The Repair Process of Osteonecrosis After a Transtrochanteric Rotational Osteotomy

Abstract

Many studies have reported the factors influencing the progression of collapse and development of osteoarthritis after a transtrochanteric rotational osteotomy. It is not well understood how the healing process of the osteonecrotic area occurs after this procedure. We evaluated (1) the osteonecrotic area after a successful transtrochanteric rotational osteotomy radiographically; and (2) determined whether specific perioperative clinical and radiographic factors related to the difference(s) in the healing process after a transtrochanteric rotational osteotomy. We retrospectively reviewed 64 patients (70 hips) among 402 patients (507 hips) who had a transtrochanteric rotational osteotomy between 1981 and 1996 and showed no evidence of progression of collapse or joint space narrowing at 10 years after the osteotomy. Forty-eight hips (45 patients) were males and 22 (19 patients) were females, with a mean age of 37 years (range, 12-57 years) at the time of surgery. An anterior rotational osteotomy was performed for 57 hips and a posterior rotational osteotomy was performed for 13 hips. We recorded various perioperative factors potentially influencing repair and assessed the radiographs at last followup for various features indicating repair. Ten years after the transtrochanteric rotational osteotomy, the osteonecrotic area in 50 hips (71%) had osteosclerotic changes radiographically (Group I), while 20 hips (29%) had normal bony architecture without sclerotic changes (Group II). We observed no difference between Groups I and II with regard to the age, gender, use of corticosteroids, etiology, and radiographic stage. Although the reason for this difference in the healing patterns remains unknown, this study indicates the majority of the hips showed osteosclerosis after a transtrochanteric rotational osteotomy, while approximately 30% of the hips showed a normal bony architecture.