do not always
define a kinematically proper placement.
A line down the trochlear groove (AP axis
– most often attributed to Whiteside) has
been suggested as another guide to proper
rotational position.
In fact, the proper placement for a total knee
prosthesis is such that the axis of fl exion of
the component (i.e., the fl exion-extension
axis) is collinear with a functionally appropriate
fl exion axis for the patient’s knee. Kinematic
work with cadaver limbs has been used
to fi nd a functionally appropriate fl exion axis
for the knee. The knee joint moves in a plane
perpendicular to this fl exion-extension axis.
This functional plane is not coincident with
either the anatomic axis (i.e., shafts of the
bones) or the mechanical axis (i.e., femoral
head – center knee – center ankle). Rather
the plane intersects four critical functional
points: the lateral border of the acetabulum
(origin of the rectus femoris muscle), the
trochlear groove, the tibial tubercle and the
neck of the talus. These points now defi ne a
different axis for the knee joint: the functional
axis. Finding the functional axis will appropriately
position the components of a total knee
replacement so that the axis of the replaced
knee matches that of the native knee.
The AP clamp attaches to the femur at the
most posterior-superior part of the intercondylar
notch with an acutely curved portion
and to the trochlear groove with a more
gently curved portion. When used with an
appropriately angled intramedullary rod the
AP clamp establishes the plane perpendicular
to which a total knee femoral prosthesis
should be placed.

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SOURCES OF ERRORS IN
TOTAL KNEE ARTHROPLASTY:
THE IMPORTANCE OF
CAREFUL, ACCURATE
INTRA-OPERATIVE
MEASUEREMENT
D. Stulberg
Northwestern University Feinberg School
of Medicine - Chicago, Illinois, USA
EVOLUTION OF THE
CRUCIATE RETAINING TKA
V. M Goldberg, M.D
Department of Orthopaedics
Case Western Reserve University
University Hospitals of Cleveland
Cleveland, Ohio, USA
The function of the PCL includes transmission
of load, preventing posterior tibial subluxation
in fl exion, enhanced femoral rollback which
increases flexion, enhanced quadriceps
power and increased effi ciency in stair climbing.
The PCL provides primary and secondary
stability, enhanced proprioception and
reduced the shear stresses at the implant
interface. Additionally if one retains the PCL
the jointline is usually more easily maintained;
kinematics of the total knee replacement is
enhanced, and femoral bone stock may be
preserved. However, if the PCL is retained,
you must have optimum component design
and excellent surgical technique.
Critical in the femoral component design is
an optimal fi t of the femur reconstructing the
anterior-posterior dimensions of the medial
femoral condyle and duplicating the different
radius of curvatures of the lateral and
medial condyle for effective kinematics of
the knee. Tibial articulating geometry also
should support the knee rollback and rotation.
The sagittal plane resection (posterior slope)
of the tibial must also duplicate the patient’s
anatomy. Studies of stair climbing and walking
by Andriacchi, Dorr and Kelman indicate
the PCL-sparing knee replacements provide
an improved kinematic outcome for total knee
arthroplasty. Our own initial experience with
442 consecutive primary knees retaining the
posterior cruciate between August, 1989 and
June, 1994, demonstrated over 90% excellent/good
results with an average range of
motion of 112 degrees. With a minimum
twelve year follow-up there have been 20
revisions. (2 for loosening, 18 for wear/osteolysis).
A newer design to address the
issues of wear, enhance range of motion and
femoral-patellar function has been used since
1995. Our fi rst 104 PCL sparing knees for osteoarthritis
have been followed for 7-9 years.
The average Knee Score is 94.6, Function
score 88.9 and average range of motion of
117 degrees. There is a 100% survival of
these total knee replacements without any
pending revisions. There are still a number
of issues that require solution
These include: range of motion, better materials
for improved wear, enhanced soft
tissue balancing. and component position
and improved rate of recovery of the patient
Issues which have been resolved are fi xation,
instrumentation, alignment, excellent pain
relief and good function. Successful total
knee replacement still depends on patient
selection, implant design and post-operative
rehabilitation.

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FACTORS INFLUENCING
RANGE OF MOTION IN TKA.
THE RELATIONSHIP OF
ACCURATE IMPLANT
ALIGNMENT AND RANGE
OF MOTION IN TKA
SURGERY
D. Stulberg
Northwestern University Feinberg School
of Medicine - Chicago, Illinois, USA
HIGH FLEXION,
ROTATING PLATFORM
TOTAL KNEE ARTHROPLASTY:
RATIONALE, DESIGN, AND
PATIENT SELECTION
R. “Dickey” Jones, M.D.
U.T. Southwestern Medical Center,
Dallas, TX, USA
High fl exion in TKA is any fl exion beyond
125∞. High fl exion lifestyle activities such
as kneeling or praying are done with internal
rotation, external rotation, and in neutral.
Therefore, maximum fl exion TKA requires
a rotating platform. Superior range of motion
and fl uoroscopic kinematics of femoral
rollback have been shown with the Sigma
RP posterior stabilized knee. This knee
was modifi ed to reduce the Sigma RP-F, a
maximum fl exion knee, by adding a third
contact area at the post-cam mechanism
to signifi cantly increase bearing conformity
and decrease poly stresses in the range of
125-155. Clinical experience is reported
with statistically signifi cant increase in postoperative
range of motion in patients with
the Sigma RP-F. Patient selection criteria
for the Sigma RP-F include patients with
high fl exion lifestyle, younger, more active
patients demanding a better ROM, and those
patients with less than 100∞ preoperative
ROM. This knee system shows signifi cant
promise in providing maximum fl exion and
system longevity is expected.
FEMORAL COMPONENT
ROTATION: HOW TO
GET IT RIGHT?
D. A. Dennis, M.D.
Adjunct Professor, Dept. of Biomedical
Engineering, University of Tennessee
Assistant Clinical Professor, University
of Colorado Health Sciences Center
Clinical Director, Rocky Mountain Musculoskeletal
Research Laboratory
Denver, Colorado, USA
I. Why Component Rotation Matters
A. Malrotation Leads To:
1. Patellofemoral Maltracking
2. Disturbed Femorotibial Kinematics
a) Femoral Condylar Lift-Off
b) Flexion Instability
c) Enhanced Polyethylene Wear
3. Arthrofi brosis
II. Femoral Rotational Axes In TKA
A. Posterior Condylar Axis (PCA)
B. Anteroposterior Axis (APA)
C. Transepicondylar Axis (TEA)
1. Anatomic
2. Surgical
III. Femoral Component Rotation:

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Operative Techniques
A. Three Degrees External Rotation Relative
To The PCA
1. Advantages
a) Simple
b) Accurate In Most Knees With Limited
Deformity & Minimal Bone Erosion
2. Disadvantages
a) Anatomic Variations22
• TEA Externally Rotated Vs. PCA
(Average 3.6o)
• TEA Vs. PCA Range: 7o External
Rotation To 1o Internal Rotation
b) Less Reliable In Valgus Knees
(Hypoplastic Lateral Femoral
Condyle) 11,21
c) Can’t Use In Revision TKA
B. Parallel To Transepicondylar Axis
1. Advantages
a) Laboratory Studies Suggest TEA
Parallel To The Flexion – Extension
Axis and Perpendicular To The
Mechanical Axis
b) Enhances Central Patellofemoral
Tracking
c) Improved Tibiofemoral Kinematics
• Reduced Femoral Condylar
Lift-Off13
• Assists In Creation Of Rectangular
Flexion Gap21
d) TEA Available In Revision TKA
e) Accurate In Valgus Knees With
Hypoplastic Lateral Femoral
Condyles
2. Disadvantages
a) Often Difficult To Accurately Locate10,14,29,30
C. Perpendicular To The Anteroposterior
Axis
1. Advantages
a) Easy To Locate In Primary TKA3
b) Enhances Central Patellofemoral
Tracking 2,29
2. Disadvantages
a) Absent In Revision TKA
b) Less Reliable If:
• Severe Trochlear Dysplasia
• Advanced Patellofemoral Arthritis
(Trochlear Bone Erosion)
D. Flexion Gap Method
1. Femoral Component Placement Parallel
To Tibial Resection Surface With Equal
Collateral Ligamentous Tension
2. Advantages:
a) Better Flexion Stability / Reduced
Femoral Condylar Lift-Off
b) More Reproducable10
c) Available In Revision TKA
3. Disadvantages
a) Unreliable If Ligamentous Imbalance
Or Insuffi ciency
b) Unreliable If Inaccurate Tibial Resection
IV. Femoral Component Rotation:
SUMMARY
A. Advantages & Disadvantages Of Each
Technique
B. No Technique Is Perfect
C. Solution: Use All Available Methods
V. Tibial Component Rotation
A. Many Landmarks Utilized
1. Tibial Tubercle
2. Midcoronal Tibial Axis
3. Posterior Tibial Condylar Axis
4. Transmalleolar Axis
5. Second Metatarsal
6. Align With Femoral Component
B. No Single Landmark Highly Accurate
C. Good Scientifi c/Clinical Studies Lacking
D. Critical For Central Patellofemoral
Tracking
1. KEY – Don’t Internally Rotate ! ! !
BIBLIOGRAPHY
1. Akagi M, Matsusue Y, Mata T, Asada Y, Horiguchi
M, Iida H, Nakamura T: Effect of rotational
alignment on patellar tracking in total knee arthroplasty.
Clin Orthop, 366:155-163, 1999.
2. Anouchi YS, Whiteside LA, Kaiser AD Milliano
MT: The effects of axial rotational alignment of
the femoral component on knee stability and

Notas / Notes
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patellar tracking in total knee arthroplasty demonstrated
on autopsy specimens. Clin Orthop
287:170-171, 1993.
3. Arima J, Whiteside LA, McCarthy DS, White
SE: Femoral rotational alignment based on
the anteroposterior axis in total knee arthroplasty
in a valgus knee. A technical note. J
Bone Joint Surg, 77A:1331-1334, 1995.
4. Berger RA, Rubash HE, Seel MJ, Thompson
WH, Crossett LS: Determining the rotational
alignment of the femoral component in total
knee arthroplasty using the epicondylar axis.
Clin Orthop, 286:40-47, 1993.
5. Berger RA, Crossett LS, Jacobs JJ, Rubash
HE: Malrotation causing patellofemoral complications
after total knee arthroplasty. Clin
Orthop 356:144-153, 1998.
6. Bindelglass DF: Rotational alignment of the
tibial component in total knee arthroplasty.
Orthopedics, 24:1049-1052, 2001.
7. Bono JV, Roger DJ, Laskin RS, Peterson MG,
Paulsen CA: Tibial intramedullary alignment
in total knee arthroplasty. Am J Knee Surg,
8:11-12, 1998.
8. Demuth BC, Scuderi GR, Insall JN: The effect
of the epicondylar axis on patellar tracking
in TKA. American Academy of Orthopedic
Surgeons, Annual Meeting, San Francisco,
CA, February, 1997.
9. Engh GA: Orienting the femoral component
at total knee arthroplasty. Am J Knee Surg,
13:162-165, 2000.
10. Fehring TK: Rotational alignment of the
femoral component in total knee arthroplasty.
Clin Orthop, 380:72-79, 2000.
11. Griffi n FM, Insall JN, Scuderi GR: The posterior
condylar angle in osteoarthritic knees.
J Arthroplasty, 13:812-815, 1998.
12. Griffi n FM, Math K, Scuderi GR, Insall JN,
Poilvache PL: Anatomy of the epicondyles of
the distal femur. J Arthroplasty 15:354-359,
2000.
13. Insall JN, Scuderi GR, Komistek RD, Math
K, Dennis DA, Anderson DT: Correlation between
condylar lift-off and femoral component
alignment. Clin Orthop, (accepted).
14. Katz MA, Beck TD, Silber JS, Seldes RM
Lotke PA: Determining femoral rotational
alignment in total knee arthroplasty: Reliability
of techniques. J Arthroplasty, 16:301-305,
2001.
15. Maestro A, Harwin SF, Delvalle M, Caballero
D, Murcia A: Preoperative calculation of the
femoral transepicondylar axis: A combined
radiographic and mathematical method. Am
J Knee Surg, 13:181-187, 2000.
16. Mantas JP, Bloebaum RD, Skedros JG,
Hofmann AA: Implications of references axes
used for rotational alignment of the femoral
component in primary and revision knee arthroplasty.
J Arhtroplasty 7:531-535, 1992.
17. Miller MC, Berger RA, Petrella AJ, Karmas A,
Rubash HE: Optimizing femoral component
rotation in total knee arthroplasty. Clin Orthop,
392:38-45, 2001.
18. Miller MC, Zhang AX, Petrella AJ, Berger RA,
Rubash HE: The effect of component placement
on knee kinmatics after arthroplasty with
an unconstrained prosthesis. J Orthop Res.,
19:614-620, 2001.
19. Nagamine R, Miura H, Inoue Y, Urabe K,
Matsuda S, Okamoto Y, Nishizawa M, Iwamoto
Y: Relibility of the anteroposterior axis
and the posterior condylar axis for determining
rotational alignment of the femoral component
in total knee arthroplasty. J Orthop Sci, 3:194-
199, 1998.
20. Olcott CW, Scott RD: Determining proper
femoral component rotational alignment during
total knee arthroplasty. Am J Knee Surg,
13:166-168, 2000.
21. Olcott CW, Scott RD: A comparison of 4
intraoperative methods to determine femoral
component rotation during total knee arthroplasty.
J Arthroplasty 15:22-26, 2000.
22. Poilvache PL, Insall JN, Scuderi GR, Font-
Rodriguez DE: Rotational landmarks and
sizing of the distal femur in total knee arthroplasty.
Clin Orthop, 331:35-46, 1996.
23. Rhoads DD, Noble PC, Reuben JD, Tullos
HS: The effect of femoral component position
on the kinematics of total knee arthroplasty.
Clin Orthop, 286:122-129, 1993.
24. Scuderi GR, Insall JN: Rotational positioning
of the femoral component in total knee arthroplasty.
Am J Knee Surg, 13:159-161, 2000.

