An anatomic consideration of the femoral nerve during direct anterior hip approach: A cadaveric study.

PURPOSE: This study aimed to investigate the distance and correlation between the anatomy of the anterior side of the hip joint and the femoral nerve. METHODS: Using ten fresh-frozen cadavers with twenty hip joints. We dissected and marked the femoral nerve in the inguinal area. Employing the direct anterior approach, we identified and marked study points, including the superior and inferior points of the anterior rim of the acetabulum, » point, half point, and ¾ point along an imagined line connecting the formers, the inferomedial and mid aspect of the femoral neck, and the soft spot. Coronal plane measurements gauged the distance between these points and the femoral nerve. The collected data were analyzed to assess the distance and correlation. RESULTS: In the coronal plane, the median distance between the inferior point of the anterior rim of the acetabulum and the femoral nerve was 0 millimeters (interquartile range [IQR] 0-0). Likewise, the median distance between the mid aspect of the medial side of the femoral neck and the femoral nerve was 0 millimeters (IQR 0-0). Additionally, the mean distance between the soft spot and the femoral nerve was 1.18 cm (SD 0.63). CONCLUSION: Surgeons approaching the hip joint via the direct anterior approach should be cautious at the inferior point of the anterior rim of the acetabulum and the mid aspect of the femoral neck. The soft spot at the anterior rim of the acetabulum remains safe from direct injury when surgeons use the correct technique during anterior retractor insertion.

Optimal retractor insertion point for nerve safety during total hip arthroplasty: an anatomical study on the femoral and sciatic nerves in relation to hip motion.

BACKGROUND: Nerve injury is one of the most serious complications of total hip arthroplasty (THA). It is suspected to be a result from nerve compression or direct injury caused by an acetabular retractor. The anatomical relationship between the acetabular rim and the femoral and sciatic nerves, including hip motion, has not been investigated. This study aimed to identify the optimal position for retractor insertion during THA to prevent nerve damage. METHODS: A total of 28 hip joints from 14 freshly frozen cadavers were used. Using an anterolateral approach, each cadaver was immobilised in the lateral decubitus position and deployed to measure the distance between the nerves and the acetabular rim, while the hip joint was changed to the extension, neutral, and flexion positions. RESULTS: Three femoral nerves were closest to the anterior margin of the acetabulum at 90° and 120° of extension and farthest away at 30° of flexion. The sciatic nerve was closest to the posterior margin of the acetabulum at 90° and 120° of flexion and farthest away at 30° and 150° of extension compared with the other points. CONCLUSIONS: To prevent nerve damage during THA, we suggest that the retractor be inserted at the points where the nerves are the farthest away, such as at 30° and 150°. The femoral and sciatic nerves vary in their movements depending on the hip position. Therefore, the safe insertion of a retractor is recommended for hip flexion of the femoral nerve and extension of the sciatic nerve. Additionally, it is important to carefully insert the retractor along the acetabular margin without penetrating the joint capsule. Overall, this study provides valuable insights into the anatomical location and movement of the femoral and sciatic nerves in relation to hip motion and can help inform surgical techniques for safer THA.

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.

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.

Revisiting the surgical anatomy of the triangle of doom and the triangle of pain.

Better understanding of the surgical anatomy of the triangle of doom and the triangle of pain with fixed bony landmarks like the anterior superior iliac spine (ASIS) and the pubic symphysis (PS) can help in defining a safe location for trocar placement during laparoscopic surgeries and minimize neurovascular complications. Ten cadavers were dissected bilaterally to explore the surgical anatomy of both the triangles. ASIS and PS were evaluated in relation to the deep inguinal ring, external iliac artery, femoral nerve, and inferior epigastric artery. The deep inguinal ring was located at a depth of ~3 cm, about 4.9 ± 0.56 cm along the y-axis and 6.2 ± 0.94 cm along the x-axis, from the ASIS. The external iliac artery was located ~4.33 ± 0.6 cm along the y-axis and 7.29 ± 0.76 along the x-axis from the ASIS. The inferior epigastric artery was at ~4.31 ± 0.38 cm from the midline at the level of ASIS. This knowledge can help in the surface localization of both the triangles and prevent injury to the various neurovascular structures in relation to these triangles. In the current study, cranial to the ASIS lying at a distance of >5 cm from the midline was observed to be a safe zone for accessory trocar placement. The umbilical port has been observed to be safe for trocar placement. The mean angle between ductus deferens and testicular vessels was observed to be 43.5° ± 4.79°, which could help in determining their relative locations during various surgical procedures.

