Tarsal Tunnel Syndrome

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Basics

Description

Tarsal tunnel syndrome refers to a compression or entrapment neuropathy of the posterior tibial nerve as it passes through a fibro-osseous tunnel (tarsal tunnel) located posterior and inferior to the medial malleolus and deep to the flexor retinaculum (laciniate ligament) in the medial ankle.

Epidemiology

  • Women are slightly more affected than men (56%).
  • All postpubescent ages are affected.

Etiology and Pathophysiology

  • Contents within the tarsal tunnel from the anterior medial to the posterior lateral side include the following: the posterior tibial tendon, the flexor digitorum longus tendon, the posterior tibial artery and veins, the posterior tibial nerve, and the flexor hallucis tendon.
  • The posterior tibial nerve passes through the tarsal tunnel, which is formed by three osseus structures—sustentaculum tali, medial calcaneus, and medial malleolus—covered by the laciniate ligament.
  • Compression of the posterior tibial nerve within the tarsal tunnel results in decreased blood flow, ischemic damage, and resultant symptoms (1).
  • Chronic compression can destroy endoneurial microvasculature, leading to edema and (eventually) fibrosis and demyelination (2).
  • Increased pressure in the tarsal tunnel is caused by a variety of mechanical and biochemical mechanisms. The specific cause for compression is identifiable in only 60–80% of cases (1).
  • Three general categories: trauma, space-occupying lesions, deformity (1)
    • Trauma including displaced fractures, deltoid ligament sprains, or tenosynovitis
    • Varicosities
    • Hindfoot varus or valgus
    • Fibrosis of the perineurium
  • Other causes:
    • Osseous prominences; osteophytes
    • Ganglia; lipoma; neurilemmoma
    • Inflammatory synovitis
    • Pigmented villonodular synovitis
    • Tarsal coalition
    • Accessory musculature
  • In patients with systemic disease (e.g., diabetes), the “double crush” syndrome refers to the development of a second compression along the same nerve at a site of anatomic narrowing in patients with previous proximal nerve damage (3).

Risk Factors

  • Tarsal tunnel syndrome is associated with certain occupations and activities involving repetitive and prolonged weight-bearing on the foot and ankle (walking, running, dancing).
  • Other possible risk factors include (4):
    • Diabetes
    • Systemic inflammatory arthritis
    • Connective tissue disorders
    • Obesity
    • Varicosities
    • Heel varus or valgus
    • Bifurcation of the posterior tibial nerve into medial and lateral plantar nerves proximal to the tarsal tunnel

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Basics

Description

Tarsal tunnel syndrome refers to a compression or entrapment neuropathy of the posterior tibial nerve as it passes through a fibro-osseous tunnel (tarsal tunnel) located posterior and inferior to the medial malleolus and deep to the flexor retinaculum (laciniate ligament) in the medial ankle.

Epidemiology

  • Women are slightly more affected than men (56%).
  • All postpubescent ages are affected.

Etiology and Pathophysiology

  • Contents within the tarsal tunnel from the anterior medial to the posterior lateral side include the following: the posterior tibial tendon, the flexor digitorum longus tendon, the posterior tibial artery and veins, the posterior tibial nerve, and the flexor hallucis tendon.
  • The posterior tibial nerve passes through the tarsal tunnel, which is formed by three osseus structures—sustentaculum tali, medial calcaneus, and medial malleolus—covered by the laciniate ligament.
  • Compression of the posterior tibial nerve within the tarsal tunnel results in decreased blood flow, ischemic damage, and resultant symptoms (1).
  • Chronic compression can destroy endoneurial microvasculature, leading to edema and (eventually) fibrosis and demyelination (2).
  • Increased pressure in the tarsal tunnel is caused by a variety of mechanical and biochemical mechanisms. The specific cause for compression is identifiable in only 60–80% of cases (1).
  • Three general categories: trauma, space-occupying lesions, deformity (1)
    • Trauma including displaced fractures, deltoid ligament sprains, or tenosynovitis
    • Varicosities
    • Hindfoot varus or valgus
    • Fibrosis of the perineurium
  • Other causes:
    • Osseous prominences; osteophytes
    • Ganglia; lipoma; neurilemmoma
    • Inflammatory synovitis
    • Pigmented villonodular synovitis
    • Tarsal coalition
    • Accessory musculature
  • In patients with systemic disease (e.g., diabetes), the “double crush” syndrome refers to the development of a second compression along the same nerve at a site of anatomic narrowing in patients with previous proximal nerve damage (3).

Risk Factors

  • Tarsal tunnel syndrome is associated with certain occupations and activities involving repetitive and prolonged weight-bearing on the foot and ankle (walking, running, dancing).
  • Other possible risk factors include (4):
    • Diabetes
    • Systemic inflammatory arthritis
    • Connective tissue disorders
    • Obesity
    • Varicosities
    • Heel varus or valgus
    • Bifurcation of the posterior tibial nerve into medial and lateral plantar nerves proximal to the tarsal tunnel

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