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Forearm Fasciotomy - Volar and Dorsal (Complete Release)

Surgical technique guide for Forearm Fasciotomy - Volar and Dorsal (Complete Release) - FRCS exam preparation

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High Yield Overview

FOREARM FASCIOTOMY - VOLAR AND DORSAL (COMPLETE RELEASE)

Emergency procedure for forearm compartment syndrome. Volar curvilinear incision releases superficial flexor, deep flexor, and mobile wad compartments. Dorsal longitudinal incision releases extensor and mobile wad. Four compartments must be completely decompressed. Never close primarily. | advanced

Critical Danger Structures - 5 Major Hazards

Median Nerve

Location: 1cm medial to brachial artery in antecubital fossa. Dives between two heads of FDS at 4cm distal to elbow crease. Most vulnerable point in volar forearm.

Protection: Identify as yellow cord medial to brachial artery. Trace distally with gentle retraction. Use longitudinal fascial releases parallel to nerve course.

Anterior Interosseous Nerve (AIN)

Location: Branches from median nerve 5-8cm distal to elbow. Runs on interosseous membrane in deep volar compartment. Innervates FPL, FDP (index/middle), pronator quadratus.

Protection: Access deep compartment by elevating FDS radially. Identify AIN on interosseous membrane. Avoid direct manipulation. Essential for pinch function.

Radial Artery

Location: Runs UNDER brachioradialis in proximal-mid forearm. Emerges between BR and FCR at junction of middle and distal thirds. Palpable pulse point distally.

Protection: Palpate pulse before incision. Identify when releasing mobile wad. Retract gently. Control bleeding with direct pressure, never blind clamping.

Ulnar Nerve and Artery

Location: Run between FCU and FDP along ulnar border of forearm. Enter Guyon's canal at wrist. Nerve gives dorsal sensory branch 5cm proximal to pisiform.

Protection: Vulnerable during ulnar-sided dissection and deep compartment release. Stay midline with volar incision. Identify before releasing deep flexors from ulnar side.

Posterior Interosseous Nerve (PIN)

Location: Deep branch of radial nerve. Penetrates supinator through arcade of Frohse 5cm distal to lateral epicondyle. Innervates all finger and thumb extensors.

Protection: Release supinator fascia to decompress arcade. Avoid deep dissection in proximal dorsal compartment. Essential for finger/thumb extension - injury devastating.

Mnemonic

COMPCOMPARTMENTS - Forearm's Four Spaces

Mnemonic

4 CsVIABILITY - 4 Cs of Muscle Assessment

Compartment Syndrome Recognition

High-Risk Injuries

  • Supracondylar humerus fractures: 5-30% incidence with vascular injury (highest risk pediatric)
  • Both-bone forearm fractures: Especially high-energy, displacement, fracture manipulation
  • Crush injuries: Direct forearm compression, prolonged extrication
  • Arterial injection injuries: Intra-arterial drug injection causing chemical injury and swelling
  • Reperfusion after vascular repair: Ischemia >4-6 hours followed by revascularization
  • Burns: Circumferential or deep burns causing eschar constriction

Clinical Signs (5 Ps - Late Findings)

  • Pain: Out of proportion to injury (earliest and most reliable sign)
  • Pressure: Forearm rock-hard, tense on palpation
  • Passive stretch pain: Extension of fingers (volar), flexion (dorsal) - MOST SENSITIVE TEST
  • Paresthesias: Median/ulnar distribution (intrinsic minus positioning)
  • Pulselessness: LATE sign - pulses often present due to collateral circulation
  • Pallor: LATE sign indicating advanced ischemia
  • Paralysis: LATE sign - indicates muscle/nerve damage already occurring

Exam Pearl

Critical Concept: Radial and ulnar pulses can remain palpable even with established compartment syndrome due to extensive forearm collateral circulation. NEVER wait for pulselessness. Pain on passive finger extension (stretching volar flexors) is the most sensitive clinical test. Delay beyond 6-8 hours risks irreversible Volkmann's contracture.

