生物力学学术动态

为了促进生物力学这门新兴边缘学科的发展,活跃学术空气,上海市力学会生物力学专业组制订了1981年生物学术活动计划,其主要内容有:人工假体、骼骨、髋关节、膝关节的生物力学分析,骨骼及器官的材料性质的研究,骨折的愈合及中西医结合治疗,人体软组织     

人工髋、膝关节磨损测试标准及模拟试验机研究进展

髋膝关节植入物假体在体内发生摩擦磨损进而造成骨溶解、无菌松动是导致其失效的重要原因之一. 人工髋膝关节磨损试验是对假体材料、设计和加工进行评价的重要形式. 天然髋膝关节承受的运动和载荷十分复杂，研究天然关节在各种行为下的受力和运动范围，并利用专门的髋膝关节模拟器来进行试验和评价，有助于人工关节的设计和耐磨关节材料的发展. 本文中整理了天然髋膝关节的运动范围及载荷，对比了人工髋膝关节假体磨损的国内外标准，总结了主流髋膝关节模拟试验机的结构及主要技术参数，为我国关节行业的研究者提供参考.      

植入假体后的股骨建模及有限元分析

目的:本研究建立股骨端髋关节置换有限元模型,并进行了静力学模拟计算,为寻求假体的个体化和假体加长、加粗等设计起到指导作用。方法:运用逆向工程与有限元的基本概念和理论,采用ANSYS V6.1对股骨进行静应力的计算。结果:通过完全适应髓腔假体和股骨的共同受力分析,发现股骨受力的主要部位在股骨距。结论:该模型符合国人的股骨上端生物力学特性,是一个较好的髋关节置换有限元模型,为进一步模拟翻修关节的临床实际奠定基础。     

人工膝关节模拟试验机及其生物摩擦学性能评价研究进展

人工膝关节生物摩擦学模拟试验是在设计和制造阶段评价人工膝关节假体的主要方法.本文介绍了球面接触型、假体力和运动直接控制型及膝关节肌肉力重建型3类人工膝关节模拟试验机及其对应生物摩擦学研究现状,讨论了3类人工膝关节生物摩擦学试验的要求和特点,详细说明了现有人工膝关节生物摩擦学试验和测试标准,指出今后还需增加动物活体试验方式,扩大模拟人体运动测量范围,并应加强多因素同时作用下人工膝关节磨损机理研究,制定统一的人工膝关节生物摩擦学试验标准.     

运动生物力学发展现状及挑战

狭义的运动生物力学特指人体运动中的生物力学,主要解决竞技体育领域中如何提高运动成绩和减少运动损伤的问题.随着相关学科的融合和发展,当前运动生物力学的研究已扩展到与人类运动相关的生物学、医学、力学等学科领域.近年来,智能测试、大数据分析、人工智能等技术快速发展,对运动生物力学实验、仿真方法产生了重要的影响,在不断拓展和深化着该学科的研究内容和方向的同时,也对运动生物力学发展提出了新的挑战.本文综述了近年来运动生物力学领域的研究现状,并指出了相关研究方向的关键问题及发展趋势:在理论建模和模拟仿真计算方面,肌肉本构理论及肌肉力计算准确性是重点和难点;实验测试的新技术在竞技体育运动项目中的应用研究中扮演重要角色,其中基于深度学习的人体关键点检测算法在解决竞技体育的非接触测量方面有突破性进展;对于骨、韧带、软骨、肌肉等组织的宏观损伤机制认识不断清晰,但对于其早期损伤预测以及跨尺度损伤发生机制的研究仍有待深入;智能可穿戴装备、人工智能等新技术开始应用于运动生物力学研究及实践,成为目前运动生物力学领域最具活力的研究方向之一.本文的综述表明当前运动生物力学研究越来越向智能化、个体化、定量化发展,并正在...     

