Tarsal Tunnel Syndrome
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Tarsal tunnel syndrome is a compression neuropathy of the posterior tibial nerve as it passes behind the medial malleolus and under the flexor retinaculum (laciniate ligament) in the medial ankle, a region commonly known as “the tarsal tunnel.”
- Tarsal tunnel syndrome can occur during pregnancy, typically secondary to local compression caused by fluid retention and volume changes.
- Care usually is supportive until after delivery because many cases resolve after pregnancy.
- Women are slightly more affected than men (56%).
- Individuals in all postpubescent ages can be affected.
- Several authors have associated tarsal tunnel syndrome with certain occupations and activities, especially those that involve repetitive weight bearing on the foot and ankle, like jogging (1) or dancing (2).
- Other possible risk factors include (3):
- Systemic inflammatory arthritis
- Connective tissue disorders
- Heel varus or valgus
- Tarsal tunnel syndrome is caused by compression of the tibial nerve within the tarsal tunnel, resulting in decreased blood flow and ischemic damage.
- Increased pressure in the confined space of the tarsal tunnel is caused by a variety of mechanisms, both mechanical and biochemical, all of which result in increased pressure on the posterior tibial nerve.
- Chronic compression can destroy endoneurial microvasculature, leading to edema and eventually fibrosis and demyelination (4).
- The specific cause is identifiable in only 60–80% of patients (5); causes can be grouped into 3 categories: Trauma, space-occupying lesion, and deformity.
- Most common causes include (5):
- Hindfoot varus or valgus
- Fibrosis of the perineurium
- Other causes of compression include:
- Osseous prominences
- Inflammatory synovitis
- Pigmented villonodular synovitis
- Tarsal coalition
- Accessory musculature
- In patients with a systemic disease such as diabetes, “double-crush” syndrome should be considered; this refers to the development of a 2nd compression along the same nerve at a site of anatomic narrowing in patients with previous proximal nerve damage (3).