A method for optimizing the treatment of infected metal implants by measuring charge transfer.

Abstract

A method and associated system for treating a metal surface to eradicate bacteria on the metal surface using at least three electrodes, wherein the metal surface is one of the electrodes, a stimulation voltage is applied to the metal surface, and an accumulated charge is measured. The accumulated charge is compared to a threshold level, and the stimulation voltage is maintained until the accumulated charge exceeds the threshold level. In at least one version, the metal surface is a metal surface of a surgical implant.

Description

Technical Field

[0001] (Cross - reference to Related Applications) This application claims the benefit of priority under 35 U.S.C. §§ 119 and 120 to U.S. Patent Application No. 63 / 047,308, filed Jul. 2, 2020. This prior application is hereby incorporated by reference in its entirety.

[0002] (Field of the Invention) This application generally relates to the field of treatment systems used to destroy or eradicate bacteria from metal surfaces. More specifically, this application is directed to systems and related methods or techniques for reliably controlling the treatment of implanted devices in infected metals based on measured charge transfer.

Background Art

[0003] Implants are used for patients with many different injuries or medical problems. For example, various surgically implanted orthopedic devices, such as knee, hip, and shoulder replacements, are routine. Similarly, implants can be used for any individual who needs to replace teeth in a dental procedure. These implants are typically made from metals such as titanium, cobalt - chromium, or stainless steel. A potential problem commonly associated with metal implants is that these devices tend to allow the growth of bacteria on their surfaces, increasing the risk of patient infection. When bacteria colonize a foreign surface such as metal, they form a biofilm. A biofilm is a protective extracellular matrix material that encapsulates bacterial colonies on the surface and protects the colonies. Biofilms can be 500 - 5000 times more resistant to antibiotics than typical planktonic bacteria because antibiotics cannot penetrate the biofilm.

[0004] Implant-associated infections are a devastating consequence of medical interventions, increasing patient morbidity and raising costs for healthcare systems. Unfortunately, current standard procedures often require removal of the infected implant, long-term antibiotic treatment, and eventual secondary replacement. More recent developments in this field provide treatment systems such as those described in U.S. Patent No. 9,616,142. The treatment system described can be performed on a patient without requiring removal of the implanted device. More specifically, according to this technique, an electrochemical cell is fabricated using two or more, preferably three, electrodes, each coupled to a device such as a potentiostat capable of delivering a stimulating voltage. A counter electrode and a stable reference electrode are each attached to the patient along with the working electrode, the latter being a metal implant, forming an electrochemical-based circuit. The applied stimulating voltage is sufficient to disrupt and eradicate the biofilm layer.

[0005] Unfortunately, the duration of treatment with electrical stimulation as described above before the infection is actually eliminated is unknown. Due to differences in patient physiology, fluid supply, fat content, and other patient-specific variables, each patient receives different levels of applied current while maintaining a constant voltage. Current methods do not allow for a scientifically and mathematically supported method to precisely determine how long treatment is needed to eradicate biomaterial-associated infections. Currently, treatment time is selected based on the assumption that it is long enough to kill the infection. However, this treatment period may not be long enough to be effective, or it may be longer than necessary, considering the number of patient-specific variables as described above.

[0006] The effects of electrical stimulation have been widely studied and are known to be bactericidal. The literature has shown that the total amount of treatment required to prevent or eradicate infection on metal surfaces is the driving force behind these effects. Treatment is not uniform, even when voltage or current is kept constant, because patients are of different sizes, have different physiological characteristics, and inherently different resistivity. Furthermore, the delivery of DC voltage does not scale proportionally with implant size, resulting in varying currents, and therefore, it is difficult to determine the total treatment based solely on size.

[0007] Therefore, there is a widespread need in this field to provide technologies that allow for more efficient and reliable treatment to eradicate bacteria from implanted devices. [Overview of the Initiative]

[0008] According to one embodiment, a method is provided for treating a metal surface to eradicate bacteria on the metal surface, the method comprising: applying a stimulating voltage sufficient to destroy the bacteria to the metal surface; measuring the accumulated charge over time; comparing the accumulated charge to a threshold level; and continuing to apply the stimulating voltage until the accumulated charge exceeds the threshold level.

