Method and force-limiting handle mechanism for a surgical instrument

1. A handle assembly for use with a surgical instrument having an operative distal end portion comprising:

a handle housing;

a drive element movably mounted within the handle housing and connected to an operative distal end portion;

a drive assembly positioned within the handle housing and engageable with the drive element to move the drive element within the handle housing;

an actuator movably mounted on the handle housing; and

a force-limiting mechanism interposed between the drive assembly and the actuator, the force-limiting mechanism releasably connecting the actuator to the drive assembly, wherein a portion of the force-limiting mechanism is pivotably attached to the drive assembly about a pivot, and wherein the pivot is stationary with respect to the handle housing;

wherein the force-limiting mechanism includes a connecting rod having a first end connected to a portion of the drive assembly and a second end movably mounted within the actuator.

2. The handle assembly as recited in claim 1 , wherein the force-limiting mechanism includes a spring positioned within the actuator and adjacent the second end of the connecting rod.

3. The handle assembly as recited in claim 2 , wherein the force-limiting mechanism includes an adjustment screw positioned within the actuator and engageable with the spring to vary the force within the spring.

4. The handle assembly as recited in claim 1 , wherein the connecting rod has a protrusion and the drive assembly includes a cut out portion, the protrusion being releasably engageable within the cut out portion.

5. The handle assembly of claim 4 , wherein the protrusion extends laterally from the connecting rod.

6. The handle assembly of claim 1 , wherein the pivot is stationary with respect to a portion of the drive assembly that is pivotably attached to the force-limiting mechanism.

7. A handle assembly for use with a surgical instrument having an operative distal end portion comprising:

a handle housing;

a rack movably mounted within the handle housing and connected to an operative distal end portion;

a drive assembly positioned within the handle housing, the drive assembly including a pawl engageable with the rack;

a trigger pivotally mounted on the handle housing; and

an adjustable force-limiting mechanism releasably attached to a portion of the drive assembly and mounted for movement within the trigger, the adjustable force-limiting mechanism releasably connecting the trigger to the drive assembly, and wherein the adjustable force-limiting mechanism includes a connecting rod having a first end connected to a portion of the drive assembly and a second end movably mounted within the trigger.

8. The handle assembly as recited in claim 7 , wherein the adjustable force-limiting mechanism includes a spring mounted within the trigger such that a first end of the spring is engageable with the second end of the connecting rod.

9. The handle assembly as recited in claim 8 , wherein the adjustable force-limiting mechanism includes an adjustment screw mounted within the trigger such that rotation of the adjustment screw alters the pressure within the spring.

10. A method of controlling the maximum amount of force applied to an end effector by a handle assembly comprising:

providing a handle assembly having a handle housing, a rack movably mounted within the handle housing, a drive assembly mounted within the handle housing and engageable with the rack, a trigger pivotally mounted within the handle housing and a clutch mechanism interposed between the drive assembly and the trigger such that the clutch mechanism releasably connects the trigger to the drive assembly, wherein a portion of the clutch mechanism is pivotably attached to the drive assembly about a pivot, wherein a portion of the clutch mechanism is movably mounted within the trigger, and wherein the pivot is stationary with respect to the handle housing;

urging at least a portion of the clutch mechanism into engagement with the drive assembly by a predetermined force; and

releasing the clutch mechanism from the drive assembly in response to a predetermined amount of force applied to the rack.

11. The method as recited in claim 10 , wherein the step of urging at least a portion of the clutch mechanism includes urging a spring biased plunger associated with the clutch mechanism into engagement with the drive assembly.

12. A handle assembly for use with a surgical instrument having an operative distal end portion comprising:

a handle housing;

a rack movably mounted within the handle housing and connected to an operative distal end portion;

a drive assembly positioned within the handle housing, the drive assembly including a pawl engageable with the rack;

a trigger pivotally mounted on the handle housing; and

an adjustable force-limiting mechanism releasably attached to a portion of the drive assembly and mounted for movement within the trigger, the adjustable force-limiting mechanism releasably connecting the trigger to the drive, wherein a portion of the adjustable force-limiting mechanism is pivotably attached to the drive assembly about a pivot, wherein a portion of the adjustable force-limiting mechanism is movably mounted within the trigger, and wherein the pivot is stationary with respect to the handle housing.