Variations in sural nerve formation and course in fetuses.

To investigate variations regarding the formation and course of the sural nerve (SN). We dissected 60 formalin-fixed Brazilian fetuses (n = 120 lower limbs) aged from the 16th to 34th weeks of gestational age. Three incisions were made in the leg to expose the SN, and the gastrocnemius muscle was retracted to investigate the SN course. Statistical analyses regarding laterality and sex were performed using the Chi-square test. Eight SN formation patterns were classified after analysis. Type 4 (in which the SN is formed by the union of the MSCN with the LSCN) was the most common SN formation pattern. Although there was no statistical association between the formation patterns and the lower limb laterality (p = 0.9725), there was as to sex (p = 0.03973), indicating an association between anatomical variation and sex. The site of branch joining was in the distal leg most time (53.75%). In all lower limbs, the SN or its branches crossed from the medial aspect of the leg to the lateral margin of the calcaneal tendon (CT). Most often, the SN is formed by joining the MSCN and the LSCN in the distal leg. The SN or its branches ran close to the saphenous vein, crossed the CT from medial to lateral, and distributed around the lateral malleolus.

Anatomical patterns of the sural nerve: a meta-analysis with clinical and surgical considerations.

BACKGROUND: The sural nerve (SN) supplies the posterolateral aspect of the leg and the lateral aspects of the ankle and foot and descends through the gastrocnemius muscle along the lower third of leg. Because in-depth knowledge about SN anatomy is essential for clinical and surgical approaches, our study aims to review SN anatomical patterns. METHODS: We searched the PubMed, Lilacs, Web of Science, and SpringerLink databases to find relevant articles for meta-analysis. We assessed the quality of the studies using the Anatomical Quality Assessment tool. We used proportion meta-analysis to analyze the SN morphological variables and simple mean meta-analysis to analyze the SN morphometric variables (nerve length and distance to anatomical landmarks). RESULTS: Thirty-six studies comprised this meta-analysis. Overall, Type 2A (63.68% [95% CI 42.36-82.64]), Type 1A (51.17% [95% CI 33.16-69.04]) and Type 1B (32.19% [95% CI 17.83-48.38]) were the most common SN formation patterns. The lower third of leg (42.40% [95% CI 32.24-52.86]) and middle third of leg (40.00% [95% CI 25.21-53.48]) were the most common SN formation sites. The pooled SN length from nerve formation to the lateral malleolus was 144.54 mm (95% CI 123.23-169.53) in adults, whereas the SN length was 25.10 mm (95% CI 23.20-27.16) in fetuses in the second trimester of gestation and 34.88 mm (95% CI 32.86-37.02) in fetuses in the third trimester of gestation. CONCLUSIONS: The most prevalent SN formation pattern was the union of the medial sural cutaneous nerve with the lateral sural cutaneous nerve. We found differences regarding geographical subgroup and subject age. The most common SN formation sites were the lower and middle thirds of the leg.

Anatomy of the Sural Nerve in the Posterolateral Approach to the Ankle: A Cadaveric Study.

Sural nerve injury may occur during the posterolateral approach to the ankle during fracture fixation. We aimed to map its location in a posterolateral approach in cadaveric specimens. A posterolateral approach was used in 28 cadaver legs with the incision made halfway between the medial border of the fibula and the lateral border of Achilles tendon, extending proximally from the tip of the lateral malleolus. The sural nerve was identified and the distance from the distal tip of the incision to where it crossed the incision proximally was measured. The mean distance was 3.4 ± 1.2 (range 0.5-7.0) cm. In 22 cases (78.5%), the distance from the lowest part of the incision to the inferior part of the nerve was between 2.7 and 4.5 cm. The nerve did not cross the incision in 2 cases. We have demonstrated that the sural nerve crossed the posterolateral incision between 2.7 and 4.5 cm proximal to the tip of the fibula in the majority of cases. However, there remains individual anatomical variation, and we would recommend that care should be taken to look for the nerve closer to the Achilles tendon proximally and nearer the fibula distally. We hope that this information can help surgeons plan their approach and minimize iatrogenic injury to the sural nerve.

Ultrasound evaluation of a new surface reference line to describe sural nerve location and safe zones to consider in posterior leg approaches.

