The distal biceps tendon inserts on the bicipital tuberosity of the radius, transmitting the biceps brachii supination and flexion force. It travels through a fibro-osseous tunnel adjacent to the radial tuberosity where it is susceptible to impingement during repetitive supination. Complete rupture of the distal biceps tendon is the most dramatic biceps tendon injury and produces the characteristic Popeye deformity of a retracted biceps muscle belly with significant loss of supination strength.
Transmits biceps brachii force for elbow flexion and forearm supination
Distal biceps tendon rupture occurs predominantly in men aged 40 to 60 during an eccentric load on the flexed arm, producing an audible pop, antecubital fossa pain, and the characteristic Popeye appearance of the retracted muscle. The hook test, where the examiner hooks a finger under the distal biceps tendon in the antecubital fossa, is the most reliable clinical test, with absence of a cordlike structure being diagnostic of complete rupture. Surgical repair within 3 to 4 weeks produces superior outcomes compared to late or no repair because supination strength loss is approximately 50 percent without surgery.
Complete avulsion of the distal biceps tendon from the radial tuberosity producing the Popeye sign, positive hook test, and significant supination weakness, requiring early surgical repair for best functional outcomes.
Partial thickness degeneration of the tendon within the radial tunnel producing antecubital fossa pain reproduced by resisted supination, managed with load modification and eccentric exercise.
