Tarsal tunnel syndrome is defined as entrapment of the tibial nerve or branches of the nerve within, or distal to, the tarsal tunnel of the medial ankle.1 This is an extremely rare diagnosis and can reasonably be thought of as a pain syndrome.
Tarsal tunnel syndrome is often idiopathic; however, true compression of the tibial nerve can occur. Extrinsic causes include trauma (including ill-fitting footwear or tight plaster casts), post-operative scarring, anatomic abnormalities (tarsal coalition, osteophyte, osteochondroma), biomechanical abnormalities (rearfoot varus or valgus), lower extremity edema (myxedema in hypothyroidism, pitting edema from volume overload), systemic inflammatory arthropathies, or diabetes. Intrinsic causes include tendinopathy (tenosynovitis), perineural scarring or tumor, and space occupying lesions (ganglion cyst, lipoma, or varicose veins).2,3,4 Repetitive eversion and dorsiflexion compresses the tunnel while repeated plantarflexion and inversion can lead to stretch of the tibial nerve.3,5 Compared with carpal tunnel syndrome, chronic repetitive injury is believed to be a rare etiology.6
Epidemiology including risk factors and primary prevention
Tarsal tunnel syndrome is a rare disease defined by the National Organization for Rare Disorders (NORD) with no known prevalence or incidence.7
The tibial nerve branches from the sciatic nerve which is composed of the L4-S3 nerve roots.5 It descends posterior and inferior to the medial malleolus where it enters the tarsal tunnel, a narrow fibro-osseous space bound by the medial malleolus antero-superiorly, posterior talus and calcaneus laterally, and is held to the bone by the flexor retinaculum. The tarsal tunnel encompasses tendons of the posterior tibialis, flexor hallucis longus (FHL), flexor digitorum longus (FDL), posterior tibial artery and vein, and posterior tibial nerve. The medial calcaneal nerve provides sensation to the posteromedial heel. It typically branches off proximal to the tarsal tunnel but in 25% of patients it branches off the lateral plantar nerve.8 The tibial nerve then travels between the FDL and FHL muscles before it divides into the mixed sensory motor medial and lateral plantar nerves in the tarsal tunnel. The medial plantar nerve provides sensation to the medial plantar foot and first 3.5 digits and motor function to the lumbricals, abductor hallucis, flexor hallucis brevis, and flexor digitorum brevis. The lateral plantar nerve provides sensation to the medial calcaneus, lateral heel, and motor function to the flexor digitorum brevis, quadratus plantae, interossei, and abductor digiti minimi. Tarsal tunnel syndrome refers to compression of the posterior tibial nerve or its branches (medial or lateral plantar nerves) as they travel through the tarsal tunnel. A common site of compression is the decussation of the FDL and FHL.9
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
Symptoms are often nonspecific and include numbness, tingling, or burning of the plantar foot and distal toes or perimalleolar area.1,10 As the condition progresses, pain may disrupt sleep and radiate proximally.1 Intrinsic foot muscle atrophy may rarely be seen in severe and/or chronic cases.1,10 Medial and lateral plantar neuropathies present similarly with intermittent foot pain and paresthesias, exacerbated by activity.11 Neuropathy of the deep peroneal, medial, and intermediate dorsal cutaneous nerves presents with symptoms of pain, numbness, and paresthesias over the dorsal foot. Calcaneal neuropathy presents with heel pain and numbness.6,11
Essentials of Assessment
Because symptoms are vague and nonspecific, the differential diagnosis for foot pain and paresthesias is broad. Unilateral symptoms are often due to lumbosacral radiculopathy, musculoskeletal injuries, or peroneal neuropathy at the fibular head. A presenting symptom of “arch pain” commonly is due to plantar fasciitis.8 Other causes include morton neuroma, FHL or FDS tendonitis, and proximal tibial neuropathy.3 The patient should be asked about recent or remote trauma including sprains, strains, and fractures.
Bilateral symptoms may suggest peripheral neuropathy or lumbar stenosis. A history should include exploring large fiber peripheral neuropathy risk factors (alcohol use disorder, thyroid disease, chronic kidney disease, B12 deficiency, diabetes) and a family history of foot deformity or neuropathy. Small fiber neuropathy may be secondary to a rheumatologic disorder (lupus, inflammatory arthropathies). Any neuropathic etiology may be described as worsening nocturnally.8 Vascular pathology, specifically claudication, its associated risk factors, and varicose veins, should also be investigated.