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25. Stiehl JB, Abbott BD: Morphology of the
transepicondylar axis and its application in
primary and revision total knee arthroplasty.
J Arthroplasty, 10:785-789, 1995.
26. Stiehl JB, Cherveny PM: Femoral rotational
alignment using the tibial shaft axis in total
knee arthroplasty. Clin Orthop, 331:47-55,
1996.
27. Tanavalee A, Yuktanandana P, Ngarmukos
C: Surgical epicondylar axis vs anatomical
epicondylar axis for rotational alignment of the
femoral component in total knee arthroplasty.
J Med Assoc Thai, 83 Suppl 1:S401-408,
2001.
28. Walker PS: A new concept in guided motion
total knee arthroplasty. J Arthroplasty, 16:157-
163, 2001.
29. Whiteside LA, Arima J: The anteroposterior
axis for femoral rotational alignment in valgus
total knee arthroplasty. Clin Orthop, 321:168-
172, 1995.
30. Yoshino N, Takai S, Ohtsuki Y, Hirasawa Y:
Computed tomography measurement of the
surgical and clinical transepicondylar axis
of the distal femur in osteoarthritic knees. J
Arthroplasty, 16:493-497, 2001.
LIGAMENT
BALANCING IN THE
VARUS KNEE
L. A. Whiteside, MD
Missouri Bone and Joint
Research Foundation
Missouri Bone and Joint Center
St. Louis, Missouri, USA
Medial stability of the knee is a complex
issue, and involves ligaments that behave
differently in flexion and extension. The
contracture and stretching that occur due
to deformity and osteophytes affect these
ligament structures unequally, and often
cause different degrees of tightness or
laxity in flexion and extension after the
bone surfaces are resected correctly for
varus-valgus alignment. The distortion of
alignment landmarks also can cause varusvalgus
alignment to differ in the flexed and
extended positions, and the knee thus may
require adjustment of portions of the medial
stabilizing complex that affects stability
either in flexion or extension.
The cornerstone to correct ligament balancing
is correct varus and valgus alignment in
fl exion and extension. For alignment in the
extended position, fi xed anatomic landmarks
such as the intramedullary canal of the femur
and long axis of the tibia are accepted. When
the joint surface is resected at an angle of
5° to 7° valgus to the medullary canal of the
femur and perpendicular to the long axis of
the tibia, the joint surfaces are perpendicular
to the mechanical axis of the lower extremity,
and roughly parallel to the epicondylar axis.
In the fl exed position, anatomic landmarks
are equally important for varus-valgus alignment.
Incorrect varus-valgus alignment in
fl exion not only malaligns the long axes of
the femur and tibia, but also incorrectly positions
the patellar groove both in fl exion and
extension.
Finding suitable landmarks for varus-valgus
alignment has led to efforts to use the posterior
femoral condyles, epicondylar axis, and
anteroposterior (AP) axis of the femur. The
posterior femoral condyles provide excellent
rotational alignment landmarks if the femoral
joint surface has not been worn or otherwise
distorted by developmental abnormalities or
the arthritic process. However, as with the
distal surfaces, the posterior femoral condylar
surfaces sometimes are damaged or
hypoplastic (more commonly in the valgus
than in the varus knee) and cannot serve as
reliable anatomic guides for alignment. The
epicondylar axis is anatomically inconsistent
and in all cases other than revision total
knee arthroplasty with severe bone loss,
is unreliable for varus-valgus alignment in
fl exion just as it is in extension. The AP axis,
defi ned by the lateral border of the posterior

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cruciate ligament posteriorly and the deepest
part of the patellar groove anteriorly, is
highly consistent, and always lies within the
median sagittal plane that bisects the lower
extremity, passing through the hip, knee,
and ankle. When the articular surfaces are
resected perpendicular to the AP axis, they
are perpendicular to the AP plane, and the
extremity can function normally in this plane
throughout the arc of fl exion.
In the presence of articular surface deformity
the anatomic references are especially important
for correct varus-valgus alignment.
The usual reliable landmarks for varusvalgus
alignment of the femoral component
in flexion include the posterior femoral
condyles, the long axis of the tibia, and the
tensed supporting ligaments. If the posterior
femoral condylar wears and the tibial plateau
collapses on the medial side of the knee,
these normally reliable landmarks cannot
be used. Instead, the AP axis of the femur
is used as a reference line for the femoral
cuts and the long axis of the tibia is used for
a reference line for the tibial cut so that the
joint surfaces are cut perpendicular to these
two reference lines. Once the joint surfaces
have been resected correctly to establish
normal varus-valgus alignment in fl exion and
extension, the trial components are inserted
and ligament function is assessed in fl exion
and extension. The ligaments are released
according to their function at each position.
The medial collateral ligament (deep and
superfi cial layers) attaches to the medial
epicondylar area through a broad band. The
posterior oblique portion, which spreads
posteriorly over the medial tibial fl are and
incorporates the sheath of the semimembranosus
tendon, tightens in extension. The
anterior portion of the ligament complex,
which extends anteriorly along the medial
tibial fl are, tightens in fl exion and loosens in
extension. The posterior capsule is loose in
fl exion, and tightens only in full extension.
With this information the medial ligament
structures of the knee can be released in-
dividually according to the position in which
excessive tightness is found.
The sequence in which the procedures are
performed is important in total knee replacement.
Resection of the femoral surfaces
makes the tibial surfaces accessible. Resection
of the tibial surface clears the way
to remove the osteophytes. Removal of
the osteophytes frees the ligaments so they
may be assessed and released as needed.
No ligament should be released until all the
osteophytes are removed otherwise excessive
laxity may occur. Extra bone should not
be removed to correct a fl exion contracture
until all ligament balancing has been fi nished,
otherwise inappropriate laxity in extension
may occur once ligament release has been
done.
The trial components are inserted before any
ligament releases are done, and the knee is
tested for stability in fl exion and extension.
With the trials in place, the knee is evaluated
in fl exion and extension to assess varus,
valgus, rotational, anterior and posterior
stability. Once the surgeon has determined
with certainty which ligaments are contracted,
limited releases can be done, releasing only
the ligaments that are tight and leaving alone
those that are not.
Tight Medially in Flexion, Loose Medially
in Extension
In some cases the medial structures are
not contracted uniformly, and the knee may
be tight medially only in fl exion, but not in
extension. The anterior portion of the medial
collateral ligament should be released fi rst.
This leaves the posterior oblique portion
intact to provide stability both in fl exion and
extension.
Tight in Extension, Balanced in Flexion
In some cases the posterior medial structures
are tight and the anterior MCL is normal after
insertion of the trial components. These
knees are tight in extension, but balanced
normally in fl exion. Knees that are tight only

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in extension after total knee arthroplasty fi rst
should have release of the posterior oblique
fi bers of the medial collateral ligament, and
release of the posterior capsule if medial contracture
persists in extension. This procedure
leaves the anterior portion of the medial collateral
ligament intact to stabilize the knee.
Tight Medially in Flexion and Extension
In many cases with a long-standing varus
deformity and medial ligament contracture,
the knee is tight medially both in fl exion and
extension. This indicates that the entire MCL
is contracted. The posterior capsule and PCL
also may be contracted, but the primary contracture
is the MCL in these cases. The PCL
and posterior capsule cannot be evaluated
until the MCL contracture has been corrected.
Knees that are tight in fl exion and extension
have release of the anterior and posterior portions
of the medial collateral ligament. This is
done by fi rst stripping the anterior portion of
the medial collateral ligament in line with the
tibial long axis, then directing the osteotome
posteriorly to release the posterior portion of
the ligament. Those knees that remain tight
in full extension after release of the posterior
oblique medial collateral ligament have
release of the posterior medial capsule from
the femur and tibia. If inappropriate posterior
femoral rollback occurs, or if medial ligament
tightness remains in fl exion after release of
the anterior portion of the medial collateral
ligament, the posterior cruciate ligament is
released from its tibial attachment.
Tight Popliteus Tendon
Occasionally the popliteus tendon and its surrounding
structures are tight in the varus knee
after the medial side has been corrected.
This often is diffi cult to detect, but rotational
stability testing of the tibia demonstrates that
the tibia is held anteriorly on the lateral side
and pivots around the lateral edge of the tibial
component. The popliteus tendon is released
from its bone attachment when the knee is
fl exed. It is found just distal and posterior
to the lateral collateral ligament (LCL) at-
tachment, and care must be taken to avoid
release of the LCL during this procedure.
Compensatory Lateral Release—Extension
Only
Occasionally, after full MCL release, the knee
is excessively loose on the medial side in
extension, and tight laterally. Compensatory
lateral release corrects the imbalance, and a
thicker tibial component brings the knee to
correct stability.
Compensatory Lateral Release—Flexion
and Extension
In some cases after full release of the MCL,
the secondary stabilizers are inadequate to
provide medial stability in fl exion and extension,
and the knee is too loose medially after
the tibial component has been sized to bring
the lateral ligaments to their normal tension.
In those cases the LCL and popliteus tendon
are released to create more laxity both in
fl exion and extension, and a thicker tibial
component is used to tension the medial
structures.
THE IMPACT OF
LIGAMENT BALANCING IN
TOTAL KNEE ARTHROPLASTY
J. Romero, M.D.
Endoclinic Zurich, Center for Arthroplasty
and Joint Surgery,
Klinik Hirslanden, Switzerland
Symmetrically balanced collateral soft tissues
in extension and in fl exion 1, 2 and alignment of
the tibial and femoral components perpendicular
to the mechanical axis in the coronal plane 3 are
major surgical goals in total knee arthroplasty.
Erroneous resection of the tibial plateau and
distal femoral condyles or inadequate soft tissue
release for varus or valgus contracture will result
in an asymmetric extension gap. Extension gap
imbalance due to insuffi cient soft tissue release
may cause polyethylene edge overload 4 and

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consequently accentuated wear 5 . Overrelease
of the collateral structures may result in symptomatic
instability 6 . Mild to moderate increased
varus-valgus laxity in extension has been reported
to be of no clinical importance 7 . However,
major instability may be an important cause for
total knee arthroplasty failure 8 and accounted
for 21% of 212 revision total knee arthroplasties
in the series by Sharkey et al .9 . Fehring et al. 10
reported on 27% instability cases in their total
knee revision population of 440 patients who
had to be revised after a follow-up of less than
5 years after primary TKA.
Increased varus or valgus laxity in fl exion
due to femoral component malrotation has
extensively been examined in cadaveric studies
under loaded 11 and unloaded conditions 12 .
Although femoral component malrotation is
considered the major cause for fl exion gap
imbalance 12,13 little is known on the clinical
consequences. Laskin 14 reported on patients
with medial tibial pain if the femoral
component was not externally rotated to
allow rectangularization of the fl exion gap.
Varus and valgus laxity in fl exion might be
diffi cult to quantify by clinical examination.
In a cadaver study, Grood et al. 15 compared
manually assessed medial and lateral
joint opening with varus and valgus laxity
determined by means of an Instron testing
system. They proved that erroneous laxity
assessment in fl exion is likely to occur by
clinical examination even when the primary
restraint is missing and the testing system
demonstrates a large joint opening. The application
of fl uoroscopic stress radiography on
a patient lying relaxed on a designated radiolucent
bench is a feasible, inexpensive, fast,
safe, and reproducible method for detecting
increased varus-valgus laxity of the knee in
fl exion on a routine base 16 . The moment applied
to the tibia has to be pain free avoiding
quadriceps and hamstrings cocontraction,
which increases tibiofemoral joint reaction
force and decreases joint opening 17 .
A recent study using a three-dimensional
interactive model-fi tting technique for twodimensional
fluoroscopic dynamic images
confi rms that increased femorotibial separation
(“condylar lift-off”) under weight-bearing
conditions in fl exion was more pronounced
on the lateral side, and was associated with
femoral component malrotation 18 . A study
by Stiehl et al. confi rms that condylar lift-off
occurs in clinically successful total knee
replacements 19 , but it is not known to what
extend this condition may be clinically tolerated.
An exaggerated condylar-lift off due to
increased lateral fl exion laxity because of a
malrotated femoral component may disturb
knee kinematics and ultimately accentuate
edge loading, which has been implicated as
a cause of premature polyethylene failure 20 .
A study using the WOMAC score as clinical
outcome measurement revealed that there are
specifi c symptoms associated with increased
fl exion gap imbalance due to internal femoral
component malrotation 21 . The predominant
patient complaints were pain on stair climbing,
reduced function on descending stairs and
raising from a chair, and diffi culties getting in
and out of a car or getting in and out of bath.
Attfi eld et al. 22 reported also on knees which
were not balanced in fl exion but fully balanced
in extension. Proprioception was reduced in
such knees compared to knees which were
properly balanced in fl exion and extension.
An important goal during surgey must be a
well balanced knee not only in extension but
also in fl exion. Proper femoral component
rotation reduces fl exion gap imbalance.
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13. Laskin RS: Flexion space confi guration in total
knee arthroplasty. J Arthroplasty 10:657, 1995
14. Grood ES, Stowers SF, Noyes FR: Limits of
movement in the human knee. J Bone Joint Surg
70-A: 88, 1988
15. Stähelin T, Kessler O, Pfi rrmann C, Jacob HAC,
Romero J: Fluoroscopically assisted stress
radiography for varus-valgus assessment in
fl exion after total knee arthroplasty. J Arthroplasty
18:513, 2003
16. Mac Williams BA, Wilson DR, Des Jardins JD,
Romero J, Chao EYS: Hamstrings cocontraction
reduces internal rotation, anterior translation, and
anterior cruciate ligament load in weight-bearing
fl exion. J Orthop Res 17:817, 1999
17. Insall JN, Scuderi GR, Komistek RD, Math K,
Dennis DA, Anderson DT: Correlation between
condylar lift-off and femoral component alignment.
Clin Orthop 403:143, 2002
18. Stiehl JB, Dennis DA, Komistek RD, Crane HS:
In vivo determination of condylar lift-off and screwhome
in a mobile-bearing total knee arthroplasty.
J Arthroplasty 14:293, 1999
19. Lewis P, Rorabeck CH, Bourne RB, Devane P:
Posteromedial tibial polyethylene failure in total
knee replacements. Clin Orthop 299:11, 1994
20. Romero J, Stähelin T, Binkert C, Pfi rrmann CW,
Hodler J, Kessler O: The clinical consequences of
fl exion gap asymmetry in total knee arthroplasty.
J Arthroplasty, in press
21. Attfi eld SF, Wilton TJ, Pratt DJ, Sambatakakis A:
Soft-tissue balance and recovery of proprioception
after total knee replacement. J Bone Joint
Surg 78-B:540, 1996
LIGAMENT BALANCING
IN THE VALGUS KNEE
L. A. Whiteside, MD
Missouri Bone and Joint
Research Foundation
Missouri Bone and Joint Center
St. Louis, Missouri, USA
The cornerstone to correct ligament balancing
is correct varus and valgus alignment in
fl exion and extension. For alignment in the
extended position, fi xed anatomic landmarks
such as the intramedullary canal of the femur
and long axis of the tibia are accepted. When
the joint surface is resected at an angle of
5° to 7° valgus to the medullary canal of the
femur and perpendicular to the long axis of
the tibia, the joint surfaces are perpendicular

