Sonographic Evaluation of the Lateral Femoral Cutaneous Nerve: Single-Institution Experience and Pictorial Review

ABSTRACT

The location of the lateral femoral cutaneous nerve (LFCN) makes it susceptible to injury with trauma, external compression, and iatrogenic injury. The objectives of this study were to report the single-institution efficacy of LFCN visualization on ultrasound (US), define the clinical characteristics of patients with LFCN palsy, and describe sonographic appearances of LFCN abnormalities by pictorial review. A retrospective chart review of LFCN cases evaluated using US at a single institution was performed, documenting rate of visibility on US, mode of nerve injury, and US imaging findings. Nerve visibility rates on US were correlated with magnetic resonance imaging (MRI) when both modalities were used. Imaging findings were confirmed with clinical/surgical history and follow-up. Retrospective review found that 170 patients underwent US for LFCN evaluation in the last 10 years. Injury was associated with surgical intervention in 56% of cases, and perineural scarring was the most common pathology described using US. Lateral femoral cutaneous nerve was visible on US in 97% of cases; MRI visualized LFCN in 60%. Chart review showed US as an effective tool in evaluating LFCN pathology, with a higher visualization rate than MRI. Through pictorial review, the array of LFCN pathology sonographically detectable is demonstrated.

Surgical course of lateral femoral cutaneous nerve during anterior exposure of paediatric hips: an observational study

Anterior approach to the hip joint is commonly used for paediatric hip disorders. Lateral femoral cutaneous nerve (LFCN) is always exposed and dissected in this approach before deep dissection is carried out. The course of this nerve has been described in adults but there is a lack of literature regarding this in the paediatric age group. This study aimed to find the surgical anatomy of LFCN in children during the anterior approach to the hip. A total of 51 paediatric hip surgeries were done in 45 children for various hip disorders. The anterior exposure was done by the Somerville approach (Bikini incision). During surgical exposure, LFCN was exposed and its relationship to anterior superior iliac spine (ASIS), inguinal ligament and sartorius muscle was observed. In most of the cases (45/51) it was found as a single trunk below the inguinal ligament and medial to the ASIS. In one hip, multiple branches of the nerve were found just below the inguinal ligament. In four hip exposures, the nerve was not found in the surgical field and in one case nerve was accidentally cut during surgery as it was lying adherent to ASIS. There was no significant correlation between the observational parameters of the nerve with anthropometric variables. Nerve was mostly seen in area 5-25 mm medial to ASIS and 10-50 mm below the ASIS in 80% of our surgical exposures where the nerve was isolated. We observed that once LFCN is dissected, the injury during further surgical procedures can be prevented.

Cadaveric study investigating the femoral nerve-sparing volume for pericapsular nerve group (PENG) block

BACKGROUND

This cadaveric study investigated the maximum effective volume of dye in 90% of cases (MEV90) required to stain the iliac bone between the anterior inferior iliac spine (AIIS) and the iliopubic eminence (IPE) while sparing the femoral nerve during the performance of pericapsular nerve group (PENG) block.

METHODS

In cadaveric hemipelvis specimens, the ultrasound transducer was placed in a transverse orientation, medial and caudal to the anterior superior iliac spine in order to identify the AIIS, the IPE and the psoas tendon. Using an in-plane technique and a lateral-to-medial direction, the block needle was advanced until its tip contacted the iliac bone. The dye (0.1% methylene blue) was injected between the periosteum and psoas tendon. Successful femoral-sparing PENG block was defined as the non-staining of the femoral nerve on dissection. Volume assignment was carried out using a biased coin design, whereby the volume of dye administered to each cadaveric specimen depended on the response of the previous one. In case of failure (ie, stained femoral nerve), the next one received a lower volume (defined as the previous volume with a decrement of 2 mL). If the previous cadaveric specimen had a successful block (ie, non-stained femoral nerve), the next one was randomized to a higher volume (defined as the previous volume with an increment of 2 mL), with a probability of b=1/9, or the same volume, with a probability of 1-b=8/9.

RESULTS

A total of 32 cadavers (54 cadaveric hemipelvis specimens) were included in the study. Using isotonic regression and bootstrap CI, the MEV90 for femoral-sparing PENG block was estimated to be 13.2 mL (95% CI: 12.0 to 20.0). The probability of a successful response was estimated to be 0.93 (95% CI: 0.81 to 1.00).

CONCLUSION

For PENG block, the MEV90 of methylene blue required to spare the femoral nerve in a cadaveric model is 13.2 mL. Further studies are required to correlate this finding with the MEV90 of local anesthetic in live subjects.

Erectile Functional Restoration With Genital Branch of Genitofemoral Nerve to Pelvic Nerve Transfer After Spinal Root Transection in Rats

OBJECTIVE

To investigate the feasibility of erectile function restoration by the genitofemoral nerve to pelvic nerve transfer in rats.

METHODS

Thirty-six male rats were included in this study. Rats in the nerve transfer group (n = 12) were subjected to pelvic nerve, sacral roots, and L6 roots transection and then bilateral genitofemoral nerve to pelvic nerve transfer, rats in the nerve resection group (n = 12) were subjected to pelvic nerve, sacral roots, and L6 roots transection without nerve transfer, and rats in the control group (n = 12) served as controls. After reinnervation, intracavernous pressure (ICP) assessment was performed. Fluoro-Gold was injected into the corpus cavernosum. Immediately before euthanasia, transferred nerves were stimulated to test penile intracavernous pressure. The L6, S1, and L1-2 spinal cord segments were used for retrogradely labeled neurons. Regenerative nerve morphologic examination assessment was performed.

RESULTS

Genitofemoral nerve stimulation induced an increase in ICP in the nerve transfer group. The mean ICP in this group was (33.8 ± 9.4 mm Hg), which is higher than the mean value in the nerve resection group (3.9 ± 1.0 mm Hg) but lower than that in the control group (69.8 ± 12.2 mm Hg; P < .05). The formation of new neural pathways was confirmed by the appearance of Fluoro-Gold labeled neurons in the L-1 and L-2 spinal cord segments in the nerve transfer group. Regenerative nerve morphologic examination showed good axonal regeneration after genitofemoral nerve transfer.

CONCLUSION

Nerve regeneration can be obtained by genitofemoral nerve to pelvic nerve transfer, and erectile function can be restored.

