LAUSR

BACKGROUND To elucidate the influence of spondylolysis on age-related lumbar degenerative changes, age-specific lumbopelvic alignment in patients with or without spondylolysis was examined. METHODS Sagittal reconstructed computed tomography (CT) images of the lumbar spine in consecutive patients (n=581) undergoing CT scans of abdominal or lumbar regions for reasons other than low back disorders were obtained; lumbar lordosis (LL), L5-S1 angle, and sacral slope (SS) were measured. Lumbopelvic parameters in patients with or without spondylolysis were evaluated in three age groups (<50, 50-69, and ≥70). The influence of bilateral L5 spondylolysis (L5-lysis) and L5 vertebral slip on each lumbopelvic parameter, and correlation between cross-sectional area (CSA) of paraspinal muscles and the degree of vertebral slip were examined by multiple regression analysis. RESULTS Patients with bilateral spondylolysis showed greater LL and SS than patients without spondylolysis. When analyzing the influence of L5-lysis, only elderly patients (≥70) with L5-lysis showed significantly greater LL and SS than non-spondylolysis (non-lysis) patients. L5-lysis patients more frequently showed L5 vertebral slip than non-lysis patients and smaller L5-S1 angle was observed when L5 vertebral slip accompanied L5-lysis. The degree of vertebral slip was significantly correlated with CSA of psoas muscles, but not with CSA of paraspinal extensor muscles. CONCLUSIONS When patients have L5-lysis, lumbar lordosis and pelvic anteversion occurred age-dependently. In elderly patients with L5-lysis, L5 vertebral slip with decrease of L5-S1 angle frequently occurs. The progression of vertebral slip was correlated with atrophy of psoas muscles, but not that of paraspinal extensor muscles.