后纵韧带生物力学测试评价胸腰段脊柱前路减压后的稳定性

背景：到目前为止,对于后纵韧带在胸腰段脊柱前路减压术式中所发挥的生物力学稳定作用的研究未见文献报道。 目的：通过生物力学测试,评价胸腰段脊柱后纵韧带在椎管前方减压自体髂骨植骨+Kaneda内固定过程中的作用。 方法：采用7具新鲜小牛胸腰段脊柱(T₁₁~L₃)标本,采用前后对照方法,按操作过程标记为：正常组→后纵韧带完整组(椎管前方减压植骨内固定,保留后纵韧带组)→后纵韧带切除组,应用实验应力方法测试各组的生物力学特性。模拟临床手术行L₁椎体切除椎管前方减压自体髂骨植骨+Kaneda内固定,在脊柱WE-10A万能材料实验机上进行非破坏性生物力学测试,并计算应变、刚度、轴向压缩强度、扭转强刚度等数据,通过F检验分析数据。 结果与结论：胸腰椎椎管前方减压植骨+Kaneda内固定,局部切除后纵韧带使胸腰椎的稳定性在旋转、轴压、前屈、后伸、侧弯各运动状态下降,其中以前屈时最为明显,差异具有显著性意义(P < 0.05)。提示在胸腰段脊柱椎管前方减压过程中,局部切除后纵韧带将使术后脊柱稳定性在前屈状态时下降,不利于提高脊柱的融合率。因此应尽可能保留正常的后纵韧带。     

无症状成人颈胸交界区脊柱矢状面参数的相关性

背景:颈胸交界区脊柱矢状面平衡不仅与全脊柱矢状面平衡相关,还与颈椎矢状面平衡相关。目的:探讨无症状成人颈胸交界区脊柱矢状面参数的相关性。方法:选择2017年1月至2018年12月在河北医科大学第二医院体检中心行健康体检且无颈椎病相关临床症状者120名,年龄23-79岁,根据年龄分为21-40岁组、41-60岁组、61-80岁组,每组40名,均拍摄颈椎侧位DR影像,测量下面影像学参数:C2-C7矢状面轴向垂直距离、头部重心到C7椎体矢状面轴向垂直距离、胸廓入口角、颈倾角、T1倾斜角、颅倾角。结果与结论:①3组间C2-C7矢状面轴向垂直距离、头部重心到C7椎体矢状面轴向垂直距离、胸廓入口角、颈倾角、T1倾斜角、颅倾角比较差异均有显著性意义(P<0.05),并且组间两两比较差异亦有显著性意义(P<0.05);胸廓入口角、颈倾角、T1倾斜角随着年龄的增大而增大;②相关性分析显示胸廓入口角、颈倾角、T1倾斜角与年龄呈正相关(r=0.622,r=0.439,r=0.533,P均<0.001);胸廓入口角与T1倾斜角呈正相关(r=0.569,P<0.001);胸廓入口角、T1倾斜角均与C2-C7矢状面轴向垂直距离呈负相关(r=-0.725,r=-0.352,P均<0.001);③结果表明,无症状成人胸廓入口角、颈倾角、颅倾角、T1倾斜角呈随年龄增大而增大的趋势,且胸廓入口角、颈倾角、T1倾斜角与年龄呈正相关。     

基于脊柱矢状面曲线建立腰椎 L4 ~ 5 力学简化模型及其有效性验证

目的 根据人体脊柱矢状面曲线建立腰椎 L4~ 5 活动节段力学简化模型,对该模型结构进行有效性验证与分 析。 方法 采用基于飞行时间测距原理的体外测量装置获取人体脊柱矢状面曲线,基于该曲线构建腰椎 L4 ~ 5 机 械简化模型,并从关节活动度(range of motion, ROM)、椎间盘应力( intervertebral disc pressure, IDP)分布及小关节 力(facet joint force,FJF)方面对模型有效性进行验证。 结果 在 0. 2、0. 4、0. 6、0. 8、1 kN 随动载荷( follower load, FL)下模型最大 IDP 分别为 0. 23、0. 46、0. 69、0. 92、1. 15 MPa,纯扭矩下模型屈曲、后伸、侧屈及轴向扭转时 ROM 分 别为 6. 61°、4. 03°、3. 30°、2. 03°,在 FL 和扭矩共同作用下屈曲、后伸、侧屈及轴向扭转时 IDP 分别为 1. 80、1. 00、 1. 36、0. 80 MPa,后伸、侧屈及轴向旋转时 FJF 分别为 79. 60、29. 49、94. 64 N。 结论 基于人体脊柱矢状面曲线构建 的力学简化模型可用于脊柱矢状面曲线变化的脊柱力学分析。     

