Masaru Itose

Lumbar lordosis influences load transmission in the lumbar spine, but its effects on stress in the anterior cortical bone of the vertebral bodies remain unclear. This study investigated how lumbar lordosis angle (LL) affects vertebral stress. A finite element model from T12 to the sacrum was constructed from computed tomography images of a cadaver from a 66-year-old male donor. Three models with identical bone geometry and material properties but LL values of 50°, 30°, and 15° were analyzed under a 300 N compressive load and the same load combined with a 5 N·m flexion moment. Mean von Mises stress and the 95th percentile of von Mises stress were evaluated in the anterior cortical bone of L1–L5, and vertebral-level distributions were normalized to L1. Under both loading conditions, the LL15° model showed higher von Mises stress than the LL50° and LL30° models at all vertebral levels. Adding the flexion moment further increased stress in all models. Normalized stress was lowest at L3 in the LL50° and LL30° models, whereas values in the LL15° model remained relatively close to L1 across L2–L5. These findings suggest that models with lower LL exhibit higher anterior cortical bone stress and altered vertebral-level stress distributions.