Anatomical Analysis of the Lateral Femoral Cutaneous Nerve and Its Passage beneath the Inguinal Ligament.

BACKGROUND: Meralgia paraesthetica is a mononeuropathy of the lateral femoral cutaneous nerve. According to the literature, the nerve travels beneath the inguinal ligament 1.3 to 5.1 cm medial to the anterior superior iliac spine. Compression at this site may cause pain and paresthesia. The aim of this study was to provide more accurate measurements to improve the diagnostic and surgical management of meralgia paraesthetica. METHODS: The lateral femoral cutaneous nerve was dissected bilaterally in 50 Thiel-embalmed human cadavers. Measurements were performed with a standard caliper at the superior and inferior margins of the inguinal ligament. The distance from the inner lamina of the anterior superior iliac spine to the medial margin of the lateral femoral cutaneous nerve was measured. Data were collected and statistical analysis was performed with R. RESULTS: Ninety-three lateral femoral cutaneous nerves of 50 cadavers were dissected. In 6 percent of cadavers, the lateral femoral cutaneous nerve could not be found. The mean distance from the inner lamina of the anterior superior iliac spine to the lateral femoral cutaneous nerve's medial border was 2.1 ± 1.3 cm (range, 0.2 to 6.4 cm; 95 percent CI, 1.8 to 2.4 cm) at the superior margin of the inguinal ligament and 1.9 ± 1.4 cm (range, 0.2 to 3.0 cm; 95 percent CI, 1.6 to 2.2 cm) at the inferior border of the inguinal ligament. CONCLUSION: This anatomical study shows that the majority of the lateral femoral cutaneous nerve passes beneath the inguinal ligament in a very narrow area of 0.6 cm.

Surgeon-performed pericapsular nerve group (PENG) block for total hip arthroplasty using the direct anterior approach: a cadaveric study.

BACKGROUND: During total hip arthroplasty (THA) using the direct anterior approach, orthopaedic surgeons can identify all anatomical landmarks required for pericapsular nerve group (PENG) blocks and carry out the latter under direct vision. This cadaveric study investigated the success of surgeon-performed PENG block. Success was defined as dye staining of the articular branches of the femoral and accessory obturator nerves. METHODS: 11 cadavers (18 hip specimens) were included in the current study. To simulate THA in live patients, an orthopaedic surgeon inserted trial prostheses using the direct anterior approach. Subsequently, a block needle was advanced until contact with the bone (between the anterior inferior iliac spine and iliopubic eminence). 20 mL of 0.1% methylene blue was injected. Cadavers were then dissected to document the presence and dye staining of the femoral, lateral femoral cutaneous, obturator and accessory obturator nerves as well as the articular branches of the femoral, obturator and accessory obturator nerves. RESULTS: Methylene blue stained the articular branches of the femoral nerve and the articular branches of the accessory obturator nerve (when present) in all hip specimens. Therefore, surgical PENG block achieved a 100% success rate. Dye stained the femoral and obturator nerve in one (5.6%) and two (11.1%) hip specimens, respectively. No dye staining was observed over the accessory obturator nerve in the pelvis nor the lateral femoral cutaneous nerve. CONCLUSION: Surgeon-performed PENG block during direct anterior THA reliably targets the articular branches of the femoral and accessory obturator nerves. Future trials are required to compare surgeon-performed PENG block with anaesthesiologist-performed, ultrasound-guided PENG block, and surgeon-performed periarticular local anaesthetic infiltration.