The surgical anatomy of the lateral femoral cutaneous nerve in the inguinal region: a meta-analysis

Purpose

Several variations in the anatomy and injury of the lateral femoral cutaneous nerve (LFCN) have been studied since 1885. The aim of our study was to analyze the available data on the LFCN and find a true prevalence to help in the planning and execution of surgical procedures in the area of the pelvis, namely inguinal hernia repair.

Methods

A search of the major medical databases was performed for LFCN anatomy. The anatomical data were collected and analyzed.

Results

Twenty-four studies (n = 1,720) were included. The most common pattern of the LFCN exiting the pelvis was medial to the Sartorius as a single branch. When it exited in this pattern, it did so on average 1.90 cm medial to the anterior superior iliac spine (ASIS).

Conclusions

The LFCN and its variations are important to consider especially during inguinal hernia repair, abdominoplasty, and iliac bone grafting. We suggest maintaining a distance of 3 cm or more from the ASIS when operating to prevent injury to the LFCN.

Electronic supplementary material

The online version of this article (doi:10.1007/s10029-016-1493-7) contains supplementary material, which is available to authorized users.

Anatomic relationships of psoas muscle: clinical applications to psoas hitch ureteral reimplantation

OBJECTIVE

The objective of the study was to examine the anatomic relationship of the genitofemoral and femoral nerves to the psoas major muscle.

STUDY DESIGN

Dissections were performed in 17 unembalmed female cadavers. Point A was used as the approximate location for placement of psoas hitch sutures and as the reference point from which all measurements were taken. Measurements included the width of the psoas major muscle, psoas minor tendon, genitofemoral nerve branches, and femoral nerve. The relative location of the genitofemoral and femoral nerves to point A and the presence or absence of a psoas minor tendon were documented.

RESULTS

The psoas minor tendon was absent on at least 1 side in 11 specimens (64.7%). The median width of the psoas minor tendon was 7 mm (range, 3-11.5 mm). The median width and depth of the psoas major muscle was 21.5 mm (range, 10-35 mm) and 20.0 mm (range, 11.5-32 mm), respectively. The median width of the genitofemoral nerve was 2 mm (range, 1-4.5 mm) and that of the femoral nerve was 6.3 mm (range, 5-10.5 mm). Overall, 54 genitofemoral nerve branches were identified in 17 cadavers, 30 medial (55.5%), 22 lateral (40.7%), and 2 directly overlying point A (3.7%).

CONCLUSION

The exact location for the placement of the psoas hitch sutures will vary, depending on the location of the ureteral injury and the anatomy of the psoas muscle and surrounding structures. A thorough understanding of this regional anatomy should optimize the placement of psoas hitch sutures during ureteral reimplantation procedures and help avoid nerve and vessel injury.

The course of the distal saphenous nerve: a cadaveric investigation and clinical implications

INTRODUCTION

Injury to the saphenous nerve at the ankle has been described as a complication resulting from incision and dissection over the distal tibia and medial malleolus. However, the exact course and location of the distal saphenous nerve is not well described in the literature. The purpose of this study was to determine the distal limit of the saphenous nerve and its anatomic relationship to commonly identified orthopaedic landmarks and surgical incisions.

METHODS

Sixteen cadaveric ankles were examined at the level of the distal tibia medial malleolus. An incision was made along the medial aspect of the lower extremity from the knee to the hallux to follow the course and branches of the saphenous nerve under direct visualization. We recorded the shortest distance from the most distal visualized portion of the saphenous nerve to the tip of the medial malleolus, to the antero-medial arthroscopic portal site, and to the tibialis anterior tendon.

RESULTS

The saphenous nerve runs posterior to the greater saphenous vein in the leg and divides into an anterior and posterior branch approximately 3 cm proximal to the tip of the medial malleolus. These branches terminate in the integument proximal to the tip of the medial malleolus, while the vein continues into the foot. The anterior branch ends at the anterior aspect of the medial malleolus near the posterior edge of the greater saphenous vein. The posterior branch ends near the posterior aspect of the medial malleolus. The average distance from the distal-most visualized aspect of the saphenous nerve to the tip of the medial malleolus measured 8mm +/-; 5mm; from the nerve to the medial arthroscopic portal measured 14mm +/-2mm; and from the nerve to the tibialis anterior measured 16mm +/-3mm. In only one case (of 16) was there an identifiable branch of the saphenous nerve extending to the foot and in this specimen it extended to the first metatarsophalangeal joint. The first metatarsophalangeal joint was innervated by the superficial peroneal nerve in all cases. Small variations were also noted.

DISCUSSION AND CONCLUSIONS

This study highlights the proximity of the distal saphenous nerve to common landmarks in orthopaedic surgery. This has important clinical implications in ankle arthroscopy, tarsal tunnel syndrome, fixation of distal tibia medial malleolar fractures, and other procedures centered about the medial malleolus. While the distal course of the saphenous nerve is generally predictable, variations exist and thus the orthopaedic surgeon must operate cautiously to prevent iatrogenic injury. To avoid saphenous nerve injury, incisions should stay distal to the tip of the medial malleolus. The medial arthroscopic portal should be more than one centimeter from the anterior aspect of the medial malleolus which will also avoid the greater saphenous vein. Incision over the anterior tibialis tendon should stay within one centimeter of the medial edge of the tendon.

Iatrogenic femoral neuropathy: two cases and literature update

Iatrogenic femoral neuropathy is an uncommon surgical or obstetric complication that may be underreported. It results from compression, stretch, ischemia, or direct trauma of the nerve during hip arthroplasty, self-retaining retractor use in pelvicoabdominal surgery, lithotomy positioning for anesthesia or labor, and other more rare causes. Decreasing incidence of this complication after abdominal and gynecologic surgery but increase in its absolute numbers after hip arthroplasty has emerged over the last decade. We describe two illustrative cases related respectively to lithotomy positioning and self-retaining retractor use. The variability in clinical presentation of iatrogenic femoral nerve lesions, some new insights in their diverse pathophysiology, and in the diagnostic and treatment options are discussed with an update from the literature.

Femoral nerve blockade

Femoral nerve blockade is the most widely performed lower limb block. Methods of femoral nerve blockade are briefly reviewed with particular reference to ultrasound guidance.

