Acute compartment syndrome (ACS) of the leg is a time-sensitive surgical emergency caused by increased pressure within a closed fascial compartment, leading to decreased tissue perfusion, ischemia, and potentially irreversible necrosis within 6 hours of impaired perfusion. [1-2] The lower leg is the most common location, with the anterior compartment most frequently affected. [2] Incidence is approximately 3.1 per 100,000/year with a strong male predominance (10:1). [3]
1. History
- Mechanism of injury: Fracture (tibial shaft fractures are the #1 cause), crush injury, high-energy trauma, vascular injury/reperfusion, burns, prolonged immobilization ("found down"), or iatrogenic (tight cast/dressing, IV infiltration) [2-3]
- Pain characterization: Severe, deep, unrelenting pain that is out of proportion to the injury — the hallmark symptom. Pain initially controlled that becomes refractory to escalating analgesics is highly concerning [1-2]
- Timing: Onset can be minutes to hours after the inciting event; most commonly develops within 24–48 hours of injury [1]
- Progression: Ask about worsening pain trajectory, numbness/tingling, and weakness
- Associated symptoms: Paresthesias (especially first web space — deep peroneal nerve), swelling, tightness, difficulty moving toes [2]
- Important negatives: Absence of pain does NOT rule out ACS in obtunded, sedated, or regionally anesthetized patients [2]
2. Alarm Features
- Pain refractory to appropriate analgesia (most reliable early sign) [1-2]
- Pain with passive stretch of the involved compartment muscles (e.g., passive plantarflexion of toes stretches anterior compartment) [1-2]
- Progressive paresthesias — altered sensation in the first web space suggests anterior compartment involvement [2]
- Tense, "woody" compartment on palpation (low sensitivity/specificity but raises suspicion) [1]
- Late/ominous signs (do NOT wait for these): Paralysis, pallor, pulselessness — these are signs of arterial ischemia and indicate irreversible damage is likely [2]
- Pearl: The traditional "5 Ps" mnemonic is misleading for ACS. As von Keudell et al. emphasize: "If the patient is awake, the five Ps to consider are pain, pain, pain, pain, and pain" [2]
- Pediatric red flags: The "3 As" — Agitation, Anxiety, and increasing Analgesic requirements [2]
3. Medications
- Contributors to ACS risk:
- Anticoagulants (warfarin, DOACs, heparin) — increase bleeding into compartments [1][4]
- Opioids/sedatives — may mask pain, delaying diagnosis [5]
- Regional anesthesia/epidural catheters — should be avoided in high-risk patients as they mask symptoms [2]
- Medications to avoid: Epidural pain catheters in patients at risk for ACS [2]
- Acute treatment medications:
- IV opioid analgesia for pain control (do NOT withhold — but escalating requirements should raise suspicion) [4]
- IV crystalloid for resuscitation and rhabdomyolysis prevention
- Sodium bicarbonate if metabolic acidosis/myoglobinuria develops
- Pharmacovigilance: An FAERS analysis identified ~100 drugs associated with compartment syndrome reports, with a median onset of 45 days [6]
4. Diet
- Not a primary consideration in acute management
- Hydration is critical — aggressive IV fluid resuscitation to prevent renal injury from rhabdomyolysis/myoglobinuria [2][7]
- NPO status should be maintained if fasciotomy is anticipated
5. Review of Systems
- Musculoskeletal: Pain severity, location, progression; ability to move toes/ankle
- Neurologic: Numbness, tingling, weakness, altered sensation in specific nerve distributions
- Renal/GU: Dark or tea-colored urine (myoglobinuria) [2]
- Cardiovascular: Symptoms of hypotension, tachycardia (systemic effects of rhabdomyolysis)
- Constitutional: Fever (consider infectious etiology — Group A Streptococcus can cause ACS) [2]
6. Collateral History and Family History
- Collateral: Mechanism and timing of injury, duration of immobilization, substance use (opioid overdose → "found down" → crush/compartment syndrome) [5]
