Anatomical study of the distal course of the posterior tibial artery: A cadaver study.

OBJECTIVE: This study aimed to describe the course, branches, and variances of the posterior tibial artery, which provides the arterial supply of the plantar surface of the foot, starting from the tarsal tunnel level to provide descriptive information for all surgical interventions, diagnostic radiological procedures, and promising endovascular therapies in the tarsal region. METHODS: In this study, a dissection of 48 feet was performed on 25 formalin-fixed cadavers (19 males and 6 females). Surgical instruments and a digital caliper were used for dissection and measurements, and the critical structures were recorded by a Canon 250D camera to be illustrated later. RESULTS: All parameters were significantly longer in male cadavers compared to females. According to the correlation analysis, while there was a significant and robust correlation between the axial line and pternion-deep plantar arch (R=.830, P .05), a moderate correlation was found between the axial line and sphyrion-bifurcation (R=.575; P < .05), axial line and deep plantar arch-2nd interdigital commissure (R=.457; P < .05), and sphyrion-bifurcation and pternion-deep plantar arch (R=.480; P < .05). Variation in any branch of the posterior tibial artery was observed in 27 of the 48 studied sides. CONCLUSION: In our study, the branching and variability of posterior tibial artery on the plantar surface of the foot were described in detail with the determined parameters. In conditions that cause tissue and function loss and require reconstruction, such as diabetes mellitus and atherosclerosis, the most critical factor in increasing treatment success is a better understanding of the region's anatomy.

Proximity of percutaneous tibial nerve stimulation needle insertion to surrounding anatomic structures: a cadaveric study.

BACKGROUND: Percutaneous tibial nerve stimulation is a third-line treatment for overactive bladder and urgency urinary incontinence. During the procedure, a needle is inserted cephalad to the medial malleolus and posterior to the tibia. In recent years, permanent implants and leads have been developed for insertion into the medial ankle via a small incision. There are many important structures present in the medial compartment of the ankle, including the great saphenous vein, saphenous nerve, tibial nerve, posterior tibial vessels, and tendons of the posterior compartment leg muscles. OBJECTIVE: The primary objective of this study was to identify the proximity of the percutaneous tibial nerve stimulation needle placed per Food and Drug Administration-approved device instructions to nearby important anatomic structures. The secondary objectives were to identify the proximity of the tibial nerve to the needle site, identify clinically relevant ankle anatomic structures, and confirm the tibial nerve and posterior tibial vasculature by histologic analysis. STUDY DESIGN: Detailed medial ankle dissections were performed bilaterally on 10 female lightly embalmed anatomic donors (cadavers) obtained from the Willed Body Program at the University of Louisville. A pin was inserted at the percutaneous tibial nerve stimulation needle site, and the medial ankle was minimally dissected so the surrounding anatomic structures were visible but not disrupted. The shortest distance from the pin to the selected structures of the medial ankle region was measured. On completion of each dissection and set of measurements, tissue was harvested for histologic examination. The distances between the pin and each structure were assessed using means and standard deviations. A paired t test was used to assess the difference in the locations between the left and right ankles. Statistical analysis was performed on left-sided, right-sided, and combined measurements. An 80% prediction interval was found to represent the expected range of values for the measurement of a new cadaver or patient, and the 95% confidence interval of the mean was computed to characterize the average distance across all cadavers or patients. RESULTS: The medial ankle of 10 adult female lightly embalmed cadavers were examined bilaterally. Dissections were completed from October 2021 to July 2022. Of note, 80% prediction intervals for the tibial nerve, the posterior tibial artery or vein, and the flexor digitorum longus tendon had a lower range of 0.0 mm from the pin and extending to 12.1, 9.5, and 13.9 mm, respectively. Moreover, 2 of the structures were found to be asymmetrical between the right and left ankles. The great saphenous vein was further from the pin on the left (20.5 mm [standard deviation of 6.4 mm] on the left vs 18.1 mm [standard deviation of 5.3 mm] on the right; P=.04). The calcaneal (Achilles) tendon was further from the pin on the right side (13.2 mm [standard deviation of 6.8 mm] vs 7.9 mm [standard deviation of 6.7 mm]; P=.04). Tibial neurovascular structures were confirmed with microscopic analysis. CONCLUSION: The anatomic structures within the medial ankle lie unexpectedly close to the percutaneous tibial nerve stimulation needle site as noted per Food and Drug Administration-approved device instructions. There is a possibility that some medial ankle structures are not symmetrical. It is crucial that practitioners understand medial ankle anatomy when performing percutaneous tibial nerve stimulation or permanent device insertion.

