Electromechanical potentials in cortical bone--I. A continuum approach.
An electrokinetic model to characterize the electromechanical effect in cortical bone has been developed using the basic principles of the biphasic theory of porous materials and a simple model for permeability and charge distribution for cortical bone. The model is developed analytically in Part I of this paper and is shown to account qualitatively for the principal experimental results reported to date. Part II of this paper concerns experimental analysis of this model, reporting results of low frequency testing of the dynamic characteristics of stress-generated potentials. Quantitative analysis of these results indicates that the microporosity of bone, made up of the channels around the hydroxyapatite encrusting the collagen matrix, is the compartment responsible for the electromechanical effects in fluid-saturated cortical bone. This microporous compartment would seem to be the obvious source of the electrokinetic effect, because it has the greatest surface area in bone and constitutes the rate limiting fluid flow compartment in deformation-induced fluid flow at low frequency.