297 / 324
significant differences were found in the preo-
perative and postoperative axial alignment and
in the number of radiolucent lines, between
groups. Regarding the sizes used (Table 5 and
6) there is also a clear difference between the
2 groups, this difference is significant (p<0.001
with the chi square test after regrouping femo-
ral size 0 with size 1 and femoral size 3 with
size 4, and tibial size 1 with size 2 and tibial
size 4 with size 5). The size of the femoral or
tibial implant used was significantly related
to patients height (p<0.001) (Table 7).
Radiolucent lines were most frequently on the
tibial side, but were considered stable and non
evolutional in all cases (Table 4). None of these
patients underwent reoperation. 1 patient in
each group had opposite compartment degene-
rative changes noted at final follow-up. So far,
none of these patients have needed revision. In
the male group, one patient had a conversion to
TKA for pain, and three patients underwent
reoperation without changing the implant. In
the female group, no implants were revised,
and two patients required a reoperation (fig. 1).
Kaplan-Meier analysis revealed a 5-year survi-
val rate of 93.46% (84.8; 100) for men and
100% for women (fig. 1). The difference is
non-significant (p=0.28 - log-rank test). At the
last follow-up, one patient has died in the male
group and two in the female group.
DISCUSSION
Data from the main registries, and large meta
analysis, show that among patients undergoing
TKA, the ratio of women is now consistently
around 60% (Table 8), declining over time
from 70% in 1975 to 61% in the recent 2008
Swedish registry. The higher percentage of
women can be explained [9] by their longer
life expectancy, the higher incidence of osteo-
porosis, osteoarthritis, joint and ligamentous
laxity,autoimmune diseases, patellofemoral
arthrosis, genu valgum… Kurtz [10] on a
study of 8 million Hip and Knee arthroplasty
in the NIS (Nationwide Inpatient Sample)
found 58.6% of women.
This difference may reflect a greater willin-
gness of women to receive an arthroplasty, but
most studies on the subject show a more seve-
re clinical score in women before the interven-
tion than in men. At similar symptom levels,
women appear to be more reticent to undergo
a knee arthroplasty [12-15]. Regarding the per-
centage of women undergoing UKA (Table 9),
there is considerable variability in different
published series, as indications for the surgery
differ; the 83% of women in our own series
[16] can be explained by our selection crite-
rion of weight <85 kg although currently, we
do not take into account the criterion of sex,
when selecting patients for UKA. The influen-
ce of gender in the outcome of TKA has been
studied specifically with the development of
“gender” implants, and most of these studies
found no significant difference [3, 15, 17].
Regarding the UKA several retrospective
series found no influence of gender in the
results [18-22] but Deshmukh [5] notes a
worse outcome among young men, and Tabor
[4] showed a greater survival among women
after 10 years. However none of these studies
14
es
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296
Author/source
Implant’s number
Woman percentage
Soohoo NF [23]
222 684
62 %
Swedish’s register
138 255
70 % (1975) 61 % (2008)
Australian’s register
164 764
57.4
Norwegian’s register
28 427
69 %
Rand JA [24]
11 606
55 %
Furnes O [25]
3 032
74 %
Table 8: Proportion of women in TKA