经椎弓根截骨螺钉固定修复胸腰椎后凸畸形:脊柱-骨盆参数的相关性分析

背景:退变性胸腰椎后凸畸形患者因矢状面失平衡导致腰痛,进而严重影响其生活质量,截骨矫形重建此类患者的矢状面尤为重要。目的:探讨经椎弓根椎体截骨矫形螺钉置入内固定修复退变性胸腰椎后凸畸形患者术后生活质量与脊柱-骨盆参数变化的关系及临床意义。方法:回顾性分析2010年5月至2014年10月在河北省沧州中西医结合医院行L2经椎弓根椎体截骨矫形螺钉置入内固定的59例退变性胸腰椎后凸畸形患者的临床资料。所有患者手术前后均摄站立位全脊柱正侧位X射线片。统计测量所有患者术前、术后X射线平片的胸椎后凸角、腰椎前凸角、T1骨盆角、矢状面平衡、骨盆投射角、骶骨倾斜角和骨盆倾斜角;术前术后运用SF-36量表评估患者的生活质量并进行对比。结果与结论:(1)脊柱-骨盆相关参数中,除骨盆投射角外,其余参数手术前后相比差异均有显著性意义(P0.01);就SF-36量表各维度而言,术后评分均高于术前(P0.01);(2)腰椎前凸角的变化与骨盆倾斜角、骶骨倾斜角、矢状面平衡存在线性相关,骨盆倾斜角的变化与骶骨倾斜角、身体疼痛维度及总体健康状况维度存在线性相关,矢状面平衡的变化与腰椎前凸角、身体疼痛、总体健康状况存在相关性,T1骨盆角的变化与腰椎前凸角、矢状面平衡、身体疼痛及总体健康状况也存在相关性;(3)结果表明,经椎弓根椎体截骨螺钉置入内固定能够有效重建退变性胸腰椎后凸畸形患者的脊柱-骨盆矢状面形态,缓解疼痛,显著改善患者的生活质量。     

MRI在胸腰段骨折合并后侧韧带损伤中的诊断价值

目的　评估矢状面脂肪抑制 T2加权像 MRI在胸腰段骨折合并后侧韧带损伤中的诊断价值。方法　对 34例胸腰段骨折的患者 ,术前均进行了棘突间触诊、X线平片及 MRI等检查。除常规 MRI检查外 ,还增加了矢状面脂肪抑制 T2加权像。手术选择后侧入路 ,术中仔细探查后侧韧带的复合损伤。结果　 14例患者触诊发现棘突间距离增大 ,2 1例行 X线平片检查出现相同结果 ,30例 MRI检查高度怀疑后侧韧带复合损伤。根据 MRI的检查结果 ,2 7例患者疑有棘上韧带损伤 ,30例棘间韧带损伤 ,9例黄韧带损伤。术中探查发现 ,棘上韧带损伤 2 8例 ,棘间韧带损伤…     

脊柱侧弯拉伸矫形对漏斗胸胸廓变形影响的研究

目的研究漏斗胸合并脊柱侧弯畸形先行脊柱拉伸矫形对漏斗胸胸廓变形的影响,预测胸廓变形,有助于降低手术风险和提高手术质量。方法选择北京军区总医院胸外科1例16岁男性漏斗胸合并脊柱侧弯畸形患者胸廓CT图,采用三维重建方法重建漏斗胸合并脊柱侧弯的胸廓模型,导入ANSYS软件建立三维有限元模型,用数值模拟方法模拟侧弯脊柱拉伸矫形手术过程,分析脊柱在冠状面及矢状面的位移,并观察分析胸骨在矢状面的位移。结果矫形前的脊柱,胸椎T_3~T_4段向右(X正方向,冠状面)凸出,胸椎T_7~T_9段向左(X负方向,冠状面)凸出。对其先行脊柱拉伸矫形后,胸椎T_3~T_4段矫形后冠状面的位移场(UX)位移为-2.487 mm,胸椎T_7~T_9段UX位移为3.313 mm。脊柱矫形后,最大位移出现在与胸骨柄相连的第1肋上,最大值为13.879 mm;大于2 mm后,胸骨柄的塌陷位移增加较快,拉伸位移超过4 mm以后,胸骨塌陷位移与脊柱拉伸矫形位移呈线性关系。脊柱拉伸矫形后脊柱的最大应力为30.2 MPa,出现在胸椎T_1~T_2段;椎间盘的最大应力为7.03 MPa。矫形力最大为467.9 N,脊柱侧弯得到改善。结论漏斗胸合并脊柱侧弯畸形先行脊柱侧弯拉伸矫形会加重漏斗胸病症,临床应该先行漏斗胸微创矫形。     

