Progressive degeneration of articular cartilage and intervertebral discs. An experimental study in transgenic mice bearing a type IX collagen mutation.

Transgenic mice expressing mutant alpha 1(IX) collagen were produced and found to develop progressive joint degeneration with age, as well as accelerated intervertebral disc degeneration. Radiological and histological studies showed that cervical and lumbar disc degeneration was more advanced in the transgenic mice than in control litter-mates. The changes included shrinkage or disappearance of the nucleus pulposus, and fissures in the annulus fibrosus which sometimes lead to herniation of disc material and slight osteophyte formation. These findings suggest that mutations of the type IX collagen may cause certain forms of degenerative disease in the spine as well as in joints.