Perioperative & Surgical Care

Acute compartment syndrome: recognition and fasciotomy

Clinical Overview and When to Suspect Acute Compartment Syndrome

— Compartment pressure rises → venous outflow obstruction → capillary leak → further pressure rise (vicious cycle)

— Perfusion fails when delta pressure (ΔP = diastolic BP − compartment pressure) ≤ 30 mmHg

— Irreversible muscle injury begins at ~4–6 hours of ischemia; nerve dysfunction begins within 30 min–2 h

— Long-bone fractures, especially tibial diaphyseal fracture (highest incidence, ~1–10%) and distal radius fractures in children/young adults

— Crush injury, prolonged limb compression (obtunded patient, "found down," lithotomy positioning)

— Reperfusion after vascular repair or thrombectomy

— Tight casts, circumferential burns/eschar, anticoagulated patient with spontaneous hematoma

— IV infiltration/extravasation, snakebite, electrical injury, vigorous exercise (exertional, often chronic)

— Young males <35 with high-energy trauma (highest risk group on boards)

— Obtunded ICU/trauma patient who cannot report pain — lower your threshold to measure pressures

Board pearl: ACS is a clinical diagnosis in the awake, examinable patient — do not delay fasciotomy waiting for pressure measurements if exam is convincing. Pressure monitoring is reserved for obtunded, intubated, or equivocal patients. A normal pulse and pink skin do not rule out ACS; arterial inflow is usually preserved until very late.

Definition: Acute compartment syndrome (ACS) is a surgical emergency in which tissue pressure within a closed osteofascial compartment exceeds perfusion pressure, producing ischemia, myonecrosis, and ultimately nerve death if not decompressed.

Pathophysiology snapshot:

Classic settings to suspect:

Demographics that raise suspicion:

Compartments commonly involved: leg (4 compartments — anterior most common), forearm (volar/dorsal/mobile wad), thigh, hand, foot, gluteal, abdominal.

Presentation Patterns and Key History

— Pain out of proportion to injury and pain with passive stretch of the involved compartment are the earliest and most sensitive findings

— Paresthesias (next earliest — small sensory fibers fail first)

— Pallor, paralysis, pulselessness — late and ominous; their absence does NOT exclude ACS

— Tibial shaft fracture in a young male after MVC/sports → leg ACS, anterior compartment first

— Supracondylar humerus fracture in a child → Volkmann ischemic contracture risk (forearm)

— Reperfusion after >4–6 h of acute limb ischemia or vascular bypass → prophylactic fasciotomy often indicated

— "Found down" after overdose, stroke, or alcohol intoxication → gluteal, thigh, or leg ACS from prolonged pressure + rhabdomyolysis

— Tight circumferential cast or splint applied in ED → ask when applied, escalating pain despite analgesia

— Anticoagulated patient (warfarin, DOAC, heparin) with minor trauma → spontaneous compartment hematoma, classically thigh or forearm

— Snakebite (crotalid), high-pressure injection injury to hand, electrical burns

— Crescendo pain unrelieved by opioids is a red flag — document escalating analgesic requirement

— Loss of pain in a previously painful limb may mean nerve death, not improvement

— Increasing Analgesia requirement, Anxiety, Agitation

Step 3 management: When called about a postop or post-fracture patient with rising opioid demand and tense extremity, go see the patient, remove circumferential dressings/cast to skin, and call ortho — do not simply increase the PCA. Failure to evaluate in person is a recurring malpractice and exam theme.

The "5 P's" — but reframe for Step 3:

History clues by mechanism:

Pain pattern specifics:

Pediatric "3 A's" (more reliable than 5 P's in kids who can't localize):

Physical Exam Findings and Hemodynamic Assessment

— Tense, "wood-hard" compartment is the single most specific exam finding

— Shiny, taut skin; swelling out of proportion; blistering in late disease

— Compare side-to-side; mark skin to track progression

— Firmness of each compartment individually (leg has 4 — anterior, lateral, superficial posterior, deep posterior; deep posterior is the most commonly missed)

— Tenderness over the muscle belly, not just the fracture site

— Anterior leg compartment → passive plantarflexion of toes/ankle reproduces pain (tibialis anterior, EHL)

— Deep posterior leg → passive toe extension and ankle dorsiflexion

— Volar forearm → passive finger/wrist extension

— Anterior leg: deep peroneal nerve — first web space sensation, dorsiflexion weakness, foot drop

— Lateral leg: superficial peroneal — dorsolateral foot sensation, eversion

— Deep posterior: tibial nerve — plantar sensation, toe flexion

— Volar forearm: median nerve — index pulp sensation

— Pulses are typically preserved because compartment pressures rarely exceed systolic BP

— Doppler signals present until very late — a triphasic Doppler does not rule out ACS

— Capillary refill is unreliable

— Hypotension lowers the threshold for ischemia — a shocky trauma patient with DBP 50 develops ACS at lower absolute compartment pressures; resuscitate aggressively while planning decompression

Key distinction: Acute limb ischemia (cold, pulseless, pale from the start, embolic source) vs ACS (warm or normal-temp limb, palpable pulse, tense compartment, pain with passive stretch) — both can coexist after reperfusion, where prophylactic fasciotomy is standard.

