Impulsive percussion instruments for endplate preparation

• US 7,569,057 B2
• Filed: 09/09/2004
• Issued: 08/04/2009
• Est. Priority Date: 09/11/2003
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Inventors: Josse, Loic, Liu, Mingyan
• Primary Examiner(s): Robert; Eduardo C
• Assistant Examiner(s): George; Tara R
• Application Number:
  US10/937,159
• Publication Number:
  US 20050065529A1
• Time in Patent Office: 1,790 Days
• Field of Search: 606/79, 606/80, 606 83- 86, 606/171, 606/168, 606/173, 606/182, 30392-394, 301/82, 301/86, 301/87, 302/09, 302/10, 30216-220
• US Class Current: 606/79
• CPC Class Codes: A61B 17/025 Joint distractors
• CPC Class Codes: A61B 17/1604 Chisels; Rongeurs; Punches; Stamps
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 2017/0256 for the spine

Abstract

A hand-held instrument, with a rotary power input to a camshaft, has cam and follower arrangement to provide a reciprocating shaft output. A cutter is provided on the output shaft. In one example, rotating cam percussion is transmitted to the cutter by engaging the cutter with the tissue to be cut, and pushing the instrument forward toward the cutter. In another example, rotating cam percussion is transmitted to the cutter by engaging the cutter with the tissue to be cut, and pulling the instrument back toward the user while maintaining engagement of the cutter with the tissue. In both examples, the cutter remains in idle condition until an axially directed load, forward in the one example, or backward on the other example, is placed on the cutter by moving the instrument forward or backward, respectively, while the camshaft is rotating. A distractor with frame is used to spread and maintain space between vertebral bodies, enabling entrance of the cutter.

Claims

1. A powered, hand-held instrument for treating vertebral endplates, comprising:

a body configured to be held in a surgeon'"'"'s hand;

a camshaft rotatable about a rotational axis in said body and having a cam surface rotatable about said rotational axis;

a cutter shaft having a proximal end and a distal end, said cutter shaft extending along a longitudinal axis and being mounted in said body to reciprocate in forward and reverse directions along said longitudinal axis;

a cutter disposed at said distal end of said cutter shaft and configured to have a preferred performance direction in one of said forward and reverse directions;

said cutter shaft being moveable in said preferred performance direction by said cam surface when said camshaft is rotating;

a cutter drive shaft having a proximal end and a distal end, said cutter drive shaft having a first connector at said distal end and a cam follower surface adjacent said proximal end and facing said cam surface;

said cutter engaged to said cutter shaft and having a reverse preferred performance direction, said cutter shaft having a second connector at said proximal end of said cutter shaft, said second connector connected to the first connector to transmit axial force between said cutter drive shaft and said cutter shaft; and

means for normally disabling movement of said cutter shaft by said camshaft, said means for disabling being a compression spring bearing on said body and on a portion of said cutter drive shaft to urge said cam follower surface in a reverse direction away from said cam surface.

2. The instrument of claim 1 and wherein:

said proximal end portion of said cutter drive shaft includes a ring portion encircling said camshaft and having said cam follower surface facing an inner surface of said ring.

3. The instrument of claim 2 and wherein:

said ring portion has a spring seat shoulder thereon; and

said spring bearing on said spring seat shoulder to urge said cutter drive shaft in a reverse direction to displace said cam follower surface away from said cam surface of said camshaft.

4. A powered, hand-held instrument for treating vertebral endplates, comprising:

a body configured to be held in a surgeon'"'"'s hand;

a camshaft rotatable about a rotational axis in said body and having a cam surface rotatable about said rotational axis;

a cutter shaft having a proximal end and a distal end, said cutter shaft extending along a longitudinal axis and being mounted in said body to reciprocate in forward and reverse directions along said longitudinal axis;

a screw secured in said body and oriented transverse to said longitudinal axis; and

an elongate hole in said cutter shaft configured to receive said screw therethrough for limiting said travel of said cutter shaft in both of said forward and reverse directions;

a cutter disposed at said distal end of said cutter shaft and configured to have a preferred performance direction in one of said forward and reverse directions;

said cutter shaft being moveable in said preferred performance direction by said cam surface when said camshaft is rotating; and

means on said body for normally disabling movement of said cutter shaft by said camshaft.

5. The instrument of claim 4 and wherein:

said means for disabling is arranged to be neutralized by manual force applied to said body in said preferred performance direction.

6. The instrument of claim 4 and wherein:

said cutter shaft has a cam follower surface facing said cam surface; and

said means for disabling comprise a compressed spring bearing on said body and on said cutter shaft to urge said cam follower away from said cam surface.

7. The instrument of claim 4 and wherein:

said means for disabling comprise a resilient member normally urging said cutter shaft in said preferred performance direction.

8. The instrument of claim 7 and wherein:

said resilient member comprises a compressed coil spring.

