Pathological changes in the cartilaginous plates in relation to intervertebral disc lesions.

Three hundred sixty-eight intervertebral discs (T11/12-L5/S1) were obtained at autopsy from 61 individuals (36 male, 25 female) ranging from 25 to 85 years of age, and subsequently examined histopathologically as sagittal-sectioned specimens with special reference to the cartilaginous plates. The numbers of cartilaginous foci found in fissured and ruptured regions of the plates were found to increase with age, and were considered to represent a restoration mechanism. Measurement of the cartilaginous plate/intervertebral disc antero-posterior length ratio showed a decrease with age in intervertebral discs from the same spinal level. Therefore, cartilage cell proliferation in the vertebral body rim was found following rupture of the outer layer of the annulus fibrosus and was thought to be one of the causes of spur formation in spondylosis deformans. When the changes in a cartilaginous plate with aging were accompanied by destructive processes of the vertebrae such as osteoporosis or metastatic cancer, an increase in the height of the disc, or ballooning, developed. On the other hand, when degeneration of the intervertebral disc increased and the nucleus pulposus collapsed, the height of the disc decreased. Thus, although the cartilaginous plate exhibits a restoration mechanism, degeneration with age progresses, resulting in various disc lesions.