Characterizing The Ovine Stifle Model As A Preclinical Biomechanical Surrogate For The Human Knee

Download or read book Characterizing the Ovine Stifle Model as a Preclinical Biomechanical Surrogate for the Human Knee written by Safa T. Herfat and published by . This book was released on 2011 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: The long term goal of this research is to protect knee joint surfaces after knee surgery, thereby reducing the incidence of osteoarthritis. The objective of this dissertation was to determine if the ovine stifle joint is a suitable preclinical biomechanical model for the human knee. Using a 6 degree of freedom (DOF) robot, we applied simulated human and ovine in vivo motions to human knee and ovine stifle joints to measure the 3D joint and ACL kinetics. In addition, we investigated the biomechanical contributions of the other major knee structures. The in vivo studies were designed to determine the effect of surgically implanting motion and force sensors on ovine gait by monitoring the vertical ground reaction forces (VGRFs). Following surgery, we simultaneously measured VGRFs, knee kinematics, and the output from an arthroscopically implantable force probe (AIFP) which was implanted into the ACL. The kinematics were then simulated and applied to the operated joints, while measuring the 3D joint forces and moments. The AIFP output was used to validate the reproduced motions. Finally, we determined the effect of perturbing a simulated in vivo motion on 3D joint and ACL kinetics, which allowed us to investigate the potential effect of motion recording and reproduction errors on force and moment measurements. Applying simulated human and ovine in vivo motions to human knee and ovine stifle joints resulted in few significant kinetic differences between the human and ovine intact joints and ACLs. For a simulated 6 DOF ovine motion applied to the ovine stifle joint, the bony interaction and medial meniscus were the major restraints during the stance phase of gait, whereas the MCL and ACL were the key restraints during the swing phase. The contributions of the ovine structures for a simulated 6 DOF in vivo motion are similar to the roles previously reported for the human. The in vivo studies revealed that surgery to implant motion and force sensors decreased average and peak VGRFs less than 10% and 20%, respectively, across all combinations of speed and grade. VGRF measurements acquired before and after surgery were consistent among animals, with a coefficient of variation averaging no more than 18% for all activities. Increasing treadmill speed only increased hind limb peak VGRFs, whereas increasing treadmill grade significantly increased hind limb average and peak VGRFs. Finally, we investigated the effect of motion recording and recreation errors on kinetic measurements acquired using a robot. The starting position of the in vivo ovine motion was adjusted (perturbed) in each degree of freedom to levels comparable to the extents of our motion recording and recreation errors. Perturbing a simulated in vivo motion in each degree of freedom indicated that only translational perturbations significantly affected the intact knee and ACL kinetics. Also, the average ACL resultant forces across all subjects and perturbations were less than 10% of the average ACL failure load. This dissertation characterized the ovine stifle joint as a biomechanical surrogate for the human knee and validated a robotic methodology for measuring 3D joint and tissue kinetics using in vivo motions acquired during relevant activities of daily living (ADLs). Based on the 3D knee kinetics, the ovine stifle joint is a suitable biomechanical surrogate for the human knee. The novel methodology used to measure the 3D knee kinematics and kinetics for various ADLs has many applications to future orthopaedic research, notably in the areas of functional tissue engineering and sports medicine.