Intrailiac Osteotomy With Superior Lateral Outcropping Bone: A Previously Undescribed Procedure for Hip Subluxation in Cerebral Palsy

Background: Surgical treatment of hip subluxation in cerebral palsy typically involves proximal femoral osteotomy with or without concurrent supra-acetabular pelvic osteotomy. The literature lacks data on isolated pelvic osteotomy for this condition. We present superior lateral outcropping bone as a novel procedure for augmenting pelvic osteotomies for additional femoral coverage. Methods: In this retrospective case series, all patients were included for whom a single surgeon at a single institution performed pelvic osteotomy with adjunctive superior lateral outcropping bone for the treatment of hip subluxation in cerebral palsy over a 12-year period. Patients with less than two years of X-ray follow-up were excluded, as were patients with frank dislocation preoperatively. Regarding each case, multiple variables were collected, including X-ray measurements of migration percentage and acetabular index preoperatively, immediately postoperatively, and at last available X-ray. Paired t tests were performed to confirm a significant difference between preoperative and postoperative measurements. Surgical failure was defined as either any subsequent hip or pelvic procedure other than myotendinous lengthening or alcohol nerve blocks, or final migration percentage of greater than 50%. Results: Thirty-three hips (23 patients, 13 males) were included. Mean age at surgery was seven years. Mean time to follow-up was 49 months. Migration percentage of the hips improved from an average 44% preoperatively to 25% at first postoperative measurement and 22% at final follow-up (p < 0.001). Acetabular index improved from an average 27 degrees preoperatively to 15 degrees at first postoperative measurement and 17 degrees at final follow-up (p < 0.001). No hips met failure criteria of repeat surgery other than myotendinous lengthening or nerve blocks, but two presented with a migration percentage of greater than 50% at final follow-up, giving us a failure rate of 6%. Conclusions: We present a novel procedure that appears to provide safe and successful outcomes for hip subluxation in cerebral palsy. Our clinical results compare favorably to those in the literature for isolated proximal femoral osteotomy for similar patient populations, yet there is no need for implanted hardware.