【作者】 肖进；

【导师】 尹庆水；

【作者基本信息】 南方医科大学 ， 人体解剖学， 2008， 博士

【摘要】 目的数字医学是一门以医学和数字化高新技术相结合为主要特征,涵盖了医学、数学、信息学、电子学、机械工程学等多种学科的新兴的医工交叉学科,目前这一学科已成为现代医学的重要组成部分,特别在外科领域“数字医学”已经对外科手术产生了重要变革。随着数字医学技术在临床医疗领域的不断深入与拓展,传统医学正朝着以“精确化、个性化、微创化、远程化”为主要特征的现代医学方向发展。目前数字技术在骨科临床应用日益广泛。这是一种直接融入医生个人技术中的数字化技术,必将随着数字医学的发展而迅速发展,同时成为21世纪医生的基本临床技术之一。本课题拟将数字化技术应用于骨科临床实践,共进行两个部分的研究。①脊柱侧凸是临床常见病,解剖复杂,且是包括矢状面、冠状面和水平面变化的三维立体畸形。术前了解脊柱畸形的全貌和细节对正确诊断分型、制定手术计划、确定固定节段、选择合适的椎弓根螺钉、估算螺钉进钉角度等非常重要。既是临床工作的重点,对手术治疗的成功必不可少;同时又是临床上的难点,因为以往光靠X线、CT或MR等二维影像资料难以准确评价病变的实际情况。本课题第一部分,于手术前对脊柱侧凸病人进行病变脊柱的数字化三维重建,并应用快速成型(Rapid prototyping,RP)技术制作出畸形脊柱实体,以指导临床诊断分型,手术设计及术前手术操练。②由于骨盆标本很难得到,加之其解剖结构复杂,力的传导呈各向异性,各研究者制作的骨盆标本统一性比较差等原因,用实验力学方法难以对骨盆受力作出全面而准确的分析,目前对骨盆的力学分析还处于极其粗糙的阶段。有限元法因为其结果不受样本数量限制,实验误差小,重复性好等优点,正日益成为骨盆生物力学研究的重要手段。本课题第二部分对正常成人骨盆进行数字化重建,并在此基础上对骨盆的受力及损伤机制进行三维有限元分析(Finite element analysis,FEA)。第一章脊柱侧凸的数字化三维重建及快速成型第一节脊柱侧凸的数字化三维重建材料和方法随机选取2007年7月～2007年9月收治的6例脊柱侧凸畸形患者,年龄6-21岁,平均14.0岁,其中男1例,女5例,特发性脊柱侧凸4例,先天性侧凸2例。术前均进行脊柱PET-CT断层扫描,扫描层厚1mm,获得脊柱的细间距断面图像,以DICOM格式保存于光盘;输入个人计算机,应用Mimics 8.1软件进行三维数字化重建。重建步骤包括先将数据导入Mimics,然后进行图像分割,利用软件的3D重建功能对感兴趣的部分进行重建,得到脊柱和相邻骨性结构如肋骨、骨盆等的三维重建图像。再对图像进行各种所需的观察和测量。结果本组6例患者全部进行脊柱的数字化三维重建,得到病变脊柱的三维立体图像。通过对3D模型进行旋转、平移等操作,结合观察轴位、冠状位及矢状位二维图像,可以方便地从任意角度和方向观察脊柱畸形情况,测量有关的数据:包括侧凸、后凸、旋转畸形的程度、范围、包含的节段;各椎体及附件的相邻关系、形态;椎弓根的横径、矢状径;相关骨性结构如胸廓、骨盆的毗邻关系、变形情况等等。籍此更全面、更清晰地了解病变的整体及细节。还可以在数字化模型上进行手术设计,模拟内固定器械植入操作等。第二节脊柱侧凸畸形的快速成型及临床应用材料和方法在第一节三维重建的基础上,将患者脊柱的三维重建结果以STL格式输出,应用计算机辅助逐层堆积快速成型技术,在快速成型机上以光敏树脂材料制作病变脊柱的1∶1实体模型。根据模型可以直观地了解病变脊柱的各种信息,进行手术设计,模拟打钉操作等。术中还可以将模型带入手术室,供术者参考。结果本组6例患者入院后均进行数字化人体脊柱三维重建和快速成型,全部行手术治疗。术中见畸形表现与术前重建所示完全一致,快速成型模型与病变脊柱的形态、尺寸完全吻合,准确、直观地反映了畸形病变的具体状况。所有患者均按计划完成了手术,手术过程顺利,术后效果良好,未出现神经、血管损伤等并发症。术后X线和CT复查矫形效果满意,显示椎弓根螺钉位置正确。结论随着数字化人体技术和快速成型技术的飞速发展,将之应用于脊柱病变的诊断和治疗成为可能。本研究证明了这一技术应用于临床的可行性和可靠性。对脊柱侧凸患者,临床医生采集CT扫描数据进行数字化三维重建,利用快速成型技术生成实体模型,可以直观地观察脊柱畸形的具体病变情况,进行手术计划,模拟手术操作,还可以更有效地与患者及家属进行沟通。加深了医生对疾病的理解,促进了手术治疗效果的提高。第二章骨盆的数字化重建及三维有限元分析第一节骨盆三维有限元模型的建立材料和方法一例中年男性正常志愿者(35岁),经X线、B超检查排除骨盆损伤、肿瘤、畸形等病变,进行PET-CT扫描,层厚1mm,得到的二维原始图像以DICOM格式输出,导入个人电脑。采用Mimics 8.1软件进行骨盆的数字化三维重建,包括图像输入、分割、三维重建等步骤,结果以STL格式输出(参考第一章内容)。然后进行三维模型的后处理:利用Freeform软件对模型进行平滑、除噪点、铺面等修饰处理,结果以有限元分析软件能够接受的IGES格式输出。将经过Freeform软件修饰后的IGES格式存贮的骨盆三维实体模型导入到有限元分析软件ANSYS 9.0中,定义模型的单位,设定实常数,定义材料属性,添加韧带等骨盆附属结构,进行网格划分,最终建立有限元模型。结果在ANSYS软件中得到了一个完整的骨盆有限元模型,包括骨性结构及韧带、关节软骨等组织。该模型共建立节点241277个,单元155194个。可以在此基础上对骨盆进行加载,破坏,模拟各种手术(如复位、上内固定等)操作等。第二节骨盆静载荷作用下的有限元分析材料和方法在第一节中建立的骨盆有限元模型中,模拟人体双腿直立位的生理姿势,向骨盆施加轴向载荷。具体方式为约束双侧髋臼,向骶骨椎体上表面垂直加压,压力均匀分布于各个结点。所加载荷大小为500N,在ANSYS软件中进行非线性应力分析求解。完成之后进行应力、应变、位移等分析求解过程,求解结束之后采用该有限元分析软件的后处理功能,得出应力云图、应变云图、位移云图等结果,结合临床进行结果分析。结果两侧髂骨应力分布情况完全一致,应力经两侧骶骨翼、骶髂关节,斜向下方经过坐骨大切迹附近,髂骨中央弓状线,传导至两侧髋臼。其中以骨盆背面坐骨大切迹附近所受应力最大,为0.434E+07(Pa)。骨盆前环即耻骨支和耻骨联合受力较小。表明骨盆的主要负重和稳定结构位于后方,前方结构的功能以支撑为主。应变集中在两侧骶髂关节,绝对值很小,约0.004527-0.022633,前方的耻骨联合处应变极小,可忽略不计;其余骨性部分无应变。骶骨背侧的骶正中嵴位移最大,达0.164E-03m(即0.164mm)。以此为中心,移位向两侧扩散直至髂骨翼部分逐渐减弱至0。第三节外旋应力作用下骨盆的三维有限元分析材料和方法在第一节建立的骨盆有限元模型中,约束骶骨,向左侧髂前上棘施加500N水平向后的载荷,模拟骨盆受到外旋应力时的受力情况。结果在外旋载荷作用下,应力沿两条途径传导:一条是向内后方经同侧骶髂关节前部至骶骨上部,另一条是向前方经同侧耻骨支、耻骨联合至对侧耻骨。最大应力出现在同侧骶骨岬部,为0.240E+08(Pa),最小应力出现在同侧骶髂关节上半部。与垂直加载时应力分布不同的是,在此状态下骨盆前环受力较大。利用ANSYS软件的切割功能,单独对小骨盆进行应力分析,发现在骨盆前环中,同侧耻骨上支中段偏前下方处应力为前环中最大的,为0.0142E+08(Pa),对侧耻骨上支中段及两侧耻骨下支所受应力也比较大。同侧骶髂关节前下方应变最大达0.35,后上方应变最小;对侧骶髂关节应力很小。前方的耻骨联合处应变也较大,达0.22。位移以受力点—该侧髂前上棘处最大,达0.0035m。同侧的髂骨、坐骨及耻骨支位移均较大,对侧耻骨支及髂骨外侧半位移较小。位移最小的部位是同侧骶髂关节上半部。第四节骨盆损伤内固定的三维有限元分析材料和方法在骨盆有限元模型中,模拟一侧骶髂关节脱位后,于受伤侧关节前方上接骨板螺钉内固定。对内固定的骨盆分别施加500N轴向载荷及外旋载荷,进行受力分析。结果垂直加载时,内固定系统处产生了应力集中,其最大应力达0.599E+09(Pa),约为正常骨盆的100倍。同时,损伤侧关节因固定而失去了变形性,应变由完整骨盆的两侧关节对称变为仅正常侧关节存在应变。位移分布图则显示固定侧骶髂关节是整个骨盆中位移最大的部分,达0.342mm。在外旋应力作用下,内固定系统处同样存在应力集中,达0.265E+10(Pa)。此时应变以前方的耻骨联合处最大,是骨盆完整时该处应变的大约4.5倍。位移分布与完整状态下的骨盆基本一致,受力点处(左侧髂前上棘)位移最大,内固定侧骶髂关节的位移极小,与正常状态下相似。结论本研究采用正常成年男性骨盆CT扫描的数据,输入PC机后通过Mimics软件重建数字化模型,结果再导入ANSYS软件进行三维有限元建模和有限元分析。在垂直应力和外旋应力这两种加载状态中,骨盆的应力、应变及位移变化趋势与采用尸体标本的实验研究及理论认识基本一致,充分说明了模型的有效性和可靠性。并以该模型为平台,模拟骨盆损伤(一侧骶髂关节脱位)及内固定情况,分析骶髂关节前方钢板固定的稳定性。今后还可以进一步利用这一模型来全面地对骨盆进行分析,如骨折、骶髂关节脱位、内固定、部分切除等各种情况下的变化。更多还原