Variations in the branching pattern of tibial nerve in foot: a review of literature and relevant clinical anatomy.

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.

A novel categorization of the muscular branches of the tibial nerve within the popliteal fossa.

BACKGROUND: The muscular branches of the tibial nerve within the popliteal fossa innervate the gastrocnemius, soleus, plantaris, and popliteus muscles. Various branching patterns have been described in textbooks; however, the underlying fundamental rules explaining the patterns remain unclear. Understanding the fundamental rule explaining the branching pattern of the innervating nerves is essential for understanding the ontogeny of skeletal muscles. Therefore, this study aimed at establishing a theory to explain the branching pattern of the muscular branches of the tibial nerve within the popliteal fossa. METHODS: The branching patterns of the muscular branches of the tibial nerve within the popliteal fossa were examined macroscopically in 62 lower limbs derived from 31 adult cadavers (22 males and 9 females, aged 49-95 years). RESULTS: The branch to the medial head of the gastrocnemius muscle invariably arose from the posteromedial side of the tibial nerve. The branches to the soleus muscle and lateral head of the gastrocnemius muscle had a common trunk in all the lower limbs and invariably arose from the posterolateral side. The branches to the plantaris and popliteus muscles arose anteriorly from the tibial nerve in this order (plantaris branch first, followed by the popliteus branch). These branches invariably arose more distally than the branch to both the heads of the gastrocnemius and soleus muscles. CONCLUSIONS: Based on these fundamental branching patterns, we suggest a novel branching categorization. The branches could be categorized into a posterior group and an anterior group, which has independent branches to the plantaris and popliteus muscles. This fundamental branching pattern and novel categorization contribute to the understanding of the ontogeny of the skeletal muscles around the flexor compartment of the leg.

An anatomical study of the tibial nerve branches innervating the posterior tibial artery.

The arteries of the lower limbs are innervated by vascular branches (VBs) originating from the lumbar sympathetic trunk and branches of the spinal nerve. Although lumbar sympathectomy is used to treat nonreconstructive critical lower limb ischemia (CLLI), it has limited long-term effects. In addition, the anatomical structure of tibial nerve (TN) VBs remain incompletely understood. This study aimed to clarify their anatomy and better inform the surgical approach for nonreconstructive CLLI. Thirty-six adult cadavers were dissected under surgical microscopy to observe the patterns and origin points of VBs under direct vision. The calves were anatomically divided into five equal segments, and the number of VB origin points found in each was expressed as a proportion of the total found in the whole calf. Immunofluorescence staining was used to identify the sympathetic nerve fibers of the VBs. Our results showed that the TN gave off 3-4 VBs to innervate the posterior tibial artery (PTA), and the distances between VBs origin points and the medial tibial condyle were: 24.7 ± 16.3 mm, 91.7 ± 66.1 mm, 199.6 ± 52.0 mm, 231.7 ± 38.5 mm, respectively. They were mainly located in the first (40.46%) and fourth (31.68%) calf segments, and immunofluorescence staining showed that they contained tyrosine hydroxylase-positive sympathetic nerve fibers. These findings indicate that the TN gives off VBs to innervate the PTA and that these contain sympathetic nerve fibers. Therefore, these VBs may need to be cut to surgically treat nonreconstructable CLLI.

Sonographic peripheral nerve cross-sectional area in adults, excluding median and ulnar nerves: A systematic review and meta-analysis.

