What is the recommended diagnostic approach and treatment plan for a suspected bicep injury in an adult patient with no significant medical history?

MRI for Suspected Bicep Injury

For a suspected bicep tendon injury, obtain plain radiographs first to exclude fractures, then proceed directly to MRI without contrast, which is the most accurate imaging modality with 92.4% sensitivity and 100% specificity for complete distal biceps ruptures. 1

Diagnostic Algorithm

Step 1: Initial Imaging

• Plain radiographs are mandatory first to rule out associated fractures or bony abnormalities before proceeding to advanced imaging 2, 3
• Obtain standard views including anteroposterior (AP) in internal and external rotation, plus axillary or scapular-Y view for shoulder biceps injuries 2

Step 2: Advanced Imaging - MRI is Superior

• MRI without contrast is the definitive next study with accuracy of 86.4% compared to ultrasound's 45.5% for complete distal biceps tears 2, 4
• For distal biceps evaluation, use the FABS (flexion-abduction-supination) view with the patient prone, elbow flexed at 90°, shoulder abducted, and forearm supinated for optimal visualization of the entire tendon 2, 3
• MRI demonstrates sensitivity of 92.4% and specificity of 100% for complete distal biceps ruptures, and 59.1% sensitivity with 100% specificity for partial tears 1
• MRI is critical for distinguishing partial from complete tears, which fundamentally changes management 2, 3

When to Consider MR Arthrography

• MR arthrography adds no additional value for biceps tendon tears or chronic epicondylalgia compared to standard MRI 1
• Reserve MR arthrography only for post-surgical evaluation or when distinction between full-thickness and partial-thickness tears remains unclear on standard MRI 2
• For shoulder biceps injuries with suspected associated pathology (rotator cuff tears, SLAP lesions, pulley lesions), MR arthrography provides superior assessment of intra-articular pathology 2

Ultrasound: Limited Role

• Ultrasound should only be considered when MRI is contraindicated, not as a first-line alternative 2, 3
• While ultrasound shows 95% sensitivity for complete versus partial distal biceps tears, it has only 71% specificity and 91% accuracy—significantly inferior to MRI 1
• Ultrasound has substantial limitations in detecting partial tears and tendinopathy 2, 3
• Advanced ultrasound techniques (sonoelastography, superb microvascular imaging) show promise but are not yet standard of care 1

Critical Distinctions That Impact Management

Proximal vs. Distal Tears

• Proximal (long head) biceps tears are more common than distal tears 4
• Partial rupture of the long head with intact short head represents the most common injury pattern 4
• Traumatic ruptures have higher association with short head involvement, while atraumatic ruptures involve the long head in 89% of cases 4

Partial vs. Complete Tears

• Tears <50% may be managed conservatively or with surgical debridement 5
• Tears >50% require division of remaining tendon and surgical repair of the entire unit 5
• Complete ruptures in athletes require surgical repair to avoid profound disability 6, 7
• Nonoperative management typically results in loss of flexion and supination strength and endurance 8

Common Pitfalls to Avoid

• Never rely solely on ultrasound for diagnosis—its accuracy limitations can miss partial tears that require different management 2, 3
• Do not skip plain radiographs—missing an associated fracture changes the entire treatment approach 2, 3
• Do not order MR arthrography routinely—it provides no additional benefit over standard MRI for biceps tendon evaluation 1
• Failing to use FABS positioning for distal biceps MRI reduces visualization quality and diagnostic accuracy 2, 3

Clinical Context

• Patients typically present with antecubital fossa pain, palpable defect, and weakness in flexion/supination 3, 8
• Physical examination findings include well-localized tenderness and positive biceps squeeze test or hook test 3, 8
• This is not an emergent condition but requires timely diagnosis and management to prevent long-term functional loss 4
• Early anatomic reattachment is the surgical goal when indicated 8