The relationship between cartilage end-plate calcification and disc degeneration: an experimental study.

OBJECTIVE: To study the relationship between cartilage end-plate calcification and intervertebral disc degeneration.
METHODS: An experimental model of cervical disc degeneration in rabbits was established by resection of the cervical supraspinous and interspinous ligaments and detachment of the posterior paravertebral muscles from the cervical vertebrae. Mechanical instability in the cervical spine elicited by this surgical intervention accelerated the process of intervertebral disc degeneration. The extent of intervertebral disc degeneration was graded in morphologically, and the thicknesses of the calcified layer and the uncalcified layer of the cartilage end-plate were measured in each degenerated cervical disc.
RESULTS: In less severely degenerative cervical discs, the morphology of the cartilage end-plate showed nearly normal construction, and the tidemark was clear. In severely degenerative discs, the matrix and cells showed fibrosis, the tidemark advanced, and the calcified cartilage thickened. There exists a positive correlation between the thickness of the calcified layer of the cartilage end-plate and the degree of cervical disc degeneration.
CONCLUSION: The calcification of the cartilage end-plate is the key factor that initiates and promotes cervical disc degeneration.