Elongation of the femoral neck in Perthes disease.

We present the long-term clinical and radiological results of a series of 168 young patients with unilateral Perthes disease who were treated in our department between 1989 and 1997, using a combined osteotomy in the longitudinal and horizontal axis of the proximal femur and elongation of the femoral neck. Surgical treatment was undertaken for any group II (Catterall's classification) patient, with the presence of two or more radiographic signs of the "head at risk" and the clinical sign of flexion with abduction, as well as for all cases classified by Catterall as groups III and IV. The surgical procedure we describe provided 147 radiologically and clinically normal hips in the short and long-term. However, in the long-term, 21 out of 168 patients presented with residual deformities such as shallow acetabulum, thickening of the acetabular floor, coxa magna, thicker and slightly shorter femoral neck. Thus for the vast majority of patients, the operation we describe here provided leg length equalisation and restored the working length of the abductors by maintaining the tip of the greater trochanter at the same level as on the unaffected side.