Patellofemoral arthroplasty. A three- to nine-year follow-up study.

Twenty-two patients with 25 patellofemoral arthroplasties (resurfacing of the patella and femoral groove) were evaluated to assess long-term results. A past history of patellofemoral malalignment or instability was obtained from 14 patients. Preoperative roentgenograms demonstrated patellofemoral osteoarthritis in all 25 knees; five patients had both tibiofemoral and patellofemoral osteoarthritis. The average age at the time of surgery was 62 years and follow-up time averaged 5.3 years. Results were determined using a modified Hungerford knee rating scale. Follow-up roentgenograms were evaluated for mechanical failure and progressive deterioration of the tibiofemoral joint. Eighteen of 25 (72%) patellofemoral arthroplasties were rated excellent or good. However, 15 of 17 patellofemoral arthroplasties (88%), all performed on women, had satisfactory results. There were seven failures. The presence of tibiofemoral osteoarthritis adversely affected the outcome; excluding the five patients with tibiofemoral osteoarthritis, 17 of 20 patellofemoral arthroplasties (85%) had satisfactory results. Other reasons for failure were malposition of the components and persistent patellofemoral malalignment. Mechanical failure was not observed. Patellofemoral arthroplasty may be indicated for patients with osteoarthritis limited to the patellofemoral compartment.