Needlescopic scissor end effector and methods of use

1. A scissors end effector assembly comprising:

a top shear;

a bottom shear;

a cam tube extending in a longitudinal direction, the cam tube having a proximal end and a distal end;

a clevis attached to the distal end of the cam tube, the clevis including an upper arm