PURPOSE: Several authors have described methods to predict the sural nerve pathway with non-proportional numerical distances, but none have proposed a person-proportional, reproducible method with anatomical references. The aim of this research is to describe ultrasonographically the distance and crossing zone between a surface reference line and the position of the sural nerve. METHODS: Descriptive cross-sectional study, performed between January and April 2022 in patients requiring foot surgery who met inclusion criteria. The sural nerve course in the posterior leg was located and marked using ultrasound. Landmarks were drawn with a straight line from the medial femoral condyle to the tip of the fibula. Four equal zones were established in the leg by subdividing the distal half of the line. This way, areas based on simple anatomical proportions for each patient were studied. The distance between the marking and the ultrasound nerve position was measured in these 4 zones, creating intersection points and safety areas. Location and distances from the sural nerve to the proposed landmarks were assessed. RESULTS: One-hundred and four lower limbs, 52 left and 52 right, assessed in 52 patients were included. The shortest median distance of the nerve passage was 2.9 mm from Point 2. The sural nerve intersection was 60/104 (57.7%) in Zone B, 21/104 (20.1%) in Zone C and 19/104 (18.3%) in Zone A. Safety zones were established. Average 80.5% of coincidence in sural nerve localization was found in the distal half of the leg, in relation to the surface reference line when comparing both legs of each patient. CONCLUSIONS: This study proposes a simple, reproducible, non-invasive and, for the first time, person-proportional method, that describes the distance and location of the main areas of intersection of the sural nerve with points and zones (risk and safe zones) determined by a line guided by superficial anatomical landmarks. Its application when surgeons plan and perform posterior leg approaches will help to avoid iatrogenic nerve injuries. LEVEL OF EVIDENCE: IV.

Locating the danger zone to avoid injury to the sural nerve during Achilles calcaneal tendon repair. A systematic review of cadaveric studies with clinical implications.

INTRODUCTION: Although iatrogenic injuries to the sural nerve (SN) are commonly encountered in calcaneal (Achilles) tendon (CaT) repair surgeries, the relationship between both structures have anatomical variations. A quantitative evidence synthesis has not been yet conducted. Our systematic review aims to better define the safe zone where the SN crosses the lateral border of CaT. METHODS: Electronic databases were searched to locate relevant anatomical studies recording details regarding the distance at which SN crosses the CaT. The Checklist for Anatomical Reviews and Meta-Analyses (CARMA) was followed. The primary outcome was the mean distance from CaT insertion to SN crossing site, to locate a safe zone. The secondary outcome was the mean horizontal distance from the SN to the CaT lateral border. RESULTS: Seven studies met the inclusion criteria with a total of 204 cadaveric limbs. The danger zone was located 2 cm distal and proximal to the mean distance of the crossing point. The mean distance from CaT insertion to the SN crossing site was 9.91 ± 0.67 cm. The mean horizontal distance between SN and the CaT lateral border decreased from a mean of 19.8 ± 2.06 mm at the calcaneal tuberosity level to 3.6 ± 0.4 mm at 10 cm proximal to the tuberosity. DISCUSSION: This review demonstrated that 10 cm is the average distance from the CaT insertion onto the calcaneal tuberosity to the point of crossing of the SN. A safe zone would be 2 cm away proximally and distally from the crossing point. We recommend placing the proximal lateral sutures away from this region. This finding should help surgeons avoid SN injuries during open or percutaneous approaches for calcaneal tendon rupture.

Relationships of the superficial fibular nerve and sural nerve with respect to the lateral malleolus: implications for ankle surgeons.

PURPOSE: Superficial fibular nerve (SFN) and sural nerve are at risk during osteosynthesis of the lateral malleolus. The aim of this anatomical study was to describe the relationships of the superficial fibular and sural nerves with respect to the lateral malleolus. METHODS: Nine corpses (18 ankles) were dissected, using a direct lateral approach. Measurements were recorded between the fibula and the nerves, and the pattern variations of the SFN were recorded for both right and left side to assess intra-individual variability. RESULTS: Distance between the tip of the lateral malleolus and the piercing of fascia cruris was 111 ± 26 mm for type 1 pattern, and range was 46-161 mm all types included. 78% (14 SFN) were type 1 pattern, 17% (3 SFN) were type 2 pattern, and 5% (1 SFN) were type 3 pattern. 44% (4 specimen) had a type 1 pattern SFN on one ankle and another pattern on the other ankle. The sural nerve was always observed just posterior to the lateral malleolus. CONCLUSION: This study demonstrated a great inter-individual variability especially for the SFN, but also an intra-individual variability with frequent different patterns between right and left leg. It is important to know the anatomical variations of the SFN and sural nerve to decrease the risk of intra operative nerve injury during direct lateral approach of lateral malleolus.

