[The relationship between electrical callus formation and the amount of electricity]

Electrical stimulation to enhance callus formation has been in use for some time now. This experiment was undertaken to find the relationship between electrical callus formation and the amount of electricity. In this experiment, the long bones of canines were stimulated by direct current and observed microscopically for callus formation. Moreover, distribution patterns of electric potential and current density were calculated theoretically by finite element method. The results are summarized as follows: Electrical callus formation was observed in the medullary canal with 8.7-20 microA direct current. Electrical callus is fibrous ossification and the peak of callus formation is from fourteen to twenty one days. There is no difference in volume and/or speed of callus formation between the simple and the constant direct current. Using platinum electrodes, the amount of callus formed around the cathode and anode is the same. To prevent electrolysis of the tissues, distance between electrodes must be kept at a minimum. On the other hand, the surface area of the electrodes must be widen to keep the electric potential at the minimum level. The area of callus formation is related to 5-10 microA/cm2 of electric current density.