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 Table of Contents  
REVIEW ARTICLE
Year : 2018  |  Volume : 13  |  Issue : 5  |  Page : 17-21

Regional sonology of the upper limb - I: Shoulder


1 Department of Radiology, Eclat Polyclinic, Mumbai, Maharashtra, India
2 Department of Imaging, Gray Scale Imaging, Vile Parle (West), Mumbai, Maharashtra, India

Date of Web Publication1-Aug-2018

Correspondence Address:
Dr. Ankit B Shah
102, Kusumkunj, 10th Road, Khar (West), Mumbai - 400 052, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0973-3698.238197

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  Abstract 


Knowledge of the anatomy of the shoulder and its periarticular soft tissues and scanning techniques are essential for successful ultrasound (US) examination of the shoulder. Inflammatory conditions or overuse injuries affecting the periarticular structures are the most common causes of nontraumatic shoulder pain. Dynamic imaging with US is an added advantage and scores over similar cross-sectional imaging modalities. In a routine US examination of the shoulder joint, the extraarticular segment of the long head of biceps, rotator-cuff tendons and their muscle bellies, rotator interval, subacromial-subdeltoid bursa, posterior joint recess, and the acromioclavicular joint are assessed systematically.

Keywords: Infraspinatus, long head biceps, musculoskeletal, rotator-cuff, shoulder, subscapularis, supraspinatus, ultrasound


How to cite this article:
Shah AB, Shah BR. Regional sonology of the upper limb - I: Shoulder. Indian J Rheumatol 2018;13, Suppl S1:17-21

How to cite this URL:
Shah AB, Shah BR. Regional sonology of the upper limb - I: Shoulder. Indian J Rheumatol [serial online] 2018 [cited 2021 Jan 23];13, Suppl S1:17-21. Available from: https://www.indianjrheumatol.com/text.asp?2018/13/5/17/238197




  Introduction Top


The relatively superficial location of the periarticular structures around the shoulder joint allows their evaluation with ultrasonography. Inflammatory conditions or overuse injuries affecting the periarticular structures are the most common causes of nontraumatic shoulder pain. Ultrasound (US) has a high spatial resolution of the periarticular soft tissues. Dynamic imaging with the US is an added advantage and scores over similar cross-sectional imaging modalities.

Knowledge and concepts of the anatomy of the shoulder and its periarticular soft-tissues aids in successful US examination of the shoulder. Discussion of the US anatomy of the shoulder would include (1) long head of biceps (LHBT), (2) Rotator-cuff, (3) rotator interval (RI), (4) subacromial-subdeltoid (SASD) bursa, (5) posterior joint recess, and (6) acromioclavicular (AC) joint.


  Long Head of Biceps Tendon Top


The LHBT tendon has intraarticular and extraarticular segments. It takes its origin from the supraglenoid tubercle and traverses horizontally in the glenohumeral joint space [Figure 1]. It exits the glenohumeral joint at the rotator-cuff interval (focal space between the subscapularis and the supraspinatus [SS] tendons). The extraarticular LHBT angulates inferiorly as it exits the RI. The extraarticular LHBT is located within the bicipital groove of the humerus which is formed by the lesser tuberosity (LT) medially and the greater tuberosity (GT) laterally. The extraarticular LHBT is surrounded by a synovial sheath known as the biceps tendon sheath (BTS). The BTS communicates with the joint cavity. The LHBT is held firmly in the bicipital groove by the coracohumeral and the transverse humeral ligaments (HLs). The transverse HL covers the proximal bicipital groove.
Figure 1: The long head of the biceps (blue) originates from the supraglenoid tubercle and travels laterally as it exits the joint. The extraarticular long head of biceps traverses the bicipital groove formed by the greater tuberosity and the lesser tuberosity 2

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US of the shoulder begins by identifying the extraarticular LHBT from the anterior aspect. The LT and GT are the osseous landmarks used to identify the location of the LHBT by placing the probe transversely on the humerus. The LHBT is seen in the short axis as an oval hyperechoic structure within the bicipital groove [Figure 2]. The presence of a small amount of fluid within the BTS is seen as a hypoechoic halo around the hyperechoic tendon. The transverse HL is seen as a hyperechoic band covering the LHBT in the proximal bicipital grove. Inferiorly, the LHBT is scanned until the attachment of the pectoralis major tendon.
Figure 2: On the short axis, the long head of the biceps is seen as a well-defined echogenic ovoid structure (*) cradled between the greater tuberosity laterally and the lesser tuberosity medially. The echogenic transverse band-like structure (arrows) is the transverse humeral ligament. The transverse humeral ligament along with the coracohumeral ligament is responsible for stabilizing the long head of biceps within the bicipital groove. The biceps tendon sheath surrounding the long head of biceps is visualized only in the presence of effusion

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Turning the probe by 90 degrees, the LHBT is seen as a fibrillary hyperechoic cord-like structure situated between echogenic humeral cortex and the deltoid muscle belly [Figure 3].
Figure 3: On the long axis, the long head of biceps is seen as an echogenic cord-like structure (markers) situated between the deltoid muscle belly and the smooth echogenic humeral cortex

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  Rotator-Cuff Top


The rotator-cuff is a short, flat, and broad musculotendinous structure formed by close interdigitation of the fibers of four tendons.[1] From anterior to posterior direction, the tendons forming the rotator-cuff include subscapularis, SS, infraspinatus, (IS), and the teres minor tendons.

