Acromioclavicular joint fluid: determination of clinical significance with MR imaging.

PURPOSE: To determine the clinical significance of fluid in the acromioclavicular (AC) joint. MATERIALS AND METHODS: A total of 108 patients with clinical shoulder problems and 16 volunteers underwent MR imaging with a 1.5-T unit. Coronal T1- and T2-weighted images were evaluated for the presence of AC joint fluid, glenohumeral joint fluid, and AC joint osteophytes. Medical records were reviewed for the presence of clinical signs and symptoms. RESULTS: AC joint fluid was commonly seen in the patients (67%) but was rare in the volunteers (12%). The presence of AC joint fluid was associated with advancing patient age, presence of osteophytes, and fluid in the glenohumeral joint. AC joint fluid was not associated with focal tenderness, prior corticosteroid injections, history of trauma, findings of impingement, evidence of rotator cuff tear on MR images, or gender. CONCLUSION: AC joint fluid appears to be an asymptomatic manifestation of osteoarthritis.