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1、 标准步态下骨盆三维有限元模型构建及其生物力学意义 作者：汪光晔，张春才，许硕贵，任可 【关键词】 骨盆；三维有限元；髋臼作用力；骨盆肌肉收缩力Threedimensional finite element pelvic modeling during standard&nbs
2、p; gait and its biomechanical significances【Abstract】AIM: To construct a threedimensional (3D) finite element pelvic model which includes both 3D pelvic muscle and acetabular contact forces during standard gait. METHODS: A normal pelvisfrom an adult male subject was scanned by CT and the images of e
3、very crosssection were obtained. A pelvic model including both threedimensional pelvic muscle and acetabular contact forces during standard gait wasconstructed with PATRAN 2005R2 software. RESULTS: The constructed 3D finite element pelvic model clearly reflected the real pelvic anatomy a
4、nd biomechanical behavior, especially the muscle force and hip contact force. The model was divided into 113 028 nodes and 137 524 units. CONCLUSION:The construction of 3D finite element pelvic model provides basic data which are critical for accurately modeling either normal loads or stresses and s
5、trains, or the effects of abnormal conditions.【Keywords】pelvis; threedimensional finite element; acetabular contact force; pelvic muscle force【摘要】目的： 构建包含骨盆肌肉及头臼作用力的标准步态下骨盆三维有限元模型. 方法： 选择标准成年男性志愿者行骨盆CT扫描成像得到骨盆每层横截面图像, 运用Mimics软件行三维重建， 利用有限元分析软件PATRAN 2005R2构建髋臼三维有限元模型,并将标准步态中肌肉收缩力及头臼作用力也设计到该模型
6、中. 结果： 所构建髋臼模型共划分为113 028个结点、137 524个单元, 模型模拟了骨盆皮质骨、松质骨、关节软骨以及股骨头结构的材料特性. 所建模型结构完整，空间结构测量准确度高，单元划分精细，重点突出，尤其肌肉及头臼作用力加载模拟形象、逼真，客观反映髋臼真实解剖形态结构和生物力学特点. 结论： 构建的髋臼三维有限元模型为正常髋臼或异常髋臼力学研究提供可循模型. 【关键词】 骨盆；三维有限元；髋臼作用力；骨盆肌肉收缩力0引言对于髋关节的生物力学的研究，有必要了解跨髋关节肌肉的收缩力的大小方向及部位，完整地了解髋臼接触力与骨盆肌肉收缩力力学机制，有助于进一步模拟髋关
7、节力学行为、解剖学与手术后改变的影响，虽然有文献1-3讨论过骨盆髋臼生物力学行为，然而这些先前的模型或没包括髋臼接触力或不包括肌肉收缩力. 因此其结果已受到大多学者的质疑. 作为实验研究骨盆与髋臼负载的需要，本实验试图报导一个既包含了肌肉又包含了髋臼接触力的三维有限元模型，这些数据将对于准确模拟髋关节与骨盆的正常负载或异常负载将尤为重要. 1材料和方法1.1材料 成年男性志愿者骨盆（男性，40岁）； 西门子SOMATOM Volume Zoom CT 机；DELL工作站；Mimics软件；Patran 2005 r2 软件； Windows XP操作系统. 1.2方法1.2
8、.1骨盆三维有限元模型构建具体可以分为3个步骤 步骤一： 对一成年男性志愿者（40岁）的骨盆进行CT断层成像；在CT成像过程中要志愿者在骨盆纵轴方向保持不动，每隔1 mm层厚扫描一次. 所得图像以DIMCOM格式存入CT机，刻录光盘，从而得到表示骨盆每层横截面的图像. 步骤二： 将上述以DIMCOM格式存储的图像导入Mimics软件，设定门槛下界灰度值为270，上界不限. 通过Region growing 选择感兴趣区域，进行骨盆三维重建. 有限元分析与计算： 三维重建图像以out格式导出，并导入Patran 2005 r2软件，并重新进行网格划分，建立皮质骨的外表面与内表面，其内外表面都相互
9、连接，分别建立骨盆的皮质骨及松质体模(图1). 与骨盆骨相互作用的股骨头也被建模，此外关节软骨也被建模，以保证一个光滑且真实的髋关节作用力的加载4，除了髋关节头臼作用力(表1)，22块附着在骨盆上的肌肉也被设计到该模型中(表2，图2)，肌肉的生理附着点被绘制到有限元网格中，其相关参数皆来自于Pedersen1997年的研究结果5.图1髋臼皮质骨(A)与松质骨(B)有限元模型略表1步态循环中支撑相时负载受力参数略 1.2.2设置单元属性根据骨盆的解剖结构特点，骨性结构模拟材料为皮质骨、松质骨、软骨下骨及关节软骨，材料参数的选择参考文献6-7（表3）.1.2.3加载情况固定骶髂关节处的节
10、点模拟骶骨的支持，只1对左半侧骨盆进行加载，在耻骨联合处模拟弹性边界条件. 根据步态循环周期中左支撑相的第4个子步相的髋关节的头臼之间的作用力,从股骨头的中心点处进行加载. 此外肌肉收缩力也被考虑，收缩力的方向是根据远近端的附着点获得8，并且步态中骨盆肌肉与股骨的相对位置关系也被考虑进去. 本实验中设定股骨头内收15，同时在前后位上骨盆与股骨头(髋关节的伸屈)的角度是可以变化的(表1). 肌肉的收缩力以分布载荷运用到模型的表面，肌肉的收缩力的方向是由其远近端的生理附着点的连线，并同时兼顾髋关节的屈伸角度对远端生理附着点的坐标影响. 假设条件:本实验所涉及的生物材料均假定为均质、连续和各向同性.
