Inter-Strain Differences in the Lumbar Spinal Cord Anatomy and Neuromorphology: Wistar Versus Dark Agouti Rats.

Rat strains differ in physiology, behavior, and recovery after central nervous system injury. To assess these differences, we compared the gross and local anatomy and neuromorphology of the lumbar spinal cord of the Wistar and Dark Agouti (DA) strains. The key findings include (i) distinct spatial relationships between vertebrae and spinal segments in the two strains; (ii) Wistar rats have larger volumes of spinal cord gray and white matter; (iii) DA rats have smaller total neuronal populations, thus indicating an expectation of smaller local neuronal populations; (iv) this expectation was confirmed for interneurons expressing calbindin 28 kDa. But contrary to expectations, (v) DA rats had more numerous populations of the interneurons expressing parvalbumin and a population of α-motoneurons. Consequently, these strains displayed divergent ratios in specific spinal neuronal populations. Researchers should consider these inter-strain differences when comparing data across different strains.

Morphometric Evaluation of the Thoracic and Lumbar Vertebral Canal and Spinal Cord Using Computed Tomography in Healthy Korean Shorthair Cats.

This study aimed to evaluate the spinal morphometry of the thoracic and lumbar regions in normal Korean Shorthair cats using computed tomography (CT) and to investigate the relationship with variables such as sex, age and body weight. Fifteen clinically healthy Korean Shorthair cats (eight males, seven females) from Seoul National University Veterinary Medical Teaching Hospital were included in this retrospective study. Measurements of the height, width and area of the vertebral canal and spinal cord on CT images were taken at the cranial, middle and caudal points of the thoracic and lumbar vertebrae by three observers, and the ratios of the spinal cord area to the vertebral canal area were calculated. The significance of the differences in measurements between sexes and correlations with age and body weight were analysed. The mean age of the cats was 7 years (range: 2-12 years), with a mean weight of 5.27 kg (range: 2.6-8.3 kg). The height, width and area of the vertebral canal and spinal cord were significantly greater in males than in females (p < 0.05). The ratios of the spinal cord area to the vertebral canal area showed no significant difference between sexes (p > 0.05), and no significant correlations were found between the ratios of the spinal cord area to the vertebral canal area and age or body weight. This study provides useful reference intervals for spinal morphometry in the thoracic and lumbar regions of healthy Korean Shorthair cats and investigate the relationship with variables such as sex, age and body weight. This anatomical information may assist in the diagnosis and prognosis of thoracic, lumbar vertebral and spinal cord diseases using CT.

L4-L5 anatomy classification system for lateral lumbar interbody fusion.

Lateral lumbar interbody fusion (LLIF), developed by Dr. Luiz Pimenta in 2006, allows access to the spinal column through the psoas major muscle. The technique has many advantages, such as reduced bone and muscular tissue damage, indirect decompression, larger implants, and lordosis correction capabilities. However, this technique also has drawbacks, with the most notorious being the risk of spinal pathologies due to indirect injury of the lumbar plexus, but with low rates of persistent injuries. Therefore, several groups have proposed classifications to help identify patients at a greater risk of presenting with neurological deficits. The present work proposes a classification system that relies on simple observation of easily identifiable key structures to guide lateral L4-L5 LLIF decision-making. Patients aged > 18 years who underwent preoperative magnetic resonance imaging (MRI) between 2022 and 2023 were included until 50 high-quality images were acquired. And excluded as follow Anatomical changes in the vertebral body or major psoas muscles prevent the identification of key structures or poor-quality MRIs. Each anatomy was classified as type I, type II, or type III according to the consensus among the three observers. Fifty anatomical sites were included in this study. 70% of the L4-L5 anatomy were type I, 18% were type II, and 12% were type III. None of the type 3 L4-L5 anatomies were approached using a lateral technique. The proposed classification is an easy and simple method for evaluating the feasibility of a lateral approach to-L4-L5.

Assessment of age-dependent sexual dimorphism in paediatric vertebral size and density using a statistical shape and statistical appearance modelling approach.

