Impact of direct vertebral body derotation on rib prominence: Are preoperative factors predictive of changes in rib prominence?

STUDY DESIGN.: Multicenter retrospective review of prospectively collected data. OBJECTIVE.: To determine the extent of rib deformity correction that can be expected with direct vertebral body derotation (DVBD) and investigate factors that may correlate with improved rib deformity correction. SUMMARY OF BACKGROUND DATA.: DVBD is a powerful tool in the surgical correction of axial rotation in adolescent idiopathic scoliosis. The application of DVBD has decreased the use of thoracoplasty for cosmetic rib deformity correction, but the outcomes of DVBD without adjuvant thoracoplasty have not been well defined. METHODS.: A multicenter database was retrospectively queried to identify patients with adolescent idiopathic scoliosis who underwent posterior spinal fusion with at least 2 years of follow-up and Lenke type 1 to 3 curves. All patients had undergone DVBD maneuvers during their surgery, and patients having undergone concurrent thoracoplasty were excluded from the study. The absolute change and percentage change from preoperative inclinometer readings were correlated with preoperative clinical and radiographic data. RESULTS.: A total of 148 patients fulfilled the inclusion criteria. The mean age was 14.7 ± 2.1 years with a mean primary thoracic curve of 55.3° ± 9.3°. The mean preoperative inclinometer reading was 14.8° ± 4.5°, which reduced to 7.5° ± 4.0° postoperatively. Patients had a mean improvement of 54% ± 29% in rib prominence using DVBD. We attempted to correlate 23 of the most commonly used preoperative clinical, radiographic, and operative measures with postoperative inclinometer improvement. Interestingly, none correlated with rib deformity correction, including preoperative rib deformity (P = 0.16), thoracic curve flexibility (P = 0.71), presence of osteotomies (P = 0.60), and thoracic curve magnitude (P = 0.78). CONCLUSION.: Utilizing DVBD, the surgeon can expect approximately 50% reduction in the rib deformity as assessed by inclinometer. This is irrespective of preoperative inclinometer measures, thoracic curve flexibility, and vertebral body rotation on standing and bending radiographs.