Spinal pseudoarthrosis complicating ankylosing spondylitis: a report of two patients.

Two middle-aged men with long-standing ankylosing spondylitis presented with recurrence of back symptoms after minor traumas. Clinical and radiographic findings were suggestive of spinal pseudoarthrosis at the L2/L3 and T11/T12 level, respectively, but the possibility of infectious spondylitis remained a concern. On granulocyte scintigraphy, the affected regions were distinguished by showing decreased activity. Magnetic resonance imaging clearly demonstrated the extent of the lesions and, in one of the patients, revealed spinal canal compression, which necessitated surgical treatment. The other patient gradually improved on conservative therapy.