11、 受力时模型各截面不产生相互滑动，各单元有足够的稳定性;材料受力变形为小变形.表25步态载荷中肌肉收缩力的大小(略) 表3骨盆三维有限元模型单元属性表略2结果2.1模型建立本研究中，应用CT图像专用的DICOM医学数字图像通讯标准，CT专用的Mimics图像识别分割建模软件和PATRAN有限元专用软件，将薄层CT横断面图像进行分割识别，建立了适合生物力学研究的髋臼三维有限元模型(表4，图1)，肌肉的生理附着点被绘制到有限元网格中，并由肌肉的远近端的附着点获得肌肉收缩力的方向，并兼顾髋关节的屈伸角度对远端生理附着点的坐标影响(图2). 髋臼三维有限元模型共划分为113028个单元，13
12、7524个节点. 股骨头采用四节点tet10单元，共划分为37090个单元50392个节点. 松质骨模型在髂骨中央有椭圆形孔，及髂前下棘处有缺失，既该两处为皮质骨充满. 旋转观察模型形态与骨盆解剖形态具有满意的相似性，可任意切割和调整几何及材料参数以模拟不同临床与实验状态. 表4模型的有限元如下表略2.2模型的受力分析模拟步态4髋关节的头臼之间的作用力及附着在骨盆上的22块肌肉的收缩力对模型进行加载. 得到该情况下髋臼的力场分布(图3). 结果显示：主应力集中在髋臼软骨的臼顶区，传递至软骨下骨后，沿弓状线及臼顶的外上皮质至骶髂关节.3讨论3.1骨盆有限元模型的应用1995年Dals
13、tra等首次详细报告了骨盆三维有限元模型. 2000年Garcia等应用三维有限元对内固定后的骨盆进行应力分析，研究骨盆骨折后不同固定对其稳定性的影响；2006年Yew运用有限元分析影响髋关节假体置换稳定性的因素9. 国内张春才等10报道了应用三维有限元法对骨盆骨折损伤机制的分析. 在骨折内固定的应力分布、人工关节的设计优化研究，骨折危险性预测、骨折愈合、预测骨的塑型以及骨质疏松症研究方面有限元模型已是不可缺少的方法7.图3单腿站立位时皮质骨(A),松质骨(B)和髋臼软骨(C)受力分布略本研究应用16排螺旋扫描 CT扫描，并用MIMICS软件直接读取DICOMR的CT文件，选取兴趣区域行3D计
14、算，获得髋臼的三维模型，并导入MSC公司PATRAN软件，建立了髋臼的三维有限元模型，并对重点部位进行细划分. 与标本的相似程度高，形态结构准确完整. 操作过程使图像失真减少到最小. 以往4-5建立骨盆三维有限元模型采用的 CT胶片扫描或照相技术, 在对图像反复采样过程中, 图像的细节和信息在采样过程中丢失较多, 而且工作繁重而导致建模差异较大, 出现建模质量的问题,影响到计算结果的准确性. 本实验三维建模过程为全数据化处理，避免了数据收集过程中关键信息的丢失，最大限度上保证了建模的准确性和精确性. 3.2模型的力学相似性本研究结合了结合头臼之间的作用力与肌肉的收缩力，不
15、当在外形上最大限度上保证了建模的准确性和精确性. 并且在力学加载上更与实体相似程度高，更加准确完整. 本研究头臼作用力由股骨头中心点处进行加载，同时参予髋关节运动有关的22块肌肉也被考虑，肌肉收缩力的方向由远近端附着点决定，并同时兼顾了髋关节屈伸角度对肌肉远端附着点的影响；肌肉收缩力大小与方向及头臼作用力大小与方向参考相关文献5-6,并转换为本研究的坐标系，更加真实地模拟实际步行情况.3.3髋臼受力的分析生理状况下，骨骼的结构和功能在很大程度上依赖于其所处的力学环境. 在髋臼骨折治疗中, 施加的力学环境, 对治疗效率、准确的愈合是至关重要的. 本研究尝试对髋臼模型进行受力分析, 将骶髂关节和耻
16、骨联合部位锁定后, 模拟步态4下髋臼的力场分布, 结果发现：在股骨头与髋臼接触部位, 最大接触力出现在髋臼的后上区域，提示在髋臼受力部位为高应力状态,皮质与松质最大受力部位较一致，皆出现在髋臼顶部附近(18 kPa, 0.36 mPa)，软骨的峰值出现在臼顶内侧区(4.1 kPa). 本研究的意义说明, 所构建的髋臼三维有限元模型可以分割, 可以进行受力的分析. 3.4标准步态下骨盆三维有限元模型建立的意义骨盆肌肉的收缩力的大小、部位及方向与髋臼的接触力对于髋关节异常情况(如畸形、手术)的模拟非常重要. 完整地了解髋臼接触力与骨盆肌肉
17、收缩力力学机制有助于进一步模拟髋关节力学行为、解剖学与手术后改变的影响，以往对髋臼进行有限元分析, 鉴于形状复杂,载荷条件复杂， 一般均对其作简化处理, 先前的模型很少有髋关节接触力的三维模拟，或是没有对附近肌肉负荷的三维模拟1-3,9. 髋关节周围的实验及理论力学模型运行时都是在缺乏肌肉收缩力的影响上得出的结果，因此分析的结果必然引起误差5，了解髋关节的接触与跨髋关节肌肉作用力对于准确模拟手术后几何条件及负载改变是非常重要的. 本研究成功构建一个既包含了肌肉有包含了髋臼接触力的髋臼三维有限元模型，真实模拟人体髋臼解剖形态，肌肉载荷及头臼作用力，而且三维有限元图像还原性好, 能从力学上真实代表
18、实物. 当然，这是全面认识髋臼生物力学改变的第一步，理想的模型将为进一步的研究提供可靠的手段和方法，也将有助于丰富髋臼的相关生物力学研究. 【参考文献】1 Kaku N, Tsumura H, Taira H, et al. Biomechanical study of load transfer of the pubic ramus due to pelvic inclination after hip joint surgery using a threedimensional finite element modelJ. J Orthop Sci, 20
19、04:264-269.2 Lalonde NM, Dansereau J, Pauget P, et al. Accessing the influence of repositioning on the pelvis 3D orientation in wheelchair users J. IEEE Trans Neural Syst Rehabil Eng, 2006,14:76-82.3 Sparks DR, Beason DP, Etheridge BS, et al. Contact pressures in the flexed hip joi
20、nt during lateral trochanteric loading J. J Orthop Res, 2005,23:359-366.4 Huiskes R. Finite element analysis of acetabular reconstruction J. Acta Orthop Stand, 1987,58:620-625.5 Pedersen DR, Brand RA. Davy DT. Pelvic muscle and acetabular contact forces during gait J. J
21、 Biomech, 1997,30:959-965.6 Dalstra M, Huiskes R, van Erning L. Development and validation of a threedimensional finite element model of the pelvic bone J. J Biomech Eng, 1995,117:272-278.7 Dalstra M, Huiskes R, Odgaard A, et al. Mechanical and textural properties of pelvic trabecular bone J.
22、J Biomech, 1993,26:523-535.8 Dostal WF. Andrews JG. A threedimensional biomechanical model of hip musculature J. J Biomech,1981,14:802-812.9 Garcia JM, Doblare M, Seral B, et al. Threedimensional finite element analysis of several internal and external pelvis fixations J. J Biomech
23、 Eng, 2000,122:516-522.10 苏佳灿，张春才，陈学强，等. 静载荷作用下骨盆三维有限元分析及其生物力学意义J. 中国临床康复，2005,9:66-67./Porganization system and working mode, the selection of a number of municipal strengthening group to build innovation and strengthen the organization of the basic level organizations advanced model.(seven) the ma