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to the mechanical axis of the lower extremity,
and roughly parallel to the epicondylar axis.
In the fl exed position, anatomic landmarks
are equally important for varus-valgus alignment.
Incorrect varus-valgus alignment in
fl exion not only malaligns the long axes of
the femur and tibia, but also incorrectly positions
the patellar groove both in fl exion and
extension.
Finding suitable landmarks for varus-valgus
alignment has led to efforts to use the posterior
femoral condyles, epicondylar axis, and
anteroposterior (AP) axis of the femur. The
posterior femoral condyles provide excellent
rotational alignment landmarks if the femoral
joint surface has not been worn or otherwise
distorted by developmental abnormalities or
the arthritic process. However, as with the
distal surfaces, the posterior femoral condylar
surfaces sometimes are damaged or
hypoplastic (more commonly in the valgus
than in the varus knee) and cannot serve as
reliable anatomic guides for alignment. The
epicondylar axis is anatomically inconsistent
and in all cases other than revision total
knee arthroplasty with severe bone loss,
is unreliable for varus-valgus alignment in
fl exion just as it is in extension. The AP axis,
defi ned by the lateral border of the posterior
cruciate ligament posteriorly and the deepest
part of the patellar groove anteriorly, is
highly consistent, and always lies within the
median sagittal plane that bisects the lower
extremity, passing through the hip, knee,
and ankle. When the articular surfaces are
resected perpendicular to the AP axis, they
are perpendicular to the AP plane, and the
extremity can function normally in this plane
throughout the arc of fl exion.
In the valgus knee with signifi cant posterior
deformity or erosion, the posterior femoral
condyles are unreliable as rotational alignment
landmarks, and the anteroposterior axis
provides a reliable landmark for rotational
alignment of the femoral surface cuts.
Technique for Femoral Bone Resection
Intramedullary alignment instruments usually
are used for the femoral resection. The
distal femoral surfaces are resected at a
valgus angle of 5-7°. A medialized entry
point generally is advised because the distal
femur curves toward valgus in the valgus
knee. The current technique is to reference
the resection from the distal medial femoral
surface. The distal femoral cutting guide is
seated on the distal surface of the medial
femoral condyle, which is resected equal to
the thickness of the distal condylar surface
of the implant. If the distal lateral femoral
condylar surface is defi cient, considerably
less is resected from the lateral surface than
from the medial surface, and in many cases
of a severe valgus angle, no bone is present
to resect from the distal lateral surface.
Seating on bone is necessary on the lateral
distal side, but this can be accomplished with
the anterior lateral bevel surface. In cases
of severely defi cient lateral femoral condylar
bone stock, the anterior bevel surface is the
only bony contact for the distal lateral surface
of the femoral component. This leaves a gap
that is fi lled with bone graft between the distal
bone surface and the inner surface of the implant
on the lateral side. When the posterior
fl ange and the anterior bevel surfaces are
seated on viable bone, the distal defect can
be treated as a contained defect and needs
no structural grafting. Rotational alignment of
the distal femoral cutting guide is adjusted to
resect the anterior and posterior surfaces perpendicular
to the anteroposterior axis of the
femur. The AP axis is drawn and the femoral
cutting guides are aligned to make the cuts
perpendicular to this line. In the valgus knee
this almost always results in much greater
posteromedial than posterolateral femoral
condylar resection.
Technique for Tibial Bone Resection
Intramedullary alignment instruments are
used to real tibial surface is based on the
height of the intact medial bone surface. A
maximum thickness of 10 mm is removed

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from the medial tibial plateau, which often
leaves the defect on the lateral side of the
tibia that requires a bone graft. Use of a
long-stem tibial component and screws in
the tibial tray securely fi xes the tibial component,
and obviates the use of fi xed structural
bone graft.
Ligament Release Technique and Differential
Balancing
Stability is assessed fi rst in fl exion by holding
the knee at 90° fl exion and maximally
internally rotating the extremity to stress
the medial side of the knee, then maximally
externally rotating the extremity to evaluate
the lateral side of the knee. A medial opening
greater than 4 mm, and a lateral opening
greater than 5 mm, is considered abnormally
lax, whereas an opening less than 2 mm on
either side is considered abnormally tight.
The knee then is extended and stability is assessed
in full extension by applying varus and
valgus stress to the knees. A medial opening
greater than 2 mm and a lateral opening
greater than 3mm is considered abnormally
lax, whereas an opening less than 1 mm on
either side is considered abnormally tight.
Tight laterally in fl exion only
In knees that are too tight laterally in fl exion,
but not in extension, the LCL is released in
continuity with the periosteum and synovial
attachments to the bone. When this lateral
tightness is associated with internal rotational
contracture, the popliteus tendon attachment
to the femur also is released. The iliotibial
band and lateral posterior capsule should not
be released in this situation because they
provide lateral stability only in extension.
Tight laterally in fl exion and extension
The only structures that provide passive stability
in fl exion are the LCL and the popliteus tendon
complex, so knees that are tight laterally in
fl exion and extension have popliteus tendon or
LCL release (or both). Stability is tested after
adjusting tibial thickness to restore ligament
tightness on the lateral side of the knee. Ad-
ditional releases are done only as necessary
to achieve ligament balance. Any remaining
lateral ligament tightness usually occurs in the
extended position only, and is addressed by
releasing the iliotibial band fi rst, then the lateral
posterior capsule if needed. The iliotibial band
is approached subcutaneously and released
extrasynovially, leaving its proximal and distal
ends attached to the synovial membrane.
Tight laterally in extension only
In knees that initially are too tight laterally
in extension, but not in fl exion, the LCL and
popliteus tendon are left intact, and the
iliotibial band is released. If this does not
loosen the knee enough laterally, the lateral
posterior capsule is released. The LCL and
popliteus tendon rarely, if ever, are released
in this type of knee.
Finally, the tibial component thickness is
adjusted to achieve proper balance between
the medial and lateral sides of the knee. Anteroposterior
stability and femoral rollback are
assessed, and posterior cruciate substitution
is done if necessary to achieve acceptable
posterior stability.
MEDIAL PIVOT KNEE
ARTHROPLASTY
J. D. Blaha, M.D.
University of Michigan.
Medical School, USA
Design of total knee prostheses is predicated
on knowledge of the kinematics of the normal
knee. Designs that more closely mimic the
normal might reasonably be expected to perform
more normally for the patient. For many
years the knee joint has been viewed as a
“four-bar link” in which the ligaments (specifi -
cally the cruciate ligaments) guide the motion
of the knee in such a way that “rollback” occurs.
(Rollback is the progressive posterior

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movement of the contact point between the
femur and the tibia with increasing fl exion.)
Proponents of the four-bar link model point to
studies that have shown a decreasing radius
of curvature of the femoral condyles from
distal to posterior.
Several recent studies of knee joint kinematics
have suggested that the knee can be
modeled as having a single axis of fl exionextension.
Similarly, the internal and external
rotation of the tibia around the femur (i.e.,
the pivot) of the knee can be modeled by an
axis roughly at the central part of the medial
condyle. (van Dijk et al. 1983, Blankevoort et
al. 1988, Hollister et al. 1993, Mancinelli et al.
1994, Blaha et al. 2003) These studies show
that the normal knee does not roll-back, but
rather remains remarkably constant in position
on the medial side (like a ball in a socket)
while varying in contact position on the lateral
side to accommodate internal and external
rotation of the tibia about the femur.
Kinematic studies of total knee prostheses
designed respecting the concept of the “fourbar
link” and providing for roll back have demonstrated
paradoxical kinematics. Instead of
rolling back, these knees demonstrate sliding
forward of the femur on the tibia during in
vivo fl uoroscopic studies. A similar kinematic
study done with a knee joint designed for medial
pivot and medial ball-in-socket kinematics
does not demonstrate paradoxical motion.
(Banks et al. 1997, Dennis et al 1997, Blaha
et al. 1998)
The Advance“ Medial-Pivot (Wright Medical
Technology, Arlington TN USA) total knee
prosthesis has been in clinical use for 5
years (as of January, 2003). Based on the
preliminary results available at the time of
the writing of this abstract the medial ball-insocket
confi guration of the implant appears
to provide a clinical result characterized by
enhanced anterior-posterior stability both to
clinical examination and in functional use.
ROTATION IS THE FINAL
SOLUTION: MOBILE
BEARING TOTAL KNEE
R. “Dickey” Jones, M.D.
U.T. Southwestern Medical Center,
Dallas, TX, USA
Surface wear in TKA remains a problem
producing sub-micron wear particles which
accumulate in periprosthetic tissue leading to
cytokinin release and osteolysis. A physiological
knee joint simulator was used to compare
fi xed bearing to a rotating platform design of
the same knee system. Despite similar contact
areas the rotating platform bearings had
4 times less wear under high kinematics than
the fi xed bearings. Polyethylene orientates
in the principle direction of sliding and strain
hardening with strength increase occurs parallel
to sliding, but is reduced transverse to
sliding. In fi xed bearings the increased multidirectional
motion of the femoral component
relative to the bearing produces the multi-axial
wear path, transverse friction forces and gives
higher wear. With the Rotating Platform,
rotation occurs at the tibial tray, diminishing
multi-directional motion at the femoral
interface, converting to uni-directional wear
paths, decreasing transverse friction forces
and producing signifi cantly lower wear. With
higher kinematic inputs fi xed bearing TKAs
show a fi ve fold increase in surface wear over
lower inputs. The Rotating Platform produced
94% less wear than the fi xed bearing over 6
million cycles.
Dynamic kinematic fluoroscopic studies
confi rm the Rotating Platform moves with
the femoral component and axial rotation
occurs on the inferior aspect. The Rotating
Platform accommodates to the patient’s gait
kinematics, enhancing positive bone and soft
tissue remodeling.

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All mobile bearings are not the same.
TKAs with rotation and AP translation produce
more surface wear.
Benchtop and analytical studies suggest
rotating platform knee designs offer system
longevity. The excellent 20-year LCS-RP
survivorship provides clinical confi rmation.
PS FIXED OR MOBILE?
DOES IT MATTER?
H. P. Delport
Head Department of Orthopaedics.
AZ Wassland Sint Niklaas. Belgium
Mobile-bearing posterior stabilised knee
replacements have been developed as an
alternative to the standard fi xed- and mobilebearing
designs.
However little is known about the in vivo kinematics
of this new group of implants.
We investigated 31 patients who had undergone
a TKR with a similar design but with 3 different
options : fi xed-bearing posterior cruciate
ligament-retaining, fi xed-bearing posterior-stabilised
and mobile-bearing posterior-stabilised.
To do this we used a three-dimensional to twodimensional
model registration technique.Both
the fi xed- and mobile-bearing posterior stabilesed
confi gurations used the same femoral
component. We found that fi xed-bearing posterior-stabilised
and mobile-bearing posteriorstabilised
knee replacements demonstrated
similar kinematic patterns,with consistent
femoral roll-back during fl exion.Mobile-bearing
posterior-stabilised knee replacements demonstrated
greater and more natural internal
rotation of the tibia during fl exion thanfi xedbearing
posterior-stabilised designs.
Such rotation occurred at the interface between
the insert and the tibial tray for mobile-
bearing posterior-stabilised designs.
However, for fi xed-bearing posterior-stabilised
designs, rotation occurred at the proximal
surface of the bearing.
Posterior cruciate ligament-retaining knee
replacements demonstrated paradoxical
sliding forward of the femur.
We concluded that mobile-bearing posteriorstabilised
knee replacements reproduce internal
rotation of the tibia more closely during
fl exion than fi xed-bearing posterior-stabilised
knee designs.
Furthermore, mobile-bearing posterior-stabilised
knee replacements demonstrate a unidirectional
movement which occurs at the upper and lower
sides of the mobile inserts. The femur moves
in an anteroposterior direction on the upper
surface of the insert, whereas the movement
at the lower surface is pure rotation.
Such unidirectional movement may lead to
less wear when compared with the multidirectional
movement seen in fi xed-bearing
posterior-stabilised knee replacements and
should be associated with more evenly applied
cam-post stresses.
MOBILE BEARINGS:
ARE THEY WORTH IT?
P. Bonutti, MD
Effi ngham, IL, USA
Mobile Bearing is a technology which adds
additional cost to Knee Arthroplasty. Are
there added clinical benefi ts to justify this
cost? Numerous factors have been suggested
to add clinical value in MB TKA.
However, a critical review of clinical data may
not support this. Alleged clinical benefi ts for
MB TKA include:
1) “The only knee that bends and rotates”

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- False.
2) Improved function - Not accurate.
3) Improved ROM - False.
4) Improved long term survivorship - unproven.
5) Reduced polyethylene wear - not proven
in in vivo studies.
6) Improved patellofemoral tracking - inaccurate.
7) “Surgical forgiveness” - actually more
challenging.
In addition, MB TKA may have additional
complications not found in fi xed bearings
such as bearing subluxations, dislocations,
and insert fractures.
Two recent clinical studies have suggested
possible functional benefi t which may be implant
design specifi c. Ball et al (2006) found
with the Scorpio MB TKA, improved stair
climbing ability. Delport et al (2006) with a
kinematic analysis found Biomet performance
MB TKA reproduces internal rotation of the
tibia more closely during fl exion.
MB TKA theoretical advantage possibly may
be very design specifi c, but the majority of
literature does not prove clinical benefi t associated
with MB TKA. Based on current
review MB TKA is not worth it.

