ARTIFICIAL JOINT

Abstract

The present invention relates to an artificial joint comprising a first joint portion (101), a second joint portion (105) and an intermediate portion (103). The first joint portion and the second joint portion each comprise an electrically conductive material and the intermediate portion comprises a non-conductive material and is arranged in between the first joint portion and the second joint portion such that the first joint portion is electrically isolated from the second joint portion. The artificial joint further comprises an internal electronic unit (110) provided inside of the isolating portion being connected to the first joint portion via at least one first electrode (111) and to the second joint portion via at least one second electrode (113). Thus, a first voltage can be applied to the first joint portion and a second electric voltage can be applied to the second joint portion, the voltages being with reference to a common reference potential.

Claims

1. An artificial joint (100) comprising a first joint portion (101), a second joint portion (105) and an intermediate portion (103) which are mechanically connected such that the first joint portion (101) is movable with respect to the second joint portion (105); wherein the first joint portion (101) and the second joint portion (105) each comprise an electrically conductive material and the intermediate portion (103) comprises a non-conductive material and is arranged in between the first joint portion (101) and the second joint portion (105) such that the first joint portion (101) is electrically isolated from the second joint portion (105); wherein: the artificial joint (100) further comprises an internal electronic unit (110) which is provided inside of the isolating portion (103) and is connected to the first joint portion (101) via at least one first electrode (111) and to the second joint portion (103) via at least one second electrode (113) such that a first electrical voltage can be applied to the first joint portion (101) and a second electric voltage can be applied to the second joint portion (105), whereby the first electrical voltage and the second electrical voltage are applied with reference to a common reference potential.

2. The artificial joint (100) according to claim 1, wherein the first electrode (111) is attached to an outer surface (112) of the intermediate portion (103), arranged essentially parallel to said outer surface (112) in between the intermediate portion (103) and the first joint portion (101) in electrical contact with a corresponding contact surface (102) of the first joint portion (101), thus electrically connecting the first joint portion (101) and the internal electronic unit (110) inside of the intermediate portion (103).

3. The artificial joint according to claim 1, wherein the artificial joint further comprises a central electrode (113) provided in between the first joint portion (101) and the second joint portion (105), whereby the internal electronic unit (110) is adapted to apply a third electrical voltage to the central electrode (113), whereby the third electrical voltage is applied with reference to the common reference potential.

4. The artificial joint according to claim 1, wherein the central electrode (113) is provided within an outer surface of the intermediate portion (103) in electrical contact with synovial fluid.

5. The artificial joint according to claim 1, wherein the first and second electrical voltages are applied such that the first joint portion (101) and the second joint portion (105) are set to the same polarity and the third electrical voltage is applied such that the central electrode is set to the opposing polarity.

6. The artificial joint according to claim 1, wherein the internal electronic unit (110) is adapted to communicate with an external control device (200), the external control device (200) thus being adapted to control an application of the first electrical voltage and the second electrical voltage, preferably and the third electrical voltage.

7. The artificial joint according to claim 1, wherein the internal electronic unit (110) is adapted to apply the first and the second electrical voltage such that a resulting electrical field strength ism between 0 V/cm and 60 V/cm.

8. The artificial joint according to claim 1, wherein the first electrical voltage is applied to the first joint portion (101) and the second electrical voltage is applied to the second joint portion, the first joint portion (101) and the second joint portion (105) are charged accordingly and a resulting electrical field is generally oriented from one of the first joint portion (101) and the second joint portion (105) to the other one of the first joint portion (101) and the second joint portion (105).

9. The artificial joint according to claim 1, wherein the internal electronic unit (110) is further provided with a transceiver (115) and the external control device (200) is provided with a transmitter (217) such that the external control device (200) is adapted to wirelessly control an application of the first electrical voltage and the second electrical voltage.

10. The artificial joint according to claim 1, wherein the artificial knee further comprises a transceiver coil (115) provided within the intermediate portion (103) in electrical connection with the internal electronic unit (110), and the external control device (200) is provided with a transmitter coil (217) such that electrical power necessary for applying the voltages can be provided from the external control device (200) to the internal electronic unit (110) through the transceiver coil (115) and the transmitter coil (217) by inductive power transmission.

11. The artificial joint according to claim 1, wherein the transceiver coil is provided embedded within an outer portion of the intermediate portion (103) surrounding the internal electronic unit (110).

12. The artificial joint according to claim 1, wherein the internal electronic unit (110) is further provided with at least one sensor (123, 125) which is provided in communication with the environment of the artificial joint and thus adapted to detect at least one of temperature of the synovial fluid, conductivity of the synovial fluid, pH of the synovial fluid or a marker of cell death within the synovial fluid.

13. The artificial joint according to claim 1, wherein the internal electronic unit (110) is adapted to communicate a signal received from the at least one sensor to the external control device (200) and the external control device is adapted to automatically adjust the first electrical voltage applied to the first conductive component (101) and the second electrical voltage applied to the second conductive component in response to the sensor signal.

14. The artificial joint according to claim 1, wherein the artificial joint is a knee prosthesis, the first joint portion (101) is a femoral portion, the second joint portion (105) is a tibial portion and the intermediate portion (103) is a polyethylene insert provided in between the femoral portion and the tibial portion.

