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elbow remains at the side while the arm is placed in external rotation. The subscapularis is imaged from the musculotendinous junction to the insertion on the lesser tuberosity of the humerus. Dynamic evaluation as the patient moves from internal to external rotation is helpful to evaluate dynamic biceps tendon subluxation or subcoracoid impingement and assess the integrity of the subscapularis tendon. To examine the supraspinatus tendon, the arm is extended posteriorly, and the palmar aspect of the hand can be placed against the superior aspect of the iliac wing with the elbow flexed and directed toward the midline (instruct the patient to place the hand in the ipsilateral back pocket). To scan the supraspinatus and infraspinatus tendons along their long axes, it is important to orient the transducer approximately 45° between the sagittal and coronal planes to obtain a longitudinal view. The transducer then should be moved anteriorly and © 2017 American Institute of Ultrasound in Medicine 14750 Sweitzer Ln, Suite 100 Laurel, MD 20707-5906 USA www.aium.org 6 posteriorly parallel to this imaging plane while continually adjusting to its angle to remain perpendicular to the investigated tendon. Short-axis views of the tendons should be obtained by rotating the transducer 90° to the long axis. The tendons are visualized by sweeping medially to the acromion and laterally to their insertions on the greater tuberosity of the humerus. When necessary, the more posterior aspect of the infraspinatus and teres minor tendons can be examined by placing the transducer at the level of the glenohumeral joint below the scapular spine while the forearm rests on the thigh with the hand supinated. Internal and external rotation of the arm is helpful to identify the infraspinatus muscle and tendon and to detect small joint effusions. To visualize the teres minor tendon, the medial edge of the transducer should be angled slightly inferiorly. The teres major tendon can also be identified in the short axis by placing the transducer in a longitudinal plane at the surgical neck of the humerus where it inserts and scanning medially along the inferior border of the scapula. Throughout the examination of the rotator cuff, the cuff should be compressed with the transducer to detect nonretracted tears. When evaluating for rotator cuff tears, comparison with the contralateral side may be useful. Dynamic evaluation of the rotator cuff also is useful in certain circumstances: for example, to evaluate the rotator cuff for impingement. Tear length (partial-thickness tear) or the degree of retraction of the cuff (full-thickness tear) should be measured on longitudinal views, and tear width should be measured on short-axis views. A partial-thickness tear should further be described as bursal, articular, or intrasubstance, and its thickness should be measured. It is also useful to measure the distance between the intra-articular portion of the biceps tendon and the anterior edge of the tear on short-axis views; most degenerative tears are located in the crescent of the cuff, approximately 15 mm from the intra-articular portion of the biceps tendon. 2 In patients with a rotator cuff tear, the supraspinatus, infraspinatus, and teres minor muscles should be examined for fatty infiltration and atrophy, as these findings are associated with a poorer postoperative outcome. Comparison with the contralateral rotator cuff muscles is often helpful in confirming muscle atrophy and fatty infiltration. Rotator cuff thickness and echogenicity should also be evaluated; a thick, hypoechoic cuff indicates tendinosis. © 2017 American Institute of Ultrasound in Medicine 14750 Sweitzer Ln, Suite 100 Laurel, MD 20707-5906 USA www.aium.org 7 During the rotator cuff examination, the subacromial-subdeltoid bursa should be examined for the presence of synovial hypertrophy. Power or color Doppler imaging should also be used to detect hyperemia. It is also important to evaluate the posterior glenohumeral joint for effusion, synovitis, or labral abnormalities. This can be accomplished by placing the transducer in a transverse plane at the level of the joint space. If symptoms warrant, the suprascapular notch and spinoglenoid notch also may be evaluated for a paralabral cyst. The acromioclavicular joint should be evaluated for arthritis, infection, or trauma by placing the transducer at the apex of the shoulder, over the acromion and distal clavicle. 3–5 Ultrasound is very useful in evaluating infants with glenohumeral dysplasia. These infants are examined in a decubitus position, and older children are examined seated. The shoulder is scanned from a posterior approach to evaluate the relationship between the humeral head and glenoid, as well as the shape of the posterior glenoid. Both static and dynamic images are obtained. The shoulder is scanned through the full range of internal to external rotation. Posterior subluxation is assessed visually and by measuring the α angle, which is the angle between the posterior margin of the scapula and the line drawn tangentially to the humeral head and posterior edge of the glenoid. The normal value of the α angle is 30° or less. The clavicle and proximal humerus are also evaluated for fracture. 6 B. Specifications for an Elbow Examination An elbow examination may be indicated to evaluate for synovial hypertrophy or synovitis, crystal deposition, loose bodies,
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