Tarsal Tunnel Syndrome

Description :1,2

Tarsal tunnel syndrome, commonly referred to as tibial nerve dysfunction, is an uncommon peripheral neuropathy caused by damage to and/or compression of the posterior tibial nerve within the tarsal tunnel. The tarsal tunnel can be found slightly behind and just below the medial malleolus on the inside of the ankle. The tibial nerve supplies motor and sensory input to the muscles of the calf and foot. Several factors may contribute to the compromise of the tibial nerve such as bony prominences or soft-tissue masses such as varicose veins. Tarsal tunnel syndrome defines any entrapment of the posterior tibial nerve and its branches. This includes entrapment of the tibial nerve after the nerves passes deep to the flexor retinaculum. Tarsal tunnel is analogous to carpal tunnel syndrome of the wrist, but it is far less common.

Anatomy:3,4,5

The tarsal tunnel is formed by a thick band of fibrous tissue called the flexor retinaculum which extends posteriorly and distally to the medial malleolus. The flexor retinaculum is formed by the aponeurosis of the leg and is very dense. Any additional agents or inflammation within the tunnel will compress the contents of the tunnel such as the tibial nerve. Within the tarsal tunnel, between the calcaneous and the medial malleolus the posterior tibial nerve bisects into the medial and lateral plantar nerves.

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Boundaries

  • Roof
    • Flexor retinaculum
  • Back/Floor
    • Posterior talus and calcaneous
  • Side
    • Medial malleolus

Tunnel Contents

  • Muscles
    • Posterior tibialis, flexor digitorum longus, flexor hallicus longus
  • Nerve
    • Posterior tibial nerve that branches from the sciatic nerve (L4 - S3)
  • Vessels
    • Posterior tibial vein and posterior tibial artery

The pathway of the posterior tibial nerve is relevant to this pathology. After entering the lower leg between the medial and lateral heads of the gastrocnemius, the nerve resides in the deep posterior compartment between the posterior tibialis muscle and the flexor digitorum longus. As it travels down further into the lower leg, it lies between the flexor digitorum longus and the flexor hallucis longus muscles where it then enters the tarsal tunnel. After the tibial nerve bifurcates in the tarsal tunnel, the medial and lateral plantar nerves are formed.

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Medial Plantar Nerve

  • Sensation
    • Medial half of the foot
    • First 3 and 1/2 digits
  • Motor
    • Lumbricals
    • Abductor hallucis
    • Flexor digitorum brevis
    • Flexor hallucis brevis

Lateral Plantar Nerve

  • Sensory
    • Medial calcaneous
    • Lateral heel
  • Motor
    • Flexor digitorum brevis
    • Quadratus plantae
    • Abductor digiti minimi

Incidence/Prevalence:6

The incidence of tarsal tunnel syndrome is not well defined. Tarsal tunnel syndrome is listed as a "rare disease" by the Office of Rare Diseases (ORD) of the National Institutes of Health. This means that tarsal tunnel syndrome affects less than 200,000 people in the United States. The cause of tarsal tunnel syndrome can be identified in 60 - 80% of the cases. The incidence of tarsal tunnel syndrome in females is higher than males as well as in those who over-pronate or present with pes planus. There are many entrapment syndromes that may ensue in the distal lower limb and for this reason differential diagnosis through thorough subjective and objective examination is essential.

Clinical Presentation:7,8,9

Common symptoms typically seen in patients with tarsal tunnel syndrome may include any or all of the following:

  • sharp, shooting foot pain; commonly confused with plantar fasciitis or heel spurs
  • numbness on the plantar surface of the foot
  • radiation of pain/paresthesias along course of the nerve, posterior to the medial malleolus
  • pain at end range dorsiflexion and eversion
  • tingling or burning sensation

These symptoms may be felt in isolation, point specific on the medial ankle, or on the bottom of the foot. The symptoms may also be found extending to the heel, arch, toes, and lower leg. The location of the symptoms is somewhat dependent upon which branch of the posterior tibial nerve is most affected. For example, pain in the heel associated with weightbearing is indicative of the lateral plantar nerve while medial plantar nerve involvement causes pain in the medial arch radiating to the medial toes also associated with weightbearing. While the location of the symptoms may be somewhat variable, they are worse with weightbearing and relieved by rest.

