Surgical treatment of patellar instability: indications and results.

The purpose of this study was to evaluate a consecutive series of 465 patients with patellar subluxation. Both knees were involved in some patients. Therefore, 557 knees were studied. The average age was 24 years. Specific symptoms and signs were reviewed. Instability, swelling, and patella alta were more common in the group requiring surgery. All patients were treated conservatively with specific exercises initially. Failure of this conservative treatment to significantly improve the symptoms, inability to do the activities of daily living, or expected associated pathology were indications for surgery. Surgery was required in 139 patients (27%). Some patients had surgery on both knees. Therefore 149 knees were repaired. The surgical technique consisted of an extensor mechanism realignment. This consisted of release of the lateral patellofemoral ligaments, advancement of the vastus medialis obliquus muscle and, in some cases, transfer of the tibial tubercle. Arthrotomy was done in all cases. Results were evaluated in terms of pain, function, and patellar instability. Signs evaluated preoperatively and postoperatively were tenderness of the retinaculum or bone, patellar mobility, effusion, muscle atrophy, and tone. Range of motion was also evaluated. The average followup lasted three years.