DOI: 10.1148/rg.256045203
RadioGraphics 2005;25:1591-1607
© RSNA, 2005
Rotator Cuff Tears: Clinical, Radiographic, and US Findings1
Josh B. Moosikasuwan, MD,
Theodore T. Miller, MD and
Brian J. Burke, MD
1 From the Department of Radiology, North Shore University Hospital, 825 Northern Blvd, Great Neck, NY 11021. Presented as an education exhibit at the 2003 RSNA Annual Meeting. Received November 16, 2004; revision requested January 4, 2005, and received January 28; accepted January 31. All authors have no financial relationships to disclose.
Address correspondence to T.T.M. (e-mail: tmiller{at}nshs.edu).
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Abstract
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Rotator cuff tears are a common cause of shoulder pain. Clinical and radiographic findings can suggest the presence of a rotator cuff tear. The most sensitive clinical findings are impingement and the "arc of pain" sign. Radiographic findings are usually normal in the acute setting, although the "active abduction" view may show decreased acromiohumeral distance. In more chronic cases, an outlet view may show decreased opacity and decreased size of the supraspinatus muscle due to atrophy. In late cases, the humeral head may become subluxated superiorly, and secondary degenerative arthritis of the glenohumeral joint may ensue. Ultrasonography (US), with over 90% sensitivity and specificity, can help confirm the diagnosis in clinically or radiographically equivocal cases. US can also reveal the presence of other abnormalities that may mimic rotator cuff tear at clinical examination, including tendinosis, calcific tendinitis, subacromial subdeltoid bursitis, greater tuberosity fracture, and adhesive capsulitis.
© RSNA, 2005
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LEARNING OBJECTIVES
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After reading this article and taking the test, the reader will be able to:
- Discuss the most useful clinical and radiologic tests for rotator cuff tears.
- Describe US assessment for rotator cuff tears.
- Develop a differential diagnosis for shoulder pain and identify clinical mimics of rotator cuff tears.
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Introduction
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Crass et al (1) and Middleton et al (2) in 1984 were the first to describe ultrasonographic (US) evaluation for rotator cuff tears, and US has proved to be as accurate as magnetic resonance (MR) imaging in the detection of supraspinatus tendon tears. In a recent study comparing US with MR imaging and using arthroscopy as the standard of reference, Teefey et al (3) demonstrated an overall accuracy of 87% for both modalities in correctly identifying partial- and full-thickness rotator cuff tears as well as the absence of such tears. In that study, US helped correctly identify 45 of 46 full-thickness tears and 13 of 19 partial-thickness tears, whereas MR imaging helped correctly identify all 46 full-thickness tears and 12 of 19 partial-thickness tears. The reported accuracy, sensitivity, and specificity of US in the detection of any tear, whether partial or full thickness, are all greater than 90% (3–5).
However, even before advanced imaging (eg, MR imaging, US) is performed, the diagnosis of rotator cuff tear can be suggested at clinical examination (6–9) and with radiography of the shoulder. In this article, we review the clinical, radiographic, and US evaluation of rotator cuff tears with an emphasis on US technique and the interpretation of US findings. We also discuss and illustrate a variety of conditions that can mimic rotator cuff tears clinically, including supraspinatus tendinosis, calcific tendinitis, subacromial subdeltoid bursitis, greater tuberosity fracture, and adhesive capsulitis.
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Clinical Evaluation
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Patient age is important because the prevalence of tears increases with age. Approximately 40% of asymptomatic patients over 50 years old have full-thickness rotator cuff tears (10), and the prevalence of partial- and full-thickness tears in symptomatic patients over 60 years old is greater than 60% (9). Chronic causes such as repetitive micro-trauma, subacromial impingement, tendon degeneration, and hypovascularity are thought to be responsible for most tears and account for this age-dependent prevalence. Acute macrotrauma is less frequently responsible for tears (11,12).
Dinnes et al (8) recently reviewed 10 cohort studies on the clinical evaluation of the shoulder. Pooled data from four of these studies suggested that clinical examination as a whole has a sensitivity of 90% and a specificity of 54% in the detection of full-thickness rotator cuff tears. Although 23 different signs, symptoms, and tests were assessed in the 10 studies, no definite conclusion about individual tests could be reached, since too few studies evaluated any one test. In addition, there is some variability in how individual tests are performed (8). Nevertheless, a few studies have identified the most useful clinical tests for rotator cuff tears. Murrell and Walton (9) reviewed 23 clinical examinations for rotator cuff tears and found that supraspinatus weakness, weakness of external rotation, and impingement were the most useful indicators. If all three signs are positive, or if two signs are positive and the patient is at least 60 years old, the chance of partial- or full-thickness rotator cuff tear is 98%. Similarly, Litaker et al (7) showed that weakness of external rotation, patient age of at least 65 years, and night pain best helped predict the presence of partial- or full-thickness rotator cuff tear. Other clinical findings that these authors found most useful included weakness of abduction, impingement, and the "arc of pain" sign (pain during descent of the abducted arm). Weakness of external rotation, night pain, weakness of abduction, impingement, and the arc of pain sign had a sensitivity and a positive predictive value of 76% and 79%, 88% and 70%, 64% and 78%, 97% and 67%, and 98% and 67%, respectively (7). Weakness of abduction, impingement, and the arc of pain sign should be expected because rotator cuff tears usually involve the supraspinatus tendon. Weakness of external rotation is a sign of infraspinatus tear.
