The Shoulder CLINICAL PERSPECTIVE. Colm McMahon and Corrie Yablon SUMMARY OF KEY POINTS CHAPTER OUTLINE CHAPTER

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1 CHPTER 24 The Shoulder Colm McMahon and Corrie Yablon SUMMRY OF KEY POINTS In the diagnosis of full-thickness rotator cuff tears, Understanding of optimal patient positioning, probe ultrasound is of comparable accuracy to magnetic orientation, and shoulder anatomy is critical to effective resonance imaging, although it may be less accurate in the diagnostic shoulder ultrasound. diagnosis of partial-thickness tears. Ultrasound allows dynamic assessment of subacromial and The key to scanning the shoulder is meticulous technique subcoracoid impingement, biceps subluxation, and rotator using a protocol that systematically evaluates the entirety cuff integrity. of the shoulder. CHPTER OUTLINE CLINICL PERSPECTIVE SHOULDER NTOMY SCN TECHNIQUE iceps Tendon Evaluation Subscapularis Tendon Evaluation Supraspinatus Evaluation Infraspinatus, Teres Minor, and Posterior Shoulder Evaluation Rotator Cuff Musculature Evaluation ROTTOR CUFF DEGENERTION ND TERS ackground Tendinosis Full-Thickness Rotator Cuff Tears Partial-Thickness Rotator Cuff Tears Postsurgical Rotator Cuff Muscle trophy Subacromial-Subdeltoid ursa Calcific Tendinitis LONG HED ICEPS TENDON PTHOLOGY RTHROPTHY Degenerative Inflammatory PITFLLS IN SHOULDER ULTRSOUND CONCLUSION CLINICL PERSPECTIVE The human shoulder represents an intricate balanced anatomic system capable of exerting force in multiple directions, in multiple different positions, all possible because of a number of static and dynamic structures, which when functioning well provide for the competing needs of movement and stability. Proper function of the shoulder is critical for activities ranging from the most basic of daily life to many sporting pursuits including those of the throwing athlete. The shoulder is, however, prone to injury, related to anatomic factors such as subacromial impingement. 1,2 Shoulder pain and limitation of motion are very common causes for quality-of-life impairment, medical resource use, and loss of workplace productivity. 3-7 In fact, about 50% of adults have at least one episode of shoulder pain yearly. 8 Clinical presentation varies from acute injury 9,10 to more chronic dysfunction, which is more common with advancing age. 11 lthough shoulder pain and dysfunction are common clinical complaints, the underlying etiology is variable, with causes including rotator cuff pathology (degeneration, tears, calcific tendinosis), long head biceps pathology, subacromial subdeltoid bursa pathology, arthropathy of the glenohumeral or acromioclavicular joint (which may be of inflammatory or degenerative cause), or osseous disease. Of these, subacromial subdeltoid bursitis and rotator cuff pathology are the most common causes of symptomatic shoulder disease. 12 Correct diagnosis is crucial for treatment decision making, allowing appropriate management with surgical or nonsurgical treatment, which may diminish the personal and societal effect of shoulder problems. 13,14 Of course, clinical history taking and examination are intrinsic parts of patient assessment, but the accuracy of clinical examination in diagnosis of the cause of shoulder pain is both modest and variable In this clinical and socioeconomic setting, the advantages of ultrasound as a diagnostic test are myriad, as this technique is accurate, cost-effective, and well tolerated by patients. In the diagnosis of full-thickness rotator cuff tears, ultrasound is of comparable accuracy to magnetic resonance imaging (MRI), although it may be less accurate in the diagnosis of partialthickness tears Ultrasound can also determine muscle atrophy, an important parameter in predicting successful surgical outcome of rotator cuff repair. 31 Ultrasound is a good alternative to MRI in patients who are claustrophobic, are of large size, or have 877

2 878 PRT III Small Parts, Carotid rtery, and Peripheral Vessel Sonography incompatible implanted metallic and electronic devices. Patients with shoulder pain tolerate ultrasound better than MRI owing to relatively increased patient comfort and diminished examination time. 32 Ultrasound provides several benefits that MRI cannot. Ultrasound offers the possibility of dynamic assessment of the rotator cuff, allowing the patient to be imaged while engaging in the motion that causes pain or clicking. Ultrasound can assess subacromial impingement, subcoracoid impingement, and biceps tendon subluxation dynamically, in real time, and cine clips can be obtained. If there is a question as to pathology versus a normal variant, comparison to the contralateral side can be easily made. Dynamic compression of rotator cuff tears can aid in the assessment of cuff integrity. Ultrasound is also more sensitive than MRI to the detection of calcium deposits within the tendon. Finally, patients can receive the results of their examination instantaneously, and this adds tremendously to patients satisfaction with the modality. 33 It should be noted that ultrasound is not without limitations. In the clinical setting of instability, ligamentous injury, or suspected glenoid labral injury, MRI or MRI arthrography are preferred. Ultrasound is also of limited value in the evaluation of bony disorders, and plain radiography should be considered complementary in the assessment of patients with shoulder pain to further diagnosis of fracture, bone lesions, subacromial spurs, acromioclavicular osteophytes, acromiohumeral interval narrowing, glenohumeral and acromioclavicular alignment and joint space abnormality, and soft tissue calcification. In view of these considerations, ultrasound should be considered a first-line investigation in patients with acute or chronic shoulder pain in whom rotator cuff tear is suspected. Imaging algorithms detailing the role of shoulder ultrasound in specific common scenarios have been published in a consensus statement by the Society of Radiologists in Ultrasound, a highly useful resource. 34 SHOULDER NTOMY The shoulder consists of the osseous shoulder girdle with associated muscles and ligamentous structures. 35 Central to understanding the anatomy of the shoulder and scan technique is the anatomy of the scapula (Fig. 24.1). The scapula consists of a flat triangular bone with anterior and posterior surfaces in addition to the glenoid fossa laterally. The glenoid fossa is deepened by a fibrocartilaginous labrum, and lined with hyaline cartilage for articulation with the humerus at the synovial glenohumeral joint. The glenoid neck tapers to the flatter triangular body of the scapula. t the anterior aspect of the scapular body is the subscapular fossa, a concavity with oblique ridges that gives origin to the subscapularis muscle. The posterior surface of the scapula is convex posteriorly and divided into superior and inferior portions by the scapular spine. bove the spine is the supraspinatus fossa, which provides origin to the supraspinatus muscle. elow the spine is the infraspinatus fossa, with the infraspinatus muscle originating from the medial two-thirds, and the teres minor originating along the medial border. Extending superolaterally from the scapular spine is the acromion, a flattened hooklike structure that curves from posterior to anterior where it articulates with the clavicle at the acromioclavicular joint. The acromion and scapular spine give origin to the deltoid muscle. The acromion is important functionally and for the purpose of ultrasound technique as it overlies the supraspinatus and infraspinatus in the neutral position, prohibiting accurate visualization unless specific positioning maneuvers are undertaken. lso, osseous spurs (subacromial spurs) along the undersurface of the acromion may be a cause for subacromial cromion Clavicle Humeral head Humeral head Greater tuberosity Lesser tuberosity Glenoid Glenoid Humerus Scapula nterior View Posterior View FIG Illustration of the Scapula and Osseous Landmarks.

