Tarsal tunnel syndrome is a tunnel syndrome characterized by compression of the posterior tibial nerve and/or its distal terminal branches by the internal annular ligament.
The posterior tibial nerve gives, in the retro-malleolar region, the internal calcaneal nerve directed towards the greater tuberosity of the calcaneus and ensures plantar sensitivity of the heel.
The nerve then divides upon entering the submalleolar portion of the tarsal tunnel into medial and lateral pedicles. These two lateral and medial plantar pedicles will engage under the plant, crossed at this point by the abductor of the big toe and its fibrous arch. This aponeurotic arch of the abductor hallucis represents the key to surgical release of the tarsal tunnel. There are multiple identifiable causes: compressive by a local tumor or post-traumatic thickening, inflammatory in the context of tenosynovitis, by elongations, etc. but in more than 25% the lesion is idiopathic.
Anatomical diagram of the tarsal tunnel:
- Internal or medial malleolus
- Posterior tibial nerve
- Toe flexor retinaculum
- Medial calcaneal nerve
- Lateral plantar nerve
- Medial plantar nerve
- Hallux abductor muscle
Local pain at the level of the medial malleolus with radiation towards the medial and/or plantar aspects of the heel, towards the arch of the plantar and sometimes proximally towards the medial part of the leg, rarely higher.
Burning or cramping pain, increased by tension, pressure or tapping (Tinel) of the nerve in the retro- and infra-malleolar regions, of the sole of the foot and toes.
Dysesthesias: cardboard skin, tension and pressure, especially localized in the innervation territory of the medial plantar nerve; the medial two thirds of the arch of the foot, the hallux and the first three toes.
Sometimes vasomotor disorders with disturbance of sweating, edema of the medial malleolar region, trophic skin disorders in the innervation territory of the tibial nerve. Rarely motor or vascular disorders.
Symptomatology “in attacks”, especially at night or after a long period of standing, a long walk or run. Sometimes bilateral symptoms, especially in cases of static anomalies.
Talalgia or plantar fasciitis symptoms increased by valgus of the calcaneus, dorsiflexion of the ankle, abduction with pronation of the midtarsus and extension of the toes. Calcaneus varus can, following relaxation of the retinaculum of the flexor muscles, relieve pain.
Territory of cutaneous innervation of the posterior tibial nerve:
- Medial plantar nerve
- Lateral plantar nerve
- Calcaneal nerve
- Functional overwork:
- Prolonged standing position,
- climbing ladders or stairs,
- sports (jumping, classical dance, cycling, rackets, ball).
- Static elongation: flat foot, valgus position of the heel, excessive pronation of the midtarsus, hyper- or hypomobility of the foot.
- Traumatic elongation: sprained ankle and everted foot for example.
- A compression:
- Tenosynovitis of the flexor digitorum longus muscles or the tibialis posterior muscle,
- Fibrous thickening of the tendon sheaths and retinaculum of the toe flexor muscles,
- Posttraumatic exostosis (valgus sprain, medial malleolar fracture, fracture of the talus or calcaneus),
- Ganglion cyst, neuroma or lipoma,
- Any factor reducing the diameter of the tarsal canal.
- Edema, hematoma or post-traumatic scar. A hematoma caused by a tear in the medial head of the gastrocnemius muscle.
- Hypertrophy of the abductor hallucis muscle or the presence of supernumerary muscles. A congenital narrowing of the groove where the tibial nerve passes.
- A talocrural dislocation,
- Osteoarthritis of the ankle,
- Arthritis of the ankle.
- Idiopathic (25%).
- Myofascial syndrome of the flexor digitorum longus, tibialis posterior and abductor hallucis longus muscles.
- Tenosynovitis of the posterior tibial, flexor digitorum longus and hallux muscles.
- Calcaneal tendon tendinopathy.
- Posterior compartment syndrome of the leg.
- Myofascial syndrome of the posterior leg muscles
- Stress fracture of the calcaneus.
- Atrophy of the heel fat pad.
- Plantar fasciitis or rupture of the plantar fascia.
- Haglund’s disease or Sever’s disease.
- Morton’s neuroma.
- Talocrural or subtalar joint dysfunction
- Pseudo Tinel sign: triggering of neuropathic pain on medial submalleolar percussion.
- Reduction in foot symptoms in intermediate flexion, varus and knee flexion.
- Worsening of symptoms with the foot in maximum flexion, valgus and knee extension.
In search of a non-idiopathic etiology. (See etiology chapter).
- Treatment of the cause. (See etiologies)
- Physiotherapy and/or osteopathy. Work on the opening of the tarsal canal, the abductor hallucis. Neurodynamic work.
- Podiatry, posturology. making insoles allowing opening of the tarsal tunnel
- Anti-inflammatory treatment per. (NSAIDs, corticosteroids)
- Infiltration. Corticosteroid injection +/- lidocaine
- Surgery. Release of the tarsal tunnel.
- Treatment of neuropathic pain.