The detection of spinal pseudarthrosis in ankylosing spondylitis

Abstract

Spinal pseudarthrosis in ankylosing spondylitis can be difficult to detect radiologically. The value of bone radioscintigraphy in relation to radiological examination is assessed. Patterns of tracer uptake in the spine were recorded in 16 patients with established ankylosing spondylitis complicated by pseudarthrosis. Twenty such lesions were identified in 16 patients, mostly occurring at 1 level in a junctional region of the spine. Four patients had 2 lesions. Standard radiography failed to demonstrate this abnormality in 7 patients and in these tomography was required to confirm the scintigraphic findings. Bone scanning was much less accurate than conventional radiology in detecting the minor forms of marginal vertebral end plate destruction (spondylo-discitis). 99Tc-MDP [99mTc-methylenediphosphate] scanning may be a useful primary investigation for the detection of spinal pseudarthrosis in patients with chronic ankylosing spondylitis who suffer late onset back pain.