A CONSTANT CATHODIC POTENTIAL DEVICE FOR FARADIC STIMULATION OF OSTEOGENESIS

The purpose of this study was to design, develop, and test a device th at continuously maintains a constant potential at a cathode with respe ct to a reference electrode by automatically varying the potential bet ween the cathode and an anode. The ability of the device to maintain a constant cathodic potential with respect to a silver/silver chloride reference electrode is demonstrated in acute testing with a variety of electrodes as well as in chronic testing conducted until battery fail ure. This constant cathodic potential device permits delivery of curre nt at an optimal cathodic potential for faradic stimulation of osteoge nesis which involves a net transfer of charge through biological tissu e between, typically, an implanted cathode, the negative electrode whe re osteogenesis occurs, and either an implanted or a topical anode, th e positive electrode required only to complete the electrical circuit. Unlike present devices that maintain a constant direct current betwee n a cathode and an anode but permit potential between said electrodes to vary, this device prevents the possible detrimental effects of an u ndesired electrochemical reaction due to an excessive cathodic potenti al.