SMW Supplementum 193 - Swiss Medical Weekly

33 S SWiSS Med Wkly 2012;142(Suppl 193) · www.smw.ch Free communications
FM129
A simple radiographic method to predict femoral
component rotation in gap balancing total knee
arthroplasty – moving towards a concept of individual
femoral component rotation
Fabian von Knoch1 , Christian Ilmer1 , Laurent Harder1 ,
Florian Naal1 , Marius von Knoch2 , Stefan Preiss1 1Schulthess Klinik; 2Klinikum Bremerhaven, Klinik für Orthopädie
& Endoprothetik
Introduction: The femoral component in total knee arthroplasty (TKA)
is believed to be in 3° external rotation (ER) to the transepicondylar
axis (TEA) to improve flexion gap balancing and patellofemoral
tracking. This concept is based on a knee flexion axis that is parallel
to the TEA and a proximal tibia with 3° varus inclination. However
osseous knee anatomy in flexion shows great inter-individual
variability. We hypothesized that femoral component rotation in tibia
first gap balancing TKA is highly variable and can be predicted based
on preoperative knee anatomy in flexion.
Methods: We assessed a consecutive series of 50 PCL-sacrificing
ultracongruent primary TKA. Gap balancing technique was applied
with initial perpendicular tibia cut and femoral component rotation
being determined by ligament tension. Anteroposterior full leg and
axial knee radiographs according to Kanekasu were obtained before
TKA to assess knee anatomy in flexion defined by frontal inclination
of proximal tibia and condylar twist angle (CTA) of distal femur, as well
as after TKA to measure frontal tibial component alignment, femoral
component rotation, and flexion gap symmetry. Patellar tracking was
assessed radiographically before and after TKA. Assuming rectangular
flexion gap and neutral frontal alignment of the tibial component,
femoral component rotation was predicted based on preoperative
frontal tibial inclination and CTA. Linear correlation coefficients of
predicted and actual femoral component rotation were calculated.
Results: Preoperative osseous flexion gap anatomy varied greatly.
Mean proximal tibial inclination was 2.0 ± 2.5° varus (range 6° varus
– 6° valgus) and mean preoperative CTA was 6.3 ± 1.9° internal
rotation (IR) (range 2–10). Measurements of predicted & actual femoral
component rotation strongly correlated (r = 0.77), particularly after
correction for frontal tibial component alignment and flexion gap
asymmetry (r = 0.90). No patella lateralisation was noted in any cases
despite high variation of femoral component rotation (range 12°IR –
2°ER).
Conclusion: We presented a simple radiographic method that allows
prediction of femoral component rotation in gap balancing TKA based
on preoperative osseous knee anatomy in flexion. Our technique
provides additional guidance for component alignment in gap
balancing TKA and may prove useful to evaluate femoral component
rotation after TKA. This study supports the concept of individual
femoral component rotation in TKA.
FM130
Easier recovery following fixed-bearing total knee
arthroplasty: an ambulatory gait analysis of fixedand
mobile-bearing knees through a double-blind
randomized controlled clinical trial
Arthur Grzesiak1 , Antoine Eudier1 , Hooman Dejnabadi2 ,
Kamiar Aminian2 , Estelle Martin1 , Brigitte M Jolles1 1Centre Hospitalier Universitaire Vaudois; 2Ecole Polytechnique
Fédérale de Lausanne
Introduction: The goal of this study was to assess total knee
arthroplasty (TKA) recovery outcome between adult patients with
fixed- and mobile-bearing during the first postoperative year, and at
5 years follow-up, providing gait parameters in real life conditions
as a new objective method.
Methods: This randomised controlled double-blinded study included
56 patients with mobile- and fixed-bearing of the same design who
were evaluated pre- and post-operatively at 6 weeks, 3 months,
6 months 1 year and 5 years. Each participant completed an EQ-5D
questionnaire, and a WOMAC and Knee Society Score were
calculated. Objective gait analysis was also carried out with patients
walking 30 metres on a flat surface with an ambulatory gait-recording
system.
Results: There was no statistically significant difference between
age-matched groups at baseline, on any subjective, semi-objective
or objective parameter. The results of the traditional scoring systems
(EQ-5D, VAS pain, KSS) did not show any clinically meaningful
differences between the groups. There was no significant difference
between groups at any time in objective gait parameters when the
whole population was considered. A secondary analysis after
separating the population according to their age (less than 71 years
old, versus more than or equal to 71 years old) shows that the bearing
type can lead to opposite results in different age groups. Most of the
recorded gait parameters show better results for mobile bearing in
younger patients, while better gait performances were found
systematically in older patients with fixed-bearing TKA at five years
follow-up.
