SYSTEM AND APPARATUS FOR IN-VIVO ASSESSMENT OF RELATIVE POSITION OF AN IMPLANT

• US 20090278553A1
• Filed: 04/01/2009
• Published: 11/12/2009
• Est. Priority Date: 09/16/2003
• Status: Active Grant

• Current Assignee: St. Jude Medical Luxembourg Holdings Ii S.A.R.L.
• Original Assignee: CardioMEMS Incorporated
• Inventors: Courcimault, Christophe, Cros, Florent, Kroh, Jason
• Granted Patent: US 8,026,729 B2
• Time in Patent Office: Days
• US Class Current: 324/633
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61B 5/4514 Cartilage
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

A system and apparatus for providing an in-vivo assessment of relative movement of an implant that is positioned in a living being is provided that comprises a first assembly and a second assembly that are positioned within the living being. The first assembly comprises a passive electrical resonant circuit that is configured to be selectively electromagnetically coupled to an ex-vivo source of RF energy and, in response to the electromagnetic coupling, generates an output signal characterized by a frequency that is dependent upon a distance between the first assembly and the second assembly at the time of the electromagnetic coupling.

Claims

1. An apparatus for providing an in-vivo assessment of relative movement of an implant in a living being, the apparatus comprising:

a first assembly positioned within the living being and comprising a passive electrical resonant circuit; and

a second assembly positioned within the living being and spaced therefrom the first assembly;

wherein the first assembly is configured to be selectively electromagnetically coupled to an ex-vivo source of RF energy and, in response to the electromagnetic coupling, to generate an output signal characterized by a frequency that is dependent upon a distance between the first assembly and the second assembly.

3. The apparatus of claim 1, wherein the second assembly comprises a metallic element.

4. The apparatus of claim 1, wherein the second assembly comprises a non-metallic element.

5. The apparatus of claim 4, wherein the non-metallic element exhibits magnetic properties.

6. The apparatus of claim 1, wherein the second assembly comprises a passive electrical circuit.

7. The apparatus of claim 6, wherein the passive electrical circuit of the second assembly comprises a passive electrical resonant circuit.

8. The apparatus of claim 7, wherein the passive electrical resonant circuit of the second assembly is substantially identical to the passive electrical resonant circuit of the first assembly.

9. The apparatus of claim 7, wherein the passive electrical resonant circuit of the second assembly comprises a LC resonant circuit.

10. The apparatus of claim 9, wherein the passive electrical resonant circuit of the first assembly comprises a LC resonant circuit.

11. The apparatus of claim 10, wherein a resonant frequency of the second assembly differs from a resonant frequency of the first assembly.

12. The apparatus of claim 1, wherein the passive electrical resonant circuit of the first assembly comprises a LC resonant circuit.

13. The apparatus of claim 12, wherein the LC resonant circuit of the first assembly comprises a coil inductor operably coupled to a capacitor.

14. The apparatus of claim 13, wherein the inductance of the LC resonant circuit is between about 5 to about 15 micro-Henry.

15. The apparatus of claim 13, wherein the resonant frequency of the LC resonant circuit is between about 25 to about 45 MHz.

16. The apparatus of claim 13, wherein the capacitance of the LC resonant circuit is between about 1 to about 20 pF.

17. The apparatus of claim 13, wherein, at a first distance between the first assembly and the second assembly, the first assembly is configured, in response to the electromagnetic coupling, to generate a first output signal having a first frequency, and wherein, at a second distance between the first assembly and the second assembly that differs from the first distance, the first assembly will generate an output signal having a second frequency in response to the electromagnetic coupling that differs from the first frequency.

18. The apparatus of claim 17, wherein the coil inductor is a substantially planar spiral inductor.

19. The apparatus of claim 17, wherein the coil inductor has a longitudinal axis and wherein the coil inducted is elongated about the longitudinal axis.

20. The apparatus of claim 17, wherein at least a portion of each winding of the coil inductor is non-planar with respect to the longitudinal axis.

21. The apparatus of claim 1, wherein at least one of the first assembly and the second assembly is coupled to a portion of the implant.

22. The apparatus of claim 21, wherein at least one of the first assembly and the second assembly is coupled to bone tissue proximate the implant.

23. The apparatus of claim 22, wherein both the first assembly and the second assembly are coupled to spaced portions of the implant.

24. The apparatus of claim 1, wherein a portion of the implant forms the second assembly.

25. The apparatus of claim 24, wherein the portion of the implant forming the second assembly is metallic.

26. The apparatus of claim 1, wherein the implant comprises a prosthetic device for preserving motion between adjacent bones.

2. The apparatus of claim 2, wherein the characterized frequency is the resonant frequency of the first assembly dependent on the distance between the first assembly and the second assembly.

27. A system for providing an in-vivo assessment of relative movement of an implant in a living being, the system comprising:

an ex-vivo source of RF energy;

a first assembly comprising a passive electrical resonant circuit positioned within the living being, wherein the first assembly is configured to be selectively electromagnetically coupled to the ex-vivo source of RF energy; and

a second assembly positioned within the living being and spaced therefrom the first assembly;

wherein the first assembly, in response to the electromagnetic coupling, is configured to generate an output signal characterized by a frequency that is dependent upon a distance between the first assembly and the second assembly.

28. The system of claim 27, wherein the second assembly is selected from a group consisting of:

a metallic element and a non-metallic element.

29. The system of claim 28, wherein the non-metallic element exhibits magnetic properties.

30. The system of claim 27, wherein the second assembly comprises an electrically resonant circuit.

31. The system of claim 27, wherein the second assembly comprises a passive electrically resonant circuit.

32. The system of claim 31, wherein the passive electrical resonant circuit of the second assembly is substantially identical to the passive electrical resonant circuit of the first assembly.

33. The system of claim 31, wherein the passive electrical resonant circuit of the second assembly comprises a LC resonant circuit.

34. The system of claim 33, wherein the passive electrical resonant circuit of the first assembly comprises a LC resonant circuit, and wherein a resonate frequency of the second assembly differs from a resonate frequency of the first assembly.

35. The system of claim 27, wherein the passive electrical resonant circuit of the first assembly comprises a LC resonant circuit.

36. The system of claim 35, wherein the LC resonant circuit of the first assembly comprises a coil inductor operably coupled to a capacitor.

37. The system of claim 27, wherein, at a first distance between the first assembly and the second assembly, the first assembly is configured, in response to the electromagnetic coupling, to generate a first frequency, and wherein, at a distance between the first assembly and the second assembly that differs from the first predetermined distance, the first assembly will generate an output signal having a second frequency in response to the electromagnetic coupling that differs from the first frequency.

38. The system of claim 37, further comprising a means for monitoring the output resonant frequency of the first assembly.

39. The system of claim 38, wherein the means for monitoring the output signal comprises a processor configured to determine the relative distance between the respective first and second assemblies based on the output signal.

40. The system of claim 39, wherein at least one of the first assembly and the second assembly is coupled to a portion of the implant.

41. The system of claim 40, wherein at least one of the first assembly and the second assembly is coupled to bone tissue proximate the implant.

42. The system of claim 39, wherein both the first assembly and the second assembly are coupled to spaced portions of the implant.

43. The system of claim 27, wherein a portion of the implant forms the second assembly.

44. The system of claim 43, wherein the portion of the implant forming the second assembly is metallic.

45. The system of claim 27, wherein the implant comprises a prosthetic device for preserving motion between adjacent bones.

46. The system of claim 27, wherein the implant comprises an intervertebral cage.