The anatomical variation of the lateral femoral cutaneous nerve in relation to the anterior superior iliac spine and the iliac crest

The location of lateral femoral cutaneous nerve (LFCN) in relation to the anterior superior iliac spine (ASIS) and the iliac crest was investigated in 96 embalmed cadaveric specimens. Fifty-six nerves (58.3%) passed medial to the ASIS. Twenty-two nerves (22.9%) passed at the ASIS. Eighteen nerves (18.8%) passed lateral to the ASIS. The LFCN is usually located at 2.1 +/- 0.8 to 3.9 +/- 1.0 cm below the crest in the range of 2-5 cm lateral to the ASIS, respectively. When the anterior iliac crest bone graft harvesting is planned, the anatomical variation in this area should be concerned to reduce the risk of LFCN injury.

Infantile hip arthroscopy: the relationship between neurovascular anatomy and the portal pathway

OBJECTIVE

In the past, studies of hip arthroscopy portal path relate with extra-articular structures were done in adults. This study was investigated in the infantile group.

MATERIAL AND METHOD

10 hips of fresh infantile cadavers. K-wire diameter 2.4 mm. are representing scope pathway. Three portals (anterior, anterolateral and posterolateral) in supine position without traction were chose to used in this study.

RESULTS

One cadaver was female and four were male. The mean age and weight when death occurred was 74 days and the mean weight was 3584.4 gm. At the anterior portal, the most lateral branch of LFCN was frequently injured. The average distant of femoral nerve to the K-wire was 11.2 (7-14) mm. Transverse branch of lateral femoral circumflex artery had an average distant 8.5(6-14) mm and the terminal branch could be identified in four hip and average distance was 1 mm. At the anterolateral portal two, greater trochanter were injured by K-wire. In the posterolateral portal the average distant from K-wire to sciatic nerve was 13.2 mm.

CONCLUSION

From this pilot study, the distance of major neurovascular structure as related to hip scope path is nearly a centimeter on average.

High or low current threshold for nerve stimulation for regional anaesthesia

BACKGROUND

The purpose of this study was to determine whether the application of high stimulation current thresholds (SCT) leads to a distant needle to nerve proximity (NNP) compared with low SCT during nerve localization for regional anaesthesia in pigs.

METHODS

A minimal motor response to the stimulation of femoral or brachial plexus nerves in 16 anaesthetized pigs was triggered either by a minimal SCT of a low (0.01-0.3 mA) or a high (0.8-1.0 mA) current in a random order. After eliciting a motor response with a predetermined SCT, synthetic resin was injected via the needle. After postmortem dissection of the injection site, the localization of the resin deposition was determined verifying the final position of the needle tip. Depending on the proximity of resin deposition to the nerve epineurium, the needle tip placement was considered either as a close or a distant NNP.

RESULTS

A total of 235 punctures were performed. Ninety-one punctures were carried out with low SCT and 92 with a high SCT. Fifty-two punctures served as a control (1.8-2.0 mA). All injectates following both high or low SCT were considered 'close needle tip to nerve placement', whereas 27 of 52 injectates of the control group appeared distant to nerve epineurium.

CONCLUSION

Regardless of the applied SCT, i.e. high or low, all resin deposition was found adjacent to nerve epineurium. These findings suggest that high and low SCT result in equivalent needle tip localization in pigs.

Medial circumflex femoral artery with different origin and course: a case report and review of the literature

The femoral artery (FA) and its branches play important roles in the arterial supply of the lower extremity. If the femoral artery is occluded, the circulation of the extremity is maintained by certain anastomoses. Therefore, identification of variations of these arteries is critical from a clinical and surgical point of view. During routine anatomical dissections for student education at the Department of Anatomy of the School of Medicine at Ondokuz Mayls University, a variation of the medial circumflex femoral artery (MCFA) was observed and photographed in a male, formalin-fixed cadaver aged 55 years. In this case, MCFA branched off from the posterolateral aspect of the FA, 32 mm distal to the inguinal ligament. A frequency rate of 17-26% has been reported regarding this variation. However, MCFA emerging from the postero-lateral aspect of the FA and its course, as in this case, is not that frequent. Knowledge of anomalies in the emergence and course of the arteries that join the cruciate anastomosis and are important in the arterial supply of the head and neck of the femur appear to be a critical component that requires caution during surgical interventions towards this region.

The incidence and location of corona mortisA study on 75 cadavers

We dissected 150 fresh cadaver halves by ilioinguinal exposure, and counted all vessels more than 2 mm in diameter, connecting the obturator system to the external iliac system. The distance between the symphysis pubis and the anastomotic vessels was measured. We found vascular anastomoses between the obturator and external iliac systems in 91 of 150 sides (61%), and anastomotic veins in 78 of 150 exposures (52%). Arterial connections were seen in 29 of the exposures (19%). The mean distance between the anastomotic arteries and the symphysis pubis was 64 (45-90) mm, and 56 (37-80) mm for the communicating veins. There seemed to be no significant difference between genders in the incidence of corona mortis and the distance between communicating vessels and the symphysis pubis.

Sonographic assessment of the lateral femoral cutaneous nerve

PURPOSE

To evaluate the ability of high-frequency sonography to evaluate the lateral femoral cutaneous nerve (LFCN).

METHODS

A cadaveric study was performed on 5 cadavers to outline the normal course of the LFCN. Next, 37 LFCNs in 21 volunteers were evaluated via sonography with a 5-13-MHz linear-array transducer.

RESULTS

The LFCN was easily identified in our dissections. It always entered the thigh under the inguinal ligament and coursed superficially to the sartorius muscle. In 2/10 (20%) cases, anatomical variants were observed. Sonography revealed the LFCN in 26/37 (70%) cases. The relationships of the nerve with the deep circumflex iliac artery, the anterior superior iliac spine, and the sartorius were visualized. Neuromas were observed bilaterally in 1 volunteer.

CONCLUSION

The LFCN can be seen in the groin with the aid of sonography.

Anatomical and experimental studies of brachial plexus, sciatic, and femoral nerve-location using peripheral nerve stimulation in the dog

OBJECTIVE

To investigate the anatomy of the brachial plexus, sciatic, and femoral nerves for the use of a peripheral nerve-stimulator to perform nerve blocks in dogs.

STUDY DESIGN

Prospective experimental trial.

ANIMALS

Four canine cadavers and four healthy adult dogs weighing 23 +/- 2.5 kg.