Percutaneous Harvest of Calcaneal Bone Autograft: Quantification of Volume and Definition of Anatomical Safe Zone.

Bone grafting is commonly used in reconstructive foot and ankle surgery. The calcaneus provides an excellent site for graft harvest due to its rich vascularity and access to corticocancellous or strictly cancellous bone. The relatively thin soft tissue envelope makes dissection easy compared to more proximal autograft sites. In this investigation we quantified cancellous autograft volume from the calcaneus while simultaneously defining anatomical safe zones and identifying anatomical structures at risk. Nine matched-pair (18 total) fresh-frozen cadaveric below-knee limbs were utilized. All limbs were thawed at room temperature prior to the procedure. Calcaneal autograft was harvested following the senior author's (D.J.E.) technique. Bone graft was packed and quantified by podiatric medical students (B.R. and J.T.). An independent investigator (K.S.) meticulously dissected the lateral calcaneal soft tissue envelope to determine rates of neurovascular compromise. Anatomical safe zones were defined by measurements of the harvest site compared to vital anatomical structures. Cancellous autograft averaging 0.85 cc was obtained through an average cortical opening of 0.77 cm. The stab incision is approximately 2.2 cm anterior to the posterior aspect of the calcaneus and 1.6 cm superior to the inferior aspect of the calcaneus. This incision is an average 1.8 cm from the main branch of the sural nerve. No neurovascular damage was found. This study details percutaneous harvest of calcaneal autograft for use in forefoot or midfoot surgeries with an emphasis on feasibility of this additional procedure. The technique proposed is valuable based on simplicity, wide anatomic safe zone, and potential improvement of surgical outcomes.

Low to moderate risk of nerve damage during peroneus longus tendon autograft harvest.

PURPOSE: This study aims to evaluate the proximity of the tendon stripper to both the peroneal and sural nerves during peroneus longus tendon (PLT) autograft harvesting. METHODS: Ten fresh-frozen human cadaveric lower extremities were used to harvest a full-thickness PLT autograft using a standard closed blunt-ended tendon stripper. The distance to the sural nerve from the PLT (at 0, 1, 2 and 3 cm proximal to lateral malleolus (LM), and the distance to the peroneal nerve and its branches from the end of the tendon stripper were measured by two separate observers using ImageJ software. RESULTS: The average distance from the PLT to the sural nerve increased significantly from 0 to 2 cm proximal to LM. The average distance to the sural nerve at the LM was 4.9 ± 1.5 mm and increased to 10.8 ± 2.4 mm (2 cm proximal to LM). The average distance from the tendon stripper to the deep peroneal nerve was 52.9 ± 11.4 mm. The average distance to the PLT branch of peroneal nerve was 29.3 ± 4.2 mm. The superficial peroneal nerve, which coursed parallel and deep to the tendon stripper, was on average 5.2 ± 0.7 mm from the end of the stripper. No transection injuries of the nerves were observed in any of the ten legs after harvesting. CONCLUSION: This cadaver study found during a full-thickness PLT harvest, the distances between the tendon stripper and the nerves were greater than 5 mm with an initial incision at 2 cm proximal to LM which is recommended.

Anatomy of the sural nerve complex: Unaccounted anatomic variations and morphometric data.