A diagnosis of tarsal tunnel syndrome can be seriously considered once other more common etiologies have been ruled out. Although differentiation may not be possible, symptoms can vary depending on which portion of the posterior tibial nerve or its branches is compressed.8 The prior questioning of FDS or FHL tendonitis, varicose veins, and trauma may support the ultimate diagnosis of tarsal tunnel syndrome as all can cause posterior tibial nerve compression in the tarsal tunnel. In fact, 43% of patients with diagnosis of tarsal tunnel syndrome report antecedent ankle trauma.8
Examination should start with visualization of the lower extremities, evaluation for atrophy, abnormal hair patterns, edema, or skin changes. Varicosities may be more apparent with standing.11 The feet should be evaluated for muscular atrophy, pes planus, talipes equinovarus, and toe contractures. Manual muscle testing of foot intrinsic muscles can be challenging, and weakness is often a late finding. However, an attempt at evaluating strength of toe flexion and abduction testing can be helpful.1,3,8,10 It is essential to examine the lumbar spine and perform a thorough lower extremity neurologic exam including manual muscle testing, reflexes, and dermatomal and peripheral nerve based sensory testing.
Musculoskeletal exam of the ankle and foot is paramount. Passive and active ankle range of motion should be assessed, noting any positions that increase symptoms. Palpation of the deltoid ligament, calcaneus, plantar fascia, tarsals, and metatarsals may localize to bony or soft tissue etiology.
A Tinel test (tapping over the tarsal tunnel repeatedly causing pain or paresthesia in the nerve distribution) may be added but the low sensitivity (25-75%) and specificity (70-90%) should be noted.8 The dorsiflexion-eversion test (passively dorsiflex/evert the ankle to end range of motion and hold for 10 seconds to reproduce symptoms) has improved sensitivity (0.98) and specificity (0.86).3,8 The Trepman test (plantarflexion and inversion resulting in pain and numbness at the ankle or plantar surface of the foot) can also be used with excellent diagnostic value (sensitivity 1.00, specificity 1.00).3 Lastly, the triple compression stress test (TCST) (plantarflexion, inversion, and added compression of the posterior tibial nerve) can provoke entrapment symptoms and has been noted to have high specificity (85.9% and 100% specificity).12
Shoes can be inspected for wear pattern, particularly when considering anterior tarsal tunnel syndrome, an entrapment of the deep peroneal nerve under the extensor retinaculum of the ankle, or medial and intermediate dorsal cutaneous neuropathy. Medial heel wear pattern can indicate excessive pronation.
Gait analysis can help contextualize the functional impact of the condition, but often is non-specific. Gait deviations may include excessive pronation or supination and inversion or eversion and may be generally antalgic.8 The Coleman Block Test can assess hindfoot mobility and pronation.13 Other biomechanical derangements in knee, hip, pelvis, or spine should be assessed because they may contribute to foot pain. Proprioception and balance testing can be considered as well.
Labs should be tailored to suspected diagnoses. To evaluate common causes of peripheral neuropathy, basic metabolic panel, thyroid stimulating hormone, hemoglobin A1C, and B12 levels can be assessed. Complete blood count, erythrocyte sedimentation rate, and C-reactive protein can be ordered if inflammatory arthropathy is suspected.
Standing anterior-posterior and lateral ankle and foot radiographs can evaluate for bony abnormalities including fractures, osteophytes, and abnormal foot alignment. Magnetic resonance imaging (MRI) can help exclude other soft tissue causes (cyst, mass) but is not sensitive for tarsal tunnel syndrome. Ultrasound uniquely can evaluate the posterior tibial nerve for localized compression by measuring within tunnel-to-proximal tunnel cross sectional area (CSA) ratio and within tunnel CSA.14 Additionally, ultrasound can dynamically assess the medial ankle, looking for mechanical compression.
