Tarsal Tunnel Syndrome

The tarsal tunnel is a narrow passageway on the inner side of the ankle, formed by the medial ankle bones and roofed by the flexor retinaculum — a thick band of connective tissue. Within this tunnel run the posterior tibial nerve, the posterior tibial artery and vein, and the flexor tendons serving the toes. When the contents of this tunnel are compressed or the nerve is stretched, the result is tarsal tunnel syndrome — often called the carpal tunnel syndrome of the foot, because the mechanism parallels the median nerve compression at the wrist that most people are familiar with.

The posterior tibial nerve divides within the tarsal tunnel into the medial and lateral plantar nerves, which supply sensation to the plantar surface of the foot and motor function to the intrinsic muscles of the foot. Compression of the tibial nerve produces its characteristic symptoms in these distributions — burning, tingling, shooting, or aching pain along the inner ankle, into the arch, across the heel, and into the toes. Symptoms are typically worse with prolonged standing and walking and may wake patients from sleep in more severe cases.

The most common cause of tarsal tunnel syndrome is structural — anything that reduces the space within the tunnel or increases the tension on the nerve. Flat feet and overpronation are among the most significant biomechanical contributors: as the medial arch collapses during weight bearing, the calcaneus tilts outward, which stretches the tibial nerve across the medial ankle with every step. Space-occupying lesions within the tunnel — a ganglion cyst, varicose veins, lipoma, or bone spur — can also compress the nerve directly. Prior ankle fractures and chronic ankle swelling are additional predisposing factors.

Tarsal tunnel syndrome is frequently misdiagnosed. Its plantar burning and heel pain can be confused with plantar fasciitis — and the two conditions can coexist. The neurological character of tarsal tunnel symptoms — burning, tingling, and radiation into the toes — distinguishes it from the mechanical morning heel pain of plantar fasciitis, though this distinction is not always clear to patients or to non-specialist providers. A positive Tinel's sign at the medial ankle — reproduction of the burning symptoms by tapping over the tarsal tunnel — is a reliable clinical finding. Electrodiagnostic testing provides objective confirmation of tibial nerve compression when the diagnosis is uncertain.

Dr. Gunter evaluates suspected tarsal tunnel syndrome with careful clinical examination, Tinel's testing, assessment of the foot's structural mechanics, and electrodiagnostic referral when indicated — arriving at an accurate diagnosis before recommending a management approach.