Incidence of acromioclavicular joint involvement in rheumatoid arthritis: A 15 year endpoint study

Objective, To evaluate the incidence of involvement and nature of destructi on of acromioclavicular joints (AC) in a prospectively followed cohort of 7 4 patients with rheumatoid factor positive and erosive rheumatoid arthritis (RA). Methods. At the 15 year followup, radiographs of 148 AC joints were evaluat ed, and the grade of destruction was assessed by the Larsen method. Results. No surgical procedures had been performed on the AC joints. Rheuma toid involvement (Larsen Grade greater than or equal to 2) was observed in 87/148 (59%) of the AC joints in 50/74 (68%) patients: 37 bilaterally and 1 3 unilaterally. Incidence of mild erosions (Larsen Grade 2) was 39%, and of severe (Larsen 3-5) 20%. Erosions were most often observed on the inferior edge of the clavicular joint margin. Degenerative features without rheumat oid changes were present in 11 joints. Larsen score (0-100) of peripheral j oints correlated well with the AC joint Larsen Grade in both sides: right, r = 0.56 (95% CI 0.38 to 0.70), left, r = 0.49 (95% CI 0.30 to 0.65). Conclusion, After 15 years two-thirds of the patients with RA showed involv ement of the AC joints. Erosions were located most often on the inferior ma rgin of the joint.