Review Article Entrapment Neuropathy About the and : An Update

Abstract Gregory Pomeroy, MD Occurrences of entrapment neuropathies of the lower extremity are James Wilton, DPM relatively infrequent; therefore, these conditions may be underappreciated and difficult to diagnose. Understanding the anatomy Steven Anthony, DO of the peripheral and their potential entrapment sitesis essential. A detailed physical examination and judicious use of imaging modalities are also vital when establishing a diagnosis. Once an accurate diagnosis is obtained, treatment is aimed at reducing external pressure, minimizing , correcting any causative foot and ankle deformities, and ultimately releasing any constrictive tissues.

erve entrapment of the lower leg, as the nerve passes posterior to Nankle, and foot is relatively the medial and medial to uncommon. Variable anatomy pro- the talus and . The term is duces a spectrum of symptoms and also sometimes used to describe diagnostic findings. Any of the five entrapment of any of the major ter- From the New England Foot and Ankle Specialists, Mercy Hospital, major nerves (tibial, deep peroneal, minal branches after they leave the Portland, ME (Dr. Pomeroy), Valley superficial peroneal, sural, saphenous) proper. The forms Regional Hospital, Claremont, NH and their branches may become en- the anterior wall of the tunnel, the (Dr. Wilton), and Advanced trapped at various locations. To estab- talus and the calcaneus form the lat- Orthopedic Center, Port Charlotte, FL (Dr. Anthony). lish an accurate diagnosis, physicians eral wall, and the flexor retinaculum must rely on a comprehensive physical forms the roof. In most patients, the Dr. Pomeroy or an immediate family examination and a thorough under- divides into three terminal member is a member of a speakers’ bureau or has made paid standing of the relevant anatomy. branches (ie, medial , presentations on behalf of Stryker, is Anatomic studies have helped identify , medial calcaneal an employee of Stryker and specific areas in which nerves are com- nerve) within the tarsal tunnel.1 Osteomed, and serves as a board monly compressed. Advanced imaging, Tarsal tunnel entrapment may be member, owner, officer, or committee member of the New England including MRI and ultrasonography, divided into proximal and distal Orthopaedic Society. Dr. Wilton or an and nerve conduction velocity (NCV) syndromes; a proximal syndrome is immediate family member serves as studies have improved the ability to compression of the tibial nerve, and a board member, owner, officer, or localize the area of entrapment. When a distal syndrome implies compres- committee member of the Association of Extremity Nerve Surgeons. Neither an entrapment is diagnosed and local- sion of one or more of the terminal Dr. Anthony nor any immediate family ized, effective treatment is aimed at branches.2 In most persons, the member has received anything of removing any external compressive nerve branches within the tunnel; value from or has stock or stock factors, decreasing inflammation and therefore, distal compressions may options held in a commercial company or institution related directly or edema, correcting any deformities or be the result of compression within indirectly to the subject of this article. osseous abnormalities, and ultimately the tarsal tunnel proper or com- J Am Acad Orthop Surg 2015;23: releasing any tissues compressing the pression distal to the tunnel as the 58-66 affected nerve. terminal branches traverse the fas- http://dx.doi.org/10.5435/ cial planes of the foot. Distal en- JAAOS-23-01-58 trapments outside the tarsal tunnel include compression of the medial Copyright 2014 by the American ’ Academy of Orthopaedic Surgeons. Tarsal tunnel syndrome is an plantar nerve (ie, jogger s foot) and entrapment neuropathy of the tibial compression of the first branch of

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the lateral plantar nerve (ie, Baxter used to confirm entrapment and may had had symptoms for ,1year. nerve). be considered as a supplement to Takakura et al16 suggested that a careful and precise history and recovery of the nerve was poor when physical examination; however, they decompression was delayed, whereas Proximal Tarsal Tunnel cannot be used exclusively to rule in or early diagnosis and intervention re- rule out tarsal tunnel syndrome. sulted in an excellent prognosis. The tibial nerve is most commonly (EMG) studies Potential complications with release of compressed in the tarsal tunnel proper. have been shown to have a high false- the tarsal tunnel may include contin- Space-occupying