Knee joint mechanics assessments

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The loss of integrity of the anterior cruciate ligament (ACL) in the knee can also alter joint stability and dynamics and lead to higher risk and incidence of osteoarthritis (OA). However, direct non-invasive in-vivo quantification of joint contact mechanics within the joint structures has been limited. Consequently, characteristics of normal healthy joint mechanics, and those leading to pathological conditions are not well established. The overall research goals are to understand relations amongst joint mechanics, joint health status, joint injury and repair mechanisms, and the development of degenerative changes associated with ligament injury and repair. Three main hypotheses will be tested: (H1) Differences in ACL integrity and joint tissue condition are detected with in-vivo knee joint stiffness measures and ACL laxity predictions, (H2) Cartilage force-deformation (FD) characteristics are correlated to proteoglycan (PG) concentrations using integrated MRI and joint loading techniques, and (H3) Abnormal dynamic joint stability is correlated with alterations in vivo joint stiffness, cartilage FD characteristics and PG concentrations. Knee joint laxity, and cartilage force-deformation characteristics will be imaged and quantified for 4 in-vivo groups: healthy, congenital joint laxity, ACL deficient with early degenerative changes and ACL deficient with severe OA, under various knee flexion and loading conditions. Using novel joint laxity device, MR imaging, image registration techniques, and modeling, normative ranges for joint and ACL laxity tissue characteristics will be developed. In-vivo cartilage deformation characteristics will be evaluated and correlated with cartilage composition (proteoglycan concentration) using innovative imaging techniques and loading devices. Joint dynamic stability will be assessed for each group using 3D motion analysis, and correlated to tissue characteristics. This research develops the foundations for a joint characterization toolkit, and provides a unique and novel advance with potential impact for clinical treatment evaluations.