During operative stabilisation of a femoral shaft fracture, a tourniquet is inadvertently left inflated for 3.5 hours. Postoperatively the patient has foot drop and loss of dorsal foot sensation. The nerve injury is most likely at which level and of which type?

• A Deep peroneal nerve at ankle; neurapraxia (Sunderland grade 1)
• B Sciatic nerve at greater sciatic notch; neurotmesis (Sunderland grade 5)
• C Common peroneal nerve at fibular neck; axonotmesis (Sunderland grade 2) ✓
• D Tibial nerve at popliteal fossa; axonotmesis (Sunderland grade 2)

Explanation

Prolonged tourniquet application at the thigh causes focal demyelination and mechanical compression injury most severely at the common peroneal nerve as it winds around the fibular neck, where it has least soft-tissue padding. The resulting foot drop and dorsal sensory loss match the common peroneal distribution. The injury is typically axonotmesis (Sunderland 2) with intact epineurium, allowing spontaneous recovery over months. Neurotmesis and tibial/sciatic levels are incorrect for tourniquet palsy.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.