Shoulder: Normal and Pathology

Authors

James Mattson MD
Department of Rehabilitation and Human Performance
Department of Emergency Medicine
Mount Sinai School of Medicine

Summary

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Introduction

• Shoulder pain is a common chief complaint in seeking medical attention, accounting for 8-12% of athletic injuries. The shoulder joint has the largest range of motion of any appendicular joint, and as a result has inherent instability, accounting for 50% of joint dislocations presenting to the emergency room.^[1]Bengtzen RR, Daya MR. Shoulder. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 9th editio. ; 2018:549-568. … Continue reading^[2]Stelter J, Malik S, Chiampas G. The Emergent Evaluation and Treatment of Shoulder, Clavicle, and Humerus Injuries. Emerg Med Clin North Am. 2020;38(1):103-124. doi:10.1016/j.emc.2019.09.006
  
• While X-rays are often the first-line diagnostic imaging for shoulder pain, bedside ultrasonography is emerging as a useful diagnostic tool in select conditions, including both osseous and soft tissue injuries.
• Bedside ultrasound has the additional advantage of allowing for dynamic visualization of structures. This assists in evaluation of shoulder mechanics and diagnosis of some specific etiologies of shoulder pain, particularly for soft tissue disorders.^[3]C BSM. Shoulder. In: Baert A, Knauth M, Sartor K, eds. Utrasound of the Musculoskeletal System. Springer; 2007:189-332.^[4]Corazza A, Orlandi D, Fabbro E, et al. Dynamic high-resolution ultrasound of the shoulder: How we do it. Eur J Radiol. 2015;84(2):266-277. doi:10.1016/j.ejrad.2014.11.007
  ^[5]Levine BD, Motamedi K, Seeger LL. Imaging of the shoulder: A comparison of MRI and ultrasound. Curr Sports Med Rep. 2012;11(5):239-243. doi:10.1249/JSR.0b013e31826b6baa
• Ultrasound is useful in guided procedures of the shoulder, including aspiration, directed nerve blocks for analgesia, or corticosteroid injection.^[6]Pourcho AM, Colio SW, Hall MM. Ultrasound-Guided Interventional Procedures About the Shoulder: Anatomy, Indications, and Techniques. Phys Med Rehabil Clin N Am. 2016;27(3):555-572. … Continue reading^[7]Strakowski JA, Visco CJ. Diagnostic and therapeutic musculoskeletal ultrasound applications of the shoulder. Muscle and Nerve. 2019;60(1):1-6. doi:10.1002/mus.26505

Ultrasound Transducer and Settings

Patient seated with optimal physician positioning

Patient in neutral position.

• For ultrasound of the shoulder, a high frequency linear transducer 10Hz or higher is generally used. For deeper structures such as the posterior glenoid, occasionally a lower frequency curvilinear transducer is used.^[8]Jacobson JA. Shoulder ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. ; 2018:3-71. doi:10.1016/b978-1-4557-3818-2.00003-3
• Patient positioning
  • The ultrasound examination of the shoulder is best completed with the patient sitting, and the examiner positioned in front or to side of patient. If available, a rotating stool can allow for easy patient positioning during examination.^[9]Finnoff JT, Smith J, Peck ER. Ultrasonography of the shoulder. Phys Med Rehabil Clin N Am. 2010;21(3):481-507. doi:10.1016/j.pmr.2010.04.001
  • The shoulder examination is completed in multiple positions and with dynamic visualization to allow evaluation of relevant structures. Neutral position consists of the patient resting with arm at the side, and hand with palm up in supination and resting on leg. From this position, the arm can be externally rotated for further evaluation of infraspinatus and biceps tendon (PICTURE). Further examination is done with patient in Crass position, which involves patient placing hand behind their back with shoulder internally rotated, or in modified Crass, which involves patient placing hand on ipsilateral hip with elbow directed posteriorly.^[10]Jacobson JA. Shoulder ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. ; 2018:3-71. doi:10.1016/b978-1-4557-3818-2.00003-3
  • Note that depending on patient presentation and degree of discomfort, repositioning the patient for ideal views may not be possible.

