Abductor length alterations in hips with SCFE deformity.

Abstract

Proximal femoral osteotomy may improve clinical outcomes in patients with residual deformity after slipped capital femoral epiphysis. Whether this procedure improves abductor mechanics is not well established. We hypothesized that abductor lengths would be shorter in patients with slipped capital femoral epiphysis compared with normal controls, and a femoral neck base osteotomy would create more normal abductor lengths than an osteotomy performed below the greater trochanter. Abductor muscle lengths were measured in normal, mild, and severe slipped capital femoral epiphyses sawbone models and after two methods of surgical correction. We observed decreases in abductor lengths in patients with slipped capital femoral epiphysis compared with normal controls when positioned in greater than 45 degrees flexion. There were fewer differences in abductor lengths after femoral neck base osteotomies than after subtrochanteric osteotomies. The femoral neck base osteotomy approximated normal abductor lengths more closely than the subtrochanteric osteotomy. The femoral neck base osteotomy restored the hip abductor relationship better than an osteotomy performed below the greater trochanter. We did not address the question of whether this improved relationship directly influenced function.