Inspection:

Palpation:

Provocative maneuver — passive stretch test:

Neurologic exam (compartment-specific):

Vascular exam:

Hemodynamic context:

Diagnostic Workup — Initial Labs, Imaging, and Compartment Pressure Measurement

— CK — elevated in rhabdomyolysis; trend q6–8h; values >5,000 U/L mark significant muscle injury, >15,000–20,000 predict AKI risk

— BMP — hyperkalemia, hyperphosphatemia, hypocalcemia, AKI from myoglobinuric pigment nephropathy

— Urinalysis — heme-positive dipstick without RBCs = myoglobinuria

— Lactate, ABG/VBG — metabolic acidosis from anaerobic muscle metabolism

— CBC, coags, type & screen (preop), LFTs

— Plain radiographs for associated fracture

— Imaging is otherwise of limited diagnostic value for ACS itself; do NOT delay fasciotomy for CT/MRI

— Vascular imaging (CTA) only if concurrent arterial injury suspected

— Obtunded/intubated/sedated patient

— Unreliable exam (pediatric, intoxicated, regional anesthesia in place, polytrauma with distracting injury)

— Equivocal exam where clinical suspicion is moderate

— Stryker handheld manometer or arterial line transducer via slit catheter or side-port needle

— Measure within 5 cm of the fracture (highest pressures); measure all four leg compartments — anterior, lateral, superficial posterior, deep posterior (often missed and most likely to be elevated)

— Zero at the level of the compartment

— ΔP = DBP − compartment pressure ≤ 30 mmHg → fasciotomy (current standard; more sensitive than absolute number)

— Absolute pressure >30 mmHg is concerning but ΔP is preferred because it accounts for perfusion

Board pearl: The most commonly tested wrong answer is "wait for MRI" or "serial exams over 24 h." In a patient with ΔP ≤ 30 or convincing exam, the next step is emergent fasciotomy, not more imaging.

Diagnosis is primarily clinical — labs and imaging support, do not replace, exam.

Initial labs (obtain but do not delay decompression):

Imaging:

Compartment pressure measurement — indications:

Technique:

Interpretation thresholds:

Diagnostic Workup — Continuous Monitoring and Adjuncts

— Slit catheter or side-port needle connected to arterial line transducer can be left in place for trending in obtunded trauma patients

— Useful in tibial plateau/shaft fractures awaiting OR, especially with regional anesthesia or epidural that may mask pain

— Trend ΔP every 1–2 h; sustained ΔP ≤ 30 mmHg over 2 h → fasciotomy

— Emerging noninvasive adjunct measuring tissue oxygenation in superficial compartments

— Not yet standard of care; do not pick on exam unless explicitly described as adjunctive

— Trend CK q6–8h post-decompression — a falling CK suggests adequate decompression; rising CK after fasciotomy raises concern for missed compartment or ongoing necrosis requiring re-exploration

— Myoglobin clears faster than CK and is less useful for trending

— Hourly urine output via Foley catheter, target >1–2 mL/kg/h with clear (not tea-colored) urine

— BMP q6h initially for K⁺, Ca²⁺, Cr

— ECG monitoring for hyperkalemia (peaked T waves, widened QRS)

— Intraoperative findings of bulging, dusky, non-contractile muscle on fascial release confirm diagnosis

— Viable muscle: pink, contracts to electrocautery stimulation, bleeds when cut ("4 C's" — color, contractility, consistency, capillary bleeding)

CCS pearl: In a CCS case of suspected ACS, order in sequence: vitals → focused limb exam → remove cast/circumferential dressing → CK, BMP, UA, type & screen → orthopedic surgery consult STAT → IV fluids → analgesia → keep limb at heart level (not elevated, which reduces arterial inflow). Advance clock minimally — every hour of delay costs muscle.

