Definition:
Tarsal Tunnel Syndrome is due to compression of a nerve called the Posterior Tibial Nerve.The nerve passes into the foot from around the inside of the ankle just below the ankle bone. Just beyond this point, the nerve enters the foot by passing between a muscle and a bone in the foot. This area is called the Tarsal Tunnel. The Posterior Tibial Nerve is the largest nerve that enters the foot. At the level of the ankle, the nerve branches out like the branches of a tree as it goes out toward the toes. This nerve supplies most of the sensation to the bottom of the foot and the muscles in the bottom of the foot. When pressure is placed on this nerve, a burning or numbness will be experienced on the bottom of the foot. The area of the bottom of the foot that is affected can be variable. Most commonly, it affects the outside portion of the bottom of the foot. It can also affect the toes, mimicking a neuroma. The most common cause of Tarsal Tunnel Syndrome is a flat foot or a foot in which the arch flattens excessively while walking. Over time, this causes the nerve to stretch or become compressed in the area of the tarsal tunnel. The condition is slowly progressive and occurs more commonly after 30 – 40 years of age. Other causes of Tarsal Tunnel Syndrome are the formation of soft tissue masses such as ganglions, fibromas, or lipomas that may occur in the Tarsal Tunnel and cause compression of the nerve. Also, small varicose veins may form around the nerve that can also cause compression of the nerve.


Flattening of the arch of the foot is due to an abnormal function of a joint complex called the Subtalar Joint. This joint complex is located just below the ankle joint. When this joint allows the foot to flatten excessively, the foot becomes over pronated. Pronation is a normal movement of the foot, but when it occurs too much of the time, it causes several different problems to occur in the foot, one of them being Tarsal Tunnel Syndrome.

Symptoms:
Pain, numbness, burning and electrical sensations may occur along the course of the nerve, which includes the inside of the ankle, heel, arch and bottom of foot. Symptoms are usually worsened with increased activity such as walking or exercise. Prolonged standing in one place may also be an aggravating factor.

Cause:
There are a variety of factors that may cause tarsal tunnel syndrome. These may include repetitive stress with activities, flat feet, and excess weight. Additionally, any lesion that occupies space within the tarsal tunnel region may cause pressure on the nerve and subsequent symptoms. Examples include tendinitis, hematoma, tumor, varicose veins and lower extremity edema.

Diagnosis:
The diagnosis of tarsal tunnel is made primarily by the clinic experience of a podiatric foot and ankle surgeon. A Tinel's sign (radiating pain upon tapping the nerve) may be elicited. Temporary relief may be obtained with a diagnostic local anesthetic injection. Electrodiagnostic studies such as nerve conduction velocity (EMG/NCV) testing may also prove useful. Magnetic resonance imaging (MRI) may also help to evaluate for local pathology or space occupying lesions.

Treatment:
Conservative treatment for tarsal tunnel syndrome includes the use of nonsteroidal anti-inflammatories, ice, physical therapy, orthotic devices, steroid injections and cast immobilization.

When conservative treatment is unsuccessful, surgical intervention is performed by the podiatric foot and ankle surgeon. The surgery involves release of the tibial nerve and its branches from the surrounding tight structures along with incision of the laciniate ligament, a structure that forms a roof over the nerve bundle.

Postoperatively, a period of immobilization followed by protected weightbearing and physical therapy may be prescribed. Complications of surgery may include continued nerve pain, tingling and numbness and the possibility of infection.