Abstract:

Osteoporosis is a disease known to promote bone fragility but the effect on the mechanical
properties of bone material, which is independent of geometric effects, is particularly
unclear. To address this problem, micro-beams of osteoporotic bone were prepared using
focused ion beam microscopy and mechanically tested in compression using an atomic
force microscope while observing them using in situ electron microscopy.This experimental
approach was shown to be effective for measuring the subtle changes in the mechanical
properties of bone material required to evaluate the effects of osteoporosis. Osteoporotic
bone material was found to have lower elastic modulus and increased strain to failure
when compared to healthy bone material, while the strength of osteoporotic and healthy
bone was similar. Surprisingly, the increased strain to failure for osteoporotic bone material
provided enhanced toughness relative to the control samples, suggesting that lowering of
bone fragility due to osteoporosis is not defined by material performance. A mechanism is
suggested based on these results and previous literature that indicates degradation of the
organic material in osteoporosis bone is responsible for resultant mechanical properties.