Extensor Tendon Reconstruction

Traumatic Extensor Loss

Mechanisms:

1. Laceration injuries: Clean division allowing primary repair
2. Crush/avulsion: Segmental loss requiring grafting
3. Degloving: Extensive soft tissue damage, compromised healing
4. Closed rupture: Forceful flexion against resistance (Zone V-VII)

Failed Primary Repair:

• Gap formation: Inadequate repair strength, excessive tension
• Adhesion formation: Insufficient early mobilization, excessive scarring
• Re-rupture: Premature rehabilitation, weak repair construct
• Tendon necrosis: Vascular compromise, infection

Chronic Presentation:

• Retraction: Proximal tendon retracts to muscle-tendon junction
• Muscle contracture: Myostatic contracture after 3-6 months
• Distal stump fibrosis: Scar tissue replaces distal tendon
• Joint stiffness: Secondary contractures from prolonged immobility

This pathophysiology necessitates reconstruction rather than delayed primary repair.

Rheumatoid Extensor Ruptures

Vaughan-Jackson Syndrome:

• Sequential extensor tendon ruptures from distal DRUJ synovitis
• Mechanism: Chronic synovitis erodes tendons over bony prominences
• Caput ulnae syndrome: Dorsal DRUJ prominence with ECU subluxation

Rupture Sequence (Ulnar to Radial):

1. EDM (small finger) - first to rupture
2. EDC ring finger - second
3. EDC middle finger - third
4. EDC index finger - fourth
5. EPL at Lister's tubercle (Mannerfelt lesion)

Pathology:

• Attrition rupture: Tendon fraying over distal ulna
• Inflammatory rupture: Synovitis invades tendon substance
• Ischemic rupture: Vascular compromise from inflammation

Clinical Recognition:

• Progressive finger drop: Sequential loss of MCP extension
• Palpable tendon absence: No cord with attempted extension
• Differentiate from synovitis: Weak extension (synovitis) vs absent extension (rupture)

Reconstruction must address both ruptured tendons and underlying DRUJ pathology.

Atraumatic Extensor Ruptures

EPL Rupture Post-Colles Fracture:

• Incidence: 0.5-3% of distal radius fractures
• Timing: Typically 4-12 weeks post-fracture (delayed presentation)
• Mechanism: Ischemic necrosis within tight third dorsal compartment at Lister's tubercle
• Risk factors: Greater displacement, longer immobilization, smoking

Other Atraumatic Causes:

• Distal radius malunion: Chronic EPL attrition over dorsal prominence
• Steroid injections: Tendon degeneration from local corticosteroid
• Fluoroquinolone use: Quinolone-associated tendinopathy
• Inflammatory arthropathies: Psoriatic, reactive arthritis
• Chronic overuse: Repetitive wrist extension (rare)

Clinical Pearl: EPL rupture presents as sudden inability to extend thumb IP joint without preceding trauma - pathognomonic for atraumatic rupture.

These patients have excellent soft tissue and typically achieve best reconstruction outcomes.

History

Chief Complaint:

• Inability to extend specific digit(s) or thumb
• Extensor lag: Incomplete extension despite effort
• Triggering/catching: Suggests adhesions rather than rupture
• Progressive weakness: Rheumatoid pattern

Timeline:

• Acute onset: Laceration, closed rupture (recent trauma)
• Subacute (weeks): Post-Colles EPL rupture (4-12 weeks)
• Progressive (months): Rheumatoid sequential ruptures
• Chronic (greater than 6 months): Failed repairs, late presentation

Functional Impact:

• Thumb EPL loss: Difficulty with precision pinch, turning keys, opening jars
• Finger EDC loss: Inability to release objects, weak grip, compensatory IP hyperextension
• Multiple digit involvement: Severe hand dysfunction, inability to work

Previous Interventions:

• Prior surgery: Number of procedures, types, outcomes
• Splinting history: Response to dynamic extension splints
• Therapy compliance: Intensive therapy required for success

Physical Examination

Inspection:

• Resting posture: Affected digit(s) in relative flexion
• Surgical scars: Indicate prior attempts, scar quality
• Skin quality: Thin, scarred skin suggests difficult reconstruction
• Muscle wasting: Thenar atrophy (EPL loss), forearm atrophy (long-standing)