INTRODUCTION/AIMS: Although electromyography remains the "gold standard" for assessing and diagnosing peripheral nerve disorders, ultrasound has emerged as a useful adjunct, providing valuable anatomic information. The objective of this study was to conduct a systematic review and meta-analysis evaluating the normative sonographic values for adult peripheral nerve cross-sectional area (CSA). METHODS: Medline and Cochrane Library databases were systematically searched for healthy adult peripheral nerve CSA, excluding the median and ulnar nerves. Data were meta-analyzed, using a random-effects model, to calculate the mean nerve CSA and its 95% confidence interval (CI) for each nerve at a specific anatomical location (= group). RESULTS: Thirty groups were identified and meta-analyzed, which comprised 16 from the upper extremity and 15 from the lower extremity. The tibial nerve (n = 2916 nerves) was reported most commonly, followed by the common fibular nerve (n = 2580 nerves) and the radial nerve (n = 2326 nerves). Means and 95% confidence interval (CIs) of nerve CSA for the largest number of combined nerves were: radial nerve assessed at the spiral groove (n = 1810; mean, 5.14 mm2 ; 95% CI, 4.33 to 5.96); common fibular nerve assessed at the fibular head (n = 1460; mean, 10.18 mm2 ; 95% CI, 8.91 to 11.45); and common fibular nerve assessed at the popliteal fossa (n = 1120; mean, 12.90 mm2 ; 95% CI, 9.12 to 16.68). Publication bias was suspected, but its influence on the results was minimal. DISCUSSION: Two hundred thirty mean CSAs from 15 857 adult nerves are included in the meta-analysis. These are further categorized into 30 groups, based on anatomical location, providing a comprehensive reference for the clinician and researcher investigating adult peripheral nerve anatomy.

Mapeo sonográfico de los nervios de la cara medial del tobillo y del pie / Sonographic mapping of the nerves of the medial side of the ankle and foot

El uso de los ultrasonidos en el examen, la identificación y el intervencionismo de las diferentes ramas nerviosas del tobillo y del pie son una herramienta de gran apoyo en el ámbito clínico. En la actualidad, la ecografía es un método que se ha ido universalizando en el mundo de la podología, bien por su mayor accesibilidad debido al abaratamiento de los costes, a los avances tecnológicos y a sus beneficios de inocuidad, fácil disponibilidad para el examen inmediato y su aplicación dinámica en la evaluación de las diferentes estructuras anatómicas. El presente trabajo trata de presentar a la comunidad podológica una descripción detallada del mapeo mediante ecografía de los nervios en cara medial del pie. Entendemos que esta descripción puede ayudar a los profesionales en el diagnóstico de las patologías de atrapamiento nervioso a dicho nivel, así como en procedimientos mínimamente invasivos guiados ecográficamente en dicha área anatómica.(AU)

The use of ultrasound in clinical practice is a great tool for the examination, identification and intervention of the different nerve branches in the foot and ankle. Nowadays, sonography is an exploratory method that has been universally expanded in podiatry because of lowering of costs associated to its use, technological progresses and its benefits of safety, disposal for the inmediate clinical exam and its dynamic application in the evaluation of different structures. The aim of the present paper is to present to the podiatry community a detailed description of sonographic mapping of the nerves in the medial side of the ankle. It is intended to help professionals involved in the management of foot ankle disorders regarding the diagnosis of entrapment neuropathies at this level and also to help with minimally invasive treatments sonographically guided.(AU)

The interosseus crural nerve: An anatomical study of a rarely described structure.

The interosseous crural nerve (IOCn) is said to arise distally from muscular branches of the tibial nerve innervating the deep muscles of the posterior compartment of the leg. Here, we present the results of a cadaveric study of the IOCn to clarify this nerve's morphology and to discuss its potential clinical relevance. On 26 sides from 13 cadaveric specimens, the IOCn was dissected. The IOCn was identified on 14 out of 26 sides (53.8%). The mean diameter and length of the IOCn were 0.46 mm (range 0.3-0.72 mm) and 20.9 mm (range 13.5-33.0 mm), respectively. The origin of the IOCn was from a branch to the popliteus muscle on all sides. The nerve was found to have vascular, muscular, and ligamentous branches. In 53.8%, the nerve reached the inferior tibiofibular joint, and in 46.2%, the nerve terminated in the interosseous membrane of the leg. At its distal part, the IOCn gave off multiple vascular branches to the fibular artery. On one side (7.1%), the nerve pierced the interosseous membrane and innervated muscles of the anterior compartment of the leg. We believe this to be the first anatomical study of the IOCn. The nerve was found to have vascular, muscular, and ligamentous branches. Surgeons operating in the deep posterior compartment of the leg and ankle and clinicians treating patients with unusual presentations or pathology of the leg and ankle should be aware of this structure.

