High Yield Overview

FLEXOR TENDON REPAIR - ZONE 2

Primary surgical repair of acute flexor tendon lacerations in Zone 2 ('no man's land') using multi-strand core suture techniques with pulley preservation and early active motion rehabilitation protocols

Critical Danger Structures - 5 Zones

Radial Digital Neurovascular Bundle

Location: Runs 2-3mm RADIAL to flexor sheath along entire digit, deep to skin and superficial to sheath, courses with radial digital artery

Protection: Raise full-thickness skin flaps carefully, identify NV bundle BEFORE opening sheath, retract gently with vessel loop, avoid cautery within 5mm of nerve

Ulnar Digital Neurovascular Bundle

Location: Runs 2-3mm ULNAR to flexor sheath along entire digit, mirror image of radial bundle, courses with ulnar digital artery

Protection: Same as radial bundle - early identification crucial, gentle retraction with moist vessel loop, preserve at least one digital artery per finger

A2 Annular Pulley

Location: Over proximal half of proximal phalanx - 15-17mm length in index/long fingers, 12-15mm in ring/small fingers, provides 50% of total pulley force

Protection: Preserve minimum 50% of pulley (preferably central portion), can vent distal 25% if repair bulky, mark pulley edges before opening sheath to aid identification

A4 Annular Pulley

Location: Over middle third of middle phalanx - 7-9mm length, provides 25% of pulley force, works synergistically with A2 to prevent bowstringing

Protection: Preserve minimum 50% (preferably central), can vent proximal 25% if needed, need combined A2 + A4 length greater than 1.2cm for biomechanical stability

Vincula Blood Supply to Tendons

Location: Vinculum longus (to FDP and FDS) and vinculum brevis (to FDP insertion) - delicate vascular mesenteries entering tendons dorsally within flexor sheath

Protection: Minimize sheath opening (preserve vincula), avoid excessive tendon handling, consider partial sheath closure to maintain synovial nutrition, vincula damage increases ischemia and adhesions

Mnemonic

P.U.L.L.E.YPULLEY - Critical Pulleys to Preserve

Mnemonic

S.T.R.A.N.DSTRAND - Multi-Strand Repair Essentials

Zone Classification System

Zone 1: FDS insertion (middle of middle phalanx) to FDP insertion (base of distal phalanx)

Contains FDP tendon only (FDS already inserted)
Relatively simple repair - single tendon
Can consider FDP advancement if retracted

Zone 2: A1 pulley to FDS insertion - "NO MAN'S LAND"

WORST PROGNOSIS historically (before modern techniques)
Contains BOTH FDP and FDS within tight flexor sheath
Five annular pulleys (A1-A5) and three cruciate pulleys (C1-C3)
Critical anatomy: A2 and A4 pulleys MUST be preserved
High risk of adhesions due to limited space

Zone 3: Distal edge of carpal tunnel to A1 pulley (palm)

Lumbrical muscles originate from FDP tendons here
More space than Zone 2 - better prognosis
Watch for digital nerve branches

Zone 4: Within carpal tunnel

Contains 8 FDP tendons, 4 FDS tendons, median nerve
Repair complicated by median nerve proximity
Multiple tendon injuries common

Zone 5: Proximal to carpal tunnel (distal forearm)

Musculotendinous junction proximity
Median and ulnar nerve injuries common
Better prognosis - ample space for repair

Pulley Anatomy and Biomechanics

Annular Pulleys (5 total - A1 through A5):

A1: Over MCP joint (8-10mm length)
A2: Over proximal phalanx (15-17mm in index/long, 12-15mm ring/small) - CRITICAL
A3: Over PIP joint (3-5mm length)
A4: Over middle phalanx (7-9mm length) - CRITICAL
A5: Over DIP joint (variable length)

Cruciate Pulleys (3 total - C1, C2, C3):

Located between annular pulleys
C1: Between A2 and A3
C2: Between A3 and A4
C3: Between A4 and A5
ALL can be sacrificed to improve exposure

Biomechanical Principles:

A2 pulley provides 50% of total pulley force
A4 pulley provides 25% of total pulley force
Combined A2 + A4 provide 75% of force
Need minimum 1.2cm total pulley length to prevent bowstringing
Must preserve minimum 50% of both A2 AND A4
Loss of >50% of A2 or A4 = bowstringing = loss of mechanical advantage = weak grip

FDS and FDP Tendon Anatomy in Zone 2

Flexor Digitorum Superficialis (FDS):

Inserts on middle third of middle phalanx (volar surface)
Splits into TWO SLIPS (radial and ulnar) proximal to Zone 2
Slips decussate around FDP at "Chiasm of Camper"
Each slip runs along side of FDP then reunites and inserts
Provides PIPJ flexion and grip strength
Can function without FDS (especially index/long fingers)

Flexor Digitorum Profundus (FDP):

Inserts on base of distal phalanx (volar surface)
Provides DIPJ flexion (ONLY flexor of DIPJ)
MANDATORY to repair (finger non-functional without FDP)
All four FDP tendons share common muscle belly in forearm
If one FDP shortened = quadriga effect (limits all fingers)

Vincular Blood Supply:

Vinculum longus superficialis - to FDS
Vinculum longus profundus - to FDP
Vinculum brevis superficialis - to FDS insertion
Vinculum brevis profundus - to FDP insertion
Enter tendons dorsally through sheath
Preserve by minimizing sheath opening and careful handling

Step-by-Step Operative Technique

Step 1: Exposure and Wound Extension

Extend the traumatic laceration using BRUNER ZIGZAG incisions. Angle each segment 60 degrees to flexion creases (NEVER perpendicular - causes hypertrophic scar and contracture). Place apex of each zigzag at the midaxial line. Each zigzag segment should be 5-8mm in length. Raise full-thickness skin flaps to expose the flexor sheath. If needed for proximal retrieval, extend into palm with further zigzags or careful longitudinal incision between neurovascular bundles.

Exam Pearl

Technical Tip: EXAM KEY - Bruner incision angles matter. 60-degree angles allow crossing creases obliquely without tension. 90-degree crossing causes web space contracture. Mark incision with skin marker before inflating tourniquet (skin landmarks clearer). Raise full-thickness flaps (skin and subcutaneous fat together) - avoids undermining and necrosis. Identify digital nerves BEFORE opening sheath - they run 2-3mm from sheath edge.

Dangers at this step

Crossing creases perpendicularly (90 degrees) - causes web space contracture
Thin or irregular skin flaps - risk of necrosis
Iatrogenic injury to digital neurovascular bundles - identify early
Inadequate proximal extension - cannot retrieve retracted tendon

Step 2: Flexor Sheath Opening and Pulley Preservation

Mark the edges of the flexor sheath with marking pen before opening (aids closure later). Open sheath between pulleys to expose tendons. PRESERVE A2 pulley (over proximal phalanx) and A4 pulley (over middle phalanx) - these are CRITICAL. Excise or widely vent C1, C2, and C3 cruciate pulleys to improve exposure. If repair will be bulky, can vent distal 25% of A2 or proximal 25% of A4 but MUST preserve central portions. Need minimum 50% of both A2 and A4 intact.

Exam Pearl

Technical Tip: EXAM KEY - A2 provides 50% of pulley force, A4 provides 25%. Together they prevent bowstringing. Biomechanics requires greater than 1.2cm total pulley length. All C pulleys can be sacrificed - they provide minimal force and often cause catching. If greater than 50% of A2 or A4 destroyed by injury, plan pulley reconstruction (usually at delayed stage). Use micro-scissors for precise pulley venting.

Dangers at this step

Complete A2 or A4 pulley release - causes bowstringing and loss of mechanical advantage
Cutting wrong structure (FDS mistaken for sheath)
Injuring intact tendons during sheath opening
Opening sheath too narrowly - inadequate exposure, difficult repair

Step 3: Proximal Tendon Retrieval

Retrieve the proximal FDP tendon end which commonly retracts into palm or carpal tunnel due to lumbrical pull and FDP muscle contraction. Techniques: (1) Gentle milking from proximal palm toward finger, (2) Pass pediatric feeding tube (6Fr) or infant urethral catheter proximally through sheath, make small transverse palm incision, retrieve catheter, attach suture to tendon, pull back into finger. FDS usually retracts less (stays in finger). Identify BOTH tendons. Mark tendons with different colored sutures to prevent rotation.

