Measurement of joint mechanics with novel imaging methods

最新进展：在过去的六年里，我和我的HQP已经1）开发了一种基于对比增强计算机断层扫描（CECT）的无损方法来映射完整膝盖和拇指的软骨硬度; 2）开发并应用工具来预测膝盖软骨下骨的载荷传递;和3）开发并评估了一种用于测量髋关节软骨应变的新方法，该方法不需要破坏任何髋关节结构。 目的：该研究计划的长期目标是开发在生理条件下评估关节力学的方法，并应用这些方法来了解关节力学的自然变化以及单个关节结构如何有助于整体关节力学功能。 在这个项目中，我们的短期目标包括：目标1：确定在生理负荷下解剖变异对髋关节标本软骨应变的影响以及与骨和软骨刚度的关系; 目标二：确定髋关节软骨硬度和CECT衰减之间的关系;目标3：确定髋关节软骨下骨CT衰减和硬度之间的联系。 方法：在加拿大光源同步辐射加速器上对20例尸体髋关节标本进行成像。 将注射阳离子造影剂（CA 4+）并使其分布在软骨内。 将使用加载装置在三种载荷/位置组合下对样本进行成像。 从软骨厚度的变化可以发现软骨应变。 然后将样本分离，并将髋关节表面分成切片。 将使用Mach 1压痕测试系统评估关节表面的肱骨和软骨下骨刚度。 将使用校准体模根据基线同步加速器图像确定软骨下骨密度图。 将确定软骨中CECT衰减与软骨硬度之间的关联，以及软骨下骨矿物质密度与硬度之间的关联。 将开发、验证有限元模型，并用于预测软骨下骨的应力/应变。 HQP： 这项研究将为4名MASc，1名博士和5名本科生的多元化团队提供生物力学，成像和图像处理方面的出色培训。 培训环境和机会将产生成功的科学家，企业家和工程师的行业和学术环境，因为我们在过去六年。 影响： 这项研究计划将有助于提高对正常髋关节生物力学的理解，并为非破坏性评估髋关节生物力学提供新的工具。

Recent Progress: In the last six years, my HQP and I have 1) developed a nondestructive approach for mapping cartilage stiffness in the intact knee and thumb based on contrast-enhanced computed tomography (CECT); 2) developed and applied tools to predict load transmission through the subchondral bone of the knee; and 3) developed and assessed a new method for measuring hip cartilage strain that does not require disruption of any hip structures. Objectives: The long-term objectives of this program of research are to develop methods to assess joint mechanics under physiological conditions and to apply these methods to understand natural variation in joint mechanics and how the individual joint structures contribute to overall joint mechanical function. Within this program, our short-term objectives include: Aim 1: Determine the effect of anatomical variation on cartilage strain in hip specimens at physiological loads and associations with bone and cartilage stiffness; Aim 2: Determine the relationship between stiffness and CECT attenuation in hip cartilage; and Aim 3: Determine links between CT attenuation and stiffness of hip subchondral bone. Methods: We will image 20 cadaver hip specimens in the Canadian Light Source synchrotron. A cationic contrast agent (CA4+) will be injected and allowed to distribute within the cartilage. Specimens will be imaged at three load/position combinations using a loading rig. Cartilage strain will be found from the change in cartilage thickness. Specimens will then be disarticulated and hip joint surfaces will be divided into sections. Cartilage and subchondral bone stiffness will be assessed across the joint surfaces using a Mach 1 indentation testing system. Subchondral bone density maps will be determined from baseline synchrotron images using a calibrated phantom. The association between CECT attenuation in cartilage and cartilage stiffness, and between subchondral bone mineral density and stiffness will be determined. Finite element models will be developed, validated and used to predict stress/strain in the subchondral bone. HQP: This study will provide excellent training in biomechanics, imaging and image processing to a diverse group of 4 MASc, 1 PhD and 5 Undergraduate students. The training environment and opportunities will produce successful scientists, entrepeneurs and engineers for industry and academic environments as we have in the past six years. Impact: This program of research will contribute an enhanced understanding of normal hip joint biomechanics and new tools for assessing hip biomechanics nondestructively.