On incorporating osmotic prestretch/prestress in image-driven finite element simulations of cartilage

Xiaogang Wang; Thomas S E Eriksson; Tim Ricken; David M Pierce

doi:10.1016/j.jmbbm.2018.06.014

On incorporating osmotic prestretch/prestress in image-driven finite element simulations of cartilage

J Mech Behav Biomed Mater. 2018 Oct:86:409-422. doi: 10.1016/j.jmbbm.2018.06.014. Epub 2018 Jun 15.

Authors

Xiaogang Wang¹, Thomas S E Eriksson², Tim Ricken³, David M Pierce⁴

Affiliations

¹ Department of Mechanical Engineering, University of Connecticut, Storrs, CT, USA.
² Department of Defense and Security, System and Technology, Weapons and Protection, FOI - Swedish Defense Research Agency, Stockholm, Sweden.
³ Institute for Mechanics, Structural Analysis and Dynamics, Stuttgart University, Stuttgart, Germany.
⁴ Department of Mechanical Engineering, University of Connecticut, Storrs, CT, USA; Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA. Electronic address: dmpierce@engr.uconn.edu.

PMID: 30031245
DOI: 10.1016/j.jmbbm.2018.06.014

Abstract

Medical imaging performed in vivo captures geometries under Donnan osmotic loading, even when the articulating joint is otherwise mechanically unloaded. Hence patient-specific finite element (FE) models constructed from such medical images of cartilage represent osmotically induced prestretched/prestressed states. When applying classical modeling approaches to patient-specific simulations of cartilage a theoretical inconsistency arises: the in-vivo imaged geometry (used to construct the model) is not an unloaded, stress-free reference configuration. Furthermore when fitting nonlinear constitutive models that include osmotic swelling (to obtain material parameters), if one assumes that experimental data-generated from osmotically loaded cartilage-begin from a stress-free reference configuration the fitted stress-stretch relationship (parameters) obtained will actually describe a different behavior. In this study we: (1) establish a practical computational method to include osmotically induced prestretch/prestress in image-driven simulations of cartilage; and (2) investigate the influence of considering the prestretched/prestressed state both when fitting fiber-reinforced, biphasic constitutive models of cartilage that include osmotic swelling and when simulating cartilage responses. Our results highlight the importance of determining the prestretched/prestressed state within cartilage induced by osmotic loading in the imaged configuration prior to solving boundary value problems of interest. With our new constitutive model and modeling methods, we aim to improve the fidelity of FE-based, patient-specific biomechanical simulations of joints and cartilage. Improved simulations can provide medical researchers with new information often unavailable in a clinical setting, information that may contribute to better insight into the pathophysiology of cartilage diseases.

Keywords: Backward displacement method; Cartilage; Constitutive modeling; Finite element analysis; Medical imaging; Osmotic pressure.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Biomechanical Phenomena
Cartilage*
Compressive Strength
Finite Element Analysis*
Osmosis*
Stress, Mechanical*