A 35-year-old sustains a posterior dislocation of the hip in an RTA. Immediately after reduction, he develops wasting of the gluteus maximus, sensory loss over the posterior thigh, and inability to dorsiflex the ankle. Which nerve is injured and what is the most likely mechanism?

• A Femoral nerve — compressed in femoral triangle during dislocation
• B Superior gluteal nerve — injured during posterior approach to hip
• C Obturator nerve — tented over the femoral head during posterior dislocation
• D Sciatic nerve — stretched or contused as the femoral head displaces posteriorly; common peroneal division most vulnerable ✓

Explanation

Sciatic nerve injury complicates 10–20% of posterior hip dislocations; the nerve passes posterior to the hip joint, and posterior displacement of the femoral head stretches, compresses, or contuses the sciatic nerve as it exits through the greater sciatic notch. The common peroneal division is more vulnerable than the tibial division because of its tethering by the short head of biceps femoris and its lateral position. This produces foot drop (dorsiflexion loss), eversion weakness, and sensory loss over the dorsum of the foot alongside posterior thigh involvement (hamstrings). Immediate reduction reduces ongoing neural ischaemia.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.