(Ankle Nerve Disorder)
By: Peter Fuller
What is it?
Etiology: Tarsal Tunnel Syndrome is caused by the entrapment and compression of the posterior Tibial nerve and its branches under the Flexor Retinaculum in the distal portion of the posterior compartment of the leg. Causes of nerve entrapment of can range from trauma (sprains, strains and fractures) to participation in repetitive or strenuous activities like running
and jogging. The prevalence and incidence of Tarsal Tunnel Syndrome (AKA. “TTS”) is unknown in the literature, but appears to be high in the female population and in the population of runners.
Tarsal tunnel syndrome is caused by the entrapment of the Tibial nerve. The Tibial nerve follows a curving route down the back of the leg to the ankle, where it turns and curls below the inside of the ankle. There are four compartments in this region. In three of them, muscles are routed from the leg to the foot. In the fourth, the Tibial nerve and the posterior Tibial vein and artery are surrounded by muscles.
Along the top of these structures lies the Laciniate ligament, which forms the roof of the four compartments. There is little room for expansion if any of these structures becomes enlarged or if a foreign object intrudes into the area. If anything impinges on the space occupied by the Tibial nerve (i.e., the Tarsal Tunnel), entrapment occurs.
The most common cause of Tarsal Tunnel Syndrome is trauma with heel deformities, varicosities and fibrosis affecting the region as well. Hyper-pronation of the foot may be a contributing factor in the development of tarsal tunnel syndrome. Many other conditions may affect the foot and present with similar symptoms, such as Plantar Fasciitis, Hallux Valgus, Posterior Tibial Tendonitis, Diabetic Neuropathy and Metatarsalgia.
Review of anatomy
The Tarsal Tunnel is considered a fibro-osseous tunnel on the medial ankle that starts just proximal to the medial malleolus and extends into the medial foot. The floor of the tunnel is made up of the medial aspects of the talus and calcaneus. The roof of the tunnel is bound by the fibrous Flexor Retinaculum. The retinaculum extends from the Medial Malleolus into the Crural fascia, with its distal portion typically being stronger than the proximal portion. Like the Carpal Tunnel at the wrist, the Tarsal Tunnel too has many structures passing through it. They include the Tibial nerve, Posterior Tibial artery and vein, and the deep flexors from the posterior compartment of the leg (Tibialis posterior, Flexor Digitorum Longus and Flexor Hallucis Longus). At the posterior aspect of the medial malleolus the Tibial nerve can be found between the tendons of the Flexor Digitorum Longus and the Flexor Hallucis Longus with the Posterior Tibial artery.
Typically inside the Tarsal Tunnel, just behind the Medial Malleolus, the Tibial nerve and Posterior Tibial artery will give off their terminal branches. The Tibial nerve gives rise to the medial and lateral plantar nerves and the medial calcaneal nerve. Medial calcaneal nerve may also arise from the lateral plantar nerve. They lie deep to the fascia of the Abductor Hallucis muscle as they descend toward the medial foot. These nerves supply sensory and motor innervation to the bottom of the foot and play a role in the distribution of symptoms related to tarsal tunnel syndrome. The posterior Tibial artery gives rise to medial and lateral plantar arteries and branches going to the Calcaneus.
The literature shows support for stretching and strengthening the posterior Tibial muscles and short flexors of the foot, corticosteroid injections, compression bandaging of the ankle and foot orthotics.
Tarsal tunnel syndrome symptoms are typically felt on the inside of the foot with symptoms radiating to the toes in some cases. Others may have pain on the whole bottom of the foot or radiate up into the posterior aspect of the leg. It may appear suddenly or as a result of an accumulation of injuries or abnormal postures or deformities of the foot. It is important to seek a proper evaluation of leg, heel or foot pain to determine the cause of the problem and to start the proper treatment program for the condition.
- Reduce pain and inflammation and tissue stress
- Restore muscle strength and flexibility
- Normalize strength, flexibility, and restore lower extremity functional mobility
Intervention Approaches / Strategies
- Therapeutic Exercise
- Calf stretching exercises
- Nerve mobility exercises
- Posterior Tibialis strengthening exercise
- Posterior Tibialis strengthening exercise in weight bearing
- Manual Therapy
- Soft tissue mobilization to fascia of Mayofascial tissues suspected of creating the entrapment
- Neural mobilization
Manual therapy modalities may be used to decrease inflammation and pain. Therapeutic exercise will increase strength and flexibility of the foot and ankle and manual therapy will address soft tissue and joint limitations.
If conservative treatment measures are unsuccessful, surgical treatment may be necessary.
Issue # 106 (Nov/Dec 2003) pp. 102-107
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