Integration of functional daily living motor tasks into a novel cadaveric physiological knee simulator

Characterization of knee joint biomechanics, such as kinematics and kinetics, is essential for understanding the biomechanical impact of currently used or newly developed prostheses, surgical methods and rehabilitation strategies in the knee joint. This is because one of the main goals of knee joint arthroplasty is to restore native joint biomechanics. In day-to-day clinical practice, as well as in surgical training, subjective assessments of joint biomechanics such as passive motion and joint laxity are mainly used. In contrast, physiological simulators can objectively and accurately document the biomechanical behavior of cadaveric knees during weight-bearing functional motor tasks, such as squatting. In addition, these simulators are not limited in terms of invasiveness, usability, time and cost compared to the more classical in vivo evaluation. A novel physiological knee simulator has recently been designed by the Institute for Orthopedics Research and Training (IORT), which allows the mechanical control of multiple degrees of freedom at the ankle, such as anterior-posterior, medial-lateral and inferior-superior translations, as well as multiple muscle groups such as quadriceps, right and left hamstrings. More importantly, in addition to the squatting motion, the design specifically focuses on facilitating the simulation of more complex and clinically relevant functional motions such as stair climbing and descending, sitting-to-stand movements, gait and cycling. Nevertheless, to our knowledge, control strategies for accurate, physiological simulation of such complex locomotor activities of daily life have not yet been described or evaluated in the literature. Therefore, this thesis aims to: (1) biomechanically validate and validate the repeatability of this novel knee simulator in terms of the squatting motion by comparing it with a former validated Oxford-based knee rig at the IORT, (2) to simulate and assess the biomechanical parameters in terms of kinematics and kinetics for daily living activities - stair climbing, descending, sit-to-stand, walking and cycling. For this purpose, previously collected in vivo dataset will be used to determine the underlying forces with the help of inverse kinematics and dynamics and then integrate it into the in-house developed novel physiological knee simulator, (3) to compare the acquired simulated kinematics and kinetics for such motions with available in vivo and in silico data sets, (4) to validate the kinematic and kinetic repeatability of daily life activities using cadaver knee specimens.