保留后部韧带复合体结构对腰椎减压融合术后相邻节段生物力学特性的影响

目的比较人体腰椎标本保留后部韧带复合体(posterior ligament complex,PLC)结构在位移及载荷两种不同加载模式下对腰椎减压融合术后相邻节段生物力学特性的影响。方法 6具急性脑死亡新鲜青年男性T12~S2尸体标本,每个标本在位移及载荷加载两种模式下依次完成以下状态的生物力学测试:完整状态、L4~5椎板间大开窗减压固定、L4~5全椎板切除减压固定。通过摄像系统非接触式测量融合相邻节段运动范围(range of motion,ROM),并进行对照研究。结果在位移加载模式下,全椎板切除组屈曲ROM较椎间大开窗组显著增加,而在后伸、侧弯及旋转方面两组无显著性的差别。结论位移和载荷加载模式对腰椎融合术后相邻节段的生物力学影响存在差异性。与保留PLC结构的椎间大开窗减压方式相比,破坏PLC结构的全椎板切除减压方式可以导致相邻节段屈曲ROM显著增加,并提高相邻节段在后伸、侧弯及旋转等运动状态下ROM,其远期出现融合相邻节段失稳的可能性大。     

整体椎骨连接标本制作方法

1选材 取一段长约40cm的胸段脊柱标本,保留肋骨长约5cm,最好带3～4个腰椎.2 制作方法 修洁前纵、棘上、棘间、横突间、肋头辐状和肋横突外侧韧带.在下部腰椎矢状方向除去一个半椎体,以显露椎间盘矢状断面结构.然后上行一个椎体,从椎弓根处断离,去掉两个椎体,游离前纵韧带,保持该韧带的连续完整性,去除脊髓,显示黄韧带及水平位的椎间盘结构.再间隔一个椎体,从后部先游离棘上韧带,同样保持韧带连续完整性,然后除去二块椎板和棘突,显露椎管,去除脊髓及硬脊膜,暴露修理后纵韧带.3 讨论 以往椎间连接标本制作,大部分是将脊椎分成几段,各显示它的结构,形态教学效果不佳,整体感差,学     

腰椎管成形术的生物力学研究

目的:研究单个椎板腰椎椎管成形术对腰椎三维运动稳定性的影响。方法:选用6具成人新鲜尸体腰椎（L1~5）标本(南方医科大学解剖教研室提供),采用不同的椎管成形椎板回植技术分为6组：即A正常对照组,B椎板回植后微型钛板固定组,C椎板回植后交叉克氏针固定组,D椎板回植后双股丝线固定组,E不保留后部韧带的椎板回植微型钛板固定组,F不保留后部韧带的椎管减压组,形成6种状态,通过脊柱三维运动试验机施加10 Nm的载荷,使脊柱产生前屈/后伸,左/右侧屈和左/右轴向旋转运动,测量L3/4节段脊柱的相对运动范围。结果： 六种状态下脊柱的屈伸活动分别为(7.03±2.24)°,(7.16±2.95)°,　(7.4±2.47)°,(8.55±3.31)°,(11.1±2.81)°,(10.82±2.82)°,左右侧屈活动范围分别为(8.8±2.68)°,(8.81±2.42)°,　(8.76±1.81)°,(9.55±3.15)°,(9.12±1.97)°,(9.49±2.78)°,左右旋转活动范围(3.96±2.03)°, (5.04±2.82)°, (4.99±　2.60)°,(5.56±2.47)°,(6.03±2.62)°, (6.03±2.73)° 保留后部韧带结构椎管成形不保留后部韧带及椎管减压组组相比能够显著增加脊柱稳定性,尤其在屈伸活动状态下（P<0.05）,其中丝线固定同其他两种固定方式相比对脊柱三维稳定性影响最大（P<0.05）,微形钛板成形及克氏针固定组对脊柱稳定性影响最小。结论: 椎管成形后固定效果较为可靠的是微型钛板及克氏针固定,单纯骨性椎管成形不保留后部韧带和椎板切除椎管减压均显著降底脊柱初期稳定性,椎管成形术需可靠修复后部韧带复合体。     