A guideline for femoral nerve block with the age-related formulas obtained from the distances between the femoral nerve and surface anatomical landmarks in fetal cadavers / Una guía para el bloqueo del nervio femoral con fórmulas relacionadas con la edad obtenidas a partir de las distancias entre el nervio femoral y los puntos de referencia anatómicos superficiales en cadáveres fetales

SUMMARY: The femoral nerve (FN) is used for nerve block in many surgeries and provides effective postoperative analgesics in the pediatric population. However, although there are sufficient anatomical maps and signs for femoral nerve blockades in adults, there is not enough information for the pediatric group. Therefore, in our study, we tried to determine an effective area for safe block blocking with the help of bone structures in order to perform effective blockade in younger age groups. The study was conducted on 60 lower limbs. The exit point of the FN was identified. The measurements were examined in two regards, namely the level of the FN and the relationship of the FN with the surrounding structures. For the right and left sides, all the parameters showed increases with age. A significant relationship was found between all the parameters of the fetal cadavers (p<0.01). It was determined that there was a strong correlation between all parameters related to FN and surrounding bone structures (p<0.01). Sex was not found to be significantly related to the other parameters (p<0.05 Among all the fetal cadavers, high-level division was observed in six limbs (10 %), mid-level division in 33 limbs (55 %), and lower-level division in 21 limbs (35 %). Gestational age-based regression equations from my study showed that the site of the blockage could be effectively performed with the aid of palpable bone structures from the outside without the need for technical assistance.

RESUMEN: El nervio femoral (NF) se utiliza para el bloqueo nervioso en muchas cirugías y proporciona analgesia posoperatoria eficaz en la población pediátrica. Sin embargo, aunque existen suficientes mapas anatómicos y signos de bloqueo del NF en los individuos adultos, no hay suficiente información para el grupo pediátrico. Se intentó determinar una área exacta para el bloqueo del NF junto con estructuras óseas para realizar un bloqueo efectivo. El estudio se realizó en 60 miembros inferiores. Se identificó el punto de salida del NF. Las mediciones se realizaron en dos puntos, nivel del NF y la relación de éste con las estructuras circundantes. Para los lados derecho e izquierdo, todos los parámetros mostraron incrementos con la edad. Se encontró una relación significativa entre todos los parámetros de los cadáveres fetales (p<0,01). Se determinó que existía una fuerte correlación entre todos los parámetros relacionados con el NF y las estructuras óseas circundantes (p <0,01). No se encontró que el sexo se relacionara significativamente con los otros parámetros (p<0,05 Entre todos los cadáveres fetales se observó un alto nivel de división en seis miembros (10 %), una división de nivel medio en 33 miembros (55 %) y división de nivel inferior en 21 miembros (35 %). Las ecuaciones de regresión basadas en la edad gestacional del estudio mostraron que el sitio de bloqueo se podría realizar eficazmente con la ayuda de estructuras óseas palpables desde el exterior sin necesidad de asistencia técnica.

A Crucial But Neglected Anatomical Factor Underneath Psoas Muscle and Its Clinical Value in Lateral Lumbar Interbody Fusion-The Cleft of Psoas Major (CPM).

OBJECTIVE: To describe the anatomical feature positioned beneath the psoas muscle at the lateral aspect of the lower lumbar, and to create a new location system to identify the risk factors of lateral lumbar interbody fusion. METHODS: Six cadavers were dissected and analyzed. The anatomy and neurovascular distribution beneath the psoas major from L3 to S1 was observed and recorded, with particular focus on the L4/5 disc and below. The psoas major surface was divided homogeneously into four parts, from the anterior border of psoas major to the transverse process. The cranial-to-caudal division was from the lower edge of the psoas muscle attachment on the L4 vertebrae to the upper part of the S1 vertebrae, and was divided into five segments. Then a grid system was used to create 20 grids on the psoas major surface, from the anterior border of the muscle to the transverse process and from L4 to superior S1 , which was used to determine the anatomical structures' distribution and relationship beneath the psoas major. RESULTS: A cleft was identified beneath the psoas major, from the level of L4/5 downwards. It was filled with loose connective tissue and neurovascular structures. We termed it the cleft of psoas major (CPM). The sympathetic trunk, ascending lumbar vein, iliolumbar vessels, obturator nerve, femoral nerve and occasionally the great vessels are contained within the CPM, although there is significant interpersonal variation. The grid system on the psoas major surface helped to identify the anatomical structures in CPM. There was a considerably lower frequency of occurrence of neurovascular structures in the grids of I/II at the L4/5 level where can be considered the "safe zones" for the lateral lumbar interbody fusion. In contrast, the distribution of neurovascular structures at the L5 S1 level is dense, where the operation risk is high. CONCLUSION: The CPM exists lateral to the vertebral surface from L4 and below. Although the occurrence and distribution of neurovascular structures within the CPM is complex and varies greatly, it can provide a potential cavity for visualization during lateral lumbar interbody fusion. Using psoas major as a reference, this novel grid system can be used to identify the risk factors in CPM and thus identify a safe entry point for surgery.

