Lumbar Plexus Research Articles

Comparative study lumbar plexus block and lumbar erector spinae plane block for postoperative pain relief after proximal femoral nail for proximal femoral fractures.

The clinical outcomes (time to ambulation, length of stay, and home discharge) after proximal femoral nail (PFN) for proximal femoral fractures (PFF) is dependent on successful pain management. Currently, the lumbar erector spinae plane block (LESPB) is in vogue and is associated with favorable outcomes in the postoperative period. Our study aimed to evaluate whether a LESPB provided equivalent analgesia and clinical outcomes as compared to LPB in PFN for PFF. We compared LPBs [L] with LESPBs [E], with 30 patients in each group, performed from June 2020 to June 2021 for PFN in PFF's. The primary outcome of this study was the average NRS pain scores over 24 hours postoperatively. Secondary outcomes included pain scores at different time points over 24 hours, opioid consumption between the groups at 24 hours postoperatively, time for request of first parenteral analgesia, quadriceps weakness and adverse events. The average pain scores over 24 hours were better in the LESPB group as compared to the LPB group (p = 0.02). Further, only n = 5 (30%) of patients in the LESPB group required opioids, while n = 13 (43.333%) of patients in the LPB group required opioids. Moreover, the median time for request of first parenteral analgesia was 615 (480-975) minutes, weakness of quadriceps function occurred in 2 patients in the L group, which recovered at 3rd and 5th month, respectively, with no incidences of hemodynamic instability and respiratory complications. This trial demonstrated that single bolus LESPB is superior to LPB in terms of analgesic outcomes, has low adverse events, and is an agreeable substitute for patients with PFF undergoing a PFN.

Use of Wiltse approach in lumbar plexus schwannoma: A technical note.

Lumbar plexus schwannomas are a rare occurrence in neurosurgery, with few reported cases and no standard surgical approach. This study describes a successful surgical resection with no complications using the Wiltse approach. Patient presented with an intra-psoas tumor suggesting schwannoma. We described the surgical technique involved step by step. The patient recovered from the surgery with no complications. The anatomopathological examination confirmed the schwannoma diagnosis. The post operatory magnetic resonance imaging showed complete resection. This study shows that the use of Wiltse approach, mainly used for classical herniated disc extraforaminal, can be used successfully on Lumbar plexus schwannomas.

Position of lumbar plexus nerves in the psoas major: Application to transpsoas approaches to the lumbar spine.

Far lateral interbody fusion is a minimally invasive operating technique. However, the incidence of postoperative neurological complications is high, and some scholars question its safety. This study describes the neuroanatomical features and spatial orientation within the psoas major. Ten embalmed male cadavers were selected and the left psoas major was dissected. Subsequently, the area between the anterior and the posterior edges of the vertebral body was divided into three equal zones. The nerves' distribution, number, and spatial orientation of the L1/2 to L4/5 intervertebral discs were examined. A caliper was used to measure the diameter of the nerve. The safety zone of the L1/2 intervertebral disc level is located in zone I and II, the relative safe zones of the L2/3 and L4/5 intervertebral discs are located in zone II, and the safety zone of the L3/4 intervertebral disc level is located in the caudal side of zone II. The genitofemoral nerve exits the psoas major in a co-trunk or two-branch pattern, and its exit point was distributed between the L3 and L4 vertebral bodies, mainly at the L3/4 intervertebral disc level. The sympathetic ganglia in the psoas major appeared only in zone I at the L2/3 intervertebral disc level. This is a systematic anatomical study that describes the nerves of the psoas major. Spine surgeons can use this study-which consists of important clinical implications-for preoperative planning, and thus, reduce the risk of nerve injury during surgery.