The supraspinatus muscle aids not only in stabilization of the shoulder joint but also in abduction of the arm. To test for weakness, the patient’s arm is straightened and then abducted 20°. The patient is then asked to abduct the arm against an applied force (Fig 1). Alternatively, supraspinatus strength can be assessed with the arm in the "empty can" (Jobe test) or "full can" position, the arm being elevated 90° in the scapular plane. In the empty can position, the arm is in full internal rotation with the thumb pointed down, whereas in the full can position, the arm is in 45° external rotation with the palm facing up (13).
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Figure 1. Clinical photograph illustrates evaluation for supraspinatus muscle weakness. With the elbow straight and the arm in 20° abduction, the patient is asked to abduct the arm (arrow) against an applied resistance.
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Clinical impingement syndrome is characterized by pain during use of the shoulder that is relieved by local subacromial anesthetic injection. The pain can be due to (a) subacromial impingement from, for example, osteophytes (outlet impingement) (14) or (b) intraarticular causes such as underlying instability or labral lesions (nonoutlet impingement) (15). To test for impingement, the patient’s arm is passively elevated to at least 170°, which maximizes contact between the acromion and underlying structures. The arm is then internally and externally rotated while adducted against the ear. If there is increased pain with either internal or external rotation, the test is positive (Fig 2 ). In addition, assessment for the arc of pain sign may be performed by having the patient actively lower the arm in the abduction plane. The test is positive when the pain is minimal at full elevation and increases as the arm descends, being maximal between 70° and 120° of abduction.
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Figure 2a. Clinical photographs illustrate evaluation for impingement. (a) The examiner fully elevates the patient’s arm (to at least 170°). (b) Next, the patient’s humerus is internally rotated (arrow) and adducted against the ear. Afterward, the humerus is externally rotated and adducted against the ear (not shown). If there is increased pain with rotation in either direction, the test is positive.
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Figure 2b. Clinical photographs illustrate evaluation for impingement. (a) The examiner fully elevates the patient’s arm (to at least 170°). (b) Next, the patient’s humerus is internally rotated (arrow) and adducted against the ear. Afterward, the humerus is externally rotated and adducted against the ear (not shown). If there is increased pain with rotation in either direction, the test is positive.
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Another way to test for overhead impingement involves stabilizing the scapula and then elevating the patient’s arm in a plane midway between the coronal and sagittal planes (Neer test) (16,17). The Hawkins test can also be performed. In this test, the arm is flexed to 90° and then internally rotated with the elbow bent slightly (16,18). Both tests are positive if there is pain, and both have high sensitivity (80%–90%) but low specificity for rotator cuff tears.
In contrast to most other tests of the shoulder, the drop-arm test has high specificity (98%) but low sensitivity (10%) for rotator cuff rupture (9,19). In this test, the patient is asked to actively abduct the arm to 90° and then to slowly lower the arm. If the arm drops abruptly with accompanying pain, the test is positive, with a 98% chance of a rotator cuff tear (9,19).
To test for weakness of external rotation (ie, by evaluating the infraspinatus and teres minor muscles), the patient is positioned with the elbow flexed 90° and the shoulder internally rotated 20°. The patient is then asked to resist an inward force (Fig 3).
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Figure 3. Clinical photograph illustrates evaluation for external rotation weakness. The patient’s elbow is flexed 90°, and the shoulder is internally rotated 20°. The examiner then places his or her hand outside the patient’s wrist and asks the patient to resist (arrow) an inward force.
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Finally, the lift-off test can be performed to evaluate the subscapularis (20). This test is performed by passively positioning the patient’s arm behind the back with the palm facing outward (Fig 4). Failure to hold the forearm and hand off the back or inability to push off against the examiner’s hand constitutes a positive test. In their report on 16 patients with isolated subscapularis tendon tears, Gerber and Krushell (20) noted that 13 patients were unable to hold the forearm off the back, whereas three were unable to push off against the examiner’s hand. Weakness of internal rotation is not a reliable indicator of subscapularis tear because there are other internal rotators of the humerus, such as the pectoralis muscle.
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Figure 4. Clinical photograph illustrates evaluation for subscapularis tear. The patient’s arm is passively positioned behind the back with the palm facing outward. The patient is then asked to lift the hand away from the back or push off against resistance.
