Methodological exploration of stress-based finite element growth modeling for long-term brace treatment evaluation in adolescent idiopathic scoliosis.

To propose a stress-driven finite element growth prediction method for evaluating the long-term corrective potential of brace treatment in adolescent idiopathic scoliosis. CT data from an adolescent idiopathic scoliosis patient with Risser stage 4 were used to construct a patient-specific finite element model that included the vertebrae, intervertebral discs, posterior elements, ligaments, and ribs. Three-point corrective forces were applied under gravity and non-gravity conditions, and stress distributions were used to simulate differential vertebral growth. Model validity was confirmed by comparing simulated displacements with bending radiographs. Finite element simulations demonstrated effective in-brace correction under both gravity and non-gravity conditions, with main thoracic curve correction rates of 40.7% and 61.1%, respectively. The maximum displacement occurred at the rib corresponding to the apical vertebra, while peak normal stresses were concentrated at the T9–T10 and T10–T11 intervertebral discs, reaching 808.7 kPa under gravity and 3493.3 kPa under non-gravity conditions. Stress redistribution induced a reversal of convex–concave normal stress patterns within key thoracic and lumbar discs. Stress-driven growth simulations showed reduced vertebral wedging in most segments, with decreases in the three-dimensional height wedging index observed in the majority of vertebrae. The apical vertebra T8 showed the most pronounced improvement in coronal endplate tilt, whereas a mild increase in the global three-dimensional height wedging index was observed in several lumbar vertebrae, likely due to distal compensation and mechanical load redistribution. This study introduces a novel finite element method that emphasizes the prediction of long-term structural improvement under brace treatment. Beyond immediate correction, this approach provides a predictive biomechanical tool for individualized brace design and outcome evaluation.