ANATOMIC BASIS OF TONNIS TRIPLE PELVIC OSTEOTOMY FOR ACETABULAR DYSPLASIA

Dysplasia of the hip in adults can be treated by a pelvic osteotomy. I n order to assess pelvic anatomy in relation to surgical approach and osteotomy sites, 12 cadaver hips were studied. A triple pelvic osteoto my as described by Tonnis [6] through ilium, pubis and ischium was per formed, followed by an intrapelvic and anterior and posterior dissecti on of the hip. At the ischium, the pudendal and inferior gluteal neuro vascular bundles are most at risk medially and proximally respectively . Much less in danger is the sciatic n. as it runs 1 to 3 cm lateral t o the osteotomy site. At the pubis osteotomy the femoral v. lies close on the bone and is prone to damage. The artery lies further off the b one. The ilium osteotomy starts just proximal to the anterior inferior iliac spine and exits posteriorly at the sciatic notch. Here the scia tic n. and the superior gluteal neurovascular bundle may be damaged. T he practical surgical implications of these three osteotomies an discu ssed, especially with respect to the requirement of meticulous subperi ostal dissection and accurate placement of retractors.