Tissue extraction devices and methods

1. An electrosurgical tissue resecting probe comprising:

an elongated assembly comprising a windowed outer sleeve; and

a moveable inner resecting sleeve that provides window-open and window-closed configurations adapted to electrosurgically resect tissue disposed within the window; and

wherein an edge of the window at least partly comprises a dielectric material;

wherein the outer sleeve includes an interlocking structure that engages with a mating interlocking structure of the dielectric material.

2. The electrosurgical tissue resecting probe of claim 1 , wherein the outer sleeve comprises conductive material configured as a first polarity electrode.

3. The electrosurgical tissue resecting probe of claim 2 , wherein the inner resecting sleeve comprises conductive material configured as a second polarity electrode.

4. The electrosurgical tissue resecting probe of claim 1 , wherein the mating interlocking structure of the dielectric material includes keys that couple to the interlocking structure of the outer sleeve.

5. The electrosurgical tissue resecting probe of claim 4 , wherein the keys are configured to resist rotational displacement of the dielectric material relative the outer sleeve.

6. The electrosurgical tissue resecting probe of claim 4 , wherein the keys are configured to resist axial displacement of the dielectric material relative the outer sleeve.

7. The electrosurgical tissue resecting probe of claim 4 , wherein the keys are configured to resist radial outward displacement of the dielectric material relative the outer sleeve.

8. The electrosurgical tissue resecting probe of claim 4 , wherein the keys are configured to resist radial inward displacement of the dielectric material relative the outer sleeve.

9. The electrosurgical tissue resecting probe of claim 4 , wherein the dielectric material comprises at least one of a polymer, ceramic, or glass.

10. The electrosurgical tissue resecting probe of claim 4 , wherein the dielectric material has a comparative tracking index value ranging from 200 volts to 800 volts.

11. The electrosurgical tissue resecting probe of claim 1 , wherein the outer sleeve has a lumen with a dielectric surface layer.

12. The electrosurgical tissue resecting probe of claim 1 , wherein the dielectric surface layer has a thickness ranging from 0.001″ to 0.010″.

13. The electrosurgical tissue resecting probe of claim 1 , wherein an exterior surface of the outer sleeve is covered with a thin film of the dielectric material.

14. The electrosurgical tissue resecting probe of claim 13 , wherein an exterior surface portion of the outer sleeve not covered with the thin film of the dielectric material comprises a first polarity electrode.

15. The electrosurgical tissue resecting probe of claim 14 , wherein a distal portion of the inner resecting sleeve comprises a second polarity electrode.

16. The electrosurgical tissue resecting probe of claim 1 , wherein the inner resecting sleeve is moveable axially relative to the outer sleeve.

17. The electrosurgical tissue resecting probe of claim 1 , wherein the inner resecting sleeve is moveable axially and rotationally relative to the outer sleeve.

18. An electrosurgical tissue resecting probe comprising:

an elongated assembly extending along an axis comprising a windowed outer sleeve carrying an inner sleeve that is reciprocatable between window-open and window-closed positions, wherein the inner sleeve comprises a first polarity electrode and the outer sleeve comprises second polarity electrode; and

a thin-wall dielectric sleeve disposed around an exterior of the outer sleeve, the dielectric sleeve axially moveable to adjust the exposed surface area of the second electrode.

19. An electrosurgical tissue resecting probe comprising:

an elongated assembly including:

an outer sleeve having lumen and a tissue-receiving window opening into the lumen; and

an inner sleeve disposed within the lumen of the outer sleeve, the inner sleeve movable relative to the outer sleeve between a window-open position in which the tissue-receiving window is open and a window-closed position in which the tissue-receiving window is closed;

the inner sleeve including an electrode adapted to electrosurgically resect tissue disposed within the window as the inner sleeve moves from the window-open position to the window-closed position; and

wherein an edge of the tissue-receiving window at least partly comprises a dielectric material coupled with one or more interlocking features formed in the outer sleeve.

20. The electrosurgical tissue resecting probe of claim 19 , wherein an exterior surface of the outer sleeve is covered with a thin film of the dielectric material.

21. The electrosurgical tissue resecting probe of claim 19 , wherein an exterior surface portion of the outer sleeve not covered with the thin film of the dielectric material comprises a return electrode having a first polarity.

22. The electrosurgical tissue resecting probe of claim 21 , wherein the electrode of the inner sleeve is an active electrode having a second polarity opposite the first polarity.

23. The electrosurgical tissue resecting probe of claim 22 , wherein a length of a current path between the active electrode and the return electrode in any portion of travel of the inner sleeve between the window-open position to the window-closed position is within the range of 0.010 inches and 0.050 inches.

24. The electrosurgical tissue resecting probe of claim 19 , wherein the inner sleeve is movable axially relative to the outer sleeve.

25. The electrosurgical tissue resecting probe of claim 19 , wherein the inner sleeve is movable rotationally relative to the outer sleeve.

26. The electrosurgical tissue resecting probe of claim 19 , wherein the inner sleeve is movable axially and rotationally relative to the outer sleeve.