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Radiographic Evaluation
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Impingement can be suggested radiographically by abnormalities that encroach upon the supraspinatus outlet. For example, spur formation on the undersurface of the acromioclavicular joint and an acromion with an inferolateral tilt can be seen on anteroposterior radiographs of the shoulder (21,22). In addition, a type III acromion, in which the anterior aspect of the acromion is hooked inferiorly, can be seen on a supraspinatus outlet view (a modified Y view) and has been associated with a higher prevalence of rotator cuff tears (Fig 5) (23,24).
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Figure 5. Radiograph (supraspinatus outlet view) shows the normal supraspinatus muscle, which has a homogeneous appearance with a bulging superior contour (solid arrows). Note also the type III acromion (open arrow).
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Standard shoulder radiographs are usually normal in acute rotator cuff tears (25). However, an active abduction view, for which the patient abducts the shoulder to 90° or to the maximum extent possible, can be obtained to look for decreased acromiohumeral distance (
2 mm) (25). The unopposed action of the deltoid muscle actively pulling the humerus superiorly and the absence of the supraspinatus as a physical barrier due to tear and retraction of the tendon are the basis for the decreased acromiohumeral distance.
The density and contour of the supraspinatus muscle on a supraspinatus outlet view can also be used to predict the presence of a tear (26). The supraspinatus muscle should normally have homogeneous soft-tissue density and a bulging superior contour (Fig 5). A flattened or ill-defined superior contour and a heterogeneous appearance of the muscle due to low-density fatty areas are 85% and 80% accurate for tear, respectively (26).
Without the supraspinatus to stabilize the humerus and oppose the upward traction exerted on the humerus by the deltoid muscle, the humerus eventually migrates superiorly, and a high-riding humeral head (acromiohumeral distance < 7 mm) can be seen on an anteroposterior radiograph of the shoulder (27). In chronic rotator cuff tears, repetitive contact between the humeral head and the acromion can occur, resulting in remodeling and irregularity of these structures, particularly of the greater tuberosity. This condition is sometimes referred to as cuff arthropathy and can manifest as sclerosis, subchondral cysts, osteolysis, and notching or pitting of the greater tuberosity, usually with matching sclerosis and faceting or concavity in the inferolateral aspect of the acromion (28,29). With time, secondary osteophytosis in the glenohumeral joint can develop as a compensatory mechanism to maintain joint congruity (Fig 6) (28,30).
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Figure 6. Chronic rotator cuff tear. Anteroposterior radiograph demonstrates a high-riding humerus with decreased acromiohumeral distance (black arrows). Secondary cuff arthropathy is also seen, manifesting as faceting and sclerosis in the inferolateral aspect of the acromion and the superior aspect of the greater tuberosity (*). Note also the osteophytosis arising from the humerus (white arrow).
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US Evaluation
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US Technique
The technique for shoulder US and the typical US findings in rotator cuff tears have been described previously (11,12,31–33). A high-frequency (preferably 10–12-MHz) linear transducer is used. Tissue harmonic imaging can also be used because it has been shown to increase the conspicuity of tears, although not diagnostic accuracy (34). The ultrasound beam should be perpendicular to the tendon because even slight angulation can create artifactual hypoechoic to anechoic defects simulating tears (see Fig 8c). This artifact is called anisotropy, a phenomenon that is created when the interrogating ultrasound beam is not perpendicular to the highly organized parallel tendon fibers.
The US examination begins with evaluation of the biceps and subscapularis, then of the supraspinatus, and finally of the posterior structures, including the infraspinatus, teres minor muscle, and posterior glenohumeral joint. At our institution, the patient is seated on a stretcher facing the examiner, although some examiners prefer to scan from the side or from behind the patient. The clavicle, acromioclavicular joint, and spine of the scapula are useful bone landmarks.
Figure 7 demonstrates positioning for US evaluation of the biceps tendon. The forearm is supinated and placed on the thigh, bringing the bicipital groove forward. In the transverse plane, the biceps tendon is seen in the bicipital groove between the greater and lesser tuberosities (Fig 8). Turning the transducer longitudinally makes the biceps tendon appear as hyperechoic fibrillar lines interposed between the deltoid muscle and the humerus (Fig 9). The tendon can be followed from its musculotendinous junction to and then around the humeral head.
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Figure 7. Clinical photograph illustrates patient positioning for US evaluation of the long head of the biceps tendon. The forearm is supinated and placed on the thigh, bringing the bicipital groove (black line) forward.
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Figure 8a. Transverse view of the long head of the biceps tendon. (a) Clinical photograph illustrates the US transducer oriented transverse to the longitudinal course of the tendon (dashed line). Solid line indicates the clavicle. (b) US image shows the biceps tendon (arrows) in the bicipital groove between the greater (G) and lesser (L) tuberosities. (c) US image obtained with the ultrasound beam not perpendicular to the tendon (arrows) demonstrates anisotropy, in which the tendon appears artifactually hypoechoic to anechoic.
