Increase of patellofemoral height has decreased maximum knee flexion after total knee arthroplasty of posterior cruciate-substituting prosthesis in a clinical series.

Abstract

Biomechanical studies in vitro suggested that patellofemoral (PF) stuffing would cause knee flexion restriction after total knee arthroplasty (TKA). We investigated the effect of anterior PF stuffing on the postoperative knee flexion after cemented TKA of posterior cruciate-substituting (PS) design. A retrospective review of 140 primary TKAs for osteoarthritis with an average age of 68.5 was conducted. The patella was resurfaced. The height of PF joint and the patella thickness were evaluated radiographically, preoperatively and 2-year postoperatively. The maximum flexion angle was 129.7° (standard deviation: SD 16.9) pre-operatively and 129.3° (SD 11.9) 2-year postoperatively. The increase in height was associated with the differences in maximum flexion angle between preoperatively and postoperatively (R = 0.254 P < 0.01). The patella thickness change did not show any significant influences. The increase in patellofemoral volume has decreased range of motion after total knee arthroplasty of posterior cruciate-substituting prosthesis.