Full-time bracing versus hybrid bracing in adolescent idiopathic scoliosis: study protocol for a randomised controlled trial

BACKGROUND: Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional spinal deformity affecting 2-4% of adolescents. During the peripubertal stage, untreated AIS may progress rapidly and lead to adverse outcomes such as back pain and poor body image. Full-time bracing, such as the underarm brace (UAB), is indicated for skeletally immature patients with a Cobb angle greater than 20°. Nighttime lateral bending braces (LBB) aim to achieve overcorrection by positioning the patient in a supine bending position opposite to the curve convexity. Despite bracing, 20-30% of patients experience progression requiring surgery. In-brace correction (IBC) is a key determinant of bracing effectiveness. To enhance IBC, we propose a Hybrid Bracing Protocol (HyBP) combining daytime UAB and nighttime LBB. OBJECTIVE: The objective of this trial is to determine whether the Hybrid Bracing Protocol achieves greater in-brace correction (IBC) compared with the conventional bracing at 3 months and 18 months after brace initiation. This 18-month study represents the first phase, followed by a second phase assessing curve outcomes at brace completion and 2 years post-bracing. METHODS: This is a prospective, randomised, parallel-group trial comparing the Hybrid Bracing Protocol (HyBP) with conventional bracing for enhancing in-brace correction (IBC). Skeletally immature female patients with adolescent idiopathic scoliosis and a single thoracolumbar or lumbar curve newly prescribed for bracing will be randomly allocated to either the HyBP group or conventional brace group (CB group). DISCUSSION: To our knowledge, this will be the randomised trial to evaluate the potential synergistic effect of combining two different bracing designs within a hybrid protocol. If effective, this approach may improve bracing outcome, reduce curve progression, and decrease the need for surgical intervention. TRIAL REGISTRATION: ClinicalTrials.gov NCT07045337. Registered on July 9, 2025.