Abstract
BACKGROUND: Changes in coronal curve type and curve span may be linked to spinal and rib cage deformities. Therefore, it is crucial to comprehend the potential impact of these changes on brace treatment. This study aims to investigate the relationship between curve progression and change in coronal curve type and curve span in braced patients, and to compare the coronal balance and change in apical vertebral between patients with and without curve pattern change. METHODS: Two hundred seventeen patients who fulfilled the Scoliosis Research Society brace referral criteria were recruited. Radiographs at prebrace and brace weaning were assessed. Patients were classified into three groups based on the curve pattern at prebrace: major thoracic (MT), major lumbar (ML) and double major (DM). Change in coronal curve referred to curve of the greatest magnitude changes from thoracic to lumbar or vice versa. Change in curve span defined as change of at least two vertebral levels in the end vertebra of the curve. Change in apical vertebrae referred to change of at least one vertebral level. The association between coronal imbalance, major curve progression and regression, change in coronal curve type, change in curve span, change in apical vertebrae, and curve type were studied using Chi-square test. Multivariable logistic regression was used to predict curve progression at brace wean in each curve type. RESULTS: The major lumbar group exhibited a higher risk of coronal imbalance (Listing-MT: 5.6% vs ML: 37.7% vs DM: 23.5%, p < 0.001 and truncal shift-MT: 6.9% vs ML: 27.3% vs DM: 2.9%, p < 0.001) and changes in apical vertebrae (MT: 30.6% vs ML: 58.4% vs DM: 45.6%, p = 0.003). The double major group had a greater likelihood of experiencing changes in the coronal curve type (MT: 0% vs ML: 15.6% vs DM: 25%, p < 0.001) and major curve progression (MT: 23.6% vs ML: 22.1% vs DM: 52.9%, p < 0.001). In the major thoracic group, predictive factors for curve progression included being female, having poor brace compliance, and no change in curve span. However, no significant relationships were found for the major lumbar group. Patients with a larger prebrace major Cobb angle, larger thoracic kyphosis and poor brace compliance from double major group were more likely to experience curve progression. CONCLUSIONS: This study suggests that each curve type undergoes distinct changes during bracing. Future studies should consider the influence of curve type in study design and address the challenges associated with each type.