Continuous compartment pressure monitoring:

Near-infrared spectroscopy (NIRS):

Serum biomarkers for muscle injury:

Renal monitoring for rhabdomyolysis:

Operative confirmation:

Risk Stratification and First-Line Management Logic

— Convincing clinical exam (awake patient): → fasciotomy, no pressure needed

— Equivocal exam or unreliable patient: → measure compartment pressures → ΔP ≤ 30 mmHg → fasciotomy

— Impending ACS (rising pressures, escalating analgesia, but ΔP still >30): → admit, frequent reassessment q1h, remove all circumferential dressings, normalize BP, prepare OR

— Reversible ischemia: <4 h

— Variable injury: 4–8 h

— Irreversible necrosis: >8 h — fasciotomy beyond 8–12 h in a missed case may increase infection/amputation risk because dead muscle is exposed; some surgeons defer to delayed debridement

— Remove cast, splints, and circumferential dressings down to skin — a bivalved cast still compresses; cut and spread

— Position limb at the level of the heart — elevation reduces arterial driving pressure and worsens ischemia

— Treat hypotension to restore ΔP — IV crystalloid, blood as needed

— Correct hypoxia, supplemental O₂

— Avoid vasopressors that may worsen distal perfusion if alternatives exist

— Adequate analgesia (IV opioids) — but do not rely on pain control as therapy

— Ice packs (vasoconstriction)

— Prolonged tourniquet

— Regional anesthesia in at-risk limbs without surgical plan (may mask ACS)

Step 3 management: First action when ACS is suspected in a casted limb is bivalve and spread the cast and underlying padding to skin — this alone can drop compartment pressure 50–85%. Then reassess in 30 minutes while mobilizing the OR team.

Decision algorithm:

Time is muscle:

Pre-fasciotomy bedside maneuvers (do all immediately):

Avoid:

Pharmacotherapy and Supportive Medical Management

— IV opioids (morphine, hydromorphone, fentanyl) — titrate but document escalating requirements as evidence of evolving ACS

— Avoid peripheral nerve blocks and epidurals in at-risk limbs preoperatively — they mask the cardinal symptom (pain)

— Acetaminophen IV as adjunct; avoid NSAIDs preoperatively (bleeding risk, AKI in rhabdo)

— Aggressive IV crystalloid — isotonic saline or LR at 200–500 mL/h, titrate to UOP 1–2 mL/kg/h (some use up to 300–500 mL/h initially in severe cases)

— Continue until CK trends down and urine clears

— Sodium bicarbonate to alkalinize urine (target urine pH >6.5) — controversial; reserve for severe rhabdo (CK >5,000) without alkalemia/hypocalcemia

— Mannitol — not routinely recommended; risk of AKI and volume issues

— Avoid LR if severe hyperkalemia (contains 4 mEq/L K⁺) — switch to NS

— Calcium gluconate (membrane stabilization), insulin + D50, albuterol, sodium bicarbonate, kayexalate/patiromer, dialysis for refractory cases or oliguric AKI

— Preop cefazolin for open fractures or contaminated wounds; add gentamicin for grossly contaminated (Gustilo III)

— Tetanus prophylaxis for open injuries

— Hold pharmacologic prophylaxis preoperatively; resume 24 h post-fasciotomy if hemostasis secure; use mechanical compression on uninjured limb meanwhile

— Warfarin → vitamin K + 4-factor PCC; DOACs → andexanet alfa (apixaban/rivaroxaban) or idarucizumab (dabigatran); heparin → protamine — needed urgently if anticoagulant-associated hematoma

Board pearl: Hypocalcemia in rhabdo is early and asymptomatic — do NOT replace calcium unless symptomatic (tetany, arrhythmia) or severely low, because calcium precipitates with phosphate in damaged muscle and worsens injury; rebound hypercalcemia occurs during recovery.

There is no pharmacologic treatment for ACS itself — fasciotomy is definitive. Drugs target complications and perioperative needs.

Analgesia:

Rhabdomyolysis management:

Hyperkalemia treatment:

Antibiotics:

VTE prophylaxis:

Anticoagulation reversal:

Fasciotomy — Operative Technique and Decompression

— Lateral incision over fibula: releases anterior (avoid superficial peroneal nerve at distal third) and lateral compartments

— Medial incision 2 cm posterior to posteromedial tibial border: releases superficial posterior (gastroc/soleus) and deep posterior (tibialis posterior, FDL, FHL) — deep posterior most commonly missed

— Single-incision lateral parafibular technique is alternative

— Volar Henry approach — curvilinear incision releases volar superficial and deep compartments, carpal tunnel release included

— Dorsal incision if dorsal compartment still tight after volar release

— Skin and fascia released along the full length — short incisions fail; "skin is a compartment"

— Debride frankly necrotic muscle (4 C's assessment)

— Leave wounds open with negative-pressure wound therapy or saline-moistened gauze

— Return to OR in 48–72 h for re-look, additional debridement, and staged closure

— Delayed primary closure vs split-thickness skin graft depending on swelling

Step 3 management: Post-fasciotomy orders — elevate limb now that decompression is done (reduces edema), serial neurovascular checks q1–2h, CK trending, monitor for ongoing rhabdo, plan return to OR within 48–72 h. Document compartment release of all four leg compartments in the operative note — missed deep posterior is a classic malpractice/exam pitfall.

Procedure of choice: emergent open fasciotomy with release of all involved compartments. Time goal: <6 h from symptom onset.

