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Diabetic neuropathy is a major cause of morbidity among diabetics, usually affecting patients with long-standing diabetes and advancing age. We present a case of atypical first clinical presentation of type 1 diabetes mellitus (T1DM) in a pediatric patient. A 15-year-old male patient presented to the emergency department with complaints of right foot weakness associated with mild paresthesia of 1-week duration. There were complaints of polyuria, polydipsia and weight loss in the same timeframe. On subsequent examination, the patient exhibited signs of right-sided foot drop with weak ankle dorsiflexion and eversion, accompanied by impaired sensation over the dorsum of the right foot. Lab results confirmed a diagnosis of T1DM and the patient was started on subcutaneous insulin injections. The patient's foot drop recovered within one month of insulin initiation. This case highlights that T1DM may present atypically as acute onset neuropathy in pediatric patients, making it an important differential diagnosis. [ABSTRACT FROM AUTHOR]

Baxter's neuropathy is one of the overlooked causes of chronic heel pain. Diagnosing neuropathy in Baxter's can be challenging due to its potential occurrence as a secondary condition to other common syndromes that cause heel pain, such as plantar fasciitis, calcaneal spur, hypertrophic muscle, tenosynovitis, space-occupying lesions or trauma. Ultrasound is a reliable and easily accessible device that guides injections for the treatment of Baxter's neuropathy. We have written this letter as a guide, especially for beginner and professional pain specialists. [ABSTRACT FROM AUTHOR]

At the inner rear portion of the foot is a tunnel through which a nerve, blood vessel, and several tendons pass. As long as the foot and ankle function in a balanced manner, this tunnel and its neurovascular bundle create no problems. If, however, the ankle and foot become imbalanced in a particular and measurable way, the fibrous band that covers the tunnel becomes stretched and interferes with both normal nerve function and circulation. This area is known as the tarsal tunnel. A narrowing of the tunnel follows foot pronation, an extremely common human problem, which is an inward rolling of the ankle and foot. Unfortunately, when the problem first develops it usually does not cause symptoms. If symptoms such as pain or numbness developed immediately, the individual would recognise a problem and seek treatment. Manual muscle testing of the muscles that move the foot permits the earliest diagnosis of this oncoming problem to occur and saves many patients from enormous troubles. The muscular analysis offered by chiropractic manual muscle testing are the very muscles that help support the bones during activity to avoid narrowing of the tarsal tunnel. [ABSTRACT FROM AUTHOR]

Introduction: The anatomy of the forefoot is complex, and the sonographic assessment to image the plantar digital nerves and exclude, diagnose or discriminate between a Morton's neuroma and intermetatarsal bursitis can be challenging. Topic description and discussion: A good appreciation of the sonographic anatomy, technique, normal and abnormal appearances is required to undertake a sonographic assessment of the forefoot and its interspaces, particularly the plantar digital nerves. This is unpacked in this paper with associated pictorial aids. Muscles, tendons, and ligaments of the interspaces and the nearby metatarsophalangeal joints and their associated soft-tissue structures are helpful sonographic landmarks to guide imaging and assessment of the common and proper plantar digital nerves and the intermetatarsal bursa. These need to be appreciated from both dorsal and plantar sonographic approaches, in both short- and long-axis imaging planes. Conclusion: Improved understanding of the anatomy and sonographic appearances of the interspace structures can enhance the sonographic assessment of the forefoot and improve diagnosis of a Morton's neuroma and/or intermetatarsal bursitis when present to guide patient management. [ABSTRACT FROM AUTHOR]

Background:  Foot drop is the common endpoint for a diverse set of nerve injuries, affecting over 128,000 in the United States each year. The level of injury, finite pace of regeneration, and/ exponential decay in the percentage of motor end-plates reinnervated over time may explain the limited success with natural recovery. Past nerve techniques have also been met with limited success., Methods:  This narrative review explores why past nerve techniques have failed to correct foot drop., Results:  Previously described nerve transfer techniques suffer from incompletely balancing the foot and ankle, poor donor-target nerve synergy, and/or not effectively bypassing the wide and oftentimes underappreciated zone of injury. For maximal stability, one should look to balance the foot in both dorsiflexion and eversion. Detailed descriptions and illustrations of the branching anatomy for the peroneal and tibial nerves are provided, with specific application to nerve transfer reconstruction., Conclusion:  Based on an understanding of why past nerve techniques have failed to correct foot drop, a set of surgical principles can be codified to optimize functional outcomes. A surgical technique should be versatile enough to address foot drop from any of the three common pathways of injury (lumbar spine, sciatic nerve, and common peroneal nerve). With increasing familiarity using this once poorly understood anatomical region, limitations with past nerve transfer techniques may be overcome., Competing Interests: None declared., (Thieme. All rights reserved.)

