下腰椎神经根管容积测量的实验研究

目的　探讨下腰椎神经根管骨性容积的评价方法 ,为神经根管提供一种定量测量指标。方法福尔马林浸泡尸体标本 2 0具 ,先后采用螺旋CT(SCT)扫描及灌腊法测量L3 ,4、L4,5、L5S1左、右侧神经根管容积。SCT扫描范围自L3 上缘至S2上缘 ,利用O2图像工作站将原始扫描图像进行 3D重建 ,分别以上、下椎弓根中点及内、外缘所围成的区域作为神经根管的容积 ,并与灌腊法直接测量神经根管容积进行比较。结果两种测量方法比较无显著性差异 (P >0 .0 5 )。结论利用螺旋CT三维重建方法重建下腰椎神经根管骨性容积简便、易行、可靠 ,可为临床神经根管源性疾病诊断提供定量指标 ;容积评估更能反映神经根管真实变化 ;以上、下椎弓根中点及内、外缘所围成的区域作为神经根管的容积评估标准 ,人为操作误差明显减少 ,且与椎间盘、神经根管变化密切相关。     

螺旋CT三维重建诊断腰椎爆裂骨折的价值

目的探讨螺旋CT多模式三维重建诊断腰椎爆裂骨折(LBF)的价值。方法对54例LBF患者摄腰椎X线片;采用3～5 mm层厚连续螺旋CT扫描,1.5～2.5 mm间距后重建,于AW4.0工作站行SSD、MPR及MIP、仿真椎间盘镜(VMED)三维重建;34例行腰椎MRI检查;采用SSPS 16.0软件分析。结果螺旋CT与平片诊断LBF差异有统计学意义(χ2=4.167,P<0.05);SSD与MIP能取得清晰立体图,MPR能多向观察骨折细节,VMED能模拟MED显示椎管梗阻。MRI能清楚显示椎管受压及脊髓损伤。结论腰椎多模式三维重建对复杂性腰椎骨折诊断、分型与手术模拟等有重要价值。     

基于腰椎螺旋CT图像以卷积神经网络技术全自动识别并重建椎间盘的可行性

目的观察基于腰椎螺旋CT图像以卷积神经网络技术全自动识别及重建椎间盘的可行性。方法回顾性分析400例腰痛患者的腰椎CT资料,以其中320例为训练集、40例为验证集、40例为测试集。以人工智能(AI)系统进行学习训练和测试。以深度学习(DL)卷积神经网络3D V-Net技术分割腰椎轴位CT图像中的椎体与椎间盘,并轴位重建椎间盘;以Dice系数评估分割精度。由2名放射科医师分别对AI重建图像及人工重建图像进行图像质量评分并进行对比。结果AI分割骶椎椎体、L5椎体、L1~L4椎体及椎间盘的Dice系数分别为0.953、0.940、0.940及0.926,平均为0.940。针对测试集40例,采用腰椎螺旋CT数据经卷积神经网络技术完成197个椎间盘重建。2名放射科医师对197幅AI重建图像及人工重建图像的中位评分均为4分,差异无统计学意义(P均>0.05);评分一致性加权Kappa值为0.862[95%CI(0.778,0.946),P<0.001]。结论基于腰椎螺旋CT图像卷积神经网络全自动识别及重建椎间盘的可行性令人满意。     

多层螺旋CT三维重建影像在面部轮廓改型中的应用

目的 探讨多层螺旋CT三维重建影像在面部轮廓改型中的临床应用价值。方法 对25例面部轮廓形态异常者行多层螺旋CT头颅扫描，层厚1．0～2．0mm，应用表面投影显示法（SSD）重建三维图像，从不同旋转轴对不同改型部位的三维图像进行观察。兴趣区还可应用勾画删除技术。对图像进行切割删除处理，以便获得单独显示兴趣区的图像。结果 螺旋CT三维重建能清楚显示面部轮廓复杂的立体解剖结构，尤其是与毗邻结构的关系。所得重建图像逼真。可任意剖面和多视觉变换，显示颅面各结构的空间位置关系和定量测量分析。结论 三维CT重建技术为面部轮廓改型的手术设计与实施，提供了新的可靠手段。     

