Distal Biceps Tendon Repair - Comprehensive (Single vs Two-Incision Techniques)

Critical Anatomical Relationships

Radial Tuberosity Anatomy:

• Bicipital tuberosity located on anteromedial proximal radius 2-3cm distal to radial head
• Footprint oval-shaped, 15-20mm length, 8-12mm width in most patients
• Tuberosity rotates: SUPINATION brings anterior/medial (accessible), PRONATION rotates posterior/lateral (inaccessible)
• Separated from ulna by interosseous membrane, thick at this level
• Bicipital bursa normally present between tendon and tuberosity (reduces friction)

Nerve Anatomy - Critical for Safe Surgery:

• LABCN: Terminal sensory branch of musculocutaneous nerve, emerges lateral edge of biceps tendon 5-7cm proximal to crease, pierces brachialis fascia, crosses field obliquely, innervates lateral forearm skin, variable branching (1-5 branches), injured in 15-30% of cases
• PIN: Motor branch from radial nerve bifurcation, enters supinator 3-5cm distal to tuberosity, innervates ECRL, ECRB, supinator before becoming purely motor PIN, supplies finger/thumb extensors, wrist extensors, abductor pollicis longus
• Radial nerve proper: Bifurcates into PIN (deep motor) and superficial radial nerve (sensory) at level of radiocapitellar joint, lies anterior to lateral epicondyle
• Median nerve: Medial structure, 2-3cm from working interval, safe if stay in BR-PT plane

Vascular Anatomy:

• Radial artery: Main vessel at risk, courses between BR and PT, 1-2cm medial to BR muscle belly, gives recurrent radial branch to brachioradialis
• Posterior interosseous artery: Accompanies PIN through supinator, at risk during posterior dissection
• Brachial artery bifurcation: Usually proximal to field but variable

Muscular Intervals:

• BR-PT interval: TRUE internervous plane (radial vs median innervation), this is the working space for single anterior approach
• EDC-ECU interval: Posterior approach internervous plane (radial vs PIN innervation) for two-incision technique

Patient Setup and Positioning

Position: Supine on operating table. Affected arm on radiolucent arm board extended 90° from body OR brought across chest on bolster (allows easier elbow flexion). Ensure adequate shoulder external rotation to access antecubital fossa comfortably.

Tourniquet: Non-sterile tourniquet on proximal arm, inflate to 250-280mmHg. Exsanguinate with elevation (avoid Esmarch wrap as may displace tendon further proximally). Tourniquet time typically 45-90 minutes for repair.

Forearm Position: SUPINATION MANDATORY - this is the critical protective position maintained throughout surgery. Assistant holds forearm supinated or use arm board with forearm pronated holder that surgeon rotates to supination.

Imaging: Ensure C-arm available if using fluoroscopy to confirm tuberosity position, button deployment, or anchor placement (optional, most surgeons rely on palpation).

Landmarks: Mark with surgical marker:

1. Antecubital fossa crease (incision location)
2. Palpable biceps muscle belly and expected tendon course
3. Radial pulse (marks radial artery course)
4. Lateral epicondyle (reference point)

Step 1: Skin Incision and LABCN Identification

Incision: 3-4cm transverse incision in antecubital fossa skin crease (Langer's lines for optimal cosmesis). Center incision over palpable biceps tendon course or slightly lateral. Deepen through subcutaneous tissue with sharp dissection under direct vision.

LABCN Identification: This is the FIRST and MOST IMPORTANT step. LABCN emerges between lateral edge of biceps/brachialis and medial edge of brachioradialis. Appears as 1-5 small nerve fascicles (variable anatomy) crossing field obliquely from lateral-proximal to medial-distal. Often accompanied by small vessels.

LABCN Protection Strategy:

• Identify all visible branches early
• Gently mobilize with nerve dissector (no traction)
• Tag with vessel loop for visibility
• Protect with Senn retractor or Army-Navy retractor (avoid sharp rake)
• Avoid cautery near nerve
• Check nerve at case end - should be visible and intact

Step 2: Deep Interval Development - BR-PT Plane

Identify Brachioradialis (BR): Lateral muscle, palpable as firm muscle belly, easily identified by its surface anatomy and mobile nature. Originates lateral supracondylar ridge humerus, inserts radial styloid. Innervated by radial nerve (before bifurcation).