3 CHPTER 24 The Shoulder 879 cromion Coracoid process Clavicle Subscapularis Supraspinatus Supraspinatus Capsular ligament (cut) Humerus Teres minor Scapula Infraspinatus Right Shoulder nterior View Right Shoulder Posterior View FIG Illustration of Rotator Cuff natomy. impingement. These typically form at the attachment of the coracoacromial ligament. Furthermore, osteoarthritis at the acromioclavicular joint may result in osteophyte formation, which, when present inferiorly, may cause rotator cuff tendon impingement. The coracoid process is a fingerlike curved process extending anteriorly from the scapular neck, giving attachment to the short head of biceps, coracobrachialis, and pectoralis minor muscles in addition to the coracohumeral ligament, and also the coracoclavicular ligaments, which help stabilize the acromioclavicular joint. The rotator cuff consists of four muscles: the subscapularis, supraspinatus, infraspinatus, and teres minor muscles (Fig. 24.2). These originate from the scapula and insert on the proximal humerus. Normal rotator cuff tendons are about 4 to 6 mm in thickness, 36 tapering out smoothly from medial to lateral along the insertional footprint at the greater tuberosity. The subscapularis muscle is a multipennate structure that originates from the anterior surface of the scapula, which converges to a flat tendon laterally to insert on the lesser tuberosity. Of note, the inferior one-third of the subscapularis remains muscular to the level of the lesser tuberosity. 37 The supraspinatus muscle originates from and occupies the supraspinatus fossa, with its tendon extending laterally to insert on the greater tuberosity of the humerus at its anterior aspect. The tendon has a more cordlike component anteriorly and is flatter and more quadrilateral in short axis at its mid and posterior fibers. The infraspinatus muscle originates at the infraspinatus fossa and passes laterally to insert on the posterosuperior aspect of the greater tuberosity. The fibers of the supraspinatus and infraspinatus tendons merge at their posterior and anterior borders, respectively, forming a conjoint insertion. The teres minor originates along the lateral border of the scapular body and inserts along the posterior aspect of the greater tuberosity, inferior to the infraspinatus. The long head of biceps tendon originates from a bony tubercle at the superior glenoid, the supraglenoid tubercle, and from the superior labrum. It passes inferolaterally between the subscapularis and supraspinatus tendons, which form the inferior and superior borders of the rotator interval (Fig. 24.3). Within the rotator interval, the tendon is stabilized by a ligamentous sling formed by the coracohumeral and superior glenohumeral ligaments. Passing inferolaterally out of the rotator interval, the long head of biceps tendon becomes extraarticular and extends inferiorly in the bicipital or intertubercular groove, which lies between the greater and lesser tuberosities. The biceps tendon is stabilized in the groove by the transverse ligament, formed by tendinous fibers at the subscapularis insertion. 38 The subacromial-subdeltoid bursa is a synovium-lined flat, thin structure that lies between the rotator cuff tendons and the overlying deltoid muscle and acromion. 39 It serves to reduce friction between the rotator cuff and the overlying structures, permitting smooth movement. SCN TECHNIQUE For consistent and accurate shoulder ultrasound performance, a standard protocol is suggested with comprehensive evaluation in every case, rather than targeted scanning (Table 24.1) The patient should be sitting upright if possible, either on a rotating stool or at the edge of a bed. chair with a backrest should not be used, because this would interfere with patient positioning. Likewise, the sonographer should also sit on a rotating stool, with the seat position somewhat higher than the patient s, so

4 880 PRT III Small Parts, Carotid rtery, and Peripheral Vessel Sonography cromion cromioclavicular joint Coracoid process Clavicle Subscapularis Supraspinatus Lesser tuberosity Greater tuberosity icipital tendon sheath Subscapularis tendon icipital tendon iceps muscle (long head) Glenohumeral joint Scapula FIG Illustration of the Long Head iceps Tendon in the Rotator Interval and in the icipital Groove. TLE 24.1 Routine Shoulder Ultrasound Protocol Long head of biceps tendon Subscapularis tendon Supraspinatus tendon Infraspinatus tendon Teres minor tendon Supraspinatus and infraspinatus muscles Posterior shoulder cromioclavicular joint Long and short-axis static images Long and short-axis static images Dynamic evaluation for subcoracoid impingement Long and short-axis static images Dynamic evaluation for subacromial impingement Long and short-axis static images Long and short-axis static images Sagittal images panorama if possible xial plane image Coronal plane image that the sonographer s arm can be held in a natural, ergonomic position. If a patient is wheelchair-bound, it is helpful if possible to temporarily remove the backrest. If the patient cannot sit upright, more limited scanning is possible with the patient lying supine, with the affected shoulder at the edge of the bed. high-frequency 12- to 15-MHz linear array transducer is used to permit high-resolution scanning. Occasionally, in larger patients, a lower-frequency probe (9 MHz) may be needed to achieve tissue penetration to the required depth, but this incurs a reduction in resolution. When scanning any tendon, care should be taken to maintain an angle of close to 90 degrees between the probe and the tendon of interest to avoid artifactual hypoechogenicity due to anisotropy. This is discussed in more detail later in the chapter. iceps Tendon Evaluation iceps tendon evaluation is best performed with the arm in a neutral position, resting the forearm on the patient s ipsilateral thigh, with elbow flexed and the palm up (Fig. 24.4). In this position, the biceps tendon is seen anteriorly. 45 The tendon can be imaged in its short axis within the bicipital groove by holding the probe transversely with respect to the upper arm and following the course of the tendon inferiorly where it passes deep to the pectoralis major tendon insertion on the humerus. In short axis, the tendon appears as a homogeneous, echogenic, round or ovoid structure that may be accompanied by a trace of fluid within its tendon sheath. The normal biceps tendon is 2 to 4 mm thick. 36 The tendon can be followed superiorly and medially into the rotator interval, by angling the probe more obliquely to remain orthogonal to its short axis. Finally, the probe can be rotated 90 degrees to view the tendon in its long axis where it should appear smooth and fibrillar. Subscapularis Tendon Evaluation The subscapularis is scanned with the patient s arm at the side, in external rotation with the palm facing up 44 (Fig. 24.5). The tendon should be evaluated in long axis, with the probe aligned with the subscapularis tendon, and in short axis, with the probe held perpendicular to the subscapularis tendon. The coracoid process of the scapula, medial to the subscapularis and palpable in many patients, is a useful anatomic landmark when locating the subscapularis tendon. The tendon fibers can be seen emanating from the broad multipennate muscle belly. The normal hypoechoic muscle should not be mistaken for fluid. In this position the patient s arm can be rotated from external rotation to neutral position, while observing the passage of the tendon fibers deep to the coracoid process to assess for subcoracoid impingement (Video 24.1). This dynamic maneuver is also useful to assess for long head biceps tendon subluxation from the bicipital groove.