多层螺旋CT图像后处理技术对腰椎峡部裂的诊断价值

目的：探讨多层螺旋CT图像后处理技术对腰椎峡部裂的诊断价值。方法：应用多层螺旋CT机对43例腰椎峡部裂患者的腰椎进行扫描，利用多平面重建（MPR）、最大密度投影（MIP）、容积显示技术（VRT）进行多模式图像后处理，多方位观察患者椎弓峡部裂情况。结果：43例患者中共发现83个椎弓峡部裂，双侧32例，其中4例累及两个脊椎的双侧椎弓；单侧11例。腰椎斜矢状位MPR及平行于椎弓的轴位MPR能够诊断全部病例，13例裂隙呈不规则锯齿状，边缘清晰，9例边缘骨质硬化、膨大；12例伴有碎骨块，并见裂隙周围纤维组织增生。正中矢状位MPR发现脊椎向前滑脱22例，其中Ⅰ度滑脱16例，Ⅱ度滑脱5例，Ⅲ度滑脱1例。7例出现假性椎间盘膨出征，硬膜囊向前移行。MIP也能全部显示所有病例的峡部裂，但是对软组织观察不如MPR。高密度VRT仅发现峡部裂23例39处。结论：多层螺旋CT扫描后MPR、MIP及VRT图像后处理技术能够全方位评价腰椎峡部裂的形态变化，为临床提供与峡部裂有关的更多更详细的影像信息，MPR是最有价值的重建方法。     

数字化技术在骨科的临床应用

目的 探讨数字骨科学理论及数字化技术在骨科中的应用. 方法 数字骨科解剖学:获取健康成人下肢连续薄层CT扫描数据,三维重建股前外侧皮瓣结构并立体显示;获取健康成人髋髓膝、踝关节连续薄层CT扫描数据,三维重建各关节后均建股骨头、膝关节、胫骨平台、踝关节中心,三维重建下肢的机械轴线.数字骨科手术设计与应用:获取12例成人单侧髋关节发育不良患者骨盆连续螺旋CT扫描数据,三维构建患侧髋关节解剖旋转中心,设计髋臼侧假体最佳置入导航模板并应用于临床,验证结果.虚拟骨科仿真:获取8例男性志愿者腰椎螺旋CT扫描数据,三维重建L4.5椎体、椎间盘及韧带,建立Wallis系统模型,按标准手术模式与腰椎模型拟合,进行有限元前处理:选取单侧先天性髋关节脱位儿童1例,模拟Pcmbc rton截骨矫形过程. 结果 重建的数字化模型可准确反映解剖学结构特点,快速成型导航模板有较好的匹配性,且操作易行、可靠;虚拟仿真可以再现手术方式及过程. 结论 重建的图像可以提供骨关节正常三维动态解剖,为“数字骨科学”概念的建立奠定了良好的基础.     

三维螺旋CT重建对下颌骨缺损修复的指导意义

目的 探讨多层螺旋CT三维重建影像在修复下颌骨缺损中的指导意义.方法 对15例下颌骨缺损患者行64排螺旋CT头颅扫描,层厚0.65 mm,应用表面投影显示法(SSD)重建三维图像,从不同旋转轴对下颌骨缺损进行三维重建,根据重建影像进行术前设计和术后效果对比观察.结果 螺旋CT三维重建能清楚显示下颌骨缺损的详尽立体解剖结构,所得重建图像逼真,可观察任意剖面和多视觉变换,显示下颌骨的空间位置关系和定量测量分析.结论 三维CT重建技术为下颌骨缺损修复的手术设计与实施,提供了新的可靠依据.     

