Influence of scoliosis severity on thoracolumbar biomechanical properties: a finite element analysis-based study.

OBJECTIVE: Using finite element analysis, this study investigated the influence of moderate and severe scoliosis on the biomechanical environment of the thoracolumbar spine under simulated gravitational loading in a standard standing posture. Focusing on spinal deformation, internal stress distribution, and the mechanical response of intervertebral discs, it aimed to provide a mechanical basis for understanding the mechanism of curve progression and a rationale for employing clinical treatment strategies. METHODS: Three-dimensional finite element models of the T1-L5 spinal segments were developed based on computed tomography data: one normal model, one with moderate idiopathic scoliosis, and one with severe idiopathic scoliosis. The models included vertebrae, intervertebral discs, and ligaments, all assigned realistic material properties. Mechanical behavior under simulated standing conditions. RESULTS: Compared with the normal model, the scoliosis models exhibited extremely uneven stress distributions. The peak element Von-Mises stress at the apical vertebra of the severe scoliosis model reached 2.28 MPa, which was 2.1 times that of the normal spine and 1.4 times that of the moderate model. Meanwhile, the average nodal stress on the concave cortical surface of the apical vertebra was 4.204 MPa, presenting significant asymmetric mechanical distribution. The annulus fibrosus strain showed severe asymmetry in the scoliosis models, which was more pronounced in the severe model. The results demonstrated a clear dose-response relationship between scoliosis severity and deterioration of the mechanical environment. CONCLUSION: The severity of scoliosis significantly alters the biomechanical behavior of the spine under gravitational load. These findings underscore the importance of considering mechanical factors in the treatment of scoliosis and provide a theoretical reference for the optimization of future corrective devices and surgical planning.