OCLC: 847882575
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.
It was found that the year 1 sample types (OVX and CON) had the same means and standard deviations for Young’s modulus, equivalent stress and strain. They also shared the same distributions (p value= 0.28, Anderson Darling K test, Young’s Modulus).
For year 2 CON and OVX-ZOL samples had similar distributions for Young’s modulus, stress and strain (p value=0.49, Anderson Darling K test Young’s Modulus) . None of the other sample types shared a common distribution for Young’s modulus, equivalent stress or strain.
In comparing the distributions of OVX-ZOL with the CON sample types, it is evident for the year 2 samples that the anti-resorptive bisphosphonate drug (Zoledronic acid) has maintained bone properties, as measured by SAM, to a state similar to that of the disease free control samples.
The methods developed in this study can evaluate the tissue level micro-mechanical environment of cortical bone allowing an estimation to be made of the alteration ofthat environment by disease processes such as estrogen withdrawal induced osteoporosis. Evaluation can also be made ofthe effectiveness of drug treatments for osteoporosis.