Complications of axial arthropathies.

Involvement of the cervical spine by rheumatoid arthritis may have severe consequences secondary to subluxation, erosive changes, and soft-tissue inflammation. Unfortunately, the severity of radiographic findings may not directly correlate with the occurrence of cervical myelopathy. MRI has emerged as a noninvasive method of assessing the condition of the spinal cord and thecal sac as well as more precisely defining the nature of inflammatory soft-tissue changes that may result in bony erosion and cord compression. Ankylosing spondylitis is an arthropathy that classically involves the axial skeleton. Complications include acute fracture and pseudarthroses of the spine. Rarely, the development of a cauda equina syndrome has been reported. In addition to classic erosive arthropathies affecting the axial skeleton, ossification of the posterior longitudinal ligament may be associated with the development of severe myelopathy. A recently described type of amyloidosis characterized by beta-2 microglobulin deposition has been reported in patients on long-term hemodialysis. Bony erosion is seen in the spine in these patients. A causal relationship between beta-2 microglobulin and hemodialysis spondylarthropathy has yet to be definitely established.