Importance of fasting abbreviation and analgesia in the satisfaction and recovery of elderly patients with hip and femur fractures. retrospective study with 1,001 patients

Background and objectives: There are several ways to assess patient satisfaction, as it is a standard indicator of the quality of care provided. The aim of this study was to evaluate whether the abbreviation of fasting with 200 ml CHO, the intake of the same beverage in the PACU, the return to oral feeding in the ward, and postoperative analgesia can improve comfort and satisfaction with anesthesia in elderly patients. with hip and femur fracture. Methods: A retrospective trial carried out in a Brazilian public health hospital (SUS), with 1,001 patients physical status ASA I-III submitted to hip and femur fracture surgery. The following items were evaluated: preoperative fasting time, evaluation of thirst and hunger upon arrival in the operating room, time of CHO administration in the PACU, time of reintroduction of oral feeding in the ward, and at this moment, the degree of satisfaction with the anesthetic conduct, abbreviation of fasting and early feeding. A satisfaction assessment was performed with YES and NO answers regarding the pre-anesthetic visit, the fasting abbreviation, the use of CHO in PACU, refeeding in the ward, and postoperative analgesia. Family members were also asked to return immediately to the ward, without intravenous hydration and without going through the ICU. Results: All patients had the fasting abbreviation between 1:20 h and 4:00 h. None of the 1,001 patients reported being thirsty when they arrived in the operating room, against only 26 patients reporting being hungry. The time of administration of dextrinomaltose in PACU ranged from 20 minutes to 5:45 h, and the reintroduction of oral feeding in the ward ranged from 4 h to 8:15 h. Analgesia with lumbar plexus block with a neurostimulator and levobupivacaine before or after providing mean analgesia of 22±4 h, with a minimum time of 13 h and a maximum of 34 h. All patients were able to be discharged from the hospital on the second postoperative day. Conclusion: This study with 1,001 patients clearly shows that in hospitalized elderly, the liberal use of CHO before surgery and immediately in PACU, and better quality analgesia is an easy and practical way to increase patient comfort and satisfaction with anesthesia care and with better outcomes.

Deep posterior gluteal compartment block for regional anaesthesia of the posterior hip: a proof-of-concept pilot study.

Various regional anaesthesia approaches to branches of the anterior lumbar plexus have been proved effective in providing analgesia in hip surgery. However, some patients still experience significant residual posterior hip pain attributed to the posterior nerve supply of the hip. This not only suggests that anterior approaches may not always provide sufficient pain relief, but also that the blocking of major nerves supplying the posterior pericapsular region is needed. We present an ultrasound-guided technique to block all major nerves supplying the posterior capsule of the hip joint. The optimal target area was determined by ultrasound imaging, cross-sectional digitised anatomy, and cadaver research, and was found in the deep gluteal compartment. Furthermore, this posterior pericapsular deep-gluteal block was evaluated in two patients. The spread of dye in the cadaver was observed deep to the gluteus maximus and in between the quadratus femoris and piriformis muscles, and conformed to the presumed location during the ultrasound procedure. It included all major supplying nerves to the posterior hip capsule, that is the superior gluteal nerve, nerve to quadratus femoris and sciatic nerve. In both patients where this posterior pericapsular deep-gluteal block was applied the pain was substantially reduced (numeric rating scale: 4 to 1 and 7 to 1). We present a successful ultrasound-guided technique targeting the deep gluteal compartment to block all major nerves supplying the hip joint's posterior capsule. This posterior pericapsular deep-gluteal block can be applied as an additional block in hip surgery, with also a possible role in chronic hip pathology.

Total Spinal after Posterior Lumber Plexus Block, Case Report

Patients can undergo lower extremity surgery by using the lumbar plexus block (LPB) technique. However, compared with central block, LPB problems were complex. For lower limb procedures, psoas compartment block is a suitable regional anaesthesia approach in place of central neuraxial blockade. As a peripheral nerve block, it is considered less dangerous than a central neuraxial block. However, it might result in some severe issues. Here, we describe a rare side effect of total spinal anaesthesia following psoas compartment block guided by a peripheral nerve stimulator.

