Abstract
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 cm3 (range, 6.4 to 20.9 cm3) and at two years after surgery the average necrotic volume significantly decreased to 9.2 cm3 (range, 1.7 to 16.3 cm3).
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.
