A 26-year-old man is evaluated in the hospital 6 hours after undergoing open reduction and internal fixation for a closed right tibial shaft fracture sustained in a motorcycle accident. He reports escalating pain in the right leg that is deep, severe, and not relieved by intravenous morphine. He also notes numbness over the top of the foot. Vital signs are temperature 37.2°C (99.0°F), blood pressure 126/78 mmHg, pulse 104/min, and respirations 18/min. On physical examination, the right leg is swollen and tense to palpation. Pain is significantly worsened by passive dorsiflexion of the foot. Sensation is decreased over the dorsum of the foot, and active toe extension is weak. Pedal pulses are palpable and symmetric bilaterally.
A) Acute compartment syndrome
Acute compartment syndrome (ACS) occurs when increased pressure within a closed fascial compartment impairs capillary perfusion, leading to tissue ischemia. It most commonly follows long bone fractures, particularly of the tibia, and may also result from crush injury, reperfusion injury, or tight bandaging. The earliest and most reliable signs are pain out of proportion to injury and pain with passive stretch of the involved muscles. Paresthesia (e.g., numbness), motor weakness, and a firm, tense compartment often follow. Pulselessness is a late finding, so the presence of normal pulses should not delay diagnosis. Compartment syndrome is a surgical emergency requiring emergent fasciotomy to prevent permanent nerve and muscle damage. Remember the 5 Ps: Pain, Pallor, Paresthesia, Paralysis, and Pulselessness (late).
Answer choice B: Deep vein thrombosis, is incorrect. Deep vein thrombosis (DVT) can cause unilateral leg swelling and pain, but it does not cause severe pain with passive stretch or neurologic symptoms such as numbness or weakness. It also develops over days and is less likely in the immediate postoperative period, especially with anticoagulant prophylaxis is administered, though that information is not provided in the vignette. The tense, tender compartment and neurologic deficits in this case point to ACS.
Answer choice C: Fat embolism syndrome, is incorrect. Fat embolism occurs 24–72 hours after long bone fractures and classically presents with respiratory distress, neurologic abnormalities, and a petechial rash. This patient has no signs of respiratory distress, hypoxia, altered mental status, or systemic illness, and his symptoms are localized to the injured leg.
Answer choice D: Necrotizing fasciitis, is incorrect. Necrotizing fasciitis may present with severe pain and systemic signs, but patients are usually febrile, ill-appearing, and may have skin changes such as bullae, erythema, or crepitus. This patient is afebrile, normotensive, and has no skin findings. His pain is exacerbated by passive stretch and localized to a known injured compartment—hallmarks of ACS.
Answer choice E: Postoperative wound infection, is incorrect. Wound infections typically present with localized redness, warmth, tenderness, and sometimes purulent drainage or fever. This patient is afebrile and lacks signs of infection. Moreover, wound infections typically do not cause pain with passive stretch or focal neurologic symptoms, both of which are characteristic of compartment syndrome.
Key Learning Point
Acute compartment syndrome is a limb-threatening emergency. The most important early signs are pain out of proportion to injury, pain with passive stretch, and tense swelling. Sensory and motor deficits are later signs. Pulses may be normal as pulselessness is a late sign. Emergent fasciotomy is required to preserve limb function.