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Figure 8b. Transverse view of the long head of the biceps tendon. (a) Clinical photograph illustrates the US transducer oriented transverse to the longitudinal course of the tendon (dashed line). Solid line indicates the clavicle. (b) US image shows the biceps tendon (arrows) in the bicipital groove between the greater (G) and lesser (L) tuberosities. (c) US image obtained with the ultrasound beam not perpendicular to the tendon (arrows) demonstrates anisotropy, in which the tendon appears artifactually hypoechoic to anechoic.
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Figure 8c. Transverse view of the long head of the biceps tendon. (a) Clinical photograph illustrates the US transducer oriented transverse to the longitudinal course of the tendon (dashed line). Solid line indicates the clavicle. (b) US image shows the biceps tendon (arrows) in the bicipital groove between the greater (G) and lesser (L) tuberosities. (c) US image obtained with the ultrasound beam not perpendicular to the tendon (arrows) demonstrates anisotropy, in which the tendon appears artifactually hypoechoic to anechoic.
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Figure 9a. Longitudinal view of the long head of the biceps tendon. (a) Clinical photograph illustrates the US transducer oriented longitudinal to the tendon. Black line indicates the clavicle. (b) On a US image, the biceps tendon (arrows) manifests as echogenic fibrillar lines interposed between the deltoid muscle (D) and the humerus (H).
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Figure 9b. Longitudinal view of the long head of the biceps tendon. (a) Clinical photograph illustrates the US transducer oriented longitudinal to the tendon. Black line indicates the clavicle. (b) On a US image, the biceps tendon (arrows) manifests as echogenic fibrillar lines interposed between the deltoid muscle (D) and the humerus (H).
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To evaluate the subscapularis tendon, the patient’s arm is externally rotated, making sure to keep the elbow as close to the body as possible (Fig 10). This maneuver brings the tendon into a more anterior position. Rotating the transducer 90° so that it is oriented transverse to the arm allows the longitudinal extent of the subscapularis tendon to be seen as the tendon inserts on the lesser tuberosity (Fig 11). Some fibers extend across the bicipital groove to form the transverse humeral ligament, which anchors the extraarticular portion of the long head of the biceps tendon in place. On transverse images, the individual tendon slips of the subscapularis tendon can be seen (Fig 12).
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Figure 10. Clinical photograph illustrates patient positioning for US evaluation of the subscapularis tendon. The arm is externally rotated, bringing the tendon (black box) into a more anterior position.
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Figure 11a. Longitudinal view of the subscapularis tendon. (a) Clinical photograph illustrates the US transducer oriented transverse to the arm but longitudinal to the subscapularis tendon (shaded box). (b, c) On US images, the subscapularis tendon (small arrows in b, arrows in c) is seen at its insertion site on the lesser tuberosity (L) and extending to the bicipital groove (B). By externally rotating the humerus in the direction indicated by the large arrow in b, more of the tendon is brought into view (cf c). (d) Corresponding axial proton-density–weighted MR image also shows the subscapularis tendon (arrows). The box corresponds to the field of view in the US images.
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Figure 11b. Longitudinal view of the subscapularis tendon. (a) Clinical photograph illustrates the US transducer oriented transverse to the arm but longitudinal to the subscapularis tendon (shaded box). (b, c) On US images, the subscapularis tendon (small arrows in b, arrows in c) is seen at its insertion site on the lesser tuberosity (L) and extending to the bicipital groove (B). By externally rotating the humerus in the direction indicated by the large arrow in b, more of the tendon is brought into view (cf c). (d) Corresponding axial proton-density–weighted MR image also shows the subscapularis tendon (arrows). The box corresponds to the field of view in the US images.
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Figure 11c. Longitudinal view of the subscapularis tendon. (a) Clinical photograph illustrates the US transducer oriented transverse to the arm but longitudinal to the subscapularis tendon (shaded box). (b, c) On US images, the subscapularis tendon (small arrows in b, arrows in c) is seen at its insertion site on the lesser tuberosity (L) and extending to the bicipital groove (B). By externally rotating the humerus in the direction indicated by the large arrow in b, more of the tendon is brought into view (cf c). (d) Corresponding axial proton-density–weighted MR image also shows the subscapularis tendon (arrows). The box corresponds to the field of view in the US images.
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Figure 11d. Longitudinal view of the subscapularis tendon. (a) Clinical photograph illustrates the US transducer oriented transverse to the arm but longitudinal to the subscapularis tendon (shaded box). (b, c) On US images, the subscapularis tendon (small arrows in b, arrows in c) is seen at its insertion site on the lesser tuberosity (L) and extending to the bicipital groove (B). By externally rotating the humerus in the direction indicated by the large arrow in b, more of the tendon is brought into view (cf c). (d) Corresponding axial proton-density–weighted MR image also shows the subscapularis tendon (arrows). The box corresponds to the field of view in the US images.