Exam Pearl

Technical Tip: EXAM KEY - FDP retracts MORE than FDS because FDP muscle is stronger and lumbricals pull on it. Pediatric feeding tube technique: thread proximally, transverse palm incision in distal palmar crease (1cm), retrieve tube, use Keith needle to pass suture through FDP tendon end, tie suture to tube, pull back into finger. AVOID ROTATION - mark volar surface of tendon or use asymmetric suture so you know orientation.

Dangers at this step

Unable to retrieve proximal end (missed in palm, needs wider search)
Excessive proximal dissection (creates adhesions in palm)
Tendon rotation during retrieval (causes maltracking and poor excursion)
Injury to palmar structures during retrieval (digital nerve branches, lumbricals)

Step 4: Tendon Assessment and Preparation

Assess both FDS and FDP injuries. Determine extent of laceration (complete vs partial, percentage of cross-section). FDP repair is MANDATORY (only DIPJ flexor). FDS decision based on: sheath capacity, finger digit (index/long tolerate loss better), extent of injury. Options: repair both slips, repair one/excise one (most common), excise both. Freshen tendon ends with sharp blade perpendicular to long axis. MINIMAL debridement - preserve length to prevent quadriga or excessive tension.

Exam Pearl

Technical Tip: EXAM KEY - FDS management controversial. MOST COMMON: repair one slip (radial/dorsal), excise one slip (ulnar/volar). This balances bulk reduction with some FDS function. If excising FDS, remove the excised slip completely to A1 pulley (don't leave stumps - they cause adhesions). Minimal debridement critical - trim only crushed tissue. Each 1mm of lost length creates tension and shortening. Check tendon orientation (volar vs dorsal surface).

Dangers at this step

Excessive debridement (creates gap too large to close primarily)
Over-bulking repair (both FDS slips + FDP = triggering and adhesions)
Missing partial lacerations (incomplete cuts can complete later)
Wrong assessment of FDS vs FDP (identify by tracking to insertion)

Step 5: Core Suture Placement - FDP Primary Repair

Place multi-strand core suture using 3-0 or 4-0 braided non-absorbable (Ethibond, Ticron, FiberWire). Minimum 4-STRAND technique, preferably 6-STRAND (Adelaide or Savage). Use LOCKING configuration for maximum strength. Purchase tendon 7-12mm from cut edge with each pass. Ensure NO GAP at repair site (less than 1mm acceptable). Equal tension on all strands. Bury knots to prevent surface irregularity. Repair strength: 4-strand = 40-50N, 6-strand = 60-80N (need greater than 50N for early active motion).

Exam Pearl

Technical Tip: EXAM KEY - Adelaide 6-strand technique most popular. Uses three sutures (each creates 2 strands). Each suture: enter volar, exit dorsal 7-10mm from cut, cross repair site buried, lock on opposite end, exit volar. Locking loops 20-30% stronger than grasping loops. Test repair with gentle traction (should hold without gap). If gap forms with gentle tension, repair inadequate (add strands or redo). Core suture provides 50-90% of total repair strength (epitendinous adds remainder).

Dangers at this step

Insufficient strands (less than 4) - rupture risk 10-15%
Gap at repair site greater than 2mm (heals with lengthening, poor function)
Sutures too close to cut edge (less than 5mm - cheese-wiring)
Unequal tension on strands (some slack, some tight - uneven load distribution)
Knots on surface (trigger through pulleys)

Step 6: Epitendinous Suture Application

Apply RUNNING PERIPHERAL (epitendinous) suture using 5-0 or 6-0 monofilament (Prolene, Nylon). Start 180 degrees from core suture knot. Use continuous running technique around entire circumference of repair. Multiple passes - simple running, cross-stitch, or Halstead technique. Keep bites shallow (0.5-1mm deep) to avoid devascularization. 2mm apart. Pull snug but not overly tight. This adds 10-50% strength AND creates smooth gliding surface. Bury core knots. Prevents gap formation.

