The tarsal tunnel is an anatomical location on the inside part of your ankle. This area of your foot is comprised of the flexor retinaculum, or thickened fascia, which forms the roof that holds an artery, vein, nerve, and flexor tendons against the inside portion of your ankle. The nerve that runs in the tarsal tunnel is called the posterior tibial nerve. When this nerve is injured, this causes what is known as tarsal tunnel syndrome. This can be a very painful condition affecting runners, due to compression of the posterior tibial nerve.
Symptoms:
Pain, burning, tingling and numbness are all possible symptoms of tarsal tunnel syndrome. While symptoms most commonly occur along the inside of the ankle and bottom of the foot, some patients also describe burning on the top of the foot due to nerve irritation. You will usually experience these symptoms on the inside part of your ankle, but since this nerve divides into two major nerves on the bottom part of your foot, you may also experience some of these symptoms there as well. Running and exercise will typically aggravate your symptoms. Most runners describe the pain as being worse after starting a new work-out regime or secondary to overuse.
Causes:
Abnormal biomechanics, such as a flat foot due to hyper-pronation, is a leading cause of tarsal tunnel syndrome: pronation causes a change in shape of the tunnel which compresses the nerve. Similarly, rapid weight gains can flatten out your arch which increases strain and compression placed on the posterior tibial nerve leading to tarsal tunnel symptoms. This mechanism is commonly seen with flat feet in pregnancy, where changes in weight and ligament laxity can alter foot structure and increase nerve compression. Traumatic injuries to the tarsal tunnel including ankle sprains, fractures, and/or previous ankle surgery can all cause impingement on the posterior tibial nerve secondary to swelling of soft tissues.
Diagnosis:
Evaluation of a patient’s history as well as a physical exam can point to this pathology as being the cause of pain to the inside of the ankle. EMG and Nerve Conduction Studies are sometimes ordered to test the functionality of your nerves. X-ray, ultrasound, or MRI may also be indicated for diagnosis.
Treatment:
Rest is considered the easiest and most obvious treatment option for tarsal tunnel syndrome. But what if you are training for a race a need to get back on the road? Discuss with your podiatrist other options for care, which may include:
- Anti-inflammatory medication
- Laser treatment
- Orthotics to control abnormal biomechanical forces
- Injections
If these symptoms are impacting your runs, please give us a call.