A 30-year-old male presents with right leg pain after falling off a dirt bike. He denies numbness or weakness. Exam shows diffuse swelling and ecchymosis to the shin. The anterior tibial compartment is firm. An X-ray is shown. Which of the following findings is the earliest for this complication?

• A. Pain out of proportion
• B. Numbness
• C. Paresthesias
• D. Decreased sensation over dorsum of foot

Answer: (A)

Acute compartment syndrome resultswhen pressure rises within a closed muscle compartment, compromising perfusion. The earliest finding is pain that is out of proportion to the exam, often felt as severe, escalating pain and pain with passive stretching of the affected muscles. Numbness, paresthesias, and decreased sensation over the dorsum of the foot reflect nerve involvement that tends to occur later as ischemia progresses. Pulses can remain present until late stages. In this scenario, the patient has swelling and a firm anterior compartment, so the first warning sign you’d expect is pain out of proportion to what you see on exam.