Tarsal tunnel syndrome (TTS), also known as posterior tibial neuralgia, is a compression neuropathy and painful foot condition in which the tibial nerve is compressed as it travels through the tarsal tunnel. This tunnel is found along the inner leg behind the medial malleolus (bump on the inside of the ankle). The posterior tibial artery, tibial nerve, and tendons of the tibialis posterior, flexor digitorum longus, and flexor hallucis longus muscles travel in a bundle through the tarsal tunnel. Inside the tunnel, the nerve splits into three different segments. One nerve (calcaneal) continues to the heel, the other two (medial and lateral plantar nerves) continue on to the bottom of the foot. The tarsal tunnel is delineated by bone on the inside and the flexor retinaculum on the outside.
- Pain and tingling in and around ankles and sometimes the toes
- Swelling of the feet
- Painful burning, tingling, or numb sensations in the lower legs. Pain worsens and spreads after standing for long periods; pain is worse with activity and is relieved by rest.
- Electric shock sensations
- Pain radiating up into the leg, and down into the arch, heel, and toes
- Hot and cold sensations in the feet
- A feeling as though the feet do not have enough padding
- Pain while operating automobiles
- Pain along the Posterior Tibial nerve path
- Burning sensation on the bottom of foot that radiates upward reaching the knee
- “Pins and needles”-type feeling and increased sensation on the feet
- A positive Tinel’s sign
Tinel’s sign is a tingling electric shock sensation that occurs when you tap over an affected nerve. The sensation usually travels into the foot but can also travel up the inner leg as well.
Diabetes makes the peripheral nerve susceptible to nerve compression, as part of the double crush hypothesis. In contrast to carpal tunnel syndrome due to one tunnel at the wrist for the median nerve, there are four tunnels in the medial ankle for tarsal tunnels syndrome. If there is a positive Tinel sign when you tap over the inside of the ankle, such that tingling is felt into the foot, then there is an 80% chance that decompressing the tarsal tunnel will relieve the symptoms of pain and numbness in a diabetic with tarsal tunnels syndrome.
Treatments typically include rest, manipulation, strengthening of tibialis anterior, tibialis posterior, peroneus and short toe flexors, casting with a walker boot, corticosteroid and anesthetic injections, hot wax baths, wrapping, compression hose, and orthotics. Medications may include various anti-inflammatories such as Anaprox, or other medications such as Ultracet, Neurontin and Lyrica. Lidocaine patches are also a treatment that helps some patients.
Many patients report good results. Some, however, experience no improvement or a worsening of symptoms. In the Pfeiffer article (Los Angeles, 1996), fewer than 50% of the patients reported improvement, and there was a 13% complication rate. This is a staggering percentage of complications for what is a fairly superficial and minor surgical procedure.