Leg — two-incision four-compartment fasciotomy (most tested):

Forearm:

Thigh: Lateral incision releases anterior and posterior compartments; medial incision for adductor compartment if involved

Hand: Dorsal incisions over 2nd and 4th metacarpals (interossei), thenar/hypothenar/carpal tunnel as needed

Foot: Two dorsal + medial incisions for 9 compartments — controversial; many defer

Abdominal compartment syndrome: Decompressive laparotomy with temporary abdominal closure (vacuum dressing) for bladder pressure >20 mmHg with new organ dysfunction

Operative principles:

Special Populations — Elderly and Renal/Hepatic Impairment

— Lower incidence of ACS overall because atrophic muscle generates less pressure, but higher mortality when it occurs due to comorbidity

— Atypical presentation: confusion, less robust pain response, comorbid neuropathy (diabetic) masks paresthesias

— Polypharmacy: anticoagulants → spontaneous compartment hematomas (especially thigh after groundlevel fall)

— Lower DBP baselines + antihypertensives → ΔP threshold reached at lower compartment pressures; hold antihypertensives preoperatively, target MAP ≥65 (DBP ≥60 if possible)

— Postop delirium prophylaxis (orientation, sleep hygiene, avoid benzodiazepines/anticholinergics)

— Pigment nephropathy is the dominant renal complication; CK >5,000 raises risk, >15,000–20,000 high risk

— Fluid resuscitation must balance volume (avoid pulmonary edema in CHF/CKD) — monitor with bedside US, JVP, lactate

— Indications for RRT: refractory hyperkalemia, severe metabolic acidosis (pH <7.1), volume overload, uremic complications, oliguric AKI not responsive to fluids

— Drug dose adjustments: LMWH → unfractionated heparin if CrCl <30; adjust opioids (avoid morphine metabolites in renal failure — prefer hydromorphone or fentanyl); avoid NSAIDs and IV contrast

— Coagulopathy increases hematoma risk; correct INR with PCC + vitamin K preoperatively if >1.5 and bleeding

— Reduced hepatic synthesis → hypoalbuminemia → impaired wound healing post-fasciotomy

— Drug adjustments: reduce opioid doses, avoid acetaminophen >2 g/day in cirrhosis, careful with cefazolin (generally safe)

Board pearl: Elderly anticoagulated patient on warfarin with spontaneous thigh pain and swelling after minor fall = spontaneous quadriceps compartment syndrome from hematoma. Reverse anticoagulation urgently and decompress — do not wait for repeat INR or imaging if exam is convincing.

Elderly patients:

Renal impairment / AKI from rhabdomyolysis:

Hepatic impairment:

Diabetic patients: Baseline neuropathy obscures sensory exam — rely on pain with passive stretch and compartment firmness; tighter glucose control postoperatively to support wound healing.

Special Populations — Pediatrics, Pregnancy, and Other Subgroups

— Most common settings: supracondylar humerus fracture (forearm ACS → Volkmann contracture), tibial fractures, both-bone forearm fractures, IV infiltration in infants

— Children cannot reliably report pain — rely on the 3 A's: Anxiety, Agitation, escalating Analgesia requirement (more sensitive than 5 P's)

— Lower compartment pressure thresholds may apply; ΔP ≤ 30 still useful but exam trumps numbers

— Volkmann ischemic contracture: late sequela of missed forearm ACS — clawed hand from flexor muscle fibrosis; preventable only by timely fasciotomy

— Neonatal ACS often from IV extravasation; presents with swollen, dusky limb — emergency

— Rare; consider with trauma, eclamptic seizure–related rhabdomyolysis, or postpartum lithotomy positioning (gluteal/leg ACS)

— Imaging concerns minimal because ACS is clinical; avoid unnecessary CT

— Anesthesia: epidural can mask leg ACS in postpartum patients — high index of suspicion if persistent leg pain after delivery

— Cannot examine reliably — continuous compartment pressure monitoring is standard for tibial fractures awaiting fixation

— Sedation, paralytics, head injury all mask classic symptoms

— Usually chronic in young runners/military recruits, bilateral, reproducible at predictable mileage, resolves with rest

— Diagnosed by post-exercise pressure measurement

— Elective fasciotomy, not an emergency

— Crotalid envenomation rarely causes true ACS — most swelling is subcutaneous; measure pressures before fasciotomy and treat with antivenom (CroFab) first

— High-pressure paint/grease injection to hand → urgent surgical debridement regardless of pressures

Key distinction: Acute (emergency, fasciotomy now) vs chronic exertional (elective workup with post-exercise pressures, fasciotomy is scheduled) compartment syndrome — distinct management; do not conflate on exam.