Split unilateral del nervio femoral a nivel del músculo psoas mayor: reporte de caso / Unilateral femoral nerve split at the psoas major muscle: case report

RESUMEN: El nervio femoral (NF) es el mayor o ramo del plexo lumbar. Normalmente se origina de las divisiones posteriores del segundo al cuarto ramo anterior del plexo lumbar (L2-L4). El músculo psoas mayor tiene su origen a nivel de las vértebras T12 a L5, se fusiona con el músculo ilíaco para luego insertarse en el trocánter menor del fémur. Normalmente, a nivel de la pelvis menor el NF se encuentra entre los músculos ilíaco y psoas mayor. En este trabajo presentamos un caso donde el músculo psoas mayor se relaciona con divisiones o split del NF, esta es una rara variación en la división y curso del NF con relación al músculo psoas mayor. Se observó que el NF se dividía en dos ramos por sobre el plano del ligamento inguinal después de su origen en el plexo lumbar. El NF del lado izquierdo se formó por las ramas ventrales de L2 a L4, a nivel de L5 el nervio es perforado por fascículos del músculo psoas mayor. La división inferior del NF pasaba profundamente a las fibras del músculo iliopsoas y la división superior pasaba superficialmente al músculo psoas mayor y profundo a la fascia ilíaca. Después de un trayecto de 60,21 mm ambas divisiones se unieron, después de atrapar fibras músculo iliopsoas justo inmediatamente proximal al ligamento inguinal para formar el tronco del NF. Si bien las causas embriológicas de las variaciones de los nervios periféricos se remontan a la quinta y sexta semana de vida intrauterina, la expresión clínica de disfunciones neuromusculares aparecerá varios decenios después. De modo que los médicos de las áreas de la traumatología y neurología deben estar al tanto de tales variantes anatómicas para entender mejor el dolor y los síndromes asociados a la compresión nerviosa y durante las maniobras quirúrgicas en esta región.

SUMMARY: AbstractThe femoral nerve (NF) is the major branch (or ramus) of the lumbar plexus. It normally originates from the posterior divisions of the second to fourth anterior branches of the lumbar plexus (L2-L4). The psoas major muscle originates at the level of the T12 to L5 vertebrae, fuses with the iliacus muscle and then inserts into the lesser trochanter of the femur. Normally, at the level of the lesser pelvis, the NF is found between the iliacus and psoas major muscles. In this paper we present a case where the psoas major muscle is related to divisions or splitting of the NF, this is a rare variation in the division and course of the NF in relation to the psoas major muscle. The NF was observed to divide into two branches above the plane of the inguinal ligament after its origin in the lumbar plexus. The NF on the left side was formed by ventral branches from L2 to L4, at the level of L5 the nerve is perforated by fascicles of the psoas major muscle. The lower division of the NF passed deep to the fibers of the iliopsoas muscle and the upper division passed superficial to the psoas major muscle and deep to the iliac fascia. After a path of 60.21 mm both divisions joined, after trapping iliopsoas muscle fibers just immediately proximal to the inguinal ligament to form the NF trunk. While the embryological causes of peripheral nerve variations date back to the fifth and sixth week of intrauterine life, the clinical expression of neuromuscular dysfunctions will appear several decades later. Thus, physicians in the areas of traumatology and neurology should be aware of such anatomical variants to better understand pain and syndromes associated with nerve compression and during surgical maneuvers in this region.

A systematic review and meta-analysis of the hip capsule innervation and its clinical implications.

