Pneumatically powered surgical cutting and fastening instrument with a variable control of the actuating rate of firing with mechanical power assist

1. A surgical instrument comprising:

a handle assembly;

a distal member distally coupled to said handle assembly and configured to support a surgical tool;

a pneumatically powered motor configured to generate at least one actuation motion upon receipt of at least one pneumatic signal from a source of pneumatic power fluidically coupled to said pneumatically powered motor;

a drive shaft assembly communicating with said pneumatically powered motor and the surgical tool for transmitting said at least one actuation motion to the surgical tool; and

a power assist trigger operably supported by said handle assembly: and

a linkage assembly comprising:

a first gear operably attached to said output shaft of said pneumatically powered motor;

a threaded shaft in threaded engagement with a portion of said power assist trigger such that when said power assist trigger is manually actuated, said threaded shaft is rotated; and

a second gear operably coupled to said threaded shaft and in threaded engagement with said first gear.

2. The surgical instrument of claim 1 wherein upon manual application of a first actuation force to said power assist trigger when said pneumatically powered motor is generating one of said actuation motions in the form of a firing motion, said linkage assembly transmits additional firing motion to said drive shaft assembly to enhance said firing motion and upon application of a second actuation force to said power assist trigger, said linkage assembly retards said firing motion generated by said pneumatically powered motor.

3. The surgical instrument of claim 1 further comprising an activation trigger configured to selectively control flow of gas from said source of pneumatic power to the pneumatically powered motor in proportion to an amount of manual force applied to said activation trigger.

4. The surgical instrument of claim 3 wherein said power assist trigger is pivotally supported relative to said handle assembly and wherein said activation trigger is pivotally supported relative to said handle assembly and is configured to pivotally travel with said power assist trigger.

5. A surgical instrument comprising:

a handle assembly;

a distal member distally coupled to said handle assembly and configured to support a surgical tool;

a pneumatically powered rotary motor configured to generate at least one actuation motion upon receipt of at least one pneumatic signal from a source of pneumatic power fluidically coupled to said pneumatically powered rotary motor, said pneumatically powered rotary motor having an output shaft coupled to a drive shaft assembly that operably interfaces with the surgical tool to transmit linear actuation motions to the surgical tool in response to said actuation motions from said pneumatically powered rotary motor;

a power assist trigger operably supported by said handle assembly and mechanically linked to said drive shaft assembly independent from said source of pneumatic power by a linkage assembly comprising:

a first gear operably attached to said output shaft of said pneumatically powered rotary motor;

a threaded shaft in threaded engagement with a portion of said power assist trigger such that when said power assist trigger is manually actuated, said threaded shaft is rotated; and

a second gear operably coupled to said threaded shaft and in threaded engagement with said first gear, such that upon manually actuating said power assist trigger, at least one non-pneumatically generated actuation motion is applied to said drive shaft assembly.

6. The surgical instrument of claim 5 wherein said pneumatically powered rotary motor is configured to selectively generate a firing motion that causes said drive shaft assembly to move in a first direction and a retraction motion that causes said drive shaft assembly to move in a second direction.

7. The surgical instrument of claim 6 wherein upon manual application of a first actuation force to said power assist trigger when said pneumatically powered motor is generating said firing motion, said linkage assembly transmits said additional firing motion to said drive shaft assembly to enhance said firing motion and upon a second actuation force to said power assist trigger, said linkage assembly retards said firing motion generated by said pneumatically powered motor.

8. The surgical instrument of claim 5 wherein said source of pneumatic power is supported by said handle assembly.

9. The method for processing an instrument for surgery, said method comprising:

obtaining said surgical instrument of claim 5 ;

sterilizing said surgical instrument; and

storing said instrument in a sterile container.