Age-Specific Characteristics of Lumbopelvic Alignment in Patients with Spondylolysis: How Bilateral L5 Spondylolysis Influences Lumbopelvic Alignment During the Aging Process

Abstract

To elucidate the influence of spondylolysis on age-related lumbar degenerative changes, age-specific lumbopelvic alignment in patients with or without spondylolysis was examined. 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. 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. 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.