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 long-term 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.