Which of the following is a likely contributor to tarsal tunnel syndrome?

• A. Extensor hallucis longus trauma
• B. Flexor hallucis longus trauma
• C. Fracture of the calcaneus
• D. Distal fibula fracture

Answer: (B)

Tarsal tunnel syndrome happens when the tibial nerve is compressed as it passes through the tarsal tunnel behind the medial malleolus. Inside that confined space lie the tendons of the tibialis posterior, flexor digitorum longus, and flexor hallucis longus, along with the nerve and vessels. When one of these tendons’ sheaths becomes inflamed or swollen from trauma—especially the flexor hallucis longus—the pressure within the tunnel increases, compressing the nerve and producing symptoms like burning, tingling, or numbness in the sole of the foot.

Trauma to the flexor hallucis longus is therefore a plausible contributor because it directly affects a structure that resides inside the tunnel and can raise intratunnel pressure through inflammation or swelling. In contrast, injuries to the extensor hallucis longus occur on the front of the leg and do not involve the structures within the tarsal tunnel; fractures of the calcaneus or distal fibula can cause pain and swelling but are less likely to produce the characteristic nerve compression seen with tarsal tunnel syndrome unless they lead to secondary tunnel swelling, which is not as direct a cause.