Micro-Mechanical Characterization of Damage in Ligaments

韧带损伤的微观机械特征

• 批准号: 0932024
• 负责人: Raffaella De Vita
• 金额: $ 30.02万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0932024&HistoricalAwards=false
• 关键词: Micro; Mechanical; Characterization; Damage; Ligaments

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."0932024De VitaSprains of the knee ligaments are among the most common orthopedic injuries. They usually occur when the knee is forced beyond its normal range of motion, such as in a fall. They also happen when the knee experiences an impact, such as in a car accident or during a football tackle. These injuries can consist of a slight over-stretch, a partial tear, or a complete disruption of the ligaments. While many investigators in biomechanics have focused on quantifying the material properties of ligaments, such as tangent modulus, tensile strength, and ultimate strain, little is know of their response to mechanical stimuli that lead to partial and complete failure. In particular, studies are needed to clarify the micro-structural changes associated with partial and complete tears. For the first time, constitutive relationships that explain the role of microstructure in the damage evolution process of ligaments will be developed. These models will be derived by integrating molecular models that provide information about collagen cross-linking and collagen molecular damage with structural continuum models. The structural models will be formulated by taking into account the components of the ligamentous tissues, their geometrical arrangement, and their interactions. They will describe the typical anisotropy, nonlinearity, and inelasticity exhibited by ligamentous tissue. Together with the theoretical study, mechanical and microscopic experiments will be performed to quantify the effect of collagen intermolecular cross-linking on the failure of ligaments. Toward this end, knee ligaments harvested from two groups of animals, one fed with a normal diet and another fed with a lathyritic diet, will be subjected to different sub-failure stretches along their physiological direction. Ligaments will be examined for microscopic structural damage, and molecular fragmentation of collagen _brils will be assessed to determine how ligament failure occurs on a molecular level. This information will, in turn, be correlated to the structural models developed based upon the mechanical data. Together, these three approaches will culminate in a more complete understanding of the structure/function relationship of the components of ligament.Intellectual Merit. The successful completion of the proposed project requires a combined knowledge of theoretical and experimental mechanics of biological systems as well as molecular biology. The PIs will combine their expertise in continuum mechanics (R. De Vita), molecular modeling (J. W. Freeman), experimental mechanics (J. G. Barrett, R. De Vita and J. W. Freeman) and molecular biology (J. G. Barrett) to formulate novel models that together with mechanical and microscopic experiments will elucidate the relationship between damage development and material composition of ligaments. This research program will have a signifcant impact in the area of engineering materials for replacement grafts and biological scaffolds by offering a knowledge of mechanical and structural properties to target in developing replacements for ligaments. The results can also guide the design of braces or stretching routines to limit ligament strain so as prevent damage during stressful activities. Because ligaments possess a very well organized structure and a relatively simple composition, the research findings will contribute to understanding the failure mechanism of more complex biological soft tissues such as, for example, skin and arteries.Broader Impacts. Undergraduate and graduate students will be engaged in the theoretical, numerical, and experimental components of the research project. The PIs will work with the Bioin-formatics and Bioengineering Summer Institute program and the College Bound program to attract and retain underrepresented groups to science and engineering. Research findings will be incorporated into current courses that are offered in the undergraduate, graduate and professional curricula. The results of the research will be presented at national and international conferences and published in peer-reviewed journals.

该奖项根据 2009 年《美国复苏和再投资法案》（公法 111-5）提供资金。“0932024De Vita 膝关节韧带扭伤是最常见的骨科损伤之一。它们通常发生在膝盖被迫超出其正常运动范围时，例如跌倒时。它们也会发生在膝盖受到冲击时，例如在车祸或足球铲球过程中。这些损伤可能包括 轻微过度拉伸、部分撕裂或韧带完全断裂。虽然生物力学领域的许多研究人员都专注于量化韧带的材料特性，例如切线模量、拉伸强度和极限应变，但对其对导致部分和完全失效的机械刺激的反应知之甚少。特别是，需要研究来阐明与部分和完全撕裂相关的微观结构变化。 对于第一个 随着时间的推移，解释微观结构在韧带损伤演化过程中作用的本构关系将会得到发展。这些模型将通过将提供有关胶原蛋白交联和胶原蛋白分子损伤信息的分子模型与结构连续体模型相结合而衍生。结构模型将通过考虑韧带组织的组成、它们的几何排列及其相互作用来制定。他们将描述典型的 韧带组织表现出各向异性、非线性和无弹性。与理论研究一起，将进行机械和显微实验，以量化胶原蛋白分子间交联对韧带失效的影响。为此，从两组动物身上采集膝关节韧带，一组用正常饮食喂养，另一组用山豆素饮食喂养，将接受不同的处理。 子衰竭沿着其生理方向延伸。 将检查韧带的微观结构损伤，并评估胶原蛋白 _brils 的分子碎片，以确定韧带失效如何在分子水平上发生。反过来，该信息将与基于机械数据开发的结构模型相关联。总之，这三种方法将最终使人们更全面地理解各组成部分的结构/功能关系。 韧带。智力优点。该项目的成功完成需要生物系统理论和实验力学以及分子生物学的综合知识。 PI 将结合他们在连续介质力学 (R. De Vita)、分子建模 (J. W. Freeman)、实验力学 (J. G. Barrett、R. De Vita 和 J. W. Freeman) 和分子生物学 (J. G. Barrett) 方面的专业知识 制定新颖的模型，结合机械和微观实验，阐明损伤发展与韧带材料成分之间的关系。该研究计划将通过提供机械和结构特性的知识来开发韧带替代品，从而对替代移植物和生物支架的工程材料领域产生重大影响。结果还可以指导支架或拉伸程序的设计，以限制韧带拉伤，从而 防止在有压力的活动中受到伤害。由于韧带具有组织良好的结构和相对简单的组成，因此研究结果将有助于了解更复杂的生物软组织（例如皮肤和动脉）的失效机制。影响更广泛。本科生和研究生将参与研究项目的理论、数值和实验部分。 PI 将与生物信息学和 生物工程暑期学院计划和大学绑定计划旨在吸引和留住代表性不足的群体进入科学和工程领域。研究结果将纳入本科生、研究生和专业课程中提供的当前课程。研究结果将在国内和国际会议上展示，并在同行评审期刊上发表。