Patellofemoral osteoarthritis treated by partial lateral facetectomy: results at long-term follow up.

Excision of the eroded lateral patellar facet has been suggested as an acceptable treatment for short-term pain reduction in patients with isolated patellofemoral osteoarthritis. The outcome of this procedure at long-term is however not known. We therefore reviewed the results of 155 consecutive patients (168 knees) treated at our institution with lateral facetectomy at an average follow up of 10.9 years (± 6.9 years SD). During follow up 62 knees (36.9%) had failed and were revised to either TKA (60 knees), patellofemoral arthroplasty (one case) or total patellectomy (one case). Average time to reoperation in the failure group was 8.0 years (± 6.2 years SD). Kaplan-Meier survival rates with reoperation as endpoint were 85% at 5 years, 67.2% at 10 years, and 46.7% at 20 years respectively. At final follow up 79 (74.5%) of the knees that had not been re-operated were rated as either good or fair, which corresponds to 47% of the original group. Our study therefore demonstrates that a satisfactory outcome after lateral patellar facetectomy for isolated patellofemoral osteoarthritis can be expected in approximately half of the cases at 10 year follow up.