Investigation Of Anterior Cruciate Ligament And Medial Collateral Ligament Biomechanics During 6 Degree Of Freedom Robotically Simulated Athletic Tasks

Download or read book Investigation of Anterior Cruciate Ligament and Medial Collateral Ligament Biomechanics During 6-degree-of-freedom, Robotically-simulated Athletic Tasks written by Nathaniel A. Bates and published by . This book was released on 2014 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: The anterior cruciate ligament (ACL) passively stabilizes the knee and plays a complex role in joint restraint during tibiofemoral articulations. ACL injuries are traumatic events that have short and long term consequences for affected athletes. Unfortunately, treatment through ACL reconstruction fails to completely restore native knee biomechanics or reduce the early onset of osteoarthritis following rupture. Therefore, the best treatment for ACL injuries may be to prevent their occurrence. To enhance ACL injury prevention, investigators must enhance the understanding of underlying, intra-articular mechanics that precede rupture. Use of robotic technology has allowed investigators to better examine native knee biomechanics during simulated clinical tests and gait. However, ACL injuries do not frequently occur during gait, but during athletic tasks that involve rapid deceleration or change in direction. The objective of these studies was to utilize in vivo recorded, three-dimensional kinematics to derive six-degree-of-freedom robotic simulations of athletic tasks that can assess native tibiofemoral mechanics in scenarios related to ACL injury. The created model successfully articulated cadaveric lower extremities though drop vertical jump and sidestep cutting tasks without specimen damage. The ACL serves as a secondary restraint to knee abduction and internal tibial rotation and, therefore, can be loaded through multiple rotational perturbations. Investigators dispute over which planes of motion contribute most significantly to ACL injury. The presented model found that combined knee rotations evoked the greatest ACL strains, but isolated knee abduction accounted for the majority of this loading. The model was then utilized to define how and why concomitant medial collateral ligament (MCL) injuries only occur in 30% of ACL ruptures, despite the shared mechanism of abduction loading for both ligaments. It was observed that during controlled athletic tasks the MCL was generally less loaded and strained and, therefore, less exposed to injury risk than the ACL. Finally, ACL injuries are gender-specific events with higher incidence rates in female athletes. Mechanical assessment of sex-specific kinematic simulations of athletic tasks revealed that neither joint loads nor ligament strains exhibited increased injury risk in females. This therefore supported that the conditions simulated in these studies indicated non-contact ACL injuries may be "black swan" events, a product of unanticipated and abnormal joint loading generated from an unexpected loss of neuromuscular control. Clinically, the current investigations indicated that preventive measures should continue to focus on reduction of knee abduction in order to lower ACL injury incidence. Greater baseline loading within the ACL than the MCL during athletic tasks supported how ACL rupture occurs with limited concomitant MCL injuries. The absence of observed gender differences, relative to ACL protection, indicated gender-specific training and rehabilitation protocols should be unnecessary as structural loading during regulated athletic tasks is comparable. Findings from these investigations advance the understanding of intra-articular knee biomechanics and can be incorporated into efforts to prevent ACL injuries. Future considerations should focus on further development of subject-specific simulation models that address additional sources of joint perturbation as well as the application of present models to the evaluation and efficacious improvement of current repair and reconstruction methods.