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，用于绘制完整膝盖和拇指的软骨硬度； 2）开发并应用工具来预测通过膝关节软骨下骨的负载传递； 3) 开发并评估了一种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。 目标：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各个关节结构如何对整体关节机械功能做出贡献。 在该计划中，我们的短期目标包括： 目标 1：确定解剖变化对生理负荷下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 2：确定髋关节软骨硬度与 CECT 衰减之间的关系；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中对 20 具尸体髋部标本进行成像。 将注射阳离子造影剂 (CA4) 并使其分布在软骨内。 将使用加载装置在三种负载/位置组合下对样本进行成像。 从软骨厚度的变化可以看出软骨应变。 然后，标本将被解开，髋关节表面将被分成多个部分。 将使用马赫 1 压痕测试系统评估关节表面的软骨和软骨下骨硬度。 软骨下骨密度图将使用校准模型根据基线同步加速器图像确定。 将确定软骨中 CECT 衰减与软骨硬度之间以及软骨下骨矿物质密度与硬度之间的关联。 将开发、验证并使用有限元模型来预测软骨下骨中的应力/应变。 HQP：这项研究将为由 4 名硕士生、1 名博士生和 5 名本科生组成的多元化群体提供生物力学、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，就像我们过去六年一样。 影响：该研究计划将有助于加深对正常髋关节生物力学的理解，并提供无损评估髋关节生物力学的新工具。

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.