15. A system (300) comprising the artificial joint (100) according to claim 1 and an external control device (200) adapted to control an application of the first electrical voltage and the second electrical voltage.

16. The artificial joint of claim 6, wherein the internal electronic unit (110) is adapted to communicate with an external control device (200), the external control device (200) thus being adapted to control an application of the first electrical voltage, the second electrical voltage, and the third electrical voltage.

17. The artificial joint of claim 7, wherein the internal electronic unit (110) is adapted to apply the first and the second electrical voltage such that a resulting electrical field strength is between 0 V/cm and 55 V/cm.

18. The artificial joint of claim 7, wherein the internal electronic unit (110) is adapted to apply the first and the second electrical voltage such that a resulting electrical field strength is between 0 V/cm and 40 V/cm.

19. The artificial joint of claim 7, wherein the internal electronic unit (110) is adapted to apply the first and the second electrical voltage such that a resulting electrical field strength is between 0 V/cm and 20 V/cm.

20. The artificial joint of claim 7, wherein the internal electronic unit (110) is adapted to apply the first and the second electrical voltage such that a resulting electrical field strength is between 10 V/cm and 20 V/cm.

Description

4. DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] In the following, the invention is described exemplarily with reference to the enclosed figures in which:

[0036] FIG. 1 shows a schematic view of an artificial joint;

[0037] FIG. 2 is a schematic illustration of the internal electronic unit and the external control device;

[0038] FIG. 3 shows a schematic cross-sectional view of the artificial knee;

[0039] FIG. 4 shows a schematic cross-section of a further embodiment of the artificial joint;

[0040] FIG. 5 illustrates an electric field distribution for an artificial joint;

[0041] FIG. 6 shows the electric field distribution for a further embodiment of the artificial joint; and

[0042] FIG. 7 illustrates a knee pad connected to an external control device housing a transmitter coil.

[0043] Even though the following embodiments are described using the example of an artificial knee, the skilled person will understand that the invention is applicable also to a different prosthesis such as to artificial hips, shoulders, a spine prosthesis, or the like.

[0044] FIG. 1 shows a schematic illustration of an artificial knee 100 which is an example of an artificial joint. As shown in the figure, the artificial knee 100 comprises a first joint portion 101 which in the shown case is a femoral portion 101, an intermediate portion 103 and a second joint portion 105 which in the shown case is a tibial portion 105. The intermediate portion 103 is formed of a non-conductive material such as a suitable plastic material as for example polyethylene and comprises a socket to which a cable 215 is attached connecting an internal electronic unit (not shown in this figure) to an external control device (also not shown).

[0045] FIG. 2 illustrates an example of a system comprising the artificial joint 100 and the external control device 200. As shown, the artificial joint 100 includes the intermediate portion 103 which houses the internal electronic unit 110. The internal electronic unit 110 is a unit, e.g. a small box, which in turn houses the electronic parts necessary for the electronic functions of the artificial joint 100. As shown, the internal electronic unit 110 is provided with a plurality of electrodes, in particular the first electrode 111, the second electrode 113 and the central electrode 114. If necessary, more electrodes may be provided which is illustrated by the electrode E.sub.N and all of the electrodes are connected to an electrode controller 109. Further, the internal electronic unit 110 is provided with sensors, in particular with a temperature sensor 123 and a pH sensor 125 which are controlled by a sensor controller 121. The internal electronic unit 110 is further provided with a transceiver 115 which in the shown case coincides with a receiver coil connected to a receiver controller 116. Thus, the receiver coil allows both for data communication with an external control device 200 as well as power reception via inductive power transmission from the external control device 200. As the skilled person will understand, alternatively, a transceiver can be provided being a separate component of the internal electronic unit 110. All of the components are connected to a power management unit 107 for management of the electric power necessary for applying the voltages and for the further electronic functions.

[0046] The internal electronic unit 110 can communicate with the external control device 200 either directly via cable 215 or through transceiver 115 wirelessly connected to a transmitter which in the shown example is a transmitter coil 217 of the external control device 200 connected to a corresponding transmitter controller 218. Also both connections can be provided as desired. The external control device receives electric power from an external power source 400 which is fed to a power controller 207. Using a transmitter controller 219, electric power can be fed from the external control device 200 to the internal electronic unit 110 either wirelessly via inductive power transmission through transmitter 217 and transceiver 115 or through cable 215. In turn, the external control device 200 can receive signals from the sensors 123, 125 which can be displayed using a screen 231 connected to a corresponding controller 230. The parameters can thus be read by a human operator, i.e. for example by a doctor who can interact with the external control device 200 making use for example of a keyboard 233. Using the keyboard, the operator can control functions of the internal electronic unit 110, for example can control the voltages applied through the electrodes 111, 113 and 114. Similarly, the system can provide for an automized feedback loop, i.e. in response to sensor signals transmitted by the internal electronic unit 110 to the external control device 200, the external control device can automatically respond by controlling the voltages applied through electrodes 111, 113 and 114.