Safety and Efficacy of Combined Lumbar Plexus, Sciatic Nerve, Femoral Nerve Blocks in Failed Spinal Anaesthesia for Lower Limb Surgeries: A Prospective Clinical Study

Safety and Efficacy of Combined Lumbar Plexus, Sciatic Nerve, Femoral Nerve Blocks in Failed Spinal Anaesthesia for Lower Limb Surgeries: A Prospective Clinical Study

A new approach for ultrasound-guided lumbar plexus block: ultrasound-guided paravertebral LPB.

A new approach for ultrasound-guided lumbar plexus block: ultrasound-guided paravertebral LPB.

Variations in the Lateral Femoral Cutaneous Nerve of the Thigh in Cadavers: A Cross-sectional Study

Introduction: The Lateral Femoral Cutaneous Nerve (LFCN) is formed by the union of the dorsal divisions of the ventral rami of the third and fourth lumbar spinal nerves. The nerve is a sensory branch of the lumbar plexus and supplies the upper lateral aspect of the thigh. It is often trapped between the inguinal ligament and the anterior superior iliac spine, causing paraesthesia in the supplied area, known as meralgia paraesthetica. The LFCN has been shown to exhibit significant variations in formation and course, which can affect the efficacy of nerve blocks administered in the affected area. Aim: To study the variations in the formation of the LFCN in the pelvis of cadavers. Materials and Methods: A cross-sectional study was conducted at Government Medical College, Kota, Rajasthan, from January 2021 to January 2023. The study involved 25 formalin-embalmed cadavers (20 male and 5 female) obtained from the anatomy departments of various medical colleges in Rajasthan. All human cadaveric specimens with well-preserved lumbar plexus, regardless of gender, were included. The lumbar plexus was dissected bilaterally, and the formation and any variations of the LFCN were observed and recorded using digital photography. The obtained data was segregated by gender and side, and Chi-square test was applied to analyse the data using Statistical Package for Social Sciences (SPSS) version 25.0. Results: The LFCN originated from L2 and L3 in 47 (94%) specimens. We observed the absence of the LFCN, double LFCN, and sole origin from L2 only in 1 (2%) case each. Additionally, the origin of the LFCN from the femoral nerve was observed in one specimen. Conclusion: The variations noted in the present study would be valuable for surgeons and anaesthetists planning skin grafts and nerve blocks in the thigh area, as well as in transpsoas surgeries.

Ultrasound-Guided Peripheral Nerve Blocks for Hip Surgery: A Concise Perspective.

Ultrasound implementation for the facilitation of peripheral nerve blocks is well established. Ultrasound-guided lumbar plexus, femoral, fascia iliaca and supra-inguinal fascia iliaca compartment, pericapsular nerve group and quadratus lumborum nerve blocks have been employed for analgesia purposes in hip surgery. The combination of motor-sparing regional anesthesia strategies for optimal postoperative pain control with recovery protocols targeting to early and safe patients' mobilization constitute the current dogma of orthopedic surgery. Therefore, this editorial sets out to revisit the role of peripheral nerve blocks in postoperative pain management of hip surgery patients, under the prism of current orthopedic practice.

Retracted: Continuous Lumbar Plexus Block under the Guidance of the "Shamrock Method" Ultrasound: Analgesic Effects and Hemodynamic Effects after Total Knee Arthroplasty in Elderly Patients.

[This retracts the article DOI: 10.1155/2021/3531236.].