9. The instrument of claim 4 and further comprising:

a cutter drive shaft having a longitudinal axis and having a proximal end and a distal end, said cutter drive shaft having a cam follower surface adjacent said proximal end and facing said cam surface;

said cutter drive shaft having an elongate hole extending axially rearward from said distal end of said cutter drive shaft;

said cutter shaft having an elongate stem received in said elongate hole in said cutter drive shaft;

said cutter drive shaft having a second hole transverse to said cutter drive shaft axis; and

a second screw extending into said second hole and threadable into said cutter shaft to retain said cutter shaft in said cutter drive shaft.

10. The instrument of claim 9 and wherein:

said second screw has a head disposed in said second hole and abuttingly engageable with a wall of said second hole to limit relative axial movement between said cutter shaft and said cutter drive shaft.

11. The instrument of claim 4 wherein said longitudinal axis is arranged transverse to said rotational axis.

12. An instrument for cutting bodily tissue, comprising:

an instrument body;

a camshaft mounted to said body and having a rotary power source input adapter for rotation of said camshaft about a rotational axis, said camshaft having a cam surface with locations thereon arranged at different radial distances from said rotational axis;

a cutter shaft mounted to said body for reciprocation therein, and having a proximal end and a distal end;

a cutter engaged with said cutter shaft adjacent said distal end; and

a cam follower having a cam follower surface operable to displace said cutter when engaged with said cam surface during rotation of said camshaft; and

a cutter drive shaft having a proximal end and a distal end, said cutter drive shaft having a first connector at said distal end and defining said cam follower surface adjacent said proximal end and facing said cam surface;

said cutter engaged to said cutter shaft and having a reverse preferred performance direction, said cutter shaft having a second connector at said proximal end of said cutter shaft, said second connector connected to the first connector to transmit axial force between said cutter drive shaft and said cutter shaft; and

wherein said cam surface is normally disengaged from said cam follower surface but is operably engagable with said cam follower surface during rotation of said cam shaft for impact driving said cutter in a first direction.

13. The instrument of claim 12 and further comprising:

means for normally disengaging said cam follower surface from said cam surface.

14. The instrument of claim 13 and wherein:

said means for normally disengaging is a spring.

15. The instrument of claim 14 and wherein:

said spring is a return spring effecting return of said cam follower surface opposite said first direction of impact driving said cutter, said spring normally applying a return force to hold said cam follower surface away from said rotating cam surface.

16. The instrument of claim 14 and wherein:

said spring is a compression spring having a proximal end seated in a fixed location in said body, and having a distal end engaging a shoulder on said cutter shaft and urging said cutter shaft in a forward direction.

17. The instrument of claim 14 and wherein:

said spring is a compression spring having a distal end seated at a constant location in said body and having a proximal end engaging a shoulder on said cutter shaft and urging said cutter shaft in a reverse direction to normally maintain said cam follower surface spaced from said cam surface.

18. A powered instrument for surgical use, comprising:

a body having a cam housing portion and a shaft housing portion;

a camshaft mounted for rotation in said body about a rotational axis and having a cam in said cam housing portion, said cam having a cam surface extending about the rotational axis at non-uniform radial distances from the rotational axis;

shafting extending along a longitudinal axis and mounted for reciprocation in said shaft housing portion of said body along said longitudinal axis, said shafting having a proximal end portion having a cam follower surface engageable with said cam, said shafting having a distal end portion including a cutter, said shafting comprising a cutter drive shaft and a cutter shaft;

said cutter drive shaft having a proximal end portion defining said cam follower surface and a distal end portion;

said cutter shaft having a proximal end portion and a distal end portion including said cutter; and

a connector selectively engaged between said distal end portion of said cutter drive shaft and said proximal end portion of said cutter shaft to selectively maintain a connection between said cutter drive shaft and said cutter shaft; and

wherein said shaft housing portion includes a wall defining an opening extending transversely therethrough, said opening positioned in general alignment with said connector to provide access to said connector to allow selective disengagement of said connector from between said distal end portion of said cutter drive shaft and said proximal end portion of said cutter shaft and disconnection of said cutter shaft from said cutter drive shaft; and

wherein said connector is positioned within aligned openings in said distal end portion of said cutter drive shaft and said proximal end portion of said cutter shaft to maintain said connection between said cutter drive shaft and said cutter shaft.

19. The instrument of claim 18 and further comprising:

a rotary motor connected to said camshaft for rotating said camshaft.

20. The instrument of claim 19 and further comprising:

a controllable source of energy coupled to said rotary motor for energizing said rotary motor and controlling power applied to said rotary motor.