Supplemental assessment tools
Electrodiagnostic testing can be useful for ruling out mimicking conditions such as L4-S1 radiculopathy or more proximal tibial neuropathy. However, for specific evaluation of tarsal tunnel syndrome, it can be inaccurate. A normal study does not exclude the diagnosis.4 False positives have been recorded in up to 43% of normal patients.15 Neurodiagnostic studies typically include medial and lateral plantar sensory nerve conduction studies (NCS) and tibial motor NCS to the abductor hallucis and abductor digiti minimi with optional mixed medial and lateral plantar NCS. Sensory changes (slowed conduction velocity across the tarsal tunnel and/or small amplitude) are more sensitive than motor (prolonged distal onset latency) or mixed NCS (prolonged peak latency or slowed conduction velocity across the tarsal tunnel). Needle electromyography is not necessary for diagnosis but can be performed to rule out radiculopathy or other peripheral mononeuropathies.16
Early predictions of outcomes
Shorter duration of symptoms (<12 months), younger age, lack of motor deficits, and focal compression have all been associated with better outcomes.17-30 Improvement in cases of intermittent compression due to vascular dilation or iatrogenic etiology is less reliable.19 While sensorimotor deficits may not improve after 10 months of symptoms, surgical decompression can hasten further strength loss.20 Posterior tibial nerve compression caused by ganglion cyst may improve with resection but can recur.19,21 Unfortunately, neuropathy diagnosed with ultrasound or electromyography has not been found to correlate with surgical results.19
In general, healthy eating habits, weight loss, and activity modifications may be beneficial. In patients with anterior tarsal tunnel syndrome, tight fitting shoes should be avoided. For those with lateral or medial plantar neuropathy, or ankle instability due to ligamentous laxity, a decrease in activity may be necessary. Focus should also be placed on avoidance or control of peripheral neuropathy risk factors.
Social role and social support system
Social support systems should be discussed with the patient. Social support groups are available for obesity, alcoholism, and chronic conditions, such as inflammatory arthritis.
Vocational training or professional modifications may need to be considered. Manual laborers are thought to have worse outcomes with tarsal tunnel syndrome for unclear reasons.23 Consideration of work environment (heights or extreme hot/cold temperatures) should be considered when neuropathy is suspected.
Rehabilitation Management and Treatments
At different disease stages
Treatment of tarsal tunnel syndrome or any intrinsic foot neuropathy should begin with noninvasive strategies, especially in the absence of motor weakness or atrophy. Because obesity may predispose patients to tarsal tunnel syndrome, weight loss should be emphasized.23 Anti-inflammatory medications may provide relief.11,15 Physical therapy may help correct muscle imbalances and include modalities such as taping, stretching, icing, bracing, massage, and ultrasound.14 Orthotics can improve foot alignment thereby preventing contractures and potentially improving gait.10,11,15 A medial heel wedge may reduce traction on the nerve by inverting the heel.8 Immobilization with a night splint or removable boot walker may also help biomechanical induced symptoms.15 Specific etiologies for tarsal tunnel syndrome or any intrinsic foot neuropathy should be treated, such as varicose vein management, ganglion cyst aspiration, or tumor resection.15
When conservative measures fail or significant strength deficits are present, surgical release of the tarsal tunnel may be indicated, but results are mixed with success rates ranging 44% to 96%.11,15 Results are more consistent when the etiology is constant compression rather than iatrogenic or intermittent compressive vascular dilation.19 Surgical failures have been identified for incomplete releases, especially at the level of the distal tarsal tunnel, and cases in which compression is caused by ganglion cysts which can recur.19,21
Coordination of care
Team members may include a physiatrist, physical therapist, orthotist, interventionalist for injections, podiatrist, and a foot and ankle surgeon.
Patient & family education
Patient education on their disease and contributing factors can empower them to avoid exacerbating symptoms. Use of proper fitting shoes and orthotics should be discussed. Patients should be encouraged to manage contributing conditions, such as diabetes. In general, weight loss is encouraged, and significant alcohol intake is discouraged.
There is interest in making intervention as minimally invasive as possible for cases of tarsal tunnel syndrome when conservative management fails. Peripheral nerve stimulation, nerve hydrodissection, and ultrasound guided tarsal tunnel release have all been reported. 25-30
Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
- Tarsal tunnel syndrome is rare, and the diagnosis should be viewed as one of exclusion unlike other entrapment neuropathies such as carpal tunnel syndrome. Rule out more common conditions, such as systemic distal polyneuropathy or common musculoskeletal complaints, such as a sprain or strain.
- If electrodiagnostic testing reveals abnormalities in the distribution of the tibial nerves bilaterally, polyneuropathy is a more likely explanation than bilateral tarsal tunnel syndrome.