Here, we present a protocol for staining murine skin innervation by either a pan-axonal marker or a genetic tracer of sensory neuron subtypes using floating sections. We also describe steps for using a new MATLAB-based semiautomated routine that facilitates the quantification of innervation density. This protocol can also be applied to other organs, such as the mouse's spinal cord and tongue. For complete details on the use and execution of this protocol, please refer to Dey et al. 1 ., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: We aimed to investigate the compression and ischemic effects of two different tourniquet pressures on tissues during surgery show a clinical difference., Methods: Patients aged 18-65 years who underwent foot and ankle surgery and applied a tourniquet in a single center between September 2022 and November 2023 were included in this prospective randomized study. Accordingly, tourniquet pressures were applied as limb occlusion pressure (LOP) + 50 mmHg in group 1 (12 patients) and LOP + 100 mmHg in group 2 (12 patients). The time point at which the femoral nerve motor evoked potential (MEP) decreased by 50%, the time point at which the MEP decreased by 100% for all nerves (femoral, tibial, and deep peroneal), and the time point at which all responses returned after the tourniquet was deflated were identified as the time points for analysis., Results: There were no differences in demographic data (age, body mass index, and sex) between the two groups. The mean tourniquet pressure was 191 ± 16 mmHg in Group 1 and 247 ± 21 mmHg in Group 2 (p < 0.001). A 50% decrease in the femoral nerve MEP value was observed at an average of 47 min in Group 1 and 34 min in Group 2 (p < 0.001). A complete loss of MEP responses for all nerves was observed at an average of 69 min in Group 1 and 56 min in Group 2. After the tourniquet was deflated, all MEP responses returned to baseline values at an average of 8.5 min in Group 1 and 12.6 min in Group 2 (p = 0.007). The results showed that lower limb nerve innervation was affected later and returned to normal earlier after deflation of the tourniquet in Group 1 (low tourniquet pressure group)., Conclusions: The innervations of the lower extremity nerves were affected later in the group in which low tourniquet pressure was applied (average 191 mmHg). Again, in this group (LOP + 50 mmHg), nerve conduction recovered an average of 10 min after deflation and four minutes earlier than in the high tourniquet pressure group., Level of Evidence: Level I, diagnostic study., Trial Registration: NCT05926154., (© 2024. The Author(s).)

Peripheral neuropathies of the foot and ankle can be challenging to diagnose clinically due to concomitant traumatic and nontraumatic or degenerative orthopedic conditions. Although clinical history, physical examination, and electrodiagnostic testing comprised of nerve conduction velocities and electromyography are used primarily for the identification and classification of peripheral nerve disorders, MR neurography (MRN) can be used to visualize the peripheral nerves as well as the skeletal muscles of the foot and ankle for primary neurogenic pathology and skeletal muscle denervation effect. Proper knowledge of the anatomy and pathophysiology of peripheral nerves is important for an MRN interpretation., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Vibrotactile stimulation has been studied in its efficacy of reducing freezing of gait (FOG) in patients with Parkinson's disease (PD). However, the results are still controversial. We evaluated the efficacy of a newly developed vibrotactile foot device on freezing severity and gait measures in PD patients with FOG., Objective: To evaluate the efficacy of vibrotactile foot device on PD patients with FOG., Methods: Thirty-three PD patients with FOG were examined during their "off" medication state. The efficacy of the vibrotactile foot device was evaluated using a gait protocol comprising walking trials with vibrotactile stimulation "off" and "on." Walking trials were videotaped for the offline rating by two movement disorder specialists. The Opal inertial sensor unit (128 Hz; Mobility Lab; APDM Inc., Portland, OR, USA) was used for quantitative gait analysis., Results: The results demonstrated 33.1% reduction in number of FOG episodes (P < 0.001) and 32.6% reduction of freezing episodes (P < 0.001). Quantitative gait analysis showed a significant increase in step length (P = 0.033). A moderate negative correlation was observed between the change of percent time frozen and age (r = -0.415, P = 0.016). 73% of participants reported minimal to substantial improvement in walking with this vibrating stimulation delivered by the vibrotactile foot device., Conclusions: The vibrotactile foot device is an efficient device that could significantly reduce freezing severity and provide gait regulation to patients with PD experiencing frequent freezing. It could potentially be used in the home environment for improving the quality of life., (© 2024 International Parkinson and Movement Disorder Society.)