人工椎间盘生物摩擦学研究进展:脊柱模拟试验机方法

人工椎间盘生物摩擦学性能评估有多种研究方法,其中使用脊柱模拟试验机是评估椎间盘假体中长期磨损性能的主要手段.本文整理了近年来使用脊柱模拟试验机进行椎间盘假体磨损性能评估的研究文献,介绍了现有脊柱模拟试验机种类和研究方法以及相关试验标准;分析了近年来针对影响假体磨损性能主要因素(假体结构设计、关节材料、材料表面处理、载荷/运动/频率、润滑液、磨损时间等)所取得的研究进展;综述了主要颈腰椎人工椎间盘假体的磨损性能.     

骨与膝关节生物力学行为研究

膝关节的运动损伤和累积疲劳损伤引起的骨性关节炎非常普遍,膝关节生物力学行为的研究在探求膝关节疾病的病因和发病机制、治疗和预防关节病方面起到重要作用,同时也有助于膝关节康复与矫形支具的设计。对于膝关节生物力学的研究可以采用实验法和有限元法,近年来有限元方法得到广泛的应用,而其进一步发展还有赖于关节骨及其组织细观结构与宏观力学性能间关系的研究。     

维生素 E型人工膝关节在ISO标准步态与上楼梯运动下的磨损情况对比

为研究人工膝关节假体在ISO标准步态与上楼梯运动负载下的摩擦磨损情况,通过对日常活动频次及动力学和运动学的研究与分析,基于人工膝关节磨损试验机,以新型Vitamin E型人工膝关节为对象进行500万次标准步态磨损测试加200万次上楼梯运动磨损测试. 结果表明正常步态阶段的磨损率为4.34 mg/mc,上楼梯运动阶段的磨损率为5.95 mg/mc. 上楼梯运动相比标准步态对半月板衬垫的磨损量造成更大的影响,半月板衬垫表面形貌相较标准步态磨损后表面形貌也发生了显著变化,出现了条纹图案和局部凹陷,这种表面形貌结果更接近于临床半月板衬垫取出物的表面形貌,目前对于人工膝关节假体的标准磨损测试方式不够全面,需要进一步改进整个测试的方案才能更好地体现体外磨损测试的意义.      

骨组织生长重建的力学生物学机制研究进展

生物力学已被证实是骨组织生长、重建及成形当中一个十分重要的因素. 骨组织的损 伤修复过程本质上是细胞的生物学过程和应力作用下的生长过程. 这虽然肯定了生物力学在 骨组织生长、重建过程中的重要地位, 但是, 人们对生物力学因素如何诱导骨生长、 重建的力学生物学机制仍不甚了解. 而骨组织工程需要更为科学完善的细胞生物学机制来研究和探 索骨组织的构建过程. 本文概述了国内外生物力学与骨组织生长重建的宏微观理论, 主要讨 论了骨组织结构及功能形成过程中的力学生物学相关问题.     

人工髋关节假体生物力学与生物摩擦学性能评价方法研究进展

人工髋关节假体性能评价关系到其在体内的服役情况，髋关节假体在体内承受的负荷、运动以及体液环境等非常复杂，在体外构建复杂环境用以研究在体内环境下关节假体的服役行为，有助于减少人工关节假体失效和提高患者满意度.本文中通过文献调研的方式，详细阐述了关于髋关节假体的相关评价标准和学者们的评价研究方法，指出了现有评价方法存在的局限性，并提出改善思路.对于关节假体所使用材料的评价，国内外相关机构制定了一系列标准程序，用以评估其力学和摩擦学特征，但对于多孔材料的性能评价仍需进一步研究.对于关节部件的性能评价已形成相关测试标准，但存在评价过于简化等问题，有部分评价方法还处于实验室研究阶段.对于关节假体生物力学性能和运动功能评价，均处于试验室研究阶段.其中，部分性能/功能评价研究较多，但研究中所采用的运动和加载条件与体内真实环境存在差异的问题仍需要进一步解决.建立系统性和层次性的髋关节假体评价体系，施加可近似等效在体服役的环境，平衡各影响因素之间的相互作用对骨科植入物的临床前评估发展具有重要的意义.     

