Review Question - QID 4545

Decreased extensor hallucis longus strength is the physical exam finding most consistent with transient peroneal nerve neurapraxia.

Transient peroneal nerve neuropraxia has been noted in up to 5% of patients undergoing closed nailing of tibial shaft fractures. This is of unknown etiology, although injury to the peroneal nerve branches can be from placement of the interlocking screws into the nail. In this syndrome, extensor hallucis longus weakness is noted and decreased sensation is seen in the 1st dorsal webspace (deep peroneal nerve distribution). These symptoms generally begin improving by 3 months and have variable rates of recovery.

Robinson et al. reported on 'dropped hallux' syndrome, with weakness of extensor hallucis longus and numbness in the first web space, without clinical involvement of extensor digitorum longus or tibialis anterior. They found this in 5% of their patients after tibial nailing of closed tibia fractures, and all recovered either partially or completely by 4 months.

Lawrence et al. performed an anatomic study that reported the deep peroneal nerve was located superficial to the anterior tibial artery between the tibialis anterior and extensor hallucis longus muscles in the distal one third of the leg. They also found that the deep peroneal nerve crossed deep to the extensor hallucis longus tendon to enter the interval between the extensor hallucis longus and extensor digitorum longus at an average distance of 12.5 mm proximal to the ankle.

Figure A shows a tibial shaft fracture with mild displacement.

Incorrect Answers:
Answer 1: Lateral hindfoot sensation is generally via the sural nerve.
Answer 2: Achilles reflex is via S1 roots.
Answer 3: The peroneus longus is innervated by the superficial peroneal nerve.
Answer 5: Plantar forefoot sensation is via the tibial nerve along with the medial and lateral plantar branches.