Does mismatch of the femoral component aspect ratio

Abstract

【Abstract】Objective: To study whether the range of knee flexion (ROF) is affected by geometrical mismatch of the femoral component and the resultant change in the pos-terior condylar offset (PCO) after high-flexion posterior-sta-bilized total knee arthroplasty (TKA). Methods: One hundred osteoarthritic patients (50 males and 50 females) underwent femoral osteotomy by the ante-rior referencing technique. The PCO for each patient was measured from lateral radiographs before, during and 2 years after TKA. The thickness of the joint cartilage was mea-sured by magnetic resonance imaging before TKA and added onto the radiographic measurement. The relationship be-tween changes in the PCO and improvements in the ROF before, during and 2 years after TKA were statistically analyzed. Results: Compared with the preoperative value, the PCO was reduced by (3.45±3.28) mm after TKA, with a sig-nificantly larger reduction observed in female patients than male patients (P<0.05). When examining the subject popu-lation as a whole, there was a significant positive correla-tion between PCO and ROF improvement during TKA (P< 0.05), but this improvement was not maintained 2 years after TKA (P>0.05). However, when male and female patients were analyzed separately, there was a significant positive corre-lation between PCO change and ROF improvement for both sexes at both time points (all P<0.05). Conclusions: Restoration of PCO plays an important role in the optimization of knee flexion even after posterior-stabilized TKA. Femoral components based on Caucasian anatomic characteristics could not match the native anatomy of distal femurs in Chinese population especially female Chinese. Rotated resection of distal femur with anterior re-ferencing technique usually leads to a decreased PCO and therefore reduces maximal obtainable flexion. Key words: Arthroplasty, replacement, knee; Pros-thesis design; Range of motion, articular; Femur