Modeling of Cortical Bone Adaptation due to Mechanical Loading
Bone is a living tissue which constantly undergoes a complex process of adaptation in response to its biochemical and mechanical environment in order to optimize its resistance to failure. The bone adaptation due to the mechanical loading is dependent on a combination of different mechanical stimuli such as the magnitude and frequency of the applied load, number of cycles, number of bouts, time between bounds, and other factors. In this presentation we present a model of adaptation in cortical bone which employs the finite element stress analysis coupled with an evolution law. The finite element model is generated from micro-computed tomography images of the rat ulna and the stress analysis is carried out using boundary and loading conditions on the rat ulna obtained from the experiments of Robling et al. (JBMR, 2002, Vol. 17, p. 1545). First, we use an elastic material model and a simple growth law with strain energy density as the mechanical stimulus to simulate the effects of the loading magnitude and the number of bouts of loading on a real rat ulna finite element model. Then, we include the effect of load induced fluid flow in cortical bone by modeling bone as a poroelastic material. Our analysis focuses on the growth behavior in a rat ulna due to oscillatory loading. We use the dissipation energy based the mechanical stimulus as the triggering stimulus for adaptation using arguments based on the second law of thermodynamics. Very good agreement is found with the experiments of Robling et al. (2002). Finally we discuss bone’s hierarchical structure and extensions of the present study to multiscale modeling of the mechanotransduction in bone with a focus on cell/matrix mechanobiology.
Bio
Iwona Jasiuk received her Ph.D. in theoretical and applied mechanics at Northwestern University. Prior to joining the faculty of mechanical engineering at the University of Illinois at Urbana-Champaign (UIUC), she held academic positions at Michigan State University, Georgia Institute of Technology, and Concordia University. She also holds an affiliate faculty position in Bioengineering Department and part-time faculty positions at Institute for Genomic Biology and Beckman Institute at UIUC. Her expertise is in mechanics of materials, including biological and bioinspired materials. Her research addresses characterization of structure, composition and properties of materials at different structural scales and multiscale modeling. She is a co-editor of Journal of Mechanics of Materials and Structures and has served on editorial boards of the International Journal of Solids and Structures, International Journal for Multiscale Computational Materials, International Journal of Damage Mechanics, Computers in Biology and Medicine, Journal of Surfaces and Interfaces in Materials, and Frontiers in Biomechanics, among others. She is a Fellow of the American Society of Mechanical Engineers since 2003, a Fellow of the Society of Engineering Science (SES) since 2012, and in 2006 she served as president of the SES. Society of Engineering Science.