Apparatus and method for assessing loads on adjacent bones

• US 6,706,005 B2
• Filed: 08/24/2001
• Issued: 03/16/2004
• Est. Priority Date: 08/25/2000
• Status: Expired due to Term

• Current Assignee: Cleveland Clinic Foundation
• Original Assignee: Cleveland Clinic Foundation
• Inventors: Benzel, Edward C., Ferrara, Lisa, Fleischman, Aaron J., Roy, Shuvo
• Primary Examiner(s): Hindenburg, Max F.
• Assistant Examiner(s): SZMAL, BRIAN SCOTT
• Application Number:
  US09/939,331
• Publication Number:
  US 20020049394A1
• Time in Patent Office: 935 Days
• Field of Search: 600/594, 600/587, 600/302, 600/300, 600/373, 600/377, 623/16, 623/17, 623/20, 623/17.11, 623/17.15, 623/17.16, 606/60, 606/102, 606/61, 128/899
• US Class Current: 600/594
• CPC Class Codes: A61B 17/7044 also having plates, staples or washers bearing on the vertebrae
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/0261 Strain gauges
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/036 by means introduced into body tracts A61B5/032 and A61B5/035 take precedence
• CPC Class Codes: A61B 5/4504 Bones A61B5/4547 takes precedence
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30563 having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/3067 for data transfer
• CPC Class Codes: A61F 2002/30772 Apertures or holes, e.g. of circular cross section
• CPC Class Codes: A61F 2002/3085 with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/4666 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61F 2250/0002 for data transfer

Abstract

An apparatus (10) that utilizes microelectromechanical systems (MEMS) technology to provide an in vivo assessment of loads on adjacent bones (24 and 26) comprises a body (34) for insertion between the adjacent bones. At least one sensor (42) is associated with the body (34). The sensor (42) generates an output signal in response to and indicative of a load being applied to the body (34) through the adjacent bones (24 and 26). A telemetric device (40) is operatively coupled with the sensor (42). The telemetric device (40) is operable to receive the output signal from the sensor (42) and to transmit an EMF signal dependent upon the output signal. According to various aspects of the invention, the sensor comprises a pressure sensor (42), a load cell (320), and/or at least one strain gauge (142).

Claims

1. An apparatus for providing an in vivo assessment of loads on adjacent bones, said apparatus comprising:

an implant that helps adjacent bones fuse together;

at least one sensor associated with said implant, said at least one sensor for generating an output signal in response to and indicative of a load being applied to said implant through the adjacent bones; and

at least one telemetric device operatively coupled with said at least one sensor, said at least one telemetric device being operable to receive said output signal from said at least one sensor and to transmit an EMF signal dependent upon said output signal.

2. The apparatus of claim 1 wherein said implant comprises a fusion cage for insertion between an adjacent pair of vertebrae, said fusion cage having an interior chamber for receiving bone graft material.

3. The apparatus of claim 1 wherein said at least one sensor comprises a pressure sensor.

4. The apparatus of claim 1 wherein said at least one sensor further comprises a load cell.

5. The apparatus of claim 1 further comprising at least one strain gauge mounted on said implant, said at least one strain gauge for generating a second output signal in response to a load being applied to said implant, said at least one strain gauge being electrically connected with said at least one telemetric device.

6. An apparatus for providing an in vivo assessment of loads on adjacent vertebrae to be fused together, the adjacent vertebrae being separated by an intervertebral space created by the removal of an intervertebral disc, said apparatus comprising:

a bone graft for insertion into the intervertebral space;

at least one sensor associated with said bone graft, said at least one sensor for generating an output signal in response to and indicative of a load being applied to said bone graft through the adjacent pair of vertebrae; and

at least one telemetric device operatively coupled with said at least one sensor, said at least one telemetric device being operable to receive said output signal from said at least one sensor and to transmit an EMF signal dependent upon said output signal.

7. The apparatus of claim 6 wherein said at least one sensor comprises a pressure sensor.

8. The apparatus of claim 7 wherein said pressure sensor is positioned in an interior portion of said bone graft.

9. The apparatus of claim 7 wherein said at least one sensor further comprises at least one load cell.

10. The apparatus of claim 9 wherein said at least one load cell is countersunk into a surface of said bone graft that faces one of the adjacent bones.

11. The apparatus of claim 6 wherein said at least one sensor comprises at least one load cell.

12. The apparatus of claim 6 further comprising:

an implant connected with the adjacent bones for helping to stabilize the adjacent bones while the adjacent bones fuse together; and

at least one strain gauge mounted on said implant, said at least one strain gauge for generating a second output signal in response to and indicative of a load being applied to said implant, said at least one strain gauge being electrically connected with said at least one telemetric device.