Conclusion: To our knowledge, this is the first study where the gait
performance of fixed- and mobile-bearing of otherwise similarly
designed posterior-stabilized knee replacements have been compared
in real-life conditions. Our results suggest that older patients might not
benefit from a mobile bearing TKA and that extended age controlled
study should be performed to identify an age, above which fixed
bearing should not be the recommended choice.
FM131
5 Year Follow-up: 100 Conventional Non-navigated
Versus 100 Computer-assisted Navigated Total Knee
Arthroplasties – A Prospective Randomized Trial
Johannes Cip1 , Mark Widemschek1 , Eckart Mayr2 ,
Thomas Benesch3 , Archibald von Strempel1 , Arno Martin1 1Academic Teaching Hospital Feldkirch/Department of Orthopedic
Surgery; 2Medical University Innsbruck/Department of Orthopedic
Surgery; 3Medical University of Vienna/Center For Medical Statistics
and Informatics
Introduction: The aim of introducing computer-assisted navigation
systems for total knee arthroplasty was to improve implantation
accuracy and ligament balancing of TKA. However beside many
contradictory publications after short term there is no mid-term data
published comparing computer-assisted surgery with the conventional
TKA technique.
Materials and Methods: In a prospective randomized trial with a
minimum follow-up of 5 years we enrolled 200 patients (200 TKA),
100 TKA performed with the conventional technique (Group A), 100
TKA performed with a computer-assisted navigation system (Group B).
We wanted to show if there is a positive effect of the navigation system
towards TKA survival, radiological component alignment and clinical
outcome. Radiological investigations were performed by standard
X-rays including long leg weight-bearing X-ray measuring the
mechanical axis of the limb, medial proximal tibial angle (MPTA), tibial
slope, patella alpha angle and lateral distal femoral angle (LDFA). For
clinical investigations we determined range of motion (ROM), stability
in full extension and 30° flexion, anterior drawer test, subjective feeling
of instability, anterior knee pain, effusion, Insall Knee Score, Hospital
of Special Surgery Knee Score (HSS) and Western Ontario Mac
Master University Index Score (WOMAC).
Results: No significant difference was found towards TKA survival
or aseptic loosening (Group A 95.4% versus Group B 98.9% 5-year
survival rate, p = 0.368). In Group B we found a significant better
mechanical axis of the limb (1.67° ± 1.6° versus 2.44° ± 2.2° in Group
A; p = 0.015). 81% of Group A versus 90% of Group B were within 3°
varus/valgus deformity of the mechanical axis of the limb (p = 0.157).
Accuracy of tibial slope in sagittal plane was higher in Group B
(p = 0.001). More patients of Group B (95% versus 79% in Group A)
were within a deviation of 4° – 10° tibial slope (p = 0.007). Except
mean deviation of 90° LDFA (p = 0.034) alignment in frontal plane and
patella alpha angle showed no significant difference (p ≥ 0.253).
Clinical examination was similar in both groups (p ≥0.058). Insall Knee
Score total and HSS Knee Score total were higher with the navigated
procedure (p ≤0.026).
Conclusion: Summarized accuracy of mechanical axis of the
limb and alignment in sagittal plane was better with the navigated
procedure. However there was no difference of TKA survival or clinical
performance 5 years after implantation.
FM132
Systematic follow-up of total knee arthroplasty helps
to detect silent massive osteolysis
Lukas Kraler, Daniel De Menezes, Hans-Peter Sieber
Spitalzentrum Biel AG
Introduction: The aim of this study was to examine occurrence of
implant related complications after primary TKA with Wallaby I implant
and ultracongruent insert.
Methods: This retrospective case series includes all primary TKAs
with a Wallaby I implant using an ultracongruent polyethylene insert
(Centerpulse, CH-Münsingen) performed between 1998 and 2004.
Inclusion criteria were primary TKA and minimal follow-up of 6 years.
Post infection cases were excluded. 561 cases met the inclusion
criteria. Patients’ age at surgery was mean 69 y (32–90 y). Patients
were routinely followed-up at 6 w and 3 mt. Thereafter, patients turned
up for regular control at 1 y, 5 y or randomly, when having recurrent
effusion or instability. For the purpose of this study, we invited patients
to a clinical and radiological follow-up in 2010/2011 (6–13 y follow-up).
We also collected data of all patients from archive records. We were
unable to trace 167 cases for a minimal follow-up of 6 y; 72 patients
had died and 37 refused follow-up as they were satisfied with the
result or had difficulties in coming to the hospital. A total of 285 knees
were followed-up to a minimal of 6 y or until revision TKA.
Results: 171 knees did not show any sign of clinical or radiological
failure (mean follow-up 8.2 y). In 97 cases revision was performed