METHODS

Phase I: in four canine cadavers, an anatomical study was conducted to evaluate accurate needle-insertion techniques. Phase II: the utility of these techniques, and the value of electrostimulation, were evaluated in four anesthetized dogs in lateral recumbency (medetomidine, 5 microg kg(-1)/ketamine 5 mg kg(-1)) using an electrical stimulator and shielded needles.

RESULTS

For the brachial plexus, the needle was inserted cranial to the acromion, medial to the subscapularis muscle, at an angle of approximately 20-30 degrees in relation to a plane vertical to the surface on which the animal was lying, oriented parallel to the long axis of the animal, in a ventro-caudal direction. For the sciatic nerve, the needle was inserted just cranial to the sacrotuberous ligament, through the gluteus superficialis muscle, at an angle of approximately 60 degrees in relation to the horizontal plane, in a ventro-cranial direction, and up to the level of the ischium. For the femoral nerve, the needle was inserted perpendicular to the skin, just cranial to the femoral artery, and directed a little caudally. Using a peripheral nerve-stimulator, all nerves were located, and muscle contractions were elicited at a current of 0.2-0.4 mA. No complications were observed during the procedures.

CONCLUSION

Electrostimulation of peripheral nerves is useful in locating the branches of the brachial plexus as well as the sciatic and femoral nerves in dogs.

CLINICAL RELEVANCE

Peripheral nerve stimulation increases the reliability of a nerve block when compared with blind needle-insertion.

Innervation of vastus lateralis muscle

The lateral surgical approach to the proximal femur potentially damages the nerve supply to the vastus lateralis (VL) muscle. This study describes the detailed anatomy of the nerve supply to the VL muscle based on dissection of ten cadaveric lower limbs. In all specimens, a single nerve trunk arose from the femoral nerve, which is most subsequently divided into two main divisions. These divisions gave two branches each. These branches coursed from anteriorly and proximally to posteriorly and distally within the muscle. When the muscle was reflected anteriorly from its attachment to the linea aspera, there was no damage to its innervation. Splitting of the VL in the midlateral line of the femur, however, resulted in denervation of the posterior half of the muscle. Precise knowledge of the nerve supply to the VL will help avoid iatrogenic denervation of the muscle in surgical procedures at the proximal femur through the lateral approach.

Nerve-identifying inguinal hernia repair: a surgical anatomical study

BACKGROUND

Pain syndromes of somatic and neuropathic origin are considered to be the main causes of chronic pain after open inguinal hernia repair. Nerve-identification during open hernia repair is suggested to be associated with less postoperative chronic pain. The aim of this study was to define clinically relevant surgical anatomical zones facilitating efficient identification of the three inguinal nerves during open herniorrhaphy.

METHOD

Through dissection of 18 inguinal areas of embalmed and unembalmed human cadavers, identification zones were developed for the inguinal nerves (in particular for the genital branch of the genitofemoral nerve).

RESULTS

The iliohypogastric nerve was identifiable running approximately horizontally and ventrally to the internal oblique muscle perforating the external oblique aponeurosis at a mean of 3.8 cm (range 2.5-5.5 cm) cranially from the external ring. When present, the ilioinguinal nerve was identifiable running ventrally and parallel to the spermatic cord, dorsally from the aponeurosis of the external oblique muscle. Identification of the genital branch of the genitofemoral nerve was more comprehensive. The course of the genital branch is laterocaudal at the level of the internal inguinal ring.

CONCLUSION

Based on the newly defined identification zones, peroperative identification of all inguinal nerves is possible. Further research is warranted to assess clinical feasibility of these zones and to evaluate the influence of (facultative) division, preservation or omittance of the identification of inguinal nerves on the incidence of chronic pain.

Anatomic variations in the lateral femoral cutaneous nerve with respect to pediatric hip surgery

Variations were documented in the course of the lateral femoral cutaneous nerve (LFCN) in the upper thigh relative to anatomic landmarks in 22 adult cadavers using the Smith-Petersen incision for the anterior approach to the hip. Distances from the anterior superior iliac spine (ASIS) to the point of nerve entry into the thigh were normalized as percentages of the distance from the ASIS to the pubic tubercle (PT) to relate the data to small children. In all cases, the LFCN passed deep to the inguinal ligament, entering the thigh a mean of 2.6 cm (SD, 1.9 cm) medial from the ASIS (19%+/-14% of the ASIS-PT distance), with distances ranging from 0.3 to 6.5 cm (2.6%-46.4%). With the data extrapolated to children, the LFCN may commonly be found medial to the ASIS about one fifth the distance from the ASIS to the PT. In 32% of cases, the LFCN ran directly inferiorly, but in 68% it coursed inferolaterally and then turned to run inferiorly close to the distal part of the incision. Expressed proportionally rather than only as mean measurements, these percentages provide a better estimate of the location of the LFCN in relation to patient size and thus are useful when operating in this region.

Free Inferior Gluteal Flap Harvest with Sparing of the Posterior Femoral Cutaneous Nerve

The free inferior gluteal flap is a major secondary choice of autologous tissue for breast reconstruction if the TRAM flap is not an option. Loss of posterior thigh and popliteal sensibility is a frequent sequela of harvesting the free inferior gluteal musculocutaneous flap and the inferior gluteal artery perforator (I-GAP) flap. The posterior femoral cutaneous nerve of the thigh lies directly on the deep surface of the gluteus maximus muscle, having a very close anatomic relationship with the inferior gluteal artery. The purpose of this study was to gain a better understanding of the anatomy of the posterior femoral cutaneous nerve (PFCN), its branches, and their relationship with the inferior gluteal artery (IGA). Eighteen fresh human pelvic halves were dissected for examination during harvesting of the inferior gluteal myocutaneous free flap, to determine if a nerve-sparing approach was possible and how this information might impact on I-GAP flap harvest. Seventeen of 18 pelvic halves had at least some of the PFCN branches intact after isolation of the IGA pedicle and flap elevation. Three of 18 of the pelvic halves had the entire PFCN and its branches intact after flap elevation. One of 18 pelvic halves required complete transection of the PFCN and its branches in order to isolate the IGA pedicle. In 94.5 percent of the pelvic halve dissections, it was possible to maintain at least a portion of the PFCN intact after isolation of the inferior gluteal artery pedicle while harvesting the free inferior gluteal myocutaneous flap. These findings support a nerve-sparing approach to inferior gluteal myocutaneous flap elevation to minimize the sequela of posterior thigh anesthesia. These data also emphasize the intimate relationship of the PFCN and the gluteal artery and the real possibility of injury to the PFCN during I-GAP harvest.