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Figure 12a. Transverse view of the subscapularis tendon. US image (a) and corresponding sagittal oblique fat-suppressed T2-weighted MR image (b) show the subscapularis tendon (arrows in b). Note the echogenic tendon slips (arrows in a). The box in b corresponds to the field of view in a.
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Figure 12b. Transverse view of the subscapularis tendon. US image (a) and corresponding sagittal oblique fat-suppressed T2-weighted MR image (b) show the subscapularis tendon (arrows in b). Note the echogenic tendon slips (arrows in a). The box in b corresponds to the field of view in a.
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For visualization of the supraspinatus tendon, the patient’s hand is placed either behind the back or on the buttock with the elbow pointed posteriorly (Fig 13). This position exposes the supraspinatus tendon by bringing it out from underneath the acromioclavicular joint and brings into view the insertion of the tendon on the superior aspect of the greater tuberosity. The US transducer should be oriented 45°, or approximately midway between the coronal and sagittal planes, to demonstrate the longitudinal course of the supraspinatus tendon. The course of the spine of the scapula is a useful reference plane (Fig 14 ). The transducer is then rotated 90° to demonstrate the tendon in the transverse plane (Fig 15). In this plane, the deltoid muscle, which is hypo-echoic in hyperechoic fascial planes, is just deep to the subcutaneous fat. Underneath the deltoid muscle is the anechoic subacromial subdeltoid bursa surrounded by hyperechoic peribursal fat. The supraspinatus tendon appears hyperechoic and fibrillar and sits directly on the humerus. A thin anechoic rim of cartilage covers the hyper-echoic bone cortex.
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Figure 13. Clinical photograph illustrates patient positioning for US evaluation of the supraspinatus tendon. The hand is placed on the buttock with the elbow pointed backward, bringing the insertion site (i) of the supraspinatus tendon (shaded box) on the superior aspect of the greater tuberosity out from beneath the acromion and into view.
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Figure 14a. Longitudinal view of the supraspinatus tendon. (a) Clinical photograph illustrates the US transducer placed anterior to the acromioclavicular joint and roughly parallel to the spine of the scapula (black line on top of shoulder) for longitudinal evaluation of the supraspinatus tendon (shaded box). Black line on front of shoulder indicates the clavicle. (b, c) US image (b) and corresponding coronal oblique proton-density–weighted MR image (c) demonstrate the supraspinatus tendon (arrows). The box in c corresponds to the field of view in b.
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Figure 14b. Longitudinal view of the supraspinatus tendon. (a) Clinical photograph illustrates the US transducer placed anterior to the acromioclavicular joint and roughly parallel to the spine of the scapula (black line on top of shoulder) for longitudinal evaluation of the supraspinatus tendon (shaded box). Black line on front of shoulder indicates the clavicle. (b, c) US image (b) and corresponding coronal oblique proton-density–weighted MR image (c) demonstrate the supraspinatus tendon (arrows). The box in c corresponds to the field of view in b.
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Figure 14c. Longitudinal view of the supraspinatus tendon. (a) Clinical photograph illustrates the US transducer placed anterior to the acromioclavicular joint and roughly parallel to the spine of the scapula (black line on top of shoulder) for longitudinal evaluation of the supraspinatus tendon (shaded box). Black line on front of shoulder indicates the clavicle. (b, c) US image (b) and corresponding coronal oblique proton-density–weighted MR image (c) demonstrate the supraspinatus tendon (arrows). The box in c corresponds to the field of view in b.
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Figure 15a. Transverse view of the supraspinatus tendon. (a) Photograph shows transducer position for transverse evaluation of the supraspinatus tendon (box). The transducer is turned 90° (cf Fig 14a). Black lines indicate the spine of the scapula and the clavicle. (b) Transverse US image of the shoulder shows the deltoid muscle, peribursal fat (arrowheads) surrounding the subacromial subdeltoid bursa (small arrows), the supraspinatus tendon, and the cartilage (c) and underlying cortex of the humerus (large arrows). (c) US image shows how moving the transducer more anteriorly and inferiorly around the humeral head curvature brings the round hyperechoic biceps tendon (dashed oval) into view. About 2.0–2.5 cm of tendon posterior to the biceps tendon is the supraspinatus tendon (cursors), with the infraspinatus tendon more posterior. (d) Sagittal oblique fat-suppressed proton-density–weighted MR image shows the supraspinatus tendon in the transverse plane (arrows). Box corresponds to field of view in b.
