Anatomy of deer spine and its comparison to the human spine

The anatomical parameters of the thoracic and lumbar regions of the deer spine were evaluated and compared with the existing data of the human spine. The objective was to create a database for the anatomical parameters of the deer spine, with a view to establish deer spine as a valid model for human spine biomechanical experiments in vitro. To date, the literature has supported the use of both calf and sheep spines as a suitable model for human spine experiments as the difficulty in procuring the human cadaveric spines is well appreciated. With the advent of Bovine Spongiform Encephalopathy (BSE) and its likely transmission to human in form of new variant Creutzfeld Jakob disease (CJD), there is a slight risk of transmission to humans through food chain if proper precautions for disposal of specimen are not adhered to. There is also a significant risk of transmission through direct inoculation to the researchers (Wells et al. Vet. Rec., 1998:142:103-106), working with infected bovine and sheep spine. The deer spines are readily available and there are no reported cases of deer being carriers of prion diseases (Ministry of Agriculture, Fisheries and Food, 1998). Six complete deer spines were measured to determine 22 dimensions from the vertebral bodies, endplates, disc, pedicles, spinal canal, transverse and spinous processes, articular facets. This was compared with the existing data of the human spine in the literature. The deer and human vertebrae show many similarities in the lower thoracic and upper lumbar spine, although they show substantial differences in certain dimensions. The cervical spine was markedly different in comparison. The deer spine may represent a suitable model for human experiments related to gross anatomy of the thoracic and lumbar spine. A thorough database has been provided for deciding the validity of deer spine as a model for the human spine biomechanical in vitro experiments.     

A morphometric study of the lumbar spinous process in the Chinese population

Our goal was to analyze the anatomical parameters of the lumbar spine spinous process for an interspinous stabilization device designed for the Chinese population and to offer an anatomical basis for its clinical application. The posterior lumbar spines (T₁₂-S₁) of 52 adult cadavers were used for measuring the following: distance between two adjacent spinous processes (DB), distance across two adjacent spinous processes (DA), thickness of the central spinous processes (TC), thickness of the superior margin of the spinous processes (TS), thickness of the inferior margin of the spinous processes (TI), and height of the spinous processes (H). Variance and correlation analyses were conducted for these data, and the data met the normal distribution and homogeneity of variance. DB decreased gradually from L_1-2 to L₅-S₁. DA increased from T₁₂-L₁ to L_2-3 and then decreased from L_2-3 to L_4-5. The largest H in males was noted at L₃ (25.45±5.96 mm), whereas for females the largest H was noted at L₄ (18.71±4.50 mm). Usually, TS of the adjacent spinous process was lower than TI. Based on the anatomical parameters of the lumbar spinous processes obtained in this study, an “H”-shaped coronal plane (posterior view) was proposed as an interspinous stabilization device for the Chinese population. This study reports morphometric data of the lumbar spinous processes in the Chinese population, which provides an anatomical basis for future clinical applications.     

Comparative and functional anatomy of the mammalian lumbar spine

As an essential organ of both weight bearing and locomotion, the spine is subject to the conflict of providing maximal stability while maintaining crucial mobility, in addition to maintaining the integrity of the neural structures. Comparative morphological adaptation of the lumbar spine of mammals, especially in respect to locomotion, has however received only limited scientific attention. Specialised features of the human lumbar spine, have therefore not been adequately highlighted through comparative anatomy. Mathematical averages were determined of 14 measurements taken on each lumbar vertebrae of ten mammalian species (human, chimpanzee, orang-utan, kangaroo, dolphin, seal, Przewalski's horse, cheetah, lama, ibex). The revealed traits are analysed with respect to the differing spinal loading patterns. All examined mammalian lumbar spines suggest an exact accommodation to specific biomechanical demands. The lumbar spine has reacted to flexion in a predominant plane with narrowing of the vertebral bodies in quadrupeds. Torsion of the lumbar spine is withstood by an increase in the transverse distance between the inferior articular processes in the upper lumbar spine in primates, but lower lumbar spine in humans, quadrupeds and the seal. Sagittal zygapophyseal joint areas resist torsion in the seal and humans. Ventral shear is resisted by frontal zygapophyseal joint areas in humans and primates, and dorsal shear by encompassing joints in the ibex. The human fifth lumbar vertebra is remarkable in possessing the largest endplate surface area and the widest distance between the inferior articular processes, as an indicator of the high degree of axial load and torsion in bipedalism.     

