System and apparatus for in-vivo assessment of relative position of an implant
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 includes a first assembly and a second assembly that 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.
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.
2. The apparatus of claim 1 , wherein the characterized frequency is the resonant frequency of the first assembly dependent on the 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.
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.