US of the shoulder: rotator cuff and non-rotator cuff disorders.

Ultrasonography (US) has been shown to be an effective imaging modality in the evaluation of both rotator cuff and non-rotator cuff disorders, usually serving in a complementary role to magnetic resonance imaging of the shoulder. US technique for shoulder examination depends on patient positioning, scanning protocol for every tendon and anatomic part, and dynamic imaging. The primary US signs for rotator cuff supraspinatus tendon tears are tendon nonvisualization for complete tears, focal tendon defect for full-thickness tears, a hypoechoic defect of the articular side of the tendon for an articular-side partial-thickness tear, and flattening of the bursal surface of the tendon for a bursal-side partial-thickness tear. Secondary US signs such as cortical irregularity of the greater tuberosity and joint and subacromial-subdeltoid bursal fluid are helpful when correlated with the primary signs. Tendon degeneration, tendinosis, and intrasubstance tear are demonstrated as internal heterogeneity. Long-head biceps tendon abnormalities include instability, acute or chronic tear, and tendinosis. The acromioclavicular joint is assessed for dislocation, fluid collection, cysts, and bone erosions. Other non-rotator cuff disorders include synovial disorders such as adhesive capsulitis and synovial osteochondromatosis; degenerative disorders such as osteoarthritis, amyloid arthropathy, hemarthrosis, and chondrocalcinosis; infectious disorders such as septic arthritis and bursitis; and space-occupying lesions.