Nerve and Arterial Supply Pattern of the Popliteus Muscle and Clinical Implications.

INTRODUCTION: The aim of this study was to investigate the nerve and artery supply and the tibial attachment of the popliteus muscle using anatomical methods. METHODS: Forty-four nonembalmed and embalmed extremities were dissected for this study. To measure the attachment area of the popliteus, the most prominent points of the medial epicondyle of the femur and the medial malleolus of the tibia were identified before dissection. A line connecting these two prominent points was used as the reference line, with the most prominent point of the medial epicondyle of the femur as the starting point. This study also investigated the area where the popliteus attaches to the bone and the points where nerves and arteries enter the popliteus muscle when it is divided into three equal parts in the coronal plane. RESULTS: The mean length of the reference line was 34.6 ± 2.1 cm. The origin of the popliteus was found to be at a distance of 16.6% to 35.2% on the tibial bone from the proximal region. The popliteus was innervated by only the tibial nerve in 90% of the cases and by the tibial and the sciatic nerves in the remaining 10% of the cases. The inferior medial genicular artery and the posterior tibial artery supplied blood to the popliteus in 90% and 65% of the cases, respectively. When the popliteus muscle was divided into three equal parts in the coronal plane, the nerve and the artery were found to enter the muscle belly in zones II and III and zones I and II in 92% and 98% of the specimens, respectively. Discussion. The anatomical investigation of the popliteus in this study will help identify patients with clinically relevant syndromes.

Biometría del nervio para el músculo sóleo y sus implicancias clínicas / Nerve biometry for the soleus muscle and its clinical implications

RESUMEN: Las lesiones del nervio fibular común y/o sus ramos derivados trae como consecuencia, pérdida total o parcial de la capacidad para realizar flexión dorsal del complejo tobillo-pie, una opción viable para tratar esta patología es la transferencia nerviosa, que consiste en utilizar un nervio donante para restaurar la función de un nervio dañado. Es frecuente la utilización del nervio para el músculo sóleo (NS) como donante para restaurar la función del nervio fibular común o profundo, por lo cual es indispensable conocer en detalle la anatomía de este nervio. Se utilizaron 22 miembros inferiores pertenecientes a las Unidades de Anatomía de las Universidades de Chile y de Santiago, Chile. Se realizó disección del nervio para el músculo sóleo, se observó número de ramos principales y secundarios, así como también se registró su origen y la longitud de ellos, además se dividió a la pierna en cuadrantes para determinar la localización de los puntos motores. El nervio para el músculo sóleo en la mayoría de los casos (95,4 %) es único y se origina desde el nervio tibial o en tronco común con otro ramo muscular. La distancia promedio entre el origen de NS y la línea biepicondilar fue de 28,77 mm; la longitud promedio de NS hasta su división en ramos secundarios o penetración directa fue de 52 mm. El NS se dividió en ramos secundarios (RS), observándose que en 12 casos fue en 2 RS, en 3 casos en 3 RS y en 7 casos no hubo RS. Los puntos motores se localizaron en el quinto proximal de la pierna, 23 casos en el primer cuadrante lateral y 4 casos en el primer cuadrante medial; en el cuarto proximal de la pierna, 7 casos en el segundo cuadrante lateral y 4 casos en el segundo cuadrante medial. Los datos obtenidos serán un aporte al conocimiento anatómico y a la cirugía reconstructiva de los nervios de la región.