Palpation:

• Tendon continuity: Palpate extensor mass during attempted extension
  • Present: Thickened cord suggests intact but adherent tendon
  • Absent: Gap or no palpable structure confirms rupture
• Distal DRUJ: Dorsal prominence, synovitis (rheumatoid)
• Muscle contraction: Palpable forearm muscle contraction despite no distal motion confirms rupture

Range of Motion:

Critical Assessment - PASSIVE ROM FIRST:

1. PIPJ passive flexion-extension: Must be full (0-100 degrees)
2. DIPJ passive flexion-extension: Must be full (0-80 degrees)
3. MCP passive flexion-extension: Must be full (0-90 degrees)
4. Thumb IP/MCP passive motion: Must be full
5. Wrist passive motion: Should be functional (30-60 degrees flexion-extension)

If passive ROM limited - STOP. Address joint stiffness before any tendon work.

Active ROM:

• Isolated tendon testing:
  • EPL: Extend thumb IP with hand flat on table (positive test = cannot lift thumb)
  • EIP: Extend index finger with others flexed and held
  • EDC: Extend each finger independently
• Extensor lag measurement: Degrees from full passive extension to active extension
• Compensatory patterns: IP hyperextension, intrinsic recruitment

Special Tests:

EPL Rupture Test:

• Hand flat on table, palm down
• Patient attempts to lift thumb off table
• Positive: Thumb remains flat (EPL ruptured)
• Negative: Thumb lifts easily (EPL intact)

Juncturae Tendinum Test:

• Immobilize middle, ring fingers in flexion
• Attempt index or small finger extension independently
• Limited extension: Dependent on juncturae (true independent extensor lost)

Intrinsic Tightness Test:

• Passively extend MCP joint, attempt PIP flexion
• Limited PIP flexion with MCP extended: Intrinsic tightness present
• Differentiate from extensor tightness (limits PIP flexion with MCP flexed)

Differential Diagnosis

Imaging

Radiographs (AP, Lateral, Oblique):

Indications: All chronic extensor deficiency cases

Findings to assess:

• Bony prominences: Distal ulna (Vaughan-Jackson), Lister's tubercle (EPL rupture site)
• Malunion: Distal radius dorsal angulation causing tendon attrition
• Hardware: Prominent screws/plates causing mechanical attrition
• Arthritis: DRUJ, wrist, finger joints affecting reconstruction candidacy
• Fracture healing: Confirm union before reconstruction (Colles cases)

Ultrasound:

Indications:

• Confirm rupture vs adhesions
• Locate retracted tendon ends
• Assess tendon quality

Technique: High-frequency linear probe (greater than 10 MHz), dynamic assessment

Findings:

• Complete rupture: Tendon discontinuity, retracted stumps, gap
• Partial rupture: Thinned tendon, partial continuity
• Adhesions: Intact tendon with limited excursion
• Synovitis: Hypoechoic fluid around tendons (rheumatoid)

Advantages: Real-time, dynamic assessment, low cost, no radiation

MRI (T1, T2, STIR sequences):

Indications:

• Uncertain diagnosis
• Pre-operative planning for complex cases
• Assessment of muscle quality (atrophy, fatty infiltration)
• Evaluation of joint pathology

Findings:

• Tendon rupture: Signal discontinuity, tendon retraction, fluid in sheath
• Tendon quality: Thickened (chronic inflammation), thinned (attrition)
• Muscle atrophy: Reduced muscle bulk, T1 hyperintensity (fatty infiltration)
• Synovitis: T2/STIR hyperintensity around DRUJ, wrist
• Scar tissue: T1/T2 hypointensity in tendon bed

Limitations: Expensive, time-consuming, claustrophobia

Electrodiagnostic Studies (EMG/NCS):

Indications: Suspected nerve injury (PIN palsy) masquerading as tendon rupture

Findings:

• PIN palsy: Denervation in all finger/thumb extensors, wrist extensors (ECRB) spared
• Tendon rupture: Normal motor units, voluntary recruitment present

Useful to differentiate neurologic from tendon pathology.