Exam Pearl

Technical Tip: EXAM KEY - Epitendinous is NOT optional (often underemphasized but CRITICAL). Adds 10-50% to total strength (average 25%). More importantly, creates smooth surface for gliding through pulleys (prevents triggering and adhesions). Cross-stitch (Lin) technique strongest - running locked figure-of-8 pattern. Start 180 degrees from core knot, run circumferentially, bites perpendicular to long axis, 2mm apart, 0.5-1mm deep. Finish near start. AVOID bunching - keep tension even.

Dangers at this step

Omitting epitendinous (weak repair + rough surface = triggering)
Bunching of tendon (creates bulk, catches in pulleys)
Bites too deep (greater than 2mm - devascularizes tendon)
Suture too tight (strangulates repair, causes ischemia)
Using absorbable suture (loses strength before tendon heals)

Step 7: FDS Tendon Management

If repairing FDS: use same multi-strand technique but fewer strands acceptable (2-4 strand sufficient). Each FDS slip can be repaired separately if both being repaired. If excising one or both slips: cut distal to chiasm of Camper, remove excised slip completely from sheath to A1 pulley level (don't leave stumps - they create adhesion nidus). If both slips excised, remove all FDS tissue from Zone 2.

Exam Pearl

Technical Tip: EXAM KEY - FDS management debate. Arguments FOR repair: preserves PIPJ independent flexion, stronger power grip, may provide mass effect preventing FDP adhesions to bone. Arguments AGAINST: increases bulk (higher adhesion rate), may trigger in tight sheath, fingers work well with FDP alone. COMMON PRACTICE: repair one slip (usually radial/dorsal), excise one slip (ulnar/volar). Provides bulk reduction while maintaining some FDS function.

Dangers at this step

Over-bulking (two tendon repairs in tight Zone 2 sheath)
Leaving FDS stumps (stumps create adhesions and serve no function)
Asymmetric FDS repair (imbalanced PIPJ flexion, ulnar or radial deviation)
Injury to FDP during FDS manipulation

Step 8: Pulley System Assessment

Test tendon gliding through pulley system with passive finger flexion and extension under direct vision. Tendon should glide smoothly without catching or triggering. If catching occurs: (1) Assess suture bulk - may need to adjust epitendinous or reduce knots, (2) Vent additional C pulleys if not already done, (3) Consider venting distal 25% of A2 or proximal 25% of A4 (preserve central portions). Check for bowstringing with finger flexed - should be none visible. If bowstringing present, insufficient pulley preserved.

Exam Pearl

Technical Tip: EXAM KEY - Intraoperative gliding assessment CRITICAL. Passively flex/extend finger while watching tendon under loupe magnification. Should see smooth gliding without catching or jerking. ANY catching = will trigger post-operatively = adhesions guaranteed. If catches, MUST address before closing. Bowstringing test: flex finger, look for tendon lifting away from bone (should stay close to bone surface). Bowstringing = mechanical disadvantage = weak grip even if tendon heals.

Dangers at this step

Missed catching (leads to adhesions and rupture risk)
Excessive pulley release trying to fix catching (causes bowstringing)
Asymmetric pulley loss (causes angular deformity with flexion)
Accepting marginal gliding (must be smooth, not "good enough")

Step 9: Flexor Sheath Closure

Close flexor sheath LOOSELY with 5-0 or 6-0 absorbable suture (Vicryl, Monocryl). Leave VENTS - do not close entire sheath circumferentially. Close enough to maintain pulley geometry but allow synovial fluid circulation. Many surgeons leave sheath widely open (only close at pulley sites). If vented pulleys, approximate edges loosely. CONTROVERSIAL - studies show similar results with open vs closed sheath if pulleys preserved. Key principle: LOOSE closure, NO TENSION on repair.

Exam Pearl

Technical Tip: EXAM KEY - Sheath closure debate ongoing. TRADITIONAL: close to maintain anatomy and pulley function. MODERN: many leave open or partially close to reduce adhesions and constriction. COMPROMISE: close at pulley sites (A2, A4) with multiple vents between pulleys, leave C pulley areas completely open. Some surgeons close sheath if substantial sheath lost (maintains synovial space), leave open if most sheath intact. NO WRONG ANSWER if pulleys preserved and closure loose.