Identify Pronator Teres (PT): Medial muscle, two heads (humeral head from medial epicondyle, ulnar head from coronoid), inserts lateral mid-shaft radius. Innervated by median nerve. Forms medial border of working interval.

Develop Interval: The space BETWEEN BR (lateral) and PT (medial) is the working interval. This is a TRUE internervous plane (radial nerve territory vs median nerve territory). Spread bluntly with hemostat or finger dissection. Interval bloodless if proper plane.

Radial Artery Management: Radial artery lies 1-2cm medial to BR, typically adherent to deep surface of BR muscle. Retract BR and radial artery TOGETHER as a unit laterally. Palpate pulse. Gentle handling to avoid spasm or thrombosis.

Step 3: Tendon Identification and Retrieval

Tendon Location: In acute rupture (<4 weeks), tendon typically retracted to level of antecubital crease. In delayed cases (4-12 weeks), may retract to mid-arm. Chronic cases (>12 weeks) may retract to axilla or be scarred in place.

Tendon Retrieval:

• Identify biceps muscle belly proximally (thick, fusiform)
• Follow muscle to musculotendinous junction
• Tendon appears as white, glistening structure with longitudinal fiber pattern
• May be surrounded by hematoma (acute) or scar (chronic)
• Deliver into wound with Kocher clamp or Allis clamp on tendon substance (not edges)
• May require proximal extension of incision or separate 1cm stab incision

Tendon Preparation:

• Debride MINIMALLY - remove only frayed tissue (1-2mm maximum)
• Every millimeter of length is precious
• Remove only non-viable tissue (gray, mushy, no longitudinal fibers)
• Goal: healthy tendon end with intact fiber architecture
• Typical prepared tendon length 2-3cm from musculotendinous junction

Suture Placement:

• Pass locking whipstitch through tendon with #2 FiberWire, FiberTape, or equivalent high-strength suture
• Locking configuration: Start 1cm from end, pass through tendon substance centrally, exit 2cm from end, pass back through creating lock, repeat 3-4 throws creating 2cm of locked suture within tendon
• Ensures suture won't pull through tendon during tensioning
• Leave long suture tails for passage through bone

Step 4: Radial Tuberosity Exposure

Supination - The Critical Maneuver: Ensure forearm in FULL supination. Palpate radial tuberosity - should feel like firm prominence on anteromedial proximal radius 2-3cm distal to radial head. Tuberosity moves ANTERIORLY and MEDIALLY with supination (accessible through anterior approach). In pronation, tuberosity rotates POSTEROLATERALLY (inaccessible, and brings PIN into field).

Tuberosity Preparation:

• Clear soft tissue from tuberosity surface with elevator or freer
• Remove bicipital bursa (normally present, may be thickened)
• Remove any adhesions or scar tissue
• STAY ON BONE - do not dissect laterally or posteriorly off tuberosity
• Expose tuberosity footprint: oval area 15-20mm x 8-12mm
• Gentle decortication with rongeur or curette to create bleeding bone surface (enhances healing)

PIN Protection During Exposure:

• PIN is 3-5cm distal to tuberosity, within supinator muscle
• Supination rotates PIN posteriorly around radial neck - SAFE
• Pronation brings PIN anterolaterally - DANGER
• STAY ON BONE - PIN is muscular, will not be encountered if stay on bony tuberosity
• No lateral or posterior dissection off bone

Step 5: Fixation - Cortical Button Technique (Preferred)

Rationale: Cortical button (EndoButton, TightRope, or equivalent) provides biomechanically strongest fixation. Published biomechanical studies show superior load to failure (300-400N) versus suture anchors (200-300N) or interference screws (150-250N). Button engages posterior cortex distributing load over larger area.

Drilling Technique:

1. Drill Guide Placement: Position drill guide on center of tuberosity footprint (anteromedial oval). Angle drill perpendicular to bone surface (usually 30-40° from vertical, aiming slightly distal).
2. Unicortical Pilot: Drill 3.2mm pilot hole through near cortex only. STOP when feel decreased resistance (entering medullary canal).
3. Posterior Cortex Palpation: Place finger on posterior radial cortex (posterolateral aspect of proximal radius). Feel for pilot hole exiting posteriorly - should not be palpable yet (still unicortical).
4. Bicortical Completion: Change to larger drill bit (4.5mm for most systems). Drill slowly through medullary canal to posterior cortex. FEEL for "give" when enter posterior cortex. STOP immediately after penetrating posterior cortex.
5. Depth Measurement: Use depth gauge through drill hole to measure posterior cortical thickness. Typical 2-3mm. This determines button suture length needed.

