Association between disc degeneration and degenerative spondylolisthesis? Pilot study

Objectives: The aim of this pilot study was to test the generally believed hypothesis that intervertebral disc degeneration is a prerequisite for degenerative spondylolisthesis (DS). Methods: This cross-sectional study was an ancillary project to the Framingham Study. A sample of 3529 participants aged 40-80 years had a CT scan performed to assess aortic calcification. 188 individuals were randomly enrolled in this study. The prevalence of intervertebral disc narrowing, facet joint osteoarthritis (FJOA) and DS were evaluated. We used the multiple logistic regressions to evaluate the association between DS as a dependent variable and FJOA, disc narrowing, age, sex and BMI as independent variables. Results: There were 23 individuals (24 spinal segments) affected by DS (15 female, 8 male), mean age 62.0 ± 6.8 years. In segments with DS, FJOA was observed and rated "severe" at 20 (83.3%) segments, "moderate" at 3 (12.5%) levels, and "mild" at 1 (4.2%) level. Intervertebral disc height was normal in 6 (25.0%), slightly decreased in 6 (25.0%), moderately decreased in 5 (20.8%) and severely decreased in 7 (29.2%) of the segments. Three (12.5%) segments with DS had severe FJOA but no apparent disc degeneration. In 9 (37.5%) segments with DS we found no or mild disc degeneration and severe FJOA. In a multiple regression analysis age, sex and FJOA, but not disc narrowing, showed significant associations with DS. Conclusions: The results of our study did not support the theory that disc degeneration necessarily precedes vertebral subluxation in DS.