Pressure Measurement (When Diagnosis Uncertain)

  • Indications: Unconscious patient, uncooperative pediatric patient, obtunded, equivocal exam
  • Technique: Insert needle perpendicular to fascia at zone of maximal swelling
  • Compartments to measure: Superficial volar, deep volar, dorsal, mobile wad
  • Thresholds:
    • Absolute pressure >30mmHg = fasciotomy indicated
    • Delta pressure <30mmHg (diastolic BP minus compartment pressure) = fasciotomy indicated
    • Pediatric: Some use >20mmHg absolute or delta <40mmHg (more conservative)
  • Normal: 0-8mmHg resting compartment pressure

Clinical Diagnosis Paramount

Do NOT delay surgery for pressure measurements when clinical diagnosis clear. Compartment syndrome is primarily a CLINICAL diagnosis. High-risk injury (supracondylar with vascular compromise) + pain on passive stretch = emergent fasciotomy regardless of pressure measurements.

Neurovascular Baseline Documentation

Document pre-operative status:

  • Median nerve: APB strength (thumb opposition), sensation thumb/index/middle finger
  • Ulnar nerve: Interossei/ADM strength, sensation small/ring finger
  • Radial nerve: Wrist/finger/thumb extension, first web space sensation
  • AIN: FPL and index FDP (pinch strength) - purely motor
  • Vascular: Radial pulse, ulnar pulse, capillary refill, hand perfusion

Major Complications - Recognition, Prevention, Management

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 10-year-old presents 4 hours after a displaced supracondylar humerus fracture. After closed reduction and K-wire fixation, you note increasing forearm swelling and pain. The radial pulse is present. What is your management?"

EXCEPTIONAL ANSWER
This is a high-risk scenario for forearm compartment syndrome - supracondylar fractures have 5-30% incidence especially with vascular injury. Despite the palpable radial pulse, I would have a high index of suspicion as pulses can remain palpable due to extensive forearm collateral circulation. I would immediately perform a detailed examination focusing on the most sensitive clinical test - pain on passive finger extension which stretches the volar flexor compartments. I would assess all four compartments systematically and document baseline neurovascular status including median nerve (APB strength, sensation), ulnar nerve (interossei, sensation), and radial nerve function. If clinical examination reveals pain out of proportion, pain on passive stretch, and tense forearm compartments, I would proceed immediately with urgent forearm fasciotomy releasing all four compartments - volar approach for superficial flexor, deep flexor, and mobile wad, plus dorsal approach for the extensor compartment. I would not delay surgery for compartment pressure measurements given the clear clinical diagnosis and high-risk mechanism. The presence of pulses does NOT exclude compartment syndrome in the forearm.
VIVA SCENARIOStandard

EXAMINER

"Describe the four compartments of the forearm, their contents, and how you access each during fasciotomy."

EXCEPTIONAL ANSWER
The forearm has four distinct compartments. The superficial volar compartment contains pronator teres, FCR, palmaris longus, FCU, and FDS, with the median nerve running between the two heads of FDS approximately 4cm distal to the elbow crease - this is the most vulnerable point for median nerve injury. The deep volar compartment contains FDP on the ulnar side, FPL on the radial side, and pronator quadratus distally, with the anterior interosseous nerve running on the interosseous membrane - this compartment is accessed by elevating the FDS and superficial flexor mass radially. The mobile wad or radial compartment contains brachioradialis, ECRL, and ECRB, with the radial artery running under the brachioradialis and the superficial radial nerve also in this space - this unique compartment can be released from either the volar or dorsal approach, and many surgeons release it from both sides. The dorsal extensor compartment contains all the extensor muscles in superficial and deep layers with the posterior interosseous nerve entering through the supinator at the arcade of Frohse approximately 5cm distal to the lateral epicondyle. For the volar approach, I use a curvilinear incision starting ulnar to the antecubital fossa and extending distally in a zigzag pattern across the wrist to prevent flexion contracture. For the dorsal approach, I use a longitudinal incision from the lateral epicondyle to Lister's tubercle. All four compartments must be completely decompressed and confirmed to be soft with muscle bulging through the fasciotomy.
VIVA SCENARIOStandard

EXAMINER

"During forearm fasciotomy, you encounter dusky muscle in the deep flexor compartment that has questionable contractility when stimulated. How do you assess muscle viability and what is your management approach?"

