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Is patellofemoral osteoarthritis a problem for unicompartmental knee arthroplasty?
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full leg length views, and an axial view in 30
degrees of knee flexion. Overall mechanical
axis, patellar tracking, and progression of
degenerative disease in the patellofemoral
compartment were recorded. We used the clas
sification of Iwano to measure patellofemoral
OA [18]. Data were collected and analyzed
retrospectively to assess the results of UKA
combined with partial lateral patellar face
tectomy for treatment of unicompartmental and
patellofemoral degenerative disease.
Statistical Analysis
Pre-operative and post-operative IKS scores,
range of motion were compared using
wilcoxon’s test. Statistical significance was
defined as p<0.05.
Results
The eleven patients were followed clinically
and radiographically for a mean of 60.3 months
(range: 39 to 91 months). No implant revision
was required during the follow-up period.
Functional Results
10 patients (90%) were satisfied with their knee
function at final follow-up. The mean IKS knee
score improved from 64.9 points (range: 44 to
81 points) pre-operatively to 87.5 points (range:
60 to 100 points) at final follow-up (p= 0.01).
The mean IKS functional score improved from
65.9 points (range: 15 to 100 points) pre-
operatively to a mean of 83.2 points (range: 40
to 100 points) at final follow-up (p= 0.0117).
The mean maximum knee flexion was
136 degrees (range 115 to 150 degrees) pre
operatively and 134 degrees (range 120 to
140 degrees) at final follow-up (no statistic
difference). The mean extension deficit was
0 degrees (range, 0 to 0 degrees) preoperative
and 0.45 degrees (range 0 to 5 degrees) at final
follow-up (no statistic difference). The mean
Kujala score was 84.3 points (range 63 to
100 points) postoperatively. 4 patients had
moderate crepitus.
Radiographic Results
No visible loosening or significant polyethylene
wear occurred. On standing full length plain
radiographs, the mean alignment was 5.5 de
grees of valgus (range: 0 to 12 degrees of valgus)
preoperatively and 3.4 degrees of valgus.
Progression of patellofemoral arthritis was
observed in 2 cases: one level 1 (3 years
follow-up) and one level 2 (7 years follow-up)
of the classification of Iwano (fig. 1, 2).
Fig. 1: Postoperative patellofemoral OA grade 2 (7 years follow-up).