Fibular neck fracture risks injury to which nerve, potentially causing foot drop?

• A. Tibial nerve
• B. Common peroneal (fibular) nerve
• C. Sural nerve
• D. Obturator nerve

Answer: (B)

The common peroneal nerve is at risk with a fibular neck fracture because it runs right around the neck of the fibula and is exposed there. When this nerve is injured, the muscles that dorsiflex the foot and extend the toes—primarily the tibialis anterior and the toe extensors via the deep peroneal branch—lose function, leading to foot drop. You may also see eversion weakness from the superficial peroneal branch, but the key feature is the inability to lift the front of the foot. In contrast, injury to the tibial nerve would mainly affect plantarflexion and sole sensation, the sural nerve is a sensory branch to the posterior-lateral leg and foot, and the obturator nerve controls thigh adductors. So injury to the common peroneal nerve at the fibular neck best explains the risk of foot drop.