Radiographic Analysis of Newly Developed Degenerative Spondylolisthesis in a Mean Twelve-Year Prospective Study

Study Design. Prospective study of community-based female volunteers. Objective. To investigate the incidence of newly developed degenerative spondylolisthesis (DS) among those without baseline deformity, and to clarify radiographic characteristics and predictors of DS. Summary of Background Data. There has been limited number of prospective studies of DS. Our on-going cohort study of healthy volunteers enabled long-term observation of highly susceptible perimenopause female subjects. Methods. A final total of 142 female subjects without spondylolisthesis at baseline radiographs were included and followed up for more than 8 years. Standardized serial entire spine radiographs were used to measure spinopelvic alignment, including pelvic incidence (PI), vertebral inclination angle, disc height, vertebral size, and facet orientation. Results. The incidence of newly developed DS was 12.7%. Comparison between DS and non-DS subjects demonstrated that DS subjects had significantly greater baseline lumbar lordosis, PI, vertebral inclination angle, and smaller vertebral size. Exaggerated lumbopelvic alignment was more prominent in L3-DS than in L4-DS, and L4-DS was associated with the decrease in L4/5 disc height. Multivariate analysis revealed that PI, L4 vertebral inclination, adjusted vertebral size, and facet sagittalization were independent predictors of the development of DS. Conclusion. This was the first study to confirm the relationship of PI and the development of DS in a longterm prospective observation. Proposed pathogenetic differences might explain the fact that L4-DS is far more prevalent than L3-DS. The development of DS could be predicted by baseline lumbopelvic morphology among the highly susceptible perimenopause women.