The Richards type II patellofemoral arthroplasty: 26 cases followed for 1-20 years.

We followed 26 Richards type II patellofemoral arthroplasties in 24 patients (19 women) for a mean of 11 (1-20) years. Their mean age was 59 (22-90) years. The preoperative diagnoses were primary patellofemoral arthrosis in 17 cases and secondary arthrosis in 9 (8 malalignment, 1 patellar fracture). Patellectomy was later performed for persistent pain or patellar malalignment in 3 cases and a conversion to a total knee arthroplasty for progressive tibio-femoral degeneration or patella malalignment in 2. The mean Knee Society knee score for 21 knees at follow-up was 90 (65-100) points. The patients rated the results of surgery in 9 knees as excellent, 7 good, 4 improved, and 1 unimproved at follow-up. None of the implants showed signs of loosening or infection. The Richards type II patellofemoral arthroplasty yields acceptable long-term results in patients with isolated end-stage patellofemoral osteoarthrosis. Patient selection and patella alignment are important.