Volar and Dorsal Forearm Fasciotomy

Forearm Compartment Syndrome - Recognition and Decision-Making

High-Risk Injuries

Pediatric:

• Supracondylar humerus fractures (most common cause in children - 10-20% risk)
• Both-bone forearm fractures with significant displacement
• Floating elbow (ipsilateral humerus and forearm fractures)

Adult:

• Both-bone forearm fractures (radius and ulna)
• Isolated radius or ulna fractures with severe soft tissue injury
• Crush injuries (machinery, motor vehicle collision)
• Prolonged limb ischemia (brachial artery injury with delayed repair)
• Ischemia-reperfusion injury after revascularization
• Burns (circumferential eschar)
• Tight casts or dressings
• Snake bites (rare but recognized)

Clinical Diagnosis - CRITICAL

Five Ps (late signs - do not wait for all):

1. Pain - out of proportion to injury, progressive
2. Pain on passive stretch - MOST RELIABLE early sign
3. Pressure - tense, swollen forearm compartments on palpation
4. Paresthesias - median nerve most sensitive (thumb-index numbness, thenar weakness)
5. Pulselessness - LATE sign (compartment syndrome can occur with intact pulses)
6. Pallor - LATE sign
7. Paralysis - LATE sign (indicates severe ischemia)

Key Clinical Findings:

• Pain on passive finger extension (stretches volar compartment) - EARLIEST sign
• Pain on passive finger flexion (stretches dorsal compartment)
• Tense, swollen forearm (compartments firm on palpation)
• Progressive pain despite adequate analgesia
• Median nerve symptoms (most sensitive) - thenar weakness, thumb-index numbness
• Ulnar nerve symptoms - intrinsic weakness, ulnar-sided numbness
• Radial nerve symptoms - wrist drop, thumb extension weakness

Associated Carpal Tunnel Syndrome

Timing - Critical Factor

• Less than 6 hours: Excellent prognosis with early fasciotomy
• 6-12 hours: Good prognosis if immediate fasciotomy
• 12-24 hours: Permanent damage likely, Volkmann's contracture risk
• More than 24 hours: Established Volkmann's contracture, fasciotomy may not help

EXAM ANSWER: "Forearm compartment syndrome is a CLINICAL DIAGNOSIS - I do not wait for pressure measurements. Classic presentation: pain out of proportion, tense forearm, pain on passive finger extension (stretches volar compartment - earliest sign). High-risk injuries include supracondylar fractures in children and both-bone forearm fractures. I assess for concurrent carpal tunnel syndrome (20-30% of cases) - if present, I release carpal tunnel first. Timing critical - fasciotomy within 6 hours gives excellent prognosis, delay beyond 12 hours risks permanent Volkmann's contracture."

Forearm Compartments and Neurovascular Anatomy

Three (Four) Compartments

1. Volar Superficial Compartment:

• Muscles: Pronator teres, FCR (flexor carpi radialis), palmaris longus (15% absent), FCU (flexor carpi ulnaris)
• Nerves: Median nerve (runs between FDS tendons), ulnar nerve (under FCU at ulnar border)
• Vessels: Radial artery (radial border, between BR and FCR), ulnar artery (with ulnar nerve)
• Borders: Antebrachial fascia (superficial), FDS muscle (deep)

2. Volar Deep Compartment:

• Muscles: FDP (flexor digitorum profundus - ulnar four fingers), FPL (flexor pollicis longus - thumb), pronator quadratus (distal forearm)
• Nerves: Median nerve (between FDS and FDP), anterior interosseous nerve (motor branch on interosseous membrane)
• Vessels: Anterior interosseous artery (with AIN on interosseous membrane)
• Borders: FDS (superficial), interosseous membrane (deep)

3. Dorsal/Extensor Compartment:

• Muscles: Superficial (ECRL, ECRB, EDC, EDM, ECU) and Deep (APL, EPB, EPL, EIP)
• Nerves: Posterior interosseous nerve (motor branch, deep between layers), superficial radial nerve (sensory, becomes subcutaneous distal third)
• Vessels: Posterior interosseous artery
• Borders: Extensor fascia (superficial), interosseous membrane (deep)

4. Mobile Wad (Radial/Lateral Compartment):

• Muscles: Brachioradialis (elbow flexion), ECRL and ECRB (wrist extension)
• Nerves: Radial nerve (deep proximally, becomes superficial 8-10cm above wrist between BR and ECRL)
• Vessels: Radial recurrent artery proximally
• Borders: Between volar and dorsal compartments on radial side

Critical Neurovascular Anatomy

Median Nerve:

• Enters forearm between two heads of pronator teres
• Runs between FDS (superficial) and FDP (deep) in volar compartment
• Approximately 2cm radial to midline in mid-forearm
• MOST SENSITIVE to ischemia - first to show symptoms
• Gives off anterior interosseous nerve (AIN) 5cm distal to medial epicondyle
• AIN is pure motor: FPL, radial FDP (index/middle), pronator quadratus

Ulnar Nerve:

• Enters forearm between two heads of FCU
• Runs along ulnar border between FCU (superficial) and FDP (deep)
• Accompanied by ulnar artery
• Enters hand through Guyon's canal (between pisiform and hook of hamate)
• Both motor (intrinsics, hypothenar) and sensory (ulnar 1.5 digits)

Radial Nerve:

• Divides into deep (posterior interosseous - PIN) and superficial branches at level of radiocapitellar joint
• PIN: pure motor, deep to supinator, innervates all extensors except ECRL
• Superficial radial: pure sensory, deep to brachioradialis proximally
• Becomes subcutaneous 8-10cm proximal to wrist between BR and ECRL tendons
• Provides sensation to radial dorsum of hand

Radial Artery:

• Radial border of forearm between brachioradialis and FCR
• Becomes superficial at wrist 5cm proximal to radial styloid
• REASON for ulnar volar approach - radial approach risks radial artery injury

Surgical Approaches - Rationale

Volar Ulnar Approach:

• PREFERRED volar approach
• Avoids radial artery completely
• Median nerve ~2cm radial to incision - easier to identify and protect
• Access to both volar superficial and deep compartments
• Can extend to palm for carpal tunnel release

Dorsal Approach:

• Releases dorsal/extensor compartment
• Provides access to mobile wad
• Superficial radial nerve at risk in distal third (becomes subcutaneous)
• Relatively straightforward - fewer critical structures than volar

EXAM ANSWER: "Forearm has THREE main compartments: Volar superficial (PT, FCR, PL, FCU), volar deep (FDP, FPL, PQ), and dorsal/extensor (all wrist and finger extensors). Mobile wad (BR, ECRL, ECRB) is often considered a fourth compartment. I use ULNAR volar approach for volar compartments - starts 2cm distal-medial to medial epicondyle, extends along ulnar forearm. This is safer than radial approach - avoids radial artery and reduces median nerve injury risk. Median nerve runs between FDS and FDP ~2cm radial to ulnar incision. Dorsal incision releases extensor compartment and mobile wad. All compartments must be assessed and released."

Step-by-Step Surgical Technique

Patient Preparation

Positioning:

• Supine with affected arm on radiolucent hand table
• Arm abducted approximately 90 degrees
• Entire upper extremity prepped from shoulder to fingertips
• Sterile draping allows full visualization from shoulder to hand

Equipment:

• No tourniquet inflation (need to assess perfusion and muscle viability)
• Tourniquet applied for emergency use only
• Have STSG instruments available (may need immediate grafting)

Anesthesia:

• General anesthesia preferred
• Regional anesthesia (axillary block) acceptable if GA contraindicated
• Ensure adequate muscle relaxation for compartment assessment

Step 1: Assessment for Carpal Tunnel Release

Clinical Assessment:

• Test median nerve: thenar strength (APB - thumb abduction), thumb-index sensation
• Tinel's sign at wrist (tap over carpal tunnel)
• If positive or high suspicion: plan extended volar incision into palm

Step 2: Volar Incision and Skin Exposure

Incision Design (ULNAR approach):

• Start: 2cm distal AND 2cm medial to medial epicondyle (avoids median nerve bifurcation at elbow)
• Course: Straight line along ulnar border of forearm
• At wrist: Oblique across wrist crease toward hypothenar eminence (lateral to Guyon's canal)
• Extension: To mid-palm if carpal tunnel release needed
• Total length: Typically 25-30cm from proximal forearm to palm

Skin Incision:

• Scalpel through skin and subcutaneous tissue
• Preserve basilic vein if possible (may be needed for future access)
• Identify and protect superficial veins and cutaneous nerves
• Avoid crossing wrist crease at 90 degrees (causes contracture scar)

Step 3: Volar Superficial Compartment Release

Fascial Identification:

• Identify antebrachial fascia (glistening white layer)
• Incise longitudinally with scissors or scalpel
• Full-length release from proximal forearm to wrist

Compartment Contents:

• Muscles bulge when fascia released: PT, FCR, palmaris longus (if present), FCU
• Identify median nerve between FDS tendons (~2cm radial to incision)
• Identify ulnar nerve and artery at ulnar border deep to FCU

Nerve Protection:

• Median nerve: trace between FDS tendons, gentle retraction
• Ulnar nerve: runs with ulnar artery under FCU at ulnar border
• Do NOT dissect nerves extensively - just identify and protect

