Sacroiliitis detected by bone scintiscanning: a clinical, radiological, and scintigraphic follow-up study.

Twenty-four patients had abnormal sacroiliac joints detected by quantitative sacroiliac scintigraphy but no radiological evidence of sacroiliitis on original investigation. We studied them again after intervals of 12 to 36 months. Four patients developed radiological change. Two young, HLA B27-positive men had undoubted ankylosing spondylitis, and a young woman had possible ankylosing spondylitis. A middle-aged man had changes that could be attributed to post-traumatic osteoarthrosis. Of the remaining 20 cases 15 had symptoms and signs suggestive of inflammatory disease of the axial skeleton (and peripheral arthropathy in 5 cases). The sexes were affected equally (8 females, 7 males), and only 2 of the 15 were B27-positive. The response to anti-inflammatory medication was generally good to excellent, and scintiscans tended to improve. Of the remaining 5 patients, 3 had mechanical or traumatic problems, and in 2 there was no explanation for the abnormal sacroiliac scintiscan. We conclude that quantitative sacroiliac scintigraphy may detect ankylosing spondylitis prior to the develpment of radiological change and that it can identify an organic basis for backache in patients with a spondylitis-like syndrome. The clinical circumstances must be taken into account, as scintigraphic abnormalities are not diagnostic of any specific disease entity.