lesions have been positive rate when used for testing the ued symptoms secondary to an identified with tarsal tunnel syn- intrinsic muscles of the foot, and NCV incomplete release, or abundant scar drome, including tenosynovitis, gan- studieshavebeenshowntohave formation, wound complications, and glion, lipoma, venous engorgement, a high false-negative rate.10,11 Patel iatrogenic neurovascular injury.13,14 neurilemmoma, exostosis, and acces- et al12 conducted an evidence-based sory musculature within the canal.3 review of electrodiagnostics in tarsal Other etiologies include bony or car- tunnel syndrome and concluded that Jogger’s Foot tilaginous prominences, trauma, and sensory NCV may be more likely to be fibrosis or thickening of the flexor abnormal than motor NCV, but the The may be retinaculum.4 It also is the senior true sensitivities and specificities of compressed between the abductor author’s experience that significant these tests are unknown.12 hallucis and its origin at the hindfoot pronation may place exces- Nonsurgical management is typically navicular and calcaneus, between the sive tension on the nerve. attempted before surgical intervention. belly and Patients typically report diffuse The mainstays of nonsurgical care are the knot of Henry, or as it passes along the medial ankle and plantar anti-inflammatory medication, activity through the medial intermuscular sep- foot. The pain may be exacerbated by modifications, night splinting, physical tum.17,18 Patients report exercise- activity and alleviated by rest. Symp- therapy, and discontinuation of the use induced pain on the medial plantar toms are often present at night. Patients of any compressive clothing or foot- surface of the foot. The pain often may have difficulty describing the wear. Corticosteroid injections may radiates distally to the plantar surface nature of the pain, but they typically provide short-term relief, but support- of the first, second, and third and characterize it as burning, shooting, ive evidence is lacking to recommend may radiate proximally into the tingling, numbing, or electric. These these treatments. medial heel and ankle. Long-distance same symptoms may radiate proxi- Surgical release of the tibial nerve runners with valgus hindfeet may be mally into the calf (ie, Valleix phe- and its terminal branches is recom- more susceptible to jogger’s foot.17 nomenon) or radiate distally in the mended when nonsurgical measures Physical examination findings distribution of any and all terminal fail. The entire flexor retinaculum include a positive Tinel sign at the branches of the tibial nerve.5,6 Inter- should be released. An incomplete plantar border of the navicular tuber- mittent numbness in the plantar foot release has been shown to be a cause osity and dysesthesias along the heel, also may be present. A positive Tinel for continued pain after surgery.13 medial arch, and first through third sign may often be elicited, and patients Distal release of the tunnels of the toes. Patients may have hindfoot val- may report pain with deep palpation medial plantar, lateral plantar, and gus and pes planus. Their shoe wear in the area of the tarsal canal. The calcaneal nerves is also advocated should be examined for any sources of dorsiflexion-eversion test may also and should be considered.9 external compression (eg, excessive or reproduce symptoms.7 Other independent factors that may rigid arch support).17 Radiographs Radiographs and MRI or ultraso- affect outcomes are the cause of the may be used to rule out bony abnor- nography should be used to identify compression and the timing of sur- malities and to assist in diagnosing any bony or soft-tissue etiologies. gery.4,6,14-16 If the symptoms are sec- causative deformities of the foot. MRI Ultrasonography is reliable and cost ondary to a space-occupying lesion, findings may include space-occupying effective in some studies, but the results resection may lead to improved out- lesions and denervation edema of the are operator dependent.2,8 Electro- comes compared with those of pa- affected muscles.18 diagnostic studies are recommended tients who have no identifiable Initial nonsurgical management is to rule out more proximal nerve lesion.14,15 Sammarco and Chang6 similar to the care provided for pathology (ie, double crush syndrome) reported on 75 patients; these authors proximal tarsal tunnel syndrome. If or underlying neuropathy or myopa- noted improvements in foot scores these modalities fail to provide relief, thy.9 Electrodiagnostic studies are also and better outcomes in patients who surgical release should be considered.