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Notas / Notes
Viernes, 1 de diciembre
Friday, 1st December
md
RODILLA / KNEE
Protesis total de rodilla
MIS y PTR
MIS y navegación
Complicaciones
Rodilla de revisión
Total knee arhroplasty
TKA and MIS
MIS and navigation
Complications
Revision knee
Moderadores / Moderators: Joan Nardi, Carlos Resines, Michael Freeman,
Leo Whiteside, Carlos Rodríguez-Merchán, David Dalury
VIERNES / FRIDAY
251

VIERNES / FRIDAY
252
08.30 - 11.00 h
RODILLA / KNEE
Prótesis total de rodilla
Total knee arhroplasty
Moderador / Moderator: Joan Nardi
ARTHROSCOPIC
PATELLOPLASTY
R. Jones, M.D.
U.T. Southwestern Medical Center,
Dallas, TX, USA
Introduction
Treatment of isolated, severe patella femoral
arthrosis has been controversial. The
hypothesis that arthroscopic lateral patella
facetectomy would provide symptomatic relief
was tested.
Methods
Thirty-nine consecutive patients (age range
41 to 80 years) were evaluated pre and postoperatively
for pain at rest, while rising from a
seated position, and while stair climbing. All
patients underwent arthroscopic lateral patella
facetectomy and had increased patella
excursion after the decompressive operation.
Pre and postoperative radiographs were
obtained. Pain scores were evaluated on a
visual analog scale.
Results
The patients had increased patella excursion
after the operation. The postoperative
radiographs confi rmed removal of the overriding
lateral facet and decompression of the
compartment. The paired T-test was used to
analyze the data collected. Signifi cant pain
relief (p

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shallow patellar groove and wide intercondylar
notch. Those with deeper patellar grooves
and supporting lateral fl ange surfaces had
low contact stress similar to that of the normal
patellofemoral joint. This suggests that the
variation in the reported clinical results of not
resurfacing the patella could be explained
by the differences in design features of the
femoral component.
A clinical and laboratory study was done to
test the hypothesis that reported differences
in clinical results of unresurfaced patellae
in total knee arthroplasty are due to differences
in design of the femoral component.
Thirty-eight knees had an Ortholoc II femoral
component (shallow patellar groove, wide
intercondylar notch, and fl at femoral surface).
Thirteen knees had severe and three
had moderate anterior knee pain. Fifteen
required patellar resurfacing later. Two hundred
twenty-two knees had Advantim femoral
components (deepened and extended
patellar groove, narrow intercondylar notch,
and rounded femoral surfaces). None of
these knees had severe anterior knee pain.
Eighteen percent had mild anterior knee pain
on stairs postoperatively. Three hundred
thirty knees had Profi x femoral components
(deepened and extended patellar groove,
rounded femoral surfaces, and extended
lateral patellar support). Ten percent of Profi x
knees had mild anterior knee pain. This rate
was statistically signifi cantly less than that of
the knees with Advantim femoral components
(p

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sive lateral facet resection)
2. Treatment (based on etiology)
a. Lateral retinacular release / VMO
advancement
b. Tibial tubercle transfer
c. Capsular repair
d. Component revision if malpositioned
3. Intraoperative analysis
a. Rule of No Thumb
b. Release of tourniquet to assess extensor
mechanism balance
B. Patellar Fracture
1. Multiple etiologies
a. Trauma
b. Improper patellar resection (excessive,
insuffi cient, asymmetric)
c. Large central fi xation lug
d. Patellofemoral instability (eccentric
loading)
e. Avascular necrosis
1) Intraosseous / extraosseous vascular
disruption
2) Prevention
a) Maintain fat pad and LSGA
b) Avoid large central lug hole
f. Excessive fl exion (increased loads /
activity levels)
g. Component malposition
h. Thermal necrosis (PMMA)
2. Treatment
a. Nonoperative
1) Nondisplaced fractures
2) Displaced without extensor lag
3) No dislocation / loosening
b. Operative
1) Displaced with extensor lag
2) Poor results
C. Patellar Component Loosening
1. Etiologies
a. Instability
b. Cementation into defi cient bone
c. Excessive body weight / activity levels
2. Treatment
a. Observation
b. Component revision or removal
c. Patellectomy
D. Patellar Component Failure
1. Polyethylene wear / fracture
a. Contact pressures routinely exceed
UHMWPE yield strength
b. Malalignment = Increased loads
c. Metal backing = reduced polyethylene
thickness
2. Polyethylene/plate dissociation
a. No chemical bonding
b. Excessive wear / loss of mechanical
grip
3. Peg/plate dissociation
a. Good peg ingrowth
b. Variable plate ingrowth
c. High shear @ peg/plate junction
4. Multiple clinical studies
a. Metal-backed failures predominate
b. Often unsuspected preoperatively
c. Failure with multiple designs
d. Early failure common (2 to 4 years)
e. Be prepared to revise all components
if metal-backed design present
1) Femoral/tibial component damage
often coexisting
5. Risk factors
a. Excessive body weight/activity levels
b. Enhanced knee fl exion (>115°)
c. Male gender
d. Patellofemoral malalignment
e. Oversized/flexed femoral components
f. Joint line malposition
E. Patellar Clunk Syndrome
1. Anterior “clunk” on knee extension @
30-45°
2. Suprapatellar nodule - catches in intercondylar
notch
3. Pathogenesis: quadriceps tendon impingement
a. Small patellar component
b. Superior component malposition
c. Abrupt change in radius of curvature
of femoral component
d. Sharp superior edge (intercondylar
notch)
4. Treatment
a. Nodule excision (open vs. arthroscopic)
b. Patellar component revision (cau-

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dad)
F. Tendon Rupture
1. Quadriceps - increased risk with LRR
2. Patellar - increased risk with revision
TKA
a. Revision TKA
b. Partial tendon release
c. Closed knee manipulation
d. Tibial tubercle osteotomy nonunion
3. Key is PREVENTION
a. Consider quadricepsplasty vs. tibial
tubercle osteotomy
4. Treatment
a. Results usually poor
b. Multiple methods
c. Extensor mechanism allograft
III SURGICAL TECHNIQUE
A. Measure patella and component thicknesses
B. Remove what you replace
C. Thickness - try to maintain 15 mm
D. Measure thickness / symmetry postresection
E. Ensure proper component (patellar, tibial,
femoral) position
F. Ensure central patellar tracking
1. Following tourniquet release
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26. Grace JN, Sim RH: Fracture of the patella
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230:168, 1988.
27. Hofmann GO, Hagena FW: Pathomechanics
of the femoropatellar joint following
total knee arthroplasty. Clin Orthop. 224:25
1, 1987.
28. Hollander A, Burny F, Monteny E, Donkerwolcke
M: Extra-osseous variation
of temperature during polymerization of
acrylic cement in hip arthroplasties. Acta
Orthop Scand 47:186, 1976.
29. Homsy CA: Some Mechanical Aspects of
Methyl-Methacrylate Prosthesis Sealing
Compound. St. Louis, Mosby, 1973.
30. Hozack WJ, Goll SR. Lotke PA, Rothman
RH, Booth RE Jr: The treatment of patellar
fractures after total knee arthroplasty. Clin
Orthop 236:123, 1988.
31. Hozack WJ, Rothman RH, Booth RE Jr,
Balderston RA: The patellar clunk syndrome;
a complication of posterior stabilized
total knee arthroplasty. Clin Orthop
241:203, 1989.
32. Huberti HH, Hayes WC: Patellofemoral
contact pressure; the infl uence of Q angle
and tendofemoral contact. I Bone Joint
Surg 66A:714, 1984.
33. Hungerford DS, Barry M: Biomechanics
of the patellofemoral joint. Clin Orthop.
1979; 144:9.
34. Insall JN: Disorders of the patella. In
Insall IN (ed): Surgery of the Knee. New
York NY, Churchill Livingstone, 1984, pp.
119-260.
35. Insall JN, Tria AJ, Aglietti P: Resurfacing
of the patella. I Bone Joint Surg 62A:933,
1980.
36. James DSS, Scott R Extensor mechanism
complications. In Rand IA (ed.): Total
Knee Arthroplasty. New York NY, Raven
Press, 1993, pp. 393-402.
37. Jones BC, Insall JN, Inglis AE, Ranawat
CS: GUEPAR knee arthroplasty results
and late complications. Clin Orthop
140:145, 1979.
38. Josefchak RG, Finlay JB. Bourne RB,
Rorabeck CH: Cancellous bone support
for patellar resurfacing. Clin Orthop
220:192, 1987.
39. Kaufer H: Mechanical function of the patella.
J Bone Joint Surg 53A: 1551, 1971.
40. Kayler DE, Lyttle D: Surgical interruption
of patellar blood supply by total knee arthroplasty.
Clin Orthop 229:221, 1988.
41. Leblanc JM: Patellar complications in
TKA: a literature review. Orthop Rev

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18:296, 1989.
42. Levai JP, McLeod HC, Freeman MAR:
Why not resurface the patella. J Bone Joint
Surg 65B:448, 1983.
43. Lynch AF, Rorabeck CH, Bourne RB:
Extensor mechanism complications following
total knee anthroplasty. J Arthroplasty
2:135, 1987.
44. Matthews L: Load Bearing Characteristics
of the Patellofemoral Joint. AAOS Symposium
on Reconstructive Surgery of the
Knee. St. Louis, Mosby, 1978, p. 326.
45. McMahon MS, Scuderi OR, Glashow JL et
al: Scintigraphic determination of patellar
viability after excision of infrapatellar fat
pad and/or lateral retinacular release in
total knee anthroplasty. Clin Orthop 260:
10, 1990.
46. Merkow RL, Soudry M, Insall JN: Patellar
dislocation following total knee replacement.
J Bone Joint Surg 67A:1321,
1985.
47. Mochizuki RM, Schurman DJ: Patellar
complications following total knee arthroplasty.
J Bone Joint Surg. 61A:879,
1979.
48. Morrison .JB: The forces transmitted by
the human knee joint during activity. Thesis,
University of Strathclyde, Scotland,
1967.
49. Picatti GD, McGann WA, Welch RB: The
patellofemoral joint after total knee arthroplasty
without patellar resurfacing. J Bone
Joint Surg 72A: 1379, 1990.
50. Rae PJ, Noble J, Hodgkinson JP: Patellar
resurfacing in total condylar knee
arthroplasty. Technique and results. J
Arthroplasty 5:259, 1990.
51. Ranawat CS: The patellofemoral joint in
total condylar knee arthroplasty pros and
cons based on 5-10 year follow-up observations.
Clin Orthop 205:93, 1986.
52. Ranawat CS, Rose HA, Bryan JW:
Technique and results of patellofemoral
joint with total-condylar knee arthroplasty.
Orthop Trans 6:88, 1982.
53. Rand JA: Patellar resurfacing in total knee
arthroplasty. Clin Orthop 260:110,1990.
54. Rand JA, Chao EY, Stauffer RN: Kinematic
rotating hinge total knee arthroplasty. J
Bone Joint Surg69A:489, 1987.
55. Rand JA, Gustilo RB: Technique of patellar
resurfacing in total knee arthroplasty.
Tech Orthop.133:57, 1988.
56. Rand JA, Morrey BF, Bryan AS: Patellar
tendon rupture after total knee arthroplasty.
Clin Orthop244:233, 1989.
57. Reilly TB., Martens M: Experimental
analysis of the quadriceps muscle force
and patellofemoral joint reaction force
for various activities. Acta Orthop Scand
43:126, 1972.
58. Reuben JD, McDonald L, Woodard PL,
Hennington U: The effect of patella thickness
on patella strain following total knee
replacement. Presented at 57th Annual
Meeting of the AAOS, New Orleans,
1990.
59. Roffman M, Hirsh DM, Mendes DG: Fracture
of the resurfaced patella in total knee
replacement Clin Orthop 148:112, 1980.
60. Rosenberg AG, Andriacchi TP, Barden R,
Galante JO: Patellar component failure in
cementless total knee arthroplasty. Clin
Orthop 236:106, 1988.
61. Scapinelli R: Blood supply of the human
patella. J Bone Joint Surg 49B:563,
1967.
62. Scapinelli R Studies on the vasculature
of the human knee joint Acta Anat (Basel)
70:305, 1968.
63. Scott RD: Prosthetic replacement of the
patellofemoral joint. Orthop Clin North Am
10: 129, 1979.
64. Scott WN, Rozbruch JD, Otis JC et al:
Clinical and biomechanical evaluation of
patella replacement in total knee arthroplasty.
Orthop Trans 2:203, 1978.
65. Scott RD. Turoff N, Ewald FC: Stress
fracture of the patella following duopatellar
total knee arthroplasty with patellar resurfacing.
Clin Orthop 170:147, 1982.
66. Scuderi G, Scharf SC, Meltzer LP, Scott
WN: The relationship of lateral releases to
patella viability in total knee arthroplasty.
J Arthroplasty 2:209, 1987.

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67. Scuderi GR, Insall, JN, Scott WN: Patellofemoral
pain after total knee arthroplasty. J
Am Acad Orthop Surg 2:239-246, 1994.
68. Soudry M, Mestiner LA, Binazzi R, Insall
JN: Total knee replacement without patella
resurfacing. Clin Orthop 205:166, 1986.
69. Stulberg SD, Slulberg BN, Hamati Y, Tsao
A: Failure mechanisms of metal-backed
patellar components. Clin Orthop 236:88,
1988.
70. Thompson M, Hood RW, Insall JN: Patellar
fractures in total knee arthroplasty.
Orthop Trans 5:490, 1981.
71. Vernace JV, Rothman RH, Booth RE Jr,
Balderston RA: Arthroscopic management
of the patellar clunk syndrome following
posterior stabilized total knee arthroplasty.
J Arthroplasty 4:179, 1989.
72. Wasilewski SA, Frankl U: Fracture of
polyethylene of patellar component in total
knee arthroplasty, diagnosed by arthroscopy.
J Arthroplasty 4(Suppl):S-19, 1989.
73. Wetzner SM Bezreh JS, Scott ED, Bierbaum
BE, Newberg AH: Bone scanning
in the assessment of patellar viability
following knee replacement. Clin Orthop
199:2 15, 1985.
74. Windsor RE, Scuderi GR, Insall JN: Patellar
fractures in total knee arthroplasty. I
Arthroplasty 4(Suppl):S-63, 1989.

