Surgical fastener applying apparatus including fluid-activated firing mechanism

1. A surgical fastener applying apparatus, comprising:

an end effector assembly movable between an open position and a closed position for grasping tissue therebetween, the end effector assembly configured to retain a plurality of surgical fasteners therein;

a fluid-actuated drive assembly including a piston configured to oscillate between a proximal position and a distal position; and

a drive beam configured for translation through the end effector assembly to eject the plurality of surgical fasteners therefrom,

wherein, the drive beam is incrementally advanced through the end effector assembly in response to oscillation of the piston from the proximal position to the distal position, and wherein the drive beam is retained in position as the piston oscillates from the distal position back to the proximal position.

2. The surgical fastener applying apparatus according to claim 1 , wherein a rack and pawl mechanism operably couples the piston and the drive beam such that the drive beam is incrementally advanced through the end effector assembly as the piston oscillates from the proximal position to the distal position, and such that the drive beam is retained in position as the piston oscillates from the distal position back to the proximal position.

3. The surgical fastener applying apparatus according to claim 2 , wherein the rack and pawl mechanism includes a rack coupled to the piston and a pawl coupled to the drive beam.

4. The surgical fastener applying apparatus according to claim 1 , further comprising a piston housing, wherein the piston is disposed within the piston housing, and wherein fluid pressure within the piston housing is configured to urge the piston through the piston housing from the proximal position to the distal position.

5. The surgical fastener applying apparatus according to claim 4 , wherein the piston is biased towards the proximal position such that, in the absence of sufficient fluid pressure within the piston housing, the piston is maintained in or returned to the proximal position.

6. The surgical fastener applying apparatus according to claim 1 , wherein the end effector assembly includes an anvil assembly and a cartridge assembly, at least one of the anvil assembly or the cartridge assembly movable relative to the other between the open position and the closed position.

7. The surgical fastener applying apparatus according to claim 6 , wherein the cartridge assembly is configured to retain the plurality of surgical fasteners therein, and wherein the drive beam is configured for translation through the cartridge assembly to eject the plurality of surgical fasteners therefrom.

8. The surgical fastener applying apparatus according to claim 1 , further comprising a retraction assembly coupled to the drive beam, the retraction assembly selectively actuatable for translating the drive beam proximally through the end effector assembly.

9. A surgical fastener applying apparatus, comprising:

an end effector assembly movable between an open position and a closed position for grasping tissue therebetween, the end effector assembly configured to retain a plurality of surgical fasteners therein;

a piston configured to oscillate between a proximal position and a distal position;

a drive beam configured for translation through the end effector assembly to eject the plurality of surgical fasteners therefrom; and

a rack and pawl mechanism operably coupling the piston and the drive beam such that the drive beam is incrementally advanced through the end effector assembly as the piston oscillates from the proximal position to the distal position, and such that the drive beam is retained in position as the piston oscillates from the distal position back to the proximal position.

10. The surgical fastener applying apparatus according to claim 9 , wherein the rack and pawl mechanism includes a rack coupled to the piston and a pawl coupled to the drive beam.

11. The surgical fastener applying apparatus according to claim 9 , further comprising a piston housing, wherein the piston is disposed within the piston housing, and wherein fluid pressure within the piston housing is configured to urge the piston through the piston housing from the proximal position to the distal position.

12. The surgical fastener applying apparatus according to claim 11 , wherein the piston is biased towards the proximal position such that, in the absence of sufficient fluid pressure within the piston housing, the piston is maintained in or returned to the proximal position.

13. The surgical fastener applying apparatus according to claim 9 , wherein the end effector assembly includes an anvil assembly and a cartridge assembly, at least one of the anvil assembly or the cartridge assembly movable relative to the other between the open position and the closed position.

14. The surgical fastener applying apparatus according to claim 13 , wherein the cartridge assembly is configured to retain the plurality of surgical fasteners therein, and wherein the drive beam is configured for translation through the cartridge assembly to eject the plurality of surgical fasteners therefrom.

15. The surgical fastener applying apparatus according to claim 9 , further comprising a retraction assembly coupled to the drive beam, the retraction assembly selectively actuatable for translating the drive beam proximally through the end effector assembly.

16. A surgical fastener applying apparatus, comprising:

a handle assembly;

an elongated member extending distally from the handle assembly and defining a distal end; and

a mechanism disposed at the distal end of the elongated member, the mechanism including:

an end effector assembly movable between an open position and a closed position for grasping tissue therebetween, the end effector assembly configured to retain a plurality of surgical fasteners therein;

a piston configured to oscillate between a proximal position and a distal position; and

a drive beam configured for translation through the end effector assembly to eject the plurality of surgical fasteners therefrom, wherein the drive beam is incrementally advanced through the end effector assembly in response to oscillation of the piston from the proximal position to the distal position, and wherein the drive beam is retained in position as the piston oscillates from the distal position back to the proximal position.

17. The surgical fastener applying apparatus according to claim 16 , wherein a rack and pawl mechanism operably couples the piston and the drive beam such that the drive beam is incrementally advanced through the end effector assembly as the piston moves from the proximal position to the distal position, and such that the drive beam is retained in position as the piston moves from the distal position back to the proximal position.

18. The surgical fastener applying apparatus according to claim 16 , wherein the mechanism further includes a piston housing, wherein the piston is disposed within the piston housing, and wherein fluid pressure within the piston housing is configured to urge the piston through the piston housing from the proximal position to the distal position.

19. The surgical fastener applying apparatus according to claim 18 , wherein the piston is biased towards the proximal position such that, in the absence of sufficient fluid pressure within the piston housing, the piston is maintained in or returned to the proximal position.

20. The surgical fastener applying apparatus according to claim 16 , further comprising a motor disposed within the handle assembly and configured to drive oscillation of the piston from the proximal position to the distal position.