THE ACOUSTIC AND STRUCTURAL-PROPERTIES OF THE HUMAN FEMUR

This study evaluates the variations in the acoustic properties of the human femur at ten evenly spaced locations along its length, as well a s differences that exist within given transverse sections. Six pairs o f human femora, three male and three female, were sectioned, ground, a nd polished, and scanned with a microprocessor-driven scanning acousti c microscope. Images with a resolution of approximately 140 mu m were used to calculate the average acoustic impedances for each transverse cross section and each quadrant within a cross section. The mean acous tic impedance for all the cross sections was 7.69 +/- 0.18 Mrayls. Var iations were observed among the cross sections, and the central sectio ns (4-7) had values that were statistically greater than the other mor e distal and proximal sections. Within the cross sections, the posteri or quadrant had a lower average acoustic impedance compared to the oth er quadrants and this was statistically significant (Tukey's multiple comparison test). The cross sections were further analyzed to determin e several geometric parameters including the principal moments of iner tia, polar moment of inertia, and the biomechanical shape index. The p roduct of the acoustic impedance and the maximum moment of inertia pro vided a result that attempted to account for the acoustic property var iation and the change in shape at the different section locations.