This work focuses on the growth patterns of the human fourth lumbar vertebra (L4) in a paediatric population, with specific attention to sexual dimorphism. The study aims to understand morphological and density changes in the vertebrae through age-dependent statistical shape and statistical appearance models, which can describe full three-dimensional anatomy. Results show that the main growth patterns are associated with isotropic volumetric vertebral growth, a decrease in the relative size of the vertebral foramen, and an increase in the length of the transverse processes. Moreover, significant sexual dimorphism was demonstrated during puberty. We observe significant age and sex interaction in the anterior vertebral body height (P = 0.005), where females exhibited an earlier increase in rates of vertebral height evolution. Moreover, we also observe an increase in cross-sectional area (CSA) with age (P = 0.020), where the CSA is smaller in females than in males (significant sex effect P = 0.042). Finally, although no significant increase in trabecular bone density with age is observed (P = 0.363), a trend in the statistical appearance model suggests an increase in density with age.

Variations of the extrapsoas course of the lumbar plexus with implications for the lateral transpsoas approach to the lumbar spine: a cadaveric study.

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.

Anatomical and biomechanical characteristics of basivertebral foramen and its clinical significance. / æ¤ŽåŸºé™è„‰å­”çš„è§£å‰–å­¦å’Œç”Ÿç‰©åŠ›å­¦ç‰¹å¾åŠå ¶ä¸´åºŠæ„ä¹‰.

Basivertebral foramen is a natural orifice in the posterior wall of the vertebral body existing in humans and mammals, through which the basal vertebral vein, branch of lumbar artery and recurrent branch of spinal nerve enter and exit the vertebral body. Basivertebral foramen changes the local microstructure of the vertebral body, resulting in cortical defect and sparse trabecular bone in the central region of the vertebral body, thus affecting its biomechanical characteristics and making its central region a "weak" area of the vertebra. Some characteristic injuries of the vertebra are related to basivertebral foramen, such as vertebral compression fracture and intervertebral cleft, vertebral burst fracture and posterior upper vertebral fracture fragment, and cement leakage during treatment. In this article, the anatomical and developmental biological characteristics of basivertebral foramen, the impact of basivertebral foramen on biomechanical characteristics, and the treatment of basivertebral foramen related vertebral diseases are reviewed, in order to provide references for the clinical diagnosis and treatment of vertebral injuries.

Topography of the medullary cone of Choloepus didactylus for locoregional anesthesia purposes.

Choloepus didactylus (two-toed sloth) is a Xenarthran mammal whose morphology has so far been little studied. Given the increasing number of sloths requiring clinical and surgical interventions, this lack of clarity regarding anatomical features and landmarks has had a negative impact on veterinary decision-making for this species. We therefore sought to describe the topography of the medullary cone (MC) of Choloepus didactylus in order to provide guidance to qualified professionals on the ideal access for locoregional anesthesia. In evaluating four specimens, radiographs and dissections revealed that Choloepus didactylus has three lumbar vertebrae and five sacral vertebrae. The lumbar intumescence is located between T14 and the cranial half of L2, the medullary cone is located between the caudal half of L2 and L3, with an average length of 2.26 cm, and the cauda equina extends from S1 to S5. Based on these anatomical findings, we propose that the lumbosacral region would be the most suitable target for epidural anesthesia in Choloepus didactylus.

Does Swimming Exercise Impair Bone Health? A Systematic Review and Meta-Analysis Comparing the Evidence in Humans and Rodent Models.

BACKGROUND: The effect of swimming on bone health remains unclear, namely due to discrepant findings between studies in humans and animal models. OBJECTIVE: The aim of this systematic review and meta-analysis is to identify the available evidence on the effects of swimming on bone mass, geometry and microarchitecture at the lumbar spine, femur and tibia in both humans and rodent animal models. METHODS: The study followed PRISMA guidelines and was registered at PROSPERO (CRD4202236347 and CRD42022363714 for human and animal studies). Two different systematic literature searches were conducted in PubMed, Scopus and Web of Science, retrieving 36 and 16 reports for humans and animal models, respectively. RESULTS: In humans, areal bone mineral density (aBMD) was similar between swimmers and non-athletic controls at the lumbar spine, hip and femoral neck. Swimmers' tibia diaphysis showed a higher cross-sectional area but lower cortical thickness. Inconsistent findings at the femoral neck cortical thickness were found. Due to the small number of studies, trabecular microarchitecture in human swimmers was not assessed. In rodent models, aBMD was found to be lower at the tibia, but similar at the femur. Inconsistent findings in femur diaphysis cross-sectional area were observed. No differences in femur and tibia trabecular microarchitecture were found. CONCLUSION: Swimming seems to affect bone health differently according to anatomical region. Studies in both humans and rodent models suggest that tibia cortical bone is negatively affected by swimming. There was no evidence of a negative effect of swimming on other bone regions, both in humans and animal models.