螺旋CT测量颈椎椎体间隙准确性的验证

[目的]验证螺旋CT测量颈椎椎体间隙的准确性,为螺旋CT测量颈椎椎体间隙提供理论依据.[方法]选取8具男性(30 ～ 52岁,平均年龄37.7岁)新鲜尸体,排除先天畸形,创伤,肿瘤及明显退行性变,取其头颈部标本.在颈椎生理曲度下,螺旋CT扫描标本,三维重建图像,测量颈椎椎体间隙的前后径,左右径,正中矢状面上的前缘,中点及后缘的高度.将颈椎标本固定于相同的生理曲度.在C型臂X线机透视引导下,以外固定支架固定颈椎标本,刮除干净各间隙椎间盘和软骨终板,在间隙内灌注硅胶,待硅胶凝固后,松开外固定支架,取出硅胶模型,修剪模型边缘至光滑.应用激光三维扫描仪创作硅胶模型的三维图像.测量其各项径线.[结果]将CT扫描的测量值与硅胶模型的测量值进行配对t检验.P值范围为0.058 ～0.893,均大于0.05,CT扫描与硅胶模型的测量值不存在显著差异.[结论]螺旋CT测量颈椎椎体间隙结果准确,可以作为测量较大样本量颈椎标本的可信方法.硅胶塑形法与螺旋CT扫描法相结合,能更好地为符合国人解剖特点的仿生型颈椎椎体间融合器的研发工作提供形态学依据.     

椎体终板的凹陷角与腰椎间盘退变的相关性

目的研究下腰椎椎体终板的凹陷角以及它在腰椎间盘退变时的变化规律.方法129例研究对象依据椎间盘退变情况分成3组对照组27例,共54个椎间盘(L4,5、L5S1椎间盘各27个);腰椎间盘退变102例,共158个椎间盘(L4,5椎间盘84个,L5S1椎间盘74个),按退变程度分为2组腰椎间盘轻度退变组,共99个椎间盘(L4,5椎间盘53个,L5S1椎间盘46个);腰椎间盘重度退变组,共59个椎间盘(L4,5椎间盘31个,L5S1椎间盘28个).所有病例摄腰椎正侧位X线片及腰椎MR检查,将X线片及MR图像输入计算机.在MRI正中矢状面T2加权像上测量终板凹陷角,并观察退变椎间盘相邻椎体骨髓的MRI信号改变;在X线片上测量椎体的相对前高、后高和矢状径.结果①终板凹陷角在男女两性间差异无显著性(P＞0.05);②终板的凹陷角在对照组、腰椎间盘轻度和重度退变组逐渐增大,两两间差异有显著性(P＜0.05);③退变椎间盘的上下位椎体的相对前高、后高在对照组、腰椎间盘轻度和重度退变组逐渐减小,而相对矢状径逐渐增大,两两间比较差异均有显著性(P＜0.05);④椎间盘轻度、重度退变组的相邻椎体骨髓的MRI信号改变率分别为24%和44%,差异有显著性(P＜0.05).结论腰椎间盘退变时,病变间隙椎体终板凹陷角增大、终板倾向平坦化,其平坦化程度与退变的严重程度有关.终板的平坦化是椎间盘退变时椎体骨重建结果,可能是对椎间盘退变时生物力学变化的一种自我保护机制.     