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09.45 - 12.15 h
RODILLA / KNEE
MIS y PTR
TKA and MIS
Moderador / Moderator: Carlos Resines
SELECTING THE BEST
APPROACH
P. Bonutti, MD
Effi ngham, Illinois, USA
PURPOSE
MIS TKA has been defi ned primarily based on
the Quadriceps exposure: 1) Mini-Midvastus
(VMO Snip) 2) Modifi ed Median Parapatellar
(“Quad Saving”); 3) Min-Subvastus; 4)
Modifi ed Mini-Subvastus 5) Direct Lateral.
All incorporate the principles of: 1) reduced
incision; 2) quadriceps sparing approach;
3) downsized instrumentation; 4) in situ
bone cuts. To survey the advantages and
disadvantages of each of these approaches
based on the authors experience of over 1500
consecutive MIS TKA.
MATERIALS AND METHODS
We retrospectively evaluated our experience
with the 5 MIS quad approaches to identify
the advantages and disadvantages of each
of these approaches in regards to; 1) Patient
Selection, 2) Deformity Correction, 3) Ease of
Exposure, and 4) Technical Diffi culty.
RESULTS
The Mini-Midvastus (VMO snip) is a straight
forward extensile approach which can be
used on all patients regardless of age, weight
or deformity. The Modifi ed Median Parapatellar
(Quad Saving) is technically demanding
and requires high patient preselection. The
approach requires osteotomy of the patella
fi rst, then the distal femur in a piecemeal fashion.
Instrumentation, especially for patella
and distal femoral cut can be diffi cult and accuracy
of the cuts has been questioned. The
Mini-Subvastus is technically challenging and
is more diffi cult to expose the anterior femur.
It can be quite challenging in well-muscled
males or in patients with patella baja. The
Modifi ed Mini-Subvastus (Muscle Slide) appears
to be a universal approach and allows
excellent exposure to the anterior femur. It
avoids any questions of denervation of the
VMO muscle and is extensile. We have found
this to be very useful in well-muscled patients
and can be universally in all patients. Finally,
the Direct Lateral Approach is the most complex.
It is the most cosmetic approach but
instrumentation requires Computer Navigation
for accuracy. The approach also requires
a special downsized tibial component which
may lead to early loosening and there is a
higher complication rate documented with a
signifi cant learning curve.
CONCLUSION
Overall MIS TKA is a challenging technique
which requires an evolutionary approach.
Mini-Midvastus (VMO snip) can be a universal
approach. The Mini-Subvastus approach
is technically challenging. The Modified
Mini-Subvastus approach requires a learning
curve but can be a universal approach. The
“Quad Saving” requires signifi cant patient
preselection and there are issues of accuracy
of the bone cuts. The Direct Lateral approach
appears to be the most diffi cult and has the
highest potential for complications. Overall,
we recommend an evolutionary approach to

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MIS TKA. The Mini-Midvastus and the Modifi
ed Mini-Subvastus can be techniques which
can be applied to all patients regardless age,
weight, and deformity.
MIS KNEE. A SOFT
TISSUE OPERATION?
H. Delport
Head Departament of Orthopaedics.
AZ Waasland Sint Niklaas, Belgium
The hype of MIS has resulted in the observation
that most surgeons have reduced their
incisions to smaller ones.
Failure in alignment and position of the components
is always visible on x-rays. Other non
visible anatomic structures (nerves,vessels,
ligaments,etc.) are at risk during the procedure
and should be respected.
Damaging the cutaneous nerves of the knee
region can eventually lead to neurinoma
formation. This not only gives raise to numb
areas but occasionally can cause extreme
pain.
Some approaches are infl uencing the innervation
of the vastus medialis. Different
patterns of this nerve can be described.
Saving the supra- and infra-patellar fat pad
has several benefi ts. This is important for
the patellar blood supply, but also has biomechanical
implications.
The medial supporting structures are to be
respected. Care should also be taken to the
postero-latertal corner during the balancing
and releasing action in this area.
Always remember the minimal distance between
the posterior capsule and the popliteal
arterty in extension and fl exion. As shown by
prof.M.Prettenklieber (Vienna) the distance
between the joint capsule and the popliteal
artery is subject to a high degree of variations
and ranges from 2 to 37 mm. It may even
decrease in fl exion !
Our message is :please take care of the
important soft tissues during MIS Total Knee
Replacement.
PITFALLS OF MIS TKA
D. A. Dennis, M.D.
Adjunct Professor, Dept. of Biomedical
Engineering, University of Tennessee
Assistant Clinical Professor, University
of Colorado Health Sciences Center
Clinical Director, Rocky Mountain Musculoskeletal
Research Laboratory
Denver, Colorado, USA
I. TKA Goals
A. Optimize Function & Survivorship
B. Accelerate Recovery
1. As Long As No Compromise In Function
or Survivorship!!
II. MIS TKA Proposed Advantages
A. Quicker Recovery
B. Reduced Length of Stay
C. Reduced Blood Loss
D. Better Early Quad Function
E. Less Discomfort
III. MIS TKA Potential Disadvantages
A. Component Malposition
B. Inferior Ligamentous Balance
C. Inferior Cementation / Fixation
D. Inferior Long Term Results
E. Increased Perioperative Complications
IV. Author’s Hypotheses
A. Quicker Recovery / ↓ Length of Stay
Overstated
B. ↑ Technical Errors & Complications Will
Occur Resulting In Inferior Long-Term
Clinical Results With Technology and
Techniques Currently Utilized
V. Complications I’ve Observed
A. Component Loosening (18 Months
Postop)

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B. Component Malposition
1. 13° Internal Rotation of Femoral Component
2. 82° Knee Flexion
C. Instability
1. Dislocation (MCL Transected)
D. Popliteal Artery Laceration
E. Skin Necrosis / Infection
F. Retained Bone Cement
G. Inferior Tibial Cementation Quality
VI. MIS TKA Future
A. Better / Smaller Instruments
B. Better Cementless Ingrowth Materials
C. Use in Combination with Computer Assisted
Navigation
VII. Summary
A. Technically Well-Done Procedure Is Most
Paramount
B. Focus On The 15 YEAR Rather Than The
15 DAY Clinical Result.
C. Don’t Be Drawn Into Inferior Results Due
To Clever Marketing Schemes
PITFALLS AND
COMPLICATIONS
OF MIS TKA
P. Bonutti, MD
Effi ngham, Illinois, USA
Introduction:
Minimally invasive total knee arthroplasty
has generated tremendous interest as well
as controversy. The authors have utilized a
minimally invasive approach on all knees for
the past fi ve years and this study examined
the complications of the fi rst 1000 of these
knees (817 patients).
Materials and Methods:
The minimally invasive approach has been
utilized in 1,000 knees studied which encompassed
a minimal incision (less than 10
centimeters), quadriceps muscle sparing, and
non-patellar everting techniques for total knee
arthroplasties. This study reviewed all of the
clinical and radiographic complications of this
technique including manipulations, re-operations,
and component revisions.
Results:
Complications included 25 manipulations, 12
arthroscopic procedure for painful patellofemoral
crepitus (mostly an initially non-visualized
retained lateral band), and 8 operative
explorations for various component problems.
There was one impending tibial component
and one impending femoral component
radiographic failure. Most of the operative
complications (60%) occurred in the first
200 cases.
Discussion and Conclusion:
Despite a low complication rate, this study
has yielded insights on potential improvements
in performing total knee replacements
with this minimally invasive technique. The
major concern from this analysis was tibial
component loosening which may be related
to decreased exposure and possibly poor
cement pressurization. Keel length reduction
or modifi cation may lead to improvement in
survival.
MIS IN TKR
D. Griffi n
Warwick Medical School
Coventry, Great Britain

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MINI-INCISION TKR
D. Dalury
John Hopkins Hospital, Baltimore, USA
Smaller incisions are a natural consequence
of surgeon confi dence and experience, instrument
design and patient demands. Several
authors have found no increase in complications
with smaller incisions while others have
documented more problems with alignment
of implants and wound problems when trying
to minimize the skin incision. While the
theoretical advantages of Mini incision TKR
are easier recoveries for patients, surgeons
should never compromise outcomes simply
for a smaller incision. This paper will discuss
the pros and cons of MiTKR.

Notas / Notes
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12.15 - 14.00 h
RODILLA / KNEE
MIS y navegación
MIS and navigation
Moderador / Moderator: Michael Freeman
THE ROLE OF COMPUTER
ASSISTED SURGERIES
D. Dalury
John Hopkins Hospital Baltimore, USA
NAVIGATION AND MIS,
HOW MUCH DOES IT HELP?
W. Fitz
Arthritis Center. Brigham &
Woman’s Hospital, USA
The use of computer guidance for improved
mechanical alignment has been documented
in several studies (1,2). Early reports on minimal
invasive (MIS) total knee replacement
(TKR) document shortened rehabilitation,
less pain and pain medication consumption
and better fl exion early as well as one year
post-operatively (3,4). Although several
studies have shown appropriate component
positioning on x-rays, the use of navigation in
MIS TKR may provide synergism to improve
component positioning and long-term results
without increasing morbidity and mortality
of MIS total knee replacement. However,
despite the promise of surgical navigation
for orthopedic surgery, there are three major
disadvantages for computer navigation in
TKR:
1. During the registration process certain
anatomic landmarks, such as the femoral
epicondyles are diffi cult to register in MIS
TKR. Recently, to improve accuracy of
the epicondylar line a surgeon’s position
medial to the joint was recommended (5).
We feel not comfortable to rely on these
landmarks and recommend the use of a
balancing gap technique as described by
John Insall, using a tensiometer based
on the computer-guided, verifi ed tibial cut
to create an equal fl exion and extension
gap.
2. The placement of Schanz-screws for the
light-refl ecting arrays is not recommended
in the mid shaft of the femur and tibia to
avoid femoral and tibial stress fractures.
We prefer to place the Schanz screws as
close to the proximal tibial and the distal
femoral metaphysis as possible. After removal
of the arrays, the pin-wholes should
be protected by the femoral and tibial
component of the TKR to avoid stress raisers.
The pin placement close to the distal
femoral and proximal tibial cut requires to
extend skin and extend of approach into
the extensor mechanism.

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3. Besides the more technical demands in
MIS TKR the use of navigation extends
the surgical time and complexity of the
case. Current systems do not reduce the
most sensitive process of registration to
a minimum.
Newer technology such as electromagnetic
tracking will be available soon and will
eliminate the placement of the light-refl ecting
arrays by small removable bone screws.
Software improvements will provide different
levels of sophistication and may provide very
simple and user-friendly solutions to reduce
the registration process and total surgical
time.
Patient specifi c knee implant systems derived
from a pre-operative CT scan are introduced
to the market (ConforMISTM). These systems
are placed without traditional surgical instruments
using single-use 3D surgical guidance
molds. The 3D surgical guidance mold is a
negative of the articular surface. It is placed
on the articular surface and includes guidance
for drills and the posterior condylar cut.
Clinical studies will have to demonstrate its
role besides computer assisted surgery.
1. Sparmann M, Wolke B, Czupalla H et al.
Positioning of total knee arthroplasty with
and without navigation support. A prospective,
randomised study. J Bone Joint Surg Br
2003; 85 (6):830-5.
2. Chauhan SK, Clark GW, Lloyd S et al.
Computer-assisted total knee replacement.
A controlled cadaver study using a multiparameter
quantitative CT assessment of
alignment (the Perth CT Protocol). J Bone
Joint Surg Br 2004; 86 (6):818-23.
3. Haas SB, Cook S, Beksac B. Minimally invasive
total knee replacement through a mini
midvastus approach: a comprehensive study.
Clin Orthop Relat Res. 2004;428:68-73.
4. Laskin RS, Beksac B, Phongjunakorn
A, Pittors K, Davis, J, Shim J, Pavlov H,
Petersen M. Minimally Invasive Total Knee
Replacement through a Mini-midvastus Incision:
An Outcome Study. Clin Orthop Relat
Res. 2004;428:74-81.
5. Matziolis G, Krocker D, Tohtz S, Perka C.
Variance of identifi cation of femoral epicondyles
in navigated total knee arthroplasty. Der
Orthopaede, 2006; Vol. 35, 8: 848 - 852.

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13.00 - 14.30 h
RODILLA / KNEE
Complicaciones
Complications
Moderador / Moderator: Leo Whiteside
EVALUATION OF THE
PAINFUL KNEE AFTER TKA
J. Romero, M.D.
Endoclinic Zurich, Center for Arthroplasty
and Joint Surgery,
Klinik Hirslanden, Switzerland
Total knee arthroplasty (TKA) is a most effective
treatment for advanced degenerative
joint disease of the knee. Although satisfactory
results can be expected in most of the
patients, occasionally the outcome may be
compromised by pain and poor range of motion
after uneventful surgery and postoperative
course. Stiffness of the knee is a frustrating
complication for both the patient and the
surgeon. A variety of activities of daily living
and the overall quality of life is compromised
by limited fl exion and incomplete extension.
Stiffness may or may not be accompanied
by pain at rest, but the attempt to forcefully
increase the arc of motion of a stiff knee is
usually painful. Ambulating with a knee that
does not fully extend increases the muscular
work of walking and decreases endurance,
particularly in the quadriceps muscle. Walking
of a level surface is possible if the knee fl exes
only 45° to 55° during swing phase. Ascending
or descending stairs requires about 85°
of fl exion. Standing from a chair is facilitated
if the foot can be brought under the seat; this
usually requires 95° of fl exion. The patients
demands after total knee arthroplasty have
increased over the last years since most of
them enjoy bicycling, mountain hiking, skiing
and other sports activities which require fl exion
well beyond 90°. High fl exion angles are
required by a variety of cultural and religious
habits such as prayer (125°) and squatting
for eating or hygiene (135°). Therefore the
defi nition for stiffness is not absolute and
depends on the patients demand. In practice,
a patient who fl exes less than 100° or lacks
more than 10° for full extension considers
his surgery usually as a failure. If attempts
at non-operative management such as pain
medication, physiotherapy, and perhaps
under certain conditions manipulation under
anesthesia have failed, and the knee remains
with poor range of motion, surgery may be
the only option. If an operative treatment is
considered it is mandatory to evaluate the
underlying condition of the limited arc of motion.
It may have a mechanical or a biological
origin. If the main complaint is pain without
loss of motion, the origin of pain is primarly
mechanical, however psychological factors
may also play a certain role. In any case
evaluation of the painful total knee arthroplasty
consists of a thorough history, as well
as physical and several other invasive and
non-invasive examinations, and laboratory
and imaging testing.
The painful knee without stiffness
It is important to obtain the information from
the patient on when he developed a painful
knee after TKA. If the patient was never
pain-free following surgery, diagnosis such
as instability, prosthetic malpositioning and
malsizing with soft tissue impingement,
lateral patellar facet syndrome or patellar