The Femoral Nerve and Its Relationship to the Lateral Circumflex Femoral Artery

Small branches of the femoral artery in the femoral triangle are not palpable and could increase the risk of intravascular injection during femoral nerve (FN) block. I evaluated the position of the lateral circumflex femoral artery (LCFA), a lateral branch of the femoral artery, in relationship to accepted landmarks for FN blockade, including the inguinal ligament, inguinal crease, and FA. Forty cadaver lower extremities were dissected. In 50% of specimens, the LCFA, as it crossed the FN, was within 1 cm of the inguinal crease, the recommended level for needle insertion for FN blockade. The mean depth of this artery at the inguinal crease was 1.7 cm, whereas the mean depth of the FN was 1.1 cm at this level. In most specimens, the LCFA coursed between the branches of the FN, although it sometimes lay deep to all of the branches. Knowledge of this anatomy may allow for safer FN blockade.

Lateral femoral cutaneous nerve and iliac crest bone grafts—anatomical and clinical considerations

This study investigates the topographical relationship of the lateral femoral cutaneous nerve (LFCN) to the anterior iliac crest and its clinical relevance in the context of bone graft harvesting. In the anatomical part of the study, LFCN was dissected and its course investigated in 34 human formalin-embalmed cadavers. In the clinical part, data of patients who underwent an iliac crest bone grafting procedure were collected and analysed. The obtained results were then compared with the results of other investigators published in the medical literature. From 34 nerves, the lateral branch of 1 LFCN (2.9%) crossed the anterosuperior iliac spine (ASIS) prominence at a distance less than 5mm superolaterally from the most anterior point of the spine. All other nerves ran below the inguinal ligament with an average distance of 14.6mm in the inferomedial direction from the spine. In 4 out of 298 patients (1.3%) who underwent harvesting of monocortical bone grafts from the inner table of the ilium, sensory disturbances in the dermatome of LFCN were observed. After a maximum period of 12 months all sensory disturbances resolved so that no case of permanent sensory impairment was recorded. The relatively low incidences of iatrogenic LFCN damage can be attributed to a standardized surgical concept which employs a lateral incision and layer by layer dissection to the periosteum/iliacal fascia level in order to identify the nerves potentially crossing the iliac crest above the ASIS.

Topographical relationship between the human lateral circumflex femral artery and saphenous nerve

This study was performed to investigate causes of various types of topographical relationship between the lateral circumflex femoral artery (L) and the saphenous nerve (S). Femoral artery (F), deep femoral artery (P), L and S of 186 legs of 93 Japanese adult cadavers were submitted to anatomy. Further, the levels of origin of L in thigh were measured. L were classified into nine types by the origins of L and topographical relationship between L and S. The incidence of various types of L is different among researchers. Our findings proved that these differences were caused by the differences in evaluations of twig from ascending branch (AB) or descending branch (DB) of L. In cases of L originating from F, incidence of L positioned in front of S is significantly higher than L originating from P (p < 0.01). In cases of L originating from F, L positioned in front of S originates from F at the significantly more proximal level compared to L positioned posterior to S (p < 0.001). Furthermore, also in cases of L originating from P, L positioned in front of S originates from P at the significantly more proximal level compared to L positioned posterior to S (p < 0.001). It is supposed that the topographical relationship between L and S changes depending on the artery where L originates and the level of origin of L.

The Extended Approach to the Vascular Pedicle of the Anterolateral Thigh Perforator Flap: Anatomical and Clinical Study

BACKGROUND

The anterolateral thigh perforator flap is a well-described and versatile flap that has specific advantages. However, the variable anatomy makes flap elevation challenging. Furthermore, the dissection of the proximal part of the pedicle that runs underneath the rectus femoris muscle demands continuous pull by an assistant and is inconvenient and tiring for the surgeon. A technique that facilitates dissection of the proximal pedicle part is suggested. It is useful in both pedicled and free flap transfer, when maximum pedicle length is crucial.

METHODS

Five anterolateral thigh perforator flaps were dissected using the extended technique. Four were transferred as free flaps and one as an island pedicled flap. In addition, anatomical cadaver studies were performed bilaterally in five fresh cadavers to further clarify the relevant anatomy.

RESULTS

All flaps survived well. One patient suffered from donor-site infection caused by inadequate drainage. Conservative treatment with daily dressing changes resulted in satisfactory healing. Two patients suffered from hypesthesia of part of the lateral thigh area. No patient experienced any difficulty in daily activities and none suffered from knee extension lag.

CONCLUSIONS

An extended approach for dissection of the anterolateral thigh perforator flap is described that is useful in both pedicled and free flap transfers. Cautious tunnel creation is a prerequisite for avoidance of complications.

The psoas quartus muscle

We report an unusual finding in an adult male cadaver. During the routine dissection of the posterior abdominal wall as part of an anatomy course at our institution, an anomalous muscle was noted. This muscle originated from the transverse process of the left L3 vertebrae and the medial aspect of the quadratus lumborum. We believe this muscle to represent a variety of the psoas quartus that, to our knowledge, has only been described once before in the extant medical literature. The presence of a psoas quartus muscle may contribute to femoral nerve compression. The clinician may wish to consider this rare muscular anomaly in patients with symptoms of femoral nerve compression in which no other clear etiology is found. Furthermore, clinicians who image the posterior abdominal wall should be aware of this potential anomaly when interpreting the anatomy of this region.

RETRACTED: A New Rule for Femoral Nerve Blocks

BACKGROUND AND OBJECTIVES

Acupuncture points are described by use of a proportional system that is based on the width of the thumb at the level of the distal interphalangeal joint, defined as 1 CUN. Our study tested first the correlation between the CUN and weight and height in 500 Americans and second the hypothesis that the CUN system is superior to the conventional landmarks to localize the femoral nerve 1 or 2 cm lateral to the artery in a prospective, double-blinded, randomized study.

METHODS

Sixty-two patients were randomized to receive a femoral nerve block by a needle entry point either 1 CUN lateral, 1 cm lateral, or 2 cm lateral to the femoral artery at the level of the inguinal crease. The time from needle entry to injection of local anesthetic was measured by an investigator blind to the technique, who also counted the frequency of needle repositioning, graded the ease of the block and its success, and registered complications.

