Measurement of joint mechanics with novel imaging methods

点击翻译按钮获取中文摘要

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.