Flexion osteotomy in the treatment of avascular necrosis of the hip.

The natural history of untreated nontraumatic avascular necrosis of the femoral head has a very poor outcome because of the high percentage of collapse of the head. Among the more conservative surgical treatments available, flexion intertrochanteric osteotomy, aimed at rotating the intact posterior portion of the femoral head into the weightbearing portion of the acetabulum, gives satisfying long-term results when planned and performed carefully on selected patients. In general, this includes young and highly motivated patients who have a diagnosis of Ficat Stage II or Stage III idiopathic avascular necrosis. According to the Merle d'AubignÞ hip score, avascular necrosis with a complete or slightly reduced range of motion represents the best indication. The results of this procedure on 24 patients at a mean followup of 122 months were satisfactory in 15 patients (62.5%). Nine patients (37.5%) had a conversion to total hip arthroplasty, none of which was associated with technical difficulties related to the initial surgical procedure. Pain and walking ability improved in all patients postoperatively compared with preoperatively, although improvement in range of motion was not observed.