A Morphometric Study of Cadavers for the Anterior Approach to the Lower Lumbar Spine.

AIM: To explore the relationship between the retroperitoneal vasculature and anterior surface of the lower spine, and to establish values for aiding in prediction of the pertinence of anterior approach at the L4-L5 and L5-S1 intervertebral discs. MATERIAL AND METHODS: The study included 13 fresh human cadavers. After exploration of the abdominal cavity and removal of the visceral organs, the vasculature, and anterior spinal surface were revealed beneath the lower extension of the perirenal fascia. Morphometric measurements of the great vessels and the intervertebral discs were obtained. All measurements were analyzed and presented as mean and standard deviation. Differences in the values between sexes were assessed. RESULTS: The anterior height of the L4-L5 and L5-S1 intervertebral disc was 6.8 ± 0.81 mm and 6.7 ± 0.99 mm, respectively. The widths of the aorta, inferior vena cava, right and left common iliac arteries, and right, and left common iliac veins were 16.4 ± 3.58, 20.6 ± 3.36, 11.5 ± 2.32, 11.5 ± 2.43, 14.7 ± 3.13, and 15.5 ± 3.27 mm, respectively. The mean aortic bifurcation angle was 45.5°. The aortic bifurcation was located above the lower endplate of the L4 vertebrae in 53.8% of the cadavers. The area of the interarterial and interiliac trigones was 14.6 ± 5.33 cm < sup > 2 < /sup > and 7.1 ± 4.35 cm2, respectively. No statistically significant differences were noted between the sexes. CONCLUSION: An elaborate radiological examination of the vasculature should be performed prior to surgery to avoid unwanted vascular complications during the anterior approach. Knowing the area of the interarterial and interiliac triangles and the aortic bifurcation location could be aid in assessing the safe working zone.

The Clinical Significance of Lumbar Transverse Process Lengths Associated with Lumbosacral Transitional Vertebrae: A Landmark for Lumbar Spine Enumeration.

OBJECTIVE: This study aimed to identify which lumbar vertebral level above a lumbosacral transitional vertebra (LSTV) demonstrated the longest transverse process (TVP) lengths. METHODS: In this exploratory quantitative osteological cohort study using a digital Vernier caliper, dried human cadaveric lumbar TVPs were measured for linear horizontal length at each lumbar vertebra, left and right sides. Data collection was conducted in South Africa at the Raymond A. Dart Collection of Modern Human Skeletons and the Pretoria Bone Collection. The LSTV cohort consisted of 110 spinal columns and an LSTV-free control cohort of a sex-balanced randomized selection of 30 male and 30 female spinal columns. RESULTS: Compared with the control cohort, the LSTV cohort demonstrated longer TVPs for every vertebral level, particularly L3, while the left side demonstrated longer TVPs overall. There were no statistical differences in TVP length within the LSTV cohort when comparing all levels (P > 0.05). The L3 TVPs demonstrated the longest mean lengths in both control (65%) and LSTV (58%) cohorts. The general trend was that the TVPs of L3 had the longest mean length for both the left and the right sides in both cohorts and both sexes. CONCLUSIONS: In the absence of whole-spine imaging, these findings indicate that L3 TVPs may offer an alternative bony landmark, which may aid in spinal enumeration estimation in the setting of LSTV. This is of value for radiograph appraisal and may aid with correct-level intervention.

Anatomy of mamillo-accessory foramen and prevalence of ossified mamillo-accessory ligament in lumbar vertebrae related to age.

