Long-term results of iliac wing fixation below extensive fusions in ambulatory adult patients with spinal disorders

Abstract

Study design: Case series, level of evidence therapeutic IV.

Objective: Examine the results of bilateral iliac wing fixation in long fusions to the pelvis in ambulatory adult patients.

Summary of background data: Adult spinal deformity surgery is an endeavor often fraught with complications. One particularly debilitating problem with long fusions of the spine in adults with spinal diseases such as degenerative scoliosis and spondylolysis is failure of the lumbosacral (spinal-pelvic) junction owing to nonunion, implant failure, or sacral fracture. This can result in continued pain, continued curve progression and deformity, progressive sagittal imbalance, and the need for reoperation. Some deformity surgeons have speculated fusion rates at the caudal end of long constructs to the sacrum could be improved by the addition of spinopelvic fixation. Iliac wing screws have been successfully used in nonambulatory patients for the treatment of neuromuscular scoliosis, but concerns exist over use in ambulatory patients. Prominence, local irritation of the screws, screw breakage, infection, and sacroiliac joint pathology are all concerns. The purpose of this study was to examine the results of long fusions to the sacrum using bilateral iliac wing screw fixation in ambulatory adults with spinal deformities.

Methods: This case series consisted of 78 patients followed for at least 2 years (average 3.7 y, range: 2 to 8 y). All patients were ambulatory adults who received bilateral iliac wing fixation below long fusion constructs (average 9 levels fused). All but 3 patients were above 50 years old and the average age in the study was 67.6 years. There were 66 females and 12 males in the study. The operative indications for posterior spinal fusion were fixed sagittal imbalance spondylolysis (23 patients), idiopathic scoliosis (22 patients), degenerative scoliosis (15 patients), pseudarthrosis below long fusions (13 patients), and traumatic kyphosis (5 patients). Patients were analyzed clinically and radiographically and all complications were noted. Correction of coronal deformity and correction of fixed sagittal imbalance were measured by comparing preoperative and postoperative radiographic measurements. All patients completed the Zuckerman written questionnaire to assess patient's subjective clinical result.

Results: Twelve of 78 patients (15.3%) developed pseudarthrosis with broken implants; however only 5 of 78 (6.4%) nonunions occurred at the lumbosacral junction. Six of 78 patients (7.7%) required removal of the iliac screws for pain or painful prominence. Forty-two patients had one or more complications with an overall complication rate of 54%. Despite the overall complication and revision rate, 78% of patients reported good or excellent results with the Zuckerman questionnaire. Excellent correction of sagittal balance and coronal deformity was achieved. Average sagittal balance preoperatively was+10 and improved to an average of+2.5 postoperatively. Average major curve coronal plane deformity preoperatively was 61 degree and improved to an average of 29 degree postoperatively. There were no sacral fractures, sacral screw failures, or significant sacroiliac joint degeneration on follow-up radiographs.

Conclusions: In this series, nonunions continue to be a problem, with a rate of 15.3%, however only 6.4% of nonunions were at the lumbosacral junction. Complications specific to iliac screw placement were minimal. These difficult surgeries are known to be plagued with problems and our complication rate is consistent with what is present in the current literature. The use of iliac wing fixation seems to dramatically improve lumbosacral fusion rates with an acceptable complication rate; in addition there seems to be a protective effect in preventing sacral fractures, sacral screw failure, and sacroiliac arthritis.