Growth pattern of lumbar vertebrae and lumbosacral alignment during adolescence: a longitudinal study

Purpose Although adolescence is a critical period for lumbar spine injuries, the developmental link between vertebral morphology and lumbosacral alignment remains unclear. We determined the timing of peak growth velocity in vertebral parameters (L1–L5) and their relationship with lumbar lordosis (LL) and sacral slope (SS) in male junior high school athletes. Methods This longitudinal study of 134 male junior high school soccer players included 412 MRI assessments obtained semiannually from the first to third year. Vertebral morphology (anterior and posterior heights, superior and inferior widths) of L1–L5 was evaluated on midsagittal MR images. LL and SS were measured as standard alignment angles. Growth age was defined relative to age at peak height velocity (APHV). Generalized additive mixed models identified nonlinear growth trajectories. Random-effects panel regression was used to examine associations between summed morphology measures and alignment. Results Vertebral heights and widths exhibited significant nonlinear growth (all q < 0.05), with height parameters peaking ~ 2 years after APHV then decelerating. SS peaked around APHV whereas LL remained stable (p < 0.001, q < 0.001 for SS; LL: edf = 2.50, F = 0.879, p = 0.250, q = 0.250). In panel models, summed anterior height was positively associated with LL, whereas summed posterior height was negatively associated with LL. Conclusion Lumbar vertebral bodies grow nonlinearly in male adolescent athletes, with height plateauing after PHV and widths continuing to increase. SS changes around growth peak while LL remains stable, with anterior–posterior height balance influencing lordotic alignment.