The relative influence of model parameters on finite element analysis simulations of intervertebral body fusion device static compression performance.

Non-clinical mechanical performance testing is a critical aspect of intervertebral body fusion device (IBFD) development and regulatory evaluation. Recently, stakeholders have begun leveraging computational modeling and simulations such as finite element analysis (FEA) in addition to traditional bench testing. FEA offers advantages such as reduced experiment time, lower costs associated with elimination of bench testing (e.g. specimen manufacture and test execution), and elucidating quantities of interest that traditional testing cannot provide (e.g. stress and strain distributions). However, best practices for FEA of IBFDs are not well defined, and modeler decision making can significantly influence simulation setup and results. Therefore, the goal of this study was to determine the relative influence of modeling parameters when using FEA to assess non-clinical mechanical performance of IBFDs. FEA was used to conduct a series of IBFD static uniaxial compression simulations. Several parameters relating to implant geometry, loading/boundary conditions, and material properties were carefully controlled to assess their relative influence on two output variables (IBFD stiffness and yield load). Results were most influenced by device geometry, while the effects of boundary conditions and material properties were more significant within IBFDs of identical or similar geometries. These results will aid stakeholders in the development of standardized best practices for using FEA to assess non-clinical mechanical performance of IBFDs.