Valgus extension femoral osteotomy to treat "hinge abduction" in Perthes' disease.

PURPOSE "Hinge abduction" is a complication of Perthes' disease caused by impingement of the extruded superolateral portion of the femoral head against the lateral lip of the acetabulum. Catterall first described femoral valgus extension osteotomy (VGEO) to treat this condition. We report the results of this operation in 16 cases of Perthes' disease with "hinge abduction". METHODS Sixteen hips in 16 patients affected by Perthes' disease and "hinge abduction" were operated on at a mean age of 10.1 years and followed up an average of 6.5 years later. Before surgery, the mean Iowa hip score was 44.4 points. Preoperative radiographs were taken with the affected hip in maximum adduction in order to calculate the amount of valgus correction. The osteotomy was performed between the greater and the lesser trochanter, and it was fixed with a hip plate. RESULTS All the osteotomies healed uneventfully. At follow-up, no patient complained of pain and hip abduction ranged from 20° to 45°. Four out of the 16 patients had a moderate limp, and 12 had an improvement in gait pattern compared to preoperatively. At follow-up, the Iowa hip score totaled a mean of 83.6 points, with a statistically significant improvement in comparison to the preoperative evaluation. At follow-up, two hips were classified as Stulberg II-III, ten hips as Stulberg III, and four as Stulberg IV. CONCLUSIONS In our hands, VGEO was an effective procedure to treat "hinge abduction" in severe Perthes' disease with satisfactory results. The main limitation of our study is its short follow-up.