5 CHPTER 24 The Shoulder 881 C D FIG Long Head iceps Tendon (LHT). () Photograph of the probe position for imaging the LHT in short axis. The patient s shoulder is externally rotated, with the elbow flexed and held tight to the body, with the forearm palm up, resting on the patient s lap. This position rotates the LHT anteriorly. () Short-axis image of LHT (arrow). (C) Photograph of probe position for imaging the LHT in long axis. The probe is rotated 90 degrees to the short-axis starting position. Patient position remains the same as for the short-axis image. (D) Long-axis image of LHT (arrowheads). Supraspinatus Evaluation In neutral position the supraspinatus tendon is largely obscured from view by the overlying acromion. To draw the tendon out from under the acromion, specific maneuvers are needed. The position, originally described by Crass 46 (Fig. 24.6), consists of asking the patient to place his or her hand behind the back, reaching toward the opposite back pocket with the back of the hand. This results in flexion, internal rotation, and adduction of the shoulder. In this position, the greater tuberosity is located anteriorly, so the supraspinatus tendon courses anterolaterally to its insertion and is drawn out from under the acromion, allowing visualization. Patients with shoulder pain often find this position difficult to achieve and maintain, so an alternative position is the modified Crass position (Fig. 24.7) in which the patient puts the palm of the hand on the ipsilateral hip or buttock, with elbow flexed and directed posteriorly. In this position, the greater tuberosity is similarly positioned as in the original Crass position, but the maneuver is usually well tolerated by patients. The supraspinatus tendon will again course anterolaterally to the greater tuberosity. To visualize the supraspinatus in long axis, the probe should parallel the long-axis orientation of the tendon, resulting in an oblique sagittal probe position relative to the patient, with the probe directed toward the patient s ear (see Fig. 24.7). The long head biceps tendon in long axis with the patient in the modified Crass position is a useful landmark for locating the most anterior portion of the supraspinatus tendon (Fig. 24.8). If the probe in long axis is then moved posteriorly in the same plane, the entire supraspinatus will be assessed. Correctly imaged, the normal supraspinatus should appear smooth, echogenic, and fibrillar, tapering at its insertion or footprint with a so called bird s beak appearance. Normal rotator cuff tendons possess a fibrocartilaginous interface at their bony attachment that may manifest as a thin hypoechoic band paralleling the insertional cortex, similar in echogenicity to hyaline cartilage. 37 This should not be mistaken for a tear. The probe is then rotated 90 degrees to image the tendon in short axis. In this position, the more cordlike anterior fibers of the supraspinatus tendon are seen merging with the flatter quadrilateral mid and posterior fibers. While visualizing the supraspinatus tendon in short axis, it is important to move the probe anteriorly so that the long head biceps tendon is imaged in short axis. This ensures that the entire anterior leading edge of the supraspinatus has been evaluated. In short axis, the rotator interval is well seen

6 882 PRT III Small Parts, Carotid rtery, and Peripheral Vessel Sonography C D FIG Subscapularis Tendon. () Long-axis probe position. From the long head biceps tendon (LHT) starting position, the patient now externally rotates the elbow, keeping the elbow tight to the body with the palm up. This position elongates the subscapularis tendon and rotates the tendon out from under the coracoid process, allowing visualization. The probe is placed across from the coracoid process. Note that the probe position is similar for imaging the LHT in short axis, but the patient s position is different. () Long-axis image of subscapularis tendon (arrowheads). (C) Short-axis probe position. From the long-axis starting position, the probe is simply turned 90 degrees to image the subscapularis in short axis, with the patient remaining in the same position. Note that the probe position is similar to the LHT long-axis probe position, but the patient s position is different. (D) Short-axis image of subscapularis tendon (arrowheads). See also Video anterior to the tendon, with the biceps tendon coursing through the interval, also in short axis, stabilized by the coracohumeral ligament and superior glenohumeral ligament. s with all tendons, the supraspinatus should be scanned through its entirety from anterior to posterior in long axis and medial to lateral in short axis. When the posterior fibers of the supraspinatus tendon are reached, the more posteriorly oriented fibers of the infraspinatus tendon are routinely encountered; this is a helpful landmark to ensure the entire supraspinatus tendon has been studied. It is important to note that as the transducer is moved posteriorly, the greater tuberosity changes shape, from ledgelike to flat. This area of transition is where the anterior infraspinatus fibers overlap the posterior supraspinatus fibers. discrete overlap of fibers can be visualized at this juncture (Fig. 24.9, Video 24.2). Continuing posteriorly from this overlap, the infraspinatus fibers can be evaluated in their entirety, looking for the similar normal fibrillar pattern in the long axis, and the echogenic appearance in the short axis. The rotator cable is a thin fibrous band contiguous with the coracohumeral ligament that passes along the deep surface of the supraspinatus and infraspinatus tendons. 47 This bandlike structure is oriented perpendicular to the long axis of the rotator cuff, running in an anterior to posterior direction, and is felt to have a biomechanical role in stress distribution, likened to the cable of a suspension bridge. 48 It can be visualized consistently with ultrasound, seen in its short axis where it appears elliptical, when scanning the long axis of the supraspinatus and infraspinatus (Fig ). It is located about 1 cm (average 9 mm, range 4-15 mm 47 ) medial to the rotator cuff insertion at the greater tuberosity. Dynamic assessment for subacromial impingement of the supraspinatus can now be performed. The patient s arm rests in a neutral position at his or her side, and the probe is positioned in a coronal plane, with the acromion at the medial aspect of the field of view, and the greater tuberosity laterally. The patient then abducts the arm slowly, and the motion of the supraspinatus