PURPOSE: Ossification of the mamillo-accessory ligament (MAL) results in the formation of a mamillo-accessory foramen (MAF), which is associated with aging. The MAL tethers the medial branches of the lumbar dorsal rami to the lumbar vertebrae. A MAL ossified at the lumbar vertebrae can cause low back pain by compressing the medial branch of a dorsal ramus. Age ranges related to ossification of the MAL have not been reported in previous studies. The objective of the present study was to determine the prevalence of ossification of the MAL in the lumbar column and its relationship to aging, and to measure the newly formed MAF at each level of the lumbar vertebrae. METHODS: This study examined 935 dried lumbar vertebrae from 187 donors at Khon Kaen University, Thailand, consisting of 93 females and 94 males. The research focused on ossification patterns of the MAL, categorizing them into three patterns. RESULTS: We found that over 50% of ossified MAL occurred in the 30-45-year-old range and the frequency increased with age. The prevalence of ossified lumbar MAL was 72.73%, especially in L5 on the left side in females (76.92%). The width of the MAF did not differ significantly between the sexes, but it was greater on the left side (2.46 ± 1.08; n = 76) than the right (2.05 ± 0.95; n = 72) (p = 0.016). CONCLUSION: Ossification of the MAL into the MAF progresses with age, leading to low back pain from nerve compression. Physicians should be aware of the MAF during anesthesia block to treat low back pain.

Investigation of Lumbar Vertebrae and Disc Morphometry with Computed Tomography in Turkish Adults / Investigación de Vértebras Lumbares y Morfometría del Disco con Tomografía Computarizada en Adultos Turcos

SUMMARY: Conducting morphometric studies including many parameters and establishing certain standards for the anatomy of the lumbar spine will facilitate clinical applications. The Turkish example of lumbar vertebrae and disc morphometry has not yet been presented comprehensively. In our study, abdominal computed tomography images of 700 adults were evaluated retrospectively. It was observed that the anterior height of the vertebral bodies increased from L1 to L4 in males, and from L1 to L5 in females. The posterior height of the vertebral bodies was lowest at L5 in both sexes, while it was highest at L3 in males and L4 in females. In all age groups, the values for males were greater (p0.05). In all age groups and both sexes, an increase in anterior disc heights towards disc 5 was observed. The values for males were greater than those for females (p<0.05). The posterior disc height at disc 5 was higher in females, and in other discs, it was higher in males (p<0.05). In conclusion, it was found that the measurement values of the parameters examined varied according to lumbar level and sex, but were independent of age. The morphometric data we obtained are important in terms of providing a reference for the people of our region and contributing to the literature.

La realización de estudios morfométricos que incluyan diversos parámetros anatómicos y el establecimiento de ciertos estándares para la anatomía de la columna lumbar facilitarán los procedimientos clínicos. Como ejemplo, aún no se ha presentado de manera detallada la morfometría de las vértebras lumbares y del disco intervertebral en individuos turcos. En nuestro estudio evaluamos retrospectivamente imágenes de tomografía computarizada abdominal en 700 individuos adultos de ambos sexos. Observamos que la altura anterior de los cuerpos vertebrales aumentaba de L1 a L4 en los hombres y de L1 a L5 en las mujeres. La altura posterior de los cuerpos vertebrales fue más baja en L5 en ambos sexos, mientras que fue más alta en L3 en hombres y L4 en mujeres. En todos los grupos etarios los valores para los hombres fueron mayores (p0,05). En todos los grupos de edad y en ambos sexos se observó un aumento en la altura anterior del disco intervertebral hacia el disco 5. Los valores de los hombres fueron mayores que los de las mujeres (p<0,05). La altura posterior del disco intervertebral en el disco 5 fue mayor en las mujeres y en otros discos fue mayor en los hombres (p<0,05). En conclusión, se encontró que los valores de medición de los parámetros examinados variaron según el nivel lumbar y el sexo, pero fueron independientes de la edad. Los datos morfométricos que obtuvimos son importantes en términos de proporcionar una referencia para la población de nuestra región y contribuir a la literatura.

Morphological Design and Study of a 3D Printed Integrated Fusion Device Based on CT Measurement Data Assisted Anterior Lumbosacral Spine / Diseño Morfológico y Estudio de un Dispositivo de Fusión Integrado Impreso en 3D Basado en Datos de Medición de TC Asistida de Columna Lumbosacra Anterior

