What motions increase the risk of tearing the distal biceps tendon?

Motions That Increase Risk of Distal Biceps Tendon Tears

Eccentric contraction of the flexed elbow, particularly during forced extension, is the primary motion that puts you at risk for tearing the distal biceps tendon. 1, 2, 3

Mechanism of Injury

• Sudden, forced eccentric contraction (lengthening while contracting) of the biceps muscle is the most common mechanism of distal biceps tendon tears 4, 1
• This typically occurs when an unexpected extension force is applied to a contracting biceps muscle 1, 3
• Most commonly affects the dominant arm of middle-aged men between 40-60 years of age 1, 2

High-Risk Activities and Motions

• Resisting a heavy load while the elbow is being forced from flexion into extension 2
• Lifting heavy objects, particularly with sudden or unexpected increases in weight 3
• Activities requiring powerful supination (rotating the forearm from palm-down to palm-up) against resistance 2, 3
• Activities requiring forceful elbow flexion against resistance 2

Risk Factors That Increase Vulnerability

• Pre-existing degenerative changes in the tendon 2
• Decreased vascularity in the tendon 2
• Tendon impingement at the radial tuberosity 2
• Middle age (40-49 years) represents the highest risk demographic 2

Clinical Presentation

• Patients typically experience a sudden, sharp, painful tearing sensation in the antecubital fossa (front of elbow) 3
• A palpable defect is often present, which becomes more pronounced with elbow flexion 1
• Pain is initially present during activity but may subside after a warm-up period; it gradually increases in intensity and duration as the condition progresses 5
• Physical examination may reveal localized tenderness that reproduces the patient's pain 5

Diagnostic Considerations

• MRI without contrast is the preferred imaging study with superior accuracy (86.4%) compared to ultrasound (45.5%) for diagnosing distal biceps tendon tears 6, 7
• The FABS (flexion-abduction-supination) view on MRI provides optimal visualization of the distal biceps tendon 6, 5
• Physical examination tests including the hook test, passive forearm pronation test, biceps crease interval test, and bicipital aponeurosis flex test can help with accurate diagnosis 4

Prevention Strategies

• Avoid sudden, unexpected loading of the biceps tendon 1, 2
• Proper warm-up before activities requiring significant elbow flexion or forearm supination 5
• Progressive strengthening to improve tendon tolerance to load 5