7 CHPTER 24 The Shoulder 883 tendon under the acromion is observed. The motion should be smooth and uninterrupted, without deformation of the tendon under the acromion, deformation of the bursa, or pooling of bursal fluid (Video 24.3). useful alternative technique to assess the supraspinatus has been described by Turrin and Cappello. 49 In this technique, the patient lies supine with the affected shoulder at the edge of the bed, but allows the arm to drop over the side of the bed, with the elbow extended and the forearm pronated. This can be particularly helpful in patients who are unable to sit for example following cerebrovascular accident with hemiplegia, when associated shoulder pain is not uncommon, though of varied etiology (related to subluxation, spasticity, adhesive capsulitis, or rotator cuff tears), and standard positioning in the seated position may be difficult. 50 FIG Crass Position. The patient places her arm behind her back with the dorsum of the hand resting on the contralateral back pocket. This position rotates the supraspinatus tendon from underneath the acromion. Infraspinatus, Teres Minor, and Posterior Shoulder Evaluation Several methods of evaluation of the infraspinatus have been described. The patient can remain in the modified Crass position, or with the arm hanging at the side, and scanning can simply C D FIG Supraspinatus Tendon and Modified Crass Position. Probe position for supraspinatus in long axis, with the patient in the modified Crass position. The patient places her arm behind her back, palm on the ipsilateral back pocket, with the elbow straight back, as tight to the body as possible. This position rotates the supraspinatus from underneath the acromion. This position is usually better tolerated by patients who have a rotator cuff tear. () The probe is placed somewhat obliquely, directed toward the patient s ear. () Long-axis image of the supraspinatus tendon (arrowheads). (C) Short-axis probe position. The patient remains in the modified Crass position and the probe is rotated 90 degrees from the long-axis starting position. (D) Short-axis image of the supraspinatus tendon (arrowheads). Note that the long head of biceps tendon is visualized anterior to the supraspinatus tendon (arrow).

8 884 PRT III Small Parts, Carotid rtery, and Peripheral Vessel Sonography be continued posteriorly from the supraspinatus both in long and short axis. n alternate position of scanning the infraspinatus has been described, in which the patient is asked to bring the arm forward across the chest, resting the hand on the contralateral shoulder. 44,51 These positions allow imaging of the infraspinatus tendon and muscle. The probe is held in an oblique transverse orientation, placed on the posterior shoulder to parallel the long axis of the infraspinatus tendon, using the inferior border of the scapular spine as a visual landmark (Fig ). In long axis the tendon appears similar to the supraspinatus in morphology, although having a more elongated tapered appearance at its insertion, lacking the bird s beak appearance seen at the supraspinatus footprint. The probe is then rotated 90 degrees, to the short axis of the infraspinatus, and the tendon and muscle are evaluated. The normal muscle is hypoechoic and positioned below the scapular spine in the infraspinatus fossa. The teres minor tendon is also evaluated in this position and is seen inserting at the posterior aspect of the greater tuberosity, inferior to the infraspinatus insertion. The teres minor muscle can be seen arising from the posterolateral scapula, inferior to the infraspinatus muscle. lso in this position, the posterior shoulder is seen, with visualization of glenohumeral joint fluid and limited views of the posterior labrum and spinoglenoid notch. Scanning the posterior shoulder with external rotation may aid visualization of a glenohumeral effusion. 52 Rotator Cuff Musculature Evaluation Using the scapular spine as a visual landmark, the supraspinatus muscle in the supraspinatus fossa can be imaged by placing the probe perpendicular to the scapular spine (Fig ). This demonstrates the muscle in its short axis. The normal muscle should be hypoechoic and convex in contour, and should fill the FIG Long-xis iceps Tendon Image, With Shoulder in the Modified Crass Position. This is a good starting point for imaging the supraspinatus tendon in long axis. Once the long head biceps tendon is seen well in long axis (arrowheads), the probe can simply be moved posteriorly to image the supraspinatus tendon. FIG Overlap of Posterior Supraspinatus (rrow) and nterior Infraspinatus Fibers (rrowheads) Seen in Long xis. S ee also Video FIG Rotator Cable. () The rotator cable (arrows) is visualized in short axis along the articular surface of the supraspinatus tendon, when this tendon is imaged in long axis. () The rotator cable (arrows) is visualized as a linear structure in its long axis (arrows) along the articular surface of the supraspinatus tendon, when this tendon is imaged in short axis. (Courtesy of Dr. Yoav Morag, nn rbor, MI.)

9 CHPTER 24 The Shoulder 885 C D FIG Infraspinatus Tendon. () Long-axis probe position. The patient can simply rest the arm at the side, with the forearm palm up in the lap. The probe is placed under the scapular spine and moved laterally to see the distal insertion on the greater tuberosity. () Long-axis image of infraspinatus tendon (arrowheads). (C) Short-axis probe position. The probe is rotated 90 degrees to the infraspinatus long-axis starting position. (D) Short-axis image of infraspinatus tendon (arrowheads). C FIG Rotator Cuff Musculature. () Probe position for supraspinatus muscle. The probe is placed at the top of the shoulder, medial to the acromioclavicular joint, and posterior to the clavicle. () Probe position for infraspinatus and teres minor muscles. The probe is placed 90 degrees to the scapular spine, just inferior to the scapular spine (arrowheads). (C) Extended field-of-view image of supraspinatus (straight arrow), infraspinatus (arrowheads), and teres minor (curved arrow). Note the spine of the scapula (*) separating the supraspinatus and infraspinatus muscles.