腰椎间盘突出症患者下腰椎终板矢状面形态特征

目的:观察腰椎间盘突出症(lumbar disc herniation,LDH)患者下腰椎(L3～S1)终板矢状面形态特征。方法:回顾性分析2016年6月～2017年7月就诊我院的腰椎间盘突出症患者和无明确腰椎疾病的志愿者。共纳入LDH患者141例,其中男61例,女80例,年龄61.6±10.1岁(41～79岁),身体质量指数(BMI)为26.3±3.4(18.3～33.2)。对照组纳入志愿者109例,其中男47名,女62名,年龄55.4±12.2岁(40～87岁), BMI为25.3±3.6 (17.6～32.5)。在腰椎CT正中矢状面重建图像上测量LDH患者椎间盘突出节段的终板形态和志愿者腰椎L3下终板至S1上终板的终板形态学参数,包括终板屈曲深度(ECD)、矢状面屈曲角(SCA)和终板屈曲顶点位置(ECA);相应节段椎间盘退变程度在MRI上通过Pfirrmann分级进行评估。应用t检验比较LDH组与对照组终板矢状面形态学参数;选择L4/5和L5/S1两节段中相同退变程度(PfirrmannⅢ级,PfirrmannⅣ级)的椎间盘,比较LDH组患者和对照组志愿者的终板矢状面形态。将LDH组患者和对照组志愿者终板数据合并后按照椎间盘退变程度分组(PfirrmannⅡ级～PfirrmannⅤ级),应用Kruskal-Wallis检验比较不同退变程度椎间盘终板形态参数的组间差异。结果:LDH组各节段终板ECD均显著低于对照组(L4上终板P=0.016,其余终板P0.01),SCA均显著大于对照组(P0.01);除L3下终板外(P=0.014),所有节段终板ECA的组间差异无统计学意义(P0.05)。L4/5和L5/S1节段中PfirrmannⅢ级和Ⅳ级椎间盘终板,相同节段和退变分级的组间比较结果显示,LDH组终板ECD显著小于对照组(P0.05),SCA显著大于对照组(P0.05),ECA未出现组间显著性差异(P0.05)。不同退变程度椎间盘终板形态参数组间比较显示,随着椎间盘退变进展,各节段ECD降低(P0.01),SCA增大(P0.01),ECA未出现一致的组间变化趋势。结论:LDH患者相比对照组志愿者,其下腰椎终板矢状面屈曲程度较低,退变程度较高的椎间盘其终板屈曲程度较小。     

A morphological study of lumbar vertebral endplates: radiographic, visual and digital measurements

Purpose

Clinical observations suggest that endplate shape and size are related to complications of disc arthroplasty surgery. Yet, the morphology of the vertebral endplate has not been well defined. This study was conducted to characterize the morphology of lumbar vertebral endplates and to quantify their morphometrics using radiographic, visual and digital measures.

Methods

A total of 591 vertebral endplates from 76 lumbosacral spines of men were studied (mean age 51.3 years). The shape of the vertebral endplates was classified as concave, flat and irregular, and was evaluated from both radiographs and cadaveric samples. Each endplate was further digitized using a laser scanner to quantify diameters, surface area and concavity for the whole endplate and its components (central endplate and epiphyseal rim). The morphological characteristics and morphometrics of the vertebral endplates were depicted.

Results

In both radiographic and visual assessments, more cranial endplates (relative to the disc) were concave and more caudal endplates were flat at all disc levels (p < 0.001). On average, the mean concavity depth was 1.5 mm for the cranial endplate and 0.7 mm for the caudal endplate. From L1/2 down to L5/S1 discs, the vertebral endplate gradually changed into a more oval shape. The central endplate was approximately 70 % of the diameter of the whole endplate and the width of the epiphyseal rim varied from 3 to 7 mm.

Conclusions

There is marked morphological asymmetry between the two adjacent endplates of a lumbar intervertebral disc: the cranial endplate is more concave than the caudal endplate. The size and shape of the vertebral endplate also vary considerably between the upper and lower lumbar regions.     