Pediatric ACS:

Pregnancy:

Obtunded / ICU / polytrauma patients:

Exertional compartment syndrome (different entity, contrast):

Snakebite / high-pressure injection:

Complications and Adverse Outcomes

— Muscle necrosis → permanent weakness, fibrosis, contracture (Volkmann in forearm, equinus contracture in leg)

— Permanent nerve injury — foot drop (deep peroneal), sensory loss, neuropathic pain

— Rhabdomyolysis → AKI requiring RRT; mortality climbs with combined renal + cardiac dysfunction

— Hyperkalemia-induced arrhythmia / cardiac arrest — especially after reperfusion ("reperfusion syndrome")

— Limb loss / amputation — risk rises sharply after 8–12 h of ischemia or in delayed presentations

— Death from multiorgan failure, sepsis, or hyperkalemic arrest

— Wound infection, often polymicrobial; necrotizing soft tissue infection in immunocompromised

— Chronic open wound, delayed closure, need for split-thickness skin grafting → cosmetic and functional deficits

— Iatrogenic nerve injury: superficial peroneal nerve in lateral leg fasciotomy, saphenous nerve/vein in medial leg incision

— Persistent muscle herniation through fascial defects

— Chronic venous insufficiency, lymphedema

— Phantom pain, chronic regional pain syndrome

— Opening a necrotic compartment exposes dead muscle → sepsis risk; some advocate delayed debridement only rather than emergent fasciotomy in unequivocally late presentations — individualized decision

— Sudden hyperkalemia, lactic acidosis, hypocalcemia, hypotension; pretreat with bicarbonate, calcium, manage as for crush injury

Board pearl: The single most litigated complication of ACS is failure to diagnose — typical scenario is a tibial fracture patient whose nurse documents escalating pain calls overnight, intern increases the PCA without bedside evaluation, and the patient develops Volkmann-type contracture. Always see the patient in person and document neurovascular exam.

From the syndrome itself (missed or delayed decompression):

From the fasciotomy procedure:

Late or missed fasciotomy (>8–12 h with established necrosis):

Reperfusion syndrome (after vascular repair or late fasciotomy):

When to Escalate Care — ICU, Consults, and Inpatient Triage

— Orthopedic surgery STAT for extremity ACS — they perform the fasciotomy

— General/trauma surgery for abdominal compartment syndrome or polytrauma context

— Vascular surgery if concurrent arterial injury or reperfusion fasciotomy

— Plastic surgery for forearm/hand cases or delayed closure/grafting planning

— Nephrology if AKI requiring RRT or refractory electrolyte disturbance

— Anesthesia for emergent OR availability

— CK >5,000 with AKI or rising trend

— Hyperkalemia requiring repeated treatment

— Hemodynamic instability or massive transfusion

— Polytrauma, intubation, severe metabolic acidosis

— Reperfusion injury after vascular repair

— Abdominal compartment syndrome (always ICU)

— Isolated extremity fasciotomy without significant rhabdo, hemodynamically stable, normal renal function — q2–4h neurovascular checks acceptable on a monitored ortho ward

— Community hospital without 24/7 orthopedic coverage → expedite transfer to a Level I/II trauma center; do not delay fasciotomy waiting for transfer if local surgeon can decompress

— Pediatric cases without pediatric orthopedics → transfer after initial stabilization and (if needed) fasciotomy by general orthopedist

— Time of injury, time of symptom onset, time of fasciotomy, compartments released, debridement extent, plan for re-look

— CK trend and last K⁺

— Anticoagulation status and last dose

CCS pearl: On a CCS case, if you select "transfer to tertiary center" before fasciotomy in a clear ACS, you may lose points for delayed definitive care. Decompress first (or have ortho on the way to OR) then transfer for definitive fracture care if needed.

Immediate consults:

ICU admission criteria post-fasciotomy:

Step-down or ortho floor:

Transfer indications:

Communication and handoff:

Key Differentials — Same-Category (Musculoskeletal/Vascular Limb) Causes

— Sudden onset 6 P's: Pain, Pallor, Pulselessness, Paresthesia, Paralysis, Poikilothermia (cold limb)

— Limb is cold and pulseless from the start, compartments soft initially

— Source: embolic (AF, post-MI mural thrombus), thrombotic (peripheral arterial disease)

— Workup: CTA; treatment: heparin, embolectomy/thrombectomy, bypass

— Can cause ACS via reperfusion → prophylactic fasciotomy if ischemia >4–6 h

— Unilateral leg swelling, calf tenderness, but compartment is soft, no pain with passive stretch

— Duplex ultrasound diagnostic; anticoagulate

— Phlegmasia cerulea dolens — massive iliofemoral DVT with venous outflow obstruction can mimic and cause ACS

— Warmth, erythema, fever, leukocytosis; necrotizing fasciitis has pain out of proportion (like ACS) plus crepitus, bullae, gas on imaging, septic appearance

— LRINEC score, surgical exploration; do not confuse with ACS — both need emergent OR but procedures differ

— Pain localized to fracture site, relieved with immobilization and standard analgesia; compartment soft

— Tender but compressible; pressures normal

— Chronic, exertional, no acute tense compartment

— Exercise-induced, resolves with rest, bilateral — elective fasciotomy

Key distinction: Acute limb ischemia → cold, pulseless, soft compartment, embolic history. ACS → warm or normal, pulse usually present, tense compartment, pain with passive stretch. Both can coexist after revascularization — recognize and decompress.