- When diagnosing tarsal tunnel syndrome, consider underlying causes, such as mass lesions, inflammatory arthritis, or diabetes.
- Treatment of tarsal tunnel syndrome is guided by etiology. In general, management of comorbid conditions such as diabetes or obesity, as well as conservative management is most effective. Invasive procedures have inconsistent results in treating symptoms.
Cutting Edge/ Emerging and Unique Concepts and Practice
Patients with idiopathic tarsal tunnel syndrome have demonstrated good results with ultrasound-guided decompression of the proximal and distal tarsal tunnel syndrome with 76.5% excellent and 13.6% good results.25 Decompression with ultra-minimally invasive surgery dropped measured intra-compartmental pressures on the tarsal tunnel, medial and lateral plantar tunnels.26 Ultrasound guided injection (hydrodissection) with either local anesthetic and/or steroid has shown to be a helpful option with similar pain reduction compared to surgical treatment and fewer additional foot and ankle post-procedure pathologies.27,28 Successful ultrasound guided hydrodissection of the medial and lateral plantar nerves has also been reported.29 Additionally, percutaneous peripheral nerve stimulation of the tibial nerve proximal the tarsal tunnel is being investigated to improve cases of foot and medial ankle neuropathic pain.30
Gaps in the Evidence-Based Knowledge
- Epidemiology of tarsal tunnel syndrome has not been defined.
- There are no recommended treatment guidelines for tarsal tunnel syndrome.
- Electrodiagnostic studies are level C recommendations for confirming the diagnosis of tarsal tunnel syndrome.16
- Larger studies evaluating minimally invasive versus open surgical procedures are needed to help guide interventional choice when conservative management fails.
- Lisa JA, Saeed, MA. The tarsal tunnel syndrome. Muscle Nerve. 1983;6:664-670.
- Scura D, García-López B. Electrodiagnostic Evaluation Of Tarsal Tunnel Neuropathy. In: StatPearls. Treasure Island (FL): StatPearls Publishing; November 3, 2021.
- Bowley MP, Doughty CT. Entrapment Neuropathies of the Lower Extremity. Med Clin North Am. 2019;103(2):371-382. doi:10.1016/j.mcna.2018.10.013
- Nelson SC. Tarsal Tunnel Syndrome. Clin Podiatr Med Surg. 2021;38(2):131-141. doi:10.1016/j.cpm.2020.12.001
- Banik S Sr, Guria LR. Variable Branching Pattern of Tibial Nerve in the Tarsal Tunnel: A Gross Anatomical Study With Clinical Implications. Cureus. 2021;13(3):e13729. Published 2021 Mar 6. doi:10.7759/cureus.13729
- Preston DC, Shapiro BE. Tarsal tunnel syndrome. In: Preston DC, Shapiro BE, eds. Electromyography and Neuormuscular Disorders. 2nd ed. Elsevier; 2005:365-372.
- Kennedy, J, Shimozono, Y, Smyth, N. Tarsal Tunnel Syndrome. National Organization of Rare Disorders. 2018. https://rarediseases.org/rare-diseases/tarsal-tunnel-syndrome/
- Kiel J, Kaiser K. Tarsal Tunnel Syndrome. In: StatPearls. Treasure Island (FL): StatPearls Publishing; August 12, 2021.
- Oh SJ, Lee KW. Medial plantar neuropathy. Neurology. 1987;37:1408-1410.
- Oh SJ, Meyer RD. Entrapment neuropathies of the tibial (posterior tibial) nerve. Neurol Clin. 1999;17:593-615.
- Williams TH, Robinson AH. Entrapment neuropathies of the foot and ankle. Orthop Trauma. 2009;23:404-411.
- Abouelela AA, Zohiery AK. The triple compression stress test for diagnosis of tarsal tunnel syndrome. Foot (Edinb). 2012;22(3):146-149. doi:10.1016/j.foot.2012.02.002.
- Wheeless, C. Coleman Block Test. Wheeless’ Textbook of Orthopaedics. 2022. Duke University Medical Center. oot/coleman-block-test/
- Tawfik EA, El Zohiery AK, Abouelela AA. Proposed Sonographic Criteria for the Diagnosis of Idiopathic Tarsal Tunnel Syndrome. Arch Phys Med Rehabil. 2016;97(7):1093-1099. doi:10.1016/j.apmr.2015.11.012
- Ahmad M, Tsang K, Mackenney PJ, Adedapo AO. Tarsal tunnel syndrome: A literature review. Foot Ankle Surg. 2012;18(3):149-152. doi:10.1016/j.fas.2011.10.007
- Patel AT, Gaines K, Malamut R, et al. Usefulness of electrodiagnostic techniques in the evaluation of suspected tarsal tunnel syndrome: an evidence-based review. Muscle Nerve. 2005;32:236-240.