Recently, the focus on the contributing factors to tarsal tunnel syndrome has focused on over-pronation also known as pes planus. Pes planus is due to the medial longitudinal arch of the foot not forming properly. The navicular and cuboid bones are closer to the ground or touching the ground during standing and walking which changes the pressure on the surfaces of the foot during standing and walking. The alteration in biomechanics of the lower foot increases traction on the tibial nerve leading to symptoms of tarsal tunnel syndrome. This is due to tension and not compression in the tarsal tunnel, and correction of the pronation through orthotic or taping is required if this is the cause of the tarsal tunnel syndrome symptoms.

Etiology:10

Tarsal tunnel syndrome can be associated with any form of external compression of the posterior tibial nerve within the tarsal tunnel. Compression may be caused by a cyst, traumatic soft tissue or bone injury with secondary inflammation, varicosities, tumors, or a congenitally narrow tarsal tunnel. Arterial or muscular variation of any kind in addition to nearby tendon pathology, tarsal coalition (abnormal fusion of one or more bones), hypertrophic sustentaculum tali, or arthritis can also contribute to compression of the posterior tibial nerve in the tarsal tunnel.

Anatomic Factors Tumor Trauma Inflammatory Factors Miscellaneous Factors
Septa Neuroma Fracture Rheumatoid arthritis Footwear
Areolar tissue Lipoma Contusions Ankylosing spondylitis Overuse syndromes
Vascular anomalies Cyst and ganglion Postsurgical adhesions Tenosynovitis Weight gain
Muscular variations Tendon tumors Sprains Fluid retention
Calcaneal valgus Laceration Pregnancy
Pes planus Post-traumatic edema and/or adhesions

Diagnostic and Special Tests:11,12,13,14,15

While there is not a gold standard clinical measure for the diagnosis of tarsal tunnel syndrome, patient history, reported history of pain, as well as physical examination to include diagnostic and special tests, can guide the clinician's thought process. The most widely used diagnostic and special tests for the diagnosis of tarsal tunnel syndrome are nerve conduction studies, Tinel’s test, the dorsiflexion-eversion test, and imaging through ultrasonography, CT, or MRI to assess soft tissue lesions and rule out compressive lesions and fracture. It is imperative that physical therapists and physicians be knowledgeable in the presentation of tarsal tunnel syndrome as it has been shown to be incorrectly diagnosed in 74% of cases.

Diagnostic Tests

Patel et al, found that nerve conduction studies (NCSs) were abnormal in a number of patients with suspected tarsal tunnel syndrome. While no sensitivity or specificity could be determined, sensory NCSs were more likely to have diagnostic significance than motor NSCs, with abnormal sensory conduction found in 96% of patients in one study. Other tests, as stated above, include, CT, MRI, and ultrasound imaging.

Special Tests

Tinel's sign involves lightly tapping the medial ankle over the course of the posterior tibial nerve as it passes through the tarsal tunnel. A positive sign is tingling in the distribution of the nerve due to the tapping. This test has 25-75% sensitivity and 70-90% specificity.

The dorsiflexion-eversion test is done by passively everting and dorsiflexing the ankle to end range of motion and maximally dorsiflexing the metatarsophalangeal joints (see picture below). This position is held for five to ten seconds. A reproduction of symptoms is a positive sign. This is due to compression placed on the tibial nerve as tension is applied in this position. Kinoshita et al, found this test to exacerbate symptoms in 82% of patients with suspected tarsal tunnel syndrome.