Button Deployment:

1. Thread Button: Pass button-attached sutures through prepared tendon (through whipstitch loop or separate holes).
2. Pass Through Bone: Fold button flat, pass through drill hole from anterior to posterior. Button passes through 4.5mm hole easily when folded.
3. Deploy Button: Once button emerges from posterior cortex (feel "pop"), pull sutures anteriorly. Button flips 90° and engages posterior cortex. Confirm deployment by feeling button seated flush on posterior cortex.
4. Dock Tendon: Pull tendon down to tuberosity footprint via button sutures. Tendon end should sit flush on prepared bleeding bone surface.
5. Tension Repair: Position elbow at 30-40° flexion, forearm supinated. Tension button sutures pulling tendon firmly to bone. This tension optimizes healing while allowing full extension post-op.
6. Secure Sutures: Tie button sutures over bone bridge on anterior cortex OR through separate small drill holes. Multiple square knots. Alternative: some systems have self-tensioning mechanisms.

Suture Anchor Technique

Indications: Good alternative when surgeon prefers single-cortex fixation (avoids posterior cortex violation), osteoporotic bone where button may be risky, revision cases where previous button hole present.

Technique:

1. Anchor Placement: Place 2-3 suture anchors (typically 5.0mm or 5.5mm diameter) in radial tuberosity footprint
2. Drill Pilot Holes: Use anchor-specific drill guide, create pilot holes perpendicular to bone surface
3. Insert Anchors: Screw or impact anchors fully seated below bone surface (countersink slightly)
4. Suture Configuration: Pass anchor sutures through tendon in locking mattress or modified Mason-Allen configuration
5. Tension Repair: Position elbow 30-40° flexion, forearm supinated, tie sutures securing tendon to tuberosity
6. Test Fixation: Should be robust - each 5.5mm anchor typically rated 150-200N load to failure

Advantages:

• Single cortex violation (no posterior cortex drilling)
• Theoretically safer for PIN (no posterior hardware)
• Easier technique for less experienced surgeons
• Can use multiple anchors for customized repair

Disadvantages:

• Biomechanically weaker than button (200-300N vs 300-400N)
• Anchor pullout risk in poor bone quality
• Requires adequate bone stock in tuberosity
• Tuberosity fracture risk if anchors too close together
• More expensive (2-3 anchors vs 1 button)

Interference Screw Technique

Technique:

1. Socket Creation: Create unicortical socket in radial tuberosity using cannulated reamer over guidewire
2. Socket Dimensions: Diameter 7-9mm (matches tendon diameter), depth 20-25mm
3. Tendon Docking: Insert prepared tendon into socket with tendon end at socket base
4. Screw Insertion: Advance bioabsorbable interference screw (usually 7mm x 23mm) alongside tendon, compressing it against socket walls
5. Tension: Position elbow 30-40° flexion during screw advancement

Advantages:

• Similar concept to ACL interference fixation (familiar to sports surgeons)
• Single cortex
• No knots
• Good compression of tendon-bone interface

Disadvantages:

• Screw divergence out of socket (10-15% in some series) - major complication
• Larger bone defect than other methods
• Cannot adjust tension after screw inserted
• Fracture risk with oversized socket
• Less commonly used for distal biceps (more data for ACL)

Two-Incision Technique - Detailed Description

Historical Context: Original Boyd-Anderson technique (1961). Fell out of favor due to heterotopic ossification, then modified and reintroduced. Still used by some surgeons, particularly for revision cases or chronic ruptures.

Anterior Incision and Tendon Retrieval: Same as single-incision technique (Steps 1-3 above). 3-4cm transverse antecubital crease incision, identify LABCN, develop BR-PT interval, retrieve tendon, prepare with whipstitch.