- Antoniadis G, Scheglmann K. Posterior tarsal tunnel syndrome: diagnosis and treatment. Dtsch Arztebl Int. 2008;105:776-781.
- Sammarco GJ, Chang LJ. Outcome of surgical treatment of tarsal tunnel syndrome. Foot Ankle Int. 2003;24:125-131.
- Lalevée M, Coillard JY, Gauthé R, et al. Tarsal Tunnel Syndrome: Outcome According to Etiology [published online ahead of print, 2021 Oct 23]. J Foot Ankle Surg. 2021;S1067-2516(21)00396-3. doi:10.1053/j.jfas.2021.10.014
- Takakura Y, Kitada C, Sugimoto K, Tanaka Y, Tamai S. Tarsal tunnel syndrome. Causes and results of operative treatment. J Bone Joint Surg Br. 1991;73(1):125-128. doi:10.1302/0301-620X.73B1.1991745
- Yalcinkaya M, Ozer UE, Yalcin MB, Bagatur AE. Neurolysis for failed tarsal tunnel surgery. J Foot Ankle Surg. 2014;53(6):794-798. doi:10.1053/j.jfas.2014.05.012
- Gondring WH, Trepman E, Shields B. Tarsal tunnel syndrome: assessment of treatment outcomes with an anatomic pain intensity scale. Foot Ankle Surge. 2009;15:133-138.
- Antoniadis G, Scheglmann K. Posterior tarsal tunnel syndrome: diagnosis and treatment. Dtsch Arztebl Int. 2008;105:776-781.
- Cimino WR. Tarsal tunnel syndrome: review of the literature. Foot Ankle. 1990;11:47-52.
- Iborra A, Villanueva M, Sanz-Ruiz P. Results of ultrasound-guided release of tarsal tunnel syndrome: a review of 81 cases with a minimum follow-up of 18 months. J Orthop Surg Res. 2020;15(1):30. Published 2020 Jan 28. doi:10.1186/s13018-020-1559-1
- Iborra Marcos A, Villanueva Martinez M, Sanz-Ruiz P, Barrett SL, Zislis G. Ultrasound-Guided Proximal and Distal Tarsal Decompression: An Analysis of Pressures in the Tarsal, Medial Plantar, and Lateral Plantar Tunnels. Foot Ankle Spec. 2021;14(2):133-139. doi:10.1177/1938640020905423
- Park JS, Atesok K, Pierce J, Small B, Perumal V, Cooper MT. The Course of Tarsal Tunnel Syndrome after Ultrasound-Guided Injections. Foot Ankle Orthop. 2022;7(1):2473011421S00389. Published 2022 Jan 21. doi:10.1177/2473011421S00389
- Reilly, I.; Uddin, A. High Volume Injection (Hydrodissection) for Tarsal Tunnel Syndrome Using Peripheral Nerve Stimulation: Treatment Protocol. Preprints 2021, 2021010366 (doi: 10.20944/preprints202101.0366.v1).
- Buchanan P, Kumar S, Stitik TP. Poster 219. Medial and lateral plantar nerve hydrodissection in tarsal tunnel syndrome: a case report. PM&R. 2014 6(9):S261.
- Hanyu-Deutmeyer A, Pritzlaff SG. Peripheral Nerve Stimulation for the 21st Century: Sural, Superficial Peroneal, and Tibial Nerves. Pain Med. 2020;21(Suppl 1):S64-S67. doi:10.1093/pm/pnaa202
Original Version of the Topic:
Michael K. Mallow, MD. Tarsal tunnel syndrome and intrinsic neurologic foot disorders. 10/30/2013
Previous Revision(s) of the Topic:
Michael K. Mallow, MD. Tarsal tunnel syndrome and intrinsic neurologic foot disorders. 4/9/2018
Kristina Barber, MD
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Lindsay Burke, MD
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Malia Cali, MD
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Adele Meron, MD
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