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Figure 1 Further diagnostic studies may be beneficial if the diagnosis is unclear. Plain radiographs may reveal underlying bony and structural abnormalities, and electrodiagnostic studies may assist with confirming the diagnosis and determining the exact location of the compression.12 These modalities, used in conjunction with a careful history and physical exami- nation, may reveal a more proximal nerve injury or may help rule out an underlying neuropathy or myopathy. Atrophy of the abductor digiti minimi on MRI has been suggested as a pos- sible sign of entrapment.18,21,22 How- ever, fatty atrophy of the abductor digiti minimi on MRI is also prevalent in patients with no entrapment.21,22 Surgical intervention is often required. The recommended treat- ment is complete neurolysis by first releasing the proximal deep fascia of the abductor hallucis muscle. The Illustration showing a coronal view of the hindfoot and demonstrating two areas nerve is then followed distally and (1, 2) of possible impingement of the first branch of the lateral plantar nerve (ie, Baxter nerve). (Reproduced from Lareau CR, Sawyer GA, Wang JH, DiGiovanni released from any entrapment CW: Plantar and medial heel pain: Diagnosis and management. J Am Acad caused by the medial Orthop Surg 2014;22[6]:372–380.) or the flexor digitorum brevis at their insertion to the calcaneus. If there is The deep fascia of the abductor and inflammation about the plantar an impinging bone spur in this area, hallucis should be released from its fascia origin19,20 (Figure 1). a small portion may be removed if origin on the calcaneus to the knot Compression of the first branch of necessary, but removing the entire spur of Henry. Consideration should be the lateral plantar nerve presents as is not recommended because this action given to extending the release proxi- chronic medial plantar heel pain, fre- may lead to adverse outcomes.19 Sin- mally to include the flexor retinacu- quently similar in location to that of naeve and Vandeputte23 reported lum and the tibial nerve because this . However, in contrast excellent outcomes using this technique branch may be compressed distally or to plantar fasciitis, symptoms are more for recalcitrant inferomedial heel pain. within the tarsal tunnel proper.1,2 proximal and medial, tend to worsen They performed a partial release of with activity, and may be exacerbated the medial plantar fascia in all patients Baxter Neuropathy with eversion and abduction of the and performed a partial resection of foot.20 The pain may also radiate an impinging bone spur in 61% of Entrapment of the first branch of the proximally into the medial ankle or patients.23 lateral plantar nerve was initially distally and laterally across the plantar described by Baxter and Thigpen.19 It foot. Paresthesias and weakness are typically occurs between the fascia of not typically reported. On physical Soleal Sling Syndrome the abductor hallucis and the quad- examination, the most common find- ratus plantae muscles, but it may also ing is tenderness over the nerve deep Soleal sling syndrome refers to occur between the flexor digitorum to the abductor hallucis. Palpation of the entrapment of the tibial nerve in the brevis muscle and the calcaneus.19,20 this area should reproduce symptoms proximal leg by a fibrous sling at the Multiple etiologic factors have been and may cause radiation of the pain origin of the soleus muscle24 (Figure 2). proposed, including stretching of the proximally or distally.19 More proxi- Patients may report calf pain and have nerve in running athletes, muscle mal or distal sites of entrapment symptoms similar to those of tarsal hypertrophy, bone spurs, and bursitis should be ruled out with palpation. tunnel syndrome; it is not uncommon

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Figure 2

Illustration showing a coronal view of the proximal leg and demonstrating the tibial nerve passing deep to the fibrous soleal sling, connecting the proximal fibular and tibial origins of the soleus. FDL = flexor digitorum longus, FHL = flexor hallucis longus, PT = posterior tibialis

forpatientstohaveahistoryof symptom is critical for making this proximal or distal nerve compres- a failed tarsal tunnel release.25 As diagnosis. Patients may have sensory sion.25,26 Newer high resolution such, the differential diagnosis of changes anywhere along the distribu- (ie, 3 T) MRI and magnetic resonance patients with a failed tarsal tunnel tion of the tibial nerve. Weakness also neurography protocols may be bene- syndrome must include the soleal sling may be present, especially in the flexor ficial in confirming the diagnosis.25-27 syndrome.25,26 hallucis longus. NCV studies and Nonsurgical management should Physical examination typically gen- EMG are difficult to perform because consist of modification of pain- erates pain with gentle palpation of of the depth of the nerve at this level inducing activities and discontinued the posterior calf at the level of the and have shown little benefit, use of restrictive clothing or boots. soleal sling, approximately 9 cm below except when they are used to rule Anti-inflammatory medications and the popliteal flexion crease.24 This out and more nerve-modulating medications may