Anatomy

• In musculoskeletal ultrasound, diagnostic point-of-care imaging can often be focused based on the presenting complaint and physical examination. This can be done in the shoulder as well, but with caution as pain in the shoulder can often be referred or diffuse.8 A standardized approach to ultrasound is highest yield in complete evaluation of the shoulder, particularly of the rotator cuff.^[11]C BSM. Shoulder. In: Baert A, Knauth M, Sartor K, eds. Utrasound of the Musculoskeletal System. Springer; 2007:189-332.
  

Biceps Brachii anatomy including the long and short tendons.


Illustration of the bicipital groove with the long head of the biceps tendon. The subscapularis is also visualized.^[12]van Deurzen, Derek FP, et al. “Clinical relevance of the anatomy of the long head bicipital groove, an evidence‐based review.” Clinical Anatomy 34.2 (2021): 199-208.

• Anterior – Biceps Tendon and Subscapularis
  • With the patient in neutral position, the primary landmark to identify in the anterior shoulder is the tendon of the long head of the biceps within the bicipital groove. In this orientation the biceps tendon can be visualized in short and long axis in between the lesser and greater tuberosities. In short-axis orientation, the tendon can be scanned over its course proximally where it courses over the humeral head and distally as it travels down the bicipital groove. The tendon is evaluated distally until tendon of the pectoralis major crosses over the biceps tendon to insert on the lateral lip of the bicipital groove. Rotating the transducer 90 degrees will allow visualization of the tendon in long axis.
  • A similar approach is used to visualize subscapularis tendon. With the patient in neutral position, the transducer is placed again over the bicipital groove and lesser tuberosity is centered on the screen. The patient then externally rotates the shoulder to bring the tendon of the subscapularis in to view. In this view, the subscapularis tendon can be seen in long axis, then in short axis after rotating the transducer 90 degrees. In short axis, is normal to see hypoechoic striations representing interfaces between tendon bundles . Visualizing the biceps tendon in short-axis as the patient eternally rotates the shoulder allows for evaluating for possible subluxation of the tendon from the bicipital groove.^[13]C BSM. Shoulder. In: Baert A, Knauth M, Sartor K, eds. Utrasound of the Musculoskeletal System. Springer; 2007:189-332.
    ^[14]Jacobson JA. Shoulder ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. ; 2018:3-71. doi:10.1016/b978-1-4557-3818-2.00003-3^[15]Allen, G. M., and D. J. Wilson. “Ultrasound of the shoulder.” European journal of ultrasound 14.1 (2001): 3-9.

Illustration of the supraspinatus and infraspinatus.^[16]Image courtesy of https://www.sportsinjuryclinic.net/, “Supraspinatus Tear”


Modified-Crass Position (A). Corresponding ultrasound image (B) and schematic drawing (C) show the supraspinatus tendon (SSP) in the long axis with focal thickening of the subacromial bursa (asterisk). Neutral Position (D). Corresponding ultrasound image (E) and schematic drawing (F) show the swollen SSP in the long axis. HH, humeral head; Acr: acromion^[17]Ricci, Vincenzo, and Levent Özçakar. “The Dodo Bird Is Not Extinct: Ultrasound Imaging for Supraspinatus Tendinosis.” American Journal of Physical Medicine & Rehabilitation 98.1 … Continue reading

• Superior – Supraspinatus and Infraspinatus
  • The Crass or modified Crass positions are used to anteriorly rotate the greater tuberosity in order to visualize the insertion of the supraspinatus and infraspinatus. In the modified Crass position the transducer is placed on the anterior shoulder in a transverse orientation in order to visualize the supraspinatus tendon in the long axis (PICTURE). Scanning should continue anteriorly until visualizing the intra-articular portion of the proximal biceps tendon (PICTURE). This allows for full evaluation of the anterior portion supraspinatus tendon. The transducer can be rotated 90° to visualize the tendon in short axis. In this orientation, hypoechoic lines may be seen, as fibers from the tendon descend to insert on the greater tuberosity. Moving the transducer posteriorly will allow for visualization of the infraspinatus, which inserts on the middle facet of the greater tuberosity.^[18]C BSM. Shoulder. In: Baert A, Knauth M, Sartor K, eds. Utrasound of the Musculoskeletal System. Springer; 2007:189-332.
    ^[19]Jacobson JA. Shoulder ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. ; 2018:3-71. doi:10.1016/b978-1-4557-3818-2.00003-3^[20]Allen, G. M., and D. J. Wilson. “Ultrasound of the shoulder.” European journal of ultrasound 14.1 (2001): 3-9.

