Shoulder Ultrasound Anatomy and Indications

Shoulder Ultrasound

Indications

• Evaluation of rotator cuff tendons and muscles
• Assessment of joint fluid and bursae
• Guidance for injections and aspirations
• Diagnosis of shoulder impingement and tendinopathy

Anatomy

• Rotator cuff: supraspinatus, infraspinatus, teres minor, and subscapularis tendons
• Bursae: subacromial-subdeltoid bursa and subscapular bursa
• Joints: glenohumeral joint and acromioclavicular joint

Scanning Techniques

• Transducer: high-frequency linear transducer (7-12 MHz)
• Scanning positions: patient seated or standing with arm relaxed or abducted
• Scanning planes: longitudinal and transverse planes

Normal Ultrasound Findings

• Rotator cuff tendons: homogeneous, fibrillar pattern with clear margins
• Bursae: anechoic or hypoechoic fluid-filled spaces
• Joints: smooth, congruent articular surfaces

Pathological Ultrasound Findings

• Rotator cuff tendons: tendinosis (hypoechoic, heterogeneous), tears (discontinuity, retraction), or calcifications
• Bursae: fluid accumulation or thickening
• Joints: joint effusion, synovitis, or osteophytes

Diagnostic Accuracy

• High sensitivity and specificity for rotator cuff tears and tendinopathy
• Equivalent or superior to MRI for certain shoulder pathologies

Limitations

• Operator dependency
• Limited assessment of deeper structures (e.g., glenohumeral joint)
• Artifacts from bone or air interfaces

Shoulder Ultrasound

Indications

• Evaluation of rotator cuff tendons and muscles is a primary indication for shoulder ultrasound
• Assessment of joint fluid and bursae is another key indication
• Guidance for injections and aspirations can be provided with ultrasound
• Diagnosis of shoulder impingement and tendinopathy is an important indication

Anatomy

• Rotator cuff consists of supraspinatus, infraspinatus, teres minor, and subscapularis tendons
• Subacromial-subdeltoid bursa and subscapular bursa are the two main bursae in the shoulder region
• Glenohumeral joint and acromioclavicular joint are the two joints assessed in shoulder ultrasound

Scanning Techniques

• High-frequency linear transducer (7-12 MHz) is used for shoulder ultrasound
• Patient can be seated or standing with arm relaxed or abducted during the scan
• Longitudinal and transverse planes are used for scanning

Normal Ultrasound Findings

• Rotator cuff tendons demonstrate homogeneous, fibrillar pattern with clear margins
• Bursae are anechoic or hypoechoic fluid-filled spaces
• Joints show smooth, congruent articular surfaces

Pathological Ultrasound Findings

• Tendinosis appears as hypoechoic, heterogeneous areas in rotator cuff tendons
• Tears in rotator cuff tendons manifest as discontinuity or retraction
• Calcifications may be seen in rotator cuff tendons
• Bursae may show fluid accumulation or thickening
• Joints may exhibit joint effusion, synovitis, or osteophytes

Diagnostic Accuracy

• Shoulder ultrasound has high sensitivity and specificity for rotator cuff tears and tendinopathy
• Equivalent or superior to MRI for certain shoulder pathologies

Limitations

• Operator dependency is a significant limitation of shoulder ultrasound
• Deeper structures like glenohumeral joint may not be fully assessed
• Artifacts from bone or air interfaces can affect image quality

Shoulder Ultrasound

Indications

• Evaluation of rotator cuff tendons and muscles is an indication for shoulder ultrasound
• Diagnosis of rotator cuff tears, tendinopathy, and calcific tendinitis can be made using shoulder ultrasound
• Shoulder ultrasound is used to assess shoulder impingement and subacromial bursitis
• Guided injections and aspirations are also an indication for shoulder ultrasound

Scanning Technique

• Patient should be seated or standing with arm relaxed by their side during the scan
• A linear transducer with a frequency of 7.5-12 MHz is used for high-resolution imaging
• Scanning is performed in multiple planes, including longitudinal, transverse, and oblique

Anatomy

• Supraspinatus tendon is located on the posterior aspect of the humeral head
• Infraspinatus tendon is located on the posterior aspect of the humeral head, inferior to the supraspinatus tendon
• Teres minor tendon is located on the posterior aspect of the humeral head, inferior to the infraspinatus tendon
• Subscapularis tendon is located on the anterior aspect of the humeral head
• Subacromial-subdeltoid bursa is located between the acromion and humeral head
• Acromioclavicular joint is located between the acromion and clavicle

Pathology

• Full-thickness rotator cuff tears appear as anechoic defects in the tendon
• Partial-thickness rotator cuff tears appear as hypoechoic defects in the tendon
• Rotator cuff tendinopathy appears as thickening and hypoechogenicity of the tendon
• Calcific tendinitis appears as echogenic foci with posterior acoustic shadowing
• Subacromial bursitis appears as fluid and/or echogenic material within the bursa

Pitfalls and Limitations

• Operator dependence is a pitfall, as technique and image quality depend on operator experience
• Anisotropy can make tendons appear artifactually hypoechoic
• Limited field of view can prevent capture of the entire rotator cuff