SUMMARY: To measure and study the anatomical morphological data of the lumbar 5 to sacral 1 intervertebral space with the aid of CT and design an anatomical anterior lumbosacral 3D printed integrated interbody fusion for the treatment of degenerative lumbosacral spine diseases. 100 adults (50 of each sex) who underwent CT examination of the lumbar spine in our hospital were selected, and their lumbar 5 to sacral 1 intervertebral space anatomical data were measured, including the anterior lumbar convexity angle, different sagittal and coronal heights, and the sagittal and coronal diameters of the superior and inferior endplates. The measured data were also statistically analyzed, and morphological design and study of the 3D printed integrated fusion device in the anterior lumbosacral spine was performed by applying computer software. When comparing the coronal and sagittal diameters of the superior and inferior endplates from lumbar 5 to sacral 1, the differences were statistically greater in men than in women (P0.001). When comparing the height at different positions in the median sagittal plane, both males and females showed an anterior high and posterior low pattern. In the coronal plane, both males and females showed the highest height in the middle position (P0.001). CT can measure the anatomical data of the lumbosacral spinal hiatus more accurately. The 3D-printed anterior integrated fusion device of the lumbosacral spine designed according to the analysis of the data results is more in line with the anatomical structure of the lumbosacral spine, fits well with the superior and inferior endplates, and effectively restores the height and anterior convexity angle of the lumbosacral space.

El objetivo de este trabajo fue medir y estudiar los datos morfológicos anatómicos del espacio intervertebral lumbar 5 a sacro 1 con la ayuda de TC y diseñar una fusión intersomática integrada anatómica lumbosacra anterior impresa en 3D para el tratamiento de enfermedades degenerativas de la columna lumbosacra. Se seleccionaron en nuestro hospital 100 adultos (50 de cada sexo) que se sometieron a un examen de TC de la columna lumbar y se midieron los datos anatómicos del espacio intervertebral lumbar 5 al sacro 1, incluyendo el ángulo de la convexidad lumbar anterior, diferentes alturas sagital y coronal, y los diámetros sagital y coronal de las placas terminales superior e inferior. Los datos medidos también se analizaron estadísticamente y se realizó el diseño morfológico y el estudio del dispositivo de fusión integrado impreso en 3D en la columna lumbosacra anterior mediante la aplicación de software informático. Al comparar los diámetros coronal y sagital de las placas terminales superior e inferior desde lumbar 5 hasta sacro 1, las diferencias fueron estadísticamente mayores en hombres que en mujeres (P 0,001). Al comparar la altura en diferentes posiciones en el plano mediano, tanto hombres como mujeres mostraron un patrón anterior alto y posterior bajo. En el plano coronal, tanto hombres como mujeres mostraron la altura más alta en la posición media (P0,001). La TC puede medir los datos anatómicos del hiato espinal lumbosacro con mayor precisión. El dispositivo de fusión anterior integrado impreso en 3D de la columna lumbosacra diseñado de acuerdo con el análisis de los resultados de los datos está más en línea con la estructura anatómica de la columna lumbosacra, se adapta bien a las placas terminales superior e inferior y restaura eficazmente la altura y la parte anterior del ángulo de convexidad del espacio lumbosacro.

Dataset of Finite Element Models of Normal and Deformed Thoracolumbar Spine.

Adult spine deformity (ASD) is prevalent and leads to a sagittal misalignment in the vertebral column. Computational methods, including Finite Element (FE) Models, have emerged as valuable tools for investigating the causes and treatment of ASD through biomechanical simulations. However, the process of generating personalised FE models is often complex and time-consuming. To address this challenge, we present a dataset of FE models with diverse spine morphologies that statistically represent real geometries from a cohort of patients. These models are generated using EOS images, which are utilized to reconstruct 3D surface spine models. Subsequently, a Statistical Shape Model (SSM) is constructed, enabling the adaptation of a FE hexahedral mesh template for both the bone and soft tissues of the spine through mesh morphing. The SSM deformation fields facilitate the personalization of the mean hexahedral FE model based on sagittal balance measurements. Ultimately, this new hexahedral SSM tool offers a means to generate a virtual cohort of 16807 thoracolumbar FE spine models, which are openly shared in a public repository.

The association between variations in the number of thoracic and lumbar vertebrae and rib morphology in adolescent idiopathic scoliosis.

