Distal biceps tendon rupture

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.

Early primary repair — performed in the acute window before the tendon scars and retracts — is recommended for most active patients to restore full supination strength. Delayed repair, once the tendon has retracted and adhered, 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