Objective: The objective of this study was to optimize an MRI-based diffusion tensor imaging (DTI) protocol for imaging the plantar nerves at the level of the tarsus in normal equine limbs., Sample: 12 pelvic cadaver limbs from horses without evidence of proximal suspensory pathology were imaged with a 3T MRI system., Methods: For diffusion-weighted imaging, b values of 600, 800, and 1,000 s/mm2 were tested. Data were processed with DSI Studio. Cross-sectional areas of the medial and lateral plantar nerve along the plantar tarsus were recorded. The length and number of fiber tracts, signal-to-noise ratio, and DTI variables were recorded., Results: At the level of interest, the mean cross-sectional areas of the plantar nerves ranged from 5.03 to 7.42 mm2. The DTI maps consistently generated tracts in the region of the lateral and medial plantar nerves with DTI values in the range of values reported for peripheral nerves in humans. Our findings demonstrate that DTI of the medial and lateral plantar nerves can be performed successfully and used to generate quantitative parameters including fractional anisotropy and mean, axial, and radial diffusivity., Clinical Relevance: Quantitative data generated with this imaging technique can be used to noninvasively characterize the microstructural integrity of neural tissue with possible applications in the evaluation of pathologic changes to the plantar tarsal and metatarsal nerves of horses with proximal suspensory desmopathy.

Background and Objectives: This study aims to identify the precise anatomical location and therapeutic mechanisms of the KI1 acupoint (Yongquan) in relation to foot muscles and nerves, known for treating neurological disorders and pain. Materials and Methods: Dissection of six cadavers at Chungnam National University College of Medicine examined KI1's relation to the foot's four-layer structure. Results: The KI1 acupoint was located in the superficial and deep layers of the plantar foot, adjacent to significant nerves like the medial and lateral plantar nerves. Differences in the acupoint's exact location between genders were noted, reflecting variances in foot morphology. KI1 acupuncture was found to stimulate the muscle spindles and nerve fibers essential for balance and bipedal locomotion. This stimulation may enhance sensory feedback, potentially improving cognitive functions and balance control. Conclusions: This anatomical insight into KI1 acupuncture underpins its potential in neurological therapies and pain management.

Background: Sleep disturbances, which are common problems in older adults, often lead to cognitive decline and depression and may even increase mortality risk. Foot thermal therapy is a simple and safe approach for improving sleep and is associated with relatively few side effects. However, the effect of different operations of foot thermal therapy on sleep quality in older adults is inconclusive. This study aimed to access the effects of temperature, duration, and heating height of foot thermal therapy (administered through a footbath) on the subjective and objective sleep quality of older adults. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline, eight databases were searched for all relevant articles published up to July 2023, and a rigorous systematic review and meta-analysis was conducted. This study was registered in the PROSPERO database (CRD42022383460). Inclusion criteria were: (1) participants with a mean age ≥60 years; (2) interventions that included foot thermal therapy; (3) a control group that received routine care but no thermal therapy; (4) outcome measurements that assessed sleep quality; and (5) the studies that utilized randomized controlled trials or quasi-experimental studies. Methodological quality was assessed using the Joanna Briggs Institute critical appraisal tools. The meta-analysis was performed using RevMan version 5.4. Results: A total of 11 studies were included. Foot thermal therapy before bedtime improved subjective sleep quality in older adults, with optimal parameters of 40°C temperature (standardized mean difference [SMD] = 0.66, 95% confidence interval [CI]: 0.33 to 0.99), ≤20-min duration (SMD = 0.66, 95% CI: 0.39 to 0.93), and 10 cm heating height (SMD = 0.78, 95% CI: 0.45 to 1.11). Subgroup analyses revealed that a temperature of 41°C-42°C can improve objective sleep latency (SMD = 0.54, 95% CI: 0.09 to 0.99). Conclusions: It is recommended to administer foot thermal therapy (40°C; ≤20 min; 10 cm above the ankle) to older adults 1 h before their bedtime. If they have trouble falling asleep, the temperature can be increased to 41°C-42°C.

