Surgical instrument with articulating tool assembly

1. A surgical instrument, comprising:

a handle portion including a movable handle, the movable handle being movable through an actuation stroke;

a body portion extending distally from the handle portion and defining a first longitudinal axis;

a disposable loading unit configured for releasable engagement with a distal end of the body portion and including:

a proximal body portion; and

an articulating tool assembly defining a second longitudinal axis and having a proximal end, the articulating tool assembly disposed at a distal end of the proximal body portion and being movable from a first position in which the second longitudinal axis is substantially aligned with the first longitudinal axis to at least a second position in which the second longitudinal axis is disposed at an angle with respect to the first longitudinal axis; and

an articulation mechanism including an articulation link for articulating the tool assembly, the articulation link having a slit at a proximal end thereof, an articulation knob operatively coupled to a cylindrical member that is operatively coupled to the slit of the articulation link, wherein rotational motion of the articulation knob is translated into axial motion of the articulation link thereby articulating the articulating tool assembly, wherein the articulation mechanism includes a plunger biased to engage the cylindrical member, wherein the engagement of the plunger with the cylindrical member allows for rotation of cylindrical member.

2. The surgical instrument according to claim 1 , wherein the articulation mechanism further includes an articulation spindle rotatably housed within a housing block, the articulation spindle including the cylindrical member and is coupled to the articulation knob so as to rotate therewith.

3. The surgical instrument according to claim 2 , wherein the housing block and the articulation spindle are adapted to limit a rotational range of the articulation spindle.

4. The surgical instrument according to claim 3 , wherein the housing block has a guide channel with a substantially arcuate shape, the guide channel receiving a member disposed on the articulation spindle.

5. The surgical instrument according to claim 4 , wherein length of the guide channel corresponds to a maximum desired articulation of the articulating tool tip.

6. The surgical instrument according to claim 2 , wherein the articulation spindle is configured to rotate in predetermined increments.

7. The surgical instrument according to claim 6 , wherein the articulation spindle defines a plurality of notches, the plurality of notches configured to mechanically interface with the plunger.

8. The surgical instrument according to claim 7 , wherein each of the plurality of notches indexes a rotational position of the articulation spindle with an articulation position of the articulating tool assembly.

9. The surgical instrument according to claim 8 , wherein at least one of the notches corresponds with a neutral axial plane position of the articulating tool assembly.

10. The surgical instrument according to claim 9 , wherein two of the notches correspond to maximum articulating positions of the articulating tool assembly.

11. The surgical instrument according to claim 10 , wherein the articulating tool assembly includes a cartridge assembly and an anvil assembly.