Impact of Rotation Correction after Brace Treatment on Prognosis in Adolescent Idiopathic Scoliosis

Study Design: Level 4 retrospective review. Purpose: Brace treatment is the standard nonoperative treatment for adolescent idiopathic scoliosis (AIS). Rotation correction is also important, because AIS involves a rotation deformity. The purpose of this study was to evaluate the impact of rotation correction after Osaka Medical College (OMC) brace treatment on clinical outcomes in AIS. Overview of Literature: Brace treatment has a significant effect on the progression of AIS. However, few reports have examined rotation correction after brace treatment. Methods: A total of 46 patients who wore the OMC brace were retrospectively reviewed. The curve magnitude was determined according to the Cobb method, and the rotation angle of the apical vertebrae was measured by the modified Nash-Moe method. Based on the difference in the rotation angle before and after the initial brace treatment, patients were divided into two groups. Group A (n=33) was defined as no change or improvement of the rotation angle; group B (n=13) was defined as deterioration of the rotation angle. If the patients had curve or rotation progression of 5 degrees or more at skeletal maturity, or had undergone surgery, the treatment was considered a failure. Results: Differences of rotation angle between before and after the initial brace treatment were 2 degrees +/- 2 degrees in group A and -3 degrees +/- 2 degrees in group B (p<0.001). The rates of treatment failure were 42% in group A and 77% in group B (p<0.05). This study included 25 patients with Lenke type 1 (54%). Group A (24%) with Lenke type 1 also had a significantly better success rate of brace treatment than group B (75%) (p<0.05). Conclusions: Insufficient rotation correction increased brace treatment failure. Better rotation correction resulted in a higher success rate of brace treatment in patients with Lenke type 1.