RESULTS

Good correlation occurred between weight and CUN (r = 0.79) and height and CUN (r = 0.83), which indicates that the CUN of a normal person (predefined as 175 cm tall and 70 kg weight) is 18.7 +/- 1 mm. In the CUN group, the femoral block was achieved significantly faster (P < .01) with fewer attempts (P < .003). The success rate was the same and complications did not differ significantly between the groups.

CONCLUSION

A needle insertion point 1 CUN lateral to the midpoint of the palpated femoral artery at the level of the inguinal crease makes femoral nerve blocks faster and easier compared with conventional landmark 1 cm to 2 cm lateral to the artery.

Lateral femoral cutaneous nerve: an anatomic study

The purpose of our study was to determine the location of the lateral femoral cutaneous nerve and its branches at the inguinal ligament and proximal thigh. We think that further defining the location of the nerve and its branches based on certain measurements from known anatomic landmarks would enable us to determine a danger zone that could aid in preventing iatrogenic injury to the lateral femoral cutaneous nerve. The anatomic course of the lateral femoral cutaneous nerve was studied in 29 cadaver specimens and distances from various landmarks were recorded. In addition, the branching pattern of the nerves was recorded. We observed variability in the course and branching patterns of the lateral femoral cutaneous nerve. The lateral femoral cutaneous nerve was found to potentially be at risk as far as 7.3 cm medial to the anterior superior iliac spine along the inguinal ligament and as much as 11.3 cm distal on the sartorius muscle from the anterior superior iliac spine. As many as five branches of the lateral femoral cutaneous nerve were found and in 27.6% of cases the lateral femoral cutaneous nerve branched before traversing the inguinal ligament. We used this information to describe a danger zone, which could be used as a guide to help prevent unnecessary injury during certain procedures.

Motor points for neuromuscular blockade of the adductor muscle group

We sought to identify the motor nerve points for the adductor muscle group, relate them to specific surface anatomy markings, and define the points in terms of percentage distances along an anatomic reference line. We dissected four muscles in each of 20 legs from 15 skeletally mature, formalin-preserved cadavers. Multiple motor branches occurred in 21 of the 80 muscles dissected, but in only four limbs were they observed for more than one muscle in the group. Motor points (defined as the entry point of the motor branch into the muscle) were identified for each muscle along a reference line from the symphysis pubis to the medial joint line at the distal extent of the medial femoral condyle. The mean motor points and 95% confidence limits were as follows: adductor longus, 31% +/- 1.1%; adductor brevis, 22% +/- 1.8%; adductor magnus, 38% +/- 2.5%; and gracilis, 44% +/- 3.1%. Identification of these motor points facilitates accurate placement of neuromuscular blocking agents, such as botulinum toxin, and may lead to increased clinical efficacy of the block with a reduction in local or systemic side effects.

The Innervated Anterolateral Thigh Flap: Anatomical Study and Clinical Implications

During the past 20 years, the neural anatomy of many flaps has been investigated, although no extensive studies have been reported yet on the anterolateral thigh flap. The goal of this study was to describe the sensory territories of the nerves supplying the anterolateral thigh flap with dissections on fresh cadavers and with local anesthetic injections in living subjects. The sensate anterolateral thigh flap is typically described as innervated by the lateral cutaneous femoral nerve. Two other well-known nerves, the superior perforator nerve and the median perforator nerve, which enter the flap at its medial border, might have a role in anterolateral thigh flap innervation. Twenty-nine anterolateral thigh flaps were elevated in 15 cadavers, and the lateral cutaneous femoral nerve, the superior perforator nerve, and median perforator nerve were dissected. In the injection study, the lateral cutaneous femoral nerve, superior perforator nerve, and median perforator nerve in 16 thighs of eight subjects were sequentially blocked. The resulting sensory deficit from each injection was mapped on the skin and superimposed on the marked anterolateral thigh flap territory. The study shows that the sensate anterolateral thigh flap is basically innervated by all three nerves. The lateral cutaneous femoral nerve was present in 29 of 29 thighs, whereas the superior perforator nerve was present in 25 of 29 and the median perforator nerve in 24 of 29 thighs. Furthermore, in the proximal half of the flap, the lateral cutaneous femoral nerve lies deep, whereas the superior perforator nerve and median perforator nerve lie more superficially. Whereas the lateral cutaneous femoral nerve innervates the entire flap, the superior perforator nerve innervates 25 percent of the flap and the median perforator nerve innervates 60 percent of the flap. Clinically, a small anterolateral thigh flap (7 x 5 cm) can be raised sparing the lateral cutaneous femoral nerve and using only the selective areas innervated by the superior perforator and median perforator nerves. Alternatively, a large anterolateral thigh flap can be raised with this multiple innervation. This can be helpful if one wants to harvest the flap under local anesthesia. Sensate bilobed flaps can be harvested when dual innervated flaps are required.

Easily identifiable bony landmarks as an aid in targeted regional ankle blockade

Regional anesthesia around the ankle joint is well suited to a large number of surgical procedures of the foot. Previous studies have alluded to the variable nerve distribution of the foot, which may result in incomplete blocks. The aim of the study was to determine the position of the nerves in relation to the ankle joint to easily identifiable bony and prominent soft tissue landmarks to aid more accurate targeting of these nerves. A number of 94 ankles (47 left; 47 right) were dissected to expose the tibial, sural, deep fibular (peroneal), superficial fibular (peroneal), and saphenous nerves. The distance of the nerves relative to easy to find bony landmarks was measured. A distance (alpha) was measured from the middle of the tibial nerve to the most medial aspect of the medial malleolus. Measurement beta was considered from the inferior tip of the lateral malleolus to the anterior border of the sural nerve on a horizontal plane. Measurement delta was taken from the medial border of the deep fibular (peroneal) nerve to the most anterior aspect of the medial malleolus. epsilon was measured from the middle of the superficial fibular (peroneal) nerve to the most anterior aspect of the medial malleolus on a horizontal plane. The saphenous nerve was measured (gamma) from its medial border to the most anterior aspect of the medial malleolus on a horizontal plane. Factors such as sex, length, and ankle side were also analyzed concerning their influence on the position of the nerves. This study suggests that a greater degree of certainty may possibly be attained when palpable and easy to find bony landmarks are used to determine the position of the nerves around the ankle and ensure a simple to perform, predictable, and selectively targeted block.

