Articulating endoscopic surgical clip applier

1. An apparatus for application of surgical clips to body tissue, the apparatus comprising:

a handle assembly including:

a housing;

a drive assembly including:

a drive block axially and slidably supported in the housing, wherein the drive block defines a threaded lumen therethrough; and

a drive screw rotatably supported within the housing, the drive screw including a threaded surface configured for mating with the threaded lumen of the drive block;

a trigger operatively connected to the drive assembly such that actuation of the trigger acts on the drive block , wherein the trigger is pivotably connected to the drive block;

a ratchet mechanism supported in the housing, the ratchet mechanism including:

a pawl pivotably supported on the drive block;

a toothed-rack defined in the housing, the toothed-rack having a distal reversing recess and a proximal reversing recess configured for housing the pawl; and

a pawl spring supported on the drive block and configured to bias the pawl into operative engagement with at least one tooth of the toothed-rack to restrict longitudinal movement of the drive block in a second direction when the pawl is longitudinally translated in a first direction , wherein the first direction and the second direction are opposite directions;

wherein as the trigger is actuated, the drive block and the pawl are moved in the first direction causing the drive screw to rotate and the pawl to move from the distal reversing recess to the toothed-rack such that the trigger is restricted from returning to an un-actuated position until a complete stroke is achieved.

2. The apparatus according to claim 1 , further including a shaft assembly extending from the handle assembly, the shaft assembly including:

an end effector assembly having:

a plurality of clips loaded therein; and

jaws supported at a distal end of the end effector assembly, wherein the jaws are configured to serially receive and form a single clip at a time, of the plurality of clips.

3. The apparatus according to claim 2 , wherein the end effector assembly includes:

a pusher bar configured to load the single clip of the plurality of clips into the jaws; and

a drive bar configured to selectively engage the pusher bar to effectuate closure of the jaws.

4. The apparatus according to claim 3 , further comprising a rotatable drive member operatively connected to the trigger and to the end effector assembly, wherein actuation of the trigger results in rotation of the rotatable drive member, and rotation of the rotatable drive member results in loading of the single clip of the plurality of clips into the jaws and in a closing of the jaws.

5. The apparatus according to claim 4 , wherein the drive assembly further includes a clutch gear and a clutch bracket, the clutch gear defining a crown of gear teeth configured to cooperate and selectively engage a crown of teeth of the drive screw, the clutch bracket pivotally supported in the housing and including at least one leg extending around the clutch gear, the clutch bracket configured to approximate and separate the clutch gear and the crown of teeth of the drive screw.

6. The apparatus according to claim 5 , wherein the rotatable drive member includes the drive screw threadably engaged with the threaded lumen of the drive block, wherein axial translation of the drive block relative to the drive screw of the handle assembly results in rotation of the drive screw.

7. The apparatus according to claim 6 , wherein the end effector assembly includes a drive sled slidably and axially translatable therewithin and defines a helical lumen therethrough, and wherein the rotatable drive member includes an end effector drive screw threadably engaged with the helical lumen of the drive sled,

wherein rotation of the drive screw results in a rotation of the end effector drive screw and axial translation of the drive sled.

8. The apparatus according to claim 7 , wherein the drive sled is selectively engaged with the pusher bar such that distal advancement of the drive sled results in distal advancement of the pusher bar for a given distance and then the drive sled disconnects from the pusher bar after the given distance.

9. The apparatus according to claim 3 , wherein the pusher bar remains in a distally advanced position during approximation of the jaws.

10. The apparatus according to claim 3 , wherein the end effector assembly includes an advancer plate slidably disposed therewithin, wherein the advancer plate is detachably connected to the pusher bar,

wherein during distal advancement of the pusher bar, the pusher bar engages the advancer plate to distally move the advancer plate.

11. The apparatus according to claim 10 , wherein the advancer plate includes a tab extending therefrom for selective engagement by the pusher bar as the pusher bar is advanced distally.

12. A method for application of surgical clips to body tissue, the method comprising:

providing a surgical instrument including:

a housing;

a drive assembly having:

a drive block axially and slidably supported in the housing, wherein the drive block defines a threaded lumen therethrough; and

a drive screw rotatably supported within the housing, the drive screw including a threaded surface configured for mating with the threaded lumen of the drive block;

a trigger operatively connected to the drive assembly such that actuation of the trigger acts on the drive block, wherein the trigger is pivotably connected to the drive block;

a ratchet mechanism supported in the housing, the ratchet mechanism including:

a pawl pivotably supported on the drive block;

a toothed-rack defined in the housing, the toothed-rack having a distal reversing recess and a proximal reversing recess configured for housing the pawl; and

a pawl spring supported on the drive block and configured to bias the pawl into operative engagement with at least one tooth of the toothed-rack to restrict longitudinal movement of the drive block in a second direction when the pawl is longitudinally translated in a first direction, wherein the first direction and the second direction are opposite directions;

actuating the trigger such that the drive block and the pawl are translated in the first direction causing the drive screw to rotate and the pawl to move from the distal reversing recess to the toothed-rack of the ratchet mechanism; and

engaging the pawl with the toothed-rack of the ratchet mechanism such that the trigger is restricted from returning to an un-actuated position until a complete stroke is achieved.

13. The method according to claim 12 , wherein the surgical instrument provided further includes:

an end effector supporting jaws on a distal end thereof;

a pusher bar; and

a drive bar configured to selectively engage the pusher bar to effectuate closure of the jaws; and the method further comprises

translating the drive bar to selectively engage the pusher bar to effectuate closure of the jaws.

14. The method according to claim 13 wherein the surgical instrument provided further includes:

a rotatable drive member operatively connected to the trigger and the end effector; and the method further comprises

loading the end effector with a plurality of clips;

rotating the rotatable drive member; and

actuating the jaws to serially receive and form a single clip at a time, of the plurality of clips.