胸椎T_(10)骨肿瘤转移不同位置生物力学特性的三维有限元分析

背景:随着检查技术的革新,不同分期脊柱转移瘤患者逐年增多,经皮椎体成形是脊柱转移瘤重要的治疗手段,但其治疗不同分期、不同活动方式肿瘤的术后生物力学疗效尚未见报道。目的:基于三维有限元模型模拟胸椎T_(10)骨肿瘤转移不同位置的应力及位移情况。方法:根据1例30岁健康男性胸椎三维CT扫描数据,采用Mimics软件构建胸椎(T_(9)-T_(11))的三维几何模型,包括肋骨、韧带及椎间盘。模拟被胸椎转移瘤侵袭的T_(9)-T_(11)椎体及其后胸椎不同部位的三维模型,包括椎体结构完整的对照组,单侧转移累及椎体区(实验组1),单侧转移累及椎体和椎弓根区(实验组2),单侧转移累及椎体、椎弓根和横突区(实验组3),双侧转移累及椎体、椎弓根和横突区(实验组4)。利用Abaqus软件创建三维有限元模型,对负重、屈曲、伸展、旋转工况下VonMises应力分布及模型的位移情况进行分析。结果与结论:①在对不同实验组加载点在负重、屈曲、伸展、旋转工况下最大总位移的研究中,随着转移瘤侵袭部位及侵袭面的增多,加载点的总位移在增大,整体刚度降低,尤其实验组4加载点的总位移最大;②在屈曲工况下椎体、椎弓根破坏后明显增加最大Von Mises应力值,而在此基础上增加胸肋关节破坏,其最大Von Mises应力值基本不变;③有限元分析并模拟骨肿瘤模型的基础上,将骨水泥区域的单元设置为一个单独的set集合,后将骨水泥区域设置为对应的材料属性以模拟骨水泥填充,结果发现,负重、屈曲、伸展、旋转工况下最大总位移均小于各实验组;④模拟经皮椎体成形治疗后患者在负重、屈曲、伸展、旋转工况下的最大应力值相较于骨肿瘤模型大幅度降低;⑤提示基于胸椎T_(9)-T_(11)的三维有限元模型构建有利于对胸椎骨肿瘤转移生物力学特性的研究,并能够在胸椎骨肿瘤转移模型的基础上准确模拟经皮椎体成形后加载点在不同工况下的总位移及最大VonMises应力情况。     

腰椎后部韧带结构生物力学实验研究与临床意义

目的；通过生物力学测定了解腰椎后部韧带结构对腰椎稳定性的影响。方法：本文采用５具正常青年人新鲜腰椎标本，去除肌肉，保留韧带，经逐步处理分为三组，Ａ组：正常组；Ｂ组；切除棘上韧带组；Ｃ组；切除棘上，棘间韧带组。以生物力学方法研究后部韧带结构切除后腰椎稳定性的变化。     

有限元分析腰椎传统椎弓根钉道和改良皮质骨钉道的生物力学性能

目的 通过有限元分析传统椎弓根钉道（traditional trajectory, TT）和改良皮质骨钉道（modified cortical bone trajectory, MCBT）在骨质疏松椎体上的力学性能。方法 建立L4椎体三维模型,在椎体两侧分别模拟置入椎弓根螺钉（pedicle screw,PS）（直径6.0 mm,长45 mm）和MCBT螺钉（直径4.5 mm,长40 mm）。比较螺钉在两种钉道上、下、左、右4种工况下载荷位移比和螺钉抗拔出力,评价在骨质疏松条件下螺钉和椎体之间的稳定性。结果 MCBT螺钉抗拔出力比PS提高13.1%。MCBT螺钉在上、下、左工况下载荷位移比相比PS分别提高57.1%、32.3%、31.6%,MCBT螺钉在右工况下载荷位移比虽高于PS,但不具有统计学差异。在轴向旋转和侧屈工况下,MCBT组椎体载荷位移比明显高于TT组;在前屈工况下,MCBT组椎体载荷位移比低于TT组;在后伸工况下,MCBT组椎体载荷位移比虽高于TT组,但不具有统计学差异。结论 MCBT在抗拔出力、螺钉稳定性、椎体轴向旋转和侧屈的稳定性优于TT,但在椎体前屈和后伸稳定性弱于TT。研究结果论证了MCBT在骨质疏松条件下的优越性,为MCBT的临床应用奠定前期基础。     

