A new method of comparative bone strength measurement

Most investigations of the material properties of bone have been concerned with the measurement of absolute values for various mechanical parameters. It can be necessary, however, to produce test samples with similar mechanical properties in order to assess the effect on these properties of particular treatments. Absolute values for these properties may not be as important as any changes observed. We describe here a new method whereby many bone test samples with very similar mechanical properties can be produced. If the femoral shaft at the diaphysis is cut in transverse section, it is possible to produce many similar shaped rings of bone. We compared the material properties of 48 ring samples with 65 beam specimens. Both were tested in three-point bending. Global estimates of coefficient of variation (CV) for each parameter were used to assess similarity within each group. All the rings had very similar ash weights (1.98%), thicknesses (1.97%), and diameters (< 0.01%). Values of load/deflection of the rings were more similar than the values of Young's modulus (E) for the beams (7.06 versus 9.9%), and the maximum loads sustainable by the rings were more similar than the bending strengths of the beams (5.7 versus 13.6%). The energy absorbed by the ring samples were more consistent than the beams (14.31 versus 34.41%). We suggest that there is improved similarity in mechanical characteristics within groups of samples produced in this manner than with more conventional sample configurations.