Spondyloarthropathies: Laboratory and Radiographic Evaluation

Conventional plain radiography of the pelvis is a good screening tool for evaluation of sacroiliac joints in patients with inflammatory back pain. In the early stages of the evolution of syndesmophytes, there is inflammation of the superficial layers of the annulus fibrosus with subsequent reactive sclerosis and erosion of the adjacent corners of the vertebral bodies (called "shiny corners") (Figure 1).

Figure 1.
Radiograph of the lumbar spine in a patient with ankylosing spondylitis showing
reactive sclerosis and erosions at the corners of the vertebral bodies, or "shiny corners"(arrow).

This combination of destructive osteitis and repair leads to "squaring" of the vertebral bodies. The inflammatory process is associated with gradual ossification of the annulus fibrosus and eventual "bridging" between vertebrae by syndesmophytes (Figure 2). This may ultimately result in a virtually complete fusion of the vertebral column, resulting in the "bamboo spine" (Figure 3). Bony erosion and osteitis at sites of osseous attachment of tendons and ligaments are common, particularly at the calcaneus, ischial tuberosities, iliac crest, femoral trochanters, and spinous processes of vertebrae.

Figure 2.
Radiograph of the lumbar spine in a patient with ankylosing spondylitis showing
syndesmophyte formation including bridging (arrow) due to ossification of the annulus fibrosus.

Figure 3.
Radiograph of the lumbar spine in a patient with late-stage ankylosing spondylitis
showing extensive syndesmophyte formation with bridging ossification of the annulus fibrosus ("bamboo spine").

Cleveland Clinic Journal of Medicine
Volume 71, Number 3, March 2004

This paper discusses therapies that are experimental or are not approved by the U.S. Food and Drug Administration for use under discussion.