Acute Anterocentral Elbow Pop and Pain: Distal Biceps Tendon Rupture
The most likely diagnosis is a distal biceps tendon rupture, and initial management should begin with plain radiographs followed by MRI without contrast for definitive diagnosis and surgical planning. 1
Initial Diagnostic Approach
Obtain plain radiographs (AP, lateral, and oblique views) immediately to exclude fractures, dislocations, or avulsion injuries that may accompany the soft tissue injury. 1 This is the mandatory first imaging study per ACR guidelines, even when soft tissue pathology is strongly suspected. 2
Clinical Presentation Specifics
- An audible "pop" in the anterocentral elbow with acute pain is highly characteristic of distal biceps tendon rupture 1
- Look for ecchymosis in the antecubital fossa, a palpable gap in the tendon, and weakness with elbow flexion and forearm supination 1
- The "hook test" (inability to hook your finger under the intact biceps tendon with the elbow flexed 90 degrees and forearm supinated) is highly specific for complete rupture 1
Advanced Imaging for Soft Tissue Injury
If radiographs are normal or indeterminate and soft tissue injury is suspected, MRI without contrast is the appropriate next imaging study. 1 MRI demonstrates superior sensitivity for detecting both complete and partial distal biceps tendon tears compared to ultrasound. 1
MRI Advantages and Technique
- MRI has 86.4% accuracy for detecting complete distal biceps tendon ruptures 1
- Consider adding FABS (flexion-abduction-supination) sequences for challenging cases, particularly when differentiating high-grade partial from complete tears, as this view can identify subtle residual tendon fibers 1
- MRI is particularly useful because partial rupture of the long head with intact short head is the most common injury pattern (77 patients studied) 1
- Traumatic ruptures have significantly higher association with short head involvement compared to atraumatic ruptures 1
Ultrasound Considerations
- Ultrasound can be used as an alternative to MRI for complete tears, with 100% US-surgical correlation demonstrated in acute closed elbow injuries 1
- However, ultrasound is at a significant disadvantage for detecting partial tears and tendinopathy (45.5% accuracy vs 86.4% for MRI) 1
- Dynamic ultrasound may detect pathology missed on static imaging with 96% sensitivity if clinical suspicion remains high 3
Initial Treatment Protocol
Conservative Management (First 0-4 Weeks)
- Sling immobilization for comfort in the acute phase 4
- Ice application for 10 minutes through a wet towel for short-term pain relief 4
- Oral or topical NSAIDs for pain control 3, 4
- Relative rest and activity modification to prevent further damage 3, 4
Critical Decision Point: Surgical vs Conservative
Complete distal biceps tendon ruptures typically require surgical repair, particularly in active individuals and manual laborers. 1 The decision hinges on:
- Degree of tear (complete vs partial) identified on MRI 1
- Patient's functional demands and occupation 1
- Timing of presentation (acute repairs have better outcomes) 1
Common Pitfalls to Avoid
- Do not rely on ultrasound alone for initial evaluation - it misses 54.5% of complete tears and has poor sensitivity for partial tears 1
- Do not skip radiographs even with obvious soft tissue injury, as associated fractures (radial head, coronoid) occur and alter management 1, 2
- Do not delay MRI if surgical intervention is being considered - accurate preoperative assessment of tear pattern (long head vs short head involvement) is essential for surgical planning 1
- Static imaging may miss dynamic pathology; if symptoms persist despite negative MRI, consider dynamic ultrasound or stress fluoroscopy 3