Distal Biceps Tendon Repair

Indication. Surgical repair of a distal biceps tendon rupture is offered to an active patient who wants to recover full supination and flexion strength — most often a complete acute avulsion in a middle-aged man after an eccentric load (a sudden extension force against a contracting biceps). The aim is to re-anchor the tendon to the radial tuberosity and recover the 30 to 40 percent of supination strength (and 10 to 20 percent of flexion strength) lost to a complete rupture. Optimal timing is within 3 to 4 weeks; after that the tendon retracts and shortens, primary repair becomes harder, and a graft may be required. Absolute indications:

• Complete distal biceps tendon rupture in an active patient needing full supination and flexion strength.
• An acute rupture (less than 4 weeks is the optimal window for primary repair).
• A partial tear that has failed non-operative treatment. Relative indications:
• A partial tear involving greater than 50 percent of the footprint that has failed conservative treatment.
• A high-demand athlete or manual worker.
• A chronic rupture in an otherwise active, motivated patient (where graft reconstruction is planned). When not to operate. Non-operative management is reasonable for the elderly or sedentary patient who accepts the strength loss, the low-demand patient content with 30 to 40 percent supination weakness, or anyone in whom significant comorbidity makes the surgical risk unreasonable. Contraindication. Active infection, or a patient who cannot comply with the rehabilitation protocol, are absolute contraindications. Relative contraindications are a chronic rupture (greater than 6 to 8 weeks) with marked retraction (which usually dictates graft reconstruction rather than simple repair), heavy smoking, or uncontrolled diabetes and vascular disease that raise the complication rate. The two-incision technique is specifically avoided where there is a prior ulnar fracture or hardware, a history of heterotopic ossification, or other synostosis risk factors. The one decision that matters: single anterior or two-incision. Every technique ends with the tendon secured to the radial tuberosity; the real choice is how you get there:

Pre-operative assessment. The diagnosis is clinical. The hook test (O'Driscoll) is the single most reliable bedside test: with the elbow at 90 degrees and the forearm actively supinated, the examiner hooks the index finger laterally under the cord-like biceps tendon; if no tendon can be hooked, it is a complete avulsion (reported 100 percent sensitivity and 100 percent specificity, exceeding MRI). The biceps squeeze test (Ruland) is supportive — squeezing the muscle belly produces passive forearm supination when the tendon is in continuity, and its absence suggests rupture. Look also for a palpable defect in the antecubital fossa and proximal retraction of the muscle belly. Imaging confirms rather than diagnoses. Plain films exclude a rare avulsion fracture; MRI confirms complete versus partial rupture, measures retraction and assesses tendon quality; ultrasound offers a dynamic view of retraction with elbow flexion. Counsel the patient on the approach options and on the specific complications — nerve injury (chiefly LABCN), heterotopic ossification, proximal radioulnar synostosis and re-rupture — and set the expectation of 95 percent or better good-to-excellent outcomes for acute repairs. Setup. Supine with the arm on an arm board and the forearm supinated; an upper-arm tourniquet for a bloodless field (a forearm tourniquet is an alternative if you need to judge tendon excursion). Have the cortical-button set (EndoButton or BicepsButton), a cannulated drill, high-strength suture (FiberWire or FiberLoop), a whipstitch needle and a rongeur or burr for tuberosity preparation ready. Fluoroscopy is optional for confirming button position.

The goal is to retrieve the retracted tendon, prepare it, and re-anchor it to the radial tuberosity — protecting the lateral antebrachial cutaneous nerve (LABCN) throughout, and protecting the posterior interosseous nerve (PIN) by keeping the forearm fully supinated during all tuberosity work. The exposure below is the single anterior (modified Boyd-Anderson) approach, the dominant technique; the two-incision variant follows.

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Surgical anatomy in the field. The tendon inserts on the ulnar (posterior) aspect of the radial tuberosity across a footprint of roughly 22 mm by 11 mm (the short head inserts slightly more distally, the long head more proximally). It is the forearm's most powerful supinator and a secondary elbow flexor — hence the 30 to 40 percent supination and 10 to 20 percent flexion loss when it avulses. The structures at risk define the whole operation:

Rehabilitation progresses in phases — the cortical button's biomechanical strength is what permits early motion. | Phase | Timing | Immobilisation | Therapy focus | |-------|--------|----------------|---------------| | Immediate | 0 to 2 weeks | Posterior splint, elbow at 90 degrees, forearm neutral to slight supination | Finger and wrist range of motion only | | Early | 2 to 6 weeks | Removable splint | Passive extension and active flexion out of the splint; avoid terminal extension beyond about 30 degrees; NO resisted supination | | Intermediate | 6 to 12 weeks | Splint for heavy tasks only | Isometric then light resisted strengthening; full range of motion; concentric then eccentric loading; sport-specific work begins | | Return to activity | 12 to 16 weeks and beyond | None | Graded return to function | - Light desk work: 2 to 4 weeks.

• Light manual work: 6 to 8 weeks.
• Heavy manual work: 12 to 16 weeks.
• Full sport: 4 to 6 months. Expected outcome is 95 percent or better satisfaction with near-normal strength for acute repairs. Complications

Nerve injury in more detail. The LABCN is the most commonly injured structure — an incidence of roughly 10 to 25 percent transient and 1 to 5 percent permanent, presenting as lateral forearm numbness and usually resolving with observation. PIN injury is far rarer (1 to 3 percent): it presents as finger and thumb extension weakness with preserved wrist extension (ECRL and ECRB are supplied more proximally), is protected by supination, and again most recover with observation.

Epidemiology and mechanism. A distal biceps rupture typically occurs in an active, middle-aged patient under an eccentric load — a sudden extension force against a contracting, flexed-supinated biceps, felt as the classic 'pop' in the antecubital fossa. Complete avulsion produces the strength deficit that defines the condition: about 30 to 40 percent of supination and 10 to 20 percent of flexion, because the biceps is the forearm's most powerful supinator and a secondary elbow flexor. A partial tear produces a lesser, activity-related deficit. Classification by timing. The practical classification that drives management is time from injury, because the tendon retracts and stiffens: