Hahn, MikeMcGeehan, Michael2021-04-272021-04-272021-04-27https://hdl.handle.net/1794/26181Individuals with lower limb amputation face a variety of conditions associated with decreased quality of life, including elevated metabolic cost during ambulation, gait asymmetry, and a variety of psychological disorders. Sustained prosthesis use may also induce overloading of joints, leading to orthopedic injuries. These issues may be attenuated by improving user specificity in the design characteristics of foot prostheses. However, the effects of varied design parameters (e.g. stiffness) are not well characterized, and thus achieving meaningful improvements in gait mechanics has proven elusive. In order to achieve improvements, a robust understanding of the relationship between anthropometry, gait mechanics, and prosthesis design is necessary. Simulations based on computational gait models are powerful tools for evaluating potential biomechanical interventions, such as implementing a novel prosthesis. However, the utility of simulations to evaluate the effects of varied prosthesis design parameters on gait mechanics has not been fully realized due to lack of a readily-available limb loss-specific gait model and methods for efficiently simulating the mechanics of passive foot prostheses. The purpose of this dissertation was to develop computational models of a semi-active variable-stiffness foot prosthesis (VSF) and a limb loss-specific gait model to elucidate the relationships between anthropometry, gait mechanics, and variable prosthesis stiffness.This dissertation was divided into three distinct, yet related projects. Project 1 consisted of developing and validating a computational model of a VSF, a model of VSF-ground contact dynamics, and an optimization algorithm for programmatically deriving model parameters. In Project 2, a limb loss-specific gait model was developed and validated. Project 3 entailed developing a spatial contact model for the interface between the prosthetic socket and residual limb, and using that model for a simulation-based analysis of the effects of variable prosthesis stiffness on residual limb-socket dynamics. Projects 1 and 2 resulted in models and code for simulating gait with a VSF. Project 3 resulted in a reduced order spatial contact model of residual limb-socket interface dynamics. Simulated interfacial pressure and shear stress, as well as residual limb kinematics were similar to values previously reported in the literature. The effects of variable prosthesis stiffness on these outcomes were subject-dependent.en-USAll Rights Reserved.BiomechanicsComputational modelingComputational simulationMusculoskeletal modelingProsthesesRehabilitation engineeringElectronic Thesis or Dissertation