A patient develops foot drop after total hip replacement in the left lateral decubitus position. Which nerve and which part of it is most likely injured?
- A Common peroneal division of the sciatic nerve — more susceptible to stretch injury ✓
- B Tibial division of the sciatic nerve — most medial part
- C Femoral nerve compressed under the inguinal ligament
- D Obturator nerve in the obturator canal
Correct answer: A. Common peroneal division of the sciatic nerve — more susceptible to stretch injury
Explanation
Foot drop after hip surgery is most commonly due to injury to the common peroneal (fibular) component of the sciatic nerve. The common peroneal division has less connective tissue investment, fewer fascicles, and tethering at the sciatic notch and fibular neck, making it more vulnerable to traction. Foot drop results from loss of dorsiflexion (anterior compartment muscles) and eversion (peroneal muscles). The tibial component controls plantar flexion and is relatively protected. Femoral nerve injury causes quadriceps weakness with loss of knee extension, not foot drop.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.