[0009] In another embodiment, a system is provided for treating an infected metal implant, the system comprising: a device capable of applying a stimulating voltage; a working electrode coupled to the device capable of applying a stimulating voltage, which is a metal implant; a counter electrode coupled to the device capable of applying a stimulating voltage, which forms an electrochemical circuit with the working electrode; a reference electrode coupled to the device capable of applying a stimulating voltage, which forms an electrochemical circuit with the working electrode; and a processor programmed to measure the accumulated charge in order to control the duration of treatment of the metal implant.

[0010] The proposed invention is an improved method for treating patients suffering from metal implant-associated infections through charge-based electrical stimulation. This can be achieved using two, three, or four electrode systems. A preferred embodiment is a three-electrode stimulation treatment system due to its ability to provide a constant voltage through the use of a stable reference electrode. More specifically, the invention solves the problem of patient-specific factors affecting the time during treatment by measuring charge transfer as a method for preventing or eradicating infection on a metal surface. The invention requires measuring the total charge transferred to the implant, or integrating the current drawn from the stimulation source and supplied over time. The invention then utilizes the calculation of charge transfer to determine the amount of treatment delivered to the patient, and uses this calculation as a means to determine whether the implant infection has been adequately eliminated or prevented.

[0011] This invention relates to the use of voltage-controlled electrical treatment on metal surfaces as a method for preventing and eradicating microbial colony formation on surfaces. The invention is carried out when a DC current is applied to a metal implant. As described above, the treatment system requires at least two electrodes, but three or four electrodes can also be used. Specifically, according to a preferred embodiment, three electrodes are used, including a working electrode, a counter electrode, and a reference electrode. The counter electrode supplies current to the working electrode to maintain a stable DC potential relative to a stable reference electrode. A treatment system with two electrodes does not have a stable reference electrode, and therefore the voltage is unstable.

[0012] The present invention obtains information about the current delivered from the counter electrode to the working electrode and calculates the charge by integrating this value over time. This allows the measured accumulated charge delivered to the system during electrical stimulation to determine the level of treatment applied and the final duration of the treatment. The specific values ​​for these variables, which need to be bactericidal, depend on the specific conditions of the treatment, the surface area of ​​the infected implant, and the pathogen of interest. In addition, patient size, fluid supply, and other physiological parameters determine how much resistance exists from the skin-based counter electrode to the working electrode implant. As mentioned earlier, these parameters determine how much current flows through the implant and ultimately how much charge is delivered within a given time. This can vary considerably between patients, and two different patients may receive different treatments over a period of time with the same input parameters of the applied voltage. The present invention is preferable and advantageous because it normalizes the treatment across each of these variables, allowing a known charge-based treatment to be applied regardless of the stimulation input parameters, and its duration is no longer a determinant for completing the successful treatment.

[0013] Using the present invention, the precise amount of treatment can be determined through calculations of the total charge passed through the system and, as a result, how much infection is eliminated. This methodology normalizes eradication and preventive treatment times by taking into account differences in bodily resistance, current, duration, and voltage parameters. This method ensures that each patient receives the same treatment. According to at least one version, the treatment system can be configured to automatically terminate the treatment when the accumulated charge transfer reaches a predetermined threshold. In another version, the treatment system can be configured to interrupt the treatment even if the accumulated charge has not reached a predetermined threshold, but the treatment has exceeded a time threshold.

[0014] Charge-based treatment uniquely accounts for and considers all parameters between the patient's anatomical structure and the electrochemical treatment, thereby normalizing treatment for the prevention or eradication of infection on metal surfaces and ensuring that all patients are treated the same. This invention is unique in that it enables the accurate calculation of the total amount of charge transferred in real time, allowing normalized electrical stimulation treatment between patients to be achieved.

