Study Design. A retrospective longitudinal observational study using baseline and follow-up magnetic resonance imaging (MRI).
Objective. To study the natural history of disc degeneration, focusing on the significance of changes affecting the individual components of the intervertebral disc.
Summary of Background Data. The natural history of the degenerative disc disease is poorly understood. Focusing on the relative prevalence, temporal evolution, and interactions of pathology in the anulus fibrosus, nucleus pulposus, and the end plates can help in better understanding of this process.
Methods. MRIs of the lumbar spine in 63 patients, obtained at a mean interval of 30 months, were evaluated independently by two neuroradiologists to assess the temporal evolution of degeneration changes in 378 discs between T12 through S1 segments. In addition, a direct side-by-side comparison of two studies was also performed. Statistical analysis was performed to assess the association between the degeneration of individual disc components and to find the predictors of future degeneration.
Results. Radial anular tears and end plate defects were associated with worse nuclear degeneration at the time of the initial study. Both end plate defects and nuclear degeneration were rare in the absence of radial tears. Multiple nominal logistic regression analysis showed that radial tears and herniation at the time of the initial study, along with the duration between the two imaging studies were the significant predictors of worsening nuclear degeneration. Age, sex, and the segmental disc level did not show any significant association with temporal progression of nuclear degeneration.
Conclusion. Radial tears and herniation are significant predictors of progressive nuclear degeneration, which was not seen in the absence of radial tears. End plate defects also frequently occur before nuclear degeneration but rarely in the absence of anular tears.