Table 3.
Influence of component alignment on the preoperative-postoperative difference in patellar kinematics estimated with generalized linear models
| ML-shift a
|
Epicondylar distance a
|
|||
|---|---|---|---|---|
| Parameter | Estimate b (95% CI) | p-value | Estimate b (95% CI) | p-value |
| Flexion | ||||
| 30° | 1.3 (–0.2 to 2.9) | 0.1 | 4.1 (0.4 to 7.9) | 0.02 |
| 45° | 1.1 (0.0 to 2.4) | 0.1 | 4.3 (0.9 to 7.7) | 0.01 |
| 60° | 1.0 (0.3 to 1.8) | < 0.01 | 2.4 (0.4 to 4.5) | 0.01 |
| 75° | 0.5 (0.0 to 1.1) | 0.1 | 2.5 (0.8 to 4.3) | < 0.01 |
| 90° | reference | reference | ||
| Flexion, FC (per 1°) | 0.5 (0.0 to 1.1) | 0.04 | 0.6 (0.0 to 1.2) | 0.03 |
| Flexion, FC | ||||
| Flexion a | ||||
| 30° | –0.1 (–0.5 to 0.2) | 0.5 | –0.5 (-1.0 to 0.0) | 0.1 |
| 45° | –0.1 (–0.4 to 0.2) | 0.4 | –0.3 (-0.9 to 0.1) | 0.1 |
| 60° | –0.1 (–0.3 to 0.0) | 0.2 | –0.2 (-0.5 to 0.0) | 0.1 |
| 75° | 0.0 (–0.3 to 0.2) | 0.9 | 0.0 (-0.2 to 0.1) | 0.6 |
| 90° | reference | reference | ||
| Posterior slope, TC (per 1°) | 0.4 (–0.2 to 1.1) | 0.2 | 0.9 (0.3 to 1.4) | < 0.01 |
| Posterior slope, TC | ||||
| Flexion a | not included | |||
| 30° | –0.5 (–1.1 to 0.0) | 0.1 | ||
| 45° | –0.5 (–1.1 to 0.0) | 0.1 | ||
| 60° | –0.2 (–0.5 to 0.1) | 0.2 | ||
| 75° | –0.3 (–0.6 to 0.0) | 0.04 | ||
| 90° | reference | |||
| Rotation FC (per 1°) | –0.1 (–0.3 to 0.0) | 0.2 | 0.0 (-0.1 to 0.1) | 1.0 |
a
Difference in preoperative and postoperative values.
b
The estimate of each parameter gives the change in ML-shift or epicondylar distance either per one unit change in the parameter or in relation to the reference category. For example, by changing flexion from 90° to 60°, the difference (pre-post) in the ML-shift will increase by 1.0 mm and decrease by –0.1 times the flexion of the femoral component.
FC: femoral component
TC: tibial component