10 886 PRT III Small Parts, Carotid rtery, and Peripheral Vessel Sonography supraspinatus fossa. The central tendon should be visible within the muscle. To image the infraspinatus and teres minor muscles, the transducer is moved distal to the scapular spine, remaining perpendicular to the spine. relative comparison and assessment of muscle volume and echogenicity can easily be made by using an extended field-of-view scan technique. ROTTOR CUFF DEGENERTION ND TERS ackground Rotator cuff dysfunction, either due to tear or to tendon degeneration, is the most common cause of referral for evaluation of the shoulder. 53 Likewise, rotator cuff disease is the most frequent cause for referral for shoulder ultrasound. The supraspinatus tendon is the most commonly injured tendon in the rotator cuff. 54 The incidence of rotator cuff tears rises as patients age. Up to 22% of patients age 65 and older have rotator cuff tears. 55 It is interesting to note that 70% of imaged patients age 65 and older have asymptomatic rotator cuff defects. 56 Rotator cuff tears in patients younger than 40 are uncommon, but they do occur in the setting of acute trauma or sports-related injuries. Rotator cuff tears in patients older than 40 are usually secondary to tendon degeneration. Tendinosis Tendinosis of the rotator cuff is a degenerative process that may be associated with shoulder pain. Histologically, there is no inflammatory component (hence the term tendinitis is not appropriate for this condition), but rather mucoid degeneration and frequently chondroid metaplasia are present. On ultrasound, tendinosis appears heterogeneous or hypoechoic, with tendon thickening, and loss of the normal fibrillar pattern 57 (Fig ). lthough discrete defects or tears are not encompassed by this diagnosis, they may coexist. Full-Thickness Rotator Cuff Tears Ultrasound is a reliable method for diagnosis of rotator cuff tears, with sensitivity and specificity over 90% 21,26,28,29,58,59 for full-thickness tears, and low interobserver variability. 60,61 Fullthickness tears are visualized as a hypoechoic or anechoic gap within the rotator cuff (Fig ), which may also have a concave contour at its bursal border. 30,62 lternatively, a greatly retracted tear can result in nonvisualization of the rotator cuff tendon 62 (Fig ). This occurs because the tendon may retract deep to the acromion, and is likely in cases in which the degree of retraction exceeds 3 cm. 63 When a full-thickness tear is present, the gap between the retracted tendon end and the greater tuberosity or distal tendon stump may be filled with hypoechoic fluid or echogenic debris (Fig ) and granulation tissue. lternatively, the subacromial-subdeltoid bursa (frequently thickened) and the deep surface of the deltoid muscle may occupy the defect created by the tear. 29 Small foci of debris within the tear gap may give the appearance of mobile or floating bright spots. 59 Fluid within the tear gap my accentuate visualization of the underlying humeral head articular cartilage owing to enhanced through transmission of the ultrasound beam, referred to as the cartilage interface sign 64 (Fig ). Occasionally one may be uncertain as to whether abnormal echotexture in the location of the rotator cuff represents a partial tear or a full-thickness tear with intervening granulation tissue and debris. Dynamic compression of the abnormal area may clarify this confusion by causing complex fluid and debris to swirl within the rotator cuff tear. It may be helpful to ascertain if a tear is more likely to be acute or chronic because acute tears are felt to have a greater chance of successful surgical outcome. In this regard, the findings of glenohumeral and bursal effusions are more common in acute tears. In addition, midsubstance tears, medial to the bone-tendon junction, are more likely to be acute. On the other hand, severely retracted tears are more likely to be chronic. 65 In chronic full-thickness tears, the tendon gap may be filled with FIG Tendinosis of the Supraspinatus. Long-axis image of the supraspinatus tendon (arrowheads) demonstrates hypoechogenicity and diffuse loss of normal fibrillar echotexture.

11 CHPTER 24 The Shoulder 887 C FIG Focal Full-Thickness Supraspinatus Tear. () Long-axis image of the anterior supraspinatus tendon demonstrates intact fibers (arrowheads). () Long-axis image of more posterior fibers of supraspinatus show a full-thickness tear with hypoechoic fluid (arrow) within the gap between the torn tendon end (arrowheads) and the greater tuberosity (*). (C) Short-axis image of supraspinatus. Intact anterior fibers (white arrowhead) are shown, with a fluid-filled gap (straight arrow) at the posterior supraspinatus tear. Intact anterior infraspinatus fibers (curved arrow) are visible posterior to the tear. ssisting in orientation, the long head biceps tendon (black arrowhead) appears anteriorly. FIG Full-Thickness Supraspinatus Tear With Retraction of the Tendon eneath the cromion. Image in the expected location of the supraspinatus tendon in long () and short () axis demonstrates absence of the tendon above the humeral head (*) and greater tuberosity (white arrow). Fluid and debris are seen in place of the normal tendon (arrowheads). Note the intact long head biceps tendon anteriorly (black arrow). noncompressible, complex echogenic debris and granulation tissue that are contiguous with the subacromial subdeltoid bursa, and this may give the false impression of rotator cuff volume to the novice practitioner. Partial-Thickness Rotator Cuff Tears s with full-thickness rotator cuff tears, partial-thickness tears occur in both younger and older patients. Partial tears occur more commonly than full-thickness tears in younger patients, and most commonly occur in young athletes. Partial articular-sided supraspinatus tears are the most common subtype in the young athlete. 66 In the older patient population, partial-thickness tears also most commonly occur in the supraspinatus tendon, but the most common cause is tendon degeneration, with increased incidence as patients age.

