Use of the S-hook for Pelvic Fixation in Rib-Based Treatment of Early-Onset Scoliosis: A Multicenter Study

Abstract

Study design: Retrospective review.

Objective: The purpose of this study was to evaluate how several preoperative variables affect the outcome using the rib-to-pelvis S-hook constructs of a rib-based distraction implant (Vertical Expandable Prosthetic Titanium Rib).

Summary of background data: Rib-to-pelvis fixation with S-hooks is one of the options for distal anchoring of rib-based distraction growing rod construct to control early-onset spinal deformity. Since the initial report, the indications of pelvic fixation with S-hooks have been extended and modified.

Methods: This is an institutional review board-approved retrospective study of patients who underwent rib-based growing rod system surgery-rib-to-pelvis construct with Dunn-McCarthy S-hook. Data evaluation included history, physical examination, preoperative and postoperative radiographs, surgical variables, and complications.

Results: Sixty-five patients were evaluated; 38 were male and 27 were female. Mean age at initial procedure was 71 months. The mean follow-up was 46 months. There was a statistically significant improvement of the immediate postoperative Cobb angle and the last follow-up Cobb angle (P < 0.0001). Fifty percent of the patients (32/65) had S-hook-related complications. The most common complication was sliding of the S-hook out of the iliac crest, followed by infection, neuropathic pain, distal migration of more than 2 cm, fracture of the hook, and bursitis. The complications were related to the preoperative ambulatory status, the use of end-to-end rod connectors, surgical time, and not positioning the hook over the central one-third of the iliac crest at the initial implantation.

Conclusion: The use of the S-hook as a pelvic attachment of the rib-based system is indicated in nonambulatory patients with progressive, early-onset scoliosis curve with a lack of adequate anchor at the lumbar spine. Several technical factors should be considered to reduce the complication rate.

Level of evidence: 3.