import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **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 **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 **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 **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 **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 ## 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 ## Indications for Primary Repair **Absolute Indications**: - Acute complete FDP laceration in Zone 2 (<7-10 days old) - Partial FDP laceration greater than 50% cross-sectional area - Combined FDP and FDS complete lacerations - Clean sharp injury (knife, glass) with minimal contamination - Patient medically fit for surgery and anesthesia - Patient able to comply with post-operative therapy **Relative Indications**: - Acute FDS laceration alone (controversial - can observe) - Subacute injuries 10-21 days (healing process begun but may still achieve primary repair) - Partial lacerations 25-50% (may heal without repair if FDP intact, but risk of triggering) - Tendon injuries with associated digital nerve or artery injuries (repair together) **Favorable Prognostic Factors**: - Sharp clean laceration (knife injury) - Single structure injury (tendon only) - Presentation within 48 hours of injury - Young motivated patient - No crush component to injury - Index or long finger (function better than ring/small) ## Contraindications **Absolute Contraindications**: - Active infection (pyogenic flexor tenosynovitis) - drain first, delayed reconstruction - Severe crush injury with devitalized tissue - staged reconstruction preferred - Extensive soft tissue loss preventing skin closure - Patient unable to comply with therapy protocol (cognitive impairment, severe psychiatric disease) - Medical comorbidities precluding safe surgery (unstable cardiac disease, coagulopathy) - Severe underlying inflammatory arthropathy (rheumatoid) - repair likely to fail **Relative Contraindications**: - Delayed presentation greater than 3 weeks (tendon retraction, scarring - consider staged) - Human/animal bite injury (high infection risk - irrigate, antibiotics, delayed repair in 3-5 days) - Multiple digit involvement (prolonged surgery, consider staged approach) - Heavy smoker (higher complication rate, poorer healing) - Diabetes mellitus with neuropathy (higher infection risk, poorer wound healing) - Previous failed flexor tendon repair in same digit (consider staged reconstruction) - Significant arthritis of IPJ (repair won't improve function if joint destroyed) ## Timing Considerations **Acute Repair** (0-7 days): - IDEAL timing - Tendon ends fresh and easy to identify - Minimal scarring and retraction - Best functional outcomes **Subacute Repair** (7-21 days): - Still possible but technically harder - Some tendon retraction begins - Early scar formation - May need more extensive dissection **Delayed Primary Repair** (21 days to 6 weeks): - Very challenging technically - Significant retraction and scarring - Often require tendon retrieval from palm or forearm - Consider staged reconstruction instead **Chronic** (greater than 6 weeks): - Primary repair NOT recommended - Proceed to staged reconstruction with Hunter rod or tendon graft - Or consider tendon transfer (FDS to FDP transfer) ## Patient Positioning and Setup **Patient Position**: - Supine on operating table - Arm extended on radiolucent hand table (for fluoroscopy if needed) - Shoulder abducted 80-90 degrees - Elbow extended, hand supinated - High arm tourniquet at 250mmHg (exsanguinate with Esmarch or elevation) **Anesthesia Options**: - General anesthesia (preferred for complex repairs or anxious patients) - Brachial plexus block (axillary or supraclavicular) - allows awake patient cooperation - Wide awake local anesthesia no tourniquet (WALANT) - 1% lidocaine with 1:100,000 epinephrine - Advantages: Can test active motion intraoperatively, no tourniquet pain, outpatient procedure - Disadvantages: Field of view slightly compromised, not suitable for all patients **Equipment Needed**: - Loupe magnification (2.5x to 3.5x recommended) or microscope (4-6x) - Fine instruments (Adson forceps, micro scissors, fine needle holders) - Pediatric feeding tube or 6Fr infant catheter (for tendon retrieval) - 3-0 or 4-0 braided non-absorbable suture (Ethibond, Ticron, FiberWire) - 5-0 or 6-0 monofilament (Prolene, Nylon) for epitendinous - Vessel loops for NV bundle retraction - Thermoplastic splint material for dorsal blocking splint ## Incision Options **Bruner Zigzag Incision** (PREFERRED): - Zigzag pattern with angles 60 degrees to flexion creases (NEVER 90 degrees) - Apex of each zigzag at midaxial line - Each segment 5-8mm in length - Can extend proximally into palm with further zigzags - Advantages: Crosses creases obliquely (prevents contracture), excellent exposure - Disadvantages: Technically more demanding, risk of skin flap necrosis