Femoral rotation influences dynamic alignment of the lower extremity in total knee arthroplasty / 中华骨科杂志

ABSTRACT

Objective To evaluate the influences of femoral rotation on dynamic alignment of the lower extremity in TKA by computer assisted surgical technology.Methods From July 2013 to August 2013,76 consecutive patients with knee osteoarthritis undergone primary-single TKA in our hospital were enrolled,including 46 males and 30 females,aged from 64 to 78 years (average,71 years).All surgeries were completed by the same professional doctor.The PFC (fixed-bearing posterior stabilized) Sigma rotating-platform was selected for all patients,and computer navigation system (Stryker(R) Navigation System Ⅱ-Cart (Stryker corporation,Kalamazoo,Michigan,USA) was used.External rotation osteotomy of the distal femur during TKA was completed according to the pre-operative external rotation angle (ERA),intraoperative transepicondylar axis (TEA) and anteroposterior (AP) line.Passive dynamic alignment of the lower extremity during knee flexion was recorded.The variation trend of hip-knee-ankle (HKA) alignment and the influences of femoral external rotation osteotomy were analysed.Results ERA calculated by the computer navigation system according to Whiteside line,TEA and the mean of Whiteside line and TEA was 5.54°±2.86°,5.21°±2.60° and 5.34°±2.38°.Compared with the ERA measured by CT,no method was better than the other two.Postoperative deviation of HKA alignment from 0° to 90° flexion was associated with the rotational alignment of the femoral component.Trend of HKA alignment during knee flexion tended to be varus,valgus or neutral according to different angles of external rotation osteotomy of the distal femur.Conclusion The HKA alignment changes during the knee flexions.External rotation osteotomy of the distal femur played a crucial role in determining dynamic HKA alignment in TKA.