Acute limb ischemia (arterial occlusion):

Deep vein thrombosis (DVT):

Cellulitis / necrotizing soft tissue infection:

Fracture-related pain (uncomplicated):

Muscle strain / contusion / hematoma without ACS:

Stress fracture / shin splints / medial tibial stress syndrome:

Chronic exertional compartment syndrome:

Key Differentials — Other-Category Causes

— Crush, statin/fibrate toxicity, prolonged immobility, seizures, hyperthermia, cocaine — elevated CK, dark urine, but compartments soft and compressible

— IV fluids alone; no fasciotomy

— Distinguish: ACS has the tense compartment; rhabdo alone does not

— Warm, erythematous, sharply demarcated, fever, responds to antibiotics; compartment soft

— Single joint, severe pain on passive ROM of the joint (not stretch of muscle), fever, joint effusion; arthrocentesis with WBC >50,000 PMN-predominant

— Tropical or immunocompromised host, Staph aureus muscle abscess; MRI diagnostic; drainage + antibiotics

— Swelling, ecchymosis, coagulopathy; measure pressures before fasciotomy — most cases respond to antivenom (CroFab) without surgery

— Chronic, allodynia, autonomic changes; not acute, not tense

— Spontaneous thigh/calf pain in poorly controlled diabetic; MRI shows muscle edema; supportive care, no fasciotomy

— Crepitus, foul exudate, systemic toxicity, gas on imaging; emergent debridement + penicillin + clindamycin ± hyperbaric oxygen

— Pitting → non-pitting, chronic, painless or mild ache; not acute

— Skin failure, not compartment, but extensive burns can produce ACS requiring escharotomy

Board pearl: A diabetic on a statin with bilateral thigh pain and CK 8,000 but soft compartments is statin-induced rhabdomyolysis, not ACS — stop statin, hydrate, monitor renal function. Do not fasciotomize on CK alone.

Rhabdomyolysis without ACS:

Cellulitis / erysipelas:

Septic arthritis:

Pyomyositis:

Snakebite envenomation:

Reflex sympathetic dystrophy / CRPS:

Diabetic muscle infarction:

Gas gangrene (clostridial myonecrosis):

Lymphedema:

Stevens-Johnson / TEN with extensive blistering:

Postoperative Care, Wound Management, and Long-Term Plan

— Elevate limb (post-decompression, edema reduction now beneficial)

— Neurovascular checks q1–2h × 24 h, then q4h

— Continue IV fluids titrated to UOP >1 mL/kg/h

— Trend CK, BMP q6–12h until normalizing

— DVT prophylaxis (mechanical → pharmacologic at 24 h if hemostasis secure)

— Pain control with multimodal regimen (acetaminophen, opioids; cautious NSAIDs once renal function and bleeding risk allow)

— Tetanus update if open injury

— Broad-spectrum antibiotics if contaminated; otherwise short cefazolin course

— Negative-pressure wound therapy (wound VAC) most common — improves edema, accelerates granulation

— Return to OR in 48–72 h for re-look, additional debridement, possible primary closure

— If unable to close primarily: split-thickness skin graft (typically from contralateral thigh), often 7–14 days post-fasciotomy when bed is granulated

— Some advocate "shoelace" gradual closure with vessel loops

— Definitive fixation (IM nail for tibia, plate for forearm) often performed at same OR setting or shortly after

— Coordinate fixation with closure plan

— Wound healing progressing, infection controlled, CK trending down, renal function stable, pain controlled on oral regimen, ambulation with PT (weight-bearing per fracture protocol)

— Outpatient wound care or home health for VAC management

— Wound surveillance, physical therapy for strength and ROM, treatment of contracture if it develops

— Return-to-activity timing per orthopedic surgeon

Step 3 management: Routine discharge med list after extremity fasciotomy + tibial nail: scheduled acetaminophen, short opioid taper, DOAC or LMWH for VTE prophylaxis (duration per ortho, often 2–4 weeks for lower-extremity trauma), bowel regimen, tetanus booster if not given, PCP follow-up in 1–2 weeks, ortho follow-up in 7–10 days for wound check.