【Abstract】 ObjectivesDigital medicine is a new medicine- engineering cross subject.It is characterized by a combination of medicine and digital technique.This subject is comprised of medicine,mathematics,information,electronics,mechanics- engineering,et al. Nowadays digital medicine has been one of the important parts of modern medicine. Especially in surgery this subject has caused great revolution.With digital medicine goes deep into and expands in clinical fields,traditional medicine is running to modern medicine,which is characterized by Precision,Personality,Micro-trauma and Long range.At present orthopedists apply digital technique in clinical fields generally. Digital technique is one of doctors’ personal techniques and it will develop with the development of digital medicine.This will be one of doctors’ basic clinical techniques in 21 century.This study wants to use the digital technology in clinical orthopedics.It contains two departments:(1) Scoliosis is a frequent disease.It has a complicated anatomy and is a kind of three dimensional(3D) deformity in sagittal plane,coronal plane and transverse plane.It is very important to understand the entirety and details of the abnormal spine before operations.This can help us to diagnose and type correctly, make the operation plan,determine the fixation segments,choose suitable pedicle screws,estimate the angles of screws,et al.It is both the emphasis and the difficult point of scoliosis treatment.In the past time doctors had to use X-ray/CT/MR data to do this job,but all these examinations were two dimensional and they can’t be used to evaluate the actual information of 3D spine.In part one,we carried out digital 3D reconstruction of deformity spine of scoliosis patients.Then entities of the spines were made using Rapid Prototyping(RP) technology.We utilized the models to guide diagnosis and typing,design operation program and simulate handlings in operation. (2) At present the biomechanical analysis of pelvis by experiment is crude for these reasons:it is difficult to get pelvis specimens,the anatomy structure is very complicated,the conduction of force is anisotropic,specimens made by different persons are various,et al.Nowadays Finite Element Method(FEM) has being an significant device.FEM can get results without many specimens and the experiment error is few.Furthermore FEM is good at reproducibility.In part two,we carried out digital reconstruction of pelvis of a normal adult.Then we analyzed the mechanism of bearing load and damage by FEM.Character One Digital 3D reconstruction and Rapid Prototyping of scoliosis Section One Digital 3D reconstruction of scoliosisMaterials and methods6 patients with scoliosis were chosen randomly from July to September,2007. They were 6 to 21 years old with average 14.There were 1 male and 5 female patients,with 4 were idiopathic scoliosis(IS) and 2 were congenital scoliosis(CS). They all accepted PET-CT scanning of spine before operations with the scanning interval of 1 mm.The cross- section images were preserved in disc by DICOM (Digital Imaging and Communications in Medicine) pattern.Then they were imported into personal computer(PC) and dealt by Mimics(Materialise’s Interactive Medical