24、nual work of the Communist Youth League Organization published and League branch of manual work, to promote the use of two manuals in the citys organizations at various levels. The county committee, directly under the group (work) is under the jurisdiction of grassroots League and group (total) usin
25、g branch ratio shall not be less than 70%.Three, to further strengthen the groups leadership and team building(a) to strengthen the leagues leadership at all levels of construction. Continue to do a good job of municipal Party Committee Organization Department on the strengthening of the Communist Y
26、outh League cadres management opinions implementation. To promote the group counties (autonomous counties, cities) Commission and city directly under the group (workers) appointed to carry out the Five team building activities. Improve the League Association Department working mechanism. Conscientio
27、usly fulfill the duties of CO, combined with the city group directly under (the) Committee of the general election and the adjustment, actively jointly with the unit where the party organization department good group leadership selection with the work. Do a good job in municipal Party committee assi
28、stant committee leadership and leading cadres of the annual assessment work, adhere to and improve the assistant secretary of the Communist Youth League talk system group To weave individual conversation and collective conversation, to strengthen the committees of all levels, the Standing Committee
29、of the Standing Committee, the establishment of a sound system of central group learning, the system of investigation and study, the system of important issues and the reporting system.(two) to strengthen the work of education and training of cadres to conscientiously implement the Central Committee
30、. On the implementation of grassroots cadres training project and opinions on carrying out the mission municipal CYL Cadres training project implementation opinions, full implementation of the project of the City Youth League cadres training education. Focus on the county grassroots cadres and worke
31、rs focused on training, the new school system vocational training League cadres, for the Municipal Organization Department jointly held the third session of the Communist Youth League system training cadres in party. Focusing on the construction of new socialist countryside, strengthening village ca
32、dres and rural construction team group member of the young team, the county organizations at various levels throughout the year is expected to train 100 00 rural grassroots cadres, plans to train 1000 village secretary of the village Party branch.(three) actively promote grassroots cadres election w
33、ork. Under the unified leadership of the party organization, to strengthen grassroots organizations direct work, standardize the election work rules and procedures, in the designated candidate, open competition to democratically elected branch secretary at the same time, actively and steadily the de
34、velopment of Township, streets and other grassroots organizations in the direct election of the pilot work, on the basis of summarizing the experience and gradually expand the scope of the pilot, and gradually formed a set of measures and cadres election system.(four) to strengthen the cadres testin
35、g exercise. To study the development of XX city from 2006 to 2008 cadres testing exercise planning. To select outstanding cadres to the central mission in Beijing, Shanghai, Guangzhou and other central organs and sending work in developed areas. With the Central Committee the implementation of the w
36、estern region and ethnic minorities cadres training plan . To carry out the eighth batch of municipal organs attachment cadre management, selection, training work. The outstanding cadres to start the National Development Bank XX branch testing exercise.(five) to strengthen the group construction. Th