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also be of some benefit. When non- Most patients can be diagnosed clin- the need for accommodative foot- surgical management fails to provide ically, but in abnormal presentations wear. Using this scale, they reported relief, surgical decompression is rec- the clinician may use radiographs, that 78% of patients had good or ommended. An open release of the ultrasonography, and MRI to help excellent results, with only 3% having tibial nerve at the soleal sling and the confirm the diagnosis. Radiographs are a poor outcome. However, Womack freeing of any other constrictive tis- used to rule out differential diagnoses, et al42 used the same scale and re- sues from the nerve have shown such as osteonecrosis, stress fracture, or ported that only 51% of patients had promising outcomes with no major arthritis at the MTP . Ultrasonog- good or excellent results in their series, complications.25,26 raphy and MRI can both reliably with 40% having a poor outcome. identify the neuroma.2,18,32 However, The most common complication is identification of a neuroma with these recurrence of pain as a result of Morton Neuroma modalities does not correlate with inadequate nerve resection or symptomatology; many asymptomatic removal of the incorrect tissue (ie, Morton neuroma is an entrapment patients may also have positive MRI commonly the lumbrical tendon or neuropathy of the interdigital nerve or ultrasonography results.33-35 These digital artery).43 To avoid these near the distal edge of the inter- tests should be used only to confirm complications, some authors rec- metatarsal ligament, most commonly the diagnosis after clinical suspicion, to ommend decompression of the neu- in the third web space and only rule out other soft-tissues masses, or to roma through an open or endoscopic occasionally in the second web space. assist with injections or surgical plan- approach. The outcomes of these Thus, the diagnosis of second meta- ning; no role exists for electro- procedures are reported to be tarsophalangeal (MTP) instability diagnostic studies.31 excellent in 78% to 96% of pa- must be carefully considered in the Nonsurgical management options tients.44-48 Villas et al45 recently setting of a second web space neu- include custom orthoses, metatarsal advocated a hybrid approach. In- roma. The neuroma itself is a non- pads, accommodative footwear, traoperatively, the nerve is resected if neoplastic lesion consisting primarily NSAIDs, and injections. Corticoste- it is found to be thickened; otherwise, of degenerative changes and peri- roid injections have demonstrated the authors released only the trans- neural fibrosis.28,29 It is unclear unreliable results; the injections pro- verse metatarsal ligament. Total relief where the impingement occurs; some vide good short-term pain relief but of symptoms was achieved in 96% of clinicians believe the primary source little long-term improvement.29,36,37 patients after release and 98% after of entrapment is the intermetatarsal Also, repeated injections of cortico- neurectomy. ligament, whereas other clinicians steroids may result in damage to the believe the primary source is the MTP joint capsule and the plantar metatarsal heads and/or the tissues plate. Serial injections with an alcohol Superficial Peroneal Nerve surrounding the MTP that sclerosing agent are another form of Entrapment compress the nerve.28-31 management; however, the reported Women are affected more than men, clinical results of this therapy have Entrapment of the superficial pero- most likely as the result of wearing been disappointing, and there is neal nerve (SPN) is a relatively rare narrow- box shoes that compress concern for damage the injections cause of chronic leg pain.49-51 The the forefoot. Patients typically report may cause to the surrounding SPN branches from the common burning or electric pain and par- tissues.38,39 peroneal nerve and courses through esthesias in the affected web space and Surgical treatment is indicated when the lateral compartment of the leg, may report the sensation of walking nonsurgical management fails to pro- innervating the and on a lump. On physical examination, vide relief. Historically, the most brevis muscles. However, anatomic symptoms are reproduced with direct common surgical intervention is exci- studies have shown that the nerve pressure placed plantarly