Inage Control System) 8.1 software.From this data a 3D model of pelvis was reconstructed using Mimics.The steps of digital reconstruction in Mimics contained input and segmentation of images,reconstruction of interested portions,et al.Then the digital 3D recon- struetion images of spine and the skeleton structures nearby were got,such as ribs and pelvis.Subsequently we could do various kinds of observation and measuring to the model.ResultsAll 6 patients in this group were undertaken digital 3D reconstruction of spine before operations.We got their 3D images of abnormal spines.Then we could rotate or translate the 3D model to observe the deformity of spine with the 2D images of sagittal,coronal and transverse planes from any angle conveniently.Also we measured every kinds of data from the images,such as angles of scoliosis,kyphosis or rotation of the spine,extent or segments of the deformity,forms or relationship of vertebral bodies and appendixes,transverse or sagittal diameters of pedicles,the deformity of bony thorax or pelvis,et al.So we could understand the global and details of abnormal spine generally and distinctly.The digital model could also help us do surgery design and simulate the manipulation of internal fixation.Section Two Rapid Prototyping of scoliosis and clinical application Materials and methodsBased on Section One,we output the 3D digital reconstruction model of deformity spine in STL pattern.Then a concrete model of the same spine,which was as equal to the real one,was made by photosensitive colophony using rapid prototyping machine.In this process,the RP technique with compute-assistant and each layer accumulation was utilized.We could realize various kinds of information of the deformity spine from the concrete model directly.And it could be used to design operation program,stimulate the handling of installing screws,et al.The model could also be taken to the operating room and be consulted by surgeon during the operation.ResultsAll 6 patients in this study were undertaken digital 3D reconstruction and rapid prototyping of their spine and every one accepted operations.During the operations we found that the deformity was as same as the reconstruction model before.The appearance and size were completely accord by RP model and real spine.The RP model reflected the concrete information of the abnormal spine exactly and directly. Every patient was operated successfully according to the plans before.The processes of operation were success and the effects were excellent after treatment.There wasn’t any syndrome of nerves or vessels.After operation the exhibition of X-ray and CT scanning were satisfying,and the position of pedicle screws were accurate.ConclusionWith the high speedy development of digital medicine and RP technique,they were possible to be used in the diagnosis and treatment in spine diseases.Our study proved the feasibility and reliability of the using of these techniques in clinical practice.Doctors could collect the data of CT scanning to reconstruct the deformity spine digitally to scoliosis patients.Then they made concrete models of the spine using RP technique.Using the RP model,doctors could observe the whole and details of the deformity spine directly from the model,design the operations,stimulate the surgery manipulations and communicate with the patient and his families.At the same time,the RP model made doctors understand the disease deeply and improve the treatment results of operations. Chapter Two Digital reconstruction and three-dimensional FEM analysis of pelvisSection One