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Dorsiflexion-Eversion Test. Image from jbjs.org

Differential Diagnosis:16,17

Subjective history is essential in the diagnosis of tarsal tunnel syndrome as there are many other possible pathologies of the foot in all locations with symptomatology paralleling that of tarsal tunnel syndrome. For instance, differentiation between musculoskeletal overuse issues and nerve or vascular entrapment is essential as management for each will differ. Subjective history should involve obtaining the following information: mechanism of injury, location of pain, type of pain, changes in symptoms over time (getting worse/better), the type of shoes the patient wears, and if there is bruising or swelling present. These question will help guide the diagnostic process. Findings on the subjective examination to help guide the clinician toward the diagnosis of tarsal tunnel syndrome are complaints of tingling, burning, and numbness in the posterior heel and medial aspect of the foot with possible complaints of radiating symptoms to the distal sole and toes. Compared to other conditions of posterior heel pain, passive end range dorsiflexion and eversion on the objective aspect of the exam should reproduce the patient's complaint of tingling, numbness, or burning. Differtial diagnosis associated with these symptoms include plantar fasciitis, achilles tendonitis, and retrocalcaneal bursitis. The following section is a brief description of each condition to identify differences from the condition and tarsal tunnel syndrome.

  • Plantar fasciitis: results from repetitive use, increased tension, or excessive loading on the plantar fascia. Possible causes of plantar fascitis include pes planus, pes cavus, decrease subtalar joint mobility, and a tight achilles tendon. Subjective examination findings should include complaints of gradual heel pain which is worse on taking first steps in the morning or standing after prolonged sitting. There should be no complaints of burning, tingling, or numbness in a patient with plantar fasciitis. On objective examination, palpation will create tenderness at the medial calcaneal tuberosity and the plantar fascia itself. Passive stretching of the plantar fascia by dorsiflexing the toes will also create pain due to stretch on the plantar fascia.
  • Achilles tendonitis: is a condition with the main complaint of pain and swelling at the tendon location. During subjective examination, a history of having trouble with strenuous activities including jumping and running activities will be present. Increases in high-stress training programs or increase activity are often the mechanism of injury for achilles tendonitis. On objective examination, increased tenderness should be noted upon palpation of the insertion of the tendon into the calcaneus. Passive dorsiflexion should reproduce pain due to stretching of the tendon. Swelling may be noted in the area of the tendon.
  • Retrocalcaneal Bursitis: This bursa is located between the calcaneus and the achilles tendon. Inflammation of this bursa is usually caused by ill fitting foot wear. Objective findings will include redness, swelling in the location of the bursa, and tenderness on palpation of the bursa.

Common Causes of Heel Pain: History, Physical Examination Findings, and Treatment Options

Clinical Entity History Physical Examination Conservative Treatment
Plantar Fasciitis morning pain or pain on standing after prolonged sitting tenderness over calcaneus; increased pain with passive dorsiflexion of toes analgesics, stretching, exercise, orthotics, night splint
Achilles Tendonitis pain with running, jumping, or making quick turns pain and tenderness over insertion of Achilles tendon on calcaneus. Pain may increase with dorsiflexion Rest, analgesics, stretching and strengthening exercises
Retrocalcaneal Bursitis stiff posterior shoe edge pain and tenderness at posterior calcaneus analgesics, proper shoes with achilles notch and padding over posterior heel
Tarsal Tunnel Syndrome Pain or numbness in heel radiating to the sole or toes Reproduction of symptoms with percussion of tarsal tunnel or dorsiflexion and eversion of the foot analgesics, correcting foot posture with orthotics, stretching and strengthening

Treatment:18,19,20,21,22,23

Tarsal tunnel syndrome not complicated by muscle atrophy may be managed conservatively; however, if conservative treatment fails to relieve symptoms and allow the patient to return to normal levels of function, surgical treatment may be indicated.

