Morscher's femoral neck lengthening osteotomy through surgical hip dislocation approach for preservation of Perthes and Perthes-like deformities

Background: Typical sequelae of Perthes disease and Perthes-like deformities comprise a short femoral neck, aspherical femoral head, and greater trochanteric overgrowth. Morscher's osteotomy aims at restoring the normal extra-articular anatomy, but incapable of restoring a normal head-neck contour with residual impingement. Femoral neck lengthening osteotomy combined with osteochondroplasty through surgical hip dislocation approach was not previously described in the literature. We hypothesized that this technique is capable of near-normal restoration of the proximal femoral anatomy, increasing limb length, restoring abductor power, and simultaneous management of intra-articular chondro-labral disease. Methods: A prospective series of 21 consecutive patients with sequelae of Perthes disease and Perthes-like deformity (Stulberg II and III) were treated by Morscher's osteotomy through surgical hip dislocation approach. The mean age was 14.9 years (9-30 years) and the mean follow-up was 4.5 years (2-8 years). Results: The mean Harris hip score improved significantly from 66.5 to 89.5 points (p < 0.001), and the mean limb length discrepancy improved from 2.5 to 0.6 cm (p < 0.001). The mean alpha angle improved from 81.8 degrees to 49.5 degrees, the mean neck-shaft angle increased from 117.8 degrees to 129.8 degrees, and the articulo-trochanteric distance has improved from -6.7 to 20.8 mm. Six out of 21 patients required staged periacetabular osteotomy for residual acetabular dysplasia. No cases of chondrolysis or osteonecrosis were identified. Conclusion: Femoral neck lengthening osteotomy through surgical hip dislocation appraoch has proven to be safe and effective for preservation of symptomatic hips with Perthes and Perthes-like deformities and mild to moderate femoral head deformities (Stulberg II and III). A staged periacetabular osteotomy may be required in those patients with significant acetabular dysplasia.