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Figure 15b. Transverse view of the supraspinatus tendon. (a) Photograph shows transducer position for transverse evaluation of the supraspinatus tendon (box). The transducer is turned 90° (cf Fig 14a). Black lines indicate the spine of the scapula and the clavicle. (b) Transverse US image of the shoulder shows the deltoid muscle, peribursal fat (arrowheads) surrounding the subacromial subdeltoid bursa (small arrows), the supraspinatus tendon, and the cartilage (c) and underlying cortex of the humerus (large arrows). (c) US image shows how moving the transducer more anteriorly and inferiorly around the humeral head curvature brings the round hyperechoic biceps tendon (dashed oval) into view. About 2.0–2.5 cm of tendon posterior to the biceps tendon is the supraspinatus tendon (cursors), with the infraspinatus tendon more posterior. (d) Sagittal oblique fat-suppressed proton-density–weighted MR image shows the supraspinatus tendon in the transverse plane (arrows). Box corresponds to field of view in b.
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Figure 15c. Transverse view of the supraspinatus tendon. (a) Photograph shows transducer position for transverse evaluation of the supraspinatus tendon (box). The transducer is turned 90° (cf Fig 14a). Black lines indicate the spine of the scapula and the clavicle. (b) Transverse US image of the shoulder shows the deltoid muscle, peribursal fat (arrowheads) surrounding the subacromial subdeltoid bursa (small arrows), the supraspinatus tendon, and the cartilage (c) and underlying cortex of the humerus (large arrows). (c) US image shows how moving the transducer more anteriorly and inferiorly around the humeral head curvature brings the round hyperechoic biceps tendon (dashed oval) into view. About 2.0–2.5 cm of tendon posterior to the biceps tendon is the supraspinatus tendon (cursors), with the infraspinatus tendon more posterior. (d) Sagittal oblique fat-suppressed proton-density–weighted MR image shows the supraspinatus tendon in the transverse plane (arrows). Box corresponds to field of view in b.
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Figure 15d. Transverse view of the supraspinatus tendon. (a) Photograph shows transducer position for transverse evaluation of the supraspinatus tendon (box). The transducer is turned 90° (cf Fig 14a). Black lines indicate the spine of the scapula and the clavicle. (b) Transverse US image of the shoulder shows the deltoid muscle, peribursal fat (arrowheads) surrounding the subacromial subdeltoid bursa (small arrows), the supraspinatus tendon, and the cartilage (c) and underlying cortex of the humerus (large arrows). (c) US image shows how moving the transducer more anteriorly and inferiorly around the humeral head curvature brings the round hyperechoic biceps tendon (dashed oval) into view. About 2.0–2.5 cm of tendon posterior to the biceps tendon is the supraspinatus tendon (cursors), with the infraspinatus tendon more posterior. (d) Sagittal oblique fat-suppressed proton-density–weighted MR image shows the supraspinatus tendon in the transverse plane (arrows). Box corresponds to field of view in b.
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Moving the transducer anteriorly around the curvature of the humeral head in the oblique transverse plane allows visualization of the hyperechoic biceps tendon. The biceps tendon is used as a reference point for determining the location and size of tears. The supraspinatus tendon is the 2.0–2.5 cm of cuff tissue immediately posterior to the biceps tendon, with the infraspinatus tendon more than 2.5 cm posterior (Fig 15c). To evaluate the supraspinatus muscle, the transducer is positioned anterior and parallel to the spine of the scapula in the supraspinatus fossa (Fig 16).
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Figure 16a. Longitudinal view of the supraspinatus muscle. (a) Clinical photograph illustrates the transducer placed in the supraspinatus fossa, anterior and parallel to the spine of the scapula (black line). (b) US image shows the supraspinatus muscle (arrows) interposed between the trapezius muscle and the scapula.
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Figure 16b. Longitudinal view of the supraspinatus muscle. (a) Clinical photograph illustrates the transducer placed in the supraspinatus fossa, anterior and parallel to the spine of the scapula (black line). (b) US image shows the supraspinatus muscle (arrows) interposed between the trapezius muscle and the scapula.
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Finally, the infraspinatus muscle and tendon and the posterior glenohumeral joint are evaluated. The arm is placed in the same position as that used for evaluation of the biceps tendon. The transducer is positioned just inferior and parallel to the spine of the scapula, bringing the infraspinatus muscle into view. The infraspinatus muscle is then followed laterally as it crosses the posterior glenohumeral joint and becomes the tendon. The evaluation of the infraspinatus tendon can be optimized with internal rotation of the humerus by having the patient reach for the opposite arm. The posterior labrum is also demonstrated by moving the transducer medially in this orientation and appears homogeneous, hyperechoic, and triangular (Fig 17).
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Figure 17a. Evaluation of the posterior aspect of the shoulder. (a) Clinical photograph illustrates the US transducer position. (b, c) US image (b) and axial gradient-echo MR image (c) show the posterior aspect of the glenohumeral joint. The normal posterior labrum (arrows) is homogeneously hyperechoic at US and hypointense at MR imaging. The box in c corresponds to the field of view in b.
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Figure 17b. Evaluation of the posterior aspect of the shoulder. (a) Clinical photograph illustrates the US transducer position. (b, c) US image (b) and axial gradient-echo MR image (c) show the posterior aspect of the glenohumeral joint. The normal posterior labrum (arrows) is homogeneously hyperechoic at US and hypointense at MR imaging. The box in c corresponds to the field of view in b.