Huangqi Guizhi Wuwu Decoction (HGWD) is a classic traditional Chinese herbal formula from " Synopsis of Golden Chamber ," which is used to treat blood stagnation and has been used for alleviating diabetic peripheral neuropathy (DPN) in the clinic. However, the mechanisms of HGWD intervention DPN are still to be discovered. This study aims to explore the mechanism of HGWD intervention DPN by integrating plasma metabolomics and gut microbiome. BKS Cg- m +/+ Lepr db /J (db/db) mice with DPN were at 16 weeks of age. The indices of DPN phenotypes in db/db mice, pathomorphology of the sciatic nerve, intraepithelial nerve fibers (IENF) of the foot pad, levels of blood lipids and oxidative stress, and inflammatory reaction were used to appraise the HGWD efficacy. Finally, the pharmacological mechanisms of HGWD intervening DPN were explored by metabolomics and 16S rRNA gene sequencing. HGWD reversed DPN phenotypes in db/db mice, improved peripheral nerve structure, ameliorated the level of blood lipids and nerve growth factor in plasma, enhanced antioxidant capacity, and alleviated inflammatory responses. Plasma metabolomics disclosed that HGWD remarkably regulated the unusual levels of thirty-seven metabolites involved in sphingolipid metabolism, biosynthesis of unsaturated fatty acids, arachidonic acid metabolism, and amino acid biosynthesis pathways. The gut microbiome showed that nine bacteria were highly correlated with the efficacy of HGWD in DPN. Integrating analysis of microbiome and metabolomics demonstrated that the interaction of four bacteria with four metabolic pathways might be the significant mechanism of HGWD intervention in DPN. The mediation of gut microbiota and plasma metabolism may be the potential mechanism of HGWD ameliorating DPN in db/db mice. The interaction of Lactobacillus , Alloprevotella , Bacteroides , and Desulfovibio with four metabolic pathways might be the critical mechanism for HGWD treating DPN. [Display omitted] • The mechanism of HGWD intervention DPN was studied for the first time by combining metabolomics and microbiomics. • HGWD can ameliorate the phenotype of DPN. • The interaction of four bacteria with four metabolic pathways might be the critical mechanism for HGWD treating DPN. [ABSTRACT FROM AUTHOR]

Background: Denervation is a surgical option in ankle arthrosis when conservative therapy has failed. Sectioning all joint branches is essential for its success. The locations of the articular branches of the saphenous (Sa), tibial (Ti), sural (Su), superficial (Ps) and deep peroneal (Pp) nerves are specified., Methods: In 16 cryopreserved specimens, the courses of the nerves were prepared. Their articular branches were identified, and their respective locations documented by using a new reference system., Results: The articular branches to the ankle ranged from 5 to 30 cm measured from the foot sole. The Sa should be transected at 22.5 cm, the Su at 20 cm, and the Pp at 15 cm. The Ti should be skeletonized up to 25 cm. Epifascial dissection of the Ps is to be performed below 15 cm., Conclusion: The study specifies the joint branches of the ankle in an intraoperatively reproducible reference system and thus minimizes the required skin incisions., Competing Interests: Declaration of interest None., (Copyright © 2023 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