[0015] These and other features and advantages will be readily apparent from the following detailed description, which should be read in conjunction with the attached drawings. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 is a schematic diagram of an exemplary implant treatment system using the method described herein. [Figure 2A] Figure 2A is a graph comparing time-based and charge-based treatments between patients. [Figure 2B] Figure 2B is a graph comparing time-based and charge-based treatments between patients. [Figure 3] Figure 3 is a graph showing the accumulated charge transfer (in coulombs) for Ag / AgCl compared to the treatment period at -2.0V. [Figure 4] Figure 4 is a graph showing the relationship between charge transfer and viable colony-forming units (CFUs) for six clinically relevant bacterial strains, with the results indicating persistent biofilm-associated bacteria. [Figure 5] Figure 5 is a graph showing the relationship between charge transfer and viable colony-forming units (CFUs) for the six clinically relevant bacterial strains in Figure 4, and the results shown represent the remaining planktonic bacteria. [Modes for carrying out the invention]

[0017] The following describes a treatment method for eradicating bacteria from metal implants, such as orthopedic or dental instruments, using a stimulating voltage based on accumulated charge transfer. It will be understood that various modifications are possible within the scope of the intended invention.

[0018] As described above, electrical stimulation for infection control of metal implants can typically be implemented in two-, three-, and four-electrode systems, such as by applying a cathode stimulation voltage to the implant, which is the working electrode of the treatment system, via a potentiostat or similar device. The principle of this treatment system (CVCES) is described in U.S. Patent No. 9,612,142, which is incorporated herein by reference in its entirety. In a two-electrode treatment system, current is passed from the counter electrode to the working electrode, and the voltage on the working electrode can change. In this case, the current-carrying electrode is also used for sense measurement. The two-electrode system measures the total cell voltage drop across the electrochemical cell from the working electrode through the electrolyte to the counter electrode. The four-electrode treatment system measures the impedance across the solution phase interface, enabling accurate measurement of solution resistance or resistance across the surface of some material. However, the latter treatment system does not provide information about the electrochemical reactions occurring at the working electrode or counter electrode. The present invention is applicable to both two-electrode and four-electrode systems, but a three-electrode treatment system is preferred.

[0019] Therefore, a three - electrode treatment system 100 for use in accordance with the present invention is schematically shown in FIG. 1 and is shown more specifically as being used in connection with a surgically implanted knee joint replacement (implant 200) having metallic tibial and femoral components. A potentiostat 220 is electrically coupled to the implant 200 by at least one conducting wire 242 that includes a needle disposed in direct contact with the implant 200. The counter electrode 240 and the reference electrode 230 are also coupled to the potentiostat 220 via conducting wires 246 and 244, respectively. According to this exemplary embodiment, a processor 250 is coupled to the potentiostat 220 and is further programmed with treatment logic or software / firmware such that the current between the working electrode 200 and the counter electrode 240 is measured via separate leads 247, 248 connected to the working electrode lead 242 and the counter electrode lead 246, respectively, as described herein.

[0020] The three - electrode configuration separates the stable reference electrode 230 from the counter electrode 240 and positions the reference electrode 230 in proximity to the working electrode (e.g., implant 200). This configuration is clearly advantageous when compared to a two - electrode system because it only measures the potential at the working electrode, i.e., half of an electrochemical cell, and provides a clear indication of what is electrochemically occurring on the surface of that implant. Further, compared to a four - electrode system, the three - electrode configuration is preferred because this configuration enables a direct analysis of the electrochemical reaction on the working electrode. The potential change of the working electrode is measured independently of changes that may occur on the counter electrode. This isolation makes the three - electrode configuration a preferred treatment method in electrochemical experiments and is the basis for the preferred embodiments of the present invention.

[0021] All corrosion reactions have a cathodic half-cell reaction, an anodic half-cell reaction, an electrolyte solution, and a means of electron transport between the cathodic half-cell reaction and the anodic half-cell reaction. The application of electrical stimulation for infection control against metal implants is often maintained constant in the cathodic region using a three-electrode stimulation configuration. Metal implants are often passivated metals such as titanium alloys, stainless steels, and cobalt-chromium, among others. In the human body, soft tissues represent the means of electron transport. The cathodic half-cell reaction is represented by the reduction reaction of oxygen and water, and the anodic half-cell reaction consists of metal oxidation. The reaction rate is measured by the electron flow (current). The current delivered to the implant is affected by, among other things, the electrical input parameters and external factors such as patient resistance, the distance between the counter electrode and the working electrode, the distance between the counter electrode and the reference electrode, the resistance between the electrodes, and the size of the implant.

