Effects of freeze-thaw and micro-computed tomography irradiation on structure-property relations of porcine trabecular bone.

We study the effects of freeze-thaw and irradiation on structure-property relations of trabecular bone. We measure the porosity, apparent density, mineral content, trabecular orientation, trabecular thickness, fractal dimension, surface area, and connectivity of trabecular bone using micro-computed tomography (micro-CT) and relate them to Young's modulus and ultimate strength measured by uniaxial compression testing. The analysis is done on six-month porcine trabecular bone from femoral heads. The effects of freeze-thaw are studied by using bones from three different groups: fresh bone and bones frozen for one and five years. We find that the porosity and apparent density have most dominant influence on the elastic modulus and strength of fresh bone. Also, five years of freezing lowers both Young's modulus and ultimate strength of trabecular bone. Additionally, the effects of radiation are investigated by comparing Young's modulus before and after micro-CT exposure. We find that the micro-CT irradiation has a negligible effect on the Young's modulus of trabecular bone. These findings provide insights on the effects of tissue preservation and imaging on properties of trabecular bone.