Background: The heel is a complex anatomical region and is very often the source of pain complaints. The medial heel contains a number of structures, capable of compressing the main nerves of the region and knowing its anatomical topography is mandatory. The purpose of this work is to evaluate if tibial nerve (TN) and its main branches relate to the main anatomical landmarks of the ankle's medial side and if so, do they have a regular path after emerging from TN., Methods: The distal part of the legs, ankles and feet of 12 Thiel embalmed cadavers were dissected. The pattern of the branches of the TN was registered and the measurements were performed according to the Dellon-McKinnon malleolar-calcaneal line (DML) and the Heimkes Triangle (HT)., Results: The TN divided proximal to DML in 87.5%, on top of the DML in 12,5% and distal in none of the feet. The Baxter's nerve (BN) originated proximally in 50%, on top of the DML in 12,5% and distally in 37.5% of the cases. There was a strong and significant correlation between the length of DML and the distance from the center of the medial malleolus (MM) to the lateral plantar nerve (LPN), medial plantar (MPN) nerve, BN and Medial Calcaneal Nerve (MCN) (ρ: 0.910, 0.866, 0.970 and 0.762 respectively, p <  0.001)., Conclusions: In our sample the TN divides distal to DML in none of the cases. We also report a strong association between ankle size and the distribution of the MPN, LPN, BN and MCN. We hypothesize that location of these branches on the medial side of the ankle could be more predictable if we take into consideration the distance between the MM and the medial process of the calcaneal tuberosity., (© 2023. The Author(s).)

Purpose: There are no data on the connection of the saphenous nerve (SN), located on the medial side of the foot, with the terminal branches of the superficial fibular nerve. The aim of this study is to reveal the variation that surgeons should pay attention to for anesthesia applied in foot surgeries., Methods: In this study, the left foot of a 70-year-old female cadaver fixed with formalin was dissected. The distance to the medial malleolus and the incision line was recorded using digital caliper to determine the reference points in the resulting variation., Results: It was observed that a branch from the SN, which arose from the SN and proceeded anteriorly to the upper part of the medial malleolus and continued towards the dorsum of the foot, hooked with a branch from the medial dorsal cutaneous nerve (MDCN). The branches arising from this hook were distributed on the medial edge of the foot up to the proximal metatarsophalangeal joint I. The distance of this nerve connection to the medial malleolus is 91.14 mm, and the distance to the incision line is 15.76 mm., Conclusions: It is suggested that the case presented as an unusual SN variation, which may affect the success of local anesthesia in invasive procedures to the medial part of the foot and could be considered in the evaluation of sensory loss after anteromedial surgical approach to the ankle, should be included in the classification of the cutaneous innervation pattern of the foot., (© 2023. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Summary: The tibial nerve is bound tightly to the posterior tibial artery in the tarsal tunnel where expansion capacity is limited. Therefore, the nerve may be vulnerable to, and damaged by chronic pulsatile trauma from an atypically positioned overriding artery, labeled "punched-nerve syndrome". In this article, we present a 49-year-old woman who presented with two months of severe burning pain in the left medial ankle and sole of the foot without antecedent trauma. Neurological examination identified dysesthetic sensation to light touch in the left medial sole of the foot, and both active and passive dorsiflexion worsened the painful paresthesia. Nerve conduction studies demonstrated a reduced left medial plantar mixed nerve action potential amplitude, 50% less than the right. High-resolution ultrasound (HRUS) showed an increased left tibial nerve cross-sectional area of 26 mm2 (normal <22.3 mm2) at the level of the ankle with side-to-side difference of 6 mm2 (normal <5.7 mm2). The distal tibial nerve and its medial plantar branch were atypically positioned immediately deep to the left posterior tibial artery and abnormally flattened with focal enlargement of the nerve on longitudinal view. Dynamic analysis demonstrated the nerve being compressed with each pulsation of the tibial artery immediately above. Active dorsiflexion of the ankle narrowed the space underneath the flexor retinaculum resulting in further compression of the nerve against the artery. In conclusion, HRUS as an adjunct to electrophysiological studies identified punched-nerve arterial compression as an etiology of tarsal tunnel syndrome., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2022 by the American Clinical Neurophysiology Society.)