Supra-inguinal Fascia Iliaca Block and the Obturator Nerve Obsession

To the Editor, Anatomic block efficacy of lumbar plexus elements is based upon the involvement of the obturator nerve. However, despite the anatomic location of the obturator nerve and improbable translocation of local anesthetic beyond the confinement of the fascia iliacus plane [1], investigators struggle to study extensively, exhaustively, and try to explicitly describe the means and mechanism to block the obturator nerve [2]. Our anatomical dissections reveal three important dissimilar fascial planes (figure 1a). The quadratus lumborum, the fascia iliaca, and the circum-psoas planes are isolated from each other with tight fascial attachments [Figure 1b], impeding the dissemination of local anaesthetic agents unless inadvertently perforating the fascia. Further exploration revealed the femoral, lateral femoral cutaneous, obturator nerves and the lumbosacral trunk emerge from the lateral and medial of the psoas muscle respectively, and exits the psoas fascia (figure 1a,1b, and 1c) to take their respective course. The obturator nerve might further arise in a separate muscular fold (Figure 1c). However, if the obturator nerve needs to be blocked, two we recommend two alternatives; We presume that with injections deep to the psoas sheath, the plausibility of involvement of all the nerves of the lumbar plexus (lateral femoral cutaneous nerve, femoral nerve, and ON) exists, as reported in a case series [3] and the obturator nerve needs to be blocked separately after a supra-inguinal fascia iliaca block.

Thoracolumbar fractures after the 2023 Türkiye earthquake and controversial mechanism of occurrence.

Earthquakes are devastating events that may severely injure the human body. The spine is one of the important parts of the human body that may be affected by earthquake trauma. The aim of this study is to focus on thoracolumbar fractures secondary to the 2023 Turkey Earthquake. The data of 15 patients who were affected by the earthquake, rescued from the rubble, and subsequently treated for spinal fractures in our department were reviewed retrospectively. The clinical, radiological, and surgical features of the patients were recorded, and the outcomes were investigated. Among the 15 patients, 12 were female, and 3 were male. Their ages ranged from 22 to 79 years. The average duration of being trapped under debris was 4.7 hours. According to the Frankel classification, 12 patients (80%) were categorized as Frankel E, 2 patients (13.3%) as Frankel A, and 1 patient (6.6%) as Frankel C. Of these patients, 6 underwent surgical treatment, while a total of 9 patients received conservative treatment. Multiple vertebral fractures were identified in 4 patients. While 3 patients with multiple fractures were treated conservatively, 1 patient underwent surgery due to an L1 fracture. All surgeries consisted of spinal canal de-compression and spinal instrumentation. Among patients without thoracolumbar junction fractures, 1 had a T8 fracture, 1 had an L4 fracture, and 1 had a sacral fracture along with an accompanying lumbar plexus injury. Thoracolumbar fractures are frequently observed after earthquakes. However, the exact mechanism of these fractures is not well known. Surgical management should be reserved for patients with progressive neurological deficits, while conservative treatment is the option for stable fractures.

Multilevel tandem spondylolisthesis associated with a reduced "safe zone" for a transpsoas lateral lumbar interbody fusion at L4–5

The aim of this study was to investigate the effect of degenerative spondylolisthesis (DS) on psoas anatomy and the L4-5 safe zone during lateral lumbar interbody fusion (LLIF). In this retrospective, single-institution analysis, patients managed for low-back pain between 2016 and 2021 were identified. Inclusion criteria were adequate lumbar MR images and radiographs. Exclusion criteria were spine trauma, infection, metastases, transitional anatomy, or prior surgery. There were three age and sex propensity-matched cohorts: 1) controls without DS; 2) patients with single-level DS (SLDS); and 3) patients with multilevel, tandem DS (TDS). Axial T2-weighted MRI was used to measure the apical (ventral) and central positions of the psoas relative to the posterior tangent line at the L4-5 disc. Lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and PI-LL mismatch were measured on lumbar radiographs. The primary outcomes were apical and central psoas positions at L4-5, which were calculated using stepwise multivariate linear regression including demographics, spinopelvic parameters, and degree of DS. Secondary outcomes were associations between single- and multilevel DS and spinopelvic parameters, which were calculated using one-way ANOVA with Bonferroni correction for between-group comparisons. A total of 230 patients (92 without DS, 92 with SLDS, and 46 with TDS) were included. The mean age was 68.0 ± 8.9 years, and 185 patients (80.4%) were female. The mean BMI was 31.0 ± 7.1, and the mean age-adjusted Charlson Comorbidity Index (aCCI) was 4.2 ± 1.8. Age, BMI, sex, and aCCI were similar between the groups. Each increased grade of DS (no DS to SLDS to TDS) was associated with significantly increased PI (p < 0.05 for all relationships). PT, PI-LL mismatch, center psoas, and apical position were all significantly greater in the TDS group than in the no-DS and SLDS groups (p < 0.05). DS severity was independently associated with 2.4-mm (95% CI 1.1-3.8 mm) center and 2.6-mm (95% CI 1.2-3.9 mm) apical psoas anterior displacement per increased grade (increasing from no DS to SLDS to TDS). TDS represents more severe sagittal malalignment (PI-LL mismatch), pelvic compensation (PT), and changes in the psoas major muscle compared with no DS, and SLDS and is a risk factor for lumbar plexus injury during L4-5 LLIF due to a smaller safe zone.

