Improvement of Cobb angle and apical vertebral translation at brace application predicts brace treatment outcomes in adolescent idiopathic scoliosis.

PURPOSE: Various risk factors for curve progression during brace treatment in adolescents with idiopathic scoliosis (AIS) have been identified. However, curve-type-specific risk factors remain unclear. We aimed to identify risk factors for curve progression by curve type.

METHODS

At our hospital, we analyzed 211 patients with AIS (200 females, 11 males). X-rays were obtained before and immediately after brace application. Patients were categorized into those requiring surgery during follow-up (Surgery group) and those avoiding surgery (Avoidance group). Univariate and multivariate analyses identified risk factors for curve progression. Subgroup analysis was performed based on curve type.

RESULTS

Among all cases, 163 (77.3%) avoided surgery. In the univariate analysis, the Surgery group was significantly younger (p = 0.008), had a lower BMI (p < 0.001), a lower TOCI grade (p < 0.001), a lower Risser classification (p < 0.001), included more premenarcheal individuals (p < 0.001), had larger pre- and post-brace Cobb angles (p < 0.001), and fewer thoracolumbar/lumbar curves (p = 0.002) than the Avoidance group. Multivariate analysis showed that a lower TOCI grade (p = 0.005), thoracic curve type (p < 0.001), a larger post-brace Cobb angle (p = 0.001), and greater post-brace apical vertebral translation (AVT) (p = 0.006) were significant risk factors for requiring surgery. In both thoracic (N = 101) and thoracolumbar/lumbar curves (N = 110), the Surgery group had significantly larger pre- and post-brace Cobb angles (p < 0.001/p < 0.001 and p = 0.005/p < 0.001, respectively), and larger pre- and post-brace AVT (p = 0.049/p = 0.004 and p < 0.001/p < 0.001) than the Avoidance group.

CONCLUSION

In both thoracic and thoracolumbar/lumbar curves, reduction in the Cobb angle and AVT at the time of brace application is crucial for successful AIS management.