Introduction/Purpose: The lateral dorsal cutaneous nerve (LDCN) and anastomotic branch to the intermediate dorsal cutaneous nerve (AICN) can be injured during foot and ankle surgery. Cadaveric specimen studies are limited by small sample size.1-11 We sought to use high-field 3-tesla (3T) magnetic resonance imaging (MRI) to examine a significantly larger cohort and obtain a more representative sample of the course of the LDCN and AICN. A more generalizable understanding of the course and position of these structures will aid surgeons intraoperatively in avoiding iatrogenic injury when performing the sinus tarsi approach, as well as during percutaneous intramedullary fixation of the 5th metatarsal. Methods: High-field 3T MRI studies performed between January 2015 to January 2020 were reviewed. Three blinded reviewers at a single academic center measured the coronal distances of LDCN and AICN from the fifth metatarsal styloid (5MS). Intraclass correlation coefficients (ICC) were calculated to assess reviewer reliability. Foot and ankle MRIs with major structural abnormalities, such as tumor or the presence of hardware, were excluded. Results: A total of 125 foot and ankle 3T MRIs were identified. Intraclass correlation coefficient was excellent at 0.87 for LDCN to 5MS and 0.88 for AICN to 5MS. The mean distance of the LDCN to the 5MS was 0.8 cm (range 0.3-1.4 cm, CI 0.8-0.8 cm) and that from the AICN to the 5MS was 2.1 cm (range 1.6-3.2 cm, CI 2.0-2.2 cm. Height had no significant correlation with the nerves' distance from bony landmarks with r values of 0.14 and 0.29 for the LDCN and AICN, respectively. Similarly, we did not find BMI to significantly correlate, with r values of 0.10 and 0.30 for the LDCN and AICN, respectively. Conclusion: Our study demonstrated the LDCN and AICN can be found on average 0.8 cm and 2.1 cm, respectively, above the 5MS with no clear association to patient height or BMI. Literature studying the range of distances the LDCN is found from the 5MS is scarce, but one study noted the range to be 0.7-1.2 cm, which is significantly smaller than our range of 0.3-1.4 cm.3 To our knowledge, our study is first to note the range of distances the AICN can be found from the 5MS, which is 1.6-3.2 cm. [ABSTRACT FROM AUTHOR]

Considerable variations have been reported regarding the branching pattern of tibial nerve (TN) close to its termination in foot. In order to comprehend the clinical anatomy of heel pain awareness of all the possible variations in relation to terminal branching pattern of TN (close to the tarsal tunnel) is essential. The present study was conducted to undertake a comprehensive review of the variations in TN branches in foot with particular emphasis on the implications for sensory distribution of these branches. Articles were searched in major online indexed databases using relevant key words. The pattern of termination of TN was noted as either trifurcation or bifurcation. Bifurcation pattern was more commonly observed and is associated with the medial calcaneal nerve (MCN) either arising high or low relative to the tarsal tunnel. The most commonly noted type of bifurcation was proximal to malleolar-calcaneal axis but within the tarsal tunnel. Across all five types of bifurcation reported in literature, the termination points of TN ranged from 3 cm proximal to 3 cm distal to malleolar-calcaneal axis and, therefore, the area beyond this region can be considered as safe zone for performing invasive procedures. MCN showed considerable variations in its origin both in trifurcation and bifurcation pattern pertaining to number of branches (one/two/three) at the point of origin. The origin of inferior calcaneal nerve was observed to be relativelyless variable as it mostly arose as a branch of lateral plantar nerve and sometimes as a direct branch from TN before termination. The frequent variation of MCN in the tarsal tunnel should be kept in mind while undertaking decompression measures in medial ankle region.

Background: Tarsal tunnel syndrome (TTS) is typically caused by an anatomical variant or mechanical compression of the tibial nerve (TN) with variable success after surgical treatment., Method: 40 lower-leg specimens were obtained. Dissections were appropriately conducted. Extremities were prepared under formaldehyde solution. The tibial nerve and branches were dissected for measurements and various characteristics., Results: The flexor retinaculum had a denser consistency in 22.5% of the cases and the average length was 51.9 mm. The flexor retinaculum as an independent structure was absent and 77.2% of cases as an undistinguished extension of the crural fascia. The lateral plantar nerve (LPN) and abductor digiti minimi (ADM) nerve shared same origin in 80% of cases, 34.5% bifurcated proximal to the DM (Dellon-McKinnon malleolar-calcaneal line) line 31.2% distally and 34.3% at the same level., Conclusion: Understanding the tibial nerve anatomy will allow us to adapt our surgical technique to improve the treatment of this recurrent pathology., Competing Interests: Declaration of interest None., (Copyright © 2022 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