21. The instrument of claim 18 wherein said longitudinal axis is arranged transverse to said rotational axis.

22. The instrument of claim 18, further comprising a spring positioned in a spring housing portion of said body, said spring providing a biasing force to said shafting in a direction of said longitudinal axis toward said cutter to bias said cam follower surface of said shafting away from said cam surface to a disengaged position wherein said shafting is normally disengaged from said cam surface.

23. The instrument of claim 18, wherein said distal end portion of said cutter drive shaft and said proximal end portion of said cutter shaft include connection portions, said connection portions including an axial stem received within an axial bore to connect said cutter shaft to said cutter drive shaft.

24. The instrument of claim 23, wherein said distal end portion of said cutter drive shaft includes said axial bore and said proximal end portion of said cutter shaft includes said axial stem.

25. The instrument of claim 18, wherein said connector comprises a screw, and wherein one of said aligned openings is threaded, said screw threadedly engaged within said threaded opening to maintain said connection between said cutter drive shaft and said cutter shaft.

26. The instrument of claim 18, wherein said connector is positioned entirely within said shaft housing portion of said body.

27. The instrument of claim 18, wherein said connector comprises a screw having a threaded portion and a head portion, wherein one of said aligned openings is threaded, said threaded portion of said screw threadedly engaged within said threaded opening to maintain said connection between said cutter drive shaft and said cutter shaft, said head portion of said screw inwardly recessed from an inner wall of said shaft housing portion.

28. The instrument of claim 18, wherein said opening in said wall of said shaft housing portion comprises an elongate slot extending along said longitudinal axis.

29. The instrument of claim 18, further comprising a plurality of said cutter shafts, each of said plurality of cutter shafts having a different configuration of said cutter.

30. The instrument of claim 18, wherein said cutter shaft is slidably displaced along an axial bore defined by said shaft housing portion of said body.

31. A powered instrument for surgical use, comprising:

a body;

a camshaft mounted for rotation in said body about a rotational axis and including a cam having a cam surface extending about said rotational axis at non-uniform distances from the rotational axis;

shafting extending along a longitudinal axis and mounted for reciprocation in a shaft housing portion of said body along said longitudinal axis, said shafting having a proximal end portion having a cam follower surface engageable with said cam, said shafting having a distal end portion including a cutter, said rotational axis arranged transverse to said longitudinal axis of said shafting, said shafting comprising a cutter drive shaft and a cutter shaft;

said cutter drive shaft having a proximal end portion defining said cam follower surface and a distal end portion;

said cutter shaft having a proximal end portion and a distal end portion including said cutter; and

a connector selectively engaged between said distal end portion of said cutter drive shaft and said proximal end portion of said cutter shaft to selectively maintain a connection between said cutter drive shaft and said cutter shaft; and

wherein said shaft housing portion includes a wall defining an opening extending transversely therethrough, said opening positioned in general alignment with said connector to provide access to said connector to allow selective disengagement of said connector from between said distal end portion of said cutter drive shaft and said proximal end portion of said cutter shaft and disconnection of said cutter shaft from said cutter drive shaft; and

wherein said connector is positioned within aligned openings in said distal end portion of said cutter drive shaft and said proximal end portion of said cutter shaft to maintain said connection between said cutter drive shaft and said cutter shaft.

32. The instrument of claim 31 and further comprising:

a spring in a spring housing portion of said body and normally holding said cam follower surface of said shafting disengaged from said cam surface.

33. The instrument of claim 31 and further comprising:

a rotary motor connected to said camshaft for rotating said camshaft about said rotational axis.

34. The instrument of claim 31, wherein said distal end portion of said cutter drive shaft and said proximal end portion of said cutter shaft include connection portions, said connection portions including an axial stem received within an axial bore to connect said cutter shaft to said cutter drive shaft.

35. The instrument of claim 34, wherein said distal end portion of said cutter drive shaft includes said axial bore and said proximal end portion of said cutter shaft includes said axial stem.

36. The instrument of claim 31, wherein said connector comprises a screw, and wherein one of said aligned openings is threaded, said screw threadedly engaged within said threaded opening to maintain said connection between said cutter drive shaft and said cutter shaft.

37. The instrument of claim 31, wherein said connector is positioned entirely within said shaft housing portion of said body.

38. The instrument of claim 31, wherein said connector comprises a screw having a threaded portion and a head portion, wherein one of said aligned openings is threaded, said threaded portion of said screw threadedly engaged within said threaded opening to maintain said connection between said cutter drive shaft and said cutter shaft, said head portion of said screw inwardly recessed from an inner wall of said shaft housing portion.

39. The instrument of claim 31, wherein said opening in said wall of said shaft housing portion comprises an elongate slot extending along said longitudinal axis.

40. The instrument of claim 31, further comprising a plurality of said cutter shafts, each of said plurality of cutter shafts having a different configuration of said cutter.

41. The instrument of claim 31, wherein said cutter shaft is slidably displaced along an axial bore defined by said shaft housing portion of said body.