Establishment of the three-dimensional Finite Element model of pelvisMaterials and MethodsOne common volunteer who was male adult was chosen.He had been got rid of trauma or tumor or deformity of pelvis by X-ray and B-ultrasound examination.Then he got PET-CT scanning.Scanning thickness of each slice was 1 millimeter.The initial two dimensional images of pelvis were output in DICOM format to PC.The digital reconstruction of pelvis based on the data was made by Mimics 8.1 software. The process of reconstruction contained images been input,segmentation of images, pelvis reconstructed,et al.The results were output by STL format(See Chapter One). Then the 3D model accepted post-processing with the software of Freeform.We could modify the 3D model by Freeform,such as smoothening,removing noise and surface-meshing,et al.The results were output in the format of IGES which could be used directly by the software of FEM.Finally the 3D model of pelvis was import by the FEM software of ANSYS 9.0.Through ANSYS we could give units,set up the solid constants,definite the pattern of materials,add ligaments to the pelvis,et al.At the end the model was meshed and a FEM model occurred.ResultsWe got a complete FEM model in ANSYS.He model contained bone structure and some accessory such as ligaments,articular cartilage.This model possessed 241227 nodes and 155194 elements.Based on it people could exert load or damage to the pelvis,or stimulate the processes of operation,such as reset the fracture or fixation,et al.Section Two Finite Element Analysis of Pelvis under static loading Materials and MethodsIn the FEM model of pelvis built in Section One,axial loading were put to it. The model simulated the posture when the body was erecting by two legs.The loading was put to the supine surface of sacrum perpendicularly and distributed to each node averagely with both sides of the acetabulum were constrained.The loading was 500N and the none-line solution was analyzed.After that the stress and strain and displacement nephograms were obtained with the function of post-processing module in ANSYS.At the end the biomechanical stability and intensity of pelvis were analyzed and compared.ResultsThe distribution of stress in two sides of iliac bones was equal.The stress past the ala of sacrum and the sacroiliac joint to the regions near the greater sciatic notch. Then it past the arcuate line to the acetabulum.The peak of stress was 0.434E+07(Pa), appeared at the region near the greater sciatic notch.The stress at the anterior ring of pelvis was small.This result indicated that the main weight loading and stability structure was at the posterior part of pelvis.On the other hand function of the anterior part was supporting mainly.The strain concentrated at two sides of the sacroiliac joints,and it was very small just 0.004527-0.022633.The strain at pubic symphysis was little very much and it could be ignored.The strain of bone was almost zero.The peak value of displacement appeared at the median sacral crest.It was 0.164E-03m (0.164mm).The displacement extended to two sides until the iliac ala.And it gradually reduced to zero from the center to the side.Section Three Three Dimension FEM Analysis of pelvis under Extorsion loadingMaterials and MethodsIn the FEM model of pelvis built in Section One,the loading of 500N was given to the left anterior superior iliac spine.The direction of the loading was flatly rearwards.This state simulated the loading of pelvis when it was paid extorsion loading.ResultsThe stress transmitted in two ways.In the first way it was