Imaging for Distal Biceps Tendon Tear in the Emergency Room
For a suspected distal biceps tendon tear presenting to the emergency room, ultrasound should be the first-line imaging modality due to its high sensitivity (95%), specificity (71%), and accuracy (91%) for diagnosing complete versus partial tears. 1
Initial Imaging Approach
Standard Radiographs
- Begin with a standard three-view radiographic series:
- Anteroposterior (AP)
- Lateral
- Oblique views
- Purpose: To exclude fractures, dislocations, or avulsion injuries that may require urgent intervention
- May detect avulsion fractures at tendon attachment sites or calcific tendinopathy
Ultrasound Evaluation
- Following normal radiographs, ultrasound is recommended as the preferred next imaging study:
When to Consider Advanced Imaging
MRI Indications
- When ultrasound is inconclusive
- When surgical intervention is being considered
- For better visualization of associated injuries
- For more accurate identification of tear type
MRI Performance
- Overall sensitivity: 92.4% and specificity: 100% for detecting distal biceps tendon ruptures 3
- Complete tears: 100% sensitivity and 82.8% specificity 3
- Partial tears: Lower sensitivity at 59.1% but 100% specificity 3
- FABS position (flexed elbow, abducted shoulder, forearm supinated) improves visualization of the distal biceps tendon 4
Key Diagnostic Features
On Ultrasound
- Complete tear: Discontinuity of tendon, retraction, fluid-filled tendon sheath
- Partial tear: Tendon thickening, hypoechoic areas within tendon, partial discontinuity
On MRI
- Complete tear: Absence of tendon distally, fluid-filled tendon sheath, antecubital fossa mass 5
- Partial tear: High signal intensity within tendon, fluid in biceps tendon sheath, thinning or thickening of distal tendon 5
Common Pitfalls to Avoid
- Inadequate views or improper technique leading to misdiagnosis
- Premature advanced imaging before appropriate radiographs
- Overlooking subtle findings on initial imaging
- Delaying diagnosis, especially for complete tears where early surgical reattachment is recommended for optimal outcomes 6
- Failure to recognize associated injuries that may affect management
Clinical Correlation
- Imaging findings should be correlated with physical examination:
- Visible deformity
- Ecchymosis
- Asymmetry compared to unaffected arm
- Weakness in elbow flexion and forearm supination
Remember that early diagnosis is critical, as complete tears typically require surgical intervention within 2-3 weeks of injury for optimal outcomes 6. Partial tears may be managed conservatively depending on the extent of the tear and patient factors.