Dangers at this step

Tight circumferential closure (strangulates repair, causes ischemia)
Constriction at repair site (triggering guaranteed)
Inadequate venting (blocks synovial fluid flow)
Sutures through repair (incorporates repair into sheath - adhesions)

Step 10: Skin Closure and Dressing

Close skin with 4-0 or 5-0 non-absorbable interrupted sutures (Nylon, Prolene). Use vertical mattress or simple interrupted technique. Ensure good apposition without tension (skin flaps are delicate). Bruner incision: close apex of each zigzag first to ensure alignment. Apply non-adherent dressing (Xeroform, Adaptic) directly on wound, then light gauze (not bulky). NO PRESSURE DRESSING. Check digital perfusion - capillary refill should be less than 2 seconds, fingertip pink.

Exam Pearl

Technical Tip: EXAM KEY - Skin closure must be meticulous and tension-free. Bruner incisions: close zigzag apices first with simple interrupted or vertical mattress, then close sides. Ensures proper alignment of zigzag pattern. Some surgeons use absorbable subcuticular 5-0 Monocryl for better cosmesis (no suture removal needed). Check perfusion after closure and dressing - if dusky or slow capillary refill, remove dressing and recheck (may be too tight or vascular injury).

Dangers at this step

Tension on skin edges (flap necrosis, especially at zigzag apex)
Haematoma under flaps (lifts skin from underlying tendon)
Vascular compromise from tight dressing (compartment syndrome)
Inverting skin edges (poor healing, wide scar)

Step 11: Splint Application - Dorsal Blocking Splint

Apply DORSAL BLOCKING SPLINT immediately in operating room. Position: (1) Wrist 20-30 degrees FLEXION, (2) MCPJs 70-80 degrees FLEXION, (3) IPJs 0 degrees (FULL EXTENSION - critical point). Use thermoplastic splint material, mold dorsally (blocks extension but allows flexion). Splint should allow patient to make full fist (full composite flexion) but blocks wrist and MCPJ extension passively. This position places flexor tendons in slack (protected position) while preventing PIP contracture.

Exam Pearl

Technical Tip: EXAM KEY - Splint position often misunderstood. WRIST and MCPs flexed (protects repair from tension), but IPJs in EXTENSION (prevents PIP contracture). Patient CAN flex fingers fully within splint (makes fist), but CANNOT extend wrist or MCPs (splint blocks this dorsally). Alternative: Kleinert splint with rubber band traction from nail to palmar wrist band (allows passive flexion, blocks active extension). Early active motion protocol allows active flexion within dorsal blocking splint.

Dangers at this step

Wrong position (IPJs flexed instead of extended - causes PIP contracture)
Volar splint instead of dorsal (restricts active flexion)
Too tight (compartment syndrome, pressure sores)
Insufficient MCPJ flexion (less than 60 degrees - inadequate protection)
Inadequate blocking (patient extends against splint, ruptures repair)

Step 12: Post-Operative Rehabilitation Protocol Initiation

Initiate EARLY ACTIVE MOTION protocol within 3-5 days post-operatively (requires strong repair - 4-6 strand plus epitendinous). Hand therapist educates patient: active flexion exercises within dorsal blocking splint protection (make fist - full composite flexion), then passive extension (therapist-assisted or self with other hand). 10 repetitions every waking hour (8-10 sessions daily). Place-and-hold exercises (flex and maintain position 5 seconds). Splint remains on continuously except during supervised therapy sessions. Monitor weekly for complications.

Exam Pearl

Technical Tip: EXAM KEY - Early active motion = GOLD STANDARD, reduces adhesions 50% vs immobilization. Requirements: (1) Strong repair greater than 50N, (2) Compliant motivated patient, (3) Expert hand therapist, (4) Close monitoring weekly first month. Teach patient difference between active flexion (making fist - ALLOWED and encouraged) vs active extension (straightening fingers - BLOCKED by splint). Rupture risk 2-5% but worthwhile for significant adhesion reduction. Alternative: passive motion (Kleinert) if compliance concerns.

