Psoriatic spondylitis: a clinical, radiological, and scintiscan survey.

Thirty-three per cent of patients with psoriatic spondyloarthropathy referred to a rheumatic disease unit were found to have radiological sacroiliitis. The majority of these patients had definite or probable spondylitis according to the New York criteria. Abnormal sacroiliac uptake of 99mTcPP on bone scan correlated well with the radiological finding of sacroiliitis. In addtion, eight patients with normal radiographs had an abnormal uptake of radionuclide over the sacroiliac joints, indicating sacroiliitis. Patients with sacroiliitis tended to have more severe psoriasis. Sacroiliitis occurred in association with all of the patterns of peripheral joint involvement which may occur in psoriatic arthritis. Although the HLA antigen B27 was present in only 21 percent of the total group and in 33 percent of those with sacroiliitis, 8 out of 10 with this antigen had sacroiliitis.