This paper presents a method for determining the macroscopic continuum values of the electric field and current density in a three dimensional geometry with multiple tissues, so that a better approximation for the electromagnetic dose may be defined for cases of 60 kHz signals applied to surface electrodes. The three dimensional model enables parametric studies: changing conductivity values with time in the callus; changing electrodermal admittance values; various osteotomy sizes; limb length differences; and limb diameter variations.