Distal Biceps Tendon Rupture

History: sudden audible or palpable pop during eccentric loading - classically catching a heavy falling object, a single deadlift, or resisting a heavy weight. Sharp immediate pain, often followed by a deeper ache. Supination weakness. Bruising over the anterior antecubital fossa within 24-48 hours.

Examination:

• •Reverse Popeye deformity: biceps muscle belly pulled proximally. Contrast with standard Popeye of long head rupture, where the muscle drops distally
• •Ecchymosis over the antecubital fossa
• •Hook test (O'Driscoll): elbow flexed to 90 degrees, forearm fully supinated; attempt to hook a finger laterally around the distal biceps tendon. A cord-like tendon is palpable in an intact tendon; inability to hook indicates complete rupture. It is the most useful bedside test, with prospective sensitivity of approximately 96% and specificity of approximately 67%; reduced reliability in partial tears or with intact lacertus fibrosus

• •Biceps squeeze test (Ruland): with the elbow flexed and forearm supinated, squeeze the muscle belly; an intact tendon produces passive forearm supination, a ruptured tendon does not
• •Biceps crease interval (ElMaraghy): the normal distance from the antecubital crease to the distal muscle belly is 4-5 cm. A BCI greater than 6 cm, or a ratio greater than 1.2 versus the contralateral arm, is highly specific for complete rupture
• •Passive forearm pronation test: passive pronation normally shifts the biceps muscle belly distally; in rupture the muscle stays proximal
• •Supination weakness greater than flexion weakness is a key clue

Red flags: open injury; neurovascular compromise; concomitant elbow dislocation that fails reduction; features of compartment syndrome (severe pain out of proportion, tense compartment, pain on passive stretch).

Differentials: long head of biceps tendon rupture (standard Popeye, distal muscle drop, preserved supination strength); brachialis muscle rupture (rare, anterior pain distal to the biceps, preserved supination); distal biceps tendinopathy or partial tear (anterior pain without obvious deformity; tendon thickened in tendinopathy, thinned in partial tear); anterior interosseous nerve syndrome (painless motor loss, positive OK sign collapse); pronator syndrome (median nerve at the elbow); rare bony avulsion of the radial tuberosity.

Clinical examination is usually sufficient to diagnose a complete distal biceps tendon rupture. Imaging is reserved for partial tears, equivocal cases, chronic presentations, and pre-operative planning.

Plain radiographs: first-line in acute injury to exclude an associated fracture (particularly a radial tuberosity avulsion fragment). Usually normal in isolated tendon rupture.

MRI: the preferred cross-sectional imaging investigation. The flexed-abducted-supinated (FABS) view is a specialised protocol with the arm overhead, elbow flexed 90 degrees, forearm supinated; improves visualisation along the distal tendon course. Distinguishes partial from complete tears, grades retraction, and assesses tendon quality for surgical planning.

Ultrasound: a legitimate alternative to MRI in experienced hands, with particular strength as a dynamic assessment - with the patient performing resisted supination, the sonographer can observe tendon gap widening or failure of the distal muscle belly to engage (a definitive diagnostic finding). Operator-dependent; first-line where MSK ultrasound expertise is established.

Primary distal biceps tendon repair is most straightforward in the first few weeks of injury. Delay leads to tendon retraction and scarring, which increases technical difficulty and may require graft reconstruction. Aim for specialist assessment within 1-2 weeks - early referral keeps all surgical options open.

Non-operative management:

• •Appropriate for elderly patients, low-demand lifestyles, non-dominant arm injuries, significant surgical risk, or patient preference
• •Functional outcome: accept substantial loss of supination strength and endurance with some loss of flexion strength; endurance deficits are often more symptomatic than peak strength loss
• •Sling for comfort only in the acute phase; early pain-free range of movement from day 1-3
• •Structured physiotherapy focused on supination endurance, elbow flexion strengthening, and activity modification

Operative management (standard UK approach for active patients):

• •Aim for specialist assessment within 1-2 weeks of injury and early primary repair where indicated
• •Primary repair in the first few weeks allows direct reattachment without a graft
• •Delay increases technical difficulty because of tendon retraction and muscle scarring, and may necessitate reconstruction with an interposition graft (Achilles tendon allograft or semitendinosus autograft); the exact cut-off is not absolute, and delayed primary repair remains possible in selected cases

Surgical approaches:

• •Single-incision anterior approach: direct visualisation of the tuberosity via an antecubital fossa incision. Higher rates of sensory nerve complications, particularly LABC neuropraxia
• •Two-incision (Boyd-Anderson modification) approach: anterior plus posterolateral dorsal incision. The PIN lies close to the posterior dissection and is typically protected by maximal forearm pronation intra-operatively. Higher rates of heterotopic ossification and radioulnar synostosis
• •PIN palsy can occur with EITHER approach and is not a distinguishing feature
• •Fixation options (cortical button / endobutton, suture anchors, interference screws, transosseous tunnels): functional outcomes are broadly similar across techniques

Complications:

• •LABC nerve neuropraxia: the most common complication overall, particularly with single-incision repairs. Usually transient with recovery over weeks to months
• •Heterotopic ossification: associated with the two-incision approach; managed with NSAIDs, active range of movement, occasionally surgical excision
• •Radioulnar synostosis: rare but devastating; abolishes pronation-supination
• •PIN palsy: motor weakness of finger and thumb extension
• •Re-rupture: approximately 1-5%

Referral: urgent shoulder/elbow specialist referral for suspected complete rupture in an active patient, aiming for specialist assessment within 1-2 weeks; routine referral for partial tears with persistent symptoms despite rehabilitation; primary care management for confirmed non-operative candidates (elderly, low-demand, contraindications to surgery).

Typical pathway only. Progression varies by repair tension, surgeon protocol, tissue quality, and job demands. Local protocols and surgeon or physiotherapist advice take precedence.

Non-operative:

• •Sling for comfort 1-2 weeks; early pain-free range of movement from day 1-3
• •Progressive strengthening as symptoms settle
• •Full activity as tolerated; accept a residual deficit in supination and flexion

Post-operative (primary repair):

• •Sling or posterior slab in the early phase (typically 1-2 weeks)
• •Protected passive and active-assisted motion under physiotherapy supervision
• •Many UK protocols begin strengthening from 4-6 weeks, avoiding early resisted supination and elbow flexion to protect the repair
• •Heavier duties and return to manual work or resistance training are introduced later according to specialist advice, typically from 12 weeks onwards but highly variable
• •Return to heavy contact sport or competitive resistance training is individualised, guided by the operating surgeon

Post-operative (reconstruction with graft): broadly similar pathway, progression typically slower, return to unrestricted activity often later.

Modifiable factors: smoking slows tendon-bone healing (advise cessation and signpost NHS Stop Smoking services); strongly advise cessation of anabolic steroid use; address psychosocial factors and graded return-to-work planning. Do not drive while wearing a sling; return to driving only when able to safely control the vehicle and perform an emergency stop.

• •BESS shoulder and elbow guidance hub - The UK framework for distal biceps tendon rupture. Emphasises specialist assessment within 1-2 weeks for active patients and primary repair as the standard surgical approach.
• •O'Driscoll hook test (1995, AJSM) - Original description of the hook test. Subsequent prospective data have refined estimates to approximately 96% sensitivity and 67% specificity, with reduced reliability in partial tears or when the lacertus fibrosus is intact.
• •ElMaraghy biceps crease interval - BCI greater than 6 cm or a ratio greater than 1.2 versus the contralateral arm is highly specific for complete rupture; a useful adjunct when the hook test is equivocal.
• •Single vs two-incision approach - Multiple systematic reviews show comparable functional outcomes. Complication profiles differ: LABC neuropraxia more common with single-incision; heterotopic ossification and radioulnar synostosis more common with two-incision.
• •BOA Standards for Trauma (BOASTs) - Apply to associated open or high-energy trauma; not specific to isolated distal biceps tendon rupture.

• •Classic demographic: middle-aged active man (40-60), dominant arm, manual worker or weightlifter. Mechanism: eccentric load on a flexed supinated elbow (catching a heavy falling object, single heavy deadlift).
• •Hook test (O'Driscoll) is the most useful bedside test for complete rupture (~96% sensitivity, ~67% specificity). Reduced reliability in partial tears or when the lacertus fibrosus is intact.
• •Biceps crease interval (BCI) greater than 6 cm or ratio greater than 1.2 versus contralateral is highly specific for complete rupture. Reverse Popeye = distal biceps rupture; standard Popeye = long head rupture.
• •Supination weakness exceeds flexion weakness because the brachialis compensates for flexion loss but no other muscle replaces the biceps as a supinator.
• •Early specialist referral (within 1-2 weeks) matters because delay makes repair more demanding and may necessitate graft reconstruction. LABC nerve neuropraxia is the most common complication overall, particularly with single-incision anterior repairs.
• •PIN palsy can occur with EITHER surgical approach and is not a distinguishing feature. Anabolic steroid use, smoking, and fluoroquinolone exposure are recognised risk factors.