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Figure 17c. Evaluation of the posterior aspect of the shoulder. (a) Clinical photograph illustrates the US transducer position. (b, c) US image (b) and axial gradient-echo MR image (c) show the posterior aspect of the glenohumeral joint. The normal posterior labrum (arrows) is homogeneously hyperechoic at US and hypointense at MR imaging. The box in c corresponds to the field of view in b.
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On these posterior images, fluid in the axillary pouch and posterior recess of the glenohumeral joint can also be detected. The posterior recess is deep to the infraspinatus tendon, whereas the axillary pouch lies along the inferior edge of the teres minor muscle. The appearance of fluid in the posterior recess can be accentuated by having the patient rotate the arm externally. The glenohumeral joint also communicates with the sheath of the long head of the biceps tendon, and fluid in the tendon sheath may indicate a joint effusion.
US Appearances of Disease
Tears of the rotator cuff tendons are classified as either full thickness or partial thickness. Full-thickness tears extend from the bursal surface to the articular surface. Partial-thickness tears are focal defects in the tendon that involve only the bursal or articular surface.
Full-thickness rotator cuff tears usually appear as hypoechoic or anechoic defects in which fluid has replaced the area of the torn tendon (Fig 18). Fluid in the region of the torn tendon can also allow increased through-transmission of the ultrasound beam, accentuating the appearance of the underlying cartilage. Thus, two hyperechoic lines representing the cartilage and the cortex are seen, producing the "double cortex" or "cartilage interface" sign (Fig 18b). Furthermore, compression over the focal hypoechoic defect will displace the fluid and produce loss of the normal convex contour of the peribursal fat. Loss of normal contour may be seen even without compression if there is no fluid present in the area of the torn and retracted tendon. In this situation, depression of the overlying hyperechoic peribursal fat into the tendon gap occurs, creating the "sagging peribursal fat" sign (Fig 19). Atrophy of the muscle, which manifests at US as increased echogenicity and decreased bulk of the muscle, has also been associated with tears of the tendon, with tears noted in 77% of examinations that demonstrate muscle atrophy (35). Finally, in massive tears of the supraspinatus tendon, the tendon may be retracted under the acromioclavicular joint and not visualized at US. Thus, direct signs of tear include non-visualization of the supraspinatus tendon and hypoechoic discontinuity of the tendon, whereas indirect signs include the double cortex sign, the sagging peribursal fat sign, compressibility, and muscle atrophy.
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Figure 18a. Full-thickness tear of the supraspinatus tendon. (a) Longitudinal US image demonstrates a full-thickness hypoechoic defect in the normal location of the supraspinatus tendon (arrows). This defect represents fluid and extends from the bursal surface to the articular surface. Note the torn edge of the retracted supraspinatus tendon (S). (b) Transverse US image shows an intact infraspinatus tendon (i) posterior to the tear. The double cortex sign can also be seen; the overlying fluid accentuates the appearance of the cartilage (arrows), which is almost as hyperechoic as the underlying cortex. (c) Corresponding coronal oblique fat-suppressed T2-weighted MR image shows the full-thickness defect (arrows) and the torn retracted edge of the supraspinatus tendon (S). The box corresponds to the field of view in a.
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Figure 18b. Full-thickness tear of the supraspinatus tendon. (a) Longitudinal US image demonstrates a full-thickness hypoechoic defect in the normal location of the supraspinatus tendon (arrows). This defect represents fluid and extends from the bursal surface to the articular surface. Note the torn edge of the retracted supraspinatus tendon (S). (b) Transverse US image shows an intact infraspinatus tendon (i) posterior to the tear. The double cortex sign can also be seen; the overlying fluid accentuates the appearance of the cartilage (arrows), which is almost as hyperechoic as the underlying cortex. (c) Corresponding coronal oblique fat-suppressed T2-weighted MR image shows the full-thickness defect (arrows) and the torn retracted edge of the supraspinatus tendon (S). The box corresponds to the field of view in a.
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Figure 18c. Full-thickness tear of the supraspinatus tendon. (a) Longitudinal US image demonstrates a full-thickness hypoechoic defect in the normal location of the supraspinatus tendon (arrows). This defect represents fluid and extends from the bursal surface to the articular surface. Note the torn edge of the retracted supraspinatus tendon (S). (b) Transverse US image shows an intact infraspinatus tendon (i) posterior to the tear. The double cortex sign can also be seen; the overlying fluid accentuates the appearance of the cartilage (arrows), which is almost as hyperechoic as the underlying cortex. (c) Corresponding coronal oblique fat-suppressed T2-weighted MR image shows the full-thickness defect (arrows) and the torn retracted edge of the supraspinatus tendon (S). The box corresponds to the field of view in a.
