[The involvement of the sacroiliac joints in rheumatoid arthritis. A retrospective radiographic study]

The frequency and type of involvement of the sacroiliac joints in rheumatoid arthritis (RA) is a controversial issue. In this study we compared sacroiliac plain radiographs of 120 RA patients and 106 age and sex-matched primary osteoarthritis (OA) patients. Nobody had a history of low back pain. On the basis of the radiologist's report, sacroiliac alterations were found in 24 (20.0%) RA patients (subchondral sclerosis in 20, joint space narrowing in 2, bone erosions in 1 and bone ankylosis in 1) and in 13 (12.3%) OA patients (subchondral sclerosis in all). Neither the frequency nor the radiographic pattern of alterations were significantly different between the two groups. We conclude that radiographic changes of the sacroiliac joints in RA are mostly of degenerative nature not differing from those found in a OA control population.