New Method for Predicting the Lumbar Lordosis Angle in Skeletal Material

Reconstructing the lordotic curvature of the lumbar spine in humans is essential for understanding their posture and locomotion. To date there is still no reliable method for predicting the lordotic curvature of disarticulated spines (in the absence of intervertebral disks). This article examines two possible methods for predicting the lordotic curvature of the lumbar spine. The first—the traditional method—is based on the degree of wedging of the vertebral bodies, and the second—the suggested new method—is based on a lateral view of the orientation of the inferior articular processes. We propose a linear regression model for predicting the lordotic curvature of the lumbar spine (lordosis angle) in disarticulated human spines. This model, derived directly from our new method, is a more reliable predictor of the lumbar lordosis angle in disarticulated spines. Anat Rec, 2007. © 2007 Wiley‐Liss, Inc.     

Establishing intercrestal line by posture:--a radiographic evaluation

In this study, we examined the position of intercrestal line that is called Jacoby's line at heights of the vertebral body and spinous process in different positions of the lumbar spine using radiographs of 100 subjects. At the height of the spinous process, Jacoby's line was most often observed in the extension position in L4 spinous process middle 1/3 region in males and in L4-5 interspinous region in females. In the neutral position, it was in L4 spinous process middle 1/3 region in males and in L4-5 interspinous region in females. And that in the flexion position, it was in L4-5 interspinous region in both males and females. At the height of the vertebral body, Jacoby's line was most often observed in the extension position in L4-5 intervertebral region in males and in L5 vertebral body upper 1/3 region in females. In the neutral position, it was in L4 vertebral body lower 1/3 region in males and in L5 vertebral body upper 1/3 region in females. In the flexion position, it was in L5 vertebral body upper 1/3 region in males and in L5 vertebral body upper 1/3 region or L4 vertebral body lower 1/3 region in females. There was no gender difference in the most often observed position of Jacoby's line at the height of the spinous process in the flexion position. The position of Jacoby's line was found to vary in different positions of the lumbar spine. Positioning Jacoby's line in the neutral lumbar spine from the body surface, as conventionally proposed, was not always accurate, and it was considered practical to establish Jacoby's line using the spinous process in the flexion of the lumbar spine as the standard. When Jacoby's line is established by this method, it is considered to be positioned between L4-5 spinous processes middle 1/3 regions. In subarachnoid puncture in elderly patients, the puncture may be performed at a higher position in relation to the spinal cord because of spinal degeneration. Therefore, it is important to perform subarachnoid puncture in elderly patients at a site lower than the established Jacoby's line.     

人体中、下段颈椎曲率的测量及意义

目的：为设计、改进适合国人的颈前路钢板系统提供参考值。方法：用游标卡尺和自制弧度仪测量129例颈椎各椎体最小高度、冠状径、矢状径和前壁横向弧度;测量43例正常成人X线侧位片,计算颈椎的生理曲度。结果：C3-C6最小高度和C3-C5最小矢状径均较接近,分别为10.0mm和14.6mm;最小冠状径由C3-C6依次增加,增量约1mm;椎体前壁横向曲率半径由C3的9.6mm逐渐增大至C7的14.4mm;颈椎各节段纵向曲度的变异较大,无明显规律。结论：颈椎中段各椎体的最小高度值、矢状径值相近,中、下段颈椎各椎体的最小冠状径和前壁横向曲度由下至下递减,此规律可帮助确定理想的螺钉长度、钢板宽度和钢板的横向弧度;颈椎纵向生理曲度变异较大,无明显规律性,对确定钢板的纵向弧度帮助不大。     

不同国家人群胸椎椎弓根解剖结构的对比研究

目的　通过文献回顾对比不同国家人群胸椎椎弓根解剖结构的异同,为胸椎手术中椎弓根钉的选择、手术成功率及安全性的提高奠定理论基础。 方法　以 “胸椎”、“椎弓根”、“解剖”、“测量”等为关键词,语言限定为英语或中文,在中国知识网、Pubmed、Web of knowledge等数据库中检索相关文献。排除不符合要求的文献,根据实验对象来源地将纳入文献进行国别划分,对比不同国家人群胸椎椎弓根解剖参数的异同。 结果　共20篇文献被纳入对比性研究。椎弓根高（pedicle height, PDH）最小值均位于T1,最大值位于T11或T12,中间椎序列PDH变化相对较小;不同国家人群椎弓根宽（pedicle width,PDW）均随椎序数的增加呈现先减小后增大的变化趋势,最小值位于T4或T5;虽然来自不同国家人群椎弓根水平面夹角（transverse pedicle angle,TPDA）数值存在一定差异,但均自T1~T10随椎序的增加呈减小趋势。 结论　不同国家人群胸椎椎弓根解剖参数随椎序变化呈现大致相同的变化趋势,但其具体解剖参数尚存在一定差异,熟悉上述解剖差异是提高手术成功率与安全性的关键。     

