Surgical stapler with removable power pack

1. A surgical fastener applier comprising:

a housing containing a compartment therein;

an elongated member extending distally from the housing;

a first jaw and a second jaw adjacent a distal portion of the elongated member, at least the first jaw movable with respect to the second jaw to clamp tissue between the first and second jaws;

a fastener firing mechanism positioned within the housing, the firing mechanism movable between a first position and a second position, wherein in the second position, the firing mechanism effects firing of fasteners into the tissue clamped between the first and second jaws;

a cover on the housing openable to access the compartment within the housing; and

a power pack removably loadable into the compartment, the power pack having a battery, a motor and an a linear movable engagement member removably engageable with the firing mechanism when the power pack is loaded into the compartment, the power pack effecting movement of the firing mechanism from the first position to the second position, the firing mechanism movable linearly within the housing wherein actuation of the motor converts rotary motion to linear motion within the power pack to move the engagement member linearly to thereby move the firing mechanism linearly to the second position.

2. The surgical fastener applier of claim 1 , wherein the housing or the cover includes a first seal to seal about the cover in a closed position of the cover to protect the power pack positioned within the housing.

3. The surgical fastener applier of claim 1 , further comprising a second seal to block passage of body fluids from the elongated member into the compartment.

4. The surgical fastener applier of claim 1 , wherein the cover is hingedly connected to the housing.

5. The surgical fastener applier of claim 1 , wherein the power pack has a housing and one of the housing of the power pack or the compartment has at least one external rib and the other of the housing of the power pack or the compartment has at least one groove to receive the rib to guide the power pack within the compartment.

6. The surgical fastener applier of claim 1 , wherein the power pack includes a second engagement member, the second engagement member removably engageable with an articulation mechanism in the housing of the surgical fastener applier, the power pack effecting articulation of the first and second jaws from a linear position to a position angled with respect to a longitudinal axis of the elongated member.

7. The surgical fastener applier of claim 6 , wherein the power pack includes a second motor and the second motor effects linear movement of the articulation mechanism, and actuation of the second motor converts rotary motion to linear motion within the power pack to move the articulation mechanism in the housing linearly.

8. The surgical fastener applier of claim 1 , wherein the firing mechanism includes a firing rod, and the engagement member includes a yoke engageable with the firing rod.

9. The surgical fastener applier of claim 1 , wherein the power pack includes a gear mechanism powered by the motor, wherein rotation of a motor shaft of the motor effects rotation of the gear mechanism which effects linear movement of the firing mechanism of the surgical fastener applier.

10. The surgical fastener applier of claim 1 , wherein the power pack includes a drive belt powered by the motor, wherein rotation of a motor shaft of the motor effects rotation of a first disc which moves the drive belt to effect linear movement of the firing mechanism of the surgical fastener applier.

11. The surgical fastener applier of claim 10 , wherein the power pack includes a second disk, the second disk having a first diameter greater than a second diameter of the first disk, the second disk movable by the drive belt.

12. The surgical fastener applier of claim 1 , wherein the firing mechanism fires a plurality of rows of staples from one of the first and second jaws into contact with an anvil carried by the other of the first and second jaws.

13. The surgical fastener applier of claim 1 , further comprising a manually actuable jaw clamping mechanism actuable to move at least the first jaw toward the second jaw to clamp tissue between the first and second jaws.

14. The surgical fastener applier of claim 7 , wherein the power pack includes a second lead screw and second drive mechanism, and the second engagement member includes a yoke to engage a rod of the articulation mechanism.

15. The surgical fastener applier of claim 1 , wherein the power pack is contained in the compartment out of contact with body fluids of a patient, and the power pack is reusable.

16. The surgical fastener applier of claim 1 , wherein the power pack includes a lead screw and a drive with threads engageable with the lead screw for linear movement.

17. The surgical fastener applier of claim 16 , wherein the lead screw extends alongside the motor and is spaced therefrom.

18. The surgical fastener applier of claim 1 , wherein the power pack includes a sensor to indicate a position of the firing mechanism to indicate a status of fastener firing.

19. The surgical fastener applier of claim 1 , wherein the housing includes a sensor to indicate a position of the firing mechanism to indicate a status of fastener firing.

20. The surgical fastener applier of claim 1 , wherein one or both of the power pack or housing includes a sensor to indicate a position of articulation of the first and second jaws with respect to a longitudinal axis of the instrument.

21. The surgical fastener of claim 1 , wherein the power pack is removably loadable into the housing with the elongated member attached to the housing.