ABSTRACT
The purpose of this study was to design, develop, and test a device that continuously maintains a constant potential at a cathode with respect to a reference electrode by automatically varying the potential between 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 failure. This constant cathodic potential device permits delivery of current at an optimal cathodic potential for faradic stimulation of osteogenesis which involves a net transfer of charge through biological tissue between, typically, an implanted cathode, the negative electrode where osteogenesis occurs, and either an implanted or a topical anode, the positive electrode required only to complete the electrical circuit. Unlike present devices that maintain a constant direct current between a cathode and an anode but permit potential between said electrodes to vary, this device presents the possible detrimental effects of an undesired electrochemical reaction due to an excessive cathodic potential.
Subject(s)
Electric Stimulation/instrumentation , Electric Stimulation/methods , Osteogenesis , Animals , Electrodes , Equipment Design , Potentiometry/instrumentation , Potentiometry/methods , Regeneration , Time FactorsABSTRACT
The purpose of this study was to determine whether or not surgical floor mats affect low back and leg muscle activity during prolonged standing. The EMG activity was measured continuously using surface electrodes on the paraspinal muscles of the low back and on the anterior tibialis muscles; the subjects were normal and stood on two different surfaces. Six male subjects were each instructed to stand for two hours on a specially designed surgical floor mat and then, on a separate day, to stand for two hours on a linoleum-covered concrete surface. Six other subjects carried out the same procedure, but stood on the linoleum first. There was no difference in EMG activity obtained from the anterior tibialis muscles and paraspinal muscles of the low back when the subjects stood on the surgical mat, as compared with the linoleum-covered concrete.
Subject(s)
Electromyography , Ergonomics , Floors and Floorcoverings/standards , Low Back Pain/diagnosis , Occupational Diseases/diagnosis , Adult , Body Weight , Evaluation Studies as Topic , Health Occupations , Humans , Low Back Pain/etiology , Low Back Pain/prevention & control , Male , Occupational Diseases/etiology , Occupational Diseases/prevention & control , Time FactorsABSTRACT
Studies of electrical stimulation of osteogenesis with stainless steel electrodes have previously established a dose-response relationship between current and bone growth. Examination of the effect of differing geometric current densities resulted in the conclusion that very little electrode surface area was involved in stimulation and led to the design of a multiport "distributive" cathode. A series of experiments were performed to extend these results to wire and multiport platinum electrodes. As before, a current-bone growth dose-response relationship was found. Peak bone growth was greater than for stainless steel. However, peak bone growth occurred at 2.0 microA (versus 20 microA for stainless steel). Correlation studies suggest that small changes in cathodic potential affect bone growth more than similar size changes in current. Finally, the generally benign local host response to platinum suggests that platinum may be a suitable material for chronic indwelling anodes for stimulation of osteogenesis.
Subject(s)
Electric Stimulation/instrumentation , Osteogenesis , Animals , Male , Platinum , Rabbits , Stainless SteelABSTRACT
A constant direct current cathode was employed in the medullary canal of the rabbit tibia to investigate electrical osteogenesis at low current levels. Currents of 0.015 or 0.075 microA were delivered to the bone and the biological response was compared with contralateral controls receiving 20 microA. This investigation was performed to determine if electrical osteogenesis occurs at current levels below the previously studied range of 1-100 microA with stainless steel electrodes. New bone formed by 0.015 microA cathodes was statistically comparable with that found around inactive cathodes from an earlier pertinent study. The osteogenic response to 0.075 microA cathodes was significantly elevated above that to inactive ones, thus substantiating electrical osteogenesis for currents below 1 microA. However, it is evident that this does not demonstrate a further stimulatory range but that currents near 0.075 microA probably approach the lower significant limit for electrically induced bone growth with stainless steel electrodes.
