Longitudinal Investigation Of In Vivo Tibiofemoral Kinematics Cartilage Contact And Cartilage Composition Prior To And Following Anterior Cruciate Ligament Reconstruction

Download or read book Longitudinal Investigation of in Vivo Tibiofemoral Kinematics, Cartilage Contact, and Cartilage Composition Prior to and Following Anterior Cruciate Ligament Reconstruction written by Michael F. Vignos and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anterior cruciate ligament reconstructions (ACLR) are typically successful at restoring knee stability and returning patients to previous levels of activity. However, long-term outcomes of ACLR are concerning given that 10-15 years post-surgery>50% of patients exhibit signs of osteoarthritis. It has been theorized that the high rate of osteoarthritis in ACLR knees is partially due to residual abnormal knee mechanics that exist following surgery. Indeed, previous studies have observed abnormal kinematics and cartilage contact patterns in ACLR knees. However, there is currently limited evidence of a direct link between abnormal knee mechanics and cartilage degeneration in this population. Thus, the first primary objective of this thesis was to investigate the link between abnormal knee mechanics and biomarkers of cartilage degeneration through a combination of static, dynamic, and quantitative (i.e. mcDESPOT) magnetic resonance imaging. The second primary objective was to then assess the contribution of ACLR surgical factors to abnormal post-operative knee mechanics. We first investigated the link between mcDESPOT relaxation parameters and cartilage material properties to further validate using the mcDESPOT sequence to track changes in cartilage composition. We then investigated longitudinal changes in tibiofemoral kinematics, cartilage contact, and cartilage composition in ACLR knees. We determined that, within the medial tibial plateau, reductions in the fraction of water bound to proteoglycan were correlated to increased cartilage contact. This indicated that restoring normative knee mechanics is critical to mitigate the risk of cartilage degeneration in ACLR knees. Through the use of experimental and computational modeling methods, we then determined that non-anatomic ACL graft tunnel placement can lead to abnormal kinematics and cartilage loading during functional movement. We also observed that ACL graft stiffness and initial tension may contribute to abnormal knee mechanics. However, further work is needed to assess the relative contribution of each surgical factor to post-operative knee mechanics. Finally, we confirmed that the semi-automated algorithm used to segment articular cartilage, in this thesis, produced accurate and repeatable measures of cartilage thickness. We conclude that optimal graft tunnel placement is critical to restore normative knee mechanics, and, thus, to mitigate the risk of early osteoarthritis development in ACLR knees.