Imaging Studies
Plain radiography
Plain radiography of the shoulder can be very helpful in the diagnosis of rotator cuff disease. Standard views should include a true anteroposterior (AP) view (in the plane of the scapula), a supraspinatus outlet view, and an axillary view.
The true AP view helps determine acromiohumeral distance, which is narrowed in association with rotator cuff tears. This view also identifies sclerosis and spurring of the acromion and reactive changes at the rotator cuff insertion site on the greater tuberosity, including sclerosis and cyst formation, all of which are associated with chronic tears.
The outlet view (a lateral radiograph in the scapular plane with the beam tilted 10° caudad) helps identify acromion shape and slope.
The axillary view helps identify the humeral head position in relation to the glenoid.
MRI
Magnetic resonance imaging (MRI) has replaced arthrography as the criterion standard for diagnosing injuries to the rotator cuff, as arthrography was found to be specific, but not sensitive, for the diagnosis of partial rotator cuff tears in adolescents. [26]
MRI is a noninvasive imaging modality that is extremely sensitive and specific. It can be used to detect the size, location, and characteristics of rotator cuff pathology.
In a rotator cuff tear, the tendon demonstrates a bright signal on T1-weighted images that increases significantly on T2-weighted images.
The increased signal on T2-weighted images is fluid that is filling the defect and helps to differentiate a frank tear from tendinosis.
MRI is a very costly technique that requires absolute lack of patient motion while the patient is being scanned.
A small percentage of patients are unable to complete the test secondary to pain or claustrophobia.
Ultrasonography
Ultrasonography may also be used to evaluate the rotator cuff. [27] This modality is inexpensive, convenient, and highly accurate in detecting full-thickness rotator cuff tears. A study by Saragaglia et al showed that in 48 patients who presented to the emergency department with acute shoulder injury, ultrasonography had an 82% positive predictive value for rotator cuff tear. [28]
Ultrasonography can be used to characterize the extent of the rotator cuff tear and to visualize biceps tendon dislocation.
One drawback to this modality is that it is extremely operator dependent, and the sensitivity and specificity of this test in detecting rotator cuff tears vary with the ultrasonographer's skill.
Other Tests
Electrodiagnostic testing
EMG and nerve conduction testing are helpful in the evaluation of possible suprascapular nerve impingement and involvement of the long thoracic, axillary, musculocutaneous, spinal accessory, and brachial plexus nerves and to rule out cervical radiculopathy as a cause of shoulder pain and weakness.
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Rotator cuff, normal anatomy.
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Rotator cuff tear, anterior view.
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The acromioclavicular arch and the subacromial bursa.
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Neer impingement test. The patient's arm is maximally elevated through forward flexion by the examiner, causing a jamming of the greater tuberosity against the anteroinferior acromion. Pain elicited with this maneuver indicates a positive test result for impingement.
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Hawkins test. The examiner forward flexes the arms to 90° and then forcibly internally rotates the shoulder. This movement pushes the supraspinatus tendon against the anterior surface of the coracoacromial ligament and coracoid process. Pain indicates a positive test result for supraspinatus tendonitis.
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Rotator cuff injury.
