High-degree posterior rotational osteotomy for extensive collapsed femoral head osteonecrosis in teenagers: remodeling and results with a mean of 10-year follow-up

Abstract

Introduction: This study evaluated the effectiveness of high-degree posterior rotational osteotomy for teenagers with extensively collapsed femoral head osteonecrosis.

Materials and methods: We reviewed 40 hips in 35 patients with severely collapsed femoral head osteonecrosis treated by this procedure with a mean follow-up period of 9.7 years (range 5-25 years). Thirteen hips had a history of steroid administration. Nine had slipped capital femoral epiphysis. Nine had femoral neck fracture. Two had traumatic dislocation and fracture. Seven had no apparent risk factors. The mean age of the patients (18 women and 17 men) was 14.8 years. All femoral heads were extensively collapsed below the acetabular roof, and 20 hips showed preoperative joint space narrowing (ARCO stage 4). Lateral radiographs of the femoral head revealed extensive lesions from the posterior to anterior portion. The mean degree of posterior rotation was 118° with intentional varus positioning [mean: 19° (range 10-30)]. The pre- and postoperative extent of the viable area of the femoral head was assessed using conventional anteroposterior radiographs and 45-degree flexion radiography. Further collapse, joint space narrowing, femoral head morphology, and congruency with the acetabulum based on the Stulberg classification were assessed using conventional anteroposterior radiographs. The clinical assessment was conducted using the Merle d'Aubigné hip scores at the last follow-up.

Results: The viable area of the femoral head on the loaded portion was seen during a short period after operations. The necrotic lesions were gradually improved postoperatively. The mean extent of viable bone below the acetabular roof was 48% at less than 6 months after surgery and 92% at the final follow-up. The mean extent on 45° flexion radiography was 54% at less than 6 months after surgery and 89% at the final follow-up. Further collapse was prevented in 38 hips (95%). In 19 of 20 hips with preoperative narrowing of the joint space, the joint space was first improved, but narrowing progressively observed in 9 of 40 hips at the final follow-up. Thirty-four hips had excellent or good clinical outcomes, whereas 6 had fair or poor outcomes.

Conclusions: We concluded that this procedure is effective at delaying the progression of degeneration if adequate area of viable bone can be moved under the loaded portion of the acetabulum in teenagers with severe femoral head osteonecrosis.

Keywords: Femoral osteotomy; Osteonecrosis; Osteonecrosis of the femoral head; Posterior rotational osteotomy; Teenagers.