Conservative Management

Conservative treatment for tarsal tunnel syndrome is most effective for tibial nerve compression that is a result of tenosynovitis or flexible foot deformities. If the entrapment is a result of a space occupying lesion then surgical treatment is usually appropriate. When conservative treatment is used it focuses around the different stages of healing. The primary goal of treatment in the acute stage of the disease is to decrease pain, inflammation, and tissue stress. During this stage, and throughout the rehabilitation process, many modalities will be used in order to achieve these goals including: ice, contrast baths, pulsated ultrasound, lidocane ointment, iontophoresis, and interferential current therapy.

The use of orthotics and taping can also be helpful in the acute phase. A University of California Berkeley Laboratory (UCBL) orthosis can be used to improve hindfoot alignment.

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Plantar arch taping can be used to reduce the amount of stress on the tissue.

A medial heel wedge, or heel seat, may be useful in removing traction from the tibial nerve by assisting in inverting the heel.

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Therapeutic exercises also play a large role in the early treatment of tarsal tunnel syndrome. Two of the major treatments done are calf stretching exercises and nerve mobility exercises. Calf stretches that are commonly done include two different forms of a wall stretch, one that focuses on the gastrocnemius (the first picture below) and one that focuses on the soleus (the second picture below).

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Images from sportspodiatry.co.uk

Tibial nerve glides are also done in order to encourage the nerve to move normally and reduce any tension or obstruction to movement that may be hindering its natural course.

Soft tissue mobilization should also be utilized over any areas in which entrapment has thought to have occurred.

In the sub-acute treatment phase you want to continue with the same course of treatment as before but add strengthening exercises that focus on the tibialis posterior.

Some basic tibialis posterior strengthening exercises include isometric eversion, isotonic eversion, isometric inversion, and isotonic inversion. These are show in the images below in the order mentioned in the sentence above.

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In the settled stage you want to continue with all the previously listed treatments as appropriate and add in posterior tibialis exercises in weight bearing. A good advanced exercise that is good for strengthening this muscle is the single legged heel raise with a twist at the top.

Surgical Management

Someone with tarsal tunnel syndrome usually undergoes surgery for the disorder when conservative treatment fails. Failed conservative treatment is associated with high pain levels before and remaining after conservative treatment. Abnormally slow motor nerve conduction across the posterior tibial nerve following conservative treatment has also been indicative of higher pain levels and failure of conservative treatment. The best outcomes from surgery were seen with patients who presented with a space occupying lesion. This is due to the fact that the symptoms are a result of a mechanical interface, and when this interface is removed, the symptoms subside accordingly. Even with a space occupying lesion, conservative treatment will likely still be implemented, but surgical intervention is highly likely, and most commonly effective.

An incision is made ten centimeters to the tip of the medial malleolus and two centimeters posterior to the posterior margin of the tibia. During the proximal release, the flexor retinaculum is released from its proximal extent near the medial malleolus to the sustentaculum tali. The tarsal tunnel is followed distally and release of the fascia around the medial and lateral plantar nerve branches should be followed through to the abductor hallucis.

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Tarsal Tunnel release. Image from eorthopod.com

Post-Operative Rehabilitation

From the Kaiser Permanente Orthopaedic Physical Therapy Residency

Phase I: Weeks 1-3

  • Goals: Protect joint/nerve integrity, control inflammation, control pain/edema

Phase II: Weeks 3-6

  • Goals: Prevent contractions and formation of scar tissue adhesions; maintain soft tissue and joint mobility

Phase III: Weeks 6-12 to 24

  • Goals: Normal gait mechanics for walking and running on level surfaces, symmetric ankle mobility and single-leg proprioception, ability to perform repeated single leg heel raises pain free, initiate sport-specific or job specific skill development exercises.

