Rheumatoid arthritis (RA) is a systemic autoimmune disease that has a great impact on different joints, may result in their destruction and loss of function. Although the shoulder is affected in a large portion of patients with RA, it does not receive much attention during the follow up of RA. The precise diagnosis of shoulder pain in RA is a clinical challenge and benefits from a reliable imaging modality to detect its exact origin.
To determine the diagnostic accuracy of ultrasound (US) in detecting shoulder joint pathologies in RA, considering magnetic resonance imaging (MRI) as the gold standard.
This cross-sectional, observational study was carried out on 30 RA patients complaining of unilateral or bilateral shoulder pain. Patients were subjected to history taking, clinical shoulder examination, plain X-ray, US examination following a standardized protocol, and MRI. The results were correlated with each other.
In comparison with the MRI findings, US showed high accuracy in terms of sensitivity (Sn) and specificity (Sp) in supraspinatus tendinopathy (Sn 96.6%; Sp 93.3%), biceps tenosynovitis (Sn 87.5%; Sp 97.6%), subacromial-subdeltoid bursitis (Sn 72.7%; Sp 95.7%), humeral erosions (Sn 90.5%; Sp 97.3%), and acromioclavicular osteoarthritis (Sn 85.7%; Sp 95.7%). In terms of reliability, the agreement between US and MRI was almost perfect (κ = .9, P < .001).
US may have a role as the initial imaging modality in RA patients with shoulder pain, as it is highly sensitive and specific in detecting different pathological abnormalities of the shoulder.