【作者】 姜海波；

【导师】 葛世荣；

【作者基本信息】 中国矿业大学 ， 机械设计及理论， 2008， 博士

【摘要】 人体下肢是人体的重要组成部分,是人体运动的主要承担者。日常生活中的意外创伤和日渐增多的关节疾病对人体的正常生活造成了损害,关节置换术是目前临床解决严重关节疾病的最终方法,但术后的失效(无菌松动、断裂、骨溶解)问题一直困扰着医学界。如何从生物力学的角度对失效的原因进行分析、对假体的设计提出相应的修改意见一直是相关学科研究的前沿课题。本文在相关方面进行了尝试,得到了一些有益的结果。本文对人体下肢系统进行了理论建模,推导出人体下肢各部分和重要关节的动力学方程表达式;利用动态捕捉系统对人体下肢进行测试,从测试结果中分析得到下肢关节在运动过程中的作用,并给出定量的结果;利用高精度医学仪器获得人体下肢的断层扫描数据,通过逆向工程原理重构了人体下肢系统模型;模拟临床手术结果,建立了髋关节置换后的人体下肢模型;利用有限元和动力学分析软件对下肢不同状态下的力学特性进行分析比较,对冲击载荷对下肢的影响进行了分析。所得结论对指导髋关节假体的设计和临床应用提供了相关的数据。通过本文的试验和理论研究,得出以下主要结论:在对人体测量学理解的基础上,利用人体下肢骨骼和关节部位的具体测量参数通过测量数据之间的关系推导出人体下肢各部位和关节的动力学公式;通过欧拉角的变换可以求出人体关节角速度和角加速度;以拉格朗日函数和哈密顿原理为基础,从能量的角度出发给出了人体下肢系统的动力学方程组。运动实验采用NDI公司生产的Optotrak_Certus动态捕捉系统,按照实验所需具体要求在健康人体和髋关节置换患者下肢相同部位和关节处进行标记点(Marker)的粘贴和定位,对其进行相同运动参数的测定,通过对采集数据的分析获得人体下肢部位和关节的运动学参数;对实验数据处理后得到髋关节置换手术对人体下肢特别是下肢关节的影响,认为髋关节置换将造成下肢力传递系统的中断,使得膝关节和踝关节以增加变形方式来弥补髋关节缺失所造成的力传递损失。对测试者进行不同足地界面的运动分析,对比两者之间的数据可以得到,对于光足和穿平底鞋两种足地界面,健康人体和置换患者在步长方面没有明显的区别;正常步态及上下楼梯步态测试结果显示穿着运动鞋比光足状态更能减小关节的变形量,降低地面冲击载荷。数据分析结果对人体下肢组织,特别是人体关节软骨在运动中的作用有了较为明确的认识,定量的分析结果对于临床和术后康复均有一定的指导作用。人体下肢系统因为其结构的复杂性,人体骨骼及关节软骨高度不规则性使得通过普通方法对其进行重建变得十分复杂。结合医学及工学的优势,本文通过对人体下肢进行CT扫描的方法获得了该部位较为精细的DICOM医学图像;经图像处理和参考人体解剖结构,利用专业软件获得了下肢骨骼的轮廓曲线,通过逆向工程原理对人体下肢进行了数字化重构,建立了包括骨骼和关节软骨在内的人体下肢系统模型;以建立的人体下肢系统为基础,将Charnley髋关节假体按照临床要求进行了手术的仿真切除和假体的模拟安装,并针对生物学固定和骨水泥固定方式分别构建了相应的模型。关节置换术是目前解决患者关节疼痛的最终也是比较有效的办法。但是关节置换后部分患者会产生关节疼痛,假体松动,运动受限等多种情况,严重的最终导致手术的失败。明确关节置换前后人体骨骼内部的力学特性的改变是了解症状产生原因的基础,而有限元又是获得所需数据的较好方法。对建立的人体下肢模型和模拟临床手术建立的髋关节置换假体模型导入有限元分析软件,对不同的部分赋予不同的材质属性,选择10节点四面体实体结构单元对其进行网格划分,在进行优化后在接触部位建立接触对。对不同的运动状态制定相应的边界条件和负载,进行模拟计算;分析结果表明置换后的股骨在应力场的分布和应力峰值方面均有改变,在置换部位应力值增加且产生应力集中现象;不同的固定方式对股骨也有影响,骨水泥固定方式可以减小应力遮挡效果,对预防骨溶融造成的假体松动具有益处。冲击载荷对置换部位的影响要大于静载,同时冲击载荷对置换体的破坏部位也由单一的股骨颈部位扩大到了小转子附近的股骨干。更多还原

【Abstract】 The most important part of human body is the lower limb,which is the main support in the human movement. There are many pathological joint mechanics osteoarthritis and accidental damage which affect the daily grind. Joint replacement is the final method to cure severe arthropathy. But the situations like asepsis loosing, prostheses break and osteolysis destroy the recuperate outlook of patient and the doctor can not solve these problems. This is the scientific research trying to find out the reasons of prostheses disabled and prostheses design based on the biomechanical theory. This paper makes some research on this aspect and gets some useful data. The first step, develop the mathematics modeling of human lower limb and calculate the kinematics parameters. Measure the human lower limb gait cycle data by NDI’s Optotrak Certus system. It is important to get the DICOM images in order to create mechanical model of human lower limb. The lower limb system model should be developped by inverse engineer theory based on images data. The clinic total hip replacement (THR) is created with charnly prostheses. All the models opened in the finite element software and get the mechanical charactertics data. The analysis conclusion has the useful results directing the prostheses design and clinic operation.Some conclusions were obtained according the experimental and theoretical researching, as below:The displacement function can be got based on the anthropometry through 15 marks paste on the connor body. The angle velocity and angle acceleration are obtained through Euler angle transformation. Human lower limb dynamic equations can be got through Lagrange and Hamilton theory.The Optotrak Certus system that made in NDI company is used in motion experiment. The conner consists of healthy body and implanted body. Markers should be pasted on the human body in order to get the gait data under the same criterion. During the gait cycle, the conners do the same action with sneaker and bare foot. It has been shown that implanted patient has the different gait curve with healthy body and the joint deformation magnitude bigger than healthy body’s. The conner with sneaker has much less joint deformation magnitude than bare one. It has been known that the joint cartilage has the important function in decreasing the impact loading.Create the model that can be used to calculate the stress and deformation is the key step. The human lower limb anatomy data can be got through CT scan. The human lower limb skeleton map will create from DICOM image data by professional software based on inverse engineering theory. The model consists of lower limb skeleton and joint cartilage. The Charnley hip prosthesis is assemble with femur under simulation operation.Joint replacement is a useful operation to avoid ache from patient for the severity arthropathy. But joint ache, asepsis loosing, prostheses break and osteolysis could appear after operation that can induce the operation destruction. The stress distribution and deformation magnitude of replacement part are the important data to understand the reasons causing the operation destruction. The finite element method (FEM) is the effective tool to get this information. Open the models in the FEM software and mesh the grid with 10 nodes four areas solid element. Create the contact pairs in joint, set the boundary condition and loading based on different motion. Some results as follow are shown after finite element calculation. The stress assemble in implanted part and stress value increase after operation; Bone cement fixation type has lower stress value than biology fixation type that is wonderful to prevent artificial joint loosing caused by osteolysis; Impact loading has more affection than static loading and destroy position comprise femur neck and shaft of femur near lesser trochanter.更多还原