Laboratory Studies

Rheumatoid Cases:

• Inflammatory markers: ESR, CRP (assess disease activity)
• Rheumatoid factor: Confirm RA diagnosis
• Anti-CCP antibodies: More specific for RA

Infection workup (if concerned):

• CBC: Leukocytosis suggests infection
• Blood cultures: If systemic signs
• Wound cultures: If draining sinus

Preoperative Assessment

Passive ROM Documentation:

• Critical: Measure and document passive ROM all joints
• Photography: Consider photos documenting passive motion
• Consent discussion: If passive ROM limited, discuss joint surgery first

Donor Availability:

• Palmaris longus test: Oppose thumb to small finger, flex wrist - look for central cord
  • Present: 85% of population
  • Absent: Consider plantaris or ECRL
• EIP presence: Should be present in all patients (very rare congenital absence)

Soft Tissue Assessment:

• Skin quality: Thin/scarred skin may require flap coverage
• Previous incisions: Plan incisions to avoid skin necrosis
• Infection history: Delay reconstruction if recent infection

Patient Factors:

• Occupation: Return to work expectations, timeline
• Hand dominance: Dominant hand may justify more aggressive reconstruction
• Therapy access: Access to certified hand therapist essential
• Compliance: Realistic assessment of ability to follow complex protocol

EIP to EPL Transfer Technique

Gold Standard for EPL Rupture

Indications:

• Chronic EPL rupture (post-Colles, rheumatoid, idiopathic)
• Failed EPL primary repair
• EPL loss from trauma

Advantages:

• EIP expendable (EDC provides adequate index extension)
• Similar excursion to EPL (5-7cm)
• Direct line of pull after rerouting
• Excellent success rate (90-95%)

Patient Positioning:

• Supine, arm on hand table
• Tourniquet on upper arm (250 mmHg)
• Hand pronated

Surgical Approach - Three Incisions:

Incision 1 - Dorsal Index MCP (2cm longitudinal):

• Identify EIP tendon (ulnar to EDC at MCP level)
• Typically both tendons visible to index - EIP is ulnar
• Tag EIP with marking suture
• Divide EIP as distally as possible (at extensor hood)
• Retrieve EIP proximally with traction

Incision 2 - Dorsal Wrist/Distal Forearm (4-5cm):

• Center over Lister's tubercle
• Extend 4cm proximally over EPL muscle belly
• Identify third dorsal compartment (EPL)
• Open compartment - find EPL distal stump (may be attenuated)
• Trace EPL muscle belly proximally - excise degenerated tendon
• Create subcutaneous tunnel from wrist incision to thumb (radial side)

Incision 3 - Thumb Dorsal IP Joint (1.5cm):

• Longitudinal over IP joint dorsum
• Identify EPL insertion on distal phalanx base
• Prepare EPL stump by freshening if adequate tissue
• If no distal stump: create bone tunnel in distal phalanx

Transfer Procedure:

1. Retrieve EIP from index incision into wrist incision
2. Pass EIP subcutaneously around radial wrist (mimic EPL course)
3. Thread EIP through subcutaneous tunnel to thumb incision
4. Weave EIP to EPL stump using Pulvertaft weave:
   • Create 4-6mm longitudinal slit in EPL stump
   • Pass EIP through slit
   • Create second slit 5mm distal, pass EIP through again
   • Repeat for 3-4 total weaves
   • Suture each weave with 4-0 Ethibond/FiberWire
5. Set tension: Wrist neutral, thumb MCP/IP joints extended (can passively flex to neutral)
6. Intraoperative test: Passive wrist flexion extends thumb; wrist extension allows thumb flexion
7. Trim excess EIP tendon

If no EPL distal stump available:

• Drill 2mm bone tunnel from dorsal to volar distal phalanx base
• Pass EIP through tunnel
• Suture to periosteum or button over volar pulp

Closure:

• Skin only (5-0 nylon or subcuticular)
• Avoid deep sutures (restrict glide)

Immobilization:

• Thumb spica splint
• Wrist 30 degrees extension
• Thumb CMC, MCP, IP extended
• Duration: 4 weeks

This technique provides excellent thumb extension restoration with minimal donor morbidity.

