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using Microsoft Excel (Microsoft Corp,
Redmond, WA, USA). We compared the
angle’s measurements between lateral UKA
and medial UKA. Correlations between
variables were calculated using the Pearson
product moment coefficient of correlation (r).
The significance level was set at 0.05.
RESULTS
(table 1)
The femoral component rotation averaged -
1.2° (SD 7.3; -12.9° to 14.6°). The femoral
component was in external rotation for a
medial UKA (mean 3.2°; SD 7.3; -6.6 to 14.6)
and in internal rotation (mean -5.8°; SD 7.18;
-12.9 to 4.6) for a lateral UKA. The difference
in rotation angle between compartments was
statistically significant (p<0.0001). There was
no correlation between femoral implant rota-
tion and the mFTA.
The tibial implant frontal inclination averaged
86.6° (SD 4; -12.3 to 5.3). For the medial
UKA, the tibial component was always in
varus with a mean inclination of 84.5° (SD
2.7; 77.7 to 89.4). For the lateral UKA, a slight
valgus was found with a mean inclination of
91.3° (SD 4.0; 84.7 to 100.1). The difference
in tibial component varus/valgus angles for
medial and lateral components was statistical-
ly significant (p<0.0001). There was no corre-
lation between the frontal tibial inclination and
the mFTA. The tibial slope averaged 85.3° (SD
4.6; -15.9 to 6.7) with no difference between
the medial UKA and the lateral UKA
(p=0.432). The tibial implant rotation was
positioned in external for both medial and late-
ral UKA. There was no correlation between
femoral implant rotation and tibial implant
rotation.
THREE-DIMENSIONAL ANALYSIS OF UNICOMPARTIMENTAL KNEE IMPLANT POSITIONING
175
Fig. 2: Tibial rotation angle with a mean exter-
nal rotation of 6.9°.
UKA Lateral UKA Medial UKA
p
(n=37)
(n=18)
(n=19)
Tibial Rotation
6.9°
7.4°
6.5°
ns (0.717)
(n=37)
(7.94 ;
(10.25 ;-
(5.1 ;-
-13.9-30.3°)
13.9-30.3°)
6.0-13.2)
Frontal Inclination
86.6
91.27°
84.5°
0.0000.
TIBIA
(n=37)
(4.00 ;
(4.0;
(2.7;
77.7-100.1)
84.7-100.1)
77.7-89.4)
Sagittal Inclination
85.3°
84.69°
85.79°
p=0.432
(n=37)
(4.6;
(4.49 ;
(4.56 ;
-15.9-6.7)
74.1-96.7)
78.9-93.4).
Femoral Rotation
-1.2°
-5.8°
3.2°
0.0000.
FEMUR
(n=37)
(7.3;
(7.2;
(7.3;
-12.9°-14.6°)
-12.9 - 4.6)
-6.6 - 14.6)
Table 1
ns = non significant