1Basic Medical Sciences, Mercer University School of Medicine, 2Department of Mechanical Engineering, University of Massachusetts Amherst, 3Department of Anatomy, Kansas City University of Medicine and Biosciences, 4Department of Biology, Mercer University, 5Department of Anthropology, University at Albany
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Sutures with varying linear elastic properties have been tested using Finite Element Analysis (FEA) and have demonstrated limited impact on global skull mechanics. However, sutures behave nonlinearly during compression and tension. Due to the interdigitated configuration of the suture-bone interface, sutures have a higher material stiffness in tension than in compression. We hypothesized that the assignment of nonlinear homogeneous material properties would render more realistically behaving FE sutures. Nonlinear isotropic elastic material properties (E Tensile = 74MPa, E Compressive =27 MPa. From Popowics and Herring, 2007) were assigned to the zygomaticotempral sutures of a juvenile Rhesus macaque FE model and tested using nonlinear static simulations. Global strain patterns for the nonlinear models were comparable to models using linear elastic suture properties (E=17.3GPa, E=50MPa, and E=1MPa). Strain patterns within the nonlinear sutures were most similar to the E=1MPa linear model, suggesting limited influences of nonlinear elastic properties. However, strain modes within the sutures differed among all models. For example, up to 32.6% of sutural elements underwent changes in their strain mode (from compressive-dominant to tensile-dominant, or vice versa) from the nonlinear model to the 1MPa linear model. As strain modes in sutures are closely related to sutural placement and complexity (Herring and Mucci, 1991), the change in sutural elastic properties during growth, functional adaptation, and fusion may have significant biomechanical consequences. These findings warrant further study of sutural morphology and its interaction with biomechanics at a microanatomical level.
This project was funded by grants from the NSF HOMINID program (BCS 0725078, 0725126, 0725136, 0725183).