[0047] FIG. 3 shows a cross-sectional view of the artificial knee 100. As shown, the internal electronic unit 110 is provided within the intermediate portion 103. The internal electronic unit 110 is electrically connected to a first electrode 111 via an electrical connection 141 (only one shown in the figure). As can be taken from this figure, the first electrode 111 is attached to an outer surface 112 of the intermediate portion 103 and is arranged essentially parallel to said outer surface, i.e. both surfaces are curved in the same way. This electrode is arranged in between the intermediate portion 103 and the first joint portion 101 and is in electrical contact with a corresponding contact surface 102 of the first joint portion 101. In this way, movement of the first joint portion 101 with respect to the second joint portion 105 is still possible. In other words, the first joint portion, i.e. the femoral portion of the artificial knee can be pivoted with respect to the tibial portion 105.

[0048] The internal electronic unit 110 is further provided with sensors out of which only sensor 123 is labeled in the figure. As the skilled person will take from the figure, the sensors are provided at the internal electronic unit 110 being in contact with the environment of the artificial joint such as with the synovial fluid in order to detect parameters such as e.g. temperature of the synovial fluid, pH of the synovial fluid, and/or conductivity of the synovial fluid or the like.

[0049] The internal electronic unit 110 is further electrically connected with the tibial portion 105 via electrical connection 143. In the figure a coil 115 is shown in a cross-sectional view which is a receiver coil for example for the reception of power via inductive power transmission from the external control device 200. As shown, the coil 115 is embedded within the intermediate portion 103 and thus advantageously secured against influences for example from synovial fluid surrounding the artificial knee.

[0050] The artificial knee is further provided with a socket 104 within the intermediate portion 103 which in the figure has received a plug 214 connected to a cable 215 for communication with the external control device 200.

[0051] FIG. 4 illustrates a further embodiment of the artificial joint 100′. As compared to the embodiment of the artificial joint 100 shown in FIG. 3, the artificial joint 100′ is provided with a central electrode 114 connected to the internal electronic unit 110 via electrical connection 145. As shown, the central electrode 114 is provided within an outer surface of the intermediate portion. The dashed lines indicate indicates that the electrode is located behind the section illustrated by the two-dimensional cross-sectional view. The central electrode 114 thus is in electrical contact with synovial fluid which may be present within cavity 500.

[0052] FIGS. 5 and 6 illustrate possible electrical field distributions. As shown in FIG. 5, by connecting a positive voltage to the femoral portion 101 and a negative voltage to the tibial portion 105, the electrical field as illustrated by the arrows in the left part of FIG. 5 is orientated essentially pointing from the femoral portion 101 to the tibial portion 105. As shown in the right part of FIG. 5, by setting the tibial portion to a positive polarity, and the femoral portion to a negative polarity, the electrical field as indicated by the arrows is essentially orientated from the tibial portion towards the femoral portion. In both cases as shown in FIG. 5, the central electrode is not used.

[0053] If it is desired to fine-tune the electrical field distribution, or even change the field distribution, the central electrode 114 can be applied as illustrated in FIG. 6. As shown, setting both the femoral and the tibial portion to a positive polarity, and the central electrode 114 to a negative polarity, the electrical field, as illustrated by the arrows in the left part of FIG. 6, points from the tibial portion and the femoral portion to the central electrode 114. In the opposing case in which the tibial portion and the femoral portion are set to a negative polarity and the central electrode 114 is set to a positive polarity, the electric field as illustrated by the arrows points from the central electrode 114 towards the tibial and the femoral portions.

[0054] As it will be clear for the person skilled in the art, in addition to these cases where the central electrode 114 is set to a polarity different from both the tibial portion and the femoral portion, it is also possible to set the central electrode 114 and one of the tibial or femoral portion to the same polarity which is different from the polarity of the other of the femoral or the tibial portion. Thus, even though by applying voltages to the first joint portion 101 and to the second joint portion 105, a global electrical field pointing from one of these portions to the other of these portions, can be achieved which is sufficient for achieving a repelling effect preventing adhesion of bacteria to the joint surfaces, the central electrode 114 allows for a plurality of field distributions. Thereby, it becomes possible to fine-tune the electrical field distribution, e.g. in accordance with geometrical requirements of the artificial joint in question.

[0055] FIG. 7 illustrates a system comprising the artificial joint 100 (not visible in the figure) and the external control device 200. In the shown embodiment, the transmitter coil (not visible in the figure) is provided outside of the external control device 200 connected therewith through an electrical connection 225. The transmitter coil is provided within a knee pad 700 attached to the knee of a patient 800 around the artificial joint 100. As indicated by the curved arrows in the figure, the transmitter coil generates magnetic fields through which the transmitter coil can communicate with the receiver coil (not visible in the figure) forming the transceiver of the internal electronic unit (not visible in the figure). Thus, it is possible that the external control device 200 feeds electrical power to the artificial joint 100 via inductive power transmission while at the same time, data communication between the internal electronic unit and the external control device is enabled. In other words, for example signals from sensors connected to the internal electronic unit can be communicated to the external control device 200 while the external control device 200 can communicate control signals to the internal electronic unit to control e.g. application of voltages or can control sensors.