A clinical case and anatomical study of the innervation supply of the vastus medialis muscle

The innervation supply to the vastus medialis (VM) muscle, a component of quadriceps femoris (QF), is provided by a branch of the femoral nerve (FN) running along the muscle. The course of the nerve from lumbar roots to the muscle has been described by many researchers. It is known to ride along the femoral vein, artery and saphenous nerve and enter the adductor canal (Hunter's canal), and then to divide into branches that supply vastus medialis and the knee joint. Femoral mononeuropathy is uncommon, and is usually due to compression in the spinal level. Hematoma in the psoas and iliacus muscles, drug abuse, lithotomy position and limb lengthening are the other associated reasons for a mononeuropathy of the femoral nerve. Isolated vastus lateralis (VL) atrophies have been reported by a few authors, suggesting that compression of the nerve and direct violation of the nerve with injections might be the reason for mononeuropathy. Isolated VM atrophy has not been previously reported. The purpose of the study was to identify the anatomical structures around the FN branch which innervates the VM muscle.

Neurovascular anatomy of the rectus femoris flap in the rabbit

The rectus femoris muscle in the rabbit represents a reliable flap for experimental work in many aspects of microsurgery. The operative exposure of the flap is often tricky for those unfamiliar with the anatomy, as is isolation of its neurovascular pedicle. Experience with 59 consecutive rectus femoris flaps demonstrated five separate patterns of arteral and venous pedicles. The nervous anatomy was found to be constant. Once recognized, these vessel patterns can be used to facilitate pedicle dissection, thus minimizing intraoperative mistakes which may endanger the viability of the flap.

A safe area and angle for harvesting autogenous tendons for anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) reconstruction with autogenous semitendinosus and gracilis tendons has become a common surgical procedure. Lower leg paresthesia following injury to the infrapatellar nerve during harvesting of the tendons has been well documented. Few authors have described the position of the infrapatellar nerve on a flexed knee, which is the position used during ACL reconstruction. The purpose of this study was to determine a safe area and angle where an incision could be made for harvesting of the semitendinosus and gracilis tendons, with the knee in flexion. Twenty right cadaver knees and 20 left knees were dissected. Landmarks on the knee were identified, from where the distances to the nerves (infrapatellar and saphenous) were measured with a vernier caliper. A safe area on the right knee was determined to be on the tibial tuberosity plane between 3.7 and 5.5 cm with a safe angle of incision of 51.6 degrees. A safe area on the left knee was determined to be on the tibial tuberosity plane between 3.6 and 4.9 cm with a safe angle of incision of 52.5 degrees. The results may assist orthopedic surgeons performing ACL reconstruction with semitendinosus and gracilis tendons to avoid cutaneous nerve damage and, therefore, patient discomfort.

Origin and course of nerves immunoreactive for calcitonin gene-related peptide surrounding the femoral artery in rat

Appreciation of anatomic relationships between perivascular nerve fibers and blood vessels is essential in reconstructive surgery. We examined the origin and neural connections of perivascular nerve fibers containing calcitonin gene-related peptide surrounding the femoral artery that regulate vascular tone. We used immunohistochemistry, denervation, and retrograde labeling methods. Peptide-immunoreactive fibers surrounding the femoral artery formed a complex network, with numerous small fibers extending from nerve fiber bundles located in the perivascular connective tissue. In middle and distal arterial segments, these fibers originated from the femoral nerve, the artery's main accompanying nerve. More proximally, fibers arose from the genitofemoral nerve and sympathetic nerves. Nerve branches terminating in various arterial segments had origins corresponding to those of somatic sensory nerve fibers, although pathways innervating the femoral artery took different courses.

Motor branch of the rectus femoris: anatomic location for selective motor branch block in stiff-legged gait

OBJECTIVE

To determine the ideal target point for selective motor branch block of the rectus femoris to treat stiff-legged gait.

DESIGN

Descriptive study.

SETTING

Anatomic institute of a university school of medicine in Korea.

CADAVERS

Twenty-two preserved adult cadavers.

INTERVENTION

The anterior thigh of the cadaver was dissected below the inguinal ligament. The motor branches of the 4 heads of the quadriceps were identified and traced from just below the inguinal ligament to the motor points.

MAIN OUTCOME MEASURES

The point T, where the motor branch of the rectus femoris is divided into smaller subbranches, was identified. Its location in relation to the surface anatomic landmarks was determined on the basis of the 2 anatomic lines that connect the anterior superior iliac spine to the medial femoral condyle, and the issuing spot of the femoral nerve below the inguinal ligament to the middle of the superior pole of the patellar.

RESULTS

The motor branch of the rectus femoris was divided into 2 subbranches at point T just before it reached the muscle. It nearly touched the medial margin of the rectus femoris at a proximal one-fourth to one-fifth point on 2 anatomic lines. The superior subbranch penetrated the muscle fascia at the posterior surface of the proximal one third of the muscle, whereas the inferior subbranch penetrated the muscle fascia at the medial border of the muscle.

CONCLUSION

The point T is the most suitable target point to selectively block the motor branch of the rectus femoris without affecting the other 3 motor branches of the femoral nerve in the treatment of stiff-legged gait.

Anatomical bases for minimizing sensory disturbance after arthroscopically-assisted anterior cruciate ligament reconstruction using medial hamstring tendons

The aim of this study was to improve surgical techniques for arthroscopically-assisted anterior cruciate ligament (ACL) reconstruction with minimal sensory disturbance in the infrapatellar and anterior lower leg regions. Thirteen patients with sensory disturbance were examined neurologically, and 51 lower limbs of 26 adult cadavers were examined anatomically to investigate the nerve branches supplying the regions. The region of sensory disturbance was supplied by branches of the medial femoral cutaneous nerve and the saphenous nerve, and the nerves showed a complementary distribution area. After detailed investigation of the positional relationships between the nerve branches and the skin incisions of the operative procedure, it was found that at least one branch of both nerves ran across the longitudinal skin incision (80%) for tendon harvest in the above-mentioned reconstruction. The complicated anatomic variations of the nerve branches preclude their absolute avoidance in any surgical incision, and a completely safe zone could not be found in the present study. However, an oblique incision for the tendon harvest rather than the typical longitudinal incision should be considered to minimize the sensory disturbance.

An anatomic study of the lumbar plexus with respect to retroperitoneal endoscopic surgery

STUDY DESIGN

The distribution of the lumbar plexus was analyzed using cadavers.