- Medications: Anticoagulant use, recent regional anesthesia
- Social context: Illicit drug use or alcohol consumption — significant predictive factors for rhabdomyolysis in traumatic compartment syndrome (OR 5.91) [7]
- Family history: Bleeding disorders may increase risk [2]
7. Risk Factors
- Tibial shaft fractures (most common cause; ACS occurs in 1–9% of lower extremity fractures) [2-3]
- High-energy tibial plateau fractures and knee fracture-dislocations [2]
- Young males (highest incidence) [3]
- Crush injuries and "found down" patients [5]
- Anticoagulant use [1]
- Burns (especially circumferential) [2]
- Vascular injury with reperfusion [3]
- Prolonged lithotomy positioning during surgery [2]
- Constrictive casts, dressings, or splints [2]
- Massive fluid resuscitation [8]
- Open fractures (do NOT exclude ACS) [2]
8. Differential Diagnosis
- Acute arterial ischemia — pallor, pulselessness, and paralysis are more characteristic of arterial occlusion than ACS; check ABI/pulses [2]
- Deep vein thrombosis — swelling and pain but typically less severe; no pain with passive stretch
- Cellulitis/necrotizing fasciitis — erythema, fever, systemic toxicity; crepitus in necrotizing infection
- Fracture pain — expected post-fracture pain should improve with immobilization, not worsen
- Rhabdomyolysis without ACS — elevated CK, dark urine, but no tense compartment
- Peripheral nerve injury — paresthesias/weakness from direct nerve trauma rather than ischemia
- Chronic exertional compartment syndrome — exercise-induced, bilateral, resolves with rest; distinct from acute ACS
9. Past Medical History
- Prior compartment syndrome episodes
- Bleeding disorders or coagulopathy [2]
- Peripheral vascular disease
- Chronic kidney disease (lower threshold for renal injury from myoglobinuria)
- Recent surgery (especially with lithotomy positioning) [2]
- Nephrotic syndrome [2]
10. Physical Exam
- Vital signs: Tachycardia and hypotension may indicate systemic complications (rhabdomyolysis, hemorrhage)
- Inspection: Swelling, ecchymosis, skin changes; assess for circumferential burns/dressings
- Palpation: Tense, firm ("woody") compartment — compare to contralateral limb. Low sensitivity/specificity but raises clinical suspicion [1-2]
- Pain with passive stretch: The key provocative maneuver
- Anterior compartment: Pain with passive plantarflexion of toes
- Lateral compartment: Pain with passive inversion of foot
- Deep posterior compartment: Pain with passive dorsiflexion of toes
- Superficial posterior compartment: Pain with passive dorsiflexion of ankle
- Neurologic exam:
- First web space sensation (deep peroneal nerve → anterior compartment) [2]
- Lateral foot sensation (superficial peroneal nerve → lateral compartment)
- Extensor hallucis longus strength (deep peroneal nerve) [2]
- Pulses: Typically preserved until very late — pulselessness is NOT a reliable early sign [2]
- Pearl: A single exam is unreliable; serial examinations every 1–2 hours for 24–48 hours are required in high-risk patients [1]
11. Lab Studies
- Creatine kinase (CK): Elevated with muscle necrosis/rhabdomyolysis; serial monitoring recommended [4][7]
- Basic metabolic panel: Hyperkalemia (life-threatening), metabolic acidosis, elevated creatinine [2]
- Urinalysis: Myoglobinuria (dipstick positive for blood without RBCs on microscopy)
- Serum myoglobin: Elevated; correlates with renal injury risk
- CBC: Baseline; leukocytosis may suggest infection
- Coagulation studies: If on anticoagulants or coagulopathy suspected
- Lactate: May be elevated with tissue ischemia
- Type and screen: In anticipation of surgery
12. Imaging
- X-ray of the affected extremity: First-line to identify fractures (the most common cause of ACS) [2]
- CT angiography: If arterial injury is suspected as the etiology or to differentiate from acute arterial ischemia
