Component design affecting patellofemoral complications after total knee arthroplasty

Three hundred one primary cemented total knee arthroplasties were performed in 289 patients. Two different prostheses were used; 148 knees received the Miller-Galante I prosthesis and 153 knees received the Press Fit Condylar prosthesis. Minimum followup was 2 years. The groups were similar in all parameters both preoperatively and postoperatively, with the exception of the patellofemoral complication rate. Knees that were implanted with the Miller-Galante I prosthesis experienced a complication rate of 10.1%, while those with the Press Fit Condylar prosthesis experienced a complication rate of 0.7%. The distinct difference in the patellofemoral complication rate may be due to the differences in design of the femoral component. Features that may have contributed to increased patellofemoral morbidity included a short, narrow anterior flange; a shallow patellar groove; and an abrupt anterior to distal transition with a smaller radius of curvature. Because subtle design difference can have a profound effect on clinical outcome, long term evaluation of new designs should be completed before widespread use. The clinician also should be aware of the desirable design features when choosing a component.