Bony overgrowths and abnormal calcifications about the spine.

The common phenomenon of osteophyte formation about the vertebral margins and on the vertebral bodies in certain instances connotes underlying disk degeneration. The classification and mechanism of formation of these bony excrescences are not totally clear in all instances, but there is frequent association with degenerative disk change. Distorted alignment of the spinal column as in scoliosis, and functional demands on the spine, play major roles in these abnormalities. The true degree of anatomic abnormality is greater than can be appreciated on the radiographs. Syndesmophytes are vertically orientated outgrowths of trabecular bone forming in the outer margins of the annulus fibrosus and related to repeated episodes of inflammation and repair. They are classically seen in ankylosing spondylitis and colonic spondyloarthropathy. Bulky paravertebral excrescences are more likely to be found in psoriatic arthritis and Reiter's syndrome. Other bony excrescences in the spine were also discussed. OPLL is a progressive disease that can result in severe radicular and myelopathic symptoms. Although OPLL appears to have an unexplained predilection for Asians, it affects all races. Classically diagnosed on lateral radiographs of the cervical spine, it is best imaged with CT. Proper evaluation of the extent of the entire ossified mass and its effect on the spinal cord is crucial in the planning of adequate therapy.