Distal Biceps Tendon Rupture

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The distal biceps tendon attaches the biceps muscle to the radial tuberosity at the elbow, providing the primary force for forearm supination and a secondary contribution to elbow flexion. Complete ruptures most commonly occur in men in their 40s–50s during an unexpected eccentric load — resisting a sudden force with the elbow at 90°. A "pop" is felt, followed by anterior elbow pain, ecchymosis, and a proximal migration of the biceps muscle ("reverse Popeye" appearance).

Unlike long head biceps ruptures at the shoulder (which are largely benign), distal biceps ruptures cause significant (30–40%) loss of supination strength and should be repaired promptly for full functional recovery.

Anterior elbow pain and ecchymosis after a sudden eccentric load. The hook test — the examiner's finger cannot hook under the intact biceps tendon in the antecubital fossa — is pathognomonic for complete rupture. MRI confirms complete vs. partial tear and measures retraction.

Primary repair within 2–3 weeks of injury is recommended for most active patients to restore full supination strength. Delayed repair is more technically complex.

External patient-education references and related OSI pages for additional background:

• Britannica — Tendon
• Britannica — Joint (anatomy)
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language