What is the initial test for a suspected bicep (biceps brachii) tear?

Initial Testing for Suspected Biceps Tear

Plain radiographs should be obtained first to rule out fractures and bony abnormalities, followed immediately by MRI without contrast as the definitive diagnostic imaging study. 1, 2, 3

Diagnostic Algorithm

Step 1: Clinical Examination

Before any imaging, perform specific physical examination maneuvers:

• Hook test - The most reliable clinical test for complete distal biceps tears 4
• Passive forearm pronation test - Assesses tendon integrity during rotation 4
• TILT sign - Palpate the radial tuberosity with the forearm in full pronation; tenderness over the lateral aspect indicates partial tear (100% sensitivity reported) 5
• Biceps squeeze test and biceps crease interval test - Additional confirmatory maneuvers 4

Look for the "Popeye deformity" (bulging of biceps muscle belly in mid-arm) which indicates proximal long head tears 3

Step 2: Initial Imaging - Plain Radiographs

Obtain plain X-rays first to exclude:

• Associated fractures 1, 2, 3
• Bony abnormalities 2
• Other skeletal pathology 1

Step 3: Definitive Imaging - MRI Without Contrast

MRI is the gold standard imaging modality with 86.4% accuracy for complete distal biceps tears, compared to ultrasound's 45.5% accuracy. 1, 2, 3

MRI Performance Characteristics:

• Complete tears: 92.4% sensitivity, 100% specificity 3
• Partial tears: 59.1% sensitivity, 100% specificity 3
• Superior for distinguishing partial from complete tears 1, 3

Critical Technical Detail:

Request the FABS view (flexion-abduction-supination) - patient positioned prone with elbow flexed 90°, shoulder abducted, and forearm supinated. This allows visualization of the entire distal biceps tendon on a single image. 1, 2, 3

Step 4: Alternative Imaging - Ultrasound (When MRI Contraindicated)

Ultrasound can be considered only when MRI is unavailable or contraindicated, but has significant limitations:

• Accuracy: 51.6% overall vs. 80.6% for MRI 3
• Complete tears: 95% sensitivity but only 71% specificity 3
• Partial tears: Only 66.7% sensitivity and specificity 3
• Critical caveat: Ultrasound sensitivity is 91% when performed by musculoskeletal radiologists but drops to only 40% when performed by non-specialists 6

The American College of Radiology recommends maintaining a low threshold for proceeding to MRI if ultrasound is noncontributory. 3

Common Pitfalls to Avoid

• Do not rely solely on ultrasound - It frequently misses partial tears and tendinopathy 1, 2
• Do not skip plain radiographs - Missing associated fractures can alter management 1, 2
• Do not accept ultrasound performed by non-specialists - The examination requires specialized musculoskeletal expertise 6
• Do not forget to request FABS view - Standard MRI positioning may miss distal biceps pathology 1, 2

Why MRI Over Ultrasound

MRI provides superior surgical planning by:

• Accurately differentiating partial from complete tears 3, 7
• Identifying associated pathologies (rotator cuff tears, UCL injuries, pulley lesions, SLAP lesions) 1, 3
• Determining extent of tendon involvement (crucial since >50% tears typically require surgery while <50% can be managed conservatively) 7