Posterior Incision and Approach:

1. Incision: 3-4cm longitudinal incision over posterolateral forearm, 2cm distal to lateral epicondyle, centered over palpable radial neck
2. Interval: Split between extensor digitorum communis (EDC) and extensor carpi ulnaris (ECU) - true internervous plane (radial nerve vs PIN)
3. Supinator Identification: Supinator muscle wraps around radial neck. PIN lies WITHIN supinator muscle substance, entering anteriorly and exiting posteriorly
4. Sub-Supinator Plane: Develop plane BETWEEN supinator (lateral/superior) and interosseous membrane (medial/inferior). This protects PIN which stays in supinator.
5. Tuberosity Palpation: Palpate anteriorly through this plane to identify radial tuberosity on anteromedial radius
6. Drilling: Drill from posterior to anterior through tuberosity. Can palpate drill bit emerging anteriorly.
7. Tendon Passage: Pass tendon from anterior wound through bone tunnel posteriorly (either through drill hole or separate bone tunnel)
8. Posterior Fixation: Secure tendon posteriorly over bone bridge, through button on posterior cortex, or with suture tied over periosteum

Advantages of Two-Incision:

• DIRECT visualization of radial tuberosity from posterior (easier for some surgeons)
• Maximal PIN protection (PIN never near anterior field)
• Easier in obese patients where anterior exposure difficult
• Better for chronic cases or revisions where anterior scarring extensive
• Can address pathology at tuberosity directly (bursitis, osteophytes)

Disadvantages of Two-Incision:

• HETEROTOPIC OSSIFICATION: 5-10% rate versus 1-2% single incision (5-fold higher)
• Two separate bone violations (radius anteriorly and posteriorly)
• Radioulnar synostosis risk (rare, <3%, but catastrophic - complete forearm rotation loss)
• Two scars (cosmetic)
• Longer operative time
• More soft tissue dissection
• Higher complication rate overall

HO Mechanism: Posterior approach requires periosteal stripping of radius posteriorly. Combined with anterior tuberosity violation creates dual ossification stimulus. Hematoma formation between radius and ulna osteogenic. Inflammatory cascade triggers heterotopic bone formation, often bridging radius to ulna (synostosis pattern).

Additional Complications

Median Nerve Injury (<1%):

• Cause: Excessive medial dissection beyond PT muscle, aggressive medial retraction
• Recognition: Post-op numbness thumb/index/middle fingers (radial 3.5 digits), thenar weakness (APB, opponens), Tinel's over nerve
• Prevention: Stay within BR-PT interval, no medial dissection, identify nerve if anatomy unclear
• Management: Most neurapraxia - observe 3-6 months. If neurotmesis, surgical exploration and repair

Radial Shaft Fracture (rare, <1%):

• Cause: Drill hole too large (>5mm), osteoporotic bone, thin cortex, multiple drill attempts
• Recognition: Intraop: Crack heard/felt during drilling. Post-op: Pain, radiographs show fracture line through tuberosity region
• Prevention: Appropriate sized drill (4.5mm for button, not >5mm), gentle technique, assess bone quality, fluoroscopy if unsure
• Management: Most stable and heal with conservative treatment (protected ROM). If displaced: ORIF with plate/screws, protect repair during fracture healing

Wound Complications (2-3%):

• Superficial infection: Antibiotics, local wound care
• Deep infection: Rare, requires washout, hardware removal if chronic, IV antibiotics
• Dehiscence: Re-closure if early, local wound care if late
• Hematoma: Evacuate if tense/expanding, otherwise observe

Chronic Pain (5-8%):

• Multifactorial: Nerve injury (LABCN neuroma most common), stiffness, HO, hardware prominence, regional pain syndrome
• Workup: Examine for specific cause (neuroma Tinel's, HO on imaging, hardware palpable)
• Management: Treat underlying cause, consider neuroma excision if LABCN, HO excision if limiting function, hardware removal if prominent and bothersome after healing

Rehabilitation Timeline - Evidence-Based Protocol

Phase 1: Protection (Weeks 0-2)

• Immobilization: Posterior splint, elbow 90° flexion, forearm NEUTRAL rotation (between supination/pronation for comfort)
• Rationale: Neutral rotation protects repair in both supination and pronation directions, allows tendon-bone healing
• Allowed: Active wrist flexion/extension, finger ROM (prevent stiffness, maintain grip)
• Prohibited: Elbow motion, forearm rotation, lifting, resistance
• Wound care: Suture removal 10-14 days, keep dry until then