12 888 PRT III Small Parts, Carotid rtery, and Peripheral Vessel Sonography FIG Focal Full-Thickness Tear of Supraspinatus Tendon. In this long-axis image of the supraspinatus tendon, there is a focal full-thickness tear, and the gap between the tendon retracted end and the greater tuberosity is filled with echogenic debris (arrow) and fluid. FIG Full-Thickness Supraspinatus Tear With ssociated Cartilage Interface Sign. hyperechoic line (arrowheads) is seen along the surface of the normal hypoechoic cartilage (arrow), along the superior aspect of the humeral head (*). Partial-thickness tears are characterized by a focal area of hypoechogenicity or mixed echogenicity involving one side of the tendon, but not extending through the entire thickness. 58 There are several subtypes of partial-thickness tears of the rotator cuff (Figs and 24.19). ursal-sided partial-thickness tears (Fig and ) occur superficially, just deep to the subacromial subdeltoid bursa. rticular-sided tears (see Fig C and D) occur at the undersurface of the tendon in contiguity with the joint space. Intrasubstance tears (Fig E) can occur either within the substance of the tendon footprint at the enthesis or longitudinally within the tendon fibers. These tendons may not be identified at arthroscopy because they do not communicate with either the bursal or the articular surfaces of the tendon. specific partial-thickness tear type is the rim-rent tear (see Fig F), occurring at the articular side of the supraspinatus tendon, extending into the tendon footprint on the greater tuberosity. 67,68 This type of tear is most commonly seen in athletes who engage in overhead-throwing activities. Partial-thickness tears vary from small, 1- to 2-mm tears to those involving more than 50% of tendon thickness. lthough tears of 50% or greater have typically been referred for repair, patients with tears involving as little as 25% of the tendon may benefit from arthroscopic debridement. 69,70 Surgical decisions, however, are made in the context of the individual patient performance status, limitation by the injury, comorbidities, and patient preference. Partial tears occur most commonly along the articular side of the tendon in younger patients. 70 Care must be taken to adequately assess the anterior leading edge fibers of the supraspinatus tendon, where these tears can often occur. 71 ursalsided partial-thickness tears may manifest as flattening of the bursal contour of the tendon of varying severity. 29 This may lead to an hourglass-like diameter shift between areas of normal and attenuated tendon. 28 n associated sign frequently observed in the setting of both partial- and full-thickness rotator cuff tears is the finding of cortical irregularity of the greater tuberosity, a finding with a 75% positive predictive value for the presence of an associated rotator cuff tear. 72 This is more severe in full-thickness tears and represents bony remodeling with irregularity, pitting, and erosion. 73 second sign that can be seen in both partial articularsided and full-thickness tears is the cartilage interface sign, mentioned earlier. In analysis of partial- and full-thickness tears, it is important to quantify the extent of the tear in both its long and short axis (tear length and width); for example, in the case of a supraspinatus tendon tear, a measurement of the medial to lateral tear length should be made in long axis, and a measurement of the anterior to posterior tear width should be made on short-axis imaging. Postsurgical Rotator Cuff fter surgical rotator cuff repair, the appearance of the rotator cuff and surrounding soft tissues is abnormal, as can be expected, with loss of normal soft tissue planes and abnormal echotexture of the rotator cuff tendon. ecause of loss of normal interface with the overlying subacromial bursa, dynamic assessment may aid in identification and visualization of the supraspinatus tendon. 74 ony irregularity at the site of anchor placement is expected, and echogenic suture material within the tendon may contribute to the heterogeneous appearance of the postoperative rotator cuff tendon (Fig , Video 24.4). gap within the tendon and nonvisualization of the tendon owing to retraction are the most reliable signs for a recurrent tear. 75,76 thinned tendon or one with subtle contour abnormality is considered intact. Muscle trophy Ultrasound may also be used to assess for rotator cuff muscle atrophy, which may occur in the setting of a subacute or chronic rotator cuff tear. This is characterized by decreased muscle bulk and increased muscle echogenicity (related to increased fat interposed among muscle fibers 77 (Fig ). Ultrasound appearances also include lack of clarity of the muscle contour, and loss of visibility of the central tendon within the myotendinous

13 CHPTER 24 The Shoulder 889 Classification of Partial Tears based on depth of defect rticular surface ursal surface Grade 1 <25% thickness ( 3 mm) Grade 2 <25% 50% thickness (3-6 mm) Grade 3 >50% thickness (+6 mm) FIG Illustration of Partial Tear Subtypes. junction. 78 Extended field-of-view imaging, whereby the rotator cuff muscles are imaged in short axis side by side, may assist in reducing interobserver variability in the ultrasound diagnosis of muscle atrophy, presumably by providing an internal control between muscles. Diagnosis of muscle atrophy is of importance in clinical management because the presence of muscle atrophy is considered a negative prognostic indicator with regard to the likelihood of successful surgical repair. It is worth remembering that atrophy may also occur because of denervation. Muscle atrophy can be qualitatively graded from 0 to 4 as described by Goutallier and colleagues 79 : 0 = normal muscle, 1 = minimal fatty streaks, 2 = more muscle than fat, 3 = equal amounts of muscle and fat, 4 = more fat is present than muscle. This grading system was designed for MRI interpretation; therefore Strobel and colleagues described a modified grading system for ultrasound assessment of muscle atrophy whereby morphology and echogenicity are evaluated. 78 In this system, morphologic changes of atrophy are graded 0 to 2: grade 0 = normal, with clearly visible muscle contours, muscle fibers, and central tendon; grade 1 = only partially visible normal muscle features; grade 2 = normal structures no longer visible. Meanwhile, the echogenicity of muscle is graded in comparison with the deltoid from 0 to 2: grade 0 = isoechoic to deltoid; grade 1 = slightly hyperechoic to the deltoid muscle; grade 2 = markedly hyperechoic to deltoid muscle. Ultrasound grading of fatty atrophy has been shown to correlate well with MRI assessment. 31,80 Subacromial-Subdeltoid ursa The subacromial-subdeltoid bursa is visualized superficial to the rotator cuff tendons, deep to the deltoid muscle and acromion. 39 t its inferolateral aspect, it extends beyond the lateral margin of the rotator cuff, lying superficial to the humeral shaft. This can be a helpful observation in distinguishing this structure from the superficial fibers of the rotator cuff. On ultrasound, the subacromial-subdeltoid bursa normally consists of a thin hypoechoic band measuring less than 2 mm where synovial fluid resides within the bursa, and a thin hyperechoic line superficial and deep to this, representing the wall of the bursa and peribursal fat (Fig ). bnormalities of the subacromial-subdeltoid bursa manifest with increased fluid within and distention of the bursa, and/or by bursal wall thickening (Fig ). ursal abnormality detected

14 890 PRT III Small Parts, Carotid rtery, and Peripheral Vessel Sonography C D E F FIG Partial-Thickness Tears of the Rotator Cuff. () ursal-sided tear long-axis image. focal hypoechoic area (arrow) is shown extending from the bursal surface of the supraspinatus tendon. () ursal-sided tear short-axis image. focal hypoechoic area (arrow) is shown extending from the bursal surface of the supraspinatus tendon. (C) rticular-sided tear a focal hypoechoic tear (arrow) is present along the articular side of the supraspinatus, shown here in long axis. (D) rticular-sided tear a focal hypoechoic tear (arrow) is present along the articular side of the supraspinatus, seen here in short axis. Note the long head biceps tendon (LHT) (arrowhead) anteriorly. (E) Intrasubstance tear long-axis image of supraspinatus tendon demonstrates linear hypoechoic cleft (arrowhead) within the tendon, extending to the greater tuberosity (*) but not extending to either the bursal or articular surface of the tendon. (F) Rim-rent tear long-axis image of the supraspinatus tendon demonstrates a hypoechoic tear (arrowhead) along the articular side of the tendon, at the insertional footplate on the greater tuberosity (*). on ultrasound is highly associated with shoulder pain. 81 The most common cause for fluid distention of the bursa is an underlying rotator cuff tear, which may cause communication with the normally separate glenohumeral joint space. Uncommonly, fluid can also track through the adjacent acromioclavicular joint in this setting and into the soft tissues superficial to the acromioclavicular joint to form a ganglion ( geyser sign ) (Fig ). In this case, patients will have a lump over the acromioclavicular joint, and they often do not relate it to background shoulder pain or immobility. Complete examination of the shoulder is indicated in such cases to evaluate for underlying communicating full-thickness rotator cuff tear. This is important