between the sion of the neuroma, typically through may travel in the anterior compart- metatarsal heads, or findings indicate a dorsal approach for primary ment in 14% to 17% of patients.50 a positive Mulder sign. Another lesions.29,40,41 Excellent results may The nerve pierces the deep fascia of method of confirming the diagnosis is be achieved but are not guaranteed; the leg and becomes subcutaneous to verify whether the patient reports studies demonstrate good outcomes in approximately 12.5 cm proximal to pain relief following an isolated lido- 51% to 93% of patients.28,29,31,41,42 the tip of the lateral malleolus.49-51 caine injection 2 cm proximal to the Giannini et al28 developed a clinical As the SPN pierces the deep fascia, metatarsal head and plantar to the grading scale based on pain, maxi- it may become entrapped because of intermetatarsal ligament.31 mum walking distance, sensation, and a thickened fascial tunnel, a fascial

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defect and muscle herniation, or the lateral compartment, and the evaluation of the entire DPN from a soft-tissue mass, such as a lipoma.49-51 septum between the two compart- behind the neck of the fibula to the first This condition may also be seen in ments. Results of surgical treatment web space. The precise site of the athletes who have lateral ligament are variable and based on small ret- compression may often be confirmed deficiency or functional ankle insta- rospective studies and case reports. with a local nerve block. bility, thus causing a traction injury to Better evidence is required to make Radiographic evaluation is critical in the SPN. Most patients report activity- specific recommendations, but the the workup because the most common relatedpaintothelowerlaterallegand available research supports surgical causes of anterior tarsal tunnel syn- dysesthesias in the dorsum and lateral decompression after failure of non- drome are trauma and impingement of aspect of the foot. The symptoms may surgical management.49-51 the nerve by osteophytes around the be elicited by inverting and plantar- talonavicular joint.54 MRI may be flexing the ankle and by percussing the used if a space-occupying lesion is nerve as it emerges from the deep Anterior Tarsal Tunnel suspected.18 EMG may be valuable if fascia.49-51 Syndrome latencies are seen in the nerve to the The diagnosis may be made using extensor digitorum brevis, indicating the results of the history and the The deep peroneal nerve (DPN) runs entrapment proximal to the inferior physical examination. NCV studies between the tibialis anterior and the extensor retinaculum.52,55 and EMG are unreliable and do not extensor hallucis longus (EHL) 5 cm Nonsurgical management should alter the course of treatment.49-51 above the ankle mortise. Under focus on reducing any external com- Radiographs may assist in diagnos- the superior extensor retinaculum, pression, stabilizing any ankle laxity, ing any malalignment or instability approximately 1 cm proximal to the and reducing inflammation through that may be generating the pain. ankle joint, the nerve divides into the use of , bracing, Chronic exertional compartment a medial branch and a lateral shoe wear modifications, and anti- syndrome should be considered on branch.18,52-54 The lateral branch inflammatory medications. Surgical the differential diagnosis, and com- courses deep to the inferior extensor release is reserved for recalcitrant partment pressure measurements retinaculum to provide motor inner- cases and should be very site specific may be performed as necessary. A vation to the extensor digitorum bre- to reduce scarring from extensive localized injection of anesthetic at vis and sensation to the ankle joint nerve dissection. The extensor reti- the site of maximal tenderness that andthelateraltarsaljoints.The naculum is released just enough to results in the relief of symptoms can medial branch courses with the dor- decompress the nerve. Complete confirm the suspected diagnosis.52 salis pedis artery under the inferior release may lead to bowstringing of Initial management is directed at extensor retinaculum and provides the tendons. Any osteophytes found removing any external factors that sensation to the first web space.18,52,53 over the ankle joint or over the dorsal may be causing compression and Compression of the DPN and either of edge of the talonavicular joint should stabilizing any instability that may be itsbranchesmayoccurasitpasses be removed. If the extensor hallucis tensioning the nerve. Surgery is rarely through the anterior tarsal tunnel, brevis tendon is compressing the required; however, if required, it which is defined by the inferior nerve, it may be partially resected and often involves a simple decompres- extensor retinaculum superficially and transferred to the EHL.52,54 Dellon54 