SPREADSHEET METHOD FOR CALCULATING THE INDUCED CURRENTS IN BONE-FRACTURE HEALING BY A LOW-FREQUENCY MAGNETIC-FIELD

A commercially available spreadsheet program is used on a microcompute r to calculate the induced current density and electric field patterns produced in a nonhomogeneous, anisotropic model of tissue by a locali zed, low-frequency magnetic-field source. Specific application is made to coils used to promote the healing of bone fractures in limbs. The variation of the conductivity of the fracture gap during healing cause s the induced current density pattern to change correspondingly, where as the induced electric field remains relatively unchanged. Use of mor e simplified, isotropic models for the bone and for the soft tissue le ads to results that differ significantly from those obtained from the full model. The magnetic field beyond the region of the coils contribu tes little to the induced currents in the fracture gap if the gap is l ocated near the center of the coils. (C) 1994 Wiley-Liss, Inc.