Modified Sugioka's osteotomy: more than 130 degrees posterior rotation for osteonecrosis of the femoral head with large lesion.

High degree posterior rotational osteotomy was performed on 31 hips with extensive osteonecrosis that were outside of Sugioka's indication. Among them, 18 hips of 13 patients were reviewed at 24 to 94 months (mean, 42 months). The remaining 13 hips were excluded because the followup was less than 2 years. All hips had less than 1/3 of the posterior area intact preoperatively, which is out of the indication for traditional anterior rotational osteotomy. The posterior rotation applied to the femoral head was 130 degrees to 180 degrees (mean, 138 degrees ). Furthermore, 10 degrees to 25 degrees of intentional varus position was added to the rotation (mean, 15.8 degrees). The preoperative intact articular surface of the loaded portion of the femoral head was 0% to 40% (mean, 6.9%) on anteroposterior radiograph, and it was extended postoperatively to a mean of 80.3% (range, 53%-100%). Collapse was prevented in 17 hips that have remained pain free. The remaining 1 hip sustained secondary collapse and joint narrowing. Mean flexion was 105 degrees and abduction was 20 degrees. Postoperative angiography of 9 hips and bony scintigraphy of 17 hips indicated no findings implying impairment of blood supply. Despite a relatively short term experience, it is concluded that this technique was effective in the treatment of large necrotic lesions, especially for young patients.