Method and apparatus for cartilage reshaping by radiofrequency heating

• US 6,589,235 B2
• Filed: 01/19/2001
• Issued: 07/08/2003
• Est. Priority Date: 01/21/2000
• Status: Expired due to Term

• Current Assignee: Regents of the University of California (University of California), Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Regents of the University of California (University of California), Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Milner, Thomas E., Wong, Brian J. F., Keefe, Michael W., Sobol, Emil N.
• Primary Examiner(s): Dvorak, Linda C. M.
• Assistant Examiner(s): Schopfer, Kenneth G
• Application Number:
  US09/770,799
• Publication Number:
  US 20020016588A1
• Time in Patent Office: 900 Days
• Field of Search: 606/32, 606/34, 606/35, 606/41, 606/42, 607/96, 607/101, 607/102, 607/115, 607/148
• US Class Current: 606/32
• CPC Class Codes: A61B 18/14 Probes or electrodes therefor
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 5/4514 Cartilage

Abstract

A method and apparatus for reshaping cartilage using radiofrequency heating. The cartilage temperature is raised sufficiently for stress relaxation to occur in the cartilage, but low enough so that significant denaturation of the cartilage does not occur. The RF electrodes may be designed to also function as molds, preses, clamps, or mandrills to deform the cartilage tissue. Changes in various properties of the cartilage associated with stress relaxation in the cartilage may be measured in order to provide the control signal to provide effective reshaping without denaturation.

Claims

1. An apparatus to reshape cartilage comprising:

means for holding and deforming said cartilage to a desired final shape;

means for imparting RE energy to said cartilage in order to raise its temperature wherein stress relaxation occurs;

means for determining when said cartilage has reached the stress relaxation point; and

means to provide a feedback signal to said RE energy means to cease or reduce the RE energy input to said cartilage when the stress relaxation point has been reached.

2. The apparatus as recited in claim 1 wherein:

said stress relaxation determining means comprises means to monitor the temperature of said cartilage.

3. The apparatus as recited in claim 1 wherein:

said stress relaxation determining means comprises means to monitor cartilage physical properties selected from the group consisting of density, electrical resistance, and tissue acoustic properties.

4. The apparatus as recited in claim 1 wherein:

said stress relaxation determining means comprises means to measure changes in light scattering properties in said cartilage.

5. The apparatus as recited in claim 4 wherein said light scatter measurement means comprises:

a laser having wavelength selected from the visible to IR range and adapted to illuminate said cartilage; and

a means to detect and collect illuminating light scattered from said cartilage.

6. The apparatus as recited in claim 1 wherein:

the means for imparting RF energy, the means for determining, and the means to provide a feedback signal are adapted to heat said cartilage to a temperature in the range of 60 to 75 degrees C.

7. The apparatus as recited in claim 6 wherein:

the means for imparting RF energy, the means for determining, and the means to provide a feedback signal are adapted to heat said cartilage to a temperature of 70 degrees C.

8. The apparatus as recited in claim 1 wherein:

said RF energy means comprises one or more electrodes connected to an RF generator selected from the group consisting of bipolar and monopolar RF generators, with said electrode adapted to be in contact with said cartilage.

9. The apparatus as recited in claim 8 wherein:

said electrode adapted to make contact with said cartilage by insertion of said electrode.

10. The apparatus as recited in claim 9 wherein:

said electrode is needle or knife-blade shaped.

11. The apparatus as recited in claim 8 wherein:

said electrode is adapted to contact the surface of said cartilage.

12. The apparatus as recited in claim 11 wherein:

said electrode is shaped to provide the final desired shape.

13. The apparatus as recited in claim 11 wherein:

said electrode has a spatula or arc shape.

14. The apparatus as recited in claim 11 wherein:

said holding-deforming means is selected from the group consisting of jigs, molds, presses, mandrills, clamps and scissors that integrates said electrode and is adapted to also deform said cartilage.

15. The apparatus as recited in claim 14 wherein;

said electrode is made from a shape memory alloy.

16. The apparatus as recited in claim 8 wherein:

said electrodes comprise an array of electrodes adapted to be in contact with said cartilage.

17. The apparatus as recited in claim 16 wherein:

said electrodes are activated either sequentially or in parallel.

18. The apparatus as recited in claim 1 wherein:

the frequency of said RF energy is selected from the range of on the order of ½

MHz to on the order of several MHz.

19. The apparatus as recited in claim 18 wherein:

the frequency is selected dynamically according to the feedback control signal(s).

20. The apparatus as recited in claim 8 wherein:

said electrodes are embedded in a non-conductive biocompatible material.

21. A method to reshape cartilage comprising the steps of:

holding and deforming said cartilage to a desired final shape;

imparting RE energy to said cartilage in order to raise its temperature wherein stress relaxation occurs;

determining when said cartilage has reached the stress relaxation point; and

providing a feedback signal to said RE energy means to cease or reduce the RF energy input to said cartilage when the stress relaxation point has been reached.

22. The method as recited in claim 21 wherein:

said stress relaxation determining step comprises monitoring the temperature of said cartilage.

23. The method as recited in claim 21 wherein:

said stress relaxation determining step comprises monitoring cartilage physical properties selected from the group consisting of density, electrical resistance, and tissue acoustic properties.

24. The method as recited in claim 21 wherein:

said stress relaxation determining step comprises measuring changes in light scattering properties in said cartilage.

25. The method as recited in claim 24 wherein:

said step of measuring changes in light scattering properties comprises illuminating said cartilage with a laser having wavelength selected from the visible to IR range, and detecting and collecting the illuminating light scattered from said cartilage.

26. The method as recited in claim 21 wherein:

said steps of imparting, determining, and providing achieve a step of heating said cartilage to a temperature in the range of 60 to 75 degrees C.

27. The method as recited in claim 26 wherein:

said steps of imparting, determining, and providing achieve a step of heating said cartilage to a temperature of 70 degrees C.

28. The method as recited in claim 21 wherein said RF energy imparting step further comprises:

utilizing one or more electrodes connected to an RF generator selected from the group consisting of bipolar and monopolar RF generators; and

contacting said cartilage with said electrode.

29. The method as recited in claim 28 wherein said step of contacting further comprises inserting said electrode.

30. The method as recited in claim 29 wherein said step of imparting and utilizing further comprise:

providing said electrode in a shape of a needle or a knife-blade.

31. The method as recited in claim 28 wherein said step of contacting further comprises:

placing said electrode in contact with the surface of said cartilage.

32. The method as recited in claim 31 further comprising:

providing said electrode in the desired shape.

33. The method as recited in claim 31 further comprising:

providing said electrode in a spatula or arc shape.

34. The method as recited in claim 31 wherein said holding and deforming step further comprises:

utilizing an implement selected from the group consisting of jigs, molds, presses, mandrills, clamps and scissors; and

integrating said electrode to deform said cartilage.

35. The apparatus as recited in claim 34 further comprising;

providing said electrode made from a shape memory alloy.

36. The apparatus as recited in claim 28 wherein:

said step of utilizing comprises utilizing an array of electrodes; and

said step of contacting comprises contacting said cartilage with said array of electrodes.

37. The apparatus as recited in claim 36 further comprising:

activating said electrodes either sequentially or in parallel.

38. The method as recited in claim 21 further comprising:

selecting the frequency of said RF energy from the range of on the order of ½

MHz to on the order of several MHz.

39. The method as recited in claim 38 further comprising:

selecting the frequency dynamically according to the feedback control signal(s).