Distal Biceps Tendon Rupture

Distal biceps tendon rupture is an uncommon, time-sensitive injury in which the biceps tendon avulses from the radial tuberosity, usually in a middle-aged active man lifting or catching a heavy load.

Diagnosis is clinical, and the hook test is the most useful bedside test. Early specialist referral matters for active patients, because primary repair is most straightforward in the first few weeks. Non-operative care is reasonable for low-demand or high-risk patients, accepting reduced supination strength and endurance.

The 2 heads of biceps form a single distal tendon that inserts on the bicipital (radial) tuberosity. The lacertus fibrosus (bicipital aponeurosis) fans medially into the forearm fascia.

Biceps is the main forearm supinator and also flexes the elbow. Brachialis, the primary elbow flexor, largely compensates for lost flexion after rupture, but nothing replaces biceps as a supinator, so supination strength and endurance carry most of the deficit.

Mechanism and risk:

• •Sudden eccentric load on a flexed, supinated elbow, typically in the dominant arm
• •The tendon usually avulses from the tuberosity rather than tearing mid-substance; degeneration in a relatively hypovascular zone just proximal to the insertion predisposes
• •Risk factors: men aged 40 to 60, heavy manual work or weight training, smoking, anabolic steroid use and fluoroquinolone exposure

Injury patterns: complete rupture, partial tear (anterior elbow pain without full retraction) and chronic rupture, where the muscle retracts and scars.