- MRI: Not routinely indicated acutely; may show muscle edema but should NOT delay treatment
- Ultrasound: Limited role; may help identify hematoma or vascular injury
- Pearl: Imaging should never delay clinical assessment or surgical consultation. ACS is a clinical diagnosis [1][9]
13. Special Tests
- Intracompartmental pressure (ICP) measurement (Stryker device):
- Indicated when clinical exam is equivocal or unobtainable (obtunded, sedated, pediatric, regional anesthesia) [1]
- Measure within 5 cm of the fracture site and in all four compartments [2]
- Normal compartment pressure: ~8 mmHg in adults, 10–15 mmHg in children [2]
- ΔP (delta pressure) = Diastolic BP − Compartment Pressure
- ΔP < 30 mmHg → fasciotomy indicated (preferred over absolute thresholds) [1-2]
- Absolute pressures of 30–45 mmHg have low specificity and may lead to unnecessary fasciotomies [3]
- Continuous ICP monitoring (sensitivity 94%, specificity 98% in one study) is valuable but not yet standard practice [3]
- Near-infrared spectroscopy (NIRS): Noninvasive tissue oxygenation monitoring under investigation; most promising noninvasive modality but awaiting clinical trial validation [10]
- Point-of-care ultrasound: Limited diagnostic utility for ACS itself
The following figure from a JAMA Surgery systematic review illustrates the three most commonly used invasive ICP measurement devices:
14. ECG
- Indicated if hyperkalemia is suspected (from rhabdomyolysis/muscle necrosis)
- Dangerous patterns: Peaked T waves, widened QRS, sine wave pattern, bradycardia — all signs of hyperkalemia requiring emergent treatment [2]
- Cardiac arrhythmias can result from the release of hyperkalaemic and acidic blood from necrotic muscle [2]
15. Assessment
- ACS is a clinical diagnosis made primarily by history and serial physical examination in awake, alert patients [1]
- The diagnosis evolves over time — a single normal exam does not exclude ACS [1]
- Irreversible nerve damage can begin as early as 4 hours; irreversible muscle necrosis occurs by 6 hours [1-2]
- Up to 30% of cases occur without fracture [2]
- Complications of missed/delayed ACS: Contractures (ankle/foot), foot drop, sensory neuropathy, rhabdomyolysis (44% of traumatic ACS patients), acute kidney injury (39% of those with rhabdomyolysis), amputation, and death [2][7][11]
16. Treatment Plan
Immediate stabilization
- Remove all constrictive dressings, casts, and splints — bivalve and spread casts [2]
- Position limb at heart level (elevation above heart level may decrease perfusion pressure) [2]
- Aggressive IV fluid resuscitation (target urine output 1–2 mL/kg/hr if rhabdomyolysis suspected)
- Treat hyperkalemia emergently if present (calcium gluconate, insulin/dextrose, kayexalate)
- Adequate analgesia — escalating requirements should heighten suspicion, not lead to withholding pain control
Definitive treatment — Emergent fasciotomy
- Four-compartment fasciotomy is the standard of care [2]
- Two-incision technique (most common): Lateral incision centered over the intermuscular septum (releases anterior + lateral compartments) and medial incision 2 cm posterior to the subcutaneous tibial border (releases superficial + deep posterior compartments) [2]
- Single-incision technique: Equally effective in cadaveric studies; may reduce need for skin grafting [12-13]
- Incisions must be long and generous (20–30 cm) [1]
- Wounds left open — early closure is associated with recurrence [2]
- Wound management: Vessel loop/elastic band approximation, moist dressings, or vacuum-assisted closure; return to OR at 48–72 hours for repeat debridement and staged closure [2][12]
- Split-thickness skin grafts if primary closure not possible [2]
If ACS is missed >24–48 hours with no residual muscle function: Non-surgical management with hydration, pain control, splinting, and debridement of necrotic tissue to prevent systemic complications [2]
17. Disposition
- Admission criteria: All confirmed or suspected ACS cases require admission — this is a surgical emergency [1][9]