Free Tendon Graft Technique

Indications:

• Segmental tendon loss (trauma, infection)
• Insufficient local tissue for transfer
• Multiple tendon ruptures requiring grafts

Graft Donor Selection:

Palmaris Longus (First Choice):

• Availability: Present in 85%
• Length: 12-15cm
• Diameter: 3-4mm (suitable for extensors)
• Harvest morbidity: Minimal (no functional deficit)

Plantaris (Second Choice):

• Availability: Present in greater than 90%
• Length: 25-30cm (excellent for multiple grafts)
• Diameter: 2-3mm
• Harvest morbidity: Requires foot incision, minimal functional deficit

Toe Extensors - EHL/EDL (Third Choice):

• Availability: Always present
• Length: 8-12cm each
• Harvest morbidity: Moderate (requires foot surgery, possible toe extension weakness)

Palmaris Longus Harvest Technique:

1. Confirm presence: Oppose thumb-small finger, flex wrist → palpate central cord
2. Incision: 2cm transverse at wrist flexion crease (just ulnar to midline)
3. Identify PL: Between FCR (radial) and FCU (ulnar)
4. Divide distally: At wrist crease level
5. Harvest: Use tendon stripper OR make second 1cm incision mid-forearm, divide proximally, extract
6. Length: Typically 12-15cm obtained
7. Store: Keep moist in saline-soaked gauze, tag both ends
8. Closure: Simple skin closure

Graft Weaving Technique (Pulvertaft Weave):

At Distal Attachment (to recipient tendon stump):

1. Prepare distal extensor stump (freshen if degenerative)
2. Create 4-6mm longitudinal slit in stump
3. Pass graft through slit from dorsal to volar
4. Create second slit 5mm distal to first
5. Pass graft through second slit (volar to dorsal)
6. Repeat for total of 3-4 weaves
7. Suture each weave with 4-0 Ethibond (non-absorbable)
8. Final weave ends dorsally

At Proximal Attachment (to motor tendon):

• Same Pulvertaft weave technique
• Pass graft through motor tendon (EDC or ECRB)
• 3-4 weaves with sutures
• Set tension BEFORE final sutures:
  • Wrist neutral position
  • MCP joints 45 degrees flexion (for fingers)
  • Thumb extended (for EPL)
  • Test passive wrist motion → reciprocal finger motion
• Trim excess graft, taper end

Critical Technical Points:

• Adequate weave number: 3 weaves minimum (80% strength), 4 weaves ideal (90% strength)
• Avoid excessive bulk: Smooth tapered juncture (reduces catching/adhesions)
• Tension setting: Most critical step - determines final function
• Secure suturing: Non-absorbable sutures (Ethibond, FiberWire) prevent unraveling

Immobilization:

• Dorsal blocking splint
• Wrist 30 degrees extension
• MCP 0 degrees extension
• IP joints free
• Duration: 4 weeks

Outcomes: 75-85% good-excellent results (lower than transfers due to avascularity of graft requiring healing).

Two-Stage Tendon Reconstruction

Indications:

• Severe scarring/adhesions from multiple prior surgeries
• Failed single-stage graft (adhesions)
• Post-burn reconstruction with contracted skin
• Infected wound bed (after infection cleared)

Principle: Create gliding pseudosheath around silicone rod (stage 1), then replace rod with tendon graft through pseudosheath (stage 2).

Stage 1 - Silicone Rod Insertion:

Timing: Minimum 3 months after injury/prior surgery (scar maturation)

Technique:

1. Expose distal insertion site: Identify or prepare attachment point
2. Expose proximal motor unit: Identify EDC, ECRB, or other motor tendon
3. Pass silicone Hunter rod:
   • Size 3 or 4mm diameter (match extensor size)
   • Thread rod from distal to proximal through scarred bed
   • Use curved hemostat, infant feeding tube, or similar instrument to guide
   • Avoid creating false passages
4. Anchor rod distally:
   • Suture to distal stump or bone (prevents migration)
   • Use non-absorbable 3-0 suture
5. Anchor rod proximally:
   • Suture to muscle-tendon junction of motor
   • Leave adequate length for stage 2 retrieval
6. Closure: Routine skin closure
7. Immobilization: Protective splint for 2 weeks

Post-Stage 1 Management:

• Protective splinting for 2 weeks
• Begin gentle passive ROM weeks 2-12 (forms pseudosheath)
• Wait 3 months minimum before stage 2 (allow pseudosheath formation)

Stage 2 - Rod Removal and Graft Insertion:

Timing: 3-6 months after stage 1 (pseudosheath fully formed)

Pre-operative Assessment:

• Confirm passive ROM adequate (critical)
• Palpate rod course (should glide smoothly)
• Harvest graft donor (palmaris, plantaris)

Technique:

1. Expose distal rod end: Through small incision at original distal site
2. Expose proximal rod end: Through incision over motor unit
3. Attach graft to distal rod end:
   • Suture graft to rod tip with heavy suture (0 or 2-0)
   • Use locking whipstitch for security
4. Pull rod proximally:
   • Grasp rod at proximal incision
   • Gently pull rod through pseudosheath (drawing graft distally)
   • Rod emerges proximally with graft following
5. Weave graft distally:
   • Pulvertaft weave to distal insertion (3-4 weaves)
   • Or anchor to bone if no stump
6. Weave graft proximally:
   • Pulvertaft weave to motor unit
   • Set tension carefully: Wrist neutral, MCP 45 degrees flexion
   • Test passive motion before final sutures
7. Closure: Routine

Immobilization: Same as single-stage graft (4 weeks splinting)

Advantages of Two-Stage:

• Creates optimal gliding surface in scarred bed
• Allows assessment of pseudosheath before committing graft
• Better outcomes than single-stage in scarred cases

Disadvantages:

• Two operations, longer recovery
• Rod migration risk (prevent with secure fixation)
• Pseudosheath formation not guaranteed
• Lower success than primary reconstruction (70-80% vs 85-95%)

This technique is reserved for difficult cases where single-stage likely to fail.

Side-to-Side Extensor Transfers

Indications:

• Single EDC rupture with intact adjacent tendons
• Rheumatoid sequential ruptures (early intervention)
• Segmental EDC loss where graft not feasible

Principle: Connect ruptured extensor to adjacent intact extensor via juncturae tendinum or direct suture - allows coupled extension.

Advantages:

• Simple technique, minimal dissection
• No donor tendon sacrifice
• Preserves some independent extension via juncturae
• Good success rate (85-90%)

Disadvantages:

• Loss of independent finger extension
• Requires intact adjacent tendon
• May create extension lag if tension inadequate

Technique for Single EDC Rupture:

1. Incision: Transverse or longitudinal over dorsal MCP joints

2. Identify ruptured tendon: Palpate during extension attempt - gap/absence

3. Identify intact adjacent tendons: Typically one or both neighbors intact

4. Prepare ruptured stump:

   • Freshen proximal and distal stumps
   • If distal stump absent: expose extensor hood

5. Side-to-side transfer options:

   Option A - Direct suture to adjacent tendon:

   • Place affected finger in extension alongside intact neighbor
   • Suture ruptured proximal stump to side of adjacent intact EDC
   • Use 3-0 or 4-0 Ethibond, multiple horizontal mattress sutures
   • Set tension: Affected finger extends to same level as donor

   Option B - Juncturae reinforcement:

   • Identify juncturae tendinum between affected and adjacent tendon
   • Incise juncturae partially, create longer bridge
   • Suture ruptured stump to juncturae
   • Suture juncturae to distal stump

   Option C - Weave technique (most secure):

   • Create slit in adjacent intact EDC
   • Pass ruptured proximal stump through slit (Pulvertaft-style)
   • Weave 2-3 times
   • Suture each weave

6. Tension setting:

   • Wrist neutral
   • Affected MCP joint extended to same level as donor digit
   • Test passive motion intraoperatively

7. Closure: Routine

Immobilization:

• Dorsal blocking splint
• Wrist 30 degrees extension, MCPs 0 degrees
• Affected and donor digits taped together (buddy tape)
• Duration: 3-4 weeks

Rheumatoid Multiple Ruptures - Combined Technique:

For 2-3 ruptures (typical Vaughan-Jackson):

• EDM to EDC ring (side-to-side)
• EIP to EDC middle (transfer)
• Perform DRUJ synovectomy + Darrach/Sauve-Kapandji (prevent recurrence)

This approach restores extension while addressing underlying pathology.