Intervertebral disk calcification associated with spine fusion.

Intervertebral disk calcification and spine fusion were observed in patients with Klippel-Feil syndrome, myositis ossificans progressive, juvenile rheumatoid arthritis, ankylosing spondylitis, and surgical spine fusion. The fusion appears to come first, leading to calcification. This suggests that fusion prevents the normal mechanical stresses within the disk, leading to premature degenerative changes and calcification of the nucleus pulposus.