3D morphometry of the transverse and alar ligaments in the occipito-atlanto-axial complex: an in vitro analysis

This study verifies the three-dimensional anatomical features of the transverse and alar ligaments with reference to the axis using a direct in vitro approach. In 20 fresh spine specimens, metal markers were inserted on the cranium, atlas, and axis. After registration of the intact specimen, the bony segments were separated, and markers and anatomical landmarks were digitized. The length and the orientation of the ligaments with reference to the axis were derived from the relative position data. The transverse ligaments of the atlas have a mean estimated length of 21 mm and an absolute angle (i.e., independent of any reference frame) of 119 degrees +/- 17 degrees . The alar ligaments have a mean length of 9 +/- 2.5 mm, and the mean absolute angle between the ligaments is 117 degrees +/- 31 degrees . The plane of the alar ligaments shows a mean backward inclination of -10 degrees +/- 52 degrees . This plane has a mean inclination of 6 degrees +/- 4 degrees with reference to the sagittal plane indicating left-right symmetries. The transverse ligament arches around the dens and demonstrating its function as a stabilizer for the dens as well as guidance for axial rotation movements. A posterior inclination of the alar ligaments may induce a coupled extension in combination with a lateral bending during axial rotation. These detailed aspects of motion steering may be important to consider when attempting to reduce or restore movement.     

颈椎人工椎间盘置换有限元分析

目的　建立C4~5节段PrestigeTM-LP颈椎人工椎间盘植入后的三维有限元模型,进行手术节段的运动分析。 方法 采用对成年男性的新鲜尸体的颈椎标本进行CT三维扫描方法建立C4~5节段和PrestigeTM-LP人工间盘有限元,模拟完成C4~5人工椎间盘置换手术。测量生理加载下手术节段前屈/后伸、侧弯及轴向旋转运动角度。结果 有限元模型对颈椎的结构,包括椎体间韧带、颈椎关节突关节、钩椎关节等均进行了精确的重建,并较好地模拟手术操作进行PrestigeTM-LP人工间盘植入。运动加载后运动角度,前屈5.7°,后伸3.5°,侧弯5.0°,旋转11.3°,与文献报道结果较为接近。 结论　有限元模型具有精确度高,手术模拟真实的特点,可作为颈椎人工椎间盘生物力学研究的一种较好途径。PrestigeTM-LP颈椎人工椎间盘置换可较好地保留手术节段的运动功能。     

Validation efforts and flexibilities of an eight-year-old human juvenile lumbar spine using a three‐dimensional finite element model

The objective of this study was to develop a finite element model of the lumbar spinal column of an eight-year-old human spine and compare flexibilities under pure moments, adult, and pediatric loading with different material models. The geometry was extracted from computed tomography scans. The model included the cortical and cancellous bones, growth plates, ligaments, and discs. Adult, adolescent, and pediatric material models were used. Flexion (8 Nm), extension (6 Nm), lateral bending (6 Nm), and axial rotation (4 Nm) moments representing adult loads were applied to the three material models. Pediatric loading (0.5 Nm) was applied under these loadings to the eight-year-old spine using adult and pediatric material models. Flexibilities depended on spinal level, loading mode, and material model. Outputs incorporating the pediatric material model responded with increased flexibilities compared to the adult and adolescent material models, with one exception. This was true for the adult and pediatric loading conditions. While the sagittal and coronal bending responses were not considerably different between the adult and pediatric loadings, axial rotation responses were greater under the adult loading. This model may be used to determine intrinsic responses, such as stresses and strains, for improved characterizations of the juvenile spine behavior.     

Evaluation of the role of ligaments, facets and disc nucleus in lower cervical spine under compression and sagittal moments using finite element method.

Cervical spinal instability due to ligamentous injury, degenerated disc and facetectomy is a subject of great controversy. There is no analytical investigation reported on the biomechanical response of cervical spine in these respects. Parametric study on the roles of ligaments, facets, and disc nucleus of human lower cervical spine (C4-C6) was conducted for the very first time using noninvasive finite element method.A three-dimensional (3D) finite element (FE) model of the human lower cervical spine, consisted of 11,187 nodes and 7730 elements modeling the bony vertebrae, articulating facets, intervertebral disc, and associated ligaments, was developed and validated against the published data under three load configurations: axial compression; flexion; and extension. The FE model was further modified accordingly to investigate the role of disc, facets and ligaments in preserving cervical spine motion segment stability in these load configurations. The passive FE model predicted the nonlinear force displacement response of the human cervical spine, with increasing stiffness at higher loads. It also predicted that ligaments, facets or disc nucleus are crucial to maintain the cervical spine stability, in terms of sagittal rotational movement or redistribution of load. FE method of analysis is an invaluable application that can supplement experimental research in understanding the clinical biomechanics of the human cervical spine.     

