Measurement of joint mechanics with novel imaging methods

最新进展：在过去六年中，我和我的HQP 1)开发了一种基于对比增强计算机断层扫描(CECT)的无损方法来绘制完整膝关节和拇指的软骨硬度图；2)开发并应用了预测载荷通过膝关节软骨下骨传递的工具；以及3)开发和评估了一种不需要破坏任何髋关节结构的测量髋关节软骨应变的新方法。 目的：这项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异以及单个关节结构如何对整体关节力学功能做出贡献。在这项计划中，我们的短期目标包括：目标1：确定生理负荷下解剖变异对髋关节标本软骨应变的影响及其与骨和软骨硬度的关系；目标2：确定髋关节软骨硬度与CECT衰减之间的关系；以及目标3：确定CT衰减与髋关节软骨下骨硬度之间的联系。 方法：我们将在加拿大光源同步加速器上对20具身体髋关节标本进行成像。将注射阳离子造影剂(CA4)，并允许其分布在软骨内。将使用加载装置在三种载荷/位置组合下对试件进行成像。从软骨厚度的变化中会发现软骨拉伤。然后，标本将被分离，髋关节表面将被分成几个部分。软骨和软骨下骨硬度将使用1马赫压痕测试系统在关节表面进行评估。软骨下骨密度图将使用校准的体模从基线同步辐射图像中确定。将确定软骨中CECT衰减与软骨硬度之间的关系，以及软骨下骨密度与软骨硬度之间的关系。有限元模型将被开发、验证并用于预测软骨下骨中的应力/应变。 HQP：这项研究将为4名硕士、1名博士和5名本科生提供生物力学、成像和图像处理方面的出色培训。培训环境和机会将为工业和学术环境培养成功的科学家、企业家和工程师，就像我们在过去六年中所做的那样。 影响：这项研究计划将有助于加深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.