if too narrow **Midlateral Incision** (ALTERNATIVE): - Longitudinal incision along midaxial line - Remains on radial or ulnar side of digit - Does not cross flexion creases - Advantages: Simpler, safer for skin, preserves one NV bundle unviolated - Disadvantages: More limited exposure, harder to access both tendons, may need to sacrifice FDS **Volar Longitudinal** (AVOID): - Straight longitudinal incision in midline of finger - Crosses flexion creases perpendicularly - CONTRAINDICATED - causes hypertrophic scarring and flexion contracture - Only acceptable if parallels existing longitudinal scar ## Core Suture Techniques **2-Strand Techniques** (30N strength - INADEQUATE for early active): - Modified Kessler - Bunnell - Historically standard, now superseded by multi-strand **4-Strand Techniques** (40-50N strength - MINIMUM for early active): - Cruciate (Strickland) - Double modified Kessler - Savage technique (if done as 4-strand variant) **6-Strand Techniques** (60-80N strength - PREFERRED): - Adelaide technique (most popular) - Savage 6-strand - M-Tang technique - Provides highest strength for early active motion **Technical Principles for All Core Sutures**: - Purchase tendon 7-12mm from cut edge (prevents cheese-wiring) - Use LOCKING configuration (20-30% stronger than grasping) - Ensure NO GAP at repair site (less than 1mm acceptable) - Equal tension on all strands - Bury knots to prevent surface irregularity - Non-absorbable braided suture (3-0 or 4-0) ## Epitendinous Suture Techniques **Running Simple Suture**: - Continuous running around circumference - 5-0 or 6-0 monofilament - Bites 0.5-1mm deep, 2mm apart - Start 180 degrees from core knot **Cross-Stitch (Lin) Technique**: - Running locked suture in figure-of-8 pattern - Superior strength to simple running - Creates very smooth surface **Halstead Technique**: - Modified running with locking bites - Good balance of strength and smoothness **Technical Principles**: - MANDATORY component (not optional) - Adds 10-50% to core suture strength - Creates smooth gliding surface - Buries core suture knots - Prevents gap formation - Keep bites shallow (avoid devascularization) ## FDS Management Strategies **Option 1 - Repair Both FDS Slips**: - If sheath capacious and ample space - Provides maximum PIPJ flexion power - Risk of over-bulking and adhesions - Preferred in ring/small fingers (need independent PIPJ flexion) **Option 2 - Repair One Slip, Excise One**: - COMPROMISE approach (most common) - Usually excise ulnar/volar slip - Balances bulk with some FDS function - Remove excised slip completely (don't leave stumps) **Option 3 - Excise Both FDS Slips**: - Some surgeons prefer in tight Zone 2 - Reduces bulk and adhesion formation - Fingers function well with FDP alone (especially index/long) - Excise distal to chiasm, remove completely to A1 pulley **Decision Factors**: - Finger involved (index/long tolerate FDS loss better) - Sheath capacity (tight vs capacious) - Extent of sheath injury - Surgeon preference and experience ## Early Active Motion Protocol (Gold Standard) **Requirements**: - Strong repair (4-6 strand core + epitendinous, greater than 50N) - Motivated compliant patient - Expert hand therapist available - Close monitoring (weekly initially) **Timeline**: **Day 0-2** (Immediate post-op): - Dorsal blocking splint applied in OR - Position: Wrist 20-30° flexion, MCPs 70-80° flexion, IPJs 0° extension - Hand elevated continuously above heart - Ice, pain control **Day 3-5** (Early active motion begins): - Remove bulky dressing - Start exercises within splint protection: - Active flexion: Make fist (full composite flexion) - Passive extension: Therapist-assisted or rubber band - 10 repetitions every waking hour (8-10 sessions/day) - Place-and-hold exercises (maintain flexion 5 seconds) **Week 1-4**: - Splint worn continuously (only off for therapy) - Progress active flexion force gradually - Add blocking exercises (isolate FDP and FDS) - Weekly therapy sessions with ROM goniometry - Monitor for complications (rupture, adhesions, triggering) - Sutures removed day 10-14 **Week 4-6**: - Continue full-time splint - Start gentle passive extension out of splint (therapist supervised) - Progress to home passive extension program - Differential gliding exercises **Week 6-8**: - WEAN splint - start daytime off (1-2 hours, progress to full day) - Continue nighttime splint protection - Progressive active ROM exercises - Light functional ADLs **Week 8-10**: - Discontinue splint entirely - Start gentle strengthening (soft therapist putty) - Light gripping exercises **Week 10-12**: - Progress resistance (graded putty, hand gripper) - Functional work simulation - Week 12: Return to unrestricted activities **Manual laborers**: May need 14-16 weeks for full heavy duties ## Alternative Protocols **Modified Kleinert (Passive Motion)**: - Rubber band traction from fingernail to palmar wrist band - Allows passive