BACKGROUND: The sural nerve (SN) is a cutaneous sensory nerve innervating the posterolateral leg. The SN is formed from a highly variable set of contributing nerves called the sural nerve complex (SNC). The SNC is made up of the lateral sural cutaneous nerve, medial sural cutaneous nerve, sural communicating branch, and SN. The SN is frequently cited as the most common donor nerve graft and is commonly injured in procedures of the lower extremity. Recent meta-analysis standardized six morphologies of the SNC and established a required reporting criterion for the group of nerves forming the SN. Due to the inconsistencies in previous literature, this study will group observed SNC's by one of these six SNC morphologies to assess and validate the meta-analysis grouping criteria. This study will also collect the same morphometric data previously outlined in order to grow the number of samples that are reported in a standardized fashion. METHODS: 100 formalin and 4 Theil preserved cadavers (n = 208) lower limbs were bilaterally dissected at Kansas City University and Creighton University School of Dentistry to observe the SNC in its entirety on the posterolateral leg. Anatomic data was captured utilizing the standardized morphologies types 1-6 with two sub-typing. Nerves that were found to be outside of this categorization were placed in an unassigned grouping. RESULTS: The most prevalent SNCs were type 1 at 41.35% (n = 86) and type 3 nerves at 34.62% (n = 72). Type 2 was found 8.65% (n = 18), type 4 and 5 were found each at 0.48% (n = 1). Type 6 was not observed. When comparing the present studies frequency of nerve types 1-6 to the meta-analysis a sub-grouping of "North American" cadaveric studies a X2 = .903 p = .030 was found. Two distinct and previously unassigned formations of the SNC were 10.58% (n = 20) and 3.85% (n = 8) of data. These two SNC are termed type 7 & 8, these represent two formations of SN that are outside of what was previously reported. 15.87% (n = 33) did not match visual descriptions based on nerve origin of a type 1 SNC but met written definitions. These were termed type 1A1 and type 1A2. The SNC was asymmetrical in 57.69% (n = 120). The pooled mean length of the SN was 32.97 ± 14.12 cm (31.05-34.88), mean diameter was 2.31 ± 0.83 mm (2.20-2.42, and the distance of the posterior border of the lateral malleolus to the SN was found to be 1.72 ± 0.70 cm (1.63-1.80). CONCLUSION: Anatomic variation in the SNC is highly variable, yet is consistent with previously observed literature. This study demonstrates two unaccounted formations of the SNC as well as two additional subcategories of SNC that were not included in the previous meta-analysis. These four variants warrant inclusion as standard formations of the SNC due to the high prevalence observed in this study as well as historical consistency observed in previous literature and case reports. These two SNC formations increase the risk of iatrogenic injury during surgical interventions of the lower extremity. Morphometric data describing the spatial relationship of this nerve complex on the posterolateral leg is consistent with previously reported data and aids in generating a large data set for future studies to characterize spatial properties of this nerve complex.

Free neurosensory flap based on the accompanying vessels of lateral sural cutaneous nerve: anatomic study and preliminary clinical applications.

BACKGROUND: The posterior aspect of the leg is an ideal donor site for flap surgery. In this study, the anatomy was investigated of the lateral sural cutaneous nerve (LSCN) and its accompanying artery, superficial lateral sural artery (SLSA), and a lateral sural neurocutaneous flap was designed. METHODS: Five fresh adult cadaver legs perfused with red latex were dissected to observe the course and relationship between LSCN and SLSA. The outer diameter of SLSA at its origin was measured. Then a lateral sural neurocutaneous flap was designed and used to repair soft tissue defects in six patients. RESULTS: The anatomic results showed that the SLSA gave rise to branches that followed the LSCN and ramified into terminals at the ramification of the nerve. It originated directly from the popliteal artery 4.2 ± 0.2 mm above the fibular head, where its outer diameter was 0.96 ± 0.23 mm. Several perforators penetrated from the crural fascia and anastomosed to the SLSA, creating a fine anastomotic network. The clinical results showed that the size of the flap ranged from 12 × 6 cm to 25 × 8 cm. All six flaps survived completely without complications. Follow-up ranged from 6 to 18 months with 11 months on average. The overall contour and sensory recovery of the flap were satisfied. CONCLUSION: A free innervated flap may be elevated safely based on the LSCN and its accompanying vessels. It provides an alternative in reconstruction of soft tissue defects where sensory recovery is important.

A calcaneal tunnel for CFL reconstruction should be directed to the posterior inferior medial edge of the calcaneal tuberosity.

