DUMONT, E.R.*; GROSSE, I.R.; COLETTA, C.E.; UMass, Amherst; UMass, Amherst; UMass, Amherst: Applying muscle forces to finite element models of bone: How much modeling precision is necessary?

Finite element analysis (FEA) is a powerful tool for understanding the mechanics of physical systems. Existing FEA tools were developed to enable engineers to predict the physical behavior of engineered products and manufacturing processes. The material properties, loading conditions, and especially geometries of these systems are fully specified by design engineers and easily defined in computer aided design (CAD) and/or FEA tools. In part due to the relatively simple shapes of the physical systems they study, engineers often use simple models to represent complex physical systems and place a high degree of confidence in analyses of those simplified models. FE modeling and analysis of biological structures is a much more complicated task. Organic structures inevitably contain complicated, irregular shapes and are often subjected to complex loading regimes. The extent to which models of biological structures can be simplified often is not clear and researchers invest a great deal of energy in creating �true-to-life� models. To begin to understand how FE models of biomechanical systems can be simplified without losing valuable information, we studied the effect of simple and complex models of muscle loads on the transmission of biting forces through the facial skeleton of a mammal. Using the same FE model, we conducted a series of analyses in which the major jaw adductors were modeled with increasing precision as point loads, evenly distributed tangential loads, tangential loads that changed in magnitude along a gradient, and tangential + normal loads that changed in magnitude along a gradient. Results indicate that all methods of modeling muscle loads return similar results and suggest that simple models of muscle loads can, in many cases, return reliable results.