Dangers at this step

Non-compliance (patient removes splint, extends forcefully - rupture)
Inadequate therapy supervision (wrong exercises, too aggressive)
Too aggressive too early (rupture, typically weeks 2-4 highest risk)
Too conservative (excessive caution leads to adhesions)
Missing therapy appointments (adhesions develop quickly)

Step 13: Assessment of Repair Strength and Quality

Before closing, document repair quality systematically: (1) Visual inspection - no gap, smooth contour, no suture bunching; (2) Passive ROM - smooth gliding through pulleys without catching; (3) Resistance testing - gentle traction on proximal tendon (should hold 30-40N without gapping); (4) Cascade check - finger rests in normal cascade with wrist neutral. Photograph for documentation. Classify repair: OPTIMAL (6-strand plus epitendinous plus pulleys intact), GOOD (4-strand plus epitendinous plus greater than 80% pulleys), ACCEPTABLE (4-strand plus partial epitendinous), SUBOPTIMAL (less than 4 strands or greater than 50% pulley loss).

Exam Pearl

Technical Tip: EXAM KEY - Repair quality classification determines rehabilitation protocol. OPTIMAL/GOOD = early active motion protocol. ACCEPTABLE = modified active or passive protocol. SUBOPTIMAL = consider converting to staged reconstruction (Hunter rod then tendon graft). Document clearly in operative note for hand therapist. Include: number of strands, suture type, percentage of A2 and A4 preserved, FDS management (repaired vs excised), estimated repair strength, recommended protocol. Photos helpful for later reference.

Dangers at this step

Overestimating repair strength (prescribe too aggressive protocol - rupture)
Poor documentation (therapist doesn't know what was done - wrong protocol)
Missing quality issues before closing (gap, catching, bowstringing)
Failing to communicate with therapist (no handoff of critical information)

Step 14: Management of Combined Injuries

If combined injuries present (flexor tendon plus digital nerve and/or artery and/or fracture), manage systematically. Priority sequence: (1) Skeletal stability first if fracture present (K-wire or mini-plate fixation), (2) Arterial repair if both arteries cut (need minimum one patent artery per digit), (3) Flexor tendon repair (most time-consuming), (4) Digital nerve repair (if both nerves cut). Tendon repair technically easier position before nerve repair. Combined injuries have worse prognosis (more scarring, adhesions). Document all repairs. Consider modified passive motion protocol.

Exam Pearl

Technical Tip: EXAM KEY - Combined injury significantly worsens prognosis (good results drop from 75-85% to 50-60%). More structures injured = more scarring = more adhesions. Repair sequence matters for efficiency and outcomes. FRACTURE first (stable skeleton allows easier soft tissue repair). ARTERY if both cut (need perfusion, but single artery adequate). TENDON next (takes longest, do before nerve so can tension tendon without pulling nerve). NERVE last (if both nerves cut on one side digit - single nerve cut may skip, clean cut better than coaptation scar).

Dangers at this step

Missing concurrent injuries during initial assessment (devastating)
Wrong repair sequence (compromises individual repairs)
Arterial insufficiency (fingertip necrosis if both arteries not repaired/intact)
Over-bulking from multiple repairs (severe triggering and adhesions)

Step 15: Documentation and Patient Education

Complete thorough operative documentation: (1) Zone of injury, (2) Structures injured with percentages (FDP complete, FDS 75%, radial nerve partial), (3) Repair technique specifics (Adelaide 6-strand with FiberWire 3-0, running cross-stitch epitendinous 6-0 Prolene), (4) Pulley status (A2 100% preserved, A4 75% preserved, all C pulleys vented), (5) Repair quality classification (OPTIMAL/GOOD/ACCEPTABLE), (6) Recommended protocol (early active motion vs passive vs other). EDUCATE patient extensively: critical importance of therapy compliance, signs of rupture (sudden loss of flexion, palpable gap, pop sensation), signs of infection (Kanavel's four signs), expected timeline (6 weeks splint, 12 weeks full function), realistic expectations (75-85% good results, 10% re-rupture, 15% may need tenolysis).

