Biomechanical Models For Soft Tissue Simulation

An overview of biomechanical modeling of human soft tissue using nonlinear theoretical mechanics and incremental finite element methods, useful for computer simulation of the human musculoskeletal system.

This volume focuses on the biomechanical modeling of biological tissues in the context of Computer Assisted Surgery (CAS). More specifically, deformable soft tissues are addressed since they are the subject of the most recent developments in this field. The pioneering works on this CAS topic date from the 1980's, with applications in orthopaedics and biomechanical models of bones. More recently, however, biomechanical models of soft tissues have been proposed since most of the human body is made of soft organs that can be deformed by the surgical gesture. Such models are much more complicated to handle since the tissues can be subject to large deformations (non-linear geometrical framework) as well as complex stress/strain relationships (non-linear mechanical framework). Part 1 of the volume presents biomechanical models that have been developed in a CAS context and used during surgery. This is particularly new since most of the soft tissues models already proposed concern Computer Assisted Planning, with a pre-operative use of the models. Then, the volume addresses the two key issues raised for an intra-operative use of soft tissues models, namely (Part 2) “how to estimate the in vivo mechanical behavior of the tissues?” (i.e. what are the values of the mechanical parameters that can deliver realistic patient-specific behavior?) and (Part 3) “how to build a modeling platform that provides generic real-time (or at least interactive-time) numerical simulations?”

The book presents a state-of-the-art overview of biomechanical and mechanobiological modeling and simulation of soft biological tissues. Seven well-known scientists working in that particular field discuss topics such as biomolecules, networks and cells as well as failure, multi-scale, agent-based, bio-chemo-mechanical and finite element models appropriate for computational analysis. Applications include arteries, the heart, vascular stents and valve implants as well as adipose, brain, collagenous and engineered tissues. The mechanics of the whole cell and sub-cellular components as well as the extracellular matrix structure and mechanotransduction are described. In particular, the formation and remodeling of stress fibers, cytoskeletal contractility, cell adhesion and the mechanical regulation of fibroblast migration in healing myocardial infarcts are discussed. The essential ingredients of continuum mechanics are provided. Constitutive models of fiber-reinforced materials with an emphasis on arterial walls and the myocardium are discussed and the important influence of residual stresses on material response emphasized. The mechanics and function of the heart, the brain and adipose tissues are discussed as well. Particular attention is focused on microstructural and multi-scale modeling, finite element implementation and simulation of cells and tissues.

This book constitutes the refereed proceedings of the International Symposium on Surgery Simulation and Soft Tissue Modeling, IS4TM 2003, held in Juan-Les-Pins, France in June 2003. The 33 revised full papers presented together with 3 invited papers were carefully reviewed and selected from 45 submissions. The papers are organized in topical sections on soft tissue models, haptic rendering, cardiac modeling, and patient specific simulators.

The articles in this book review hybrid experimental-computational methods applied to soft tissues which have been developed by worldwide specialists in the field. People developing computational models of soft tissues and organs will find solutions for calibrating the material parameters of their models; people performing tests on soft tissues will learn what to extract from the data and how to use these data for their models and people worried about the complexity of the biomechanical behavior of soft tissues will find relevant approaches to address this complexity.

Biomechanics of Living Organs: Hyperelastic Constitutive Laws for Finite Element Modeling is the first book to cover finite element biomechanical modeling of each organ in the human body. This collection of chapters from the leaders in the field focuses on the constitutive laws for each organ. Each author introduces the state-of-the-art concerning constitutive laws and then illustrates the implementation of such laws with Finite Element Modeling of these organs. The focus of each chapter is on instruction, careful derivation and presentation of formulae, and methods. When modeling tissues, this book will help users determine modeling parameters and the variability for particular populations. Chapters highlight important experimental techniques needed to inform, motivate, and validate the choice of strain energy function or the constitutive model. Remodeling, growth, and damage are all covered, as is the relationship of constitutive relationships of organs to tissue and molecular scale properties (as net organ behavior depends fundamentally on its sub components). This book is intended for professionals, academics, and students in tissue and continuum biomechanics. Covers hyper elastic frameworks for large tissue deformations Considers which strain energy functions are the most appropriate to model the passive and active states of living tissue Evaluates the physical meaning of proposed energy functions

Availability of advanced computational technology has fundamentally altered the investigative paradigm in the field of biomechanics. Armed with sophisticated computational tools, researchers are seeking answers to fundamental questions by exploring complex biomechanical phenomena at the molecular, cellular, tissue and organ levels. The computational armamentarium includes such diverse tools as the ab initio quantum mechanical and molecular dynamics methods at the atomistic scales and the finite element, boundary element, meshfree as well as immersed boundary and lattice-Boltzmann methods at the continuum scales. Multiscale methods that link various scales are also being developed. While most applications require forward analysis, e.g., finding deformations and stresses as a result of loading, others involve determination of constitutive parameters based on tissue imaging and inverse analysis. This book provides a glimpse of the diverse and important roles that modern computational technology is playing in various areas of biomechanics including biofluids and mass transfer, cardiovascular mechanics, musculoskeletal mechanics, soft tissue mechanics, and biomolecular mechanics.