Objective: To evaluate the sites of inflammatory process in the shoulders of patients with polymyalgia rheumatica (PMR) using fat suppressed magnetic resonance imaging (MRI).
Methods: Six consecutive, untreated new patients with PMR were investigated. Five patients with early rheumatoid arthritis (RA) and 4 patients with early psoriatic arthritis (PsA) with bilateral shoulder symptoms served as a control group. Bilateral shoulder fat-suppressed MRI sequences were performed in all patients and controls. We evaluated the presence of joint synovitis, bursitis, tenosynovitis, and bone and soft tissue edema.
Results: Bilateral subacromial/subdeltoid bursitis was found in all patients with PMR, in 1/5 (20%) patients with RA (p < 0.05), and in none with PsA (p < 0.02). Glenohumeral synovitis was present in all case and controls. Biceps tenosynovitis was observed in 4/6 (67%) patients with PMR, in 4/5 (80%) with RA (not significant, NS), and in all 4 patients with PsA (NS). No evidence of bone edema adjacent to the joint capsule and entheseal insertions or in the soft tissues was present in either cases or controls.
Conclusion: The absence of extracapsular abnormalities in the early shoulder disease of PMR does not confirm the hypothesis of a capsular-based disorder.