• Posterior – Infraspinatus, Teres Minor, Posterior Labrum, Genohumeral Joint
  • With the patient in neutral position, place the transducer just inferior to the scapular spine in an oblique axial plan angled superiorly toward the humeral head. In this orientation the central tendon of the infraspinatus can be traced distally to its insertion on the greater tuberosity. This supplements evaluation in the modified Crass position described above. In this long axis orientation the glenohumeral joint and posterior labrum can be visualized.

Overview of the glenoid fossa and related structures. Lateral view of a right glenoid fossa of the scapula showing the articular cartilage in the middle of the glenoid fossa surrounded by the glenoid labrum on its rim. The subscapular bursa is located anterior to the tendon of the long head of biceps brachii (LHB), in close proximity to the superior glenohumeral ligament (SGHL) and middle glenohumeral ligament (MGHL). The inferior glenohumeral ligament can be found inferiorly, highlighting its different segments: the anterior band (A-IGHL), axillary pouch, and the posterior band (P-IGHL).^[21]Dekker, T.J., Aman, Z.S., Peebles, L.A., Storaci, H.W., Chahla, J., Millett, P.J. et al. (2020) Quantitative and qualitative analyses of the glenohumeral ligaments: an anatomic study. American … Continue reading

• • Sliding the transducer medially is necessary to identify the spinoglenoid notch, which is a potential site for a paralabral cyst. The transducer is then moved inferiorly to visualize the teres minor, and then rotated 90 degrees to visualize the tendons in short-axis.

Pathology

Tenosynovitis long head of biceps tendon in short axis.^[22]Image courtesy of ultrasoundcases.info, “Long head of the biceps tenosynovitis”


Posterior view of the glenohumeral joint showing both normal and a joint effusion.^[23]Image courtesy of acepnow.com, “Ultrasound-Guided Glenohumeral Joint Evaluation and Aspiration”

• Biceps Tenosynovitis and Glenohumeral Joint Effusion
  • The tendon sheath of the long head of the biceps brachii tendon is continuous with the glenohumeral joint. Thus, effusion of the glenohumeral joint may often present with sonographic findings similar to biceps tendon tenosynovitis. Differentiating factors include focal tendon sheath distension and localized tenderness in tenosynovitis, in contrast to diffuse anechoic distension that is not sensitive or hyperemic in glenohumeral joint effusion. A joint effusion may also be visualized by distension of the joint capsule when examining the posterior shoulder. Intra-articular loose bodies may also become lodged in the biceps tendon sheath.
  • The posterior shoulder examination can demonstrate a joint effusion and offer a point of ultrasound-guided intraarticular access in the need of diagnostic arthrocentesis.
  • See: Shoulder Joint Arthrocentesis

Hypertrophy and thickening of the biceps tendon in the bicipital groove.^[24]Image courtesy of https://www.ultrasoundcases.info/, “Biceps tendon tendinopathy / tendinosis”


Sonography of bilateral shoulders. (A and B) Transverse view, (C and D) longitudinal view. Red arrow shows absence of biceps tendon within the right bicipital groove (A and C), white arrow shows normal biceps tendon within the left bicipital groove (B and D).^[25]Lim, Chong Hong, Kok An Lee, and Joe Wei Liew. “Popeye’s sign: biceps tendon rupture.” BMJ Case Rep 13.2 (2020): e234205.

• Biceps Tendinosis and Rupture
  • Biceps tendinosis appears as heterogeneity or thickening in the biceps tendon. This usually occurs within 3.5 cm of the proximal origin of the tendon. Rupture of the proximal biceps tendon presents as absence of the biceps tendon within the bicipital groove due to retraction of the tendon distally.

• Biceps Subluxation and Dislocation

• • Dynamic ultrasound is useful in evaluating for biceps tendon dislocation or subluxation. This injury occurs when the biceps tendon dislocates medial to the lesser tubercle over the subscapularis tendon. Recurring subluxation can be observed while passively externally rotating the arm. This has been described as a result of acute injury, chronic attrition, or a rotator cuff tear extending into rotator interval causing disruption of the biceps stabilizing structures.

