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 images of the lumbar spine in consecutive patients (n = 581) undergoing computed tomography 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 3 age groups (<50, 50-69, and ≥70). The influence of bilateral L5 spondylolysis (L5-lysis) and L5 vertebral slip on each lumbopelvic parameter, as well as 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 nonspondylolysis (nonlysis) patients. L5-lysis patients more frequently showed L5 vertebral slip than nonlysis patients, and a 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 the L5-S1 angle occurs frequently. The progression of vertebral slip was correlated with atrophy of psoas muscles, but not that of paraspinal extensor muscles.
Keywords: Alignment; CT; Computed tomography; Disk; Lumbar lordosis; Sacral slope; Spondylolysis.
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