Spinal movements in ankylosing spondylitis and the effect of treatment.

Fourteen male patients with ankylosing spondylitis, admitted for a 2-week period of inpatient treatment, had their spinal mobility assessed on admission and at the end of treatment by clinical measures and a three-dimensional radiographic technique. The patients were given injections of low-dose corticotrophin (ACTH) or placebo under a double-blind protocol. Initially all the patients had restricted movements compared with normal. After treatment all showed some improvement of mobility but no additional benefit accrued from ACTH. Clinical measures of mobility must be interpreted with care as the changes in these measurements were not closely reflected in the lumbar movements measured radiographically. Changes seen in plain radiographs were of little predictive value for improvements in mobility.