Medial dislocation of long head biceps tendon is seen from bicipital groove. Biceps tendon is intact.^[26]Case courtesy of Maulik S Patel, Radiopaedia.org, rID: 10973


Short axis view of the supraspinatus tendon demonstrating cortical changes and hypoechoic articular surface defect.^[27]https://theultrasoundsite.co.uk/, “Partial thickness rotator cuff tear: A summary”


Supraspinatus tendon in short axis. There is a fluid filled defect replacing the entire full thickness and entire width of the right supraspinatus suggesting a tear. The defect length or retraction is 30 mm.^[28]Case courtesy of Maulik S Patel, Radiopaedia.org, rID: 17937

• Rotator Cuff Tear
  • Most rotator cuff tears involve the supraspinatus, but can extend posteriorly to the infraspinatus or involve subscapularis. Visualization of the tendons can help diagnose rotator cuff tears or tendinosis. Rotator cuff tears can roughly be differentiated into partial-thickness or full-thickness tears.
  • Visualization of the entire rotator cuff is necessary for full evaluation for tears, particularly for the most commonly injured supraspinatus. This may require multiple patient positions (neutral, external rotation, modified Crass).9^[29]Finnoff JT, Smith J, Peck ER. Ultrasonography of the shoulder. Phys Med Rehabil Clin N Am. 2010;21(3):481-507. doi:10.1016/j.pmr.2010.04.001
  • Ultrasound in a skilled user has similar diagnostic efficacies to MRI in evaluation for rotator cuff injuries.^[30]Zheng F, Wang H, Gong H, Fan H, Zhang K, Du L. Role of ultrasound in the detection of rotator-cuff syndrome: An observational study. Med Sci Monit. 2019;25:5856-5863. doi:10.12659/MSM.915547 However, ultrasound has lower accuracy in diagnosing partial-thickness rotator cuff tears than full-thickness tears.^[31]Mohtasib RS, Alzahrani AM, Asiri YN, Rayes ZF, Alshaalan MA. Accuracy of shoulder ultrasound examination for diagnosis of rotator cuff pathologies: A single-center retrospective study. Ann Saudi Med. … Continue reading^[32]Teng A, Liu F, Zhou D, He T, Chevalier Y, Klar RM. Effectiveness of 3-dimensional shoulder ultrasound in the diagnosis of rotator cuff tears: A meta-analysis. Med (United States). 2018;97(37):1-8. … Continue reading
  • Partial-thickness tears are characterized by anechoic or hypoechoic disruptions in the tendon fibers. These tears can be further characterized as articular-sided, bursa-side or intra-substance. Articular-sided tears are most common, often occurring at the level of the surgical neck of the humerus.
  • A full-thickness tear is characterized by well-defined anechoic or hypoechoic disruptions of the tendon. These may be associated with retraction or atrophy of the proper muscle proximal to the tear, a finding referred as the
    “naked tuberosity sign.” These most commonly occur at the anterior portion of the supraspinatus tendon.
  • Secondary signs of rotator cuff tears may also be visible on ultrasound. These may include cortical irregularities, joint effusion and bursal fluid, or the cartilage interface sign. Cortical irregularity adjacent to a hypoechoic or anechoic irregularity of a tendon may indicate an underlying tear, particularly of chronic nature. A glenohumeral joint effusion, commonly visualized as and anechoic fluid within the biceps tendon sheath as described above, in combination with fluid in the subacromial-subdeltoid bursa has a high likelihood of rotator cuff tear.
  • Differentiating between rotator cuff tendinosis and a tear can be difficult as both may appear hypoechoic. While rotator cuff tears are well-defined and typically homogenous, tendinosis is generally ill-defined and heterogenous. Tears also typically are associated with cortical irregularities, while tendinosis typically is adjacent to smooth cortex.