SUMMARY: Injuries to the common fibular nerve and/or its derived branches result in total or partial loss of the ability to dorsiflex the ankle-foot complex. A viable option to treat this pathology is nerve transfer, which consists of using a donor nerve to restore function to a damaged nerve. The use of the nerve for the soleus muscle (SN) is frequent as a donor to restore the function of the common or deep fibular nerve, for which it is essential to know in detail the anatomy of this nerve. Twenty-two lower limbs belonging to the anatomy units of the Universities of Chile and Santiago were used. Dissection was performed until the SN was reached, the number of main and secondary branches (SB) was observed, as well as their origin and length, and the leg was divided into quadrants to determine the location of the motor points. The SN in most cases (95.4 %) is unique and originates from the tibial nerve or from the common trunk with another muscular branch. The average distance between the origin of the NS and the biepicondylar line was 28.77 mm; the average length of NS until its division into SB or direct penetration was 52 mm. The NS was divided into SB, observing that in 12 cases it was in 2 branches, in 3 cases in 3 branches and in 7 cases there were no SB. The motor points were located in the proximal fifth of the leg, 23 cases in the first lateral quadrant and 4 cases in the first medial quadrant; in the proximal quarter of the leg, 7 cases in the second lateral quadrant and 4 cases in the second medial quadrant. The data obtained will be a contribution to anatomical knowledge and reconstructive surgery of the nerves of the region.

An MRI study of the tibial nerve in the ankle canal and its branches: a method of multiplanar reformation with 3D-FIESTA-C sequences.

BACKGROUND: The visualization of the tibial nerve and its branches in the ankle canal is helpful for the diagnosis of local lesions and compression, and it is also useful for clinical observation and surgical planning. The aim of this study was to investigate the feasibility of three-dimensional dual-excitation balanced steady-state free precession sequence (3D-FIESTA-C) multiplanar reformation (MPR) display of the tibial nerve and its branches in the ankle canal. METHODS: The subjects were 20 healthy volunteers (40 ankles), aged 22-50 years, with no history of ankle joint disease. The 3D-FIESTA-C sequence was used in the 3.0 T magnetic resonance equipment for imaging. During scanning, each foot was at an angle of 90° to the tibia. The tibial nerve of the ankle canal and its branches were displayed and measured at the same level through MPR. RESULTS: Most of the tibial nerve bifurcation points were located in the ankle canal (57.5%), few bifurcation points (42.5%) were located at the proximal end of the ankle canal, and none of them were found away from the distal end. The bifurcation between the medial plantar nerve and the lateral plantar nerve was on the line between the tip of the medial malleolus and the calcaneus, and it's angle ranged between 6° and 35°. In MPR images, the display rates of both the medial calcaneal nerve and the subcalcaneal nerve were 100%, and the starting point of the subcalcaneal nerve was always at the distal end of the starting point of the medial calcaneal nerve. In 55% of cases, there were more than two medial calcaneal nerve innervations. CONCLUSION: The 3D-FIESTA-C MPR can display the morphological features and positions of the tibial nerve and its branches and the bifurcation point's projection position can be marked on the body surface. This method not only benefited the imaging diagnosis of the tibial nerve and branch-related lesions in the ankle canal, but it also provided a good imaging basis to plan a clinical operation of the ankle canal and avoid surgical injury.

The determination of safe zones for arthroscopic portal placement into the posterior knee by mapping the courses of neurovascular structures in relation to bony landmarks.