不同程度退变的软骨终板的影像学变化及其临床意义

目的：从影像学角度研究腰椎间盘不同程度退变时终板在矢状面和横断面的形态变化规律，探讨其临床意义。方法：本研究选取58例L4．5椎间盘呈退行性改变的影像学资料（MRI、CT）进行研究（其中椎间盘突出者34例），分别将其矢状位MRI T2WI成像采用MRI机内Mean／Curve测量软件测量L4．5运动节段退变的椎间盘与相应节段脑脊液平均信号强度比值，判断椎间盘退变程度进行分组。分为3组：轻度退变组17例，中度退变组17例，重度退变组24例。同时采用正中矢状位MRI T2WI成像分别测量相应椎间（L4．5）终板于矢状面上的凹陷角。另外借助L4．5椎间CT平扫成像测量其相邻终板的最大前后径和横径，计算终板的相对曲率，分析椎间盘在不同退变程度下椎体终板凹陷角及其相对曲率的变化规律，并探讨椎体终板的凹陷角与其相对曲率的相关性。结果：①椎体终板（L4下终板，L5上终板）凹陷角均随着相应椎间盘退变程度加重而增大，重度退变组与中度、轻度退变组（L4下终板、L5上终板）凹陷角差异均有统计学意义（P〈0．01）。②重度退变组与轻度退变组（L4下终板、L5上终板）相对曲率差异有统计学意义（P〈0．01），中度退变组与轻度退变组（L4下终板、L5上终板）相对曲率差异有统计学意义（P〈0．01），中度退变组与重度退变组（L4下终板、k上终板）相对曲率差异无统计学意义（P〉0．05）。⑧终板凹陷角与其相对曲率呈正相关关系（r：0．786，0．490）。结论：椎体终板的凹陷角与相对曲率随着椎间盘退变程度加重而发生相应变化，这种变化是腰椎间盘退变突出、椎间盘源性下腰痛的重要因素，且椎体终板的凹陷角与其相对曲率存在着相关关系，故可以通过凹陷角的变化判断其相对曲率的改变，评估椎间盘突出的概率。     

The effects of bone density and disc degeneration on the structural property distributions in the lower lumbar vertebral endplates.

In this study, we hypothesized that vertebral bone density and disc degeneration would affect the structural property distributions of the lower lumbar vertebral endplates (L3-L5). The results may have implications for improving interbody implant designs to better resist subsidence. A 3 mm diameter hemispherical indenter was used to perform indentation tests at 0.2 mm/s to a depth of 3 mm at 27 standardized locations in 55 bony endplates of intact human lumbar vertebrae (L3-L5). The resulting load-displacement curves were used to extract the failure load and stiffness of each test site. Bone density was measured using lateral DEXA scans. Disc condition was determined using a four-point grading scale. Three-way analyses of variance were used to analyze the relationships between the data. The overall failure load decreased with bone mineral density (BMD) in the superior (p < 0.0001) and inferior (p = 0.011) lumbar endplates. In both endplates, the posterolateral regions were significantly stronger than more central regions. With increasing BMD, this difference became more pronounced in the superior endplates only (p = 0.005). Increased disc degeneration was associated with an overall failure load decrease in the inferior lumbar endplates (p = 0.002). The strength in the central regions of the superior endplates was reduced with increasing degeneration, but this was not observed peripherally (p = 0.001). Stiffness magnitude or distribution was not significantly affected by BMD or disc degeneration. The locations of the strongest regions of the endplate did not change with either bone density or disc degeneration. This implies that implant shapes designed using the basic structural property maps for the L3-L5 endplates are appropriate for use in patients with a wide range of pathologies, even though overall failure loads are generally lower in patients with reduced bone density and greater degrees of disc degeneration.     

The relation between vertebral endplate shape and lumbar disc herniations.

STUDY DESIGN: Blinded review of selected and un-selected computed tomographic myelograms. OBJECTIVE: To determine whether shape of the vertebral body endplate margins is a risk factor for the development of symptomatic lumbar disc herniations. The law of LaPlace for a fluid-filled tube suggests that anular tension could be related to endplate shape and a propensity for disc herniation. SUMMARY OF BACKGROUND DATA: It was hypothesized that the law of Laplace could apply to the lumbar spine because of to the cylindrical shape of the lumbar disc and its high water content in nonelderly individuals. It was further hypothesized that differences in the radius of the curvature could place stresses on the anulus that would make posterior disc herniations more likely with "rounder" endplates. METHODS: Ninety-seven contrast computed tomography scans were reviewed at transitional L4-L5 and L5-S1 in patients under 60 years of age, without previous spine surgery and without spondylolisthesis. Determinations of disc herniations and measurements of endplates were performed by blinded observers. A ratio of these measurements was used to determine the relative circularity of the endplate. Height, weight, body mass index, and disc endplate size and shape were related to the presence of disc herniation. RESULTS: By multiple logistic regression, only endplate shape was strongly related to disc herniations. Endplate area was a less significant factor in men. CONCLUSIONS: The shape of the vertebral body margin at the endplate is an important factor contributing to the development of disc herniations at L4-L5 and L5-S1.     