Prediction of the human thoracic and lumbar articular facet joint morphometry from radiographic images

The articular facet joints (AFJ) play an important role in the biomechanics of the spine. Although it is well known that some AFJ dimensions (e.g. facet height/width or facet angles) play a major role in spinal deformities such as scoliosis, little is known about statistical correlations between these dimensions and the size of the vertebral bodies. Such relations could allow patient-specific prediction of AFJ morphometry from a few dimensions measurable by X-ray. This would be of clinical interest and could also provide parameters for mathematical modeling of the spine. Our purpose in this study was to generate prediction equations for 20 parameters of the human thoracic and lumbar AFJ from T1 to L4 as a function of only one given parameter, the vertebral body height posterior (VBHP). Linear and nonlinear regression analyses were performed with published anatomical data, including linear and angular dimensions of the AFJ and vertebral body heights, to find the best functions to describe the correlations between these parameters. Third-order polynomial regressions, in contrast to the linear, exponential and logarithmic regressions, provided moderate to high correlations between the AFJ parameters and vertebral body heights; e.g. facet height superior and interfacet width (R2, 0.605-0.880); facet height inferior, interfacet height and sagittal/transverse angle superior (R2, 0.875-0.973). Different correlations were found for facet width and transverse angle inferior in the thoracic (R2, 0.703-0.930) and lumbar (R2, 0.457-0.892) regions. A set of 20 prediction equations for AFJ parameters was generated (P-values < 0.005, anova). Comparison of the AFJ predictions with experimental data indicated mean percent errors <13%, with the exception of the thoracolumbar junction (T12-L1). It was possible to establish useful predictions for human thoracic and lumbar AFJ dimensions based on the size of the vertebral bodies. The generated set of equations allows the prediction of 20 AFJ parameters per vertebral level from the measurement of the parameter VBHP, which is easily performed on lateral X-rays. As the vertebral body height is unique for each person and vertebral level, the predicted AFJ parameters are also specific to an individual. This approach could be used for parameterized patient-specific modeling of the spine to explore the clinically important mechanical roles of the articular facets in pathological conditions, such as scoliosis.     

腰椎棘突间区的影像解剖学研究及其临床意义

目的：探讨三维CT重建腰椎棘突间区的方法及其临床意义。方法：GE light speed 16 pro螺旋CT扫描患者46人，扫描条件为层厚0．625mm，层距0．3mm，在图像工作站中ADW4．2软件采用容积再现及多平面重建技术重建T12至S1段脊柱三维图像，对图像进行整倍数放大，并使用图像工作站（Advantage Workstation）软件中的测量工具，对棘突间距，棘突顶距，棘突中央高度，相邻棘突上下缘及中央厚度进行测量，测量过程中可以对腰椎三维图像任意角度旋转，选择最佳测量图像，对测量的图像数据进行正态性检验、t检验。结果：腰椎棘突间距从上到下（L1～5）逐渐减小，L1～2为8．26mm，L4～5，为5．66mm。棘突顶距棘突中央高度中段大于上段和下段，T12～L1的棘突顶距为54．91mm，至L2～3，增大为59．35mm，L4～5减小为47．13mm。L3的棘突高度最大，为21．56mm，上一棘突下缘大于相邻下一棘突上缘厚度。女性棘突较男性棘突短薄矮（P〈0．05～P〈0．01）。结论：本研究可模拟生理状态下腰椎棘突间区解剖，所测指标呈正态分布，能够反映国人腰椎棘突间区解剖，为腰椎棘突间内固定器的设计和临床的应用及计算机导航手术系统的应用提供解剖学基础。     

Morphometric analysis of the relationships between intervertebral disc and vertebral body heights: an anatomical and radiographic study of the human thoracic spine