Step 4: Volar Deep Compartment Release

Access to Deep Compartment:

• Deep compartment lies BENEATH flexor digitorum superficialis
• Elevate or gently split FDS muscle belly to access deep space
• Avoid aggressive muscle splitting - may devascularize muscle

Fascial Release:

• Release fascia over FDP muscle belly (ulnar four fingers)
• Release fascia over FPL muscle belly (thumb)
• Release fascia over pronator quadratus distally
• Muscles should bulge - if still tense, extend fascial release

Deep Neurovascular Structures:

• Median nerve: between FDS (superficial) and FDP (deep) layers
• Anterior interosseous nerve: motor branch on interosseous membrane
• AIN innervates: FPL, radial FDP (index/middle), pronator quadratus
• Anterior interosseous artery: runs with AIN

Step 5: Carpal Tunnel Release (If Indicated)

If concurrent CTS suspected:

• Extend volar incision into palm (already designed for this)
• Identify transverse carpal ligament at wrist
• Incise TCL longitudinally under direct vision
• Protect median nerve and recurrent motor branch
• Release complete when median nerve visible and mobile

Verification:

• Median nerve should decompress and become less tense
• Test thumb abduction (APB - recurrent motor branch)

Step 6: Dorsal Incision and Extensor Compartment Release

Dorsal Incision:

• Start: 3cm distal to lateral epicondyle (avoids posterior interosseous nerve)
• Course: Along dorsal forearm between radius and ulna, slightly radial to midline
• End: 3cm proximal to Lister's tubercle (avoids superficial radial nerve)
• Total length: 20-25cm

Fascial Release:

• Incise skin and subcutaneous tissue
• Identify and incise extensor fascia longitudinally
• Release extensor retinaculum distally if needed
• Extensor muscles bulge: EDC, EIP, EDM, EPL, EPB, APL, ECU, ECRL, ECRB

Nerve Protection:

• Superficial radial nerve: becomes subcutaneous 8-10cm above wrist between BR and ECRL
• Identify in distal third, protect during dissection
• Posterior interosseous nerve: stays deep, typically not at risk

Step 7: Mobile Wad Release

From Dorsal Approach:

• Mobile wad located radially between volar and dorsal compartments
• Contains: brachioradialis, ECRL, ECRB
• Release fascia over each muscle
• Muscles should bulge when released

Nerve Consideration:

• Radial nerve becomes superficial radial nerve between BR and ECRL
• Identify approximately 8cm above wrist
• Gentle retraction only - do not dissect extensively

Alternative Access:

• Can be released from volar incision by extending radially
• Dorsal approach generally easier and safer

Step 8: Systematic Verification of Complete Release

Systematic Check:

1. Volar superficial: palpate - should be soft, muscles bulging
2. Volar deep: palpate - should be soft, muscles bulging
3. Dorsal/extensor: palpate - should be soft, muscles bulging
4. Mobile wad: palpate - should be soft, muscles bulging
5. Re-release any residual tight fascia
6. Verify no constricting bands at wrist or elbow

Step 9: Muscle Viability Assessment (Four Cs)

Four Cs Assessment:

1. Color: Pink or red = viable; pale, white, or dark = necrotic
2. Contractility: Stimulate with forceps - viable muscle contracts
3. Consistency: Firm = viable; mushy, soft = necrotic
4. Capacity to bleed: Cut edge bleeds = viable; no bleeding = necrotic

Debridement:

• Clearly necrotic muscle must be debrided
• Prevents rhabdomyolysis, myoglobinuria, renal failure
• Prevents infection
• Marginal muscle can be observed at return to OR

Nerve Function Testing:

• Median: thenar contraction (APB), thumb opposition
• Ulnar: interossei (finger abduction/adduction), hypothenar
• Radial: thumb extension (EPL), wrist extension (ECRL, ECRB)

Step 10: Wound Management - Never Close Primarily

Hemostasis:

• Achieve meticulous hemostasis with bipolar cautery
• Avoid monopolar near nerves
• Ligate large vessels if needed

Irrigation:

• Copious irrigation with normal saline
• Remove any devitalized tissue debris

Open Wound Management:

• NEVER close primarily - risk of recurrent compartment syndrome
• Apply moist dressings: Xeroform or saline-soaked gauze
• Bulky absorbent outer dressing
• Allow for continued swelling

Splinting:

• Position of function critical to prevent contracture
• Wrist: neutral to 20 degrees extension
• MCPs: 60-70 degrees flexion
• IPs: full extension (0 degrees)
• Thumb: abducted (safe position)
• This is "intrinsic-plus" or "safe position"

Step 11: Planning Return to OR

Timing: 48-72 hours

Goals:

• Reassess muscle viability
• Debride any additional necrotic tissue
• Assess for delayed primary closure vs STSG

