Introduction. A transtrochanteric curved varus osteotomy (TCVO) is an excellent joint preserving surgical modality if the necrotic lesion can be moved to the non-weight bearing area as assessed by maximum abduction antero-posterior radiographs. The purpose of this article was to elucidate whether TCVO can reduce the volume of osteonecrosis after an index osteotomy as assessed by magnetic resonance imaging (MRI). Methods. Twenty patients (twenty hips) with non-traumatic osteonecrosis of the femoral head were followed for more than three years after an index operation and MRI examinations both before and at two years after surgery were retrospectively investigated. The average age at the time of operation was 40 years (range, 18 to 60 years), consisting of 13 men (13 hips) and 7 women (7 hips). The etiology and/or associated risk factors was steroid-associated osteonecrosis in 11 hips, alcohol associated in 7 hips, and idiopathic in 2. According to the classification of the Japanese Investigation Committee there was Type B in one hip, Type C-1 in 17 hips, and Type C-2 in 2 hips. Eight hips were in Stage 2, 10 in Stage 3A, and 2 in Stage 3B. Average follow-up was 4 years (range, 3 to 5 years). Results. The average varus angle was 26.5 degrees (range, 15 to 35 degrees), and the average leg length shortening was 11.8 millimeters (range, 2.5 to19 millimeters). The pre-operative average Harris hip score improved from 68 points to 97 points three years after TCVO. The bone union of the osteotomy was obtained at an average of 4 months (range, 3 to 8 months). A progression to collapse of the femoral head was observed in three hips. The pre-operative average necrotic volume by MRI was 12.8 cm. 3. (range, 6.4 to 20.9 cm. 3. ) and at two years after surgery the average necrotic volume significantly decreased to 9.2 cm. 3. (range, 1.7 to 16.3 cm. 3. ). Conclusion. The volume of osteonecrosis of the femoral head significantly decreased at two years after TCVO. The early clinical and radiographic results of TCVO were satisfactory

Introduction. The purpose of this study was to investigate the long-term outcome of Sugioka's transtrochanteric rotational osteotomy (TRO) for nontraumatic osteonecrosis of the femoral head. Methods. Seventy-eight patients (87 hips) were consecutively treated by TRO from 1989 to 1994. All patients followed 15 years or more were included. Four patients (4 hips) with traumatic osteonecrosis and five patients (5 hips) followed less than 15 years were excluded. A total of 69 patients (78 hips) were included. Average age at the time of operation was 42 years. There were 51 men (57 hips) and 18 women (21 hips). The average follow-up was 17 years (range, 15 to 20 years). Type of osteonecrosis was as follows: Type B; 2 hips, Type C1; 50 hips, and Type C2; 26 hips. Stage was as follows: stage 2; 29 hips, stage 3A; 34 hips, stage 3B; 13 hips, and stage 4; 2 hips. Transtrochanteric anterior rotational osteotomy was performed in 76 hips and posterior rotational osteotomy was performed in 2 hips. Clinical evaluation was evaluated by Harris hip score. Kaplan-Meier survivorship analysis was performed based on the end point of conversion to total hip arthroplasty (THA) or re-collapse. Results. Twenty-nine hips (37.2%) were converted to THA, and 38 hips (48.7%) were re-collapsed. Average Harris hip score before operation was improved from 67 to 82 points at final follow-up. The reasons for conversion to THA within five years after osteotomy were cervical fracture or fixation failure, and 10 years after osteotomy progression of osteoarthritis due to re-collapse. Kaplan-Meier survivorship at 10 years after surgery was 69.2% (95% confidence interval: 58.8-79.6) and 15 years after surgery was 61.3% (95% CI: 49.9-72.7) with THA as the end-point. Kaplan-Meier survivorship at 10 years after surgery 50.0% (95% CI: 38.6-61.4) and at 15 years after surgery 50.0% (95% CI: 38.6-61.4) when re-collapse was defined as the end point. Type C1 was significantly better than Type C2. There was no significant difference between the corticosteroid-induced and non-corticosteroid-induced patients. There was no significant difference between the patients with early and late stage. Conclusion. The long-term outcome of transtrochanteric rotational osteotomy for osteonecrosis of the femoral head was excellent. Sixty-three percent of the hips were not converted to THA. Type C2 was a significant risk factor for TRO