OBJECTIVE

To clarify the safety zone to prevent nerve injuries with respect to retroperitoneal endoscopic surgery.

SUMMARY OF BACKGROUND DATA

Surgical approaches to the retroperitoneal space vary among surgeons. Recently, retroperitoneal endoscopic surgery has been applied to various spinal disorders. When the psoas major muscle is separated during retroperitoneal endoscopic surgery, there is a potential risk of injury to the lumbar plexus or nerve roots. However, there is sparse knowledge regarding the relationship between the greater psoas muscle and the lumbar plexus.

METHODS

A total of 30 cadavers were analyzed. Six lumbar spines of the cadavers were cut in parallel with the lumbar disc space. Each axial section was photographed and captured into a computer. The distribution of the lumbar plexus was analyzed using computer images. The positions where the genitofemoral nerve emerged on the abdominal surface of the psoas major muscle were analyzed using 24 cadavers.

RESULTS

L2/3 and above, all parts of the lumbar plexus, and nerve roots were located from the dorsal fourth of the vertebral body and dorsally. The genitofemoral nerve descends obliquely forward through the psoas major muscle, emerging on the abdominal surface between the cranial third of the L3 vertebra and the caudal third of the L4 vertebra. The safety zone of the psoas major muscle to prevent nerve injuries, excluding the genitofemoral nerve, is at L4/L5 and above.

CONCLUSIONS

The safety zone, excluding the genitofemoral nerve, is at L4-L5 and above.

Applied anatomy of the genital branch of the genitofemoral nerve in open inguinal herniorrhaphy

OBJECTIVE

To record the anatomical variations and clinical importance of the genital branch of the genitofemoral nerve in the inguinal canal.

DESIGN

Neuropathology study.

SETTING

General hospital, Taiwan.

SUBJECTS

58 cadavers.

INTERVENTIONS

116 dissections findings of the genitofemoral nerve in the inguinal canal.

MAIN OUTCOME MEASURES

Anatomical variations.

RESULTS

All the genital branches passed through the ventral aspect of the internal ring. Almost all these branches entered the ring and continued within the spermatic cord between the fibres of the cremaster and the internal spermatic fascia. In 59% the nerve was related to the inferior fibres and in 38% it was in relation to the lateral or medial fibres. In only 3% did the genital branch run outside the spermatic cord.

CONCLUSION

To avoid damage to the genital branch of the genitofemoral nerve, suturing should be done over the dorsal aspect of the internal ring. The cremaster should be incised longitudinal rather than transversely and the genital branch of the genitofemoral nerve should be identified before repair of the posterior wall.

An anatomical and electrophysiological study of the genitofemoral nerve and some of its targets in the male rat

Anatomical descriptions of the genitofemoral nerve (GFn) innervating the lower pelvic area are contradictory. Here we re-examine its origin and innervation by its various branches of principal target organs in the male rat. Using gross dissection, electrophysiological techniques and retrograde tracing of motoneurones with horseradish peroxidase, we confirm that the GFn originates from lumbar spinal nerves 1 and 2, and that at the level of the common iliac artery it divides into a lateral femoral and a medial genital branch. In contrast to previous studies, we report that the genital and not the femoral branch innervates the abdominal-inguinal skin, and not only the genital but also the femoral branch innervates the cremaster muscle (Cm) surrounding the testes. Motoneurones innervating the Cm proper are located in the ventral nucleus of L1 and L2, and those innervating the muscular transition region of the rostral Cm are located in the ventral nucleus in L1 and the ventrolateral nucleus in L2. The GFn may contribute to male reproductive performance by transmitting cutaneous information during copulation and, via contraction of the Cm to promote ejaculation, the protective displacement of the testes into the abdominal cavity during fighting and as a sperm-protecting thermoregulatory measure.

[Distribution of the lateral cutaneous nerve of the thigh in the area of intramuscular injection]

The technique of intramuscular injection (IM) into the antero-lateral region of the thigh is widely used. Nevertheless, despite this area being indicated as the second best location for this practice, the technique is still observed to be very painful for both adult and child patients.

OBJECTIVE

To study the localization, distribution and course of the lateral cutaneous nerve of the thigh, and its topographic relationship with the area recommended for the practice of intramuscular injection, relating these characteristics to the pain resulting from such procedures.

METHOD

By means of exposing the antero-lateral region by classical dissection, the lateral cutaneous nerve of the thigh was identified and isolated in 20 fixed adult male cadavers, giving emphasis to the viewing of its nerve rami across the iliotibial tract.

RESULTS

In 100% of the cases, the lateral cutaneous nerve emerged medially in relation to the upper anterior iliac spine. After this, it issued three wide-caliber rami in 70% of the specimens and only two in the remaining 30%. In the upper third and in the upper portion of the middle third of the thigh, a network of numerous small nerve rami was observed, enveloped in a variable quantity of adipose tissue. However, in the lower portion of the middle third of the thigh and in the lower third, no significant nerve rami were seen.

CONCLUSION

Based on our data, we recommend whenever possible that the distal half of the region displayed by the classical technique be utilized as the location of choice for the practice of intramuscular injection into the antero-lateral region of the thigh. This is because this region is less innervated by the lateral cutaneous nerve of the thigh, which will cause less pain in this area during such procedures, thereby affording greater comfort to the patient.

[Femoral neuropathy after transversal suspubic laparotomies. Etiopathological explanation on the basis of an anatomical study]

OBJECTIVES

Based on a case of transient troncular femoral neuropathy after the surgical treatment of a genital prolapse in a 46-year-old woman, a study was designed to better understand the mechanism of this postoperative complication.

METHODS

The consequences of different varieties of transversal laparotomies were investigated in human cadavers.

RESULTS

On the basis of the data from the anatomical evaluation, the most probable etiopathogenic explanation for the complication we observed is the compression of the femoral nerve, inside the psoas muscle, by the retractor lower edge.

CONCLUSION

In the reported case, the outcome was simple with full sensory and motor recovery in the lower limb. The different mechanisms potentially involved in this kind of postoperative femoral neuropathies are reviewed and discussed.

Regional nerve blocks. Part 6--Femoral nerve blocks

This is the sixth in our series of regional nerve blocks. Femoral nerve blocks by a lateral approach, have the potential to block the lumbar plexus if sufficient volume is used.