The main aim of this study was to provide anatomical data on the heights of the human intervertebral discs for all levels of the thoracic spine by direct and radiographic measurements. Additionally, the heights of the neighboring vertebral bodies were measured, and the prediction of the disc heights based only on the size of the vertebral bodies was investigated. The anterior (ADH), middle (MDH) and posterior heights (PDH) of the discs were measured directly and on radiographs of 72 spine segments from 30 donors (age 57.43 ± 11.27 years). The radiographic measurement error and the reliability of the measurements were calculated. Linear and non-linear regression analyses were employed for investigation of statistical correlations between the heights of the thoracic disc and vertebrae. Radiographic measurements displayed lower repeatability and were shorter than the anatomical ones (approximately 9% for ADH and 37% for PDH). The thickness of the discs varied from 4.5 to 7.2 mm, with the MDH approximately 22.7% greater. The disc heights showed good correlations with the vertebral body heights (R(2), 0.659-0.835, P-values < 0.005; anova), allowing the generation of 10 prediction equations. New data on thoracic disc morphometry were provided in this study. The generated set of regression equations could be used to predict thoracic disc heights from radiographic measurement of the vertebral body height posterior. For the creation of parameterized models of the human thoracic discs, the use of the prediction equations could eliminate the need for direct measurement on intervertebral discs. Moreover, the error produced by radiographic measurements could be reduced at least for the PDH.     

A semi-automated method using interpolation and optimisation for the 3D reconstruction of the spine from bi-planar radiography: a precision and accuracy study

The 3D reconstruction of the spine in upright posture can be obtained by bi-planar radiographic methods, developed since the 1970s. The principle is to identify 4–25 anatomical landmarks per vertebrae and per images. This identification time is hardly manageable in clinical practice. A semi-automated method is used: 3D standard vertebral models are positioned along with a 3D curve (identified all the way through the vertebral bodies). The silhouettes of the models of C7 and L5 vertebrae are first adjusted and the positions of the other vertebrae are interpolated and optimised. The inter- and intra-operator variabilities and the errors between the semi-automated method and the manual identification of six anatomical landmarks per vertebra are evaluated on 20 pairs of X-ray images of subjects with different spinal deformities. The identification time for the semi-automated method is 5 min. For scolitic subjects, the precision is under 2.2° and the accuracy is under 3.2° for all lateral, sagittal and axial rotations.     

颈椎拔伸旋转手法内在应力的实时监测

目的研究颈椎拔伸旋转手法内在应力的分布特点。方法应用有限元分析软件在颈椎CT片基础上逐步重建C3/4～C6/7颈椎模型并网格化。将颈椎拔伸旋转手法分解后的各项力学参数代入模型进行计算分析,即时显示手法作用时模型内在应力的变化。结果拔伸过程,模型应力集中的区域及大小呈由大减少再增大的趋势,应力主要在C3/4关节突关节;拇指向左推C4棘突过程中,C4棘突的左下部、根部、棘突左侧根部与椎弓根结合处先后出现应力集中,最大应力为9.627kPa;颈椎向右旋转40°的过程中,C3～6双侧关节突关节,C4～6的椎弓、棘突根部、二者结合处及椎体侧方等都先后出现应力集中,右侧C3/4关节突关节应力最大,为363.6kPa。颈椎快速返回中立位,模型应力集中的区域及大小均快速减少。结论颈椎拔伸旋转手法下的颈椎有其独特的应力变化规律。关节突关节在颈椎活动中承受主要应力。右旋40°时模型所受压力最大,但不会损伤正常颈椎骨性结构。     

腰椎棘突、椎板及下关节突的影像解剖

目的：测量国人腰椎4、5（L4、L5）棘突、椎板及下关节突相关解剖学结构,为设计最优化的椎弓根螺钉- 翼状曲面钢板系统提供数据基础,为下一步临床试验奠定基础。方法：选取长征医院患者的脊柱三维CT影像学资 料,并将其通过3D打印技术建立模型,采用不同影像学测量方法及在3D模型上进行实物测量的方法,获得L4、L5 棘突厚度、棘突侧面大小、下关节突厚度、椎板与棘突成角、下关节突与椎板成角、下关节突与棘突成角、棘突 根部至上关节突根部的距离等数据。结果：男、女性测量结果差异没有统计学意义。以男性为例,L4的棘突边距、 棘突中央高度分别为（24.55±2.31）mm、（23.06±2.89）mm,L5的棘突边距和棘突中央高度则分别为（20.87± 2.61）mm、（21.52±3.08）mm,两椎体的棘突厚度均呈从上至下增厚的趋势。在L4,棘突根部至上关节突根部距 离、棘突侧面与下关节突面夹角、下关节突面与椎板面夹角（A2）、下关节突面中心处矢状线方向厚度和下关节突 面中心处垂直于下关节突面方向的厚度分别为（10.33±1.03）mm、（149.74±6.40） °、（140.53±12.33） °、（10.51± 0.53）mm、（10.98±0.65）mm ;在L5,由于3D打印模型的L4、L5为一个整体,影响了A2的测量,其他指标分别 为（16.42±1.66）mm、（146.47±7.90） °、（11.38±0.86）mm、（10.15±0.62）mm。结论：国人脊柱L4、L5椎板、 棘突及上、下关节突的解剖学数据可为腰椎峡部翼状曲面钢板的设计研发提供精确参考。     