Effects of dexmedetomidine combined with ropivacaine on the treatment of lumbar plexus sciatic nerve block in elderly patients with lower limb fractures

To further explore the effects of dexmedetomidine combined with ropivacaine in the treatment of lumbar plexus sciatic nerve block in elderly patients with lower limb fractures. 98 patients with lower limb fractures enrolled from January 2020 to January 2022 were randomly divided into the study and control groups, with 49 cases in each group. The study group received dexmedetomidine combined with ropivacaine for nerve block; while the control group received ropivacaine for nerve block. The anesthesia effect (duration time of onset and duration time of sensory block and motor block), heart rate, blood pressure, pain score, and adverse effects were compared between the study and control groups. Patients in the study group given dexmedetomidine combined with ropivacaine for lumbar plexus sciatic nerve block had a longer duration time of sensory block and motor block than the control group, showing a better anesthetic effect. The levels of mean arterial blood pressure (MAP) and heart rate (HR) in the study group at T1, T2, T3, T4, and T5 were significantly lower than that in the control group. The pain scores of the study group was lower than that of the control group, indicating the effects of dexmedetomidine combined with ropivacaine on reducing pain. Besides, the study group showed an adverse reaction incidence of 4.08%, which was slightly higher than that of the control group, with an index of 2.04%, without statistically significant difference. Dexmedetomidine combined with ropivacaine can enhance the effect of ropivacaine block, improve the heart rate index, and reduce patients’ pain, which is one of the reliable schemes in clinical practice for lumbar plexus sciatic nerve block.

Treatment of Single Level Lumbar Spondylolisthesis with Lumbar Interbody Fusion via Oblique Lateral Approach (OLIF)

Objectives: To investigate the effect of lumbar interbody fusion via the oblique lateral approach (OLIF) in the treatment of single level lumbar spondylolisthesis. Methods: Retrospective analysis was made on 32 cases of single level lumbar spondylolisthesis treated by lumbar interbody fusion via the oblique lateral approach from July 2020 to July 2021. 14 males and 18 females; the age was (66.5 ± 11.5) years (55 - 82 years). 1) The operation time, intraoperative blood loss and complications were recorded; 2) the scores of visual analog scale. VAS and Oswestry disability index (ODI) of low back pain and lower limb pain were collected before operation and at the last follow-up; by observing the imaging data, the height of the intervertebral space, the anterior convex angle of the intervertebral space, the anterior convex angle of the lumbar spine, the sagittal diameter of the dural sac and the spondylolisthesis were measured. Results: All patients successfully completed the operation, the average operation time was (103.9 ± 21.1) min, the average intraoperative bleeding volume was (72.3 ± 16.4) ml. There was no vascular injury during the operation, no infection occurred in all surgical incisions, and Class I/A healing was achieved. The VAS scores of low back pain and leg pain before operation and at the last follow-up were lower than those before operation, and the difference was statistically significant (P the height of intervertebral foramen and the sagittal diameter of dural sac were greater than those before operation, with statistically significant differences (P than that before operation, with a statistically significant difference (P ureteral injury, retrograde ejaculation, intestinal and lumbar plexus injury. Conclusion: The early clinical effect of OLIF in the treatment of single level lumbar spondylolisthesis is significant. This surgical method is minimally invasive, safe and effective, which can significantly reduce the amount of intraoperative bleeding and reduce the risk of postoperative complications. Its main working principle is to make the annulus fibrosus, posterior longitudinal ligament and ligamentum flavum shrink and recover the height of the intervertebral space through decompression, loosening and stretching of the intervertebral space, so as to achieve the reduction of the slipped vertebral body, increase the height of the intervertebral foramen Enlarge the spinal canal volume and eliminate dynamic compression to play an indirect decompression role, improve the symptoms of low back and leg pain, and reconstruct the stability of the spine through interbody fusion.