- ICU admission: If rhabdomyolysis with AKI, hyperkalemia, metabolic acidosis, or hemodynamic instability [2]
- Surgical consultation: Immediate orthopedic surgery or trauma surgery consultation at the time of clinical suspicion — do not delay for confirmatory testing [9]
- Transfer: If fasciotomy capability is not available, emergent transfer to a facility with surgical capability
- Observation: High-risk patients (tibial fractures, crush injuries) require serial exams every 1–2 hours for 24–48 hours even if initial exam is reassuring [1]
18. Follow Up / Return Precautions
- Post-fasciotomy: Return to OR at 48–72 hours for wound assessment, debridement, and staged closure [2][12]
- Outpatient follow-up: Wound checks, physical therapy for passive stretching and contracture prevention, and monitoring for chronic venous insufficiency (most common long-term complication of fasciotomy) [3]
- Return precautions (for patients discharged with high-risk injuries before ACS develops):
- Return immediately for worsening pain not controlled by medications, numbness/tingling, inability to move toes, or swelling
- Loosen or remove any splints/wraps if pain worsens
- Expected recovery: Most patients who undergo timely fasciotomy return to pre-injury activity levels, though quality of life scores remain lower than controls [2]
- Complications to counsel about: Fasciotomy scars (20–30 cm), potential need for skin grafting, chronic venous insufficiency, residual sensory deficits, and possible contractures [3][14]
References
1. Best Practices In The Management Of Orthopaedic Trauma. — Matthew L. Davis MD FACS, Gregory J. Della Rocca MD PhD FACS, Megan Brenner MD MS RPVI FACS, et al American College of Surgeons (2015). 2015.
2. Diagnosis and Treatment of Acute Extremity Compartment Syndrome. — von Keudell AG, Weaver MJ, Appleton PT, et al. Lancet. 2015.
3. Diagnostic Modalities for Acute Compartment Syndrome of the Extremities: A Systematic Review. — Mortensen SJ, Vora MM, Mohamadi A, et al. JAMA Surgery. 2019.
4. Best Practices Guidelines For Acute Pain Management In Trauma Patients. — Andrew Bernard, Douglas R. Oyler PharmD, Jeffrey O. Anglen MD FACS FAAOS, et al American College of Surgeons (2020). 2020.
5. Traumatic Rhabdomyolysis: Crush Syndrome, Compartment Syndrome, and the 'Found Down' Patient. — Fernandez JJ, Smith SR. The Journal of the American Academy of Orthopaedic Surgeons. 2024.
6. Compartment Syndrome Associations With Drugs: A Pharmacovigilance Study of the FDA Adverse Event Reporting System (FAERS). — Kong W, Shu Y, Tang J, Wan J, Yang X. Expert Opinion on Drug Safety. 2025.
7. High Risk of Rhabdomyolysis and Acute Kidney Injury After Traumatic Limb Compartment Syndrome. — Tsai WH, Huang ST, Liu WC, et al. Annals of Plastic Surgery. 2015.
8. Compartment Syndromes From Head to Toe. — Balogh ZJ, Butcher NE. Critical Care Medicine. 2010.
9. Evaluation and Management of Acute Compartment Syndrome in the Emergency Department. — Long B, Koyfman A, Gottlieb M. The Journal of Emergency Medicine. 2019.
10. Noninvasive Diagnostics for Extremity Compartment Syndrome Following Traumatic Injury: A State-of-the-Art Review. — Walters TJ, Kottke MA, Hargens AR, Ryan KL. The Journal of Trauma and Acute Care Surgery. 2019.
11. Acute Compartment Syndrome in the Athlete. — Farah O, Farah G, Mumuni S, Volchenko E, Hutchinson MR. Clinics in Sports Medicine. 2023.
12. Single-Incision 4-Compartment Fasciotomy of the Lower Leg: Safe, Effective, and Advantageous. — Chang G, Fram B, Krieg JC. Orthopedics. 2020.
13. The Efficacy of a Single-Incision Versus Two-Incision Four-Compartment Fasciotomy of the Leg: A Cadaveric Model. — Neal M, Henebry A, Mamczak CN, Ruland R. Journal of Orthopaedic Trauma. 2016.
14. Compartment Syndrome of the Lower Leg and Foot. — Frink M, Hildebrand F, Krettek C, Brand J, Hankemeier S. Clinical Orthopaedics and Related Research. 2010.