Immediate postoperative orders:

Wound care:

Fracture management:

Discharge readiness:

Long-term plan:

Follow-Up, Monitoring Parameters, and Rehabilitation

— Orthopedic surgery: 7–10 days for wound and staple/suture removal; 4–6 weeks for fracture healing assessment with radiographs; subsequent visits per fracture protocol

— Primary care: 1–2 weeks post-discharge for medication reconciliation, VTE prophylaxis status, renal recovery

— Nephrology: if AKI required RRT or persistent CKD — 2–4 weeks

— Plastic surgery: if STSG done — donor and recipient site checks at 1–2 weeks

— Physical therapy: begin in-hospital, continue 2–3×/week outpatient for 6–12 weeks minimum

— Wound: signs of infection, dehiscence, hypertrophic scar

— Neurologic recovery: deep peroneal (foot drop) — may need AFO brace; reassess at 6 weeks, 3 months, 6 months; permanent if no recovery by 12–18 months

— Renal: repeat creatinine and UA at 1 week, 1 month if AKI occurred

— CK normalization (usually within 1–2 weeks)

— Early ROM to prevent contracture (Volkmann prevention even after timely fasciotomy)

— Strengthening once wound healed and fracture stable

— Gait retraining; AFO for persistent foot drop

— Functional milestones: independent ambulation, return to work, return to sport

— Realistic expectations — many patients have residual weakness, scar discomfort, or nerve deficits

— Signs of recurrent or chronic problems: chronic exertional symptoms, persistent foot drop, contracture

— Psychological impact of disfigurement and long recovery — screen for depression/PTSD especially after high-energy trauma; refer to behavioral health

— Smoking cessation (impairs wound and fracture healing)

— Tight glucose control in diabetics

Board pearl: Foot drop persisting >12 months after deep peroneal injury is generally permanent. Refer early for AFO bracing and consider tendon transfer (posterior tibialis to dorsum of foot) at 12–18 months if no recovery.

Outpatient follow-up cadence:

Monitoring parameters:

Rehabilitation goals:

Counseling:

Ethical, Legal, and Patient Safety Considerations

— ACS is life- and limb-threatening — proceed under implied consent / emergency exception if patient lacks capacity and surrogate unreachable

— When time permits, disclose: diagnosis, why fasciotomy is urgent, scar/disfigurement, need for staged closure or grafting, infection/nerve/vascular risks, alternatives (none acceptable)

— Document the urgency and rationale for any consent shortcuts

— Most common malpractice scenario: nurse documents escalating pain, on-call resident does not evaluate at bedside, fasciotomy delayed, Volkmann or amputation results

— Mitigation: bedside evaluation for any escalating pain in at-risk extremity, document neurovascular exam with each call, low threshold to consult orthopedics

— Be cautious of regional anesthesia or PCA masking pain — clearly communicate ACS risk with anesthesia

— Sign-out must include: at-risk limb, baseline neurovascular exam, pain trajectory, parameters that should trigger immediate reassessment

— "Cast room → ED → ortho floor → OR" transitions are classic failure points

— Closed-loop communication; readback orders for fasciotomy

— Suspected non-accidental trauma in pediatrics (long-bone fractures in non-ambulatory infants) → child protective services

— Intimate partner violence screening when mechanism inconsistent with injury

— Critical access hospitals without 24/7 orthopedics: protocols to decompress locally or transfer expeditiously; document time stamps to demonstrate appropriate urgency

Step 3 management: When an on-call resident receives a third pain call overnight from a casted tibia patient, the correct action is bedside evaluation and removal of the cast to skin, not telephone analgesic escalation — this is both the right clinical and the right medicolegal answer.

Informed consent in emergencies:

Pediatric consent: Obtain parental consent; if parents unavailable and limb threatened, proceed under emergency doctrine and document attempts

Capacity issues: Intoxicated or head-injured trauma patient — two-physician documentation of emergency, surrogate notification when feasible

Failure-to-diagnose liability:

Transition-of-care risk (high yield for Step 3):

Mandatory reporting:

Resource and access:

High-Yield Associations and Rapid-Fire Clinical Facts

Board pearl: The single most testable fact: fasciotomy is a clinical decision; pulse and pulse oximetry can be normal in established ACS. Pulseless = late or different diagnosis (arterial injury).

Most common cause overall: tibial diaphyseal fracture (especially young male, high-energy)

Most commonly affected compartment of the leg: anterior

Most commonly missed compartment of the leg: deep posterior — always release in 4-compartment fasciotomy

Earliest sensory deficit in anterior leg ACS: first dorsal web space (deep peroneal nerve)

Earliest sign overall: pain out of proportion + pain with passive stretch

Pediatric mnemonic: 3 A's — Anxiety, Agitation, increasing Analgesia

Threshold for fasciotomy: ΔP (DBP − compartment pressure) ≤ 30 mmHg

Time window for reversible muscle injury: <4–6 h ischemia; >8 h irreversible necrosis begins

Volkmann ischemic contracture: late sequela of missed forearm ACS, classically after supracondylar humerus fracture in children