[0022] The amount of current received by the implant has a direct impact on the ability of the technique to eradicate and prevent infection, and more current is typically associated with a higher kill rate and effectiveness. Since each patient is different, a method is needed to normalize electrical stimulation for infection control for each patient to ensure that the expected bactericidal effect is achieved. The reduction reaction is dominant when there is a net cathodic current, and the oxidation reaction is dominant in the presence of a net anodic current. The reduction reaction of oxygen and water is represented by the following Equations 1 and 2. [Equation 1] Equation 1: O2 + H2O + 4e - → 4OH - [Equation 2] Equation 2: 2H2O + 2e - → H2 + 2OH -

[0023] At pH 7, similar to the pH of the human body, the standard reduction potential for oxygen reduction is +0.8V and the standard reduction potential for water reduction is -0.4V. At the applied cathode potential, the oxygen reduction reaction is diffusion-limited, and water reduction becomes the dominant cathode half-cell reaction. The potential applied for the prevention and eradication of infection from metal implants falls within the range of these oxygen and water reduction regimes. As seen in Equations 1 and 2, through the generation of OH (hydroxide ions) in both cases, the pH increases in the microenvironment directly surrounding the metal implant, killing the infection. The generation of OH depends on the reaction rate, as it is determined by the current (or electrons) flowing through the electrode-electrolyte interface. In the case of electrical stimulation for infection control in the human body, the resistance of the electrode-electrolyte interface varies greatly among patients. Therefore, even with the same applied voltage, the supplied current can vary. Since the rate of bactericidal activity depends on the generation of OH- and therefore on the current, the higher the current, the faster this can occur. Thus, the present invention relates to the reaction products of charge transfer, enabling different implants to undergo the same treatment from a constant voltage, but receiving different currents due to differences in resistance. The total amount of charge transferred to the system generates the same number of reaction products.

[0024] As the current increases, the production of OH- ions also increases. Therefore, this increased production makes the pH in the microenvironment surrounding the implant more alkaline, ultimately reaching a bactericidal level. At higher levels of charge transfer, the reaction completes more times, resulting in this increased pH more rapidly than at lower levels of charge transfer. This results in a more rapid bactericidal effect.

[0025] If patients are treated based solely on time, certain patients may receive excessive treatment, while others may not receive sufficient treatment to eradicate bacteria. The differences between time-based and charge-based treatment are illustrated in Figures 2A and 2B. Figure 2A shows a hypothetical example of what typically happens in the case of time-based stimulation voltage treatment for two different patients, namely patient A and patient B, with charge in coulombs plotted against treatment time (measured in hours). In this case, it is assumed that patient A (plot 620) and patient B (plot 640) have the same treatment voltage and time. As can be seen from the figure, therefore, in this exemplary example, patient A receives 4 coulombs and patient B receives only 2 coulombs, so it is possible that certain individuals may receive more or less treatment than necessary.

[0026] Figure 2B provides a visual representation of a charge-based procedure to illustrate the methodology of the present invention. In this representation, the procedure counts the accumulation of charge in the system, taking into account different rates of current delivery to different patients through resistance. Then, after a specified amount of charge is reached, the procedure is considered complete and no further treatment is delivered. In this hypothetical example, patient A completed the procedure in just 2 hours for plot 660, while patient B required 4 hours for plot 680. Thus, the aforementioned Figures 2A and 2B provide an extreme example of why the present invention is needed in the case of electrical stimulation for infection control of metal implants.

[0027] The present invention relates to a method for ensuring charge-based treatment for the delivery of electrical stimulation for the treatment and prevention of metal-associated biofilm infections. As described above, the methods described herein may include any or all of the following: 1. Sample the current every second, sum the sampled currents, and obtain real-time charge transfer data. 2. To determine the total charge at a given time, the current is integrated intermittently over time. 3. Stop the procedure when the threshold or target charge transfer procedure is achieved. 4. It has the ability to display the percentage of treatment completion based on accumulated charge transfer and to estimate the time until completion. 5. Provide an override function that allows the procedure to be stopped after a set amount of time, even if total charge transfer has not been achieved. Each of these features will be described in detail below to further illustrate the technology.

