A New Modified Technique of Triple Osteotomy of the Innominate Bone for Acetabular Dysplasia

Abstract

A new modified technique of triple osteotomy of the innominate bone has been devised and implemented for the treatment of residual acetabular dysplasia in children with developmental dysplasia of the hip. The procedure is done through a two-incision approach. The ischium, pubis, and iliac bones are osteotomized, with resection of a triangular wedge of bone from the outer cortex of the proximal part of the ilium. The resection of the triangular wedge of bone from the outer cortex alone creates a slot with the intact inner cortex serving as a stabilizing abutment where the distal posterior aspect of the ilium fits. This osteotomy allows for extensive coverage of the femoral head with greater stability. The stable construct of the osteotomy and pelvic fixation facilitates early weight bearing and obviates the need for hip spica cast immobilization. Since its conception the new triple osteotomy has been done in 11 children (13 hips). The preoperative vertical center edge angle of Weiberg was 8.9 degrees (range, 5 degrees -17 degrees ). The postoperative vertical center edge angle was a mean of 45.6 degrees (range, 31 degrees -58 degrees ). The last followup vertical center edge angle was a mean of 44.9 degrees (range, 29 degrees -58 degrees ). The mean preoperative acetabular angle of Sharp was 53 degrees (range, 48 degrees -61 degrees ). The postoperative acetabular angle was a mean of 25.4 degrees (range, 19 degrees -40 degrees ). The last followup acetabular angle was a mean of 28 degrees (range, 18 degrees -41 degrees ). All patients went on to have bony unions on their innominate bone. We describe the technique for the osteotomy and presents preliminary results of all patients who had the procedure.