Comparing the anatomical consistency of the posterior superior iliac spine to the iliac crest as reference landmarks for the lumbopelvic spine: a retrospective radiological study

A palpation reference line coursing between the superior-most aspect of the iliac crests has been reported to cross the L4 spinous process or L4/L5 intervertebral space in approximately 80% of the population. Comparable data have not been defined for the line coursing between the posterior superior iliac spines (PSIS). The purpose of this study was to compare the anatomical consistency of the PSIS to the iliac crest as landmarks used for spinal palpation. One hundred computerized tomographic images were reviewed in a three-dimensional setting. Two horizontal lines were constructed on each image: Line 1 representing the superior-most aspect of the iliac crest and Line 2 representing the inferior margin of the PSIS. The vertical distance between each horizontal line and the inferior edge of its respective spinous process were measured. The PSIS corresponded to the S2 spinous process in 81% of subjects and the iliac crest to the L4 spinous process in 59% of subjects. Distance measures suggest that the PSIS was closer to S2 versus the iliac crest to L4 (t = 6.998; P < 0.01). The PSIS crossed S2 more frequently than the iliac crest crossed L4 (chi(2) = 12.719, P < or = 0.01). The study findings support the relationship between the PSIS, and the spinous process of S2 is more consistent when compared to the iliac crest and the spinous process of L4. The PSIS reference line may be used to find S2 as a reference standard in validity and reliability palpation studies in the lower lumbar spine.     

Influence of anteroposterior shifting of trunk mass centroid on vibrational configuration of human spine

This study attempts to determine the influence of anteroposterior (A-P) shifting of trunk mass from the upright sedentary posture on dynamic characteristics of the human lumbar spine. A three-dimensional finite element (FE) model comprising of the T12-Pelvis spine unit was used to mimic the human spine system. It is not clear how the A-P shifting of the upper part of human upper body affect on vibrational modality of the human lumbar spine under whole body vibration. Five trunk mass point locations were assumed by 2.0cm anterior, 1.0cm anterior, 1.0cm posterior and 2.0cm posterior to the upright sedentary posture including no shifting posture. FE modal analysis was used to extract the resonant frequencies and vibration modes of the human spine. The analytical results indicate that trunk mass centroid shifting onwards or rearwards may result in a reduction of vertical resonant frequency of the human spine. The human spine has the highest vertical resonant frequency at the normal upright sedentary posture with the trunk mass locating around 1.0cm anterior to the L3-L4 vertebral centroid. Larger A-P deformations and rotational deformations were also found at the spine motion segments L3-L4 and L4-L5, which imply higher compressive stress and shear stress at the disc annulus of those spinal motion segments. The findings in this study may explain why long-term whole body vibration might induce the degeneration of human spine at the relevant spinal motion segments.     

Evaluation of effectiveness of a facet wiring technique: Anin vitro biomechanical investigation

The effects of facet wiring procedure commonly used for stabilizing cervical spines after laminectomy or bilateral facet dislocation on the motion behavior of whole cervical spines are investigated using a Selspot II^® system. A fresh human ligamentous intact specimen was potted at T1/T2 vertebra and clinically relevant loads applied to the topmost vertebra (C2) of the specimen. The resulting three rotational components of each of the five vertebral bodies (C3-C7) were recorded. Specimen was injured to mimic total laminectomies at C5 and C6 vertebral levels and tested again. The injured specimen was stabilized, using a facet wiring construct, across C4-C7 segment before testing for the final time. The injured specimens, compared to the intact specimens, demonstrated an increase in flexion-extension of about 10%. Facet wiring imparted stability to the cervical spine by stiffening segments up to roughly four times intact values.