Calcific deposits are seen in both supraspinatus and infraspinatus tendons. ^[33]Case courtesy of Frank Gaillard, Radiopaedia.org, rID: 7501


Acute subacromial-subdeltoid bursitis: fluid distending the bursa more than 1.5 mm. The tendon fibers are poorly characterized due to anisotropy.^[34]Case courtesy of Bruno Di Muzio, Radiopaedia.org, rID: 22396

• Calcific Tendinosis
  • Calcific tendinosis occurs from calcium hydroxyapatite deposition in the tendon. Supraspinatus is most commonly involved. Though etiology remains unclear, it is generally accepted that calcific tendinosis may be asymptomatic, usually are not associated with concurrent acute rotator cuff tears, and the appearance of calcium deposits may change over time.
  • Ultrasound findings include hyperechoic deposits with posterior acoustic shadowing. Calcifications can form a thick fluid or slurry in 7% of cases, which does not form a significant posterior acoustic shadow but can be differentiated from normal tendon by lacking anisotropy. Angulating the transducer from a perpendicular orientation with tendon causes the tendon to appear more hypoechoic, and this effect is less prominent in cases of calcific tendinosis.

• Subacromial-Subdeltoid Bursitis
  • Fluid can collect in the subacromial-subdeltoid bursa and can be visualized as a 1-2mm anechoic stripe in the plane between the rotator cuff and overlying deltoid muscle and acromion. The presence of hyperemia as indicated by increased signal with power doppler, as well as tenderness in the area are indicative of bursitis.
  • Causes of bursitis most commonly include subacromial impingement or rotator cuff tear. Isolated bursa involvement may beusually associated with underlying systemic inflammatory conditions such as gout, rheumatoid arthritis, infection, or amyloidosis.
    Presence of subacromial-subdeltoid bursitis as well as joint effusion has a high likelihood of underlying rotator cuff injury.

• Adhesive Capsulitis

• • Adhesive capsulitis is largely a clinical diagnosis but may have associated sonographic findings. One potential finding is limitation in sliding of the supraspinatus beneath the acromion with active abduction. There may also be abnormal hypoechogenicitiy and hyperemia at the rotator cuff interval with thickening of the coracohumeral ligament, though this is not a universal finding. Finally, there will often be decreased ability to visualize the subscapularis due to limited external rotation.

Axial section of the normally concave rotator interval showing conspicuous coracohumeral ligament thickening (red double arrow) with a rounded and convex profile (yellow dotted arrows). LHBT long head of the biceps tendon^[35]Stella, Salvatore Massimo, et al. “Ultrasound features of adhesive capsulitis.” Rheumatology and therapy 9.2 (2022): 481-495.


Lesions of the posterior glenoid labrum: A. an irregular, decreased in size labrum (arrows); B. a labrum avulsed and displaced onto the glenoid (arrows); H – head of the humerus, moved backwards in relation to the glenoid (B), ISP – the infraspinatus muscle; joint fluid (*)^[36]Krzyżanowski, Wojciech, and Marta Tarczyńska. “The use of ultrasound in the assessment of the glenoid labrum of the glenohumeral joint. Part II: examples of labral pathologies.” Journal … Continue reading


A well-defined cyst is noted deep to infraspinatus. It abuts the posterior aspect of glenohumeral joint.^[37]Case courtesy of Maulik S Patel, Radiopaedia.org, rID: 12963

• Posterior Glenoid Labrum and Paralabral Cyst
  • The posterior glenoid labrum can be visualized as a hyperechoic triangular structure lateral to glenoid. A well-defined hypoechoic or anechoic cleft may indicate a labral tear.
  • It is important to scan medially along the scapular spine to evaluate for parameniscal cysts, particularly at the spinoglenoid notch and suprascapular notch. Parameniscal cysts can compress the suprascapular nerve cause denervation and atrophy of the infraspinatus muscle when located in the spinoglenoid notch, or of both the infraspinatus and supraspinatus when located in the suprascapular notch. This may demonstrate denervation changes such as muscle atrophy and hyperechogenicity.

https://youtu.be/JR4R9EUiRYMVideo of an anterior shoulder dislocation. The probe is on the posterior shoulder and you can see the humeral head is not articulating with the glenoid cavity. Hemearthrosis is present with a distended capsule.https://youtu.be/9B-Y9H3rbosConfirmation of reduction with the probe on the posterior shoulder. Internal and external rotation of the joint demonstrate appropriate glenohumeral articulation.