Detailed understanding of the innervation of the hip capsule (HC) helps inform surgeons' and anaesthetists' clinical practice. Post-interventional pain following radiofrequency nerve ablation (RFA) and dislocation following total hip arthroplasty (THA) remain poorly understood, highlighting the need for more knowledge on the topic. This systematic review and meta-analysis focuses on gross anatomical studies investigating HC innervation. The main outcomes were defined as the prevalence, course, density and distribution of the nerves innervating the HC and changes according to demographic variables. HC innervation is highly variable; its primary nerve supply seems to be from the nerve to quadratus femoris and obturator nerve. Many articular branches originated from muscular branches of the lumbosacral plexus. It remains unclear whether demographic or anthropometric variables may help predict potential differences in HC innervation. Consequently, primary targets for RFA should be the anterior inferomedial aspect of the HC. For THA performed on non-risk patients, the posterior approach with capsular repair appears to be most appropriate with the lowest risk of articular nerve damage. Care should also be taken to avoid damaging vessels and muscles of the hip joint. Further investigation is required to form a coherent map of HC innervation, utilizing combined gross and histological investigation.

Topography and evidence of a separate "fascia plate" for the femoral nerve inside the iliopsoas - A dorsal approach.

The femoral nerve stretch test is an essential part of clinical neurological examinations. This test is performed alongside Magnetic Resonance Imaging (MRI) to determine if there is any evidence of nerve root irritation, usually as a consequence of disc prolapse. The test occasionally gives false positive results. Why such false positives can occur, is subject to continued research, however, no obvious reason has yet emerged. We hypothesize that connectives of the femoral nerve may explain such a phenomenon. To see these connectives, we approached the femoral nerve from dorsal in 12 cases. With the use of ink injection into the subparaneural compartment of the femoral nerve and dissections, a thin transparent structure can clearly be seen that is separate from the epineurium, perineurium, and a paraneural sheath. A continuation of the paraneural sheath produces a fascia plate approximately 1.5 cm in width and with a thickness of around 3 mm, which not only circumnavigates the nerve but projects into the surrounding tissues. Our qualitative observations show that not only does this femoral nerve fascia plate exists, but it also contains nerves and vessels. Furthermore, we show that the femoral nerve is connected to the myofascial complex of the iliopsoas, and in a separate fascia plate from the iliopsoas fascia. This plate is a hitherto neglected connective which extends as far as the spinal dura mater. Evidence from our plastinates and histological sections suggests that when tension is applied to the femoral nerve during the femoral nerve stretch test, tension is also applied to the femoral nerve fascia plate. The femoral nerve fascia plate could be a specific factor that contributes to pain resulting in a false positive femoral nerve stretch test.

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 posterior femoral cutaneous nerve contributes significantly to sensory innervation of the lower leg: an anatomical investigation.

BACKGROUND: Incomplete peripheral nerve blocks distal to the popliteal region are commonly considered a sciatic and femoral/saphenous nerve block failure. The existence of a much more distal innervation area of the posterior femoral cutaneous nerve (PFCN) as described has not been assumed yet. We therefore investigated the distal termination of the PFCN in the lower leg. METHODS: In 83 human lower extremities embalmed with Theil's method, the course of the PFCN was investigated from the sub-gluteal fold to the most distal macroscopically dissectible branch. The topographic connection to other landmarks, such as the small saphenous vein or small arteries, was investigated. RESULTS: Popliteal ending of the PFCN was found in 9.7% of cases. The PFCN terminated at the proximal or distal lower leg in 45.7% and 44.6% of cases, respectively. The PFCN had a close connection to the Achilles tendon in 13.2% of cases and was found distally to the medial malleolus in one case. The small saphenous vein was close to the PFCN in 90.3% of cases and can therefore be used as a landmark to identify the nerve. In 40.9% of cases, the PFCN was accompanied by a small descending branch of the inferior gluteal artery. In two cases, an innervation of the fibula or calcaneus periosteum was found. CONCLUSIONS: The PFCN has a much more distal termination in the lower leg than previously demonstrated. To ensure complete anaesthesia of the lower leg and foot, the PFCN must be included in combined peripheral nerve block procedures.

Anatomical course of the lateral femoral cutaneous nerve with special reference to the direct anterior approach to total hip arthroplasty.

