What is it?
Similar to carpal tunnel syndrome, it is a compression neuropathy of the posterior tibial nerve and its branches passing from the back of the leg along the medial malleolus (the interior side of the ankle) to the plantar foot. The nerve travels in a canal formed by the flexor retinaculum to the underside of the foot and splits into lateral, medial, and medial calcaneal (heel) branches. These branches form their own tunnels next to the tarsal tunnel and can also be the reason for the pain and discomfort. The causes are numerous and include: trauma, fractures, dislocation of ankle and rear foot, or sprain; basically anything that would cause compression of the nerve.
What are the symptoms?
The patient usually presents with sharp pain and numbness that radiates from the medial ankle down to the toes. There may also be burning and tingling at the heel that may occur at rest but become worse on standing or walking. The patient’s gait (how they walk) may become abnormal as they have a limp to ease the pain. Unfortunately because of the similarity in symptoms, the disorder could be mistaken with plantar fasciitis.
How is it treated?
Diagnosis of tarsal tunnel syndrome can be diagnosed with a positive Tinel’s sign. The area over the nerve is tapped along its distribution, which should create a tingling sensation. The most conservative treatment is to use an orthotic or device to keep the foot in an inverted position. Corticosteroid injections would also help with swelling and irritation of the nerve. In the end, the patient may need surgical intervention that involves a small incision to release the flexor retinaculum, which gives the nerve more space along its path to the plantar foot.