Tarsal Tunnel Syndrome is a compressive neuropathy of the tibial nerve within the fibro-osseous tunnel posterior and inferior to the medial malleolus (beneath the flexor retinaculum).
Tarsal Tunnel Anatomy
- Tarsal tunnel borders are as following:
- The roof of tunnel is formed by Flexor retinaculum (laciniate ligament).
- The ground of the tunnel is formed by talus and calcaneus bone.
- Inferiorly: abductor hallucis tendon.
- anteriorly: the medial malleolus.
- Tarsal tunnel includes the following:
- tibialis posterior tendon.
- Flexor hallucis longus tendon.
- Flexor digitorum longus tendon.
- Posterior tibial artery, the venae comitantes.
- Flexor retinaculum (laciniate ligament) is an unyielding fibrous roof extends from the medial malleolus posteriorly and inferiorly to the medial side of the tuberosity of the calcaneus and is 2.5 to 3.0 cm wide with indistinct borders. Its proximal border is continuous with the investing deep fascia of the calf, and distally its anterior margin is continuous with the deep fascia of the medial part of the sole.
- Engorged or varicose vessels.
- synovial or ganglion cysts.
- Pigmented villo-nodular synovitis.
- Nerve sheath tumors.
- Fracture of the sustentaculum tali or medial tubercle of the posterior process of the talus.
- Middle facet tarsal coalition.
- Accessory muscles.
- Inflammatory edema: as in systemic diseases such as diabetes mellitus, RA, and ankylosing spondylitis may have an indirect effect by causing inflammatory edema.
- A fixed valgus hindfoot can predispose to chronic traction neuropathy of the posterior tibial nerve or one of its branches, resemble tarsal tunnel syndrome.
Symptoms and signs:
- Symptoms of tarsal tunnel syndrome may be vague and misleading.
- Include a burning sensation on the plantar surface of the foot and medial ankle and occasional sharp pains or paresthesia.
- Prolonged standing, walking, or running can exacerbate the symptoms.
- Symptoms may increased at night, by exercise or rest, or by elevating or lowering the extremity.
- Tinel’s sign is positive over tibial nerve.
- The dorsiflexion-eversion is a provocative maneuver that produces the symptoms.
- Sensory examination is usually unpredictable:
- Sensory abnormalities or differences in temperature, sweating pattern, and skin abnormalities compared to the opposite foot.
- Dryness and scaliness of the skin may be present over only the medial or only the lateral plantar nerve distribution.
- Assess hindfoot alignment—pes planus may cause increased tension on the nerve.
- Atrophy of the abductor hallucis or abductor digiti minimi or both (often a difficult finding to detect).
- Electrodiagnostic studies.
- Electromyography (EMG) abnormalities are less sensitive.
- MRI may identify the presence of a mass occupying lesion.
- First line of treatment.
- 6 to 12 weeks of ankle immobilization in a night splint.
- Medications such as NSAIDs, vitamin B6, and tricyclic antidepressants.
- Physical therapy may include stretching, massage, desensitization, and iontophoresis.
- Orthoses to correct hindfoot valgus play an important role as well.
- Failed of nonoperative treatment (for 3 to 6 months)
- Space-occupying lesion.
- positive EMG.
- Reproducible physical findings.
- Longitudinal incision made over the course of the tibial nerve; curves distally behind medial malleolus to the abductor musculature.
- The nerve is identified proximally, and the proximal investing fascia and flexor retinaculum are released.
- Care must be taken to release the superficial and deep fascia of the abductor hallucis muscle.
- Endoscopic tarsal tunnel release is not recommended.
Anterior Tarsal Tunnel Syndrome
- Anterior Tarsal Tunnel Syndrome is a compressive neuropathy of the deep peroneal nerve in the fibro-osseous tunnel formed by the inferior extensor retinaculum.
Causes of Compression Anterior Tarsal Tunnel Syndrome
- Tightly laced shoes.
- Anterior osteophytes at the tibiotalar and talo navicular articulations
- A bony prominence associated with pes cavus deformity or fracture.
- Ganglion cysts.
- Tendinitis of the extensor digitorum longus, extensor hallux longus, or tibialis anterior.
- Burning pain and paresthesias along the medial second toe, lateral hallux, and first web space, or even vague dorsal foot pain.
- Symptoms are often worse at night as the ankle assumes a plantar-flexed posture, and with shallow, laced shoes.
- Decreased two-point discrimination.
- Positive Tinel sign along course of the deep peroneal nerve.
- Pain may be worse with plantar flexion of ankle as the nerve is stretched.
- First line of treatment.
- Treatments include:
- Night splints.
- Non-steroidal anti-inflammatory drugs (NSAIDs) .
- Corticosteroid injections.
- Shoe tongue padding, and footwear with loose lacing or alternative lacing techniques are the conservative approaches.
- Surgical release:
- Incising the inferior extensor retinaculum.
- Excising bone spurs
- Carefully repairing the bony capsule to avoid exposing the nerve to bleeding bone while protecting the dorsalis pedis artery.