Objectives: To document the anatomical variation of the lateral femoral cutaneous nerve (LFCN) at the proximal aspect of the thigh and to determine its susceptibility to injury during total hip arthroplasty via a direct anterior approach (DAA).Methods: We obtained 64 thighs from formalin-preserved cadavers of 45 Japanese individuals. LFCN was identified at the level of the inguinal ligament. All nerve branches of the LFCN were carefully traced distally in the subcutaneous tissue. The branching pattern and distribution at the proximal aspect of the thigh were described. A safe zone to avoid LFCN injury in DAA was estimated for the skin incision.Results: The branching pattern of LFCN was highly varied. There were 37% of the anterior type, characterized by a thicker anterior branch, which coursed along the medial border of the tensor fascia lata (TFL) muscle with thinner branches. There were 63% of the posterior type, characterized by posterior branches thicker than or equal to the anterior branch. In 27 of 64 thighs (42%), the LFCN crossed the skin incision along the midline of the TFL muscle.Conclusion: LFCN showed anatomical variation of anterior and posterior branches and 42% were in danger of injury during DAA.

Anterior acetabular retractors and the femoral neurovascular bundle in anterior total hip arthroplasty: a cadaveric study.

PURPOSE: The direct anterior approach for primary total hip arthroplasty (THA) has become increasingly popular in recent years. Nerve compression or traction with a retractor is a common cause of nerve injury in this approach. The purpose of this cadaveric study was to evaluate the anatomic relationship of the femoral neurovascular bundle to the anterior acetabular retractor during direct anterior approach THA. METHODS: Eleven fresh-frozen cadavers underwent a standard direct anterior THA, with placement of an anterior acetabular retractor in the usual fashion between the iliopsoas and acetabulum for visualization during acetabular preparation. Careful dissection of the femoral triangle was performed, and the distances from the anterior retractor tip to the femoral nerve, artery, and vein were recorded and analyzed as mean distance ± standard deviation. RESULTS: In all 11 cadavers, the retractor tip was medial to the femoral nerve. The mean distance from retractor tip to femoral artery and vein was 5.9 mm (SD = 5.5, range 0-20) and 12.6 mm (SD 0.7, range 0-35), respectively. CONCLUSIONS: Surgeons should be aware of the proximity of the neurovascular structures in relation to the anterior acetabular retractor in the direct anterior approach, taking care to avoid perforating the iliopsoas muscle during retractor insertion and limit excessive traction to prevent nerve injury.

Meralgia paresthetica: finding an effective cure.

Meralgia Paresthetica (MP) is one of the most common mononeuropathies of the lower limb. MP usually resolves on its own, even without treatment. However, many physicians are not aware of this diagnosis and may confuse patients with another nerve disease such as radiculopathies. Although no motor symptoms are associated with this condition, the sensory dysfunctions are potentially debilitating to patients. The variable course of the lateral femoral cutaneous nerve also complicates treatments. Thus, the author recommends the use of ultrasonography to help locate the nerve. Many treatments for MP are available, but they are supported only by moderate to low-quality evidence. Treatments range from conservative to interventions using nerve blocks and surgery. Without a clear superiority of any treatment, the author concludes that treatment should be done in a stepwise fashion, from the noninvasive to the more invasive treatment if symptoms persist.

Anatomical study of the infrapatellar branch of the saphenous nerve with applications to knee surgery / Estudio anatómico de la rama infrapatelar del nervio safeno con aplicaciones a la cirugía de rodilla

The infrapatellar branch of the saphenous nerve is a cutaneous nerve that innervates the area surrounding the patella and contributes to the peripatellar plexus. This nerve is target to iatrogenic injuries during a great deal of knee procedures, such as tendon harvesting, total knee arthroplasty and medial arthroscopic approaches to the knee. Lesion to this nerve can produce sensorial loss at its innervation territory. The study conducted herein aims to observe the anatomical aspects of the infrapatellar branch in cadaveric specimens. The infrapatellar branch of the saphenous nerve of 40 male cadavers was dissected with the purpose of identifying the number of branches, its relation with the patella, tibial tuberosity and sartorius muscle. The nerve was dissected and several measurements were performed with the aid of a digital caliper. Statistical analysis was performed with the MedCalc 16.1 software. The infrapatellar branch of the saphenous nerve was present in 100 % of the sample. Its mean distance from its origin to its branching point was 16.35±6.48 mm on the right and 21.94±4.31 mm on the left, with statistically significant differences (p < 0.05). A relatively safe zone for surgery was observed on the superior and medial aspect of the patella, which received less branches.

