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Educational Background:
Areas of Research Interest: My research activities include investigations in computational and experimental mechanics with emphasis on constitutive modeling, finite element methods, and mechanical testing and analysis within the general area of musculoskeletal biomechanics. These projects focus on 1) basic research in modeling bone damage behavior, and how bone quality relates to the general problem of skeletal fragility and the mechanics of fracture, 2) connecting engineering models with clinical applications, particularly the long-term prediction of fracture risk, and 3) investigating the role of genetic effects in describing variation in bone geometry and compositional and material properties. An orthotropic constitutive model has been developed to describe the combined continuum-level effects of viscoelastic, viscoplastic, and time-dependent damage behavior exhibited in trabecular and cortical bone under experimental loading. In ongoing investigations, this model is being refined to further characterize the plasticity and damage growth in bone at both the apparent level and the microstructural level. We are also developing methodology to predict long-term patient-specific fracture risk by incorporating routine clinical imaging measures of current heterogeneous bone condition for an individual patient within a continuum modeling approach. This work involves using probabilistic methodology to model the inherent randomness and uncertainty that exists in the descriptions of geometry, density, and bony architecture for skeletal structures. The third area of research involves characterization of the geometry, composition, and material properties of bone and the variation in these phenotypes; heritability analyses are conducted by colleagues at the Southwest Foundation for Biomedical Research in order to quantify the proportion of phenotypic variation that can be explained by genetic effects after the effects of age, sex, and age-sex interaction are removed. Selected Publications: Havill LM, Allen MR, Bredbenner TL, Nicolella DP, Burr DB, Turner CH, and Mahaney MC. Heritability of Lumbar Trabecular Bone Mechanical Properties in Baboons. Annual Meeting of the American Society of Bone and Mineral Research, Honolulu, HI, 2007 (accepted). Bredbenner TL, Havill LM, Mahaney MC, and Nicolella DP. Heritability of the Principal Components of a Statistical Shape Model Describing Baboon Midshaft Femur Geometry. Annual Meeting of the American Society of Bone and Mineral Research, Honolulu, HI, 2007 (accepted). Bredbenner TL and Nicolella DP. A Methodology for Bone Strength Prediction using Parametric Statistical Shape and Density Finite Element Modeling. Annual Meeting of the American Society of Bone and Mineral Research, Honolulu, HI, 2007 (accepted). Bredbenner TL and Nicolella DP. Simulation of Fall Loading using a Probabilistic Shape-Based Finite Element Model of Human Femurs. Summer Bioengineering Conference, American Society of Mechanical Engineers, Keystone, CO, June 2007. Bredbenner TL, Nicolella DP, and Davy DT. Modeling Variability in the Nonlinear Experimental Response of Trabecular Bone. Annual Conference of the Society for Experimental Mechanics, Springfield, MA, June 2007. Bredbenner TL and Davy DT. The effect of damage on the viscoelastic behavior of human vertebral trabecular bone. Journal of Biomechanical Engineering 128(4): 473-480, 2006. Havill, LM, Bredbenner, TL, Nicolella, DP, and Mahaney, MC. Normal variation in cross-sectional geometry of the femoral midshaft in baboons is heritable and is associated with levels of ANKH expression. Annual Meeting of the American Society for Bone and Mineral Research, Philadelphia, PA, 2006. Bredbenner TL, Snyder SA, Mazloomi FR, Le T, and Wilber RG. Subtrochanteric fixation stability depends on discrete fracture surface points. Clinical Orthopaedics and Related Research (432), 2005. Bredbenner TL, Nicolella, DP, and Davy DT. Damage accumulation in vertebral body models with simulated bone loss and the effects of BMD error in response predictions. Summer Bioengineering Conference of the American Society of Mechanical Engineers, Vail, CO, 2005. Contact Information: Southwest Research Institute 6220 Culebra Road San Antonio, TX 78238 Phone: 210-522-3565 Fax: 210-522-6965 todd.bredbenner@swri.org |
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