15 CHPTER 24 The Shoulder 891 because the natural history of untreated asymptomatic rotator cuff tears is frequently the development of symptoms in addition to tear progression. 82 Direct trauma to the shoulder can also cause thickening and distention of the subacromial-subdeltoid bursa, sometimes with more echogenic fluid representing blood. The bursa may be chronically irritated by friction related to subacromial impingement, and may worsen this clinical syndrome. dditional inflammatory causes of subacromial subdeltoid bursa thickening and distention include rheumatoid arthritis, polymyalgia rheumatica, and hydroxyapatite deposition (calcific bursitis). Infection of the bursa can also occur either through direct inoculation or via communication with underlying septic arthritis in the setting of concomitant full-thickness rotator cuff tear. FIG Postoperative Supraspinatus Tendon. L ong-axis image of supraspinatus shows a heterogeneous (arrows) but intact supraspinatus tendon, and irregularity of the greater tuberosity (arrowheads). See also Video Calcific Tendinitis Hydroxyapatite crystal deposition within rotator cuff tendons can be a cause of severe atraumatic pain. These deposits occur most frequently in the supraspinatus tendon, slightly more FIG Fatty trophy of the Infraspinatus Muscle. Image obtained of the short axis of the infraspinatus tendon shows low-volume, hyperechoic infraspinatus muscle (arrowheads), compared with the normal echogenicity of the teres minor (*). FIG Normal Subacromial-Subdeltoid ursa. Overlying the infraspinatus tendon, in long axis, the subacromial subdeltoid bursa is visualized as a thin hypoechoic line (arrow), with thin hyperechoic borders superficial and deep to the bursa (arrowheads).

16 892 PRT III Small Parts, Carotid rtery, and Peripheral Vessel Sonography commonly than the infraspinatus tendon, and more uncommonly in the teres minor and subscapularis tendons. 83 Calcium deposits may undergo resorption, and it is during this resorptive phase that patients are most likely to be symptomatic. The hallmarks of this phase on ultrasound evaluation are fragmented, nodular or cystic echogenic deposits (Fig ), usually without shadowing, and there may be associated neovascularity on color Doppler assessment. 84 ssociated bony osteolysis at the greater tuberosity may be present and denotes a more clinically severe syndrome, with more protracted pain and functional limitation. 85 More dense arclike echogenic calcific deposits with clear posterior acoustic shadowing are more likely to be asymptomatic or less symptomatic. Ultrasound-guided treatment with direct needling and barbotage leads to short- and long-term clinical improvement in this condition. 86,87 LONG HED ICEPS TENDON PTHOLOGY The long head biceps tendon can be injured in the setting of concomitant rotator cuff tear, shoulder dislocation, or overhead sports. It has been noted by several authors that there is an association between pathologies of the long head biceps tendon and supraspinatus tendon, with coexistent injuries of these structures in 22% to 79% of cases of injury to either structure. 88 The long head biceps tendon is partly intraarticular and is extrasynovial, with a tendon sheath at the intertubercular groove that communicates with the glenohumeral joint. ecause of this, fluid in the tendon sheath may relate to intraarticular processes, particularly if associated with glenohumeral effusion. Inflammation of the tendon sheath (tenosynovitis) should be considered, however, if the tendon appears abnormal, if there is hyperemia on color Doppler imaging, if there is no sign of alternative FIG Subacromial-Subdeltoid ursal Thickening. Image shows increased fluid in the subacromial bursa (straight arrow), and thickening of the wall of the subacromial bursa (arrowheads). Note also a small bursal-sided tear of the supraspinatus at its insertion (curved arrow). FIG Calcific Tendinitis of the Supraspinatus Tendon. L ongaxis image of the supraspinatus image demonstrates a hyperechoic focus of calcification (arrowheads) within the supraspinatus tendon. FIG Full-Thickness Supraspinatus Tendon Tear With Geyser Sign. () Image obtained at the acromioclavicular joint where the patient felt a mass. The mass corresponds with a heterogeneous hypoechoic lesion (arrowheads) with internal debris and septation compatible with a complex ganglion. () Long-axis image of the supraspinatus tendon in the same patient shows a full-thickness supraspinatus tendon tear (arrow) in addition to thickening of the subacromial bursa.

17 CHPTER 24 The Shoulder 893 C FIG Long Head of iceps Tenosynovitis. () Short-axis image shows increased fluid within the long head biceps tendon sheath (arrowhead), surrounding the tendon (arrow). () Short-axis image shows hyperemia (arrowheads) in the long head of biceps tendon sheath. (C) In a different patient, long-axis image of the long head of biceps tendon shows thickening of the wall (arrowhead) of the tendon sheath and increased fluid (arrow) within the sheath. glenohumeral pathology or effusion, or if there is localizing tenderness 89 (Fig ). Long head biceps tendinosis is characterized by loss of normal tendon fibrillar pattern, abnormal hypoechogenicity, and often thickening. 90 Ultrasound is an accurate means for diagnosis of full-thickness biceps tendon tears, with more modest accuracy in the diagnosis of partial tears. 90,91 Partial-thickness tears are characterized by anechoic clefts within the tendon, without complete discontinuity. These tears are often longitudinally orientated, paralleling the tendon long axis, and may result in splitting the tendon into two distinct parallel components, termed a longitudinal split tear (Fig ). Long head biceps complete tears typically occur close to the tendon origin and may manifest with acute onset of contour deformity of the biceps muscle. The tendon will usually retract distally, often distal to the insertion of the pectoralis major, which usually inserts on the humerus just anterior to the long head biceps tendon course in the upper arm. complete tear with retraction is typically diagnosed by nonvisualization of the tendon within the intertubercular groove, 45 but care should be taken to assess for medial dislocation of the tendon as an alternative cause if the tendon is not seen within the bicipital groove. The biceps tendon is normally stabilized within the tendon groove by the thin transverse ligament. Medially, displacement is resisted by the subscapularis tendon. If the subscapularis tendon is torn at its insertion, this may allow medial displacement of the biceps tendon, deep to the subscapularis tendon. 92 lternatively, if the transverse ligament is torn, this may permit medial dislocation of the biceps tendon, which then lies superficial to the otherwise intact subscapularis tendon. RTHROPTHY Degenerative Osteoarthritis is common and characterized by the formation of marginal bone spurs osteophytes at the margin of articular surface. This is particularly common at the acromioclavicular joint (Fig ). There may be small associated joint effusions, and echogenic intraarticular bodies, which may be calcified, can be observed. Inflammatory The shoulder can be involved in inflammatory arthropathies, including rheumatoid arthritis and ankylosing spondylitis. 93,94 The shoulder involvement in rheumatoid arthritis occurs later than peripheral arthritis. Patients with inflammatory arthropathy