37、e main position to play the role of Youth League cadre education and training as the city, in accordance with the requirements of post training, further curriculum scientifically and rationally, adopt arrangement menu course, basic theory includes group work, focus, hot and difficult issues, to enha
38、nce the content and practice; to strengthen the construction of teaching staff, the integration of teachers, establish a quality teacher training team, establish and implement course evaluation system; take delivery of training to the countryside, on-site training, and increase the rural grassroots
39、cadres training efforts.Four, efforts to strengthen the work of young talent(a) to tenth XX young 54 medal in recognition of the publicity, and actively explore the XX youth service. 54 Medal of institutionalization, standardization and socialization mechanism. Give full play to the XX award in reco
40、gnition of 54 youth medal Association, Youth Award winner in the 54 chapter, investigation activities. Who won the Youth Service medal, dedication to the society to create conditions, build the stage. During the 54, named in recognition of the tenth XX young 54 medal. The association of XX editing o
41、f young talent , the exchange of information and communication platform for the XX of outstanding young talents.(two) the establishment of municipal Party committee of young talent information database. In accordance with the feasible, effective, classification management, implement step by step pri
42、nciple, the establishment of municipal Party committee of youth talent database; guiding organizations at various levels generally established the young talent database, construction of city, county (directly under the Communist Youth League), grassroots organizations three young talent information
43、database the relevant information collection system, and gradually establish the citys young people, the Communist Youth League youth talent information network, provide information platform for young talent resource development.Five, take effective measures to strengthen the mission management(a) t
44、o strengthen the mission management work. Strengthen the dues collection and management, continue to adhere to the dues collection regularly reporting system, the annual comprehensive award in recognition of the tour and the tour one vote veto system audit system. Do statistical work in the group. T
45、he group service award in recognition of the advanced units, standardization, promoting group management work institutionalized.(two) to strengthen the organization of research and information exchange efforts. Grassroots carry out research, efforts to form a number of theoretical results. Make full
46、 use of the network carrier, to explore the establishment of electronic group service system, promote the work of Communist Youth League information.Attachment 4:XX municipal Party Committee Propaganda Department of the Communist Youth League work pointsIn 2006, the Communist Youth League propaganda
47、 ideological work XX to Deng Xiaoping theory and the important thought of Three Represents as guidance, study and implement the partys sixteen and the spirit of the the fifth Plenary Session of the 16th CPC Central Committee implementation of the eight plenary session of the two committee, the citys
48、 cultural work conference, the Propaganda Department of the meeting and the the fourth Plenary Session of the 15th CPC Central Committee permanent mission spirit, closely around 11th Five-Year XX the goal of full implementation of Scientific Outlook on Development, emancipating the mind, seeking truth from facts, keep pace with the times, close to reality, close to life, close to the young, persevere grasp orientation, grasping deepening, grasping construction innovati