抄録
Objective: The gap balance has a relationship with the flexion angle in total knee arthroplasty (TKA), and the rotational position of the femoral component influences the gap balance in flexion. The objective of this study was to determine the relationship between the rotational position and the flexion angle after TKA.
Methods: Ninety-eight knees treated by posterior-stabilized TKA were evaluated in this study. The condylar twist angle (CTA) was measured, using the epicondylar view technique reported by Kanekasu et al., as the deviation of the posterior condylar axis (PCA) from the clinical epicondylar axis (CEA) at 1 year after the operation. Knees with external rotation compared with the CEA were assigned to the external rotation group, those positioned between the surgical epicondylar axis (SEA) and the CEA were assigned to the middle group, and those with internal rotation compared with the SEA were assigned to the internal rotation group. The flexion angle was measured for all knees.
Results: The external rotation group (n=12) had a CTA of 1.6°±1.0° and a flexion angle of 129.3°±9.4°, the middle group (n=37) had a CTA of -1.3°±1.1° and a flexion angle of 124.2°±12.5°, and the internal rotation group (n=49 knees) had a CTA of -5.4°±1.7° and a flexion angle of 118.4°±11.0°. The flexion angle in the internal rotation group was significantly lower than that in the external rotation group (p<0.05).
Conclusion: These results suggest that the flexion angle is lower when the femur component is placed in an internally rotated position relative to the SEA, compared to the angle when the femur component is placed in an externally rotated position relative to the SEA.