[0028] For the purposes of the following explanation, a treatment system such as the treatment system 100 in Figure 1 may include a specially programmed processor 250 coupled to a potentiostat 220, or the potentiostat 220 may be appropriately programmed without requiring a separate device 250. The amount of charge flowing into the system is specified by the current flow and the length of the current flow measured by the processor 250, which receives current from the working electrode 200 and counter electrode 240 via connecting leads 247, 248. Equation 3 shows the formula for calculating charge transfer. [Math 3] Equation 3: Q = I * t Here, Q is the charge measured in coulombs (C), I is the current measured in amperes (A), and t is the time measured in seconds (s). Given this information, the processor or potentiostat is programmed to measure and record the current output in amperes every second or at other predetermined sampling intervals, and to track the continuous sum of the current values. Based on Equation 1, this sum provides an indicator of the total charge transfer in coulomb units delivered to the treatment system after any given period of time during which the stimulation voltage was delivered.

[0029] An alternative to this method utilizes Equation 4, in which the current is intermittently integrated over time to determine the total charge. Equation 4 is as follows: [Math 4] Equation 4: Q=∫Idt

[0030] This is an alternative embodiment that allows the calculation of charge transfer through integration of a constant output current versus time plot. In this case, there is no need for a 1-second sampling period; instead, the sampling period can be much faster or slower. This yields the same result as the first idea expressed by Equation 1, but this method is more cumbersome and therefore an alternative embodiment.

[0031] A key distinction of this invention over current practices is its ability to terminate a procedure based on charge, as opposed to time or duration. According to the methodology of this invention, the delivery of current to the implant 200 is interrupted when the charge transfer reaches a specific predetermined set limit (accumulated charge transfer threshold) stored, preferably by a potentiostat or processor 250. For the purposes of this method, the total current is compared to the accumulated charge transfer threshold by the processor 250 in Figure 1, following each sampling. This is a crucial factor in current designs, as opposed to known time-based treatment systems and methodologies. Having a cutoff point or threshold when an appropriate amount of charge is achieved ensures that the patient is neither over-treated nor under-treated by electrical stimulation for implant infection control. According to one version, an estimated percentage of completion may be calculated by software and output for the patient or caregiver to view based on how much total charge was transferred at that moment. The system further comprises, in a preferred embodiment, a processor 250 or potentiostat 220, which is programmed to display a percentage of procedure completion (based on the amount of charge transfer measured / totaled) and estimate the time remaining until completion, enabling the patient to recognize how much time remains in their procedure.

[0032] In another embodiment, the potentiostat 220 or a separate processor 250 may further be programmed with a timer that automatically stops the stimulating treatment after a set amount of time, even if the total Coulomb movement threshold has not been achieved. It should be understood that during active treatment delivery, the patient remains mostly motionless. This lack of mobility is essential to ensure that the treatment applied is constant, that the electrical stimulator is not removed, and that a consistent charge is delivered to the patient. However, in reality, there is a limit to how long any patient can remain motionless. The charge-based treatment delivery described herein is not defined by a set time at which the treatment is applied to the implant. Therefore, if the treatment is prolonged due to factors related to the patient or due to a malfunction of the treatment system, the patient will remain motionless for too long. Accordingly, according to the preferred version, the treatment system described herein includes an override feature in which the processor is programmed to turn off the treatment when a total charge (threshold) is achieved or when a predetermined amount of time has been reached. The aforementioned termination feature maintains patient safety and eliminates the possibility of the patient having an excessively long treatment time.

[0033] The invention described herein represents a significant improvement over current treatment delivery parameters based on any given time period only. The invention utilizes real-time calculation of charge using current and time outputs to apply a predetermined charge level for a treatment. This methodology normalizes the results across applied voltages. In addition, the treatment is normalized for any difference in current between the counter electrode and the working electrode, which may result from variations in patient weight, skin / fat composition, conductivity due to fluid supply, implant material, and electrode placement. Finally, and most importantly, the methodology described herein ensures that all patients are given the same treatment through patient-specific treatment parameters.

[0034] Furthermore, the amount of charge transfer required to treat or prevent infection depends on the size of the implant. Larger implants have a greater total current through the electrode / electrolyte interface. Therefore, the total charge transfer increases as a function of implant size, and larger implants require more charge to reach a bactericidal level. This raises the important concept of charge density. 1cm 2 The charge passing through the implant material remains relatively constant across all implant sizes, but the total charge passing through the interface is a function of the implant size.