PURPOSE: Preoperative counting of thoracic and lumbar vertebrae is crucial in adolescent idiopathic scoliosis (AIS) due to reported anatomical variations and potential surgical site misidentification. This study investigated characteristics associated with the vertebral number variations AIS, particularly focusing on rib morphology. METHODS: Based on three-dimensional computed tomography, patients were categorized into the non-variant number group, comprising individuals with 12 thoracic and 5 lumbar vertebrae, and the variant number group, comprising individuals with different numbers of vertebrae. Additionally, the most caudal rib morphology was classified as normal, unilateral, or hypoplastic. RESULTS: A total of 359 patients were included in our study (41 males, 318 females, age: 16.3 ± 3.1 years), with 44 patients (12.3%) assigned to the variant number group. Logistic regression analysis identified unilateral ribs (odds ratio [OR]: 10.50) and lumbosacral transitional vertebrae (LSTV) (OR 6.49) as significant risk factors associated with variations. Further analysis revealed hypoplastic ribs as a significant risk factor associated with LSTV (OR: 4.58). 8 CONCLUSION: Our study suggests that abnormal rib morphology may be associated with vertebral number variations. Close attention to rib morphology is, therefore, warranted in cases with atypical vertebral numbers. Accordingly, to ensure surgical safety and accuracy, spine surgeons must communicate these variations to the surgical team, standardize nomenclature for describing them, and intraoperatively verify fusion levels with them.

Imaging anatomy study related to unilateral biportal endoscopic lumbar spine surgery.

PURPOSE: To provide lumbar spine anatomical parameters relevant to the UBE technique and explore their intraoperative application. METHODS: CT imaging data processed by Mimics for parametric measurements, including laminar abduction angle (LAA), laminar slope angle (LSA), minimum laminar height (MLH), distance between the inferior margin of the lamina and attachment of the ligamentum flavum onto the cephalad lamina (DLL), distance between the initial point and the middle of the articular process (DIA), and distance from the inferior margin of the lamina to the inferior border of the vertebral body (DLV), and were manually measured. RESULTS: LAA and DIA gradually increase from L1 to L5. At L1, the DIA is approximately the length of 2 drill bits with a diameter of 3 mm (male: 7.77 ± 1.39 mm, female: 7.22 ± 1.09 mm), while at L5, it can reach the length of 4-5 drill bits (male: 14.96 ± 2.24 mm, female: 13.67 ± 2.33 mm). MLH, DLL, and DLV reach their maximum values at the L3 and decrease toward the cranial and caudal ends. The DLL is smallest at L5 (male: 9.58 ± 1.90 mm, female: 9.38 ± 2.14 mm), equivalent to the length of 3 drill bits, while the DLL at L3 is the length of 4-5 drill bits (male: 14.17 ± 2.13 mm, female: 14.01 ± 2.07 mm). CONCLUSION: Referring to the drill diameter during surgery can mark the extent of laminotomy. The characteristics of vertebral plate angles at different lumbar levels can provide references for preoperative incision design.

Differences in vertebral bone density between African apes.

OBJECTIVES: Low-energy vertebral fractures are a common health concern, especially in elderly people. Interestingly, African apes do not seem to experience as many vertebral fractures and the low-energy ones are even rarer. One potential explanation for this difference is the lower bone density in humans. Yet, only limited research has been done on the vertebral bone density of the great apes and these have mainly included only single vertebrae. Hence the study aim is to expand our understanding of the vertebral microstructure of African apes in multiple spinal segments. MATERIALS: Bone density in the vertebral body of C7, T12, and L3 was measured from 32 Pan troglodytes and 26 Gorilla gorilla using peripheral quantitative computed tomography (pQCT). RESULTS: There was a clear difference between the three individual vertebrae and consequently the spinal segments in terms of trabecular density and cortical density and thickness. The variation of these bone parameters between the vertebrae differed between the apes but was also different from those reported for humans. The chimpanzees were observed to have overall higher trabecular density, but gorillas had higher cortical density and thickness. Cortical thickness had a relatively strong association with the vertebral size. DISCUSSION: Despite the similarity in locomotion and posture, the results show slight differences in the bone parameters and their variation between spinal segments in African apes. This variation also differs from humans and appears to indicate a complex influence of locomotion, posture, and body size on the different spinal segments.

The Sima de los Huesos thorax and lumbar spine: Selected traits and state-of-the-art.