Postoperative Lumbar Plexopathy Secondary to Retroperitoneal Liposarcoma: A Case Report

Liposarcoma is a rare malignancy that usually originates in the extremities or the retroperitoneum. The lumbar plexus, a complex neural network formed by divisions of the first four lumbar roots, penetrates the psoas muscle before it exits the pelvis. Owing to their anatomical proximity, neoplasms in the vicinity of the psoas muscle may involve the lumbar plexus. We report a case of postoperative lumbar plexopathy involving the posterior divisions of the lumbar plexus, following the resection of a recurrent retroperitoneal liposarcoma located in the dorsal aspect of the psoas muscle. A 50-year-old man visited a rehabilitation clinic for an evaluation of proximal weakness of the unilateral lower extremity after resection of a recurrent liposarcoma of the left psoas muscle. Physical examination showed weakness of left hip flexion and knee extension accompanied by sensory loss in the left anteromedial thigh and the medial lower leg. An electrophysiological study revealed left lumbar plexopathy with selective involvement of the posterior divisions of the lumbar plexus. The patient could walk independently without a walking aid on level surfaces while he underwent exercise therapy. A comprehensive evaluation, including a physical examination, the use of imaging modalities such as computed tomography for anatomical characterization, and electrophysiological studies, is important for accurate diagnosis.

Lumbar Plexus Palsy Caused by Massive Psoas Hematoma Related to Vertebral Compression Fracture in a Patient with Liver Cirrhosis.

Osteoporotic vertebral compression fractures (VCFs) are common injuries in elderly patients and are usually stable because only the anterior column is involved. However, neurological deterioration may complicate osteoporotic VCFs, and most of them are related to canal invasion. Liver cirrhosis (LC) and its related complications have been identified as risk factors for an increased bleeding tendency, which, in turn, is associated with increased morbidity and mortality risks. We herein present a rare case of an osteoporotic VCF and a massive psoas hematoma that resulted in lumbar plexus palsy in a patient with LC after a stable-type spinal injury. To our knowledge, this is the first reported case of lumbar plexus palsy attributed to a liver-cirrhosis-related massive psoas hematoma and a stable VCF after minor trauma. This case highlights the potential risk of severe neurological deficits related to this type of common and seemingly trivial injury. The possible pathophysiological mechanisms are discussed and the relevant literature is reviewed.

Neurological Complications Associated With SARS-CoV-2 Infection: A Single-Centre Experience.