PURPOSE: Minimally invasive surgery in the posterior knee is high risk for iatrogenic injury to popliteal neurovascular neurovasculature structures. This study aimed to use reliable landmarks to define safe zones for arthroscopic portal placement into the posterior knee. METHODS: Distances were measured between bony landmarks and neurovascular structures within the popliteal fossa using 45 formalin-embalmed cadavers: small saphenous vein (SSV), medial (MCSN) and lateral (LCSN) cutaneous sural nerves, tibial nerve (TN), common fibular nerve (CFN), popliteal vein (PV) and artery (PA). The structures were measured in relation to medial (MEF) and lateral (LEF) femoral epicondyle, medial (MCT) and lateral (LCT) tibial condyle and the midpoint between the landmarks. RESULTS: The mean distance (mm) between MEF and structures was, male and female, respectively: SSV 37.6 + 12.5, 37.9 + 8.2; MCSN 39.2 + 14, 38.8 + 10.1; TN 39.4 + 10.2, 38.0 + 8.1; PV 38.4 + 12.9, 32.8 + 5.6; PA 38.4 + 12.1, 34.6 + 4.9. At midpoint and MCT all structures medialized between 5 and 28%. The mean distance between LEF and structures was, male and female, respectively: CFN 13.4 + 8.2, 8.4 + 9.1; LCSN 24.9 + 7.3, 18.4 + 10.4. At midpoint and LCT the CFN lateralized by 37-42% and the LCSN medialized by 8-9%. CONCLUSIONS: Results suggest posteromedial portal placement can be safely established < 20 mm from the medial femoral epicondyle, tibial condyle or the midpoint between the two landmarks. Posterolateral portal placement is of higher risk, and entry point is 18 mm from the lateral femoral epicondyle, tibial condyle or the midpoint between the two landmarks in males and 12 mm in females. These landmarks will allow safe portal placement in 99% of cases.

Comparison of the histological structure of the tibial nerve and its terminal branches in the fresh and fresh-frozen cadavers.

BACKGROUND: The aim of this study was to compare the histological structure (cross-sectional area [CSA] and number of nerve fascicles) of the distal part of the tibial nerve (TN) and its terminal branches (medial plantar nerve [MPN], lateral plantar nerve [LPN]) in the fresh and fresh-frozen cadavers using computer assisted image analysis. MATERIALS AND METHODS: The TNs with terminal branches (MPN and LPN) were dissected from the fresh and fresh-frozen cadavers. Each nerve was harvested 5 mm proximally and respectively 5 mm distally from the TN bifurcation, marked, dehydrated, embedded in paraffin, sectioned at 2 µm slices and stained with haematoxylin and eosin. Then the specimens were photographed and analysed using Olympus cellSens software. RESULTS: The fresh cadavers' group comprised 60 feet (mean age 68.1 ± 15.2 years). The mean CSA and the number of nerve fascicles were respectively 15.25 ± 4.6 mm2, 30.35 ± 8.45 for the TN, 8.76 ± 1.93 mm2, 20.75 ± 7.04 for the MPN and 6.54 ± 2.02 mm2, 13.40 ± 5.22 for the LPN. The fresh-frozen cadavers' group comprised 21 feet (mean age 75.1 ± 9.0 years). The mean CSA and the number of nerve fascicles were respectively 13.71 ± 5.66 mm2, 28.57 ± 8.00 for the TN, 7.55 ± 3.25 mm2, 18.00 ± 6.72 for the MPN and 4.29 ± 1.93 mm2, 11.33 ± 1.93 for the LPN. Only LPNs showed statistical differences in the CSA and the number of nerve fascicles between examined groups (p = 0.000, p = 0.037, respectively). A positive correlation was found between donors age and tibial nerve CSA in the fresh cadavers group (r = 0.44, p = 0.000). A statistical difference was found between the MPN and LPN both in the CSA and the number of nerve fascicles (p < 0.001, p < 0.001, respectively). CONCLUSIONS: The CSA and the number of nerve fascicles of the tibial and medial plantar nerves were similar in the fresh and fresh-frozen cadavers whilst different in the LPN. The TN showed increasing CSA with the advanced age in the fresh cadavers. The MPN had larger CSA and more nerve fascicles than the LPN.

Ultrasound-guided topographic anatomy of the medial calcaneal branches of the tibial nerve.