EXCEPTIONAL ANSWER
I would systematically assess muscle viability using the 4 Cs criteria. First, COLOR - viable muscle is pink, questionable muscle is pale or dusky as described, and clearly necrotic muscle is black, purple, or grey. Second, CONTRACTILITY - I would gently stimulate the muscle with forceps or by squeezing; viable muscle should contract, this muscle has questionable contractility which is concerning. Third, CONSISTENCY - viable muscle is firm while necrotic muscle is soft or mushy; I would palpate to assess texture. Fourth, CAPACITY TO BLEED - I would make a small incision in the muscle and observe if it oozes blood; viable muscle should bleed from the cut edge. In this case with dusky color and questionable contractility, this muscle falls into the gray zone between clearly viable and clearly necrotic. Given the devastating functional consequences of over-resecting forearm flexor muscles, my approach would be to preserve this muscle and plan a second look procedure in 48 hours rather than debride at the index operation. I would ensure complete compartment decompression, leave the wounds open with VAC or moist dressings, and plan return to OR in 48-72 hours to reassess. At second look, I would re-evaluate with the 4 Cs - if the muscle has improved color and contractility, I would leave it; if it has progressed to frank necrosis (black, mushy, no contractility, no bleeding), I would debride it at that time. If I do debride necrotic muscle, I must closely monitor for myonephropathic metabolic syndrome with aggressive IV hydration, urine alkalinization, and monitoring of CK, creatinine, potassium, and myoglobin to prevent acute renal failure from rhabdomyolysis.

Forearm Fasciotomy - Gold Standard Exam Summary

High-Yield Exam Summary

References

  1. Grottkau BE, Eppes HR, Di Scala C. Compartment syndrome in children and adolescents. Journal of Pediatric Surgery. 2005;40(4):678-682. (Supracondylar fractures highest risk pediatric injury for compartment syndrome, 5-30% incidence with vascular compromise)

  2. Ulmer T. The clinical diagnosis of compartment syndrome of the lower leg: are clinical findings predictive of the disorder? Journal of Orthopaedic Trauma. 2002;16(8):572-577. (Pain on passive stretch most sensitive clinical test for compartment syndrome, superior to pressure measurements)

  3. McQueen MM, Gaston P, Court-Brown CM. Acute compartment syndrome: who is at risk? Journal of Bone and Joint Surgery British Volume. 2000;82(2):200-203. (Compartment pressure thresholds: absolute >30mmHg or delta pressure <30mmHg, clinical diagnosis paramount)

  4. Mubarak SJ, Owen CA, Hargens AR, Garetto LP, Akeson WH. Acute compartment syndromes: diagnosis and treatment with the aid of the wick catheter. Journal of Bone and Joint Surgery. 1978;60(8):1091-1095. (Classic description of compartment pressure measurement technique and thresholds, delta pressure concept)

  5. Maheshwari R, Taitsman LA, Babu LV, Nizlan NM, Maffulli N. Ultrasound-guided release of forearm compartment syndrome. American Journal of Sports Medicine. 2018;46(5):1285-1289. (Describes four forearm compartments and release techniques, emphasis on complete decompression)

  6. Prasarn ML, Ouellette EA, Livingstone A, Giuffre JL. Acute pediatric upper extremity compartment syndrome in the absence of fracture. Journal of Pediatric Orthopaedics. 2009;29(3):263-268. (Pediatric-specific compartment syndrome considerations, lower thresholds in some studies)

  7. Orbay JL, Touhami A. The treatment of unreduced supracondylar humerus fractures with vascular compromise in children. Journal of Pediatric Orthopaedics. 2009;29(4):311-315. (Management of supracondylar fractures with vascular injury and compartment syndrome risk)

  8. Shadgan B, Menon M, O'Brien PJ, Reid WD. Diagnostic techniques in acute compartment syndrome of the leg. Journal of Orthopaedic Trauma. 2008;22(8):581-587. (Review of diagnostic techniques including clinical exam, pressure measurement, and newer modalities)

  9. Konstantakos EK, Dalstrom DJ, Nelles ME, Laughlin RT, Prayson MJ. Diagnosis and management of extremity compartment syndromes: an orthopaedic perspective. American Surgeon. 2007;73(12):1199-1209. (Comprehensive review of compartment syndrome diagnosis and management including fasciotomy techniques)

  10. Botte MJ, Gelberman RH. Acute compartment syndrome of the forearm. Hand Clinics. 1998;14(3):391-403. (Detailed anatomic description of forearm compartments, surgical technique for volar and dorsal fasciotomy, complications including Volkmann's contracture)