PURPOSE: Anatomical reconstruction of the calcaneofibular ligament (CFL) is a common technique to treat chronic lateral ankle instability. A bone tunnel is used to fix the graft in the calcaneus. The purpose of this study is to provide some recommendations about tunnel entrance and tunnel direction based on anatomical landmarks. METHODS: The study consisted of two parts. The first part assessed the lateral tunnel entrance for location and safety. The second part addressed the tunnel direction and safety upon exiting the calcaneum on the medial side. In the first part, 29 specimens were used to locate the anatomical insertion of the CFL based on the intersection of two lines related to the fibular axis and specific landmarks on the lateral malleolus. In the second part, 22 specimens were dissected to determine the position of the neurovascular structures at risk during tunnel drilling. Therefore, a method based on four imaginary squares using external anatomical landmarks was developed. RESULTS: For the tunnel entrance on the lateral side, the mean distance to the centre of the CFL footprint was 2.8 ± 3.0 mm (0-10.4 mm). The mean distance between both observers was 4.2 ± 3.2 mm (0-10.3 mm). The mean distance to the sural nerve was 1.4 ± 2 mm (0-5.8 mm). The mean distance to the peroneal tendons was 7.3 ± 3.1 mm (1.2-12.4 mm). For the tunnel exit on the medial side, the two anterior squares always contained the neurovascular bundle. A safe zone without important neurovascular structures was found and corresponded to the two posterior squares. CONCLUSION: Lateral landmarks enabled to locate the CFL footprint. Precautions should be taken to protect the nearby sural nerve. A safe zone on the medial side could be determined to guide safe tunnel direction. A calcaneal tunnel should be directed to the posterior inferior medial edge of the calcaneal tuberosity.

Sural nerve harvest for infants: integrated with information based on anatomical dissections

Background/aim: The aim of the present study was to determine the course and possible variations of the sural nerve with all anatomical details in human fetal cadavers. Materials and methods: This study was performed on 60 fetal cadavers. Formation type and level of the sural nerve was detected. Results: According to trimesters, it was determined that the mean transverse and vertical distance between the lowest point of the LM and the SN varied between 1.1 and 2.9 mm and 1.54 and 3.58 mm, respectively. Type 2 was the most common seen type of sural nerve (35.83%). It was determined that the sural nerve was mostly formed at the middle third of the leg (42.5%). Conclusion: Sural nerve graft with the knowledge of the anatomical details may be used for peripheral nerve reconstruction is required in congenital lesions, such as facial paralysis, obstetric brachial paralysis, and posttraumatic lesions in infants and children.

Anatomic relationship of the sural nerve when performing Achilles tendon repair using the percutaneous Achilles repair system, a cadaveric study.

BACKGROUND: Minimally invasive techniques for Achilles tendon repair are increasing due to reports of similar rerupture rates using open and percutaneous techniques with fewer wound complications and quicker recovery with percutaneous methods. The goal of this study was to investigate quantitatively the relationship and risk of injury to the sural nerve during Achilles tendon repair when using the Percutaneous Achilles Repair System (PARS) (Arthrex®, Naples, FL), by recording the distance between the passed needles and the sural nerve as well identifying any direct violation of the nerve with needle passage or nerve entrapment within the suture after the jig was removed. The hypothesis of the study is that the PARS technique can be performed safely and without significant risk of injury to the sural nerve. METHODS: A total of five needles were placed through the PARS jig in each of 10 lower extremity cadaveric specimens using the proximal portion after simulation of a midsubstance Achilles tendon rupture. Careful dissection was performed to measure the distance of the sural nerve in relation to the passed needles. The sutures were then pulled out through the incision as the jig was removed from the proximal portion of the tendon and observation of the suture in relation to the tendon was documented. RESULTS: Of the 10 cadaveric specimens, none had violation of the sural nerve. Zero of the 50 (0%) needles directly punctured the sural nerve. In addition, upon retraction of the jig, all sutures were noted to reside within the tendon sheath with no entrapment of the sural nerve noted. CONCLUSION: This study demonstrated the variable course of the sural nerve and identifies the potential risk for sural nerve injury when using the PARS for Achilles tendon repair. However, this study provides additional evidence of safety from an anatomic standpoint that explains the outcomes demonstrated in the clinical trials. With this information the authors believe surgeons should feel comfortable they can replicate those outcomes while minimizing risk of sural nerve injury when the technique is used correctly.

The Reverse Sural Artery Flap: A Reliable and Versatile Flap for Wound Coverage of the Distal Lower Extremity and Hindfoot.

The reverse sural artery flap is a distally based fasciocutaneous or adipofascial flap used for wound coverage of the distal one-third of the lower extremity, ankle, and posterior heel. The flap harvest can be performed without sacrificing major arteries of the lower extremity. It can be elevated and mobilized with relative ease and a short operative time. It provides a good alternative to free tissue transfer in complex lower-extremity wounds with exposed bone, tendon, or hardware. The surgeon must be familiar with the management of venous congestion to improve the success of the flap.