BACKGROUND: The purpose of this study was to evaluate the topographic anatomy of the tibial nerve and its medial calcaneal branches in relation to the tip of the medial malleolus and to the posterior superior tip of the calcaneal tuberosity using the ultrasound examination and to verify its preoperative usefulness in surgical treatment. MATERIALS AND METHODS: Bilateral ultrasound examination was performed on 30 volunteers and the location of the tibial nerve bifurcation and medial calcaneal branches origin were measured. Medial calcaneal branches were analysed in reference to the amount and their respective nerves of origin. RESULTS: In 77% of cases, tibial nerve bifurcation occurred below the tip of the medial malleolus with the average distance of 5.9 mm and in 48% of cases above the posterior superior tip of the calcaneal tuberosity with the average distance of 2.7 mm. In 73% of cases medial calcaneal branches occurred as a single branch originating from the tibial nerve (60%). The average distance of the first, second and third medial calcaneal branch was accordingly 9.3 mm above, 9.5 mm below and 11.6 mm below the tip of the medial malleolus and 17.7 mm above, 1.6 mm below and 4 mm below the posterior superior tip of the calcaneal tuberosity. CONCLUSIONS: As the tibial nerve and its branches present a huge variability in the medial ankle area, in order to prevent the iatrogenic injuries, the preoperative or intraoperative ultrasound assessment (sonosurgery) of its localisation should be introduced into the clinic.

Computer-assisted measurements of the histological structure of the tibial nerve and its terminal branches.

BACKGROUND: The aim of this study was to analyse the histological structure (cross-sectional area [CSA] and number of nerve bundles) of the distal part of the tibial nerve and its terminal branches (medial plantar nerve, lateral plantar nerve) using computer-assisted image analysis. MATERIALS AND METHODS: The tibial nerve and its distal branches (medial and lateral plantar nerves) were dissected from the fresh cadavers. Each nerve was harvested 5 mm proximally and respectively 5 mm distally from the tibial nerve bifurcation, marked, dehydrated, embedded in paraffin, sectioned at 2 µm slices and stained with haematoxylin and eosin. Then photographed and analysed using Olympus cellSens software. RESULTS: The studied group comprised 28 female and 32 male feet (mean age 68.1 ± 15.2 years). The mean CSA and the number of nerve bundles were respectively 17.86 ± 4.57 mm2, 33.88 ± 6.31 for the tibial nerve, 9.58 ± 1.95 mm2, 23.41 ± 7.37 for the medial plantar nerve and 7.17 ± 2.36 mm2, 15.06 ± 5.81 for the lateral plantar nerve in males and 12.27 ± 2.45 mm2, 26.32 ± 8.87 for the tibial nerve, 7.81 ± 1.41 mm2, 17.71 ± 5.28 for the medial plantar nerve and 5.83 ± 1.25 mm2, 11.50 ± 3.72 for the lateral plantar nerve in females. Both CSA and number of nerve bundles of the tibial, medial plantar and lateral plantar nerves revealed no statistical differences when comparing foot side of the individual. The statistical difference was related to the gender, showing significantly bigger CSA and number of nerve bundles in males (CSA: p = 0.000, p = 0.000, p = 0.016; number of nerve bundles: p = 0.01, p = 0.003, p = 0.004, respectively). A positive correlation was found between the donor age and the tibial nerve CSA (r = 0.44, p = 0.000). A significant statistical difference was found between the medial and lateral plantar nerves both in CSA and number of nerve bundles (p < 0.001, p < 0.001, respectively). CONCLUSIONS: The CSA and the number of nerve bundles in the distal part of the tibial nerve and its branches are significantly larger in males with no differences between right and left foot of the individual. The tibial nerve shows increasing CSA with advanced age. The medial plantar nerve has larger CSA and more nerve bundles than the lateral plantar nerve.

Intramuscular innervation of plantaris muscle evaluated using a modified Sihler's staining protocol - Proposal for a new classification.

PURPOSE: The plantaris muscle is a morphologically variable structure with regard to both its origin and insertion, and the course of the tendon. We here determined the pattern of branching and distribution of intramuscular nerves of the plantaris muscle to determine its usability for autologous transplantation. No information exists on the innervation of the plantaris muscle using Sihler's staining technique, and hence its intramuscular nerves. The main purpose of the work is to determine the pattern of branching and distribution of the intramuscular nerves of the plantaris muscle. Is the plantaris muscle a good transplant candidate? MATERIALS AND METHODS: Eighty lower limbs from cadavers (40 left, 40 right, 40 male, 40 female, age range 41-94 years) were fixed in 10% formalin solution and examined macroscopically as well as morphometrically with regard to the innervation pattern of the respective plantaris muscle. Afterwards Sihler's staining was used in all 80 plantaris muscles to identify the exact distribution of the muscular branch originating from the main nerve trunk in the muscle belly. RESULTS: Two patterns of branching and nerve distribution could be intensified in the plantaris muscle: Type I, with a single pattern entire up to the muscle and then divided into superior and inferior intramuscular branches.; type II with a double innervation pattern (superior and inferior). The superior and inferior pattern were not connected to each other. CONCLUSION: The plantaris muscle reveals variability with two different innervation patterns. Type II is ideally suited for autologous transplantation. New classifications of innervation are desirable for individual muscles rather than a generalized approach.

