Prof. Guangzhou Sport university Guangzhou, Guangdong, China (People's Republic)
Objectives : This study aimed to identify biomechanical factors affecting proximal thoracic (PT) apical wedging and disc-endplate adaptation during Chêneau bracing, and to determine how modifiable predictors can guide orthotic strategies for multiple curves—optimizing main thoracic (MT) correction while minimizing compensatory biomechanical overload.
Design: We conducted a propensity-matched cohort study using prospectively enrolled patients from the Guangdong Provincial Center for Adolescent Scoliosis (2016–2024). Among 1,024 consecutively screened patients with adolescent idiopathic scoliosis (AIS), 148 Lenke type II cases (14.5%) were identified through dual-blinded adjudication. After excluding individuals with congenital or neurological disorders (n=21), prior treatment (n=12), skeletal maturity (Risser ≥4, n=15), or insufficient 12-month follow-up (n=24), 97 bracing-naïve adolescents (82% female; mean age 12.8±1.9 years) were included, representing 65.5% of eligible candidates. The study was powered at 83% (α=0.05) to detect apical wedging differences of ≥3°, based on SRS clinical thresholds.
Results: In matched pairs (n=74), correction was significantly greater for MT (Δ32.8%, 95% CI 25.4–40.2, P=0.003) and lumbar curves (Δ41.1%, 95% CI 33.7–48.5, P< 0.001) compared to PT curves. Younger patients (≤12 years, n=32) demonstrated better PT correction (Δ14.2%, 95% CI 9.8–18.6, P=0.018). Convex disc height decreased by 1.83±0.45 mm (P< 0.001), whereas the concave side remained stable. Baseline PT Cobb angle (β=1.171 per degree, P< 0.001) and lumbar correction rate (β=-0.563 per 10% change, P=0.018) independently predicted PT adaptation, with a moderating effect of age (β=-0.15 per year, P=0.018).
Conclusion: Chêneau bracing exerts segment-specific biomechanical effects, providing strong correction in MT and lumbar curves but showing relative vulnerability in the PT region, where correction inversely correlates with lumbar correction efficiency. These findings support tailored monitoring protocols for the proximal thoracic curve and age-adjusted corrective thresholds in the management of multicurve AIS.