rearwards to the superior part of the sacrum past the sacroilial joint at the same side.In the second way the stress passed forward to the pubis at opposite side.In the way it past the pubis and pubic symphysis at the same side.The peak value of stress appeared at the promontory of the same side of sacrum.It was 0.240E+08(Pa).The minimum of the stress appeared at the supra-half of sacroilial joint at the same side.The loading of the anterior ring of pelvis was relatively greater than it was perpendicularly.The stress of the real pelvis was analyzed alone using the function of segment in ANSYS.We found that in the anterior ring of pelvis the stress at the medium of upper branch of pubis at the same side was greatest,and it was 0.0142 E+08(Pa).Similarly the stress at the medium of upper branch of pubis at the opposite and at the lower branch of pubis at both sides was greater.The peak value of strain appeared at lower- forward of the sacroi- lial joint at the same side and it reached 0.35.While it was smallest at supra- rearward of the sacroilial joint.And it was smaller at the sacroilial joint opposite.The strain at pubic symphysis was greater and it reached 0.22.The peak value of displacement was at the point of loading and it was 0.0035m.The displacements at ilium,ischium and branch of pubis at the same side were relatively greater.And it was smaller at the branch of pubis and the half part of ilium lateral opposite.The smallest value appeared at supra- half part of the sacroilial joint at the same side.Section Four Three Dimension FEM Analysis of internal fixed pelvisMaterials and Methods In the FEM model of pelvis built in Section One,one of the sacroiliac joints simulated dislocation.Then an internal fixation system was installed before the injured joint.Axial loading and extorsion loading were put to the pelvis in turn.The loading was 500N.Then the none-line analysis was carried out.ResultsThe internal system generated stress concentration under axial loading.The max of stress was 0.599E+90(Pa) which was as much as 100 times than the equal state of the normal pelvis.At the same time only the normal sacroiliac joint existed strain. The fixed joint lost strain at all.The max of displacement was at the fixed sacroiliac joint.The value was 0.342mm.The internal system existed stress concentration similarly under extorsion loading and the value was 0.265E+10(Pa).The maximal value of strain appeared at the pubic symphysis.The strain was as 4.5 times much as the normal pelvis.The distribution of displacement was similarly as the normal pelvis.The displacement of the point of bared loading was largest and it was very small at the fixed sacroiliac joint.The distribution was as similar to the normal pelvis.ConclusionsWe utilized the data of CT scanning of pelvis which was from a normal male adult.The data was input to PC and was reconstructed to digital model in Mimics. Then the results was imported to ANSYS and been analyzed by FEM.We gave loading perpendicularly and extorsion loading to the pelvis model.In the two situations the tendency of changing of stress,strain and displacement was according to it in experiments using specimens in vitro or in the theories.It proved the efficacy and reliability of the 3D finite element model.Then we simulate the state of dislocation of one sacroiliac joint and been internal fixed.The stability of internal fixation was analyzed.Afterward we will use it to analyze every situations of the pelvis all-sided,such as fracture,fixation,dislocation of the sacroilial joint,part excision,et al.更多还原