The effects of varying current levels of electrical stimulation.

An effort has been made to find an experimental delayed union of a long bone that could be used to evaluate the osteogenic effect of different current strengths. It is important that the optimum current strength be determined. Any such model should be able to produce a difference in new bone formation with an active and an inactive stimulator, particularly one using a 20 microA direct current. Attempts to produce a nonunion model in dogs were unsatisfactory, possibly because the defect was too small and surrounded by normal bone, and excessive movement occurred at the cathode plate. The optimum range of electrical stimulation using a titanium cathode has not been established by this work. The changes in serum alkaline phosphatase, serum calcium and serum phosphorus concentrations in response to trauma have been shown to be the same in the bone formation induced by electrical current.