The pathological anatomy of chronically dislocated hips makes reconstruction for more difficult in them than in most cases. The acetabular component must be seated at the site of the original triradiate cartilage and the femur must be shortened four or more centimeters to prevent excessive limb lengthening. This means that the femoral component must be seated in the smallest, strightest portion of the intramedullary canal. A specially designed prosthesis is often needed. Twenty-two hips were operated on in this series, and all patients had relief of pain and improvement of gait. One major complication occured: a sciatic-nerve palsy due to overlengthening of the femur and improper postoperative positioning.