- The tarsal tunnel is a narrow space posterior to the medial malleolus. The tunnel is covered with the flexor retinaculum that protects and maintains the structures contained within.
- Tarsal tunnel syndrome is a compression or squeezing on the posterior tibial nerve that produces symptoms anywhere along the path of the nerve.
- A person with flat/pronated feet is at risk for developing tarsal tunnel syndrome because the outward tilting of the heel that occurs with “fallen” arches can produce strain and compression on the nerve.
- An enlarged or abnormal structure that occupies space within the tunnel can compress the nerve. Some examples include a varicose vein, ganglion cyst, swollen tendon, and arthritic bone spur.
- An injury, such as an ankle sprain, may produce inflammation and swelling in or near the tunnel, resulting in compression of the nerve.
- Systemic diseases such as arthritis can cause swelling, thus compressing the nerve.
- Tingling, burning, or a sensation similar to an electrical shock inside of the ankle and/or on the bottom of the foot.
- Numbness inside of the ankle and/or on the bottom of the foot.
- Pain (including shooting pain) inside of the ankle and/or on the bottom of the foot.
- Symptoms may extend to the heel, arch, toes, and even the calf.
- Aggravated by overuse of the foot, such as in prolonged standing, walking, exercising, or beginning a new exercise program.
Tests and Imaging
- It is important to rule out L4-S3 spinal nerve compression.
- Direct pressure or tapping on the nerve reproduces patient’s symptoms (Tinel’s sign)
- Weightbearing x-rays and ultrasound of the foot should be assessed to review for any obvious pathology in the hind foot.
- A CT scan or MRI is sometimes indicated to rule out a mass, which may be irritating the nerve.
- Advise weight loss to decrease the repetitive forces through this area of the foot.
- Advise activity modification to limit the amount of standing and walking and thereby the amount of repetitive injury to this area.
- Corticosteroid injections may help to decrease the swelling around the nerve in the short and intermediate term.
- Podiatry for footwear advice, orthoses, strapping.
- Orthopaedic foot surgeon for possible release of flexor retinaculum.