Surgical instrument with articulating tool assembly

1. An articulation mechanism for articulating a surgical tool assembly, the articulation mechanism comprising:

a housing defining a longitudinal axis, the housing including a recessed portion having a first diameter, and a stepped portion having a second diameter;

an articulation spindle rotatably disposed within the housing and having an interface member, the articulation spindle including:

a cylindrical member having a bottom surface, the interface member extending downwardly from the bottom surface; and

a flange disposed on top of the cylindrical member and extending radially outward from the cylindrical member, wherein the cylindrical member mechanically interfaces with the recessed portion and the flange mechanically interfaces with the stepped portion; and

a first articulation link having a proximal and a distal end configured to be coupled to a proximal end of a second articulation link of a surgical tool assembly, the proximal end of the first articulation link defining a slit and the interface member movably received in the slit, wherein translational movement of the interface member through the slit effects an axial movement of the first articulation link and the slit thereof along the longitudinal axis.

2. The articulation mechanism according to claim 1 , wherein the stepped portion of the housing defines a guide channel therein having an arcuate shape, the articulation spindle having a guide member extending downwardly from the flange and configured for movable receipt in the guide channel.

3. The articulation mechanism according to claim 2 , wherein the guide channel has an arc length corresponding to a maximum rotation of the articulation spindle.

4. The articulation mechanism according to claim 1 , wherein the slit of the first articulation link defines an axis disposed perpendicular to the longitudinal axis of the housing, such that the interface member is configured to move perpendicular to the longitudinal axis of the housing.

5. The articulation mechanism according to claim 1 , further comprising a plunger disposed in the housing and biased to engage the articulation spindle.

6. The articulation mechanism according to claim 5 , wherein the articulation spindle includes a cylindrical outer surface having a plurality of notches defined therein, each notch of the plurality of notches configured to releasably receive the plunger.

7. The articulation mechanism according to claim 6 , wherein each of the plurality of notches is configured to index a rotational position of the articulation spindle with an articulation position of a surgical tool assembly.

8. The articulation mechanism according to claim 7 , wherein at least two of the plurality of notches corresponds to maximum articulating positions of a surgical tool assembly.

9. The articulation mechanism according to claim 6 , wherein the plunger extends perpendicularly relative to an outer circumferential surface of the articulation spindle.

10. The articulation mechanism according to claim 1 , wherein the housing and the articulation spindle are configured to limit a rotational range of the articulation spindle.

11. The articulation mechanism according to claim 1 , wherein the interface member is positioned off center on the bottom surface.

12. The articulation mechanism according to claim 1 , further comprising an articulation knob non-rotatably coupled to the articulation spindle for rotating the interface member.

13. The articulation mechanism according to claim 1 , further comprising a cap sensor axially movable within the housing, the cap sensor having a nub portion configured to be selectively received within a slot of the articulation spindle, wherein the cap sensor is axially movable between a distal position, in which the nub portion is received within the slot of the articulation spindle to resist rotation of the articulation spindle, and a proximal position, in which the nub portion of the cap sensor is disposed outside of the slot of the articulation spindle to allow the articulation spindle to rotate.

14. The articulation mechanism according to claim 1 , wherein the slit is enclosed.