Arthroscopic treatment of voluntary superior dislocation of the patella.

The patient, a 45-year-old woman who complained of crepitation and locking of her patella, had a voluntary superior dislocation of the patella and was arthroscopically treated. Radiography showed patella alta and osteoarthrosis in the patellofemoral joint. Fluoroscopy showed that, during active contraction of the quadriceps muscle, the tip of the osteophyte on the inferior edge of the patella was positioned at the same level as the osteophyte on the superior margin of the articular surface of the medial femoral condyle. The inferior edge of the patella could be made to catch on the femoral osteophyte by application of slight pressure to the patella. Arthroscopic resection of the osteophte was performed, and the postoperative course was uneventful. The patient reported no difficulty when she was last seen 1 year after the operation.