Following posterior hip dislocation, a patient develops foot drop with preserved knee flexion and hamstring function. Which nerve is most specifically injured?

• A Tibial division of sciatic nerve
• B Common peroneal (fibular) division of sciatic nerve ✓
• C Femoral nerve
• D Obturator nerve

Explanation

In posterior hip dislocation, the sciatic nerve is at risk, but the common peroneal division is more vulnerable than the tibial division because its fibres lie more laterally and superficially within the sciatic nerve. Isolated common peroneal injury causes foot drop (loss of ankle dorsiflexion and eversion) with sensory loss over the dorsum of the foot and lateral lower leg, but hamstring function (tibial division) and plantar flexion are preserved. At the fibular neck, the common peroneal nerve is also vulnerable to fractures, pressure palsies from tight casts, and prolonged squatting.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.