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Figure 19. Sagging peribursal fat sign. Longitudinal US image shows a mildly retracted tear of the supraspinatus tendon (S), with sagging of the overlying hyperechoic peribursal fat (arrows).
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Cortical irregularity of the greater tuberosity and shoulder joint effusion, which manifests as anechoic fluid in the axillary pouch, posterior recess, and sheath of the long head of the biceps tendon, are also considered secondary signs of rotator cuff tear (Fig 20). In fact, Jacobson et al (36) noted that the combination of these two findings at US is helpful in the diagnosis of tears, with a sensitivity of 60% and a specificity of 100%.
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Figure 20a. Shoulder joint effusion tracking into the biceps tendon sheath. Transverse US image (a) and axial gradient-echo MR image (b) demonstrate an effusion in the biceps tendon sheath (arrows). The box in b corresponds to the field of view in a.
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Figure 20b. Shoulder joint effusion tracking into the biceps tendon sheath. Transverse US image (a) and axial gradient-echo MR image (b) demonstrate an effusion in the biceps tendon sheath (arrows). The box in b corresponds to the field of view in a.
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Partial-thickness tears manifest as focal, well-defined hypoechoic or anechoic defects in the tendon but involve only the bursal or articular surface (Fig 21). The extension of the hypoechoic defect to the bursal or articular surface should be visualized in two orthogonal imaging planes to confirm the finding. Cortical pitting and irregularity can also be seen with partial-thickness tears. Van Holsbeeck et al (37) reported a sensitivity and a specificity of 93% and 94%, respectively, for detection of partial-thickness tears of the rotator cuff at US.
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Figure 21a. Partial-thickness tear of the supraspinatus tendon. Longitudinal US image (a) and coronal oblique fat-suppressed T2-weighted MR image (b) show a focal, well-defined defect in the supraspinatus tendon (arrow in a) extending to the articular surface with cortical irregularity and a small subacromial effusion. The box in b corresponds to the field of view in a.
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Figure 21b. Partial-thickness tear of the supraspinatus tendon. Longitudinal US image (a) and coronal oblique fat-suppressed T2-weighted MR image (b) show a focal, well-defined defect in the supraspinatus tendon (arrow in a) extending to the articular surface with cortical irregularity and a small subacromial effusion. The box in b corresponds to the field of view in a.
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The subscapularis tendon can also be torn, usually in combination with a supraspinatus tendon tear; isolated subscapularis tears are relatively rare (38). With rupture or articular surface tear of both the subscapularis tendon and the coracohumeral ligament, the long head of the biceps tendon can dislocate medially or become subluxated onto the lesser tuberosity (Fig 22). The biceps tendon can also become subluxated in the absence of a subscapularis tendon tear due to rupture of only the coracohumeral ligament (39,40).
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Figure 22a. Subscapularis tendon tear with subluxation of the long head of the biceps tendon. Transverse US image (a) and axial proton-density–weighted MR image (b) show a tear of the subscapularis tendon (arrow), with the biceps tendon (b) perched on the lesser tuberosity (L).
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Figure 22b. Subscapularis tendon tear with subluxation of the long head of the biceps tendon. Transverse US image (a) and axial proton-density–weighted MR image (b) show a tear of the subscapularis tendon (arrow), with the biceps tendon (b) perched on the lesser tuberosity (L).
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Differential Diagnosis
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Not all pain and weakness of the shoulder are due to rotator cuff tears, and other potential clinical mimics of rotator cuff tears, such as supraspinatus tendinosis, calcific tendinitis, subacromial sub-deltoid bursitis, greater tuberosity fracture, and adhesive capsulitis, must be distinguished (39).
Tendinosis represents mucoid degeneration of a tendon without inflammation. Tendinosis is radiographically occult but can be detected at US. The tendon is thickened and heterogeneous with-out discrete defects, and an ill-defined hypo-echoic defect with indistinct borders may be present (Fig 23).
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Figure 23. Tendinosis. On a longitudinal US image, the supraspinatus tendon (arrows) is thickened and heterogeneous with no discrete defects. Instead, an ill-defined hypoechoic defect with indistinct borders is seen (*).
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In calcific tendinitis, there is deposition of calcium hydroxyapatite within the tendon. Calcium deposition is seen in the supraspinatus tendon just superior or medial to the greater tuberosity at radiography and manifests as a discrete, linear hyperechoic focus within the tendon at US (Fig 24). Posterior acoustic shadowing may be seen at gray-scale US, and hyperemia may be seen at power Doppler US (41).
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Figure 24a. Calcific tendinitis. (a) Radiograph demonstrates deposition of calcium hydroxyapatite (arrow) just superior to the greater tuberosity at the insertion site of the supraspinatus tendon. (b) US image shows calcium deposition within the supraspinatus tendon as a lobular echogenic area without shadowing (arrows). Note also the effusion in the subdeltoid bursa (*).
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Abstract
LEARNING OBJECTIVES
