Patellofemoral arthroplasty - An update

The rationale for presenting this updated study is to report long-term clinical and survival results of patellofemoral arthroplasty and to ascertain whether the preoperative diagnosis influenced outcomes and therefore indications. We retrospectively updated a previous evaluation of 66 patients who had unilateral patellofemoral arthroplasty between 1972 and 1990. The mean age of the patients at the initial surgery was 57 years (range, 21-82 years). The patients had an average followup of 16.2 years (range, 12-20 years). Preoperative diagnosis included instability, fracture, and primary arthritis. Revision surgery was done in 14 patients for femorotibial osteoarthritis, in 11 for loosening, and in four for stiffness. Survivorship was 58% at 16 years. The knee function score improved from 40 points preoperatively to 81 points at last followup. The best results were in patients with preoperative instability and corrected alignment of the extensor mechanism. Stiffness occurred only in those patients with osteoarthritis from previous fracture. Progressive degeneration of the tibiofemoral joint was noted mainly in the primary osteoarthritis etiologic group. This long-term evaluation of patellofemoral arthroplasty showed the importance of patient selection while excluding knees with significant frontal tibiofemoral malalignment.