[0035] The aforementioned concepts and methodologies have been shown to be effective in the tests. Figure 3 shows data collected during the test empirically demonstrating Equation 4, where a longer treatment time results in a greater amount of charge transfer when treated with the same treatment voltage, which is shown for accumulated charge transfer (coulombs) over a period of 8 hours, taken periodically over time.

[0036] Figures 4 and 5 show a clear inverse relationship between viable colony-forming units (CFUs) and the accumulated charge transferred to the system during treatment for eradicating pre-formed biofilm structures, when comparing all durations from Figure 2 based on accumulated charge transfer. More specifically, Figure 4 shows the results obtained with increased charge transfer after different levels of treatment, including biofilm-associated bacteria from six different clinically relevant strains. Figure 5 shows data collected in tests showing the same relationships for viable planktonicity, buoyancy, CFUs, and accumulated charge for the same six clinically relevant strains as in Figure 4. In all cases, the greater the charge transferred to the system, the greater the decrease in viability.

[0037] One challenge that arose during the development of this invention involved understanding the value of charge transfer and how this parameter relates to killing bacteria. This challenge was addressed through key experiments using various pathogens and material types, as shown in Figures 3-5. These experiments made it possible to determine the minimum amount of charge required to kill various Gram-positive and Gram-negative pathogens. A further challenge was to provide a method for uniformly comparing data when there are differences in voltage, current, or duration. According to this invention, charge transfer can be used to calculate the amount of time required to perform a patient treatment at a specific voltage or current level for its bactericidal effect. This technique normalizes data from various different treatment parameters that could not otherwise be compared. As a result, the overall methodology of this invention improves patient treatment outcomes, as well as consistency of treatment delivery between patients.

[0038] It will be readily apparent that other modifications and / or variations are possible within the intended scope of the present invention and in accordance with the following claims. The following are also included in the nature of this disclosure: [Aspect 1] A method for treating the metal surface of an implantable device to eradicate infectious bacteria, a) A step of enabling a stimulating device for a treatment system capable of applying a DC voltage sufficient to destroy bacteria from the metal surface of the implantable device, wherein the DC voltage is applied between a pair of electrodes, one of which is the implantable device; b) A step of using the processor of the treatment system to measure the accumulation charge transfer to the metal surface of the implantable device over time, wherein the accumulation charge transfer is measured in coulombs, c) A step of comparing the accumulated charge transfer with a predetermined threshold level stored by the processor, d) A step of continuing to apply the DC voltage until the accumulated charge transfer exceeds the predetermined threshold, A method for treating the metal surface of an implantable device to eradicate infectious bacteria, including [specific bacteria]. [Aspect 2] The method according to embodiment 1, wherein the accumulated charge transfer is measured by sampling the current between the pair of electrodes over a periodic time interval and then summing the sampled currents. [Aspect 3] The method according to embodiment 1, wherein the accumulated charge transfer is measured by integrating the current between the pair of electrodes over a specific time interval. [Aspect 4] The method according to embodiment 1, further comprising continuing to apply the DC voltage until the accumulated charge transfer exceeds a predetermined threshold level or after a predetermined maximum period measured from the start of the procedure, whichever occurs first. [Aspect 5] The method according to embodiment 1, further comprising displaying the percentage amount of the completed treatment based on the measured accumulated charge transfer. [Aspect 6] The method according to embodiment 1, wherein the metal surface is made from at least one of stainless steel, cobalt-chromium, and titanium. [Aspect 7] The method according to embodiment 1, wherein the metal surface is the metal surface of a surgically implantable device. [Aspect 8] The method according to embodiment 1, further comprising coupling the metal surface to a potentiostat to which the stimulation voltage can be applied. [Aspect 9] The method according to embodiment 8, further comprising coupling the metal surface to a reference electrode and a counter electrode, each coupled to the potentiostat to form a circuit, and the metal surface acting as the working electrode of the treatment system. [Aspect 10] A system for treating infected metal implants, wherein the system is A device capable of applying a stimulating DC voltage that can destroy bacteria, A working electrode coupled to the device to which a stimulating voltage can be applied, the working electrode being a metal implant, Counter electrode and, A reference electrode, wherein each of the counter electrode and the reference electrode is coupled to the device to which the stimulation voltage can be applied, and forms an electrochemical circuit with the working electrode, A processor programmed to measure the transfer of accumulated charge to the metal implant over time in order to control the duration of treatment of the metal implant, the processor comparing the transfer of accumulated charge to the metal implant, measured in coulombs, with a predetermined threshold level stored by the processor, and programmed to terminate the treatment when the transfer of accumulated charge satisfies or exceeds the predetermined threshold level, A system for treating infected metal implants, including [specific component / tool]. [Aspect 11] The system according to embodiment 10, wherein the processor is further programmed to terminate the procedure when the accumulated charge transfer exceeds a predetermined threshold, or when the total procedure time exceeds a maximum stored procedure period, whichever occurs first. [Aspect 12] The system according to embodiment 10, wherein the processor is further programmed to display the degree of the treatment based on a measured percentage of accumulated charge transfer compared to a predetermined threshold. [Aspect 13] The system according to embodiment 10, wherein the processor is configured to sample the current at the working electrode at periodic time intervals and to sum the sampled currents in order to determine the stored charge transfer. [Aspect 14] The system according to embodiment 10, wherein the processor is configured to integrate current measured over a predetermined time interval in order to determine the stored charge transfer. [Aspect 15] The system according to embodiment 10, wherein the processor is located within the device to which the stimulation voltage can be applied. [Aspect 16] The system according to embodiment 10, wherein the metal implant is made from at least one of stainless steel, cobalt-chromium, and titanium. [Explanation of symbols] [Explanation of symbols]

