Shoulder ultrasound: current concepts and future perspectives

Abstract

Ultrasonography is an established and effective imaging technique that can be used to evaluate articular and periarticular structures around the shoulder. It has been shown to be useful in a wide range of rotator cuff diseases (e.g. tendon tears, rotator cuff calcific tendinopathy and bursitis) as well as non-rotator cuff abnormalities (instability, synovial joint diseases and nerve entrapment syndrome). A scanning protocol is highly recommended to reduce the rate of operators' errors by following a standardized scheme including a list of main structures. Shoulder ultrasound has several advantages: it is a relatively cheap and widely available technique, free from ionizing radiation, that can reach excellent diagnostic accuracy even compared to magnetic resonance imaging. Moreover, it is the only imaging technique that allows dynamic evaluation of musculoskeletal structures, which is important for the evaluation of impingement. Also, due to the shoulder's superficial anatomical position, ultrasound can also be helpful in guiding interventional percutaneous procedures, both for diagnostic (e.g. magnetic resonance arthrography) and therapeutic purposes (e.g. percutaneous treatment of calcific tendonitis). Contrast-enhanced ultrasound and speckle tracking offer complimentary evaluations of shoulder anatomy and biomechanics. Moreover, the advent of ultra-high-frequency US, with probes up to 70 MHz allowing for a resolution as low as 30 μm, is a promising tool for further evaluation of the shoulder anatomy, and diagnostic and therapeutic strategies.

Keywords: shoulder; sonography; ultrasound.

Fig. 1.

The rotator cuff is composed of four muscles with relative tendons attaching onto the humerus: the subscapularis, the supraspinatus, the infraspinatus, and the teres minor. The long head of the biceps tendon (LHBT) is located in the humeral groove, stabilized by the subscapularis tendon. The subacromial-subdeltoid (SASD) bursa is a large synovial space that lies between the coracoacromial arch and the supraspinatus tendon

Fig. 2.

Full-thickness rupture of the LHBT. Transverse short axis (A) over the bicipital groove shows anechoic effusion and hemorrhage in the synovial sheath (arrow). Sagittal long axis (B) shows large effusion with a thicker sheath wall (arrow). No tendon fibers are recognized at these points, with the muscle belly and the distal stump being retracted inferiorly

Fig. 3.

Partial-thickness supraspinatus tear of the articular surface (white arrows) on the short (A) and long (B) axis, and of the bursal surface (yellow arrows) on the short (C) and long (D) axis. The tear is displayed as a hypoechoic area with loss of normal fibrillar pattern, involving only one side of the tendon. Star: humeral head. Asterisk: greater tuberculum at the supraspinatus footprint

Fig. 4.

Full-thickness tear of supraspinatus insertional fibers (arrow) with fiber retraction (dashed arrow). Star: humeral head. Asterisk: greater tuberculum at the supraspinatus footprint

Fig. 5.

Cartilage interface sign. This represents a curvilinear hyperechoic line that courses parallel to the hypoechoic hyaline cartilage of the humeral head (yellow arrow), located at the interface between the hyaline cartilage and the abnormal hypoechoic tendon. It is a result of increased US transmission due to changes in acoustic impedance in cases of articular surface–sided tendon disease, being more pronounced in cases of full-thickness RC tears. White arrow: full-thickness supraspinatus tear. Star: humeral head. Asterisk: greater tuberculum at the supraspinatus footprint

Fig. 6.

Small pre-insertional intratendinous calcification of the supraspinatus, with acoustic shadowing. Asterisk: footprint of the supraspinatus at the greater tuberosity

Fig. 7.

Long-standing full-thickness supraspinatus tear with a degenerative change of the shoulder and inferior acromioclavicular (AC) joint capsule disruption. Fluid erupts superiorly from the SASD bursa and the glenohumeral joint through the AC interval (white arrow), forming a supraclavicular collection known as the geyser sign (yellow arrows). Star: AC joint

Fig. 8.

Partial dislocation of the AC joint after trauma. US shows widening of the articular space (asterisk) with capsule distension and effusion (arrow). The contralateral normal joint is displayed in the right inferior corner

Fig. 9.

Subcoracoid impingement. A synovial hypertrophic nodule (white arrow) and the coracoid (asterisk) determine impaired sliding of the subscapularis (yellow arrow) during dynamic internal rotation on US scan. A. initial internal rotation. The belly of the suprascapularis is compressed passing under the coracoid. B. with rotation progression, the belly snaps and passes under the coracoid. Star: lesser tuberosity of the humeral head

Fig. 10.

US paralabral cyst (arrows) at the SGN (A), confirmed with MRI arthrography (B). The cyst is located in close proximity to the suprascapular nerve, which may lead to progressive infraspinatus neurogenic muscle atrophy (not affected in this case)