What are the symptoms and investigations for a bicep (biceps brachii) tear?

Biceps Tear: Clinical Presentation and Diagnostic Workup

Clinical Symptoms

A biceps tendon tear presents with acute pain in the antecubital fossa (for distal tears) or anterior shoulder (for proximal tears), accompanied by a palpable/visible deformity of the muscle belly, weakness in elbow flexion and forearm supination, and a positive hook test in complete distal tears. 1

Complete Distal Biceps Tears

• Acute tearing sensation in the antecubital region when unexpected extension force is applied to a flexed arm 1
• Palpable and visible deformity of the distal biceps muscle belly with proximal retraction 1
• Weakness in both elbow flexion and forearm supination (supination weakness is particularly characteristic) 1
• Positive hook test: inability to "hook" the intact tendon with the examiner's finger in the antecubital fossa 1
• Localized tenderness and swelling in the antecubital fossa 2

Partial Distal Biceps Tears

• More subtle presentation that can be diagnostically challenging 2
• Tendon remains palpable in the antecubital fossa, which can lead to missed diagnosis 3
• Positive TILT sign: tenderness over the radial aspect of the radial tuberosity only in full forearm pronation (100% sensitive for partial tears) 2
• Pain with resisted supination and flexion, but less dramatic weakness than complete tears 2

Proximal Long Head Biceps Tears

• Anterior shoulder pain with activity 4
• "Popeye deformity": bulging of the biceps muscle belly in the mid-arm 4
• Often associated with rotator cuff pathology 4

Diagnostic Investigations

Initial Imaging

Plain radiographs should be obtained first to exclude fractures and identify hypertrophic bone formation at the radial tuberosity, which may indicate chronic tendon degeneration 5, 1

Definitive Imaging: MRI is Superior

MRI without contrast is the gold standard imaging modality for biceps tendon tears, with 86.4% accuracy for complete distal tears compared to ultrasound's 45.5% accuracy, and is essential for distinguishing partial from complete tears. 6, 5, 7

MRI Performance Characteristics

• Complete distal tears: 92.4% sensitivity, 100% specificity 5
• Partial distal tears: 59.1% sensitivity, 100% specificity 5
• Overall accuracy: 80.6% for all biceps tendon injuries 7
• Sensitivity/specificity: 76% and 50% respectively for differentiating tear types 7

MRI Technical Considerations

• FABS view (flexion-abduction-supination) should be specifically requested for optimal distal biceps visualization 4, 6, 5
• Axial images are more valuable than sagittal for accurately grading distal biceps tendon injury preoperatively 8
• MRI demonstrates soft tissue abnormalities including tendinosis, partial tears, and complete tears with high accuracy 4
• 100% agreement between MRI and surgical findings has been demonstrated 8

Alternative Imaging: Ultrasound

Ultrasound can be considered only when MRI is contraindicated, but has significant limitations in accuracy, particularly for partial tears and tendinopathy. 4, 6, 3

Ultrasound Performance

• Complete tears: 95% sensitivity but only 71% specificity 5
• Partial tears: significantly lower accuracy than MRI (66.7% vs 66.7% equal, but overall diagnostic confidence lower) 4, 7
• Overall sensitivity/specificity: 62.5% and 20% respectively 4, 7
• Medial imaging approach preferred by radiologists with substantial interreader agreement 4
• Posterior approach with forearm pronated brings the radial tuberosity and distal insertion into view 9

When Ultrasound May Be Appropriate

• MRI contraindications (pacemaker, severe claustrophobia, metallic implants) 4
• Local ultrasound expertise available 4
• Can include therapeutic injection if clinically warranted 4

For Proximal/Long Head Biceps Pathology

MRI shoulder without contrast and ultrasound are rated equally appropriate (rating 9/9) by the American College of Radiology for suspected long head biceps tenosynovitis or tears. 4

Critical Diagnostic Pitfalls to Avoid

• Do not rely on clinical examination alone for partial tears, as the tendon remains palpable and can be misleading 3
• Do not use ultrasound as primary imaging when MRI is available, given its 45.5% accuracy for complete tears and poor performance with partial tears 6, 3, 7
• Do not skip the FABS view on MRI for distal biceps evaluation, as it provides optimal visualization 4, 6
• Do not assume a palpable tendon excludes significant injury, as partial tears can present with intact palpable tissue 3, 2
• Maintain low threshold for MRI if ultrasound is noncontributory, especially when surgical planning depends on distinguishing partial from complete tears 5

Impact on Treatment Planning

MRI facilitates superior surgical planning by accurately differentiating partial from complete tears (critical for determining operative vs. conservative management) and identifying associated injuries including rotator cuff tears. 5, 8

• MRI findings changed clinical treatment plans in 38% of patients in one surgical series 8
• Tears >50% thickness require surgical repair due to high failure rates with conservative management 3
• Tears <50% thickness may be managed conservatively with eccentric strengthening and activity modification 3