Ankylosing spondylitis complicated by trauma: MR findings correlated with plain radiographs and CT

Four patients with ankylosing spondylitis sustained a traumatic spinal injury. In three cases, pseudoarthrosis developed at the discovertebral junction, while involvement of the neural arch occurred in the fourth. Although the diagnosis of ankylosing spondylitis was readily established on plain radiographs, magnetic resonance more effectively identified the complicating injury and in two cases demonstrated the presence of cord compression. Computed tomography was also contributory in delineating bony and ligamentous abnormalities of the neural arch.