Musculoskeletal · Trauma and Orthopedics
The facts most likely to be tested
The most sensitive and earliest clinical finding of compartment syndrome is pain out of proportion to injury that is exacerbated by passive stretch of the affected muscles.
The 6 Ps of compartment syndrome include pain, pallor, paresthesia, pulselessness, paralysis, and poikilothermia, though pulselessness is a late and ominous sign.
The definitive diagnosis is established by measuring intracompartmental pressure with a delta pressure (diastolic blood pressure minus compartment pressure) of ≤ 30 mmHg indicating the need for intervention.
The most common site for acute compartment syndrome is the anterior compartment of the lower leg following a tibial shaft fracture.
Immediate management requires the removal of all constrictive dressings or casts and maintaining the limb at the level of the heart to optimize perfusion pressure.
The gold standard definitive treatment is an urgent emergent fasciotomy to release the pressure within the affected fascial compartments.
Failure to treat compartment syndrome promptly leads to rhabdomyolysis, myoglobinuria, and permanent Volkmann ischemic contracture.
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A 24-year-old male is brought to the emergency department after a high-speed motorcycle accident resulting in a closed tibial shaft fracture. He underwent closed reduction and splinting in the field. Upon arrival, he reports severe, unrelenting pain in his lower leg that is not relieved by morphine. On physical exam, the calf is tense and swollen to palpation, and he experiences excruciating pain with passive extension of the toes. His distal pulses are palpable, and capillary refill is normal.
What is the most appropriate next step in management?
Emergent fasciotomy
The patient presents with classic signs of compartment syndrome, specifically pain out of proportion to injury and pain with passive stretch; because the diagnosis is clinical, immediate surgical decompression via fasciotomy is required to prevent permanent muscle necrosis.
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Etiology / Epidemiology
Most common after tibial shaft fractures or crush injuries. Increased pressure within a closed osteofascial space leads to ischemia.
Clinical Manifestations
Classic pain out of proportion to injury. Pain with passive stretch is the earliest and most sensitive clinical sign.
Diagnosis
Gold standard is intracompartmental pressure monitoring. Delta pressure < 30 mmHg is diagnostic.
Treatment
Immediate fasciotomy. Do not elevate the limb above the heart as it decreases perfusion pressure.
Prognosis
Risk of rhabdomyolysis and permanent nerve damage. Time to decompression is the primary determinant of outcome.
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Epidemiology & Etiology
Occurs when tissue pressure exceeds capillary perfusion pressure, causing microvascular compromise. Tibial fractures are the most common cause in adults, while supracondylar humerus fractures are the most common in children. High-energy trauma, burns, and prolonged limb compression are significant risk factors.
Pertinent Anatomy
The body is divided into osteofascial compartments with non-compliant boundaries. The anterior compartment of the lower leg is the most frequently involved site due to its rigid boundaries and limited expansion capacity.
Pathophysiology
Increased volume (edema, hemorrhage) within a fixed space elevates interstitial pressure. This reduces the arteriovenous gradient, leading to ischemia and cellular death. If untreated, this progresses to Volkmann's contracture and irreversible muscle necrosis.
Clinical Manifestations
The hallmark is pain out of proportion to injury that is exacerbated by passive stretching of the affected muscles. The 6 Ps (pain, pallor, pulselessness, paresthesia, poikilothermia, paralysis) are late findings; pulselessness is a pre-terminal sign and should not be awaited for diagnosis.
Diagnosis
Clinical diagnosis is primary, but intracompartmental pressure monitoring is the gold standard for equivocal cases. A delta pressure (diastolic BP minus compartment pressure) ≤ 30 mmHg confirms the diagnosis. Serial physical exams are mandatory in high-risk patients.
Treatment
Emergent surgical fasciotomy is the definitive treatment to release all involved compartments. Avoid limb elevation and remove all constrictive dressings/casts immediately. If the patient is hypotensive, restore systemic blood pressure to maintain perfusion.
Prognosis
Delayed treatment leads to rhabdomyolysis, which can cause acute kidney injury due to myoglobinuria. Permanent nerve damage and muscle fibrosis are common if decompression is delayed beyond 6 hours.
Differential Diagnosis
DVT: presents with calf swelling but lacks pain with passive stretch
Cellulitis: presents with erythema and warmth, not tense compartments
Peripheral nerve injury: presents with sensory loss without tense, painful muscles
Fracture pain: usually relieved by immobilization and analgesia
Rhabdomyolysis: systemic muscle breakdown without localized compartment tension