Different patterns in age-related morphometric alteration of myelinated fibers and capillaries of the tibial nerve: a longitudinal study in normal rats.

Age-related regression of myelinated fibers in peripheral nerves of the lower limbs is strongly influenced by capillaries and results in balance dysfunction and falls. However, the temporal relationships between alteration patterns of myelinated fibers and capillaries have not yet been clarified. This study aimed to investigate age-related morphological and histological changes of both myelinated fibers and capillaries in peripheral nerves to clarify whether myelinated fibers or capillaries change earlier. Seven male Wistar rats each were randomly selected at 20 weeks (young group), 70 weeks (middle group), and 97 weeks (old group) for histological evaluations. The left and right tibial nerves were removed morphologically and histologically to examine myelinated fibers and capillaries. Axon diameter and myelin thickness were almost unaltered in the middle group compared with the young group but were significantly reduced in the old group when compared with the other two groups. However, the capillary diameter and number of microvascular branch points were substantially reduced in the middle group. The current study demonstrates that myelinated fibers of peripheral nerves show signs of regression in elderly rats, whereas capillaries start to reduce in middle-aged animals. In normal aging of the tibial nerve, capillaries may regress before myelinated fibers.

The injection site in the tarsal tunnel to minimize neurovascular injury for heel pain: an anatomical study.

INTRODUCTION: The aim of this study was to investigate the location and distribution patterns of neurovascular structures and determine the effective injection point in the tarsal tunnel for heel pain. METHODS: Fifteen adult non-embalmed cadavers with a mean age of 71.5 years were studied. The most inferior point of the medial malleolus of the tibia (MM) and the tuberosity of the calcaneus (TC) were identified before dissection. A line connecting the MM and TC was used as a reference line. The reference point was expressed in absolute distance along the reference line using the MM as the starting point. For measurements using MRI, the depth from the skin was measured to inferior at an interval of 1 cm from the MM. RESULTS: The posterior tibial artery, lateral plantar nerve, and medial plantar nerve were located from 29.0 to 37.3% of the reference line from the MM. The distribution frequencies of the medial calcaneal nerve on the reference line from the MM were 0%, 8.60%, 37.15%, 37.15%, and 17.10%, respectively. The mean depth of the neurovascular structures was 0.3 cm. DISCUSSION: This study recommended an effective injection site from 45.0 to 80.0% of the reference line.

Side-to-side supercharging nerve allograft enhances neurotrophic potential.

INTRODUCTION: Critical limitations of processed acellular nerve allograft (PNA) are linked to Schwann cell function. Side-to-side bridge grafting may enhance PNA neurotrophic potential. METHODS: Sprague-Dawley rats underwent tibial nerve transection and immediate repair with 20-mm PNA (n = 33) or isograft (ISO; n = 9) or 40-mm PNA (n = 33) or ISO (n = 9). Processed acellular nerve allograft groups received zero, one, or three side-to-side bridge grafts between the peroneal nerve and graft. Muscle weight, force generation, and nerve histomorphology were tested 20 weeks after repair. Selected animals underwent neuron back labeling with fluorescent dyes. RESULTS: Inner axon diameters, g-ratios, and axon counts were smaller in the distal vs proximal aspect of each graft (P < .05). Schwann cell counts were greater, with a lower proportion of senescent cells for groups with bridges (P < .05). Retrograde labeling demonstrated that 6.6% to 17.7% of reinnervating neurons were from the peroneal pool. DISCUSSION: Bridge grafting positively influenced muscle recovery and Schwann cell counts and senescence after long PNA nerve reconstruction.