Objective: To explore safety and accuracy of four-point acupotomy for the treatment of tarsal tunnel syndrome regarding release of ankle tunnel flexor retinaculum to provide an anatomical basis of clinical treatment., Methods: Twenty-nine adult specimens (15 males and 14 females) fixed with 10% formalin, aged from 47 to 98 years old with an average age of (81.10±11.14) years old, 29 on the right side and 29 on the left side, which were selected for the study from September 2020 to October 2020. Simulate the operation of loosening flexor retinaculumt with a needle knife on the human specimen, and place the specimen on the frog position of lower limbs with medial malleolus upward to determine the center of medial malleolus. Choose 4 different positions near the flexor retinaculum to insert the needle so that the needle body was perpendicular to skin and cutting edge direction was perpendicular to the running direction of the flexor retinaculum. The needle knife penetrates the skin and explores slowly. When the flexor retinaculum was reached, the needle tip may touch the tough tissue. At this time, the cutting is loosened for 4 times. After acupotomy release operation was completed, make a lateral incision on the skin surface along acupotomy direction, open the area of the exposed flexor retinaculum, dissecting layer by layer, observe and record the needle knife and its surrounding anatomical structure. The length of acupotomy cutting marks of flexor retinaculum was measured by electronic vernier caliper. The safety and accuracy of acupotomy loosening of ankle canal flexor retinaculum were evaluated by observing the number and degree of ankle canal contents such as tendons and nerves injured by needle knife. The safety is to count the number of cases of acupotomy injury to the contents of the ankle canal, and to calculate the injury rate, that is, the number of injury cases/total cases × 100%. The effective release was defined as the release length L ≥ W/2(W is the width of the flexor retinaculum, defined as 20 mm)., Results: For safety, there were no acupotomy injuries to nerves or blood vessels in 58 cases, 26 cases injuried to posterior tibial tendon which 17 of these tendon injury cases, the tendon was penetrated and severely injured, and flexor digitorum longus tendon was injured in 12 cases. Among these cases, tendon was penetrated and severely injured in 4 cases, and total injury rate was 32.14%. No nerve and vessel injury on c3 and c4 point. For accuracy, 58 specimens were successfully released. The length Lc of releasing trace for acupotomy was (10.40±1.36) cm, and length range 6.38 to 12.88 cm. Among all cases, the length of releasing trace was ≥10 mm in 37 cases. The overall success rate of release was 100.00%. Layered structure of ankle tube flexor retinaculumt:fiber diaphragm from flexor retinaculum divides contents of ankle tube into different chambers inward, and fiber diaphragm meets here to synthesize a complete flexor retinaculum at the midpoint of the line between the medial malleolus tip and calcaneal tubercle(above the neurovascular course)., Conclusion: Four-point needle-knife method of releasing flexor retinaculum for the treatment of tarsal tunnel syndrome is performed at the attachment of the two ends of flexor retinaculum;the tendon, but not the nerves and blood vessels, is easily damaged. It is safe to insert needle on the side of calcaneus. The extent of release is relatively complete, but due to the "layered" structure of the flexor retinaculum, classic surgical technique could only release one layer of flexor retinaculum when a needle is inserted at the edge of the bone and cannot achieve complete release of the full thickness of the flexor. Therefore, it remains to be determined whether the desired effect can be achieved clinically.

The nerves in the skin surface of the foot are comprised of unmyelinated smaller somatic nerves and larger myelinated sensory nerves. Current diagnostic methods are unable to evaluate combined nerve conduction velocity (NCV) from both unmyelinated smaller somatic nerve (USSN) and myelinated larger nerves (MLN) respectively. Computational models may provide an alternative tool to determine the NCV of the combined nerve. Therefore, a combined functional dorsal nerve model (CFDNM) of the various dorsal nerves along with its associated nerve ending of the human foot is proposed and constructed. The combined dorsal nerve model consists of synthetic USSN (SUSSN) and dorsal MLN of the foot. The unmyelinated as well as myelinated electrophysiological nerve models were used to simulate selected SUSSN and MLN of the foot by injecting an external stimulus at the most distal part of SUSSN of the foot through the use of bidomain model. Results from our work demonstrated that the action potential propagated from the most distal part to proximal part of distinct dorsal nerves of the foot, e.g., the simulated NCV of the combined intermediate dorsal cutaneous nerve (IDCN) of the foot was 28.4 m s -1 . The CFDNM will provide a vital tool for diagnosis initially small fibre neuropathy (SFN) by computing NCV in the prospective studies.