System, apparatus, and method for in-vivo assessment of relative position of an implant

• US 8,896,324 B2
• Filed: 09/26/2011
• Issued: 11/25/2014
• 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: Kroh, Jason, Cros, Florent, Courcimault, Christophe
• Primary Examiner(s): Nguyen, Vincent Q
• Application Number:
  US13/245,553
• Publication Number:
  US 20120016228A1
• Time in Patent Office: 1,156 Days
• Field of Search: 324/633, 324/635, 324/652, 324/655, 324/668, 324/675, 324/682, 600/424
• 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 method for providing an in-vivo assessment of relative movement of an implant that is positioned in a living being is provided wherein a first assembly and a second assembly are positioned within the living being. The first assembly includes 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. A method for providing an in-vivo assessment of relative movement of an implant in a living being, the method comprising:

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

positioning a second assembly within the living being spaced from the first assembly;

selectively electromagnetically coupling the first assembly to an ex-vivo source of RF energy; and

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

wherein the characterized frequency is the resonant frequency of the first assembly dependent on the distance between the first assembly and the second assembly.

2. The method of claim 1, wherein the second assembly comprises a metallic element.

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

4. The method of claim 3, wherein the non-metallic element exhibits magnetic properties.

5. The method of claim 1, wherein the second assembly comprises a passive electrical circuit.

6. The method of claim 5, wherein the passive electrical circuit of the second assembly comprises a passive electrical resonant circuit.

7. The method of claim 6, wherein the passive electrical resonant circuit of the second assembly is substantially identical to the passive electrical resonant circuit of the first assembly.

8. The method of claim 6, wherein the passive electrical resonant circuit of the second assembly comprises a LC resonant circuit.

9. The method of claim 8, wherein the passive electrical resonant circuit of the first assembly comprises a LC resonant circuit.

10. The method of claim 9, wherein a resonant frequency of the second assembly differs from a resonant frequency of the first assembly.

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

12. The method of claim 11, wherein the LC resonant circuit of the first assembly comprises a coil inductor operably coupled to a capacitor.

13. The method of claim 12, wherein the inductance of the LC resonant circuit is between about 5 to about 15 micro-Henry.

14. The method of claim 12, wherein the resonant frequency of the LC resonant circuit is between about 25 to about 45 MHz.

15. The method of claim 12, wherein the capacitance of the LC resonant circuit is between about 1 to about 20 pF.

16. The method of claim 12, wherein, at a first distance between the first assembly and the second assembly, the first assembly generates, in response to the electromagnetic coupling, 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 generates an output signal having a second frequency in response to the electromagnetic coupling that differs from the first frequency.

17. The method of claim 16, wherein the coil inductor is a substantially planar spiral inductor.

18. The method of claim 16, wherein the coil inductor has a longitudinal axis and wherein the coil inducted is elongated about the longitudinal axis.

19. The method of claim 16, wherein at least a portion of each winding of the coil inductor is non-planar with respect to the longitudinal axis.

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

21. The method of claim 20, wherein at least one of the first assembly and the second assembly is coupled to bone tissue proximate the implant.

22. The method of claim 21, wherein both the first assembly and the second assembly are coupled to spaced portions of the implant.

23. The method of claim 1, wherein a portion of the implant forms the second assembly.

24. The method of claim 23, wherein the portion of the implant forming the second assembly is metallic.

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

26. The method of claim 1, wherein the implant comprises an intervertebral cage.