Can ultrasound diagnose a ruptured tendon or ligament in the shoulder?

Ultrasound for Shoulder Tendon and Ligament Ruptures

Yes, ultrasound can effectively diagnose ruptured tendons in the shoulder, particularly full-thickness rotator cuff tears and biceps tendon ruptures, with excellent accuracy when performed by experienced operators. 1

Diagnostic Capability

What Ultrasound Can Reliably Detect

Ultrasound is highly effective for evaluating rotator cuff and biceps tendon pathology, with the American College of Radiology rating it as "usually appropriate" (9/9 rating) for rotator cuff assessment. 1, 2

• Full-thickness rotator cuff tears: Ultrasound demonstrates 90-91% sensitivity and 93-95% specificity for complete tears 2
• Biceps tendon ruptures: Ultrasound readily reveals discontinuity of the tendon, which is commonly associated with rotator cuff tears 3
• Long head of biceps pathology: All cases of dislocation or rupture can be diagnosed, though differentiation between the two may be challenging 4

Limitations to Consider

Ultrasound has important limitations that affect diagnostic accuracy:

• Partial-thickness tears: These are difficult to detect on static ultrasonograms and are frequently missed (6 of 7 partial tears overlooked in one study) 4, 3
• Operator dependency: Results are highly dependent on examiner experience and expertise 1
• Deep structures: Limited evaluation of labral tears, capsular structures, and bone marrow pathology 1
• Ligamentous injuries: While ultrasound can visualize ligaments, its reliability for shoulder ligament ruptures is less established compared to tendons 1

Clinical Algorithm for Imaging Selection

When to Use Ultrasound

Ultrasound is the appropriate first-line soft tissue imaging modality when:

• Evaluating suspected full-thickness rotator cuff tears in experienced hands 1, 2
• Assessing biceps tendon pathology 1
• Evaluating postoperative rotator cuff integrity after shoulder replacement 1
• Guiding therapeutic injections or aspirations 1
• Patient has metallic hardware causing MRI artifacts 2

When MRI is Preferred Over Ultrasound

MRI without contrast should be chosen instead when:

• Age < 35 years: MRI/MRA is the modality of choice for instability and labral pathology 1
• Suspected partial-thickness tears: MRI has superior sensitivity for incomplete tendon injuries 1
• Labral or capsular pathology: These deep structures cannot be adequately assessed by ultrasound 1
• Comprehensive soft tissue evaluation needed: MRI provides better visualization of muscle atrophy, fatty infiltration, and bone marrow edema 2

Key Clinical Pearls

Important considerations for optimal diagnostic accuracy:

• Expertise matters critically: Even relatively inexperienced examiners can achieve 84% accuracy for rotator cuff tears, but this requires focused training 4
• Dynamic examination advantage: Ultrasound uniquely allows real-time dynamic evaluation for impingement assessment 5, 6
• Correlation with clinical course: Normal ultrasound findings correlate with recovery in less than 1 week, while pathologic tendon changes predict symptoms lasting at least 1 month 7
• Cost-effectiveness: Ultrasound is relatively inexpensive and widely available compared to MRI 5, 6

Common Pitfalls to Avoid

• Don't rely on ultrasound alone for partial tears: These require MRI or MR arthrography for accurate diagnosis 1, 4
• Don't use ultrasound for suspected labral injuries: MRA is the gold standard for labral pathology 1, 2
• Don't assume all operators are equally skilled: Verify local expertise before relying on ultrasound results 1
• Don't overlook the need for initial radiographs: Plain films should always be obtained first to exclude fractures and dislocations 1, 2