sion of the fascia around the nerve the talonavicular joint capsule followed 18 patients after surgical exit point, although a complete fas- deeply.53 Other structures passing release of the deep peroneal nerve at ciotomy of the lateral compartment through this tunnel include the dor- the anterior tarsal tunnel and found may be required, especially in pa- salis pedis artery and vein and the that 80% of patients achieved good tients with exertional compartment tendons of the EHL, the tibialis ante- or excellent results at 2-year follow- syndrome.51 Rosson and Dellon50 rior, the extensor digitorum longus, up; no complications were reported. retrospectively reviewed 31 patients and the (Figure 3). and found that 17% of the nerves Patients with compression of the werelocatedintheanteriorcom- lateral branch of the DPN typically partment, 26% traveled through both report dorsal foot pain radiating the anterior and lateral compartments, to the region of the lateral tarsometa- Although rare, entrapment of the and only 57% were located exclu- tarsal joints. Patients with medial nerve sural nerve can occur anywhere in the sively in the lateral compartment. The entrapment report pain and/or numb- leg, ankle, or foot. The most common authors recommended distal fascial ness to the first web space. Exam- sites of compression are along the release of the anterior compartment, ination should include a thorough lateral border of the ankle, the

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Figure 3 impingement or structural abnormali- ties that may be tensioning the nerve. MRI should be considered to rule out soft-tissue masses or other space- occupying lesions that may be com- pressing the nerve.18 Modern NCV study protocols are reliable in con- firming the diagnosis and identifying lumbosacral nerve root pathology.56-58 Treatment of sural nerve entrapment is dependent on accurately identifying the causative factors and the location of the entrapment.58 Any underlying instability or peripheral edema should be addressed first, as should any external factors, such as constrictive shoe wear or symptom- inducing activities. Additionally, if the etiology is posttraumatic or post- operative, the authors recommend a3-to6-monthperiodofobserva- tion, desensitization, and use of neural gliding techniques before pro- ceeding to surgery. Other nonsurgical management options include anti- inflammatory medications, nerve- modulating medications, and steroid injections. Surgical intervention should address any bony abnormalities, de- formities, or joint instability. If no causative factor is identified, efforts should be directed at establishing the exact location of the entrapment. The nerve may then be released from the constrictive tissue, or a nerve resection may be performed. Fabre et al58 re- Illustration showing an anterior view of the foot and ankle and identifying the ported their outcomes after surgical superior and inferior extensor retinacula and their relationships to the deep release of the sural nerve on 18 limbs in peroneal nerve and its medial and lateral branches. 13 athletes. Twelve of the 13 patients were satisfied with the results and were calcaneus, and the fifth metatarsal. lateral leg, lateral ankle, or lateral able to return to sport at the same level. Entrapment is often secondary to foot. Physical examination findings The only complications reported were trauma and/or surgery and the sub- may include a positive Tinel sign along a superficial hematoma in one patient sequent bony overgrowth, soft-tissue the course of the nerve and exacerba- and continued pain in another.58 scarring, or instability.56,57 How- tion of symptoms with plantar flexion ever, atraumatic entrapment of the and inversion of the foot.56,57 How- nerve has occurred where the nerve ever, in the young athlete, the Tinel passes through a fibrous arcade as it sign may be negative, and pain is moves from a deep to superficial often exclusive to the posterolateral Entrapment of the saphenous nerve position along the lateral border of leg adjacent to the musculotendinous about the foot and ankle is also rare. the proximal .58 junction of the Achilles tendon.58 Typically, entrapment occurs more Patients may report pain, burning, Radiographs may be used to identify proximally, but patients often present numbness, or aching in the postero- bony abnormalities that are causing with pain and paresthesias to the foot

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and ankle.52 In the authors’ experi- contents. In this article, references 6, 13. Skalley TC, Schon LC, Hinton RY, Myerson MS: Clinical results following ence, distal entrapment is frequently 7, and 39 are level II studies. Refer- revision tibial nerve release. Foot Ankle Int secondary to trauma and/or surgery. ences 1, 4, 8-10, 13-17, 19, 20, 23, 1994;15(7):360-367.