Subscapularis

The subscapularis is a multipennate muscle taking its origin from the anterior surface of the scapula. It attaches to the LT [Figure 4]. The subscapularis tendon has a broad footprint measuring approximately 39.5 mm in the craniocaudal direction.[2]
Figure 4: The rotator-cuff is formed by four tendons, that is, the subscapularis, supraspinatus, infraspinatus, and teres minor. The subscpaularis attaches to the lesser tuberosity. Rest of the tendons attach to the greater tuberosity. The supraspinatus tendon passes below the coracoacromial arch formed by the Acromion and the coracoid process and attaches along the anterior aspect of greater tuberosity

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The subscapularis tendon is evaluated from the anterior aspect in the short and long axis after asking the patient to externally rotate the shoulder so that the maximum extent of the tendon is visualized after it slides outward below the coracoid process.

The tendon is seen as an echogenic fibrillar structure in the long axis as it attaches to the LT [Figure 5]. In the short axis, the subscapularis tendon is seen to have intermittent hypoechoic linear echoes [Figure 6] due to the multipennate nature of the tendon where the muscle tissue is interposed between the tendon fascicles.[3]
Figure 5: On the long axis, the subscapularis tendon (*) is seen as a broad echogenic structure attaching to the lesser tuberosity. The coracoid process is used as an osseous landmark to identify the subscapularis tendon, as the tendon emerges from its undersurface to extend laterally

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Figure 6: Multipennate subscapularis tendon on the short-axis visualized as echogenic areas interspersed with hypoechoic muscle fibers

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Supraspinatus

The SS muscle takes its origin from the supraspinous fossa along the posterior surface of the scapula. The tendon passes through a tunnel-like area formed by the coracoacromial arch (acromion, the AC joint, and the coracoid process) above and the glenohumeral joint below [Figure 4]. The tendon inserts into the upper facet of the GT with a relatively broad footprint.

The tendon is examined in the long and short axis using various maneuvers. The more commonly used position is known as the modified crass position, where the tendon is examined from the anterior aspect by asking the patient to extend the shoulder with the elbow flexed at 90° and the palm facing anteriorly. The palm is made to touch the ipsilateral hip.[4]

The SS tendon is seen as a thick, echogenic “beak-shaped” structure with fibrillar echoes and having a convex superficial margin [Figure 7]. The tendon is visualized just below the lateral margin of the acromion as it inserts over the GT. The SS tendon has a relatively broad footprint on the GT. The tendon measures 6.4 mm (±1.4 mm) in medial to the lateral direction at the site of insertion.[3] On the short axis, measuring from the anterior margin of the rotator-cuff interval, the SS tendon measures 1.8 cm–2 cm in the anteroposterior direction [Figure 8]. The posterior fibers of the SS tendon closely interdigitate with the anterior fibers of the IS tendon; hence, the posterior limit is not well delineated on imaging – this region is referred to as the conjoint tendon.
Figure 7: Long-axis view of the supraspinatus tendon (*) shows a well-defined echogenic strap-like structure arising from the undersurface of the acromion and laterally attaching over the greater tuberosity. The thin echogenic layer visualized just above the supraspinatus tendon is the peribursal fat around the subacromial- subdeltoid bursa

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Figure 8: Short-axis image of the supraspinatus tendon (*) and the rotator-cuff interval containing the long head of biceps tendon (broad arrow). The peribursal fat is visualized as a thin echogenic line (long arrows)

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Infraspinatus and teres minor

The IS arises from the infraspinous fossa of the scapula and attaches on the GT, just posterior to the attachment of the SS tendon. The teres minor muscle originates from the lateral margin of the scapula and attaches to the inferior facet of the GT.

The IS and the teres minor tendons are evaluated from the posterior aspect. The tendons are evaluated in the long and short axis after asking the patient to touch his finger to the opposite shoulder across the chest. This maneuver allows the maximum length of the tendons to be visualized. Identification of the scapular spine in the short axis (sagittal section) allows identification of the infraspinous fossa, which lies inferior to the spine.[5] Scanning the area from lateral to medial aspect shows the two echogenic tendons as separate tendons arising from the muscle bellies. The tendons are seen as well-defined echogenic structures with fibrillary pattern [Figure 9].
Figure 9: Appearance of the infraspinatus tendon (arrows) on the long axis. The scapular spine can be used as an osseous landmark to identify the infraspinatus muscle belly