The anatomy of the saphenous and sural nerves as a source of processed nerve allografts.

As an alternative to autologous nerve donors, acellular nerve allografts (ANAs) have been studied in many experiments. There have been numerous studies on processing ANAs and various studies on the clinical applications of ANA, but there have not been many studies on sources of ANAs. The purposes of the present study were to evaluate the course of the saphenous and sural nerves in human cadavers and help harvest auto- or allografts for clinical implications. Eighteen lower extremities of 16 fresh cadavers were dissected. For the saphenous nerve and sural nerve, the distances between each branch and the diameters at the midpoint between each branch were measured. In the saphenous nerve, the mean length between each branch ranged from 7.2 to 28.6 cm, and the midpoint diameter ranged from 1.4 to 3.2 mm. In the sural nerve, the mean length between each branch ranged from 17.4 to 21 cm, and the midpoint diameter ranged from 2.3 to 2.8 mm. The present study demonstrates the length of the saphenous and sural nerve without branches with diameters larger than 1 mm. With regard for the clinical implications of allografts, the harvest of a selective nerve length with a large enough diameter could be possible based on the data presented in the present study.

Intra-neural ganglion cyst of the lateral dorsal cutaneous nerve: an uncommon cause of lateral ankle pain.

INTRODUCTION: An intra-neural ganglion cyst of the lateral dorsal cutaneous branch of the sural nerve is rare, with only a few cases reported in the literature. MATERIALS AND METHODS: We carried out a retrospective investigation of patients with an intraneural ganglion cyst of the lateral dorsal cutaneous nerve. RESULTS: We present a case series of four patients with intra-neural ganglion cysts of the lateral dorsal cutaneous nerve, the distal continuation of the sural nerve at the lateral aspect of the foot. CONCLUSION: Intra-neural ganglion cysts of the lateral dorsal cutaneous nerve are rare. They represent a relatively uncommon source of lateral ankle pain, which can easily be diagnosed with ultrasound (US) and magnetic resonance imaging and managed effectively with US-guided aspiration or surgical excision.

Anatomical structures at risk in the arthroscopic Broström-Gould procedure: A cadaver study.

BACKGROUND: The Broström Gould procedure is the gold standard for repair of lateral ankle ligament injury and ankle instability. This procedure has demonstrated excellent short- and long-term outcomes in the orthopedic literature. Arthroscopic Broström Gould techniques have become increasingly popular among some foot and ankle orthopedic surgeons. Typically, this technique requires standard anteromedial and anterolateral portals along with an accessory lateral working portal. The exact location of this portal is variable within the available described surgical techniques. The objective of this cadaveric study is to establish a standard entry point for and to assess the safety of the accessory lateral portal with respect to nearby anatomical structures. METHODS: Ten fresh-frozen below-knee cadaver specimens were used. The location of the accessory lateral portal was created 1.5 cm anterior to the distal tip of the fibula. A small vertical incision was made at this point, followed by insertion of a Kirschner wire into the joint. The wire was then gently impacted into the fibula. Superficial dissection was subsequently carried out around the entry point to identify the peroneal tendons, superficial peroneal nerve branches, and sural nerve branches. Structures were marked with colored push pins, and distance was measured between the nearest edge of the Kirschner wire and each of the three anatomic structures listed. Any instances of structural contact or damage were documented. RESULTS: The average distance from the Kirschner wire to the peroneal tendon was 16.1 (±4.41) mm. The average distance from the wire to the superficial peroneal nerve and sural nerve was 13.11 (±6.79) mm and 12.33 (±4.08) mm, respectively. There were no instances of injury to any of the studied structures. However, there was a notable amount of variability in the proximity of structures in question for each cadaver. A branch of the superficial peroneal nerve was measured as close as 2 mm and as far as 24 mm in separate cadaver specimens. CONCLUSION: Arthroscopic Broström Gould procedures are a safe and effective method for lateral ankle ligamentous repair but are not without risk. Accessory lateral portal placement is relatively safe but should be meticulously executed to avoid damage to nearby anatomical structures.

Distribution patterns of the cutaneous nerves on the dorsum of the foot and their clinical significance.