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dislocation, and popliteus tendon dysfunction
should be considered. If the pain developed
months or years after TKA, loosening,
progressive ligamentous incompetence or
hematogenously based infection. Physical
examination will differentiated between a
painful knee with or without reduced range
or motion. If fl exion is possible up to 90°,
stability assessment in both, extension and
fl exion is mandatory. Laxity measurements
in fl exion may be quantifi ed with stress fl uoroscopy
as described by Stähelin et al.1. It
may reveal a fl exion-extension gap mismatch
or an asymmetrical fl exion gap which is due
to insuffi cient ligament balancing or femoral
component malrotation2. The evaluation of
the position of the femoral component in the
transverse plane – often referred to as the
“rotational” position of the femoral component
– is performed using computer tomography3.
It is important to standardize the level above
the joint line of the computer tomography
image for reliable and reproducible measurement.
Our recent study demonstrates
that the best interobserver correlation was
found using the condylar twist angle (CTA) at
30 mm above the joint line4. The CTA is the
angular measurement subtended by the clinical
transepicondylar axes (TEA) which uses
the most prominent points of the medial and
lateral condyle and the posterior condylar line
(PCL). Excessive femoral internal malrotation
is responsible for lateral fl exion instability and
excessive femoral external malrotation is the
source of popliteus tendonitis. Plain radiographs
in the frontal plane will depict component
overhang which may irritate the joint
capsule and impinge with extraarticular soft
tissue such as the medial collateral ligament
(medial tibial overhang) or the medial patellofemoral
ligament (medial femoral overhang).
Plain radiographs in the sagittal plane are
useful for assessement of tibial component
slope and femoral fl exion-extension position.
Long standing x-rays are useful not only for
evaluation of component malalignment or
entire limb varus-valgus abnormalities but
also to detect distant pathologic conditions
such as tumors, stress fractures or simply
hip joint disease irradiating into the knee.
Detection of patellar problems such as lateral
patellofemoral hyperpression syndrome or
subluxation require patellofemoral axial view
radiographs. If the source of pain is suspected
in the patellofemoral joint assessment not
only of the femoral component rotaion but
also of the rotational position of the tibial tray
is required using transverse CT scans. Early
stages of loosening or failed osteointegration
(cementless TKA) can only be detected using
fl uoroscopically-assisted radiographs which
facilitate radiographic-beam placement perfectly
tangential to the fi xation interface5. Osteolysis
is most commonly detected by plain
radiographs, but may occasionally only be
suspected in technetium scans. Otherwise,
the role of nuclear medicine in evaluation
of painful TKA is unclear since sensitivity is
typically high but specifi ty is variable and in
addition, most scans demonstrate prolonged
increased uptake of the isotope. If the only
hot spot on the scan is on the patella it may
be indicating patellar necrosis or overuse in a
non-resurfaced patella. Magnetic resonance
imaging with metal subtraction software
may provide various diagnosis including
osteolysis, synovitis, bursitis, ligamentous or
tendinous injury, fat-ad scarring, pigmented
villonodular synovitis, and intramuscular
hematoma6. However, MRI is far from being
a diagnostic method of fi rst choice. Ultrasonography
has been reported to have the
ability to determine polyaethylen wear with
an accuracy of 0.5mm7.
Evaluation of the painful stiff knee
Physical examination is very important as
it categorizes the knee painful knee in two
groups: pain with and without reduced arc of
motion. Mechanical factors such as asymmetric
fl exion gap as a consequence of femoral
component malrotation, flexion-extension
gap mismatch, joint line elevation, femoral
component oversizing, patellofemoral joint
overstuffi ng, anterior tibial slope, inadequate
clearance between the posterior condyles of

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the femoral component and the posterior femoral
cortex as a consequence of unremoved
oseophytes or inadequate posterior capping
may be responsible for painful limited motion.
Plain x-rays or CT scans may detect most of
the mechanically related factors.
A painful stiff knee without identifi able mechanical
reason has its origin in a biological
process which induces inflammation and
scarring of the synovium and adjacent
connective tissue such as the collateral
ligaments, the patellar tendon, the fat pad
and ultimately the subcutaneous layer and
the skin. Arthrofi brosis8 of the knee is the
end stage, in the severest case it results in
patella baja9.
Six biological origins of a painful stiff knee
have to be considered if mechanical factors
have been ruled out:
(1) Recurrent hemarthrosis
(2) Infection
(3) Herotopic ossifi cation
(4) Allergy
(5) Complex regional pain syndrome.
Recurrent hemarthrosis is a clinical diagnosis
in the early postoperative periode. Aspiration
is the fi rst diagnostic and therapeutic method
of choice, but if recurrency persist arthrotomy
is occasionally required. Aspiration is also
mandatory if pain and swelling increase in the
early postoperative days, accompanied by
temperature elevation and increase of white
blood count (WBC). Elevation of C-reactive
protein (CRP) is normal in the fi rst 3 postoperative
weeks and is therefore useless in the
early postoperative period.
However, if it does not drop constantly or rises
even further, infection must be suspected. If
WBC and CRP rise after months or years
hematogenous infection is suspected. Satisfactory
diagnosis can only be made if culture
of synovial fl uid reveals a germ. If no germ is
identifi ed, diagnosis may remain uncertain.
Particularly a low-grade infection, where the
postoperative course is unsatisfactory and
the knee remains warm, swollen, painful,
and with reduced arc of motion, is diffi cult to
manage. The knee may not be differentiated
from a condition with has been known by several
terms: algodystrophy, refl ex sympathetic
dystrophy, M. Sudeck, causalgia and others.
Complex regional pain syndrome (CRPS) is a
description created by the IASP (International
Association for the Study of Pain) for an infl
ammatory disease after surgery or trauma
which summarizes these terms. CRPS I is
associated with skin nerve damage during
surgery, and CRPS II is not. Ethiopathology
is not well understood, but in both cases the
sympathetic (autonomous), sensory and motor
nerve system is disturbed. The symptoms
of acute arthrofi brosis as a consequence
of CRPS consist of pain at rest, which can
range between moderate and severe, hyperalgia,
dysaesthesia and skin temperature
dysregulation. The skin of the index knee can
be colder (in 20% of the cases) or warmer
(in 80% of the cases) than the contralateral
knee. Skin color turns into red because of increased
vascularisation, or it can be pale and
cyanotic if skin vascularisation is decreased.
Hyperhydrosis may predominate (50% of the
cases) over hypohydrosis (20% of the cases).
CRPS I may have a less severe course and
patients suffer often only of pain during knee
motion. Attemts do differentiate CRPS from
low-grade infection using modern diagnostic
tools such as positron emission tomography
are frustrating10. Arthroscopy is indicated to
obtain synovium biopsy for tissue culture and
histological examination may occasionally
help to rule out either CRPS or infection.
Heterotopic ossifi cation is easy to detect
on x-rays in the advanced stage, the early
stage may best be evaluated with technetium
scans.
Allergy to orthopedic implants is a controversial
tissue11. Fact is that patients may be
allergic to kalium dichromate, nickel sulfate,
and cobalt chloride, as well to methyl methacrylate
and antibiotics used with bone cement,
all materials used with orthopaedic implants.
There is no evidence so far to support the
hypothesis that these materials induce tissue
reactions that may result in infl ammation and
cell proliferation resulting in swelling, arthro-

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fi brosis, and eventually pain. Observations
however, may suggest some association
between positive epicutaneous exposition
tests with those materials and an unfavorable
postoperative course after TKA.
Bibliography
1. Stähelin T., Kessler O., Pfi rrmann C.W.,
Jacob H.A.C., Romero J.: Fluoroscopically
assisted stress radiography for varus/valgus
stability assessment in fl exion after
TKA. J Arthroplasty 18(4):513-515, Jun
2003
2. Romero J., Stähelin T., Binkert C., Pfi rrmann
C.W., Hodler J., Kessler O.: The
clinical consequences of flexion gap
asymmetry in total knee arthroplasty. J
Arthroplasty, in press
3. Berger R.A., Crossett L.S., Jacobs J.J.
Rubash H.E. Malrotation causing patellofemoral
complications after total knee
arthroplasty. Clin Orthop 356:144-53,
Nov 1998
4. Suter T., Zanetti M., Schmid M., Romero J.:
Reproducibility of measurement of femoral
component rotation after total knee arthroplasty
using computer tomography. J
Arthroplasty 21 (5):744-748, Aug 2006
5. Vyskocil P., Gerber C., Bamert P. Radiolucent
lines and component stability in knee
arthroplasty. Standard versus fl uoroscopically-assisted
radiographs. J Bone Joint
Surg 81-B:24-6, 1999
6. Sofka C.M., Potter H.G., Figgie M., Laskin
R.: Magnetic resonance imaging of total
knee arthroplasty. Clin Orthop 406: 129-
35, 2003
7. Yashar A.A:, Adler R.S:, Grady-Benson
J.C., Matthews L.S:, Freiberg A.A. An
ultrasound method to evaluate polyethylene
wear in total knee replacement
arthroplasty. Am J Orthop 25(10):702-4,
Oct 1996
8. Ries MD, Badalamente M. Arthrofi brosis
after total knee arthrolasty. Clin. Orthop.
380:177-83, 2000
9. Romero J., Borgeat A., Cartier P. Patella
baja. Arthroskopie 12:237-45, 1999
10. Stumpe K.D.M, Romero J., Ziegler O.,
Kamel E.M., von Schulthess G.K., Strobel
K., Hodler J.: The value of FDP-PET in patients
with painful total knee arthroplasty.
Eur J Nucl Med Mol Imaging, in press
11. Thomas P., Summer B., Sander CX.A:,
Przybilla B., Thomas M., Naumann T.
Intolarance of osteosynthesis material:
evidence of dichromate contact allergy
with concomitant oligoclonal T-cell infi ltrate
and TH1-type cytokine expression in the
peri-implantar tissue. Allergy 55(10):969-
72, Oct 2000
EVALUATION AND
TREATMENT OF THE PAINFUL
TKA WITH COMPLEX
REGIONAL PAIN SYNDROME
AND ARTHROFIBROSIS
R. “Dickey” Jones, M.D.
U.T. Southwestern Medical Center,
Dallas, TX, USA
DIAGNOSIS AND
MANAGEMENT OF MIND-
FLEXION INSTABILITY
FOLLOWING TKR
D. Dalury
John Hopkins Hospital Baltimore, USA

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FEMOROTIBIAL
INSTABILITY AFTER TOTAL
KNEE ARTHOPLASTY
J. Romero, M.D.
Endoclinic Zurich, Center for Arthroplasty
and Joint Surgery,
Klinik Hirslanden, Switzerland
After Infection which is the fi rst most common
cause for revision surgery within the fi rst fi ve
years after primary total knee arthroplasty
(TKA) instability is the second most common
cause1. Instability accounts for 20 to 30% of
major revision TKA series in the literature1,2.
Mild to moderate increased varus-valgus
laxity in extension may clinically well be tolerated3.
However, major instability may be an
important cause for total knee arthroplasty
failure4 and has to be looked for. Physical
examination consist of laxity tests in extension
and near 90° of flexion. Particularly
fl exion laxity is not well recognized clinically
and may be reliably tested using stress fl uoroscopy5.
A variety of different circumstances may be
responsible for increased femorotibial laxity
after TKA:
• Asymmetric instability in extension:
Cause: Malalignment of the tibial and
femoral component in the coronal plane
Treatment: Component revision
• Asymmetric instability in fl exion:
Cause: Femoroal component malrotation
Treatment: Femoral component revision
(if modularity of the primary total knee allows
correction of the rotational position of
the femoral component) or revision into a
CCK system
• Asymmetric instability in flexion and
extension:
Cause: Overrelease or damage of ligamentous
structures
Treatment: Revision into Rotating hinge
total knee system
• Symmetric instability in extension:
Cause: Flexion-extension mismatch
Treatment: Revision of femoral component
(if modularity of the primary total knee
allows distal positioning of the femoral
component) or revision into a CCK system
(in order to re-establish correct joint line)
• Flexion-extension mismatch
Treatment: Increase polyethylene thickness
and revision of femoral component (if
modularity of the primary total knee allows
proximal positioning of the femoral component)
or revision into a CCK system (in
order to re-establish correct joint line)
• Symmetric instability in fl exion and extension:
Cause: Polyethylen undersizing
Treatment: Polyethylen revision (increase
thickness)
• Sagittal instability:
Cause: PCL incompetence
Treatement: Revision into ultracongruent
polyethylene or posterior cruciate substituting
knee system
1. Fehring TK, Odum S, Griffi n WL, Mason
JB, Nadaud M: Early Failures in Total Knee
Arthroplasty. Clin Orthop 392:315, 2001
2. Sharkey PF, Hozack WJ, Rothman RH,
Shastri S, Jacoby SM: Why are total knee
arthroplasty failing today. Clin Orthop
404:7, 2002
3. Edwards E, Miller J, Chan KH: The effect
of postoperative collateral ligament laxity
in total knee arthroplasty. Clin Orthop
236:44, 1988
4. Mitts K, Muldon MP, Gladden M, Padgett
DE: Instability after total knee arthroplasty
with the Miller Galante II total knee - 5-7
years follow-up. J Arthroplasty 16:422,
2001 Stähelin T, Kessler O, Pfi rrmann C,
Jacob HAC, Romero J: Fluoroscopically
assisted stress radiography for varus-valgus
assessment in fl exion after total knee
arthroplasty. J Arthroplasty 18:513, 2003

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15.45 - 19.00 h
RODILLA / KNEE
Rodilla de revisión
Revision knee
Moderadores / Moderators: Carlos Rodríguez-Merchán, David Dalury
DE UNI A PTR - TKA
AFTER FAILED UNIS
L. López Durán
Hospital Clínico San Carlos,
Madrid, España
HOW TO REDUCE
WEAR IN TKA?
D. Dalury
John Hopkins Hospital Baltimore, USA
Polyethylene wear is an inevitable aspect of
TKR. Early TKR designs had little osteolysis
and wear. Mid 1980s designs which introduced
modularity had higher rates of wear.
Newer designs addressed shortcomings
such as poorer locking mechanisms, fl at on
fl at designs and improved polyethylene. The
most intriguing “newer” design is the rotating
platform. Rotating platforms decrease wear
by increasing contact area and decreasing
contact stresses.
Wear in TKR can be decreased by appropri-
ate surgical technique, implant design and
patient selection. This paper will discuss
these topics in detail.
BONE RECONSTRUCTION AND
IMPLANT FIXATION IN
REVISION TOTAL KNEE
REPLACEMENT
L. Whiteside
Missouri Bone and Joint Research
Foundation Missouri Bone and Joint Center
St. Louis, Missouri, USA
Reconstitution of bone stock is a primary
concern at revision surgery for failed total
knee arthroplasty. Fixation often is diffi cult
because the cancellous bone has been depleted,
so it is tempting to cement the implant
to diaphyseal cortical bone. However, revision
with cement ultimately destroys more
bone stock. Rather, techniques that use an
uncemented stem to engage the isthmus
and bone graft to fi ll the defects can provide
adequate fi xation as well as the opportunity to
reconstruct the bone stock about the knee.
The major concerns with massive bone grafting—vascularization
and incorporation—remain
signifi cant issues in the knee, and bone
grafting with allograft still raises the question
of immunocompatibility. Bone tissue itself is
not highly immunogenic, but the marrow cells
incite a vigorous immune response and can
create an infl ammatory process that blocks
ossifi cation and incorporation of the graft.