13. The apparatus of claim 12 wherein said at least one telemetric device is mounted on said implant and operatively coupled to said at least one sensor.

14. The apparatus of claim 12 wherein said at least one telemetric device and said at least one sensor are formed on a silicon substrate and secured within said bone graft, said at least one telemetric device being operatively coupled to said at least one strain gauge.

15. An apparatus for providing an in vivo assessment of loads on adjacent bones to be fused together, said apparatus comprising:

a bone graft for insertion between the adjacent bones;

a pressure sensor associated with said bone graft, said pressure sensor for generating a first output signal in response to and indicative of a load being applied to said bone graft through the adjacent bones; and

a load cell associated with said bone graft, said load cell for generating a second output signal in response to and indicative of the load being applied to said bone graft through the adjacent bones.

16. The apparatus of claim 15 wherein said pressure sensor is positioned in an interior portion of said bone graft.

17. The apparatus of claim 15 wherein said pressure sensor is coated with a film of biomolecules to protect said pressure sensor.

18. The apparatus of claim 15 wherein said pressure sensor is coated with monolayers of biomolecules to protect said pressure sensor.

19. The apparatus of claim 15 wherein said pressure sensor is coated with thin layers of biocompatible materials to protect said pressure sensor.

20. The apparatus of claim 15 wherein said load cell is countersunk into a surface of said bone graft that faces one of the adjacent bones.

21. The apparatus of claim 15 wherein said load cell is coated with a film of biomolecules to protect said load cell.

22. The apparatus of claim 15 wherein said load cell is coated with monolayers of biomolecules to protect said load cell.

23. The apparatus of claim 15 wherein said load cell is coated with thin layers of biocompatible materials to protect said load cell.

24. The apparatus of claim 15 further comprising at least one telemetric device operatively coupled with said pressure sensor and with said load cell, said at least one telemetric device being operable to receive said first and second output signals and to transmit EMF signals dependent upon said output signals.

25. The apparatus of claim 24 further comprising:

an implant connected with the adjacent bones for helping to stabilize the adjacent bones while the adjacent bones fuse together; and

at least one strain gauge mounted on said implant, said at least one strain gauge for generating a third output signal in response to and indicative of the load being applied to said implant, said at least one strain gauge being operatively coupled with said at least one telemetric device.

26. An apparatus for providing an in vivo assessment of loads on adjacent bones to be fused together, said apparatus comprising:

a graft for insertion between the adjacent bones;

at least one sensor associated with said graft, said at least one sensor for generating a first output signal in response to and indicative of a load being applied to said graft;

an implant connected with the adjacent bones for helping to stabilize the adjacent bones while the adjacent bones are fusing together; and

at least one strain gauge mounted on said implant, said at least one strain gauge for generating a second output signal in response to and indicative of the load being applied to said implant.

27. The apparatus of claim 26 wherein said at least one sensor comprises a pressure sensor.

28. The apparatus of claim 26 wherein said at least one sensor further comprises a load cell.

29. The apparatus of claim 26 wherein said implant includes a platform and at least one rod, said at least one strain gauge being mounted to one of said platform and said at least one rod.

30. The apparatus of claim 26 further comprising at least one telemetric device operatively coupled with said at least one sensor and with said at least one strain gauge, said at least one telemetric device being operable to receive said first and second output signals and to transmit EMF signals dependent upon said output signals percutaneously.

31. The apparatus of claim 30 further comprising an external monitoring unit for receiving said EMF signals transmitted percutaneously.

32. An apparatus for providing an in vivo assessment of loads on and motion of one or more bones, said apparatus comprising:

a member comprising a bone graft for placement adjacent a bone;

at least one sensor associated with said member, said at least one sensor for generating an output signal in response to and indicative of a load being applied to said member through the bone;

at least one telemetric device operatively coupled with said at least one sensor, said at least one telemetric device being operable to receive said output signal from said at least one sensor and including an antenna, operable to receive energy to power said at least one telemetric device and said at least one sensor from an external source and to transmit an EMF signal dependent upon said output signal.

33. The apparatus of claim 32 wherein said member further comprises an implant for helping adjacent bones fuse together.

34. A method for in vivo assessing the loads on adjacent vertebrae to be fused together, said method comprising the steps of:

harvesting a bone graft;

removing an intervertebral disc between the adjacent vertebrae;

instrumenting the bone graft with at least one sensor for sensing a load on the bone graft and for generating an output signal indicative of a sensed load;

operatively coupling at least one telemetric device with the at least one sensor to receive the output signal and to transmit an EMF signal dependent upon the output signal;

implanting the bone graft between the adjacent vertebrae; and

monitoring the EMF signal from the least one telemetric device.

