We present a finite element study of a poroelastic rectangular beam subjected to
oscillatory bending loads. This geometric model is chosen for simplicity, as an
idealized representation of cortical bone. We then propose the use of the dissipation
energy of the poroelastic flow as a mechanical stimulus for bone adaptation, and
show that it can predict the effect of frequency of the applied load. Surface
adaptation in the model depends on the weighted average of the mechanical
stimulus in a “zone of influence” near each surface point, in order to incorporate
the non-locality in the mechanotransduction of osteocytes present in the
lacunae. We show that the dissipation energy stimulus and the resulting
increase in second moment of inertia of the cross section increase linearly with
frequency in the low frequency range (less than 10 Hz) and saturate at the
higher frequency range (greater than 10 Hz). Similar non-linear adaptation
frequency response also has been observed in numerous experiments. Our
framework is readily extended to the modeling of cortical bone using actual bone
geometries.
Keywords
poroelasticity, dissipation energy, interstitial fluid
flow, cortical bone adaptation, finite element modeling,
evolution law