Vertebral pseudoarthrosis associated with diffuse idiopathic skeletal hyperostosis.

Diffuse idiopathic skeletal hyperostosis is an ossifying diathesis that commonly affects the vertebral skeleton. Spinal ankylosis can occur, predisposing the spine to abnormal stresses and fracture. Fracture through an ankylosed segment with continued motion at the site of fracture can result in pseudoarthrosis. Pseudoarthrosis can also develop at the junction of the fused and mobile spine secondary to chronic abnormal stresses. This complication is manifest radiographically by single-level intervertebral disc space destruction, vertebral endplate erosions, marked vertebral sclerosis, and large osteophytes. The radiographic manifestations can mimic infective spondylitis or neuropathic changes.