Physical Therapy Management Of Tarsal Tunnel Syndrome

The following is a quick reference of what the PT will find on the Physical Therapy Management of Tarsal Tunnel Syndrome page:

Goals of Conservative/Non-Surgical Treatment for Patients with TTS

  • Optimal Tibial nerve integrity
  • Return to prior level of function in home, work, school, community and leisure activities
Intervention Method
Gait Training Gait analysis on treadmill with mirror for visual feedback to the patient; biofeedback to promote activation of weakened muscles during various phases of gait
Strength, power and endurance training posterior compartment of the lower leg: Posterior Tibialis, & foot musculature: FHL, FDL as tolerated by patient and progressing with improvement of symptoms, i.e. aquatic-to-land-based-to-resisted therapeutic exercise.
Manual Therapy soft tissue mobilization of fascial and myofascial structures potentially causing entrapment; neural mobilization: sciatic nerve glides
Modalities
Electrical Stimulation NMES (reeducation of impaired musculature), TENS (pain relief)
Compression, Bracing taping to maintain ideal foot biomechanics
Orthotics maintain the arch, limit excessive motion that may compress branches of the Tibial nerve

Physical Therapy Implications Post-Surgical Management of Tarsal Tunnel Syndrome (Post Tarsal Tunnel Release)

Phase I for Immobilzation and Rehabilitation: Weeks 1-3

Goals:

  • Protect joint/nerve integrity
  • Control Inflammation
  • Control pain/edema
Intervention Method
Passive Range of Motion (PROM) hallux, phalange, and ankle PROM in order to prevent fibrosis of the Flexor Hallucis Longus, Flexor Digitorum Longus and Posterior Tibialis tendons as they traverse through the tarsal tunnel
Education: Wound Care Instruct in surgical site protection and infection prevention strategies
Edema Management Hands On Treatment for Tarsal Tunnel Syndrome: The following techniques may be helpful in reducing symptoms of tarsal tunnel syndrome. They may be in the order below, or in a different order with different emphasis depending on the clinical situation. Milking fluid from the tarsal tunnel, releasing the flexor retinaculum, milking fluid from the ankle joint, milking fluid from within the tibial nerve, releasing the abductor hallucis muscle, neural sliding and gliding of the tibial nerve relative to the flexor retinaculum, stretching the tibial nerve at the tarsal tunnel to release adhesions within the nerve. SOURCE: http://www.nervemobilization.com/tarsal-tunnel-syndrome

Phase II for Immobilization and Rehabilitation: Weeks 3-6

Goals:

  • Prevent contractions and formations of scar tissue adhesions
  • Maintain soft tissue and joint mobility
Intervention Method
Weight Bearing Progression non-weight bearing to weight bearing as tolerated
PROM, Active Assisted Range of Motion (AAROM), and Active Range of Motion (AROM) Ankle ROM out of splint; passive dorsiflexion with towel or strap progressing to gentle, pain free, weight-bearing dorsiflexion stretching
Fibrosis, Adhesion Prevention Initiate tibial nerve glides: start with anti-tension techniques of the tibial nerve(plantar flexion and inversion) moving from the hip or knee. Progress to mobilization of the foot into dorsiflexion and eversion as irritability decreases

Phase III for Immobilization and Rehabilitation: Weeks 6-12 to 24

Goals:

  • Normal gait mechanics for walking and running on level surfaces
  • Symmetric ankle mobility and single-leg proprioception
  • Ability to perform repeated single leg heel raises pain free
  • Initiate sport-specific or job-specific skill development exercises
Intervention Method
Gait training Progress to walking without splint to pain free tolerance
Strengthening Pain free resistive ankle exercises using theraband progressing to body weight exercises: partial-to-full weight bearing progression; evaluate compensations and muscular weakness
Flexibility Progress to initiate body weight stretching over incline as tolerated

Other Web-Based Resources

Patient resource from the U.S. National Library of Medicine and PubMed Health; Tibial Nerve Dysfunction

Patient's Guide to Foot Anatomy

Patient Education: Tarsal Tunnel Syndrome

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