Articulating joint for surgical instruments

1. A surgical apparatus comprising:

an actuation mechanism comprising an actuation shaft operable from a proximal portion of the surgical apparatus;

a tool assembly pivotally positioned on a distal portion of the surgical apparatus at an articulation joint and being movable between a first position wherein the tool assembly is substantially aligned with a longitudinal axis of the surgical apparatus, and a second position wherein the tool assembly is pivoted away from the longitudinal axis of the surgical apparatus;

an articulation mechanism positionable to move the tool assembly between the first and second positions; and

a drive mechanism operably associated with the actuation mechanism, the drive mechanism including a first shaft operably engaged with a second shaft at the articulation joint, wherein the drive mechanism is configured to transfer rotational motion from the first shaft to the second shaft in the first and second positions of the tool assembly to cause at least the forming of staples in the tool assembly, wherein upon actuation of the actuation shaft, the first and second shafts are configured to rotate about the longitudinal axis in the same direction, the articulation joint allowing the first shaft to pivot with respect to the second shaft.

2. The surgical apparatus of claim 1 , wherein the first shaft includes a drive shaft having a first gear at a distal end thereof.

3. The surgical apparatus of claim 2 , further comprising an extension mechanism for moving the drive shaft distally as the tool assembly is moved from the first position.

4. The surgical apparatus of claim 3 , wherein the extension mechanism includes a spring engaged with a first portion and a second portion of the drive shaft.

5. The surgical apparatus of claim 2 , wherein the actuation mechanism include a movable handle and a gear attached to the drive shaft for rotation of the drive shaft.

6. The surgical apparatus of claim 2 , wherein the articulation joint includes the first gear and a second gear engaged with the first gear.

7. The surgical apparatus of claim 6 , wherein the second shaft includes a drive screw, the drive screw having the second gear at a proximal end thereof.

8. The surgical apparatus of claim 7 , further comprising a camming beam assembly threadably engaged with the drive screw.

9. The surgical apparatus of claim 8 , further comprising at least one cam wedge arranged for advancement by the camming beam.

10. The surgical apparatus of claim 6 , wherein the drive mechanism advances at least one cam wedge through a staple cartridge.

11. The surgical apparatus of claim 6 , wherein the first and second gears are substantially similar.

12. The surgical apparatus of claim 1 , wherein the actuation mechanism includes a motor.

13. The surgical apparatus of claim 1 , wherein the first shaft has a plurality of first teeth in a circular configuration and a plurality of second teeth in a circular configuration, the first teeth being engaged with the second teeth to transfer the rotation motion.

14. The surgical apparatus of claim 1 , wherein the tool assembly includes a surgical stapling cartridge.

15. The surgical apparatus of claim 1 , wherein the tool assembly includes a sled with one or more cam wedges.

16. The surgical apparatus of claim 1 , wherein the first shaft extends along the longitudinal axis of the surgical apparatus.

17. The surgical apparatus of claim 1 , wherein the first and second shafts extend along the longitudinal axis when the tool assembly is in a first position.

18. The surgical apparatus of claim 1 , wherein the rotational motion from the first shaft to the second shaft further causes the stapling of tissue.

19. The surgical apparatus of claim 1 , wherein the first shaft pivots relative to the second shaft during articulation of the tool assembly.

20. A surgical apparatus comprising:

an actuation mechanism operable from a proximal portion of the surgical apparatus;

a tool assembly pivotally positioned on a distal portion of the surgical apparatus at an articulation joint and being movable between a first position wherein the tool assembly is substantially aligned with a longitudinal axis of the surgical apparatus, and a second position wherein the tool assembly is pivoted away from the longitudinal axis of the surgical apparatus;

an articulation mechanism configured to move the tool assembly between the first and second positions; and

a drive mechanism operably associated with the actuation mechanism and configured to actuate the tool assembly, the drive mechanism including a first shaft having a first gear with a first plurality of teeth a second shaft having a second gear with a second plurality of teeth, wherein at least one of the first plurality of teeth of the first gear is in direct engagement with at least one of the second plurality of teeth of the second gear at the articulation joint, wherein the drive mechanism is configured to transfer rotational motion from the first shaft to the second shaft to cause at least the forming of staples in the tool assembly.

21. The surgical apparatus of claim 20 , wherein the drive mechanism transfers motion from the first shaft to the second shaft when the tool assembly is in a position other than the first position.

22. The surgical apparatus of claim 20 , wherein the rotational motion from the first shaft to the second shaft further causes the stapling of tissue.

23. The surgical apparatus of claim 20 , wherein the first shaft pivots relative to the second shaft during articulation of the tool assembly.