The diagnosis may be made clinically; 25, 27-29, 32, 33, 36-38, 42-51, 54, 14. Pfeiffer WH, Cracchiolo A III: Clinical however, radiographs, CT, and/or and 56-58 are level IV studies. Ref- results after tarsal tunnel decompression. MRI should be considered to rule out erences 2, 5, 12, 18, 31, 40, 41, 52, J Bone Joint Surg Am 1994;76(8): 1222-1230. bony or soft-tissue obstructions. NCV and 55 are level V expert opinion. studies are not reliable. Buschbacher59 15. Nagaoka M, Satou K: Tarsal tunnel References printed in bold type are syndrome caused by ganglia. J Bone Joint reported that the saphenous nerve those published within the past 5 Surg Br 1999;81(4):607-610. could not be elicited bilaterally in 25% years. 16. Takakura Y, Kitada C, Sugimoto K, of asymptomatic patients. Like other Tanaka Y, Tamai S: Tarsal tunnel entrapments, however, NCV studies 1. Singh G, Kumar VP: Neuroanatomical syndrome: Causes and results of operative basis for the tarsal tunnel syndrome. Foot treatment. 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Baxter DE, Thigpen CM: Heel pain: sion and neurolysis may be the preferred syndrome: Evaluation of surgical results Operative results. Foot Ankle 1984;5(1): options because neurectomy inevitably using multivariate analysis. Int Orthop 16-25. 1997;21(2):67-71. leads to permanent sensory deficits. 20. Davis PF, Severud E, Baxter DE: Painful 5. Radin EL: Tarsal tunnel syndrome. Clin heel syndrome: Results of nonoperative Orthop Relat Res 1983;181:167-170. treatment. Foot Ankle Int 1994;15(10): 531-535. Summary 6. Sammarco GJ, Chang L: Outcome of surgical treatment of tarsal tunnel 21. Recht MP, Grooff P, Ilaslan H, Recht HS, Entrapment neuropathies about the syndrome. Foot Ankle Int 2003;24(2): Sferra J, Donley BG: Selective atrophy of 125-131. the abductor digiti quinti: An MRI study. lower leg, ankle, and foot are uncom- AJR Am J Roentgenol 2007;189(3): 7. Kinoshita M, Okuda R, Morikawa J, W123-W127. mon but must be considered by the Jotoku T, Abe M: The dorsiflexion-eversion orthopaedic surgeons when treating test for diagnosis of tarsal tunnel syndrome. 22. Chundru U, Liebeskind A, Seidelmann F, patients with lower extremity pain. J Bone Joint Surg Am 2001;83(12): Fogel J, Franklin P, Beltran J: Plantar 1835-1839. fasciitis and calcaneal spur formation are Patients often present with chronic associated with abductor digiti minimi pain that has failed to respond to 8. Nagaoka M, Matsuzaki H: atrophy on MRI of the foot. Skeletal Radiol Ultrasonography in tarsal tunnel syndrome. 2008;37(6):505-510. nonsurgical management. A detailed J Ultrasound Med 2005;24(8):1035-1040. knowledge of the relevant anatomy is 23. Sinnaeve F, Vandeputte G: Clinical 9. Schon LC, Glennon TP, Baxter DE: Heel essential to establishing an accurate outcome of surgical intervention for pain syndrome: Electrodiagnostic support recalcitrant infero-medial heel pain. Acta diagnosis, followed by initiation of for nerve entrapment. Foot Ankle 1993;14 Orthop Belg 2008;74(4):483-488. appropriate treatment. Patients often (3):129-135. 24. Williams EH, Williams CG, Rosson GD, respond to nonsurgical measures; 10. Mullick T, Dellon AL: Results of Dellon LA: Anatomic site for proximal however, when these modalities fail to decompression of four medial ankle tunnels tibial nerve compression: A cadaver study. in the treatment of tarsal tunnels syndrome. Ann Plast Surg 2009;62(3):322-325. provide relief, surgical release should J Reconstr Microsurg 2008;24(2):119-126. be considered. The success of surgery 25. Williams EH, Rosson GD, Hagan RR, 11. 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