Exam Pearl

Technical Tip: EXAM KEY - Patient education CRITICAL for success. Many failures due to non-compliance or unrealistic expectations. Set clear expectations: (1) Intensive hand therapy for minimum 3 months, (2) May not regain full ROM (expect 80-90% of normal even with optimal repair), (3) 15-20% need second surgery (tenolysis for stiffness or re-repair/reconstruction for rupture), (4) Manual work return 3-4 months minimum, heavy labor 4-6 months. RED FLAGS to report immediately: sudden loss of flexion (rupture), visible gap in finger, increasing pain with fusiform swelling (infection), severe sensitivity (CRPS). Arrange first therapy session within 5 days maximum.

Dangers at this step

Inadequate documentation (therapist lacks critical information about repair)
Poor patient education (non-compliance from misunderstanding)
No therapy arranged before discharge (adhesions develop early)
Unrealistic expectations set (patient disappointed with normal outcome)
Failure to provide written instructions (patient forgets verbal instructions)

Complications - Recognition and Management

Major Complications of Zone 2 Flexor Tendon Repair

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 28-year-old chef presents 6 hours after cutting his right long finger with a sharp knife. He has lost active flexion at the DIPJ and PIPJ. Describe your management including surgical technique."

EXCEPTIONAL ANSWER

This is an acute Zone 2 flexor tendon injury requiring primary surgical repair. I would systematically approach this as follows: **Initial Assessment**: Confirm complete FDP and FDS lacerations by examining active ROM (unable to flex DIPJ = FDP cut, unable to flex PIPJ = FDS cut) and passive ROM (should be full). Check neurovascular status (two-point discrimination, capillary refill, Allen's test). X-ray to exclude foreign body or fracture. **Surgical Planning**: Repair within 24-48 hours ideally (up to 7-10 days acceptable). Regional or general anesthesia. Tourniquet control. Discuss realistic expectations (75-85% good results, 10% may rupture, 15% may need tenolysis, intensive therapy for 3 months required). **Operative Technique**: Extend laceration with Bruner zigzag incisions (60-degree angles to creases). Preserve digital neurovascular bundles. Open flexor sheath preserving A2 and A4 pulleys (critical for preventing bowstringing). Vent all C pulleys. Retrieve proximal tendon ends (FDP may retract to palm - use pediatric feeding tube technique if needed). Minimal debridement to preserve length. **Repair Technique**: FDP repair MANDATORY using 6-strand Adelaide technique with 3-0 or 4-0 braided non-absorbable (FiberWire or Ethibond). Locking loops purchasing 7-10mm from cut edge. Running epitendinous with 6-0 Prolene (adds 10-50% strength, creates smooth surface). FDS: repair one slip with 4-strand technique, excise one slip to reduce bulk. Check smooth gliding through pulleys. Loose sheath closure with vents. **Post-operative**: Dorsal blocking splint (wrist 20-30° flexion, MCPs 70-80° flexion, IPJs 0° extension). Early active motion protocol starting day 3-5: active flexion within splint protection, passive extension, 10 reps hourly. Weekly hand therapy monitoring. Splint for 6 weeks total.

VIVA SCENARIOStandard

EXAMINER

"You are repairing a Zone 2 flexor tendon injury and intraoperatively notice the repair catches and triggers as it passes through the A2 pulley. What are the causes and how would you address this?"

EXCEPTIONAL ANSWER

Intraoperative catching is a critical finding that MUST be addressed before closure - if the repair catches with passive motion under direct vision, it will definitely trigger post-operatively leading to adhesions and likely rupture. I would systematically troubleshoot: **Immediate Assessment**: Test passive finger flexion/extension repeatedly while visualizing tendon gliding through A2 pulley under loupe magnification. Identify exact location of catching (proximal, middle, or distal A2, or elsewhere). **Common Causes**: (1) Core suture knots creating bulk - especially if knots placed on tendon surface rather than buried, (2) Epitendinous suture bunching - if bites too deep or tension uneven, creates irregular surface, (3) Insufficient pulley venting - C pulleys not adequately opened, (4) Bulky repair - both FDS slips plus FDP in tight sheath, (5) Pulley edge catching - if pulley cut edge sharp or partially avulsed. **Systematic Solutions**: - FIRST: Check core suture knots - should be buried within substance of tendon, not on surface. If surface knots, may need to redo core suture with better knot placement. - SECOND: Assess epitendinous - look for bunching or irregular areas. May need to remove and redo epitendinous more carefully with shallower bites and even tension. - THIRD: Vent ALL C pulleys completely if not already done (C1, C2, C3 can all be sacrificed). - FOURTH: If still catching on A2 and repair is bulky, consider venting distal 25% of A2 pulley (MUST preserve central and proximal 50%). - FIFTH: If FDS contributing to bulk, consider excising one or both FDS slips. - SIXTH: Smooth any sharp edges on pulley remnants with micro-scissors. **Test and Retest**: After each modification, test passive gliding again. Must achieve completely smooth gliding before closing. **Documentation**: Document catching and resolution in operative note. If had to vent significant A2 or A4, this affects post-operative management (may need modified protocol, consider pulley reconstruction at later stage if bowstringing develops).