Geometry of thoracolumbar vertebral endplates of the human spine

Novel and better vertebral body replacement constructs are always desired by surgeons. Endplate geometry is crucial for the design of those implants, but current literature on that topic is very scarce. The authors present a morphometric study of thoracolumbar vertebral endplates, the goal of which was to analyze the geometry of endplates from T10 inferior to L3 superior by employing data from CT scans, as well as to verify the reliability of data derived from the CT measurement. Reformatted CT scans of 83 individuals were analyzed and sagittal concave angle, location of concave region, sagittal diameter of endplate, coronal concave angle, as well as transverse diameter of endplate were measured in midsagittal plane and specified coronal plane. The data of CT and cadaveric measurements of ten cadaveric specimens were also compared. Age and gender did not influence sagittal concave angle, location of concave region, and coronal concave angle significantly (P > 0.05). No significant difference has been revealed among each endplate for sagittal concave angle (range 162.5°–163.9°) and location of concave region (range 42.5–44.2%), either. Ranging between 170.9° and 175.7°, coronal concave angle was constantly larger in superior endplate than in inferior one. The sagittal and transverse endplate diameters of females were significantly smaller than those of males (P < 0.05), being about 88% of the latter one. The mean difference between CT and cadaveric measurements was small (Cronbach alpha > 0.8). Those morphologic parameters, especially the concavity of endplates, should be taken into consideration when designing novel vertebral body replacement constructs. CT measurement data could be used to calculate most suitable geometric parameters of those implants.     

The distribution of mineral density in the cervical vertebral endplates

Subsidence of various constructs into the vertebral body is a well-known complication in anterior fusion. Information on bone structure is needed, as a basis for improving these procedures. There are, however, no data available on the distribution of mineral density within vertebral endplates. In this study the regional distribution of mineralization within the cervical endplates with respect to endplate orientation (inferior and superior endplate) and level distribution (C3–C7) was examined by means of computed tomographic osteoabsorptiometry (CT-OAM). The distribution of mineralization in 80 cervical endplates of 8 spinal columns (4 male, 4 female, age range 38–62 years) in vertebrae C3–C7 was investigated by CT osteoabsorptiometry (CT-OAM). The subchondral mineralization distribution revealed considerable topographic differences within each endplate, whereby the areas of greatest density were found in the peripheral marginal zones with maxima in the posterolateral surface, whereas mineralization density was much lower in the central areas. The superior endplates showed an additional posteromedial maximum, whereas the inferior endplates showed an additional anterior mineralization maximum. Comparison of the distribution patters of inferior and superior endplates at different levels from C3 to C7 reveals a uniform increase of mineralization in the anterior portions from cranial to caudal. The mineralization distribution showed characteristic reproducible patterns. The maximal values occurred in the posterolateral parts, and can thus be considered a morphological substrate of high long-term loading. This can serve as a basis for improved prosthesis design and the anchorage point for various fusion techniques.     

