Direct current influence on bone formation in titanium implants.

A dividable, titanium implant was inserted bilaterally in assembled form in the tibial metaphyses of adult rabbits. A titanium cathode was placed 5 mm proximal and a platinum-iridium anode 5 mm distally. The chamber on one side served as a non-stimulated control: on the other side the electrodes were connected to a constant current generator. Ten animals were treated with 5 microA, ten with 20 microA and ten with 50 microA. After three weeks the implants were removed, taken apart and the bone which had grown into two central canals of the chamber was collected for macroradiographic and computer-based numerical analysis. DC-stimulation with 50 microA did not result in any measurable increase of bone formation in the test implants compared to the controls. After stimulation with 5 or 20 microA, on the other hand, there was a statistically significant increase of osteogenesis, in spite of the fact that the electrodes were situated at some distance from the implant.