• Shoulder Dislocation
  • Evaluation of the posterior glenohumeral joint can provide rapid assessment for shoulder location. This simple evaluation has high sensitivity and specificity and may allow for rapid confirmation of suspected anterior shoulder dislocations.^[38]Boswell B, Farrow R, Rosselli M, et al. Emergency Medicine Resident-Driven Point of Care Ultrasound for Suspected Shoulder Dislocation. South Med J. 2019;112(12):605-609. … Continue reading^[39]Pescatore R, Nyce A. Managing Shoulder Injuries in the Emergency Department: Fracture, Dislocation, and Overuse. Emerg Med Pract. 2018;20(6):1-28.
    
  • Glenohumeral separation distance measures the anterior-posterior displacement of the most posterior aspects of the glenoid fossa and head of humerus, when image obtained from posterior glenohumeral approach. A glenohumeral separation distance >0cm (glenoid measured posterior to humeral head) has a high sensitivity for anterior dislocations.^[40]Lahham S, Becker B, Chiem A, et al. Pilot study to determine accuracy of posterior approach ultrasound for shoulder dislocation by novice sonographers. West J Emerg Med. 2016;17(3):377-382. … Continue reading
  • Point-of-care ultrasound can also be useful in suspected posterior dislocations. This injury is easily missed on anterior-posterior radiographs, and axillary views can be difficult to obtain due to pain and difficulty with abduction. Thus, ultrasound is a useful tool in further evaluation when clinical suspicion is high.^[41]Henneberry R, Dahn T, Atkinson P. Just the Facts: Point-of-care ultrasound in the management of shoulder dislocations. Can J Emerg Med. 2020;22(3):287-290. doi:10.1017/cem.2020.14

• Clavicle Fracture
  • To assess for clavicle fracture with ultrasound, one scans along the length of the clavicle to evaluate for a cortical step-off. This is particularly useful in pediatric evaluations to decrease radiation exposure in diagnostic evaluation.

https://youtu.be/lH8dYp1pWeALong axis ultrasound of the distal 1/3 of the clavicle shows a cortical irregularity with surrounding swelling and fluid (blood).


Abrupt discontinuity of the right bony cortex between the greater tubercle and the rest of the right humerus. Subtle fluid adjacent to the fracture, compared with the left side.^[42]Case courtesy of Maulik S Patel, Radiopaedia.org, rID: 10603

Longitudinal view of a normal appearing acromio-clavicular joint space. The hypoechoic space between the hyperechoic lateral clavicle and the medial edge of the acromion is the acromio-clavicular joint space.^[43]Selame, Lauren Ann J., et al. “A Stepwise Guide to Performing Shoulder Ultrasound: The Acromio-Clavicular Joint, Biceps, Subscapularis, Impingement, Supraspinatus Protocol.” Cureus 13.9 … Continue reading

• Greater Tuberosity Fracture
  • Greater tuberosity fractures appear as a cortical step-off and discontinuity at the junction between the greater tuberosity and humeral articular surface. This is not to be mistaken with cortical irregularities associated with rotator cuff tears which are located focally at the rotator cuff footprint on the greater tuberosity.^[44]Vosti KL, Jacobs CD. Outcome measurement in postgraduate year one of graduates from a medical school with a pass/fail grading system. Acad Med. 1999;74(5):547-549. … Continue reading

• Acromioclavicular Joint Disorders
  • Sonographic findings for pain attributed to acromioclavicular joint arthritis include joint effusion, narrowing of joint space, and osteophytic changes. AC joint dislocation can be visualized as well, with displacement of the distal clavicle from the edge of the acromion.

Shoulder Procedure Chapters

• Shoulder Joint Arthrocentesis
• Acromioclavicular Joint Arthrocentesis
• Sternoclavicular Joint Arthrocentesis
• Shoulder Joint Injections

Pearls and Pitfalls

• Anisotropy is a common artifact that depends on the direction of the ultrasound beam that leads to artificial hypoechoic or anechoic appearance of the tendon when not perpendicular to the tendon. This can be minimized by constantly tilting the angle of the transducer to remain perpendicular to the tendon fibers.19
• The subscapularis is multipennate, which can be mistaken for tendinopathy or tear. It is important to visualize the rotator cuff tendon in two axes to avoid misdiagnosis.19

References