Doctor of Philosophy (PhD), Wright State University, 2020, Engineering PhD

This research focuses on the hierarchical structure of bone and associated mechanical properties at different scales to assess damage accumulation leading to premature failure, with or without instrumentation. In this work, an attempt was made to develop a framework of macro, micro, and nano damage accumulation models and implementing them to derive mechanical behavior of the bone. At macrolevel, retrospective evaluation of 313 subjects was conducted, and the damage of bone tissue was investigated with respect to subject demography including age, gender, race, body mass index (BMI), height and weight, and their role in initiating fracture. Experimental data utilized 28 human femoral bones implanted with cephalomedullary nails were used to develop damage prediction models. Investigation of three real life medical device failures identified the mechanical and clinical bases of bone failure. At the micro level, microdamage accumulation of the bone was investigated in 307 subjects and new effective morphological parameters at microscale were proposed. At the nano level, molecular dynamics simulation was performed to investigate the effect of interaction, orientation, and hydration on the atomic models of the bone composed of collagen helix and hydroxyapatite crystal. The results showed that bone density and maximum von Mises stress decreased drastically in elderly patients, implying fixation devices and implants used by the young cannot be used. The results also showed that the two-dimensional representation of the morphological parameters of the bone at microscale does not provide a realistic description of bone structure. Therefore, in this work, three-dimensional representations at microscale indicated that bone interconnectivity is higher in female patients than in male patients. Gender has a significant effect on microdamage distribution in the bone. More precautions should be taken into consideration for older female patients. Race should also be considered during (open full item for complete abstract)

Committee: Tarun Goswami D.Sc. (Advisor); Caroline GL Cao Ph.D. (Committee Member); Arnab K. Shaw Ph.D. (Committee Member); Partha P. Banerjee Ph.D. (Committee Member); Richard T. Laughlin M.D. (Committee Member); Jennie J. Gallimore Ph.D. (Committee Member) Subjects: Biomechanics; Biomedical Engineering; Biomedical Research; Engineering; Industrial Engineering; Molecular Biology; Nanoscience; Nanotechnology