Micromechanical modelling of normal, drug treated and osteoporotic bone using scanning acoustic microsopy and finite element analysis

Abstract

Ultrasonic methods were exclusively used to image cortical bone at high resolutions. A scanning acoustic microscope was used at a frequency of 150 MHz giving a resolution of 20μm. Images were taken of ovine bone samples from the "Bone for Life" PRTLI funded project. These were available in three types; ovariectomised (OVX), control (CON) and ovariectomised drug treated (OVX-ZOL). These samples exhibit changes in bone due to estrogen withdrawal. These samples were available at two time points; 12 months (OVX n=6, CON n=6), and 31 months (OVX-ZOL n=3, OVX, n=3, CON n=3). The images of cortical bone microstructure captured by SAM were converted into representations of Young's modulus values across the bone samples. Three areas were chosen randomly in each sample for analysis using Finite Element Analysis (FEA). A physiological strain of 1500 μ strain was applied. The resulting stresses and strain were analysed for each sample type.