cadera / hip - Active Congress.......

MIÉRCOLES / WEDNESDAY
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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.