Tarsal Tunnel Syndrome

A view of the posterior-medial ankle and tarsal tunnel (flexor retinaculum faded)

Tarsal Tunnel Syndrome (TTS) is a compression neuropathy (trapped nerve) of the Tibial Nerve or one of its branches as it passes behind the Medial Malleolus and under the Flexor Retinaculum in a space called “the Tarsal Tunnel”. The Tarsal Tunnel as a space created between the Medial Malleolus of the Tibia, Talus, Calcaneus and Flexor Retinaculum. This space contains the Posterior Tibial Neurovascular Bundle (which includes the Posterior Tibial Artery, Vein and Nerve) and the tendons of Flexor Hallucis Longus, Flexor Digitorum Longus and Tibialis Posterior muscles.

People with TTS will present with pain around the Tarsal Tunnel, Medial Malleolus and/or plantar aspect of the foot (sole). There may also be paraesthesia (“pins and needles”), burning sensations, numbness, and shooting pains (all indicating neurogenic pain – nerve pain). These symptoms tend to be worse for activity and standing. Burning sensations at night can affect sleep. TTS is usually unilateral (one side only). Symptoms may come and go in the early stages, but can become permanent as the muscles ennervated by the affected nerves being to atrophy (wither and weaken). The Tibial Nerve divides into the Medial and Lateral Plantar Nerves as it passes through the Tarsal Tunnel, meaning both or either, and the tissues they ennervate, can be affected. The Calcaneal Branch of the Tibial Nerve may also be affected in some cases, as it may divide from the Tibial Nerve at the Tarsal Tunnel in some people and above it in others.

TTS can be idiopathic in many cases, which means that no causes could be found. However, there are several underlying issues that can lead to TTS, including:

  1. Biomechanical abnormalities leading to excessive foot pronation. As the heel everts, and the subtalar joint pronates, moving the talus and navicular medially (called “navicular drift”), this can lead to compression of the Tibial Nerve within the Tarsal Tunnel.
  2. Space-occupying masses such as ganglion cysts, swollen tendons, osteophytes, or a varicose vein, can take up space within the Tarsal Tunnel, leading to compression of the nerve.
  3. An injury, such as an ankle sprain, fracture or dislocation in the area can lead to inflammation and swelling in or near the Tarsal Tunnel.
  4. Diseases such as Rheumatoid Arthritis, Osteoarthritis, and Gout can cause swelling and compression of the nerve.

Diagnosis is made by taking a history of the condition and by examination. Imaging does not rule out TTS. X-Ray imaging can rule out changes to the bone being a cause (eg. fractures; osteophytes formed within the Tarsal Tunnel) and MRI can rule out if space-occupying masses such as ganglion cysts are present in the Tarsal Tunnel. There may be tenderness or “Tinel’s Sign” on palpation of the nerve as it passes under the Flexor Retinaculum. Ankle dorsiflexion and eversion of the foot can also reproduce symptoms. In some cases of TTS, these tests will be negative despite the person having the condition.

Conservative treatment in podiatry practice may include any of the following:

  1. Rest.
  2. NSAIDs (ibuprofen, paracetamol) as and when required.
  3. Orthoses to correct underlying biomechanical issues if these are present .
  4. The foot may need to be immobilised in more severe cases.
  5. Acupuncture to help with pain and inflammation, and to facilitate healing.
  6. Therapeutic soft tissue exercises can help address weak, tight, or imbalanced muscles that may be causing or contributing to this condition.
  7. Foot Mobilisation Therapy: frees restrictions in the joints, strengthens muscles around the joint, reduces pain.
  8. Therapeutic strapping.
  9. Corticosteroid injections.

If conservative methods are ineffective, then surgery may be necessary.

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