BACKGROUND: Together with an increased interest in minimally invasive lateral transpsoas approach to the lumbar spine goes a demand for detailed anatomical descriptions of the lumbar plexus. Although definitions of safe zones and essential descriptions of topographical anatomy have been presented in several studies, the existing literature expects standard appearance of the neural structures. Therefore, the aim of this study was to investigate the variability of the extrapsoas portion of the lumbar plexus in regard to the lateral transpsoas approach. METHODS: A total of 260 lumbar regions from embalmed cadavers were utilized in this study. The specimens were dissected as per protocol and all nerves from the lumbar plexus were morphologically evaluated. RESULTS: The most common variation of the iliohypogastric and ilioinguinal nerves was fusion of these two nerves (9.6%). Nearly in the half of the cases (48.1%) the genitofemoral nerve left the psoas major muscle already divided into the femoral and genital branches. The lateral femoral cutaneous nerve was the least variable one as it resembled its normal morphology in 95.0% of cases. Regarding the variant origins of the femoral nerve, there was a low formation outside the psoas major muscle in 3.8% of cases. The obturator nerve was not variable at its emergence point but frequently branched (40.4%) before entering the obturator canal. In addition to the proper femoral and obturator nerves, accessory nerves were present in 12.3% and 9.2% of cases, respectively. CONCLUSION: Nerves of the lumbar plexus frequently show atypical anatomy outside the psoas major muscle. The presented study provides a compendious information source of the possibly encountered neural variations during retroperitoneal access to different segments of the lumbar spine.

Center for Endoscopic Surgical and Clinical Anatomy 2nd Faculty of Medicine Charles University Prague Czech Republic

Department of Anatomy 2nd Faculty of Medicine Charles University Prague Czech Republic

Department of Health Care Studies College of Polytechnics Jihlava Czech Republic

Department of Neurology 3rd Faculty of Medicine Charles University and University Hospital Kralovske Vinohrady Prague Czech Republic

Department of Traumatology University of Szeged Szeged Hungary

Research Centre Faculty of Health Studies Jan Evangelista Purkyne University in Usti Nad Labem Usti Nad Labem Czech Republic

Spinal Surgery Unit Oxford University Hospitals NHS Foundation Trust Oxford UK

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Ahmadian A, Deukmedjian AR, Abel N, Dakwar E, Uribe JS (2013) Analysis of lumbar plexopathies and nerve injury after lateral retroperitoneal transpsoas approach: diagnostic standardization. J Neurosurg Spine 18:289–297 PubMed

Anloaguae PA, Huijbregts P (2009) Anatomical variations of the lumbar plexus: a descriptive anatomy study with proposed clinical implications. J Manual Manipulative Med 17:E107–E114 PubMed PMC

Benglis DM, Vanni S, Levi AD (2009) An anatomical study of the lumbosacral plexus as related to the minimally invasive transpsoas approach to the lumbar spine. J Neurosurg Spine 10:139–144 PubMed

Dakwar E, Vale FL, Uribe JS (2011) Trajectory of the main sensory and motor branches of the lumbar plexus outside the psoas muscle related to the lateral retroperitoneal transpsoas approach. J Neurosurg Spine 14:290–295 PubMed

Davis TT, Bae HW, Mok JM, Rasouli A, Delamrter RB (2011) Lumbar plexus anatomy within the psoas muscle: implications for the transpsoas lateral approach to the L4–L5 disc. J Bone Joint Surg Am 93:1482–1487 PubMed

Geh N, Schultz M, Yang L, Zeller J (2015) Retroperitoneal course of iliohypogastric, ilioinguinal, and genitofemoral nerves: a study to improve identification and excision during triple neurectomy. Clin Anat 28:903–909 PubMed

Guerin P, Obeid I, Bourghli A, Masquefa T, Luc S, Gille O, Pointillart V, Vital JM (2012) The lumbosacral plexus: anatomic considerations for minimally invasive retroperitoneal transpsoas approach. Surg Radiol Anat 34:151–157 PubMed

Haladaj R, Wysiadecki G, Macchi V, de Caro R, Wojdyn M, Polguj M, Topol M (2018) Anatomic variations of the lateral femoral cutaneous nerve: remnants of atypical nerve growth pathways revisited by intraneural fascicular dissection and a proposed classification. World Neurosurg 188:E687–E698 PubMed

Iwanaga J, Simonds E, Schmacher M, Kikuta S, Watanabe K, Tubbs RS (2019) Revisiting the genital and femoral branches of the genitofemoral nerve: suggestion for a more accurate terminology. Clin Anat 32:458–463 PubMed

Klaassen Z, Marshall E, Tubbs RS, Louis RG Jr, Wartmann CT, Loukas M (2011) Anatomy of the ilioingunal and iliohypogastric nerves with observations of their spinal nerve contributions. Clin Anat 24:454–461 PubMed

Rab M, Ebmer J, Dellon AL (2001) Anatomic variability of the ilioinguinal and genitofemoral nerve: implications for the treatment of groin pain. Plast Reconstr Surg 108:1618–1623 PubMed

Tomaszewski KA, Popieluszko P, Henry BM, Roy J, Sanna B, Kijek MR, Walocha JA (2016) The surgical anatomy of the lateral femoral cutaneous nerve in the inguinal region: a meta-analysis. Hernia 20:649–657 PubMed PMC

Turgut M, Protas M, Gardner B, Oskouian RJ, Loukas M, Tubbs RS (2017) The accessory obturator nerve: an anatomical study with literature analysis. Anat 11:121–127

Uribe JS, Arredondo N, Dakwar E, Vale FL (2010) Defining the safe working zones using the minimally invasive lateral retroperitoneal transpsoas approach: an anatomical study. J Neurosurg Spine 13:260–266 PubMed

Matejcik V (2010) Anatomical variations of lumbosacral plexus. Surg Radiol Anat 32:409–414 PubMed

Standring S (2016) Gray’s Anatomy, 41st edn. Elsevier, Philadelphia

Walker CT, Farber SH, Cole TS, Xu DS, Godzik J, Whiting AC, Hartman C, Porter RW, Turner JD, Uribe J (2019) Complications for minimally invasive lateral interbody arthrodesis: a systematic review and meta-analysis comparing prepsoas and transpsoas approaches. J Neurosurg Spine 30:446–460 PubMed

Webber RH (1961) Some variations in the lumbar plexus of nerves in man. Acta Anat 44:336–345 PubMed