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Early reports of allograft reconstruction in
the tibia and cementless fi xation of the tibial
component have been encouraging, and
reconstruction of the femur with cementless
components has been well documented in the
literature. Loss of bone in the distal femur is
a major problem after a cemented total knee
arthroplasty has failed, and revision surgery
with a cemented stem can cause even more
bone loss. An effort has been made since
1984 to reconstruct bone defects with morselized
allograft bone and to fi x the implants
to the patient’s remaining bone structure
using osteointegration techniques. It was
initially thought that cementless fi xation of the
components would be tenuous and that repeat
revision would be necessary to achieve
durable fixation with the improved bone
stock. However, durability of the construct
has been surprisingly reliable and repeated
revision due to failure of fi xation has not been
necessary.
In cases of infected total knee arthroplasty,
treatment regimens range from debridement
and antibiotics to removal and fusion, but the
standard treatment has been to remove the
implants, treat with antibiotics for six weeks,
and fi nally perform revision arthroplasty with
antibiotic-impregnated cement. However,
cementless reconstruction is attractive for
these revision cases because further bone
destruction is avoided and bone stock also
can be restored.
BONE PREPARATION
Bone loss is one of the major problems in
failed total knee arthroplasty, so minimal bone
should be resected during preparation to preserve
the remaining bone stock. The amount
of bone erosion makes complete seating of
the component nearly impossible, so that
augmented fi xation with a stem almost always
is necessary to achieve toggle control of the
implant. This technique results in substantial,
uncontained defects on both the femoral and
the tibial sides. Seating the implant on the
patient’s own bone stock controls axial migration,
and the stem prevents the implant from
tilting into the defect. Screw and peg fi xation
can add stability to the construct, thereby
allowing the cavitary defi ciencies to be fi lled
with morselized bone. This bone grafting
technique promotes rapid healing and reconstitution
of bone stock without the technical
diffi culty and late collapse associated with
massive allograft replacement.
Femoral preparation
When bone destruction is assessed, the medial
and lateral condyles usually are found to
be at least partially intact. With intramedullary
instrumentation as a guide, the distal surface
of the femur should be resected just enough
to achieve fi rm seating of the femoral component
on one side of the bone. Both sides may
be engaged by the implant in some cases, but
often only one of the two condyles can afford
fi rm seating for the femoral component without
excessive resection of the distal femur.
After all the cuts have been made with the
saw and all the surfaces are prepared, the
femoral component is partially inserted and
the morselized allograft is packed into the
defi cient areas. The implant is then driven
until it is fully seated, then more bone graft
can be packed tightly into the distal and posterior
cavitary defects. Prolonged protection
from weight bearing allows healing of bone
into the cavitary defects for mediolateral and
anteroposterior support of the implant.
Tibial preparation
Reconstruction of massive tibial defects also
relies upon rim support for axial loading and
a stem to stabilize the implant. Screws can
be used effectively in the tibial component to
augment fi xation, with nonstructural allograft
fi lling the central and peripheral defects. Massive
block allografting is feasible for these
defects, but with long-stem and augmented
fi xation, morselized cancellous allografting
can reconstruct the proximal tibial bone with
low failure and complication rates.
The lateral tibial cortex usually is relatively
well preserved, and the fi bular head is almost
always present. The fi bular head can be used

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for proximal seating of the tibial component if
the rest of the tibial architecture is severely
destroyed. In the worst cases, all cancellous
bone is gone, leaving a large cavitary
defect and substantial defi ciency of the tibial
rim. Long-stem fi xation is advisable in these
cases regardless of whether block allografting
or morselized allografting technique is used.
When morselized graft is used, the tibial tray
should seat on the intact portion of the tibial
rim, and the stem should engage the isthmus
of the tibia. As with the femoral component,
the tightly fi t diaphyseal stem maintains stability
and prevents tilting of the component,
so that massive defects may be fi lled with
allograft and protected until healing and bone
formation occur in the grafted area.
GRAFTING TECHNIQUE
Block allografts traditionally have been used
for massive bone defi ciencies, but their complication
rates are high, and the destructive
effects of allograft rejection can limit their
long-term success. Large segments of allograft
also heal slowly, are never replaced by
new bone, and weaken as the ossifi cation and
vascularization front proceeds. In contrast,
morselized allograft has proven structurally
reliable for both small and large defects while
supporting new bone formation. Morsels that
are 1 cm in diameter maintain their integrity
long enough to act as a substrate for new
bone formation. Morsels less than 0.5 to
1 cm in diameter tend to be resorbed while
those larger than 1 cm incorporate slowly, if
ever, and tend to collapse.
Rejection can be a major problem with allograft
because marrow is immunogenic.
However, marrow elements can be thoroughly
removed from morselized allograft to
prevent the infl ammatory response and loss
of graft and to capitalize on the osteoconductive
potential of the allograft. The allograft
acts as scaffolding for new bone growth, and
although it is not osteoinductive, demineralized
bone (mildly osteoinductive) and bone
marrow aspirate (highly osteoinductive) can
be added to the allograft to enhance bone
formation. The surrounding bone structure
supplies most of the osteoinductive activity
because metaphyseal bone has a rich blood
supply and maintains the capacity to heal
even after repeated failed arthroplasty.
Grafting preparation and placement
Fresh-frozen cancellous allograft in morsels
measuring 0.5 to 1 cm in diameter is soaked
for fi ve to ten minutes in normal saline solution
that contains polymyxin 500,000 units,
bacitracin 50,000 units, and cephazolin 1 g
of per liter. The fl uid is removed and 10 cc
of powdered demineralized cancellous bone
is added to each 30 cc of the cancellous
morsels. Bone fragments and diaphyseal
reamings are added to improve the osteoinductive
potential. This mixture is packed
into the bone defects, then the implants are
impacted so as to seat on the remnant of viable
bone while compacting the morselized
bone graft.
MANAGEMENT OF
PERIPROSTHETIC
FRACTURES IN TKA
R. “Dickey” Jones, M.D.
U.T. Southwestern Medical Center,
Dallas, TX, USA

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DEALING WITH SEVERE
FEMORAL BONE LOSS
K. R. Berend MD,
A. V. Lombardi, Jr., MD., FACS
Joint Implant Surgeons, Inc.; the New
Albany Surgical Hospital; New Albany,
Ohio Departments of Orthopedics
and Biomedical Engineering; the
Ohio State University OH, USA
As the population ages and as the longevity
of total knee arthroplasty (TKA) increases,
surgeons are faced with more and more
complex reconstructive scenarios. Managing
femoral bone loss in revision and complex
primary TKA is one of these complex surgical
problems. For many years, the orthopedic
oncology world has dealt with distal femoral
bone loss with the use of modular distal
femoral replacement prostheses. Long-term
concerns over fi xation, stress shielding, and
bearing wear have plagued the successful
tumor surgery. In revision TKA, the available
bone stock, both in terms of quality
and quantity, are signifi cantly affected. This
makes successful fixation the first major
issue. Options for reconstruction of distal
femoral bone loss include allograft-prosthesis
composite constructs and distal femoral
replacements. Each option has its own set
of benefi ts and drawbacks. Fixation options
include the use of cemented stems, porous
coated designs, and now newer compression
loaded devices. Again, each alternative carries
a certain risk versus benefi t that must be
weighed by the surgeon. The current authors
prefer the use of distal femoral replacement
in these complex cases. Our experience with
managing severe distal femoral bone loss in
TKA is reviewed. The use of various fi xation
modalities and newer novel alternatives are
presented.
THE ADVANTAGE
OF CONSTRAINT IN
REVISION SURGERY
K. Steinbrink
Evangelisches Krankenhaus Alsterdof
Hamburg, Germany
THE ROLE OF IMPLANT
CONSTRAINT
K. R. Berend MD,
A. V. Lombardi, Jr., MD., FACS
Joint Implant Surgeons, Inc.; the New
Albany Surgical Hospital; New Albany,
Ohio Departments of Orthopedics
and Biomedical Engineering; the
Ohio State University OH, USA
As the degree of deformity, bone loss,
contracture, ligamentous instability and
osteopenia increases, so does the demand
for prosthetic constraint. The workhorse in
revision TKA is the posterior stabilized constrained
(PSC) design. There is a continuum
of constraint available that ranges from CR, to
a CR lipped device, to an anterior stabilized
device, to a posterior stabilized device, to a
PS “plus” with varus-valgus constraint, to a
PSC, to a rotating hinge. The senior author’s
revision TKA experience includes 985 revision
TKA performed from 1988 through 2005.
A PSC device was used in 540 knees (55%),
cruciate retaining in 49 (5%), posterior stabilized
in 200 (20%), and rotating hinge in 195
(20%). A single PSC design (Maxim; Biomet,

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Inc, Warsaw, IN) was used in 395 patients
(421 TKA) including 271 revision (65%),
reimplantation in 90 (21%), conversion in 11
(3%), complex primary in 47 (11%), and total
femur replacement in 2 (0.5%). Indications
for revision were aseptic loosening in 169
(62%), instability in 45 (17%), arthrofi brosis
in 20 (7%), pain in 13 (5%), periprosthetic
fracture in 11 (4%), malalignment in 6, crepitus
in 3, extensor mechanism dysfunction in
3, and component breakage in 1. Etiology
for complex primary was osteoarthritis in 26
(55%), rheumatoid in 13 (28%), and posttraumatic
in 8 (17%). Follow-up in living patients
averaged 5 years. Knee Society clinical score
improved from 48 to 79, range of motion
improved from 91 degrees to 101 degrees.
Overall survivorship, is 89%. Survivorship
with aseptic revision as the endpoint is 94%.
Revision for sepsis was required in 23 knees
(5%). Of these infections, 9 were recurrent in
the series of 90 reimplantation cases (10%)
and 14 occurred in the 331 knees without
history of infection (4%). Indications for constraint
are reviewed.
THE ROLE OF STEMS
IN REVISION TKA
C. H. Rorabeck, MD
Health Sciences Centre
London - Ontario, Canada
Background:
It is safe to use hybrid fi xation (cementless
stems/cemented articular components) when
performing revision TKA with a varus/valgus
constrained device.
Methods:
110 revision total knee replacements were
performed in 107 patients in a single centre
prospective study using revision intramedullary
stems and a highly constrained polyethylene
insert between 1193 and 1999. All
patients received cemented metaphyseal
components and either a cemented or uncemented
revision intramedullary stem. Seventy
of these patients received uncemented
stems in both the femur and the tibia and
were considered as having “hybrid fi xation”
and were the focus of our study. All 70 of
these patients had complete clinical and
radiographic evaluation.
Results:
There were 9 (12.9%) re-revisions: 3 (4.3%
for aseptic loosening, 2 (2.9%) for recurrent
infection and 4 (5.7%) for instability. The 61
remaining patients were followed for a mean
of 5.1 years (range 2 to 10 years). There was
a 4.3% rate of aseptic loosening and Kaplan-
Meier survivorship of 86.9% at 6.3 years for
all revisions. Signifi cant improvements in
pain scores (18 to 42, p

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DIAGNOSIS AND
MANAGEMENT OF
INFECTED TKA
R. “Dickey” Jones, M.D.
U.T. Southwestern Medical Center,
Dallas, TX, USA
Safeguards to diminish infection in TKA
include prophylactic antibiotics, personnel
isolation devices, atraumatic surgical
techniques, antibiotic impregnated PMMA,
and limitation of operating room traffi c and
obtaining primary wound healing. If infection
is suspected, identifi cation or organism and
sensitivity is paramount.
Acute infections (< 3 week history) require
debridement, total synovectomy, retention
of the implant, but change of poly, and 6
weeks parenteral antibiotic. Arthroscopic
synovectomy is unreliable.
In chronic infections (> 3 week history) the
host healing capacity (Cierny classifi cation)
is key to wound healing. Smoking cessation
and supplemental nutrition can improve healing
response.
Surgical goals include debridement of all
necrotic tissue, elimination of the dead
space, and conversion to a “live wound”. The
standard of care is a two-stage procedure,
incorporating an implant moving surface with
a cement-antibiotic composite and beads to
establish and maintain length, tissue compliance
and motion. The femoral component is
removed, brushed, fl ashed, and reused with
new tibial poly. The cement-antibiotic-implant
composite is formed to a “custom implant”
molded to the defects. Organism specifi c
antibiotic can be mixed with CaSO4 bead
making kit to eliminate dead space and deliver
high elution, resorbing over 3-4 weeks.
24cc’s of antibiotic powder per 40gm pack of
cement powder is used for “custom mold” and
no drains are used. Patients are encouraged
to ambulate as tolerated and establish ROM.
Parenteral antibiotics are given for 6 weeks
and response followed with CRP.
Plan second stage reconstruction at 3
months. Infected implants require signifi cant
ancillary support.
PTR SÉPTICA
Dr. X. Flores Sánchez*, Dr. C. Pigrau
Serrallach***, Dr. E. Guerra Farfan*,
Dra. M. del Mar Villar Casares**, Dra.
M. Dolores Rodríguez Pardo***
*Servicio de Traumatología y Cirugía
Ortopédica, **Servicio de Medicina
Interna, ***Servicio de Medicina Interna,
Enfermedades Infecciosas.
La infección periprotésica, origen de padecimientos
no esperados por el paciente informado,
confi ado en sus excelentes resultados
en el 95% de las ocasiones, constituye una
complicación origen de sufrimiento para él y
su entorno, y es motivo de nuevas intervenciones
y estancias hospitalarias, causa de
una morbilidad y mortalidad (aumentadas)
y en defi nitiva de un elevado coste físico,
moral y económico.
La universalización del procedimiento de
sustitución articular y de su futura revisión, el
envejecimiento de la población, la creciente
longevidad y, porque no decirlo, de “los planes
de choque”, hacen que su presentación sea
cada vez más frecuente, es previsible una
duplicación del numero de casos en menos
de una década y su triplicación en quince
años, a pesar del reducido índice de infección
en dichos procesos debidos a las técnicas
actuales de prevención y profi laxis.
Desde Agosto de 1.972 hasta Septiembre del
2.002 en la Unidad de Patología Séptica del