Mapping the structural properties of the lumbosacral vertebral endplates

STUDY DESIGN: A biomechanical investigation using indentation tests in a human cadaveric model to seek variation in the structural properties across the lower lumbar and sacral endplates. OBJECTIVES: To determine 1) if there are regional differences in endplate strength and 2) whether any differences identified are affected by spinal level (lumbar spine vs. sacrum) or endplate (superior vs. inferior). SUMMARY OF BACKGROUND DATA: It has been postulated that some regions of the vertebral body may be stronger than others. Conclusive data, either supporting or disproving this theory, would be valuable for both spine surgeons and implant designers because one mode of failure of interbody implants is subsidence into one or both adjacent vertebrae. METHODS: Indentation tests were performed at 27 standardized test sites in 62 bony endplates of intact human vertebrae (L3-S1) using a 3-mm-diameter, hemispherical indenter with a test rate of 0.2 mm/sec to a depth of 3 mm. The failure load and stiffness at each test site were determined using the load-displacement curves. Three-way analyses of variance were used to analyze the resulting data. RESULTS: Both the failure load and stiffness varied significantly across the endplate surfaces (P < 0.0001), with posterolateral regions being stronger and stiffer than the central regions. Characteristic distributions were identified in the lumbar superior, lumbar inferior, and sacral endplates. The failure load distributions were found to differ in 1) the superior lumbar and sacral endplates (P = 0.0077), 2) the inferior lumbar and sacral endplates (P = 0.0014), and 3) the superior and inferior lumbar endplates (P < 0.0001). The sacral and inferior lumbar endplates were both found to be stronger than the superior lumbar endplates (sacrum, P = 0.054; inferior, P = 0.008) but were not themselves significantly different (P = 0.89). CONCLUSIONS: Highly significant regional strength and stiffness variations were identified in the lumbar and sacral endplates. The center of the bone, where implants are currently placed, is the weakest part of the lumbar endplates and is not the strongest region of the sacral endplate.     

Sagittal geometry of the middle and lower cervical endplates

Purpose

Construct subsidence is a relatively common complication following anterior cervical fusion. Its occurrence has been revealed to be closely related to endplate-implant contact interface. But current literature focusing on the anatomy of cervical endplate is very scarce. The purpose of this morphometric study was to analyse the sagittal geometry, especially the concavity and slope, of vertebral endplates from C3 to C7 by employing data from CT scans.

Methods

Reformatted CT scans of 97 individuals were analyzed and endplate concavity depth, endplate concavity apex location, as well as endplate slope were measured in midsagittal plane. Those specific parameters were compared among different age and gender groups. Meanwhile, comparison between superior and inferior endplate of each vertebra was also performed.

Results

Age and gender did not influence endplate concavity depth, endplate concavity apex location, or endplate slope significantly (P > 0.05). Endplate concavity depths of superior endplates (range 0.9–1.2 mm) were significantly smaller than those of inferior endplates (range 2.1–2.7 mm). Endplate concavity apex was always located in the posterior half of the endplate, with the superior one ranged from 56 to 67 % and the inferior one 52 to 57 %. Average endplate slopes of superior endplates were between 4.5° and 9.0°, and average inferior endplate slopes ranged from 4.5° to 7.5°. Among all measured segments, C5 had the largest endplate slope values, while C7 the least.

Conclusions

Superior endplate is more flat than its inferior counterpart in middle and lower cervical spine, and the concavity apex is always located in the posterior half of the endplate. Endplate slope is correlated with cervical curvature, greater slope implying more significant lordosis. These sagittal endplate geometrical parameters should be taken into consideration when investigating implant subsidence following anterior cervical fusion.     

颈椎椎间盘退变对终板结构生物力学特性的影响

目的研究颈椎椎间盘对终板结构生物力学特性的影响。方法50节颈椎标本,采用Nachemson椎间盘分级标准将标本分为4组,正常组(n=22)、Ⅰ度退变组(n=10)、Ⅱ度退变组(n=9)、Ⅲ度退变组(n=9),对每一终板平面上20个特定的测试点进行压缩实验,直径2mm的半球形压头以003mm/s的速度垂直于终板平面下压2mm,由所得的力─位移曲线计算出最大压缩力及刚度,采用单因素方差分析、析因分析、SNK检验及相关分析对实验数据进行统计学分析。结果颈椎椎间盘退变可导致颈椎终板最大压缩力及刚度的显著性减小(P<001),且存在负相关关系(分别为rs=-0429,P<0001;rs=-0244,P<0001);上终板随着椎间盘退变的加重终板平面中央承力逐渐变弱,外周承力逐渐增强,下终板的力学分布无明显改变。结论颈椎椎间盘退变是影响终板结构生物力学特性的重要因素,在进行颈椎前路融合术时应警惕由于椎间盘退变引起的“植入物沉陷”。