Validation of a Finite Element Model of the Young Normal Lower Cervical Spine

A Finite Element Model (FEM) of the young adult human cervical spine has been developed as a first step in studying the process of spondylotic degeneration. The model was developed using normal geometry and material properties for the lower cervical spine. The model used a three-zone composite disc annulus to reflect the different material properties of the anterior, posterior, and lateral regions of the annulus. Nonlinear ligaments were implemented with a toe region to help the model achieve greater flexibility at low loads. The model was validated against experimental data for normal, nondegenerated cervical spines tested in flexion and extension, right and left lateral bending, and right and left axial rotation at loads of 0.33, 0.5, 1.0, 1.5, and 2.0 Nm. The model was within in vitro experimental standard deviation corridors 100% of the load range for right and left lateral bending. The model was within 80% of the load response corridors for extension and flexion with a deviation <0.3° from the SD corridors. For axial rotation, the model was within 70% of the SD corridors for left axial rotation within 83% of right axial rotation responses. The deviation from SD corridors for axial rotation was generally <0.2°.     

基于Simpleware全颈椎三维有限元模型的构建与分析

目的 利用Simpleware软件构建全颈椎三维有限元模型,并对模型进行验证和分析,为探讨颈椎损伤机制提供可靠模型。方法 基于CT断层扫描图像,利用医学图像处理软件Simpleware、逆向工程软件Geomagic建立C1~7全颈椎三维实体模型,导入Hypermesh进行颈椎网格划分、添加韧带并引入小关节突接触关系等,建立C1~7全颈椎有限元模型,在ANSYS中模拟前屈、后伸、侧弯和轴向旋转工况下颈椎的生物力学性能。结果 建立的模型准确可靠,在前屈、后伸、侧弯和轴向旋转时,活动范围与文献中离体实验和有限元分析结果相近。椎间盘应力集中在椎体受压侧,C4/5最易产生应力集中。结论 建立的C1~7全颈椎有限元模型能够有效模拟颈椎的生物力学特性,为后续颈椎挥鞭样损伤的生物力学研究奠定良好的基础。     

Validation of the relative 3D orientation of vertebrae reconstructed by bi-planar radiography

The three dimensional (3D) reconstruction of the spine can be obtained by stereoradiographic techniques. To be safely used on a routine clinics basis, stereoradiography must provide both accurate vertebral shape and coherent position. Although the accuracy of the reconstructed morphology of the vertebrae is well documented, only few authors studied the accuracy of the vertebral orientation. Therefore, this paper focuses on the evaluation of the orientation accuracy of the reconstructed vertebrae (obtained by non-stereo corresponding point technique) considering either a 178 point vertebral model or a 6 point vertebral model (previously proposed in the literature). Five dried vertebrae were fixed on holders containing four markers each. The 3D reconstruction of both vertebrae and markers were obtained by stereoradiographic techniques. Using least square method matching from one position to another, the relative orientation was computed for the vertebral models (6 or 178 points) and the four markers. These vertebral and holder orientations were compared (considering the holder's one as reference). The repeatability of these relative orientations (vertebrae and holders) was also evaluated. The mean (RMS) orientation error of 178 point vertebral model was 0.6 degrees (0.8 degrees ), for lateral rotation, 0.7 degrees (1.0 degrees ) for sagittal rotation and 1.4 degrees (1.9 degrees ) for axial rotation. The intra-observer repeatability was 0.5 degrees (0.7 degrees ) for lateral rotation, 0.7 degrees (0.8 degrees ) for sagittal rotation and 0.9 degrees (1.2 degrees ) for axial rotation. The orientation was found more accurate and precise when using the 178 point vertebral model than when using the basic 6 point vertebral model. The relative orientation (in post-operative follow-up with respect to the pre-operative examination) of the vertebrae of one scoliotic patient was performed as an example of clinical application. The stereoradiographic method is a reliable 3D quantitative tool to assess the spine deformity, that can be used in clinics for the follow-up of scoliotic patients.