In Vitro Study of Electric Impedance of Bone

Abstract

In the last few years, electric stimulation has been widely recognized by many investigators as a valuable tool for stimulating bone growth. However, few of them have studied the electric conduction parameters of bone. In fact, little is known about the nature of the conduction mechanism or the current path between the electrodes. Furthermore, the great discrepancy in the results (1, 4) is due mainly to the different measurement procedures used, which induce various polarization phenomena relating to electrodes. To optimize the geometric factors in electric stimulation of bone growth, it might prove advantageous to use a model of equivalent bone impedance. In this study, we have measured in vitro, with alternating current, bone impedance under various conditions to determine the local impedance of the various parts of the diaphyseal bone (cortex and marrow space). A lumped-constant electric model is proposed for diaphyseal bone, taking into account longitudinal and transverse resistances of cortex and marrow. The normally distributed resistances per unit of length of bone occur in a single section of the model as lumped resistors.