Closure Options:

1. Delayed primary closure (7-10 days if minimal tension)
2. Vessel loop or shoelace technique for gradual approximation
3. Split-thickness skin graft (10-14 days if cannot close)
4. Negative pressure wound therapy (VAC) to facilitate closure

Complications and Management

Complication Rate Summary

• Volkmann's contracture: 10-40% if fasciotomy delayed beyond 12 hours
• Nerve injury: 5-15% (median most common)
• Need for STSG: 60-70% of cases
• Infection: 5-10%
• Rhabdomyolysis: 20-30% (usually subclinical)
• Chronic stiffness: 30-50% despite appropriate treatment

Recovery and Rehabilitation

Immediate Postoperative (0-48 hours)

Positioning:

• Arm elevated on pillows (reduces swelling)
• Hand above elbow, elbow above heart
• Splint maintains position of function

Wound Care:

• Moist dressings (Xeroform or saline-soaked gauze)
• Bulky absorbent outer dressing
• Changed daily or if strike-through occurs
• Monitor for bleeding, excessive drainage

Monitoring:

• Neurovascular checks every 2 hours initially
• Assess: finger motion, sensation (median, ulnar, radial), perfusion
• Compartment tension (should remain soft)
• Temperature, WBC (infection surveillance)

Medical Management:

• IV antibiotics (cefazolin 2g Q8h or per institutional protocol)
• Adequate analgesia (nerve pain component - consider gabapentin)
• IV hydration (maintain urine output, prevent renal injury)
• Monitor CK levels if rhabdomyolysis suspected
• DVT prophylaxis (SCDs, consider chemoprophylaxis based on bleeding risk)

Return to OR (48-72 hours)

Assessment:

• Reassess muscle viability (four Cs)
• Debride any additional necrotic muscle
• Irrigate copiously
• Check compartment pressures (should be normal)

Closure Options:

1. Too Early for Closure (significant swelling):

   • Repeat dressing change
   • Return again in 48-72 hours
   • Consider VAC therapy

2. Delayed Primary Closure (minimal swelling, edges approximate):

   • Vessel loop or shoelace technique for gradual approximation
   • Tighten gradually over 3-7 days
   • Close when no tension

3. Split-Thickness Skin Graft (cannot close without tension):

   • Usually needed by 10-14 days
   • Harvest 0.012-0.015 inch STSG from thigh
   • Meshed 1:1 or 1.5:1 (allows drainage, accommodates swelling)
   • VAC or bolster dressing for 5-7 days

4. VAC Therapy (bridge to closure):

   • Facilitates granulation tissue formation
   • Reduces edema
   • May allow delayed primary closure in 7-10 days
   • Otherwise prepares for STSG

Hand Therapy (Critical for Outcome)

Phase 1: Immediate (0-2 weeks):

• Passive ROM exercises started immediately after first dressing change
• Gentle passive finger extension/flexion in splint
• Tendon gliding exercises (hook fist, straight fist, full fist)
• Edema control (elevation, compression if tolerated)

Phase 2: Early Active (2-6 weeks):

• Active ROM exercises as pain allows
• Light resistance exercises (therapy putty)
• Scar massage once wounds healed
• Splinting continues between therapy sessions

Phase 3: Strengthening (6-12 weeks):

• Progressive resistance exercises
• Grip strengthening (hand dynamometer)
• Functional activities (writing, buttoning, etc.)
• Desensitization if hypersensitivity present

Phase 4: Functional Return (3-6 months):

• Work conditioning if return to manual labor
• Adaptive equipment if residual weakness
• Ongoing home exercise program

Long-Term Monitoring (Months to Years)

Nerve Recovery:

• Median nerve: Monitor thenar strength, opposition, sensation
• Ulnar nerve: Monitor intrinsic strength, claw hand development
• Radial nerve: Monitor thumb/wrist extension
• Recovery may take 3-12 months
• Consider EMG/NCS at 3 months if no improvement

Functional Assessment:

• Grip strength (compared to contralateral)
• ROM measurements (goniometer)
• Functional tasks (Jebsen-Taylor Hand Function Test)
• Return to work/activities

Complications:

• Volkmann's contracture may require late reconstruction
• Chronic pain may need pain management referral
• Tendon adhesions may require tenolysis

Expected Outcomes

Early Fasciotomy (less than 6 hours):

• 80-90% good to excellent function
• Most nerve function recovers
• Minimal contracture

Delayed Fasciotomy (6-12 hours):

• 50-70% good to excellent function
• Variable nerve recovery
• Some contracture common

Late Fasciotomy (over 12 hours):

• 20-40% good to excellent function
• Permanent nerve damage common
• Volkmann's contracture likely