35. The method of claim 34 further wherein said step of instrumenting the bone graft with at least one sensor comprises securing a pressure sensor to the bone graft.

36. The method of claim 34 further comprising the step of coating the pressure sensor with thin layers of a biocompatible material.

37. The method of claim 34 further comprising the step of coating the pressure sensor with monolayers of biomolecules.

38. The method of claim 34 further comprising the step of coating the pressure sensor with a film of biomolecules.

39. The method of claim 34 further wherein said step of instrumenting the bone graft with at least one sensor further comprises securing a load cell to the bone graft.

40. The method of claim 39 further comprising the step of coating the load cell with thin layers of a biocompatible material.

41. The method of claim 39 further comprising the step of coating the load cell with monolayers of biomolecules.

42. The method of claim 39 further comprising the step of coating the load cell with a film of biomolecules.

43. The method of claim 39 further comprising the step of attaching an implant to the adjacent vertebrae to help stabilize the vertebrae while fusing together.

44. The method of claim 43 further comprising the steps of:

mounting at least one strain gauge to the implant; and

operatively coupling the at least one strain gauge to the least one telemetric device.

45. The method of claim 34 further comprising the step of inductively energizing the at least one sensor and the least one telemetric device.

46. A method for in vivo assessing the loads on adjacent bones to be fused together, said method comprising the steps of:

providing a prosthetic implant for insertion between the adjacent bones to help the adjacent bones to fuse together;

instrumenting the implant with at least one sensor for sensing a load on the implant and for generating an output signal indicative of a sensed load;

operatively coupling at least one telemetric device with the at least one sensor to receive the output signal and to transmit an EMF signal dependent upon the output signal;

implanting the implant between the adjacent bones; and

monitoring the EMF signal from the least one telemetric device.

47. The method of claim 46 further comprising the step of filling the interior of the prosthetic implant with bone graft material following implantation of the prosthetic implant.

48. A method for in vivo assessing the loads on adjacent bones to be fused together, said method comprising the steps of:

harvesting a bone graft;

providing a body for insertion between the adjacent bones, the body comprising the harvested bone graft;

instrumenting the body with at least one sensor for sensing a load on the body and for generating an output signal indicative of a sensed load;

operatively coupling at least one telemetric device with the at least one sensor to receive the output signal and to transmit an EMF signal dependent upon the output signal;

implanting the body between the adjacent bones; and

monitoring the EMF signal from the least one telemetric device.

49. An apparatus for providing an in vivo assessment of loads on adjacent bones, said apparatus comprising:

a body comprising a bone graft for insertion between the adjacent bones;

at least one sensor associated with said body, said at least one sensor for generating an output signal in response to and indicative of a load being applied to said body through the adjacent bones; and

at least one telemetric device operatively coupled with said at least one sensor, said at least one telemetric device being operable to receive said output signal from said at least one sensor and to transmit an EMF signal dependent upon said output signal.

50. The apparatus of claim 49 wherein said body comprises an implant for helping the adjacent bones to fuse together.

51. The apparatus of claim 49 wherein said at least one sensor comprises a pressure sensor.

52. The apparatus of claim 51 wherein said at least one sensor further comprises a load cell.

53. The apparatus of claim 49 further comprising an implant connected with the adjacent bones for helping to stabilize the adjacent bones while the adjacent bones fuse together.

54. The apparatus of claim 53 further comprising at least one strain gauge mounted on said implant, said at least one strain gauge for generating a second output signal in response to a load being applied to said implant, said at least one strain gauge being electrically connected with said at least one telemetric device.

55. An apparatus for providing an in vivo assessment of loads on adjacent bones, said apparatus comprising:

a body for insertion between the adjacent bones;

at least one sensor associated with said body, said at least one sensor for generating an output signal in response to and indicative of a load being applied to said body through the adjacent bones;

at least one telemetric device operatively coupled with said at least one sensor, said at least one telemetric device being operable to receive said output signal from said at least one sensor and to transmit an EMF signal dependent upon said output signal; and

an implant connected with the adjacent bones for helping to stabilize the adjacent bones while the adjacent bones fuse together.

56. The apparatus of claim 55 wherein said body comprises a bone graft.

57. The apparatus of claim 55 wherein said at least one sensor comprises a pressure sensor.

58. The apparatus of claim 55 wherein said at least one sensor further comprises a load cell.

59. The apparatus of claim 55 further comprising at least one strain gauge mounted on said implant, said at least one strain gauge for generating a second output signal in response to a load being applied to said implant, said at least one strain gauge being electrically connected with said at least one telemetric device.