flexion, active extension blocked - Less demanding than early active - Use if: Repair strength questionable, patient compliance concerns - Adhesion rate higher than early active (15-25% vs 10-15%) **Controlled Active Motion (Place and Hold)**: - Limited arc active flexion (to distal palmar crease only) - Place-and-hold exercises (no forceful flexion) - Intermediate between passive and full active - Good compromise for moderate strength repairs **Immobilization Protocol**: - Splint in protective position for 3 weeks - Then start passive motion only for 3 more weeks - Active motion after 6 weeks - HIGHEST adhesion rate (30-40%) - Reserve for: Very weak repairs, poor compliance, combined injuries - Essentially abandoned in modern practice ## Monitoring and Progression Criteria **Weekly Assessment (Weeks 1-4)**: - Active flexion ROM (measure fingertip to distal palmar crease) - Passive extension ROM (measure extension deficit each joint) - Check for rupture signs (sudden loss of flexion, palpable gap) - Check for infection (Kanavel's signs) - Check for triggering (catching sensation) - Check for PIP contracture (extension deficit) **Biweekly Assessment (Weeks 4-8)**: - ROM measurements with goniometry - Assess quality of motion (smooth vs jerky) - Strength testing (light resistance only) **Monthly Assessment (Weeks 8-12)**: - ROM (compare to contralateral hand) - Grip strength (Jamar dynamometer) - Pinch strength (pinch gauge) - Functional assessment (Jebsen-Taylor Hand Function Test) **Red Flags Requiring Urgent Assessment**: - Sudden loss of active flexion (rupture) - Severe increasing pain (infection, CRPS) - Locking or severe triggering - Progressive PIP contracture (greater than 20 degrees) - Signs of infection (Kanavel's signs) **Plateau in ROM** (failure to progress): - If ROM less than 50% normal at 3 months despite optimal therapy - Consider tenolysis at 4-6 months minimum - Allow scar maturation before tenolysis ## Repair Technique Outcomes **Multi-Strand Core Suture Evidence**: - Systematic reviews show 6-strand repairs have: - Lower rupture rates (2-4% vs 5-10% for 4-strand) - Higher strength allowing more aggressive therapy - Similar adhesion rates to 4-strand - Adelaide technique most studied with best outcomes **Epitendinous Suture Evidence**: - Meta-analyses confirm: - Adds 10-50% to repair strength (average 25%) - Reduces gap formation at repair site - Creates smoother gliding surface - Reduces triggering and catching - Cross-stitch techniques superior to simple running **FDS Management Evidence**: - No consensus - studies show: - Both slips repaired: Better grip strength, higher bulk/adhesions - One slip repaired: Good compromise, most common practice - Both slips excised: Lower adhesions, adequate function in index/long - No significant difference in DASH scores at 1 year between strategies ## Rehabilitation Protocol Evidence **Early Active Motion vs Immobilization**: - Cochrane Review (2015): - Early active motion reduces adhesions significantly - Better total active motion (TAM) at 6 and 12 months - Slightly higher rupture rate (4% vs 2%) but worthwhile tradeoff - 75-85% achieve good/excellent results with early active - Need strong repair (greater than 50N) for safety **Early Active vs Passive Motion**: - Multiple RCTs show: - Early active superior to passive for final ROM - Rupture rates similar if repair strength adequate (4-5%) - Patient satisfaction higher with early active - Earlier return to work/function **Timing of Motion Initiation**: - Starting within 3-5 days optimal - Delays beyond 2 weeks increase adhesions significantly - No benefit to starting day 0-1 vs day 3-5 ## Functional Outcomes **Good/Excellent Results** (Various Scoring Systems): - Strickland Criteria: 75-85% achieve good/excellent - Good = TAM greater than 50% of normal - Excellent = TAM greater than 75% of normal - Buck-Gramcko Score: Similar results - DASH Score: Mean 10-15 (population mean ~10, lower is better) **Factors Predicting Better Outcomes**: - Sharp clean laceration (vs crush) - Single structure injury (vs combined) - Timely repair (less than 7 days) - Strong repair technique (6-strand) - Early active motion protocol - Expert hand therapy - Patient compliance - Young age (under 40 years) - Index or long finger (vs ring/small) **Factors Predicting Poorer Outcomes**: - Crush mechanism - Combined injuries (nerve, artery, bone) - Delayed repair (greater than 14 days) - Significant pulley loss (greater than 50% of A2 or A4) - Infection - Non-compliance with therapy - Older age (greater than 60 years) - Smoking - Diabetes - Manual laborer (higher functional demands) ## Complication Rates **Overall Complication Rate**: 25-35% (but most minor) **Specific Complications**: - Adhesions requiring tenolysis: 15-25% - Rupture: 2-5% (with modern strong repairs) - PIP contracture greater than 20 degrees: 10-20% - Triggering (significant): 5-10% - Infection: 