La rama infrapatelar del nervio safeno es un nervio cutáneo que inerva el área que rodea la patela y contribuye al plexo peripatelar. Este nervio es objeto de lesiones iatrogénicas durante una gran cantidad de procedimientos de rodilla, como la extracción de tendones, la artroplastía total de rodilla y los abordajes artroscópicos mediales de la rodilla. La lesión de este nervio puede producir pérdida sensorial en su territorio de inervación. El estudio realizado aquí tiene como objetivo observar los aspectos anatómicos de la rama infrapatelar en muestras de cadáveres. La rama infrapatelar del nervio safeno de 40 cadáveres masculinos se disecó con el propósito de identificar el número de ramas, su relación con la patela, la tuberosidad tibial y el músculo sartorio. Se disecó el nervio y se realizaron varias mediciones con la ayuda de un calibrador digital. El análisis estadístico se realizó con el software MedCalc 16.1. La rama infrapatelar del nervio safeno estaba presente en el 100 % de las muestras. La distancia media desde su origen hasta su punto de ramificación fue de 16,35±6,48 mm a la derecha y de 21,94±4,31 mm a la izquierda, con diferencias estadísticamente significativas (p <0,05). Se identificó una zona relativamente segura para la cirugía en el aspecto superior y medial de la patela, que recibió menos ramas.

Microanatomy of the nerve to iliacus muscle and its clinical significance / Microanatomía del nervio del músculo ilíaco y su importancia clínica

The iliacus muscle, arising from iliac fossa is innervated chiefly by nerves to iliacus and femoral nerve. The tendon of iliacus muscle in the caudal part fuses with the tendon of psoas major muscle to form iliopsoas tendon As the iliacus/iliopsoas is responsible for flexing of the thigh and the forward tilting of the pelvis, body posture, Olympic lifts, daily activities like walking and running, so impairment of above functions, due to spinal cord injury or injury to nerves to iliacus, remained a grey area to explore manifestation of nerve lesions at fascicular level. Therefore an experimental study was designed to map the complex fascicular pathways suffering from splits, fusions and multiplexing coupled with measurement of distances of closely sampled histological slides. Tracking, correlation and interpretation of fascicles, in these slides of a cropped femoral nerve in iliacus region from a 70 year old female cadaver were analyzed. The study resulted in three schematic models of fascicular pathways in 3 nerves to iliacus and 2 tabular models of 2 remaining nerves to iliacus revealing complete picture of fascicles interrupted by dynamic transformational processes. These results would facilitate MRI neurographic interpretation at fascicular level and neurosurgical treatment through identification. The fascicular identification and setup would also discover anatomical complications and location of injury. Besides the huge data volume evolved off this experiment, the study would not only open up grey area for neuroanatomical research but also would revolutionize the neurosurgical repair and grafting of nerves to iliacus at fascicular level.

El músculo ilíaco, que se inserta en la fosa ilíaca, está inervado principalmente por los nervios ilíaco y femoral. El tendón del músculo ilíaco en la parte caudal se fusiona con el tendón del músculo psoas mayor para formar el tendón del músculo iliopsoas. Los músculos ilíaco e iliopsoas son responsables de la flexión del muslo y la inclinación hacia delante de la pelvis, la postura del cuerpo, los levantamientos olímpicos, las actividades diarias como caminar y correr, por lo que el deterioro de las funciones anteriores, debido a lesiones de la médula espinal o de los nervios ilíacos, constituyen una dificultad para explorar la manifestación de lesiones nerviosas a nivel fascicular. Por lo tanto, se diseñó un estudio experimental para mapear las complejas vías fasciculares que presentan divisiones, fusiones y multiplexación, junto con medición en muestras histológicas. Se analizó el seguimiento, correlación y la interpretación de los fascículos en muestras de secciones del nervio femoral en la región ilíaca de un cadáver femenino de 70 años. Se obtuvieron tres modelos esquemáticos de vías fasciculares en 3 ramos del nervio ilíaco y dos modelos tabulares de los 2 ramos nerviosos restantes del nervio ilíaco, que muestran una imagen completa de los fascículos interrumpidos por procesos de transformación dinámica. Estos resultados facilitarían la interpretación neurográfica de la resonancia nuclear magnética a nivel fascicular y el tratamiento neuroquirúrgico a través de su identificación. La identificación y configuración del fascículo también permitirían descubrir complicaciones anatómicas y la localización de la lesión. Además del enorme volumen de datos que se desprendió de este estudio, éste no solo contribuiría a la investigación neuroanatómica, sino también puede aportar a la reparación neuroquirúrgica y al injerto de nervios al músculo ilíaco a nivel fascicular.