Phase 2: Early Motion (Weeks 2-6)

• Bracing: Hinged elbow brace (0-120° or 30-120° depending on surgeon preference and repair strength)
• Motion: ACTIVE elbow flexion encouraged (biceps contracts but minimal load on repair). PASSIVE elbow extension (gravity, therapist assists - avoid active triceps firing). Light forearm rotation (active supination/pronation) in neutral elbow position
• Rationale: Motion prevents stiffness (major problem if immobilized >6 weeks). Active flexion safe because minimal tensile load. Passive extension safe because low load. Active extension prohibited (loads repair)
• Restrictions: NO resisted supination (main load on repair - supinator and biceps both fire). NO lifting >500g. NO active extension (triceps load). NO eccentric biceps loading
• Goals: Achieve 0-130° elbow motion, full forearm rotation, prevent adhesions

Phase 3: Active ROM (Weeks 6-12)

• Bracing: Discontinue brace at 6 weeks if repair strong, motion good, patient compliant
• Motion: Progress to active elbow extension (wean brace, activate triceps), full AROM all planes (flexion, extension, supination, pronation)
• Strengthening: Begin LIGHT resistance at 8 weeks. Isometric biceps contractions. Light resistance bands. Progress gradually
• Restrictions: NO heavy lifting (>2kg). NO eccentric loading. NO sudden forceful activities
• Goals: Full or near-full ROM (0-140° flexion, full rotation), independent ADLs, pain-free motion

Phase 4: Strengthening (Weeks 12-24)

• Progressive Loading: Increase resistance gradually. Concentric strengthening first (biceps curl, supination against resistance). Introduce eccentric loading at 16+ weeks (controlled lowering)
• Return to Activity: Light sports 3 months (golf, swimming). Heavy sports 4-6 months (rock climbing, heavy weightlifting)
• Full Recovery: 4-6 months for complete healing, return to all activities including heavy manual labor
• Restrictions: Avoid lifelong repetitive eccentric biceps loading (mechanism of initial rupture) - patient education on activity modification

Expected Outcomes - Published Data

Strength Recovery:

• Flexion strength: 90-95% of contralateral side at 1 year (excellent recovery)
• Supination strength: 85-90% of contralateral side (slightly more deficit than flexion)
• Untreated rupture loses 40-50% supination strength, 20-30% flexion strength - repair clearly superior

ROM Recovery:

• 90% achieve full or near-full elbow flexion-extension (0-140°+)
• 95% achieve full forearm rotation (supination-pronation)
• 5-10% develop minor flexion contracture (10-20° extension loss) - usually well-tolerated

Return to Work/Sport:

• Sedentary work: 2-4 weeks
• Light manual labor: 6-12 weeks
• Heavy manual labor: 3-6 months
• Competitive sports: 4-6 months

Patient Satisfaction:

• 85-95% satisfied or very satisfied with outcome
• 90-95% would undergo surgery again
• Main dissatisfaction: Residual weakness, nerve numbness (LABCN), stiffness

Functional Outcomes:

• DASH scores: Improvement from 40-50 pre-op to 5-15 post-op (lower = better)
• QuickDASH: Similar improvement
• Return to pre-injury activity level: 80-85% of patients

Complication Impact:

• LABCN injury: Most common complaint, affects satisfaction but not functional scores significantly
• Re-rupture: Devastating, revision surgery outcomes worse (70-80% good vs 90-95% primary)
• HO/synostosis: Significantly impacts outcome, rotation loss affects function
• Stiffness: Minor extension loss (<20°) well-tolerated, >20° affects function

Return to Activity Guidelines

Office Work: 1-2 weeks in splint/brace Driving: 6 weeks (when out of brace, can grip wheel, emergency maneuvers safe) Light Household: 6-8 weeks (dishes, light cooking - no lifting >2kg) Heavy Household: 3-4 months (yard work, moving furniture) Golf: 3 months (controlled swing, no full power initially) Tennis: 4 months (volleys first, serves later) Swimming: 6-8 weeks (gentle strokes, no butterfly initially) Weightlifting: 4-6 months (light weights 3 months, heavy 6 months) Rock Climbing: 6 months (high eccentric load - last to return) Manual Labor: 3-6 months depending on demands