VIVA SCENARIOStandard

EXAMINER

"A 35-year-old manual laborer had Zone 2 flexor tendon repair 3 weeks ago with early active motion protocol. He now presents with sudden loss of active DIPJ flexion after lifting a heavy box. Examination shows no active FDP function. Discuss your management options and their outcomes."

EXCEPTIONAL ANSWER

This is a flexor tendon repair RUPTURE - a devastating complication occurring in 2-5% of repairs (peak risk weeks 2-4 when tendon weakest). Management depends on timing, patient factors, and goals. **Confirmation of Diagnosis**: Clinical exam confirms (loss of active DIPJ flexion, palpable gap, unable to flex DIP with PIP held extended). Ultrasound or MRI can confirm tendon discontinuity and estimate gap size, but diagnosis is clinical. Assess: exact location of rupture, size of gap (less than 3mm vs greater than 3mm), tendon end location (in finger vs retracted to palm), other structures (nerve, artery intact). **Management Options**: **Option 1 - Direct Re-Repair** (if within days of rupture, tendon ends in finger): - URGENTLY explore within 48-72 hours before significant retraction - Retrieve tendon ends, minimal debridement of scar tissue - Repair with strongest technique possible (6-strand core plus epitendinous) - PROBLEM: High failure rate (30-40% re-rupture) due to: - Scar tissue = poor tendon quality - Gap from retraction = tension on repair - Adhesions already forming = limited gliding - Post-op: More conservative protocol (passive motion only for 4-6 weeks) - I would generally NOT recommend re-repair except in highly selected cases (early presentation, minimal gap, young patient, strong tissue) **Option 2 - Staged Tendon Reconstruction** (PREFERRED in most cases): - Counsel patient this is TWO operations minimum 3-4 months apart - STAGE 1 (now): Insert Hunter silicone rod through flexor sheath, reconstruct any damaged pulleys using slip of A2 remnant or extensor retinaculum graft, passive motion protocol for 3-4 months to create gliding pseudosheath around rod - STAGE 2 (3-4 months later): Remove rod, pass tendon graft (palmaris longus preferred, alternatives: plantaris, toe extensor, allograft), weave graft into distal phalanx and proximally into FDP muscle belly or palm, similar repair technique and rehab as primary - SUCCESS: 60-75% achieve good/excellent results (worse than primary repair but reasonable salvage) - Return to work delayed 6-9 months total **Option 3 - Tendon Transfer**: - FDS-to-FDP transfer: detach FDS from insertion, pass through FDP at level of A1, suture under tension - INDICATION: If staged reconstruction not feasible (pulley damage, scarring), single digit injury - SUCCESS: 60-70% good results, loses PIPJ independent flexion - Faster recovery than staged (3-4 months) **Option 4 - Accept Loss** (RARE): - PIPJ arthrodesis in functional position with DIP free - Only if: Patient refuses further surgery, significant comorbidities, manual laborer who values stability over motion - Functional limitations significant **My Recommendation**: For this patient (35-year-old manual laborer, 3 weeks post-op, acute rupture), I would recommend STAGED RECONSTRUCTION as best chance of good functional outcome. Counsel realistic expectations: 60-75% good results (worse than if primary repair had succeeded), two operations, 6-9 months total recovery, may still need tenolysis (15-20% chance). Discuss work limitations and possible need for job modification.