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  Rotator Interval Top


The RI is the space between the superior margin of the subscapularis tendon and the anterior margin of the SS tendon [Figure 10]. The boundaries of the RI are formed by the fusion of the fibers of the joint capsule, subscapularis tendon, and the SS tendon. The contents of the RI include the LHBT, coraco-HL, and the superior gleno-HL.
Figure 10: The rotator interval (area demarked by a blue line) is a focal discontinuity in the rotator-cuff between the anterior margin of the supraspinatus tendon and the cephalad fibers of the subscapularis tendon. The long head of biceps tendon-blue exits the glenohumeral joint through the rotator interval. The black rectangle (dashed lines) demonstrates the probe orientation to visualize the rotator interval adequately. AC: Acromion, Cla: Clavicle, GT: Greater tuberosity, LT: Lesser tuberosity, C: Coracoid

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It is evaluated from the anterior aspect using the modified crass maneuver as described above [Figure 11].
Figure 11: On the short axis (obtained in the modified crass position), the rotator interval is seen as a defect in the rotator-cuff between the anterior edge of the Supraspinatus tendon (broad arrow) and the cephalad fibers of the subscapularis tendon (thin arrow). The superior boundary (curved arrows) is seen as a thin echogenic linear structure

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  Subacromial-Subdeltoid Bursa Top


Although many bursae have been described around the shoulder, the subacromial-subdeltoid (SASD) bursa is the most clinically significant one. The SASD bursa lies deep to the deltoid muscle and the AC joint [Figure 12]. Laterally, it extends beyond the rotator-cuff insertion and curves around the GT. There is no communication of the SASD bursa with the glenohumeral joint.
Figure 12: The subacromial-subdeltoid bursa lies between the rotator-cuff tendon below and the acromion and the deltoid muscle above. The bursa extends beyond the greater tuberosity and curves inferiorly

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Normally, the SASD bursa is visualized as an echogenic stripe [Figure 7] due to the peribursal fat, not more than 2 mm in thickness.[6] When inflamed, the SASD bursa is seen as a hypoechoic structure situated between the deltoid muscle and the rotator-cuff tendon.


  Posterior Joint Recess Top


The posterior joint recess is evaluated from the posterior aspect. Maintaining the arm in the neutral position, the probe is placed transversely across the joint line and scanning is performed in the craniocaudal direction. The axillary pouch is seen below the level of the humeral head. The posterior labrum is seen as an echogenic triangular structure [Figure 13].
Figure 13: The postero-superior glenoid labrum and the posterior joint recess by identifying the glenohumeral joint line from the posterior aspect. The glenoid labrum is seen as an echogenic triangular structure (curved arrows). The humeral cortex lies immediately below it (dashed line). The spinoglenoid notch is seen medial to the glenohumeral joint (arrows). The infraspinatus tendon passes just above the labrum. Infra: Infraspinatus

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  Acromioclavicular Joint Top


The (AC) joint may be evaluated either from the anterior aspect or the posterior aspect. After, palpating the AC joint, the probe is placed horizontally over it. If the AC joint is not palpable, the lateral margin of the acromion is identified, and the probe is slid medially till the joint is reached.

The normal AC joint has smooth articular cortical margins. The AC joint capsule is seen as a hypoechoic convex structure overlying the joint cavity [Figure 14].
Figure 14: The acromioclavicular joint space is identified between the acromion on the lateral aspect and the clavicle medially. The articular surfaces have a smooth echogenic surface. The joint capsule is seen as a smooth hypoechoic structure (arrows)

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  Conclusion Top


US is an excellent modality to evaluate the various pathologies involving the periarticular soft tissues of the shoulder joint. The key periarticular structures include the rotator cuff, SASD bursa, extraarticular LHBT tendon, and the RI and the AC joint. Thorough knowledge of the complex anatomy of the shoulder joint and familiarity with the normal US appearance of the various periarticular structures aids in performing a successful US examination and increases the confidence of the individual performing the examination.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
DePalma AF. The classic. Surgical anatomy of the rotator cuff and the natural history of degenerative periarthritis. Clin Orthop Relat Res 2008;466:543-51.  Back to cited text no. 1
    
2.
Ide J, Tokiyoshi A, Hirose J, Mizuta H. An anatomic study of the subscapularis insertion to the humerus: The subscapularis footprint. Arthroscopy 2008;24:749-53.  Back to cited text no. 2
    
3.
Mochizuki T, Sugaya H, Uomizu M, Maeda K, Matsuki K, Sekiya I, et al. Humeral insertion of the supraspinatus and infraspinatus. New anatomical findings regarding the footprint of the rotator cuff. J Bone Joint Surg Am 2008;90:962-9.  Back to cited text no. 3
    
4.
Martinoli C. Musculoskeletal ultrasound: Technical guidelines. Insights Imaging 2010;1:99-141.  Back to cited text no. 4
    
5.
Petranova T, Vlad V, Porta F, Radunovic G, Micu MC, Nestorova R, et al. Ultrasound of the shoulder. Med Ultrason 2012;14:133-40.  Back to cited text no. 5
    
6.
Daenen B, Houben G, Bauduin E, Lu KV, Meulemans JL. Ultrasound of the shoulder. JBR BTR 2007;90:325-37.  Back to cited text no. 6
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14]



 

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  In this article
Abstract
Introduction
Long Head of Bic...
Rotator-Cuff
Rotator Interval
Subacromial-Subd...
Posterior Joint ...
Acromioclavicula...
Conclusion
References
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