Reperfusion fasciotomy: prophylactic after >4–6 h of arterial occlusion repaired

Crush injury "smiling K": released potassium with reperfusion → cardiac arrest; pretreat with calcium, bicarbonate, insulin/dextrose

Urine dipstick heme-positive without RBCs = myoglobinuria (also seen with hemoglobinuria)

Pigment nephropathy threshold: CK >5,000 raises risk; >15,000–20,000 high risk

Anticoagulant-related spontaneous ACS: classic in thigh from quadriceps hematoma; reverse anticoagulation

Compartment counts: leg 4, thigh 3, forearm 3, hand 10, foot 9, gluteal 3

Lithotomy-position complication: well-leg compartment syndrome during prolonged urologic/gynecologic surgery — drop legs periodically

Reperfusion electrolyte cocktail: hyperK, hyperphosphatemia, hypocalcemia, lactic acidosis

"Skin is a compartment": short fasciotomy incisions fail — full-length skin and fascia release

Re-look OR: standard at 48–72 h

Compartment of the abdomen: bladder pressure >20 mmHg with new organ dysfunction = abdominal compartment syndrome

Board Question Stem Patterns

— Young man, tibia fracture in long-leg cast, calls for more morphine, pain on passive toe extension → answer is bivalve cast and emergent fasciotomy, NOT MRI, NOT pressure measurement first

— Intubated polytrauma, tibial plateau fracture, sedated → answer is measure compartment pressures (clinical exam unreliable)

— Popliteal artery injury repaired after 7 h of ischemia → next step is prophylactic 4-compartment fasciotomy at the same operative setting

— Child with supracondylar humerus fracture, increasing analgesia requirement, pain on finger extension → forearm fasciotomy with carpal tunnel release to prevent Volkmann

— Warfarin user with INR 5, fell, now tense painful thigh → reverse with 4-factor PCC + vitamin K, emergent thigh fasciotomy

— Tibia ORIF with continuous popliteal block, nurse reports tense leg but patient reports no pain → high suspicion (block masks pain) → measure pressures, fasciotomy if ΔP ≤30

— Marathon runner, CK 30,000, dark urine, soft compartments → IV fluids, monitor potassium and renal function; no fasciotomy

— Crotalid bite, swollen forearm → antivenom (CroFab) first, measure pressures; fasciotomy only if ΔP ≤30 despite antivenom

— Patient s/p fasciotomy with persistent foot drop at 12 months → AFO + consider tendon transfer

— Resident managed pain by phone overnight, missed ACS → answer is bedside evaluation should have occurred

Key distinction: When the stem mentions a palpable pulse, do not be tricked into excluding ACS. When it mentions a tense, woody compartment with pain on passive stretch — that is ACS until proven otherwise, and the next step is fasciotomy or pressure measurement depending on exam reliability.

Pattern 1 — Tibial fracture with escalating pain:

Pattern 2 — Obtunded ICU/trauma patient:

Pattern 3 — Reperfusion scenario:

Pattern 4 — Pediatric supracondylar fracture:

Pattern 5 — Anticoagulated elderly:

Pattern 6 — Postoperative regional anesthesia:

Pattern 7 — Rhabdomyolysis without ACS:

Pattern 8 — Snakebite swelling:

Pattern 9 — Foot drop after recovery:

Pattern 10 — Litigation/safety:

One-Line Recap

Acute compartment syndrome is a clinical, time-critical diagnosis whose definitive treatment is emergent open fasciotomy of all involved compartments — do not wait for imaging, do not be reassured by a palpable pulse, and act when ΔP ≤ 30 mmHg or the exam is convincing.

Board pearl: If you remember only one number, remember 30 mmHg — the ΔP threshold for fasciotomy. If you remember only one action, remember see the patient at the bedside when called about escalating pain in a fractured or casted limb. These two reflexes catch the vast majority of board-tested and real-world acute compartment syndrome scenarios.

Recognize: pain out of proportion + pain with passive stretch + tense compartment in an at-risk limb (tibial fracture, crush, reperfusion, anticoagulated bleed, obtunded patient) — the 5 P's of pallor/pulselessness/paralysis are late; rely on pain and tenseness

Decide: awake reliable patient → fasciotomy on clinical grounds; obtunded/equivocal → measure compartment pressures, fasciotomy if ΔP = DBP − compartment pressure ≤ 30 mmHg

Act: remove circumferential dressings, keep limb at heart level, resuscitate to restore perfusion, mobilize ortho STAT, full-length skin-and-fascia release of all four leg compartments (or analogous compartments elsewhere) with deep posterior never forgotten; leave wounds open, return to OR in 48–72 h for closure

Protect: treat rhabdomyolysis with aggressive IV fluids targeting UOP 1–2 mL/kg/h, monitor and treat hyperkalemia, watch for reperfusion injury, prophylax VTE once hemostatic, follow long-term for nerve recovery (foot drop), wound closure, fracture healing, and psychosocial sequelae