Rotational alignment of femoral component and flexion gap balance in patients with distal femoral torsional deformity using navigation-assisted TKA.

Abstract

We evaluated the rotational alignment of the femoral component after total knee arthroplasty in 46 patients with distal femoral torsional deformity using a navigation-assisted gap technique. Preoperative distal femoral torsional angle and postoperative rotational deviation of the femoral component were measured using computed tomography. Flexion gap data were obtained from intraoperative navigation measurements. The mean rotational deviation of the femoral component was 4.1 degrees (range, 2 degrees -6 degrees ) internal rotation in reference to transepicondylar axis (TEA). The femoral component was not aligned within 3 degrees in reference to TEA in 30 patients (65.2%). There was no significant difference of rotational deviation of the femoral component between unbalanced and balanced flexion gap groups (P=.65). There was a significant improvement of clinical outcomes after TKA. Navigation-assisted gap technique provided balanced flexion gaps in most patients, although there were wide rotational deviations of femoral components. Using the anatomic bony landmark method can result in excessive external rotation of the femoral component and unbalanced flexion gaps in patients with distal femoral torsional deformity.