An arthroscopically assisted proximal extensor mechanism realignment procedure has been designed and performed on 27 knees in 24 patients. The study group has been followed a minimum of 18 months. The procedure consists of a lateral retinacular release and an arthroscopically controlled plication of the medial patellar retinaculum and oblique fibers of the vastus medialis. The indications for this procedure include recurrent patellar instability and acute initial patellar dislocation with a concomitant fracture of either the patella or lateral margin of the intertrochlear sulcus. Using a simple subjective rating system for the patellofemoral joint, 25 of the 27 knees (92.5%) were subjectively rated good or excellent by the patient. Objective criteria also indicated a high success rate. There were two recurrent subluxations. There were two relatively minor complications. The average time for return to full presurgical activities, including previous sports, was 4 months.