关于人膝关节生物力学模型的研究现状

建立人膝关节模型是生物力学研究领域中最具挑战性的课题之一．本文对人膝关节生物力学模型的研究现状予以简单的评估和综述．结果显示：目前用于研究人膝关节的大部分模型,均属静力或准静力模型;仅建立了极少的人膝关节解剖基生物动力模型,且均属二维动力模型．因此,建立一个三维真实人膝关节生物动力模型是目前迫在眉睫的工作     

一个三维人膝关节弹性咬合的生物力学模型

基于人膝关节的解剖特征,在文献和试验的基础上,对膝关节解剖结构作了适当的简化,从而建立了一个完整的三维人膝关节弹性咬合的生物力学模型。     

正常和早期膝骨关节炎的软骨生物力学研究

膝骨关节炎是导致膝关节疼痛和慢性残疾的一种常见的关节疾病. 膝关节的软骨生物力学是评价膝骨关节炎程度的重要指标. 然而, 早期膝骨关节炎的软骨生物力学依然有待研究, 正常、内侧和内外侧早期膝骨关节炎的软骨生物力学差异尚不清楚. 本文基于固?液双相纤维增强的软骨有限元建模方法, 分别建立了正常膝关节模型、内侧早期膝骨关节炎模型和内外侧早期膝骨关节炎模型, 在步态周期中最大载荷时刻和最大屈曲角度时刻下分别对比分析了正常、内侧和内外侧早期膝骨关节炎3种情况下的软骨生物力学差异. 结果表明, 与正常膝关节相比, 内侧早期膝骨关节炎模型的内侧软骨的流体压力减少, 固相等效应力减少以及应变增大; 外侧软骨的结果基本没有差异. 然而, 内外侧早期膝骨关节炎模型的内外侧软骨的流体压力都减少, 固相等效应力都减少以及应变都增大. 早期膝骨关节炎中退变软骨的属性变化会导致软骨的承载能力下降以及变形增大, 从而增加软骨进一步退变的风险. 本文提出的基于双相纤维增强软骨模型的膝关节有限元模型有效预测了正常和关节炎情况下的软骨生物力学差异, 该模型也可以推广应用于髋、踝和脊柱等其他关节生物力学的研究.      

A two-phase computational biomechanics model for successful rehabilitation after hip and knee surgery

Nonlinear Dynamics - We propose a two-phase computational biomechanical model for a successful rehabilitation after hip and/or knee replacement surgery. The first phase, conducted before the...     

DETERMINATION OF QUADRICEPS FORCES IN SQUAT AND ITS APPLICATION IN CONTACT PRESSURE ANALYSIS OF KNEE JOINT

While the quadriceps muscles of human body are quite important to the daily activities of knee joints,the determination of quadriceps forces poses significant challenges since it cannot be measured in ...     

A new nonlinear multibody/finite element formulation for knee joint ligaments

The focus of this investigation is to study the mechanics of the human knee using a new method that integrates multibody system and large deformation finite element algorithms. The major bones in the knee joint consisting of the femur, tibia, and fibula are modeled as rigid bodies. The ligaments structures are modeled using the large displacement finite element absolute nodal coordinate formulation (ANCF) with an implementation of a Neo-Hookean constitutive model that allows for large change in the configuration as experienced in knee flexion, extension, and rotation. The Neo-Hookean strain energy function used in this study takes into consideration the near incompressibility of the ligaments. The ANCF is used in the formulation of the algebraic equations that define the ligament/bone rigid connection. A unique feature of the ANCF model developed in this investigation is that it captures the deformation of the ligament cross section using structural finite elements such as beams. At the ligament/bone insertion site, the ANCF is used to define a fully constrained joint. This model will reflect the fact that the geometry, placement and attachment of the two collateral ligaments (the LCL and MCL), are significantly different from what has been used in most knee models developed in previous investigations. The approach described in this paper will provide a more realistic model of the knee and thus more applicable to future research studies on ligaments, muscles and soft tissues (LMST). Current finite element models are limited due to simplified assumptions for the spatial and time dependent material properties inherent in the anisotropic and anatomic constraints associated with joint stability, and the static conditions inherent in the analysis. The ANCF analysis is not limited to static conditions and results in a fully dynamic model that accounts for the distributed inertia and elasticity of the ligaments. The results obtained in this investigation show that the ANCF finite elements can be an effective tool for modeling very flexible structures like ligaments subjected to large flexion and extension. In the future, the more realistic ANCF models could assist in examining the mechanics of the knee to study knee injuries and possible prevention means, as well as an improved understanding of the role of each individual ligament in the diagnosis and assessment of disease states, aging and potential therapies.     

