Radiographic joint space in rheumatoid acromioclavicular joints: a 15 yearprospective follow-up study in 74 patients

Objective. To evaluate radiographically the acromioclavicular joint space i n patients with long-term rheumatoid arthritis (RA). Methods. A cohort of 74 patients with RA was followed prospectively for 15 yr. At the end point, 148 shoulders were radiographed with a standard metho d. The acromioclavicular (AC) joint space was examined from the radiographs with a method developed previously for population studies; the joint space was measured at its superior and inferior border, and the average of the t wo measurements, the integral space, calculated. Results. Mean AC joint space in RA patients was 4.9 (S.D. 3.7), range 0-20. 5 mm; 6.2 mm (S.D. 5.1) in men and 4.5 mm (S.D. 3.0) in women. An AC joint space wider than 7 mm in men was found in 11 (31%) out of 36 joints and wid er than 6 mm in women in 17 (15%) out of 112 joints. Joint space widening w as associated (r = 0.87, 95% CI 0.82-0.90) with increasing destruction (Lar sen grading) of the joint and it seems to be an inevitable consequence of A C joint affection in RA. Joint space widening is more progressive on the ca udal side because of the nature of the erosive destruction. Degeneration wi th joint space narrowing was observed in 8 (11%) patients(11 joints, 7%; th ree bilateral). Conclusions. The largest value of the joint space may be used when evaluati ng rheumatoid AC joint space. In RA patients, a joint space of > 7 mm in me n and > 5 mm in women is a sign of destructive AC joint affection.