Information on the evolution of the thorax and lumbar spine in the genus Homo is hampered by a limited fossil record due to the inherent fragility of vertebrae and ribs. Neandertals show significant metric and morphological differences in these two anatomical regions, when compared to Homo sapiens. Thus, the important fossil record from the Middle Pleistocene site of Sima de los Huesos (SH) not only offers important information on the evolution of these anatomical regions within the Neandertal lineage but also provides important clues to understand the evolution of these regions at the genus level. We present the current knowledge of the costal skeleton, and the thoracic and lumbar spine anatomy of the hominins found in Sima de los Huesos compared to that of Neandertals and modern humans. The current SH fossil record comprises 738 vertebral specimens representing a minimum of 70 cervical, 95 thoracic and 47 lumbar vertebrae, 652 rib fragments representing a minimum of 118 ribs, and 26 sternal fragments representing 4 sterna. The SH hominins exhibit a morphological pattern in their thorax and lumbar spine more similar to that of Neandertals than to that of H. sapiens, which is consistent with the phylogenetic position of these hominins. However, there are some differences between the SH hominins and Neandertals in these anatomical regions, primarily in the orientation of the lumbar transverse processes and in the robusticity of the second ribs. The presence of some but not all of the suite of Neandertal-derived features is consistent with the pattern found in the cranium and other postcranial regions of this population.

Assessment of a fully-parametric thoraco-lumbar spine model generator with articulated ribcage.

The present paper describes a novel user-friendly fully-parametric thoraco-lumbar spine CAD model generator including the ribcage, based on 22 independent parameters (1 posterior vertebral body height per vertebra + 4 sagittal alignment parameters, namely pelvic incidence, sacral slope, L1-L5 lumbar lordosis, and T1-T12 thoracic kyphosis). Reliable third-order polynomial regression equations were implemented in Solidworks to analytically calculate 56 morphological dependent parameters and to automatically generate the spine CAD model based on primitive geometrical features. A standard spine CAD model, representing the case-study of an average healthy adult, was then created and positively assessed in terms of spinal anatomy, ribcage morphology, and sagittal profile. The immediate translation from CAD to FEM for relevant biomechanical analyses was successfully demonstrated, first, importing the CAD model into Abaqus, and then, iteratively calibrating the constitutive parameters of one lumbar and three thoracic FSUs, with particular interest on the hyperelastic material properties of the IVD, and the spinal and costo-vertebral ligaments. The credibility of the resulting lumbo-sacral and thoracic spine FEM with/without ribcage were assessed and validated throughout comparison with extensive in vitro and in vivo data both in terms of kinematics (range of motion) and dynamics (intradiscal pressure) either collected under pure bending moments and complex loading conditions (bending moments + axial compressive force).

Anatomical Analysis of the S1 Neural Foramen Using Three-Dimensional Computed Tomography Imaging: Insights for Effective S1 Nerve Root Block.

OBJECTIVE: The first sacral nerve root block (S1 NRB) is used to diagnose and treat lumbosacral and radicular pain. This study aims to clarify the anatomy of the S1 neural foramen using three-dimensional (3D) computed tomography (CT) images and to establish the optimal fluoroscopic angle, localize the S1 neural foramen on fluoroscopy, and determine the safe puncture depth for S1 NRB. METHODS: In this single-center cohort study, 200 patients with lumbar degenerative disease who underwent preoperative CT were enrolled. Four distinct studies were conducted using the CT data. Study 1 examined the correlation of the sacral slope angle and the supine and prone positions. Study 2 analyzed the tunnel view angle (TVA) using 3D reconstruction. Study 3 ascertained the location of the S1 neural foramen in fluoroscopy images. Study 4 investigated the safe depth for performing S1 NRB. RESULTS: The regression analysis in Study 1 revealed a correlation of the sacral slope angle and the supine and prone positions. Study 2 determined an optimal fluoroscopic TVA of approximately 30° for the S1 NRB. Study 3 found that the S1 neural foramen was located caudal to the L5 pedicle 1.7 ± 0.2 times the distance between the L4 and L5 pedicles. Study 4 revealed that the depths of the S1 neural foramen and root were 27.0 ± 2.1 mm and 16.5 ± 2.0 mm, respectively. CONCLUSIONS: Our study suggests an optimal fluoroscopic angle, a simple method to locate the S1 neural foramen on fluoroscopy, and an ideal puncture depth for a safe and effective S1 NRB.