In Silico Interaction of Adaptive Tissues and Devices a Dissertation Submitted to the Department of Mechanical Engineering and the Committee on Graduate Studies of Stanford University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy
چکیده
Finite element simulations were introduced in the aviation industry in the 1970s and soon found their way into other industries as well as biomedical research. Since then, constitutive laws have been developed with the goal of building realistic organ level models and ultimately creating a whole human model. The attempts to model the fibrous soft tissue in the human body has led to the development of anisotropic models as conceived by Fung or Holzapfel and active muscle models as developed by Hill. These models have led to a better understanding of the underlying biomechanics in both passive and active systems and their interaction with devices or changing boundary conditions during disease. However, the human body’s ability to adapt to boundary conditions, particularly in conjunction with devices or disease, has been ignored in most of these models. Here, I present constitutive laws for soft tissue adaptation, their implementation into general purpose finite element codes, and applications to clinically relevant problems. I applied a continuum mechanics framework to model the in-plane area growth of skin upon overstretch, the adaptation of skeletal muscle to changes in its mechanical environment, and the e↵ect of annuloplasty ring sizes during mitral valve repair surgery. Our results demonstrate how the finite element method can be applied to model the interaction of adapting soft tissue with medical devices and changing mechanical changes in ite environment. We anticipate our models to open new avenues in surgical planning and to enhance the treatment of patients in both plastic and cardiovascular surgery. Furthermore, I expect these models to be used by medical device manufacturers as part of their computer-aided engineering pipelines.