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Aparato Locomotor (U.P.S.A.L.) del Hospital
Universitario Vall d’Hebron, hemos tenido
ocasión de tratar 87 casos de infecciones
periarticulares en los que estaba implicada
la Prótesis Total de Rodilla (P.T.R.).
Para tratar con éxito cualquier proceso séptico,
es muy importante la identifi cación del
germen responsable del problema, ello permitirá
la obtención de los perfi les de sensibilidad
del mismo frente a distintos antibióticos,
haciendo posible la selección del fármaco y
el cálculo de su dosifi cación para obtener a
nivel del tejido óseo una concentración entre
8 y 10 veces superior a su concentración
mínima inhibitoria (C.M.I.).
Por descontado durante la investigación
microbiológica deben considerarse los
gérmenes de crecimiento anaerobio, relativamente
frecuentes en las formas de
presentación crónica, y los responsables de
procesos granulomatosos que precisarán
de una metodología específica para su
aislamiento.
Si bien el germen implicado puede ser identifi
cado en los hemocultivos obtenidos durante
la bacteriemia producida en el transcurso de
una infección periprotésica aguda (precoz o
hematógena), lo más habitual y asequible
es que el germen se identifi que mediante
cultivos obtenidos de material aspirado
en una artrocentesis. La rentabilidad del
método oscila ampliamente, desde un 45%
de identifi caciones publicado por BF Morrey
y el 88% descrito por JN Insall. El valor
predictivo positivo es del 72% y el valor
predictivo negativo de 94% según autores
como J. Levitsky.
Los cultivos negativos en procesos asociados
a infecciones peri protésicas claras desde
el punto de vista clínico presentan distinta
incidencia según diversos autores, hasta del
11%. En nuestra casuística la artrocentesis
no permitió aislar el germen responsable
en un 4’55% de los casos, a pesar de que
dichos casos cumplían ampliamente los
criterios de infección periarticular.
Como decíamos anteriormente, el aislamiento
del germen es de vital importancia
para instaurar un correcto tratamiento
medico y es por ello que la investigación
del germen responsable es imperativa. En
nuestra U.P.S.A.L., buscamos el germen
responsable a nivel de la interfi cie prótesishueso
(en las no cementadas) y de la interfi
cie cemento-hueso (en las cementadas),
fundamentalmente en las formas crónicas
de presentación por considerar que estamos
tratando una osteítis crónica localizada en
el lecho óseo de implantación, en defi nitiva
una osteítis crónica tipo IV de Cierny-Mader.
Para ello procedemos en quirófano, bajo
anestesia y guiados por amplificador de
imágenes, a la obtención de muestras para
estudio microbiológico y anatomopatológico,
mediante trefi nas y pinzas de biopsia. La utilización
de dicha sistemática puede explicar
el bajo índice de cultivos negativos.
La falta de sistemática es origen de falsos
negativos y los negativos reales deben
documentarse si se presentan asociados
a clínicas sugestivas de infección peri-protésica.
Exponemos varios ejemplos de lo que
estamos diciendo.
En nuestra casuística los gérmenes más
frecuentemente aislado son los gram positivos,
en un 54’55%, los gram negativos en
un 31’82% de los casos, polimicrobianas
en el 6’82%, etiquetados como otros en
un 2’27% y en el 4’55% fueron los cultivos
negativos. Comparativamente con otras
casuísticas publicadas, en la nuestra existe
una menor incidencia de gram positivos,
que generalmente son cercanas al 75%, a
expensas de los gram negativos y de las
infrecuentes formas polimicrobianas. La
explicación reside en que al ser nuestra unidad
centro de referencia de esta patología,
tratamos casos que ya han sido objeto de
tratamiento quirúrgico con anterioridad en
los centros emisores, siendo frecuentes en

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dichos pacientes las formas polimicrobianas
y los gérmenes multiresistentes. Estamos
convencidos de que nuestra muestra es un
tanto “especial”.
El tratamiento de las 87 infecciones peri
protésicas en artroplastias totales de rodilla
hasta Septiembre del 2002 origino 128 opciones
terapéuticas distintas, cuyo desglose
detallamos en la imagen adjunta, en ella es
evidente el aumento de la prevalencia de dicha
patología en los años sucesivos y que las
principales opciones terapéuticas escogidas
fueron el recambio en dos tiempos y técnicas
de salvación como la artrodesis femorotibial.
Todo ello lo relacionamos como hemos dicho
anteriormente con que se trata de pacientes
multioperados y cronifi cados. Ello es debido
a que, si bien cualquier especialista en
cirugía ortopédica puede realizar cualquiera
de las técnicas quirúrgicas precisas en el
tratamiento de esta patología, no todos ellos
cuentan en sus centros hospitalarios con el
soporte e infraestructura necesarios para
el correcto tratamiento de estos pacientes.
También es evidente que la baja incidencia
de esta complicación en la mayoría de hospitales
origina una limitada experiencia y largas
curvas de aprendizaje. La dispersión y falta
de homogenización de métodos también
contribuye a la irregularidad de resultados.
Los objetivos a alcanzar en el tratamiento de
las infecciones peri protésicas son: erradicar
la infección, eliminar el dolor y conservar la
función de la articulación.
Cuando la articulación afectada es la rodilla
las opciones terapéuticas son: supresión
antibiótica, desbridamiento conservando los
implantes, recambio protésico en un tiempo,
recambio protésico en dos tiempos, artroplastia
de resección, artrodesis femorotibial
y amputación.
La elección de la opción más adecuada
debe basarse en la existencia de múltiples
variables, el germen aislado es una de ellas,
las demás son: localización de la infección,
tiempo transcurrido desde su instauración,
participación y compromiso de las partes
blandas yuxtaarticulares, grado de estabilidad
de los implantes en referencia a su
fi jación al esqueleto, enfermedades asociadas,
capacidad física del paciente, expectativas
de curación, capacidad técnica del
cirujano y centro hospitalario donde tendrá
objeto el tratamiento.
La difi cultad en mantener los implantes y los
fracasos están íntimamente relacionados con
características intrínsecas de los distintos
gérmenes que no eran tenidas en cuenta
hasta hace unos pocos años. Estas características
están perfectamente defi nidas en
los trabajos de Gristina, Faden y Gordon, en
ellos se describe la denominada “carrera por
la superfi cie”, la existencia de receptores específi
cos en los tejidos y materiales para los
distintos gérmenes, todo ello se resume en la
denominada “colonización del implante” y la
formación de biopelículas, que difi cultarán o
incluso anularán la acción de los antibióticos
y de los sistemas de defensa humorales y
celulares del individuo.
En estudios de osteomielitis experimental se
demuestra la necesidad de un inóculo menor
para desarrollar una infección si está presente
un implante, la existencia de implantes
y fundamentalmente de polimetilmetacrilato
origina una menor capacidad de fagocitosis
de los leucocitos polimorfonuclerares, la
utilización de cepas mutantes de staphylococcus
plasmocoagulasa negativos sin
capacidad de formación de glicocálix, facilita
el tratamiento de las infecciones originadas
por dicho germen.
“La colonización del implante” se produce en
tres fases, en una primera denominada de
“adherencia” están implicados los mecanismos
de adherencia especifi ca bacteria-sustrato
y receptores de superfi cie anteriormente
nombrados. Conseguida la adhesión se produce
la segunda fase denominada de “proliferación-acumulación”
en la cual los distintos
gérmenes proliferan y permanecen unidos
entre si gracias a la producción de un poli-

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sacárido adhesivo intercelular denominado
slime o glicocálix, la rapidez en su formación
depende de cada tipo de germen. Por último
se produce la fase de “perpetuación del biofi
lm”. En dicha fase los gérmenes contenidos
en las capas más profundas del biofilm,
alejados de los elementos nutrientes y en
situación de una anaerobiosis relativa inician
un dialogo entre ellas a través de mediadores
químicos, el denominado “quorum sensing”,
los gérmenes experimentan profundos cambios
que afectan su agresividad, capacidad
de formación de exotoxínas y su perfi l de
resistencia a los antibióticos. Las formaciones
de bacterias-biofi lm, inicialmente sesíles
adoptan formas pediculadas que responden
a las leyes de la hidrodinámica, fragmentos
de estas formaciones pueden liberarse formando
nuevas colonias a distancia.
En nuestra practica diaria tomamos contacto,
aislamos y tratamos las formas planctónicas
del germen siguiendo los antiguos postulados
de R. Koch, permaneciendo las bacterias mutantes
en el seno de las biopelículas desde
donde periódicamente van liberando nuevos
gérmenes constituyéndose en “recidivas”.
En la actualidad la investigación se dirige hacia
la obtención de fármacos que destruyan el
biofi lm, anulen la capacidad de su formación
desde las propias bacterias, impidiendo o
alterando el “quorum sensing”. En este sentido
la asociación de ultrasonidos locales al
tratamiento con antibióticos muestra cierta
efectividad al romper las biopelículas y liberar
los gérmenes.
Estas particularidades que muestran los
gérmenes hacen de la clasifi cación de la
infección periprotésica de Tsukayama la más
adecuada para afrontar el tratamiento de esta
patología, eminentemente quirúrgica en la
actualidad. Tal como han publicado el propio
Tsukayama y autores como Crockarell, el éxito
de la opción terapéutica de desbridamiento
manteniendo los implantes está directamente
relacionada con la precocidad con que se
aplica, ello se relaciona con la formación de
biopelículas y su perpetuación.
Es evidente que la virulencia con que se presentan
determinadas infecciones precoces
depende de la patogeneidad del propio germen,
en este sentido la presentación aguda
de las formas precoces y de algunas agudas
hematógenas se debe a características propias
del germen, así seria el caso cuando
el germen implicado es el Staphylococcus
aureus, Pseudomonas aeruginosa, bacterias
gram negativas y determinadas especies de
Staphylococcus plasmocoagulasa negativos
como podría ser el Staphylococcus saprophyticus
y el Staphylococcus lugdunensis.
En otras ocasiones la infección de la herida
quirúrgica por Staphylococcus aureus se
manifi esta como una evolución tórpida de la
herida operatoria, nuestra actuación debe ser
precoz para impedir la progresión e instauración
del proceso séptico. En la revisión de los
casos que posteriormente se manifestarán
como una infección periprotésica crónica, se
leen con frecuencia frases como:” discreta
febrícula”, “discretos signos infl amatorios de
la herida”, “pequeña dehiscencia de la herida
operatoria”, “discreto hematoma”, “granuloma
herida quirúrgica”, frases todas ellas
premonitorias de lo que sucederá. La actitud
ante tales situaciones debe ser agresiva.
Una vez cronifi cado el proceso, más allá de
un mes de instaurada la infección, la única
acción valida es el recambio completo de los
implantes en los que ya se han perpetuado
los biofi lms (por el momento). El recambio
de implantes puede efectuarse en uno o dos
tiempos, cada uno de los métodos tienen
sus ventajas e inconvenientes. Como ya
hemos citado previamente, en U.P.S.A.L. el
recambio en dos tiempos es el método de
elección posiblemente por las características
intrínsecas de los casos tratados.
El recambio en un tiempo estaría indicado
en pacientes que reúnen una serie de características:
Pacientes tipo A desde la vertiente
fi siológica de la clasifi cación de Cierny-Mader
a nivel sistémico y local, no en infecciones
asociadas a signos de sepsis generalizada,

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existencia de una buena reserva ósea,
germen conocido y de fácil tratamiento antibiótico
con fármacos poco tóxicos, que el
antibiótico de elección posea unas características
físicas, químicas y farmacológicas que
permitan su inclusión en el cemento acrílico
utilizado en la implantación de los componentes.
Estas condiciones sólo se presentan en
un 10% de los pacientes. La existencia de
fístulas, contraindicación para algunos del
recambio en un tiempo, no es para nosotros
motivo de exclusión por tratarse simplemente
de un signo de cronicidad.
El recambio en dos tiempos es la opción
de elección en pacientes tipo A y B de la
clasifi cación de Cierny–Mader, cuando el
germen no ha sido identifi cado o se trata de
gérmenes multiresistentes, en las formas
de presentación crónicas, en las graves
perdidas de estructura ósea, cuando los
antibióticos necesarios presenten elevada
toxicidad o no puedan ser utilizados por sus
características mezclado con el cemento
acrílico necesario en el recambio en un
tiempo y en el fracaso del recambio en un
tiempo. Estas condiciones están presentes
en el 90% de nuestros casos.
En la mayoría de los casos la perdida ósea
estructural es importante, asociándose a
graves inestabilidades, debido a que se trata
de casos muy evolucionados, multioperados
y que han precisado de amplios gestos de
desbridamiento óseo y de partes blandas,
ello origina la necesidad de emplear en el
segundo tiempo durante la reconstrucción
implantes más constreñidos, de apoyo diafisario,
en muchos casos personalizados, las
graves perdidas óseas deben ser reemplazadas
por el implante o mediante injertos óseos
fragmentados o estructurales obtenidos de
banco, no pensamos que el cemento sea
una buena opción para sustituir al hueso y
menos en casos con antecedentes sépticos,
limitamos al máximo su utilización, reduciéndola
a la imprescindible para conseguir la
adaptación del implante a las superfi cies
epifi sarias reconstruidas.
Estamos convencidos de que la utilización
del cemento acrílico en la revisión de estas
artroplastias no es la mejor solución por una
serie de hechos:
• Evidencia publicada, la mayor supervivencia
a largo plazo de aquellos procedimientos
de revisión efectuados con
implantes no cementados.
• Malas condiciones de cementación en las
revisiones por la precariedad del hueso
receptor, con cavidades endomedulares
de superfi cie completamente lisa, nada
parecida a la irregular superficie de
implantación disponible en las cementaciones
de prótesis primarias.
• Malas condiciones de cementación por
la frecuente asociación a falsas vías,
fenestraciones y ventanas óseas, fracturas
metafi sarias e irregularidades en el
lecho de implantación. La utilización de
cemento hace imposible la reparación
ósea espontánea.
• La evidencia publicada por varios autores
como W. Petty, demuestra que el
cemento acrílico posee capacidad de
inhibición de la fagocitosis a nivel de los
leucocitos polimorfonucleares.
• Múltiples artículos publicados informan
de cortos periodos de liberación de antibióticos
desde el cemento. Solo un 20%
del antibiótico contenido en el cemento
se libera.
• En pocas semanas la liberación de antibiótico
desde el cemento se produce
a dosis subterapeuticas, pudiendo favorecer
la aparición de resistencias, en
este sentido la utilización de antibióticos
como la Vancomicina mezclados con el
cemento en protetización primaria, como
profi laxis (registro sueco) nos parece
descabellada y punible.
• Por último, si decidimos la reprotetización
es que consideramos el proceso séptico
solucionado, ¿Por qué los antibióticos?
El trabajo sobre infección experimental de
B. Thornes apoya nuestra falta de confi anza

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en el cemento para la reprotetización de este
tipo de pacientes. El autor infecta a dos grupos
de 22 de animales de experimentación
con una cepa cuyo perfi l de sensibilidad es
conocida de Staphylococcus epidermidis,
a uno de los grupos de 22 animales le ha
sido implantado previamente un fragmento
de cemento acrílico y al otro grupo cemento
acrílico con gentamicina.
Como es evidente la infección se desarrolla
en menor número entre los portadores de
cemento con antibióticos, en 9 casos entre
22, un 41%, mientras que en el grupo portador
de simple cemento se infecta un 73%,
16 de 22.
El autor observa no obstante la aparición de
cepas resistentes a gentamicina, en distinta
proporción en ambos grupo, en el grupo de
solo cemento solo 3 de los 16 infectados
desarrollaron la aparición de resistencias,
el 19%; sin embargo en los casos en que
la gentamicina se incorporo al cemento y
se manifestó la infección, 9 casos en total,
en 7 de ellos el germen era resistente a la
gentamicina, el 78%.
Con una p

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(2002) Development Of Resistant Strains
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THE ONE-STAGE PROCEDURE
IN SEPTIC REVISION 30
YEAR OF EXPERIENCE
K. Steinbrink
Evangelisches Krankenhaus Alsterdof
Hamburg, Germany

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