18 894 PRT III Small Parts, Carotid rtery, and Peripheral Vessel Sonography FIG Longitudinal Split Tear of the Long Head of iceps Tendon. Short-axis image demonstrates a hypoechoic cleft (arrow) through the long head of biceps tendon, dividing it into two components. FIG cromioclavicular Joint Osteoarthritis. Image clavicle (arrow) and capsular thickening and hypertrophy (arrowhead). of the acromioclavicular joint demonstrates osteophyte formation at the distal may have glenohumeral effusion. This is best assessed posteriorly, and a thickness of 3 mm or more from the humeral head to the capsule may represent effusion and/or synovial thickening 95 (Fig ). Ultrasound is particularly sensitive to detection of fluid in the posterior glenohumeral recess when patients are scanned with the arm in external rotation 52 (see Video 24.4). Use of color Doppler, particularly power Doppler, 96 is helpful to elucidate synovial hyperemia and can help separate thickened synovium from complex intraarticular fluid. one erosions may also be present, characterized by bony cortical surface rounded or steplike deformations, often at the humeral head margins. 97,98 Ultrasound may be used as a complementary technique to radiographs in assessment for erosions, because it may detect radiographically occult erosions, 94 although overall, MRI has greater sensitivity and can be used for problem solving. 99 In ankylosing spondylitis, acromioclavicular synovitis is common. Patients with inflammatory arthritis may also be affected by subacromial-subdeltoid bursitis, in addition to rotator cuff and biceps tendon tears. FIG Glenohumeral Joint Effusion. Image of the posterior shoulder shows increased fluid within the joint (arrow) in this patient with osteoarthritis.

19 CHPTER 24 The Shoulder 895 FIG Short-xis Images of the Supraspinatus Tendon. () rtifactual hypoechogenicity of the supraspinatus tendon (arrows) may simulate tendinosis or tear. () Correction of angle of insonation to be perpendicular to the tendon permits visualization of the normal intact supraspinatus tendon (arrows). PITFLLS IN SHOULDER ULTRSOUND nisotropy is a common problem in diagnostic shoulder ultrasound, but thankfully one that can be easily rectified. It consists of artifactual hypoechogenicity within a tendon caused by scanning with the probe in a suboptimal angle with respect to the tendon. s a highly organized linear structure, a tendon reflects ultrasound waves, effectively giving a normal echogenic appearance when the angle of insonation is close to 90 degrees. However, deviation from this angle can result in reflection of sound waves away from the transducer, leading to apparent hypoechogenicity, which can be erroneously interpreted as tendinosis or tearing. 37 This can be corrected by attention to the angle of insonation of the tendon in question and by attempting to visualize any pathologic finding in more than one plane (Fig , Video 24.5). There are several additional scanning pitfalls frequently encountered by the inexperienced sonographer. Tears of the anterior-most fibers of the supraspinatus are easily missed if scanning does not extend anteriorly enough. One way to solve this problem is to use the anatomic landmark of the long head bicipital tendon as the starting point for scanning the supraspinatus tendon, both in short and long axis. In the hands of novice operators, chronic full-thickness rotator cuff tears with echogenic granulation tissue may be confused for intact, abnormal tendon. Careful evaluation with dynamic compression, and differentiation of bursal tissue from rotator cuff tissue should be performed. In addition, inexperienced operators may mistake the junction of the posterior supraspinatus and anterior infraspinatus, where the tendon fibers overlap, as pathology. Careful angling of the probe with respect to the long axis of the fibers, and direct correlation to short-axis images should ameliorate this misperception. If the long head biceps tendon is not seen in the bicipital groove, one should not automatically assume that the tendon is torn. It is important to ensure that the transducer is perpendicular to the tendon, as otherwise the tendon may appear artifactually hypoechoic owing to anisotropy. The transducer should then be moved medially to visualize the coracoid process, to look for a medially dislocated tendon. Lastly, one should scan distally to the pectoralis junction to see if the tendon has torn and retracted distally. Soft tissue distortion by bony abnormality can cause confusion during imaging and can be rectified by referring to a concurrent radiograph. 100 This is particularly the case in the setting of recent trauma wherein an underlying fracture can cause considerable distortion, especially if the greater tuberosity is involved. s is the case for learning any skill, there is a learning curve involved when performing diagnostic shoulder ultrasound. ccuracy is lower when operators are unfamiliar with the technique, but the learning curve plateaus between 50 and 100 cases, 101 which should be considered when undertaking this examination for the first time and when training and mentoring other sonographers. CONCLUSION In conclusion, ultrasound is an accurate and cost-effective technique for diagnosing soft tissue pathology at the shoulder and is well tolerated by patients. Ultrasound confers many advantages over MRI in the evaluation of the rotator cuff. dequate experience in this technique is important, in addition to correlation with other imaging modalities when available. REFERENCES 1. C hopp-hurley JN, O Neill JM, Dickerson CR. Distribution of bone and tissue morphological properties related to subacromial space geometry in a young, healthy male population. Surg Radiol nat. 2016;38(1): Cra ik JD, Mallina R, Ramasamy V, Little NJ. Human evolution and tears of the rotator cuff. Int Orthop. 2014;38(3): T akura T, Ushida T, Kanchiku T, al. etthe societal burden of chronic pain in japan: an Internet survey. J Orthop Sci. 2015;20(4): W hite JJ, Titchener G, Fakis, al. et n epidemiological study of rotator cuff pathology using the health improvement network database. one Joint J. 2014;96-(3): V irta L, Joranger P, rox JI, Eriksson R. Costs of shoulder pain and resource use in primary health care: a cost-of-illness study in Sweden. MC Musculoskelet Disord. 2012;13:17.