Patellofemoral osteoarthritis is a common disease which may occur alone or in association with tibiofemoral gonarthrosis. In cases of isolated symptomatic patello-femoral osteoarthritis with typical lateral malalignment and formation of osteophytes at the lateral border of the patello-femoral joint we perform a lateral facetectomy of the patella and associated lateral retinaculum release. The results of a prospective study of 20 cases with a mean follow-up of 2 years are presented. A good-to-moderate result was obtained in 90%. The average age was 60 years. We had 2 failures with a subjective rating of poor. The principal reason was tibiofemoral gonarthrosis too far advanced at the time of the operation, which then progressed in the postoperative course. On the other hand this technique results in marked improvement for many cases and carries only a small risk. Further reconstructive surgery of the knee is not excluded. Because of the minor surgery and quick recovery, this operation presents a valid alternative to more involved operations such as patellectomy, Bandi or Maquet reconstructive procedures, or a patellofemoral prosthesis.