Electrical potentials in medullary bone.

In two-month-old rabbits, consistent reading with freshly prepared silver-silver chloride electrodes using a glass tube with an ionic transfer plug and a solution of KCl saturated with AgCl disclosed an intramedullary metaphyseal voltage of 1.5-9.0 mV. The proximal metaphysis was positive. Histologic studies of the reaction to implanted constant direct current of 7.5, 15.0 and 30.0 mA suggest the presence of an intramedullary current, with the polarity of the proximal metaphysis negative. There was an osteogenic response to the electrodes in all of the animals. The effect of adjacent muscle on intramedullary current requires further investigation. The effect of normally occurring intramedullary current on dummy electrodes in the process of fracture healing warrants more study.