Biomechanical aspects of Salter osteotomy.

A mathematical model of a Salter osteotomy in an adult male pelvis reveals that during innominate osteotomy, the center of the hip joint moves distally, posteriorly, and medially. The acetabulum extends by an angle roughly equivalent to the angle of osteotomy opening. Adduction of the acetabulum takes place to a lesser extent. Hip abductors and flexors tighten minmally following innominate osteotomy. Augmentation of abduction occurs as a result of medial acetabular displacement rather than gross alteration of the abductor muscles themselves. Theoretical considerations suggest that the surgeon should strive to obtain maximum correction at the osteotomy site while avoiding levering at the greater sciatic notch.