1-3% - CRPS Type 1: 2-5% - Need for secondary procedure: 20-30% ## Return to Function Timeline **Light Work/ADLs**: 6-8 weeks **Moderate Work**: 10-12 weeks **Heavy Manual Labor**: 14-16 weeks **Contact Sports**: 12-16 weeks **Plateau of Recovery**: 6-9 months (maximum medical improvement) ### 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. **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. - 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. **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. - 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. **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. - 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. **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). - 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). **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). - 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. **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. - 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. **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. - 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. **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. - 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. **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. - 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. **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). - 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. **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. - 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. **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. - 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). **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. - 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. **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). - 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). **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. - 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) ## References 1. Strickland JW. Development of flexor tendon surgery: twenty-five years of progress. J Hand Surg Am. 2000;25(2):214-235. doi:10.1053/jhsu.2000.jhsu25a0214 - *Seminal review of flexor tendon repair evolution and Strickland criteria for outcome assessment* 2. Tang JB. Clinical outcomes associated with flexor tendon repair. Hand Clin. 2005;21(2):199-210. doi:10.1016/j.hcl.2004.11.005 - *Comprehensive analysis of factors affecting flexor tendon repair outcomes and evidence-based techniques* 3. Savage R, Risitano G. Flexor tendon repair using a "six strand" method of repair and early active mobilisation. J Hand Surg Br. 1989;14(4):396-399. doi:10.1016/0266-7681(89)90152-6 - *Original description of 6-strand repair technique providing superior strength for early active motion* 4. Elliot D, Moiemen NS, Flemming AF, et al. The rupture rate of acute flexor tendon repairs mobilized by the controlled active motion regimen. J Hand Surg Br. 1994;19(5):607-612. doi:10.1016/0266-7681(94)90123-6 - *Large series establishing 4-5% rupture rate with early active motion protocols using strong multi-strand repairs* 5. Winters SC, Gelberman RH, Woo SL, et al. The effects of multiple-strand suture methods on the strength and excursion of repaired intrasynovial flexor tendons: a biomechanical study in dogs. J Hand Surg Am. 1998;23(1):97-104. doi:10.1016/S0363-5023(98)80095-6 - *Biomechanical study demonstrating superiority of 4-strand and 6-strand repairs over 2-strand techniques* 6. Lin GT, An KN, Amadio PC, Cooney WP 3rd. Biomechanical studies of running suture for flexor tendon repair in dogs. J Hand Surg Am. 1988;13(4):553-558. doi:10.1016/S0363-5023(88)80093-0 - *Demonstrates epitendinous suture adds 10-50% to repair strength and creates smooth gliding surface* 7. Silfverskiöld KL, May EJ. Early active mobilization of tendon repairs: experimental study of the effect of early active mobilisation on tendon healing. Hand Clin. 1993;9(1):59-64. - *Evidence supporting early active motion reducing adhesions compared to immobilization or passive protocols* 8. Pettengill KM. The evolution of early mobilization of the repaired flexor tendon. J Hand Ther. 2005;18(2):157-168. doi:10.1197/j.jht.2005.02.011 - *Comprehensive review of rehabilitation protocol evolution and evidence for early active motion* 9. Lilly SI, Messer TM. Complications after treatment of flexor tendon injuries. J Am Acad Orthop Surg. 2006;14(7):387-396. doi:10.5435/00124635-200607000-00002 - *Systematic review of complications including adhesions, rupture, PIP contracture with evidence-based management strategies* 10. Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report. Adelaide: AOA; 2023. *Australian registry data on outcomes and complications (adapted for hand surgery evidence-based practice context)*

Flexor Tendon Repair - Zone 2

Flexor Tendon Repair - Zone 2