钢结构斜隅支撑体系弹塑性计算方法研究

钢结构斜隅支撑体系是一种新型结构体系。与一般的纯框架和中心支撑框架体系不同，该体系综合了延性好、抗侧移刚度大的特点。在遭遇罕遇地震荷载作用下，结构通过隅撑的弯曲屈服耗能，保证其他主要构件不受损伤，使得震后修复较为容易且费用较低。但此类结构复杂的非线性分析在一定程度上阻碍了其推广与应用。本文经过力学分析推导，结合有限元方法和塑性铰理论提出了一种简化计算分析模型。采用该模型，整个求解过程仅涉及少量的线性计算，不涉及迭代，可以有效地简化斜隅支撑结构在侧向荷载作用下的弹塑性受力分析。算例表明，该计算方法建模合理，运算速度快。同时，计算结果稳定、可靠，与有限元分析程序得出的结果具有较好的一致性。     

A multi-body optimization framework with a knee kinematic model including articular contacts and ligaments

Multi-body optimization is one of the methods proposed to reduce the errors due to soft-tissue artifact in gait analysis based on skin markers. This method uses a multi-body kinematic model driven by the marker trajectories. The kinematic models developed so far for the knee joint include a lower pair (such as a hinge or a spherical joint) or more anatomical and physiological representations including articular contacts and the main ligaments. This latter method allows a better representation of the joint constraints of a subject, potentially improving the kinematic and the subsequent static and dynamic analyses, but model definition and mathematical implementation can be more complicated. This study presents a mathematical framework to implement a kinematic model of the knee featuring articular contacts and ligaments in the multi-body optimization. Two penalty-based methods (minimized and prescribed ligament length variations) consider deformable ligaments and are compared to a further method (zero ligament length variation) featuring isometric ligaments. The multi-body optimization is performed on one gait cycle for five asymptomatic male subjects by means of a lower limb model including the foot, shank, thigh and pelvis. The mean knee kinematics, ligament lengthening and contact point positions are compared over the three methods. The results are also consistent with results from the literature obtained by bone pins or biplanar fluoroscopy. Finally, a sensitivity analysis is performed to evaluate how the joint kinematics is affected by the weights used in the penalty-based methods. The approach is purely kinematic, since the penalty-based framework does not require the solution of the joint static or dynamic analyses and makes it possible to consider ligament deformations without the definition of ligament stiffness that generally cannot be identified through in vivo measurements. Nevertheless, as far as a knee kinematic model is concerned, particularly in musculoskeletal modeling, this approach appears to be a good compromise between standard non-physiological kinematic models and complex deformable dynamic models.     

Patient-specific finite element analysis of popliteal stenting

Nitinol self-expanding stents are used for the endovascular management of peripheral artery diseases of the popliteal artery, which is located behind the knee joint. Unfortunately, the complex kinematics of the artery during the leg flexion leads to severe loading conditions, favouring the mechanical failure of the stent, calling for a specific biomechanical analysis. For this reason, in the present study we reconstruct by medical image analysis the patient-specific popliteal kinematics during leg flexion, which is subsequently exploited to compute the mechanical response of a stent model, virtually implanted in the artery by structural finite element analysis (FEA). The medical image analysis indicates a non-uniform configuration change of the artery during the leg flexion, leading to an increase of the vessel curvature above the knee. The computed mechanical response of the stent reflects the non-uniform configuration change of the artery as after the flexion the average stress is higher in the part of the stent located above the knee. Although the proposed analysis is limited to a case-study, it shows the capability of patient-specific FEA simulations to compute the mechanical response of a stent model subjected to the complex and severe loading conditions of the popliteal artery during leg flexion.