The aim of this study was to clarify the distribution patterns of the cutaneous nerves on the dorsum of the foot. This study investigated 130 feet of 77 cadavers. The distribution patterns of the sural (SN) and deep fibular nerves (DFN) were classified into five and four types, respectively. In Type A, the SN was only distributed to the lateral side of the fifth toe. In Type B, the nerve was distributed to the medial side of the fourth toe and both sides of the fifth toe. In Type C, the nerve was mainly distributed to the lateral side of the fifth toe. In Type D, the nerve was distributed to the lateral side of the third toe and both sides of the fourth and fifth toes. In Type E, no SN was found. In Type α, the DFN was simultaneously distributed to the lateral side of the first toe and the medial side of the second toe. In Type ß, the nerve was distributed like in Type α and additionally to the medial side of the first toe. In Type γ, the nerve was distributed like in Type α and additionally to the lateral side of the second toe and the medial side of the third toe. In Type δ, no DFN was found. The results of this study will help physicians to reduce the incidence of iatrogenic nerve injury and improve the quality of diagnoses of relevant nerves in this body region. Clin. Anat. 33:592-597, 2020. © 2019 Wiley Periodicals, Inc.

The arthroscopic all-inside ankle lateral collateral ligament repair is a safe and reproducible technique.

PURPOSE: Neurovascular structures around the ankle are at risk of injury during arthroscopic all-inside lateral collateral ligament repair for the treatment of chronic ankle instability. This study aimed to evaluate the risk of damage to anatomical structures and reproducibility of the technique amongst surgeons with different levels of expertise in the arthroscopic all-inside ligament repair. METHODS: Twelve fresh-frozen ankle specimens were used for the study. Two foot and ankle surgeons with different level of experience in the technique performed the procedure on 6 specimens each. The repair was performed following a standardized procedure as originally described. Then, an experienced anatomist dissected all the specimens to evaluate the outcome of the ligament repair, any injuries to anatomical structures and the distance between arthroscopic portals and the superficial peroneal nerve (SPN) and sural nerve. RESULTS: Dissections revealed no injury to the nerves assessed. Mean distance from the anterolateral portal and the SPN was of 4.8 (range 0.0-10.4) mm. The mean distance from the accessory anterolateral portal to the SPN and sural nerve was of 14.2 (range 7.1-32.9) mm and 28.1 (range 2.8-39.6) mm, respectively. The difference between the 2 surgeons' groups was non-statistically significant for any measurement (mm). In all specimens both fascicles of the anterior talofibular ligament were reattached onto its original fibular footprint. The calcaneofibular ligament was not penetrated in any specimen. CONCLUSIONS: The all-inside arthroscopic lateral collateral ligament repair is a safe and reproducible technique. The clinical relevance of this study is that this technique provides a safe and anatomic reattachment of the anterior talofibular ligament, with minimal risk of injury to surrounding anatomical structures regardless of the level of experience with the technique.

Ipsilateral S2 nerve root transfer to pudendal nerve for restoration of external anal and urethral sphincter function: an anatomical study.

Patients suffer bilateral sacral plexus injuries experience severe problems with incontinence. We performed a cadaveric study to explore the anatomical feasibility of transferring ipsilateral S2 nerve root combined with a sural nerve graft to pudendal nerve for restoration of external anal and urethral sphincter function. The sacral nerve roots and pudendal nerve roots on the right side were exposed in 10 cadavers. The length from S2 nerve root origin to pudendal nerve at inferior border of piriformis was measured. The sural nerve was used as nerve graft. The diameters and nerve cross-sectional areas of S2 nerve root, pudendal nerve and sural nerve were measured and calculated, so as the number of myelinated axons of three nerves on each cadaver specimen. The length from S2 nerve root to pudendal nerve was 10.69 ± 1.67 cm. The cross-sectional areas of the three nerves were 8.57 ± 3.03 mm2 for S2, 7.02 ± 2.04 mm2 for pudendal nerve and 6.33 ± 1.61 mm2 for sural nerve. The pudendal nerve contained approximately the same number of axons (5708 ± 1143) as the sural nerve (5607 ± 1305), which was a bit less than that of the S2 nerve root (6005 ± 1479). The S2 nerve root in combination with a sural nerve graft is surgically feasible to transfer to the pudendal nerve for return of external urethral and anal sphincter function, and may be suitable for clinical application in patients suffering from incontinence following sacral plexus injuries.