Ramos de inervación y distribución del nervio femoral en el músculo cuádriceps femoral de individuos brasileños / Innervation branches and distribution of the femoral nerve in the quadriceps femoral muscle in Brazilian individuals

El nervio femoral (NF) se describe originándose desde el plexo lumbar (L2, L3 y L4) y en su recorrido emite ramos destinados a cada una de las porciones del músculo cuádriceps femoral (mCF), los cuales nacen de forma aislada o bien, a partir de troncos comunes. El detalle de la distribución del NF en el mCF, permite disminuir riesgos asociados a diferentes intervenciones quirúrgicas llevadas a cabo en la zona anterior del muslo. Con el propósito describir la distribución del NF en los componentes del mCf. Se utilizaron 15 miembros inferiores formolizados, 10 del lado izquierdo y 5 del lado derecho, de individuos adultos, Brasileños, localizados en los Laboratorios de Anatomía de la Universidade Estadual de Ciências da Saúde de Alagoas (UNCISAL), Maceió, Brasil. El NF se clasificó en cuatro tipos de acuerdo a su ramificación y distribución. El Tipo II se subdividió en 3 subtipos y se presentó en 60 % de las muestras y el tipo III en 20 %. El NF se dividió de medial a lateral hasta en 5 ramos (R1,R2,R3,R4,R5), donde el R1 fue el más medial. El R1 dio origen en promedio a 2,47 ramos secundarios (Rs) y a 2,58 ramos terciarios (Rt), en 13,3 % el R1 no emitió Rs. En 73,3 % inervó a sólo a un componente del mCF; el R2 dio origen en promedio a 3,93 Rs y a 3,58 Rt. En 26,7 % inervó a sólo a un componente del mCF; el R3 dio origen en promedio a 3,33 Rs y a 2,0 Rt. En 80 % inervó a sólo a un componente del mCF. La distribución de R4 y R5 se muestran en el texto. Resultados biométricos de origen, diámetro y longitud de los ramos mencionados son mostrados en tablas. Los datos obtenidos en esta investigación complementan el conocimiento de la anatomía regional, pudiendo ser utilizados por la clínica quirúrgica y para efectuar tratamientos que mejoren trastornos neurológicos que afectan a la región.

The femoral nerve (FN) is described as originating from the lumbar plexus (L2, L3 and L4) and in its course it emits branches destined to each one of the quadriceps femoral muscle (QFm), which are originated in an isolated way or, from common trunks. The detail of the distribution of the FN in the QFm, allows to diminish risks associated with different surgical interventions carried out in the anterior thigh area. With the purpose of describing the distribution of FN in the QFm components. Fifteen formalized lower limbs were used, 10 on the left side and 5 on the right side of adult individuals, Brazilians, located in the Anatomy Laboratories of the State University of Ciências da Saúde de Alagoas (UNCISAL) , Maceió, Brazil. The FN was classified into four types according to its branch and distribution. Type II was subdivided into 3 subtypes and presented in 60 % of the samples and type III in 20 %. The FN was divided from medial to lateral in 5 branches (B1, B2, B3, B4, B5), where B1 was the most medial. The B1 gave rise to an average of 2.47 secondary branches (sB) and to 2.58 tertiary branches (tB), in 13.3 % the B1 did not emit sB. In 73.3 %, only one component of the QFm was invested; B2 gave rise to an average of 3.93 sB and 3.58 tB. In 26.7 %, it invested only one component of the QFm; B3 gave rise to an average of 3.33 sB and 2.0 tB. In 80 %, it invested only one component of the QFm. The distribution of B4 and B5 are shown in the text. Biometric results of origin, diameter and length of the mentioned branches are shown in tables. The data obtained in this research complements the knowledge of the regional anatomy, being able to be used by the surgical clinic and to carry out treatments that improve neurological disorders that affect the region.