The clinical presentation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can range from mild or moderate disease (80% of the cases) to severe disease (15%) requiring oxygen support, and critical disease (5%), associated with acute respiratory distress syndrome and admission to the intensive care unit (ICU).In critically ill patients, prone positioning can be used to optimize oxygenation. Although there is a favourable response to this strategy, being a life-saving measure, additional associated complications may appear, including compressive neuropathies.Despite respiratory affection being more common, SARS-CoV-2 infection can also attack othersystems and can, under certain conditions, affect the central or peripheral nervous system. It has been described that neurological manifestations can result from the neuroinvasive properties of the SARS-CoV-2 or as an indirect consequence of multiorgan dysfunction. We intend to report the patients who presented with neurological complicationsassociated with coronavirus disease 2019 (COVID-19) and/or complications of its treatment, followed in our physical and rehabilitation medicine (PRM) service. A retrospective analysis of patients admitted to the PRM ward with outpatient consultation in the context of post-COVID-19 statusbetween April 2020 and November 2021 (the period of the highest prevalence of infection) was carried out. Patients with neurological complications after SARS-CoV-2 infectionandconsequentlya decline in previous functionality were identified. Thirteen patients (23.6%)admitted to the PRM ward had peripheral neurological complications, documented by electroneuromyography, includingGuillain-Barré syndrome, sensory-motor polyneuropathy, peroneal nerve injury, femoral nerve injury, and lumbar plexus injury.The neurological complications of the patients followed in a post-COVID-19 consultation were also evaluated. Eight patients (20%) reported neurological sequelae. Five patients presented peripheral nerve damage (peroneal, accessory, ulnar, and recurrent laryngeal) of undefined aetiology, diagnosed after the acute phase of hospitalization. Two patients had COVID-19 infection followed by ischemic stroke (vertebrobasilar and middle cerebral artery), requiring hospitalization in the acute phase. One patient had COVID-19 infectionfollowed by longitudinal myelitis, with positive anti-myelin oligodendrocyte glycoprotein (MOG). All patients required follow-up by the rehabilitation team with partial recovery of deficits. All patients admitted to the PRM ward with neurological manifestations had critical disease and symptoms compatible with peripheral nervous system involvement. Patients admitted to the PRM consultation had different levels of viral disease severityand had sequelae related to peripheral and central nervous system disorders. Identifying the aetiology of these injuries is essential for us to act on their prevention, particularly with regard to indirect complications, such as compressive neuropathies.It will be necessary to maintain the follow-up of these patients to understand the evolution of the neurological consequences associated with COVID-19.

Female Sex and Supine Proximal Lumbar Lordosis Are Associated With the Size of the LLIF "Safe Zone" at L4-L5.

Retrospective chart review. Identify demographic and sagittal alignment parameters that are independently associated with femoral nerve position at the L4-L5 disk space. Iatrogenic femoral nerve or lumbar plexus injury during lateral lumbar interbody fusion (LLIF) can result in neurological complications. The LLIF "safe zone" is the anterior half to two third of the disk space. However, femoral nerve position varies and is inconsistently identifiable on magnetic resonance imaging. The safe zone is also narrowest at L4-L5. An analysis of patients with symptomatic lumbar spine pathology and magnetic resonance imaging with a visibly identifiable femoral nerve evaluated at a single large academic spine center from January 1, 2017, to January 8, 2020, was performed. Exclusion criteria were transitional anatomy, severe hip osteoarthritis, coronal deformity with cobb >10 degrees, > grade 1 spondylolisthesis at L4-L5 and anterior migration of the psoas.Standing and supine lumbar lordosis (LL) and its proximal (L1-L4) and distal (L4-S1) components were measured. Femoral nerve position on sagittal imaging was then measured as a percentage of the L4 inferior endplate. A stepwise multivariate linear regression of sagittal alignment and LL parameters was then performed. Data are written as estimate, 95% CI. Mean patient age was 58.2±14.7 years, 25 (34.2%) were female and 26 (35.6%) had a grade 1 spondylolisthesis. Mean femoral nerve position was 26.6±10.3% from the posterior border of L4. Female sex (-6.6, -11.1 to -2.1) and supine proximal lumbar lordosis (0.4, 0.1-0.7) were independently associated with femoral nerve position. Patient sex and proximal LL can serve as early indicators of the size of the femoral nerve safe zone during a transpsoas LLIF approach at L4-L5.