[0039] List of parts in Figures 1-5 100 Treatment Systems 200 implants (working electrodes) 220 potentiostats 230 Reference electrode 240 counter electrodes 242 Conductor 244 Conductor 246 Conductor 247 Lead wire 248 Lead wires 250 processors 620 plots 640 plots 660 plots 680 plots

Claims

1. A system for treating infected metal implants, wherein the system is A device capable of applying a stimulating DC voltage that can destroy bacteria, A working electrode coupled to the device to which a stimulating voltage can be applied, the working electrode being a metal implant, Counter electrode and, A reference electrode, wherein each of the counter electrode and the reference electrode is coupled to the device to which the stimulation voltage can be applied, and forms an electrochemical circuit with the working electrode, A processor programmed to measure the transfer of accumulated charge to the metal implant over time in order to control the duration of treatment of the metal implant, the processor comparing the transfer of accumulated charge to the metal implant, measured in coulombs, with a predetermined threshold level stored by the processor, and programmed to terminate the treatment when the transfer of accumulated charge satisfies or exceeds the predetermined threshold level, Includes, A system for treating an infected metal implant, wherein the processor is further programmed to terminate the procedure when the accumulated charge transfer exceeds a predetermined threshold level, or when the total treatment time exceeds a maximum stored treatment period, whichever occurs first.

2. A system for treating an infected metal implant, wherein the system comprises: A device capable of applying a stimulating DC voltage that can destroy bacteria, A working electrode coupled to the device to which a stimulating voltage can be applied, the working electrode being a metal implant, Counter electrode and, A reference electrode, wherein each of the counter electrode and the reference electrode is coupled to the device to which the stimulation voltage can be applied, and forms an electrochemical circuit with the working electrode, A processor programmed to measure the transfer of accumulated charge to the metal implant over time in order to control the duration of treatment of the metal implant, the processor comparing the transfer of accumulated charge to the metal implant, measured in coulombs, with a predetermined threshold level stored by the processor, and programmed to terminate the treatment when the transfer of accumulated charge satisfies or exceeds the predetermined threshold level, Includes, A system for treating an infected metal implant, wherein the processor is further programmed to display the degree of the treatment based on a measured percentage of accumulated charge transfer compared to a predetermined threshold level.

3. The system according to claim 1 or 2, wherein the processor is configured to sample the current at the working electrode at periodic time intervals and to sum the sampled currents in order to determine the stored charge transfer.

4. The system according to claim 1 or 2, wherein the processor is configured to integrate current measured over a predetermined time interval in order to determine the stored charge transfer.

5. The system according to claim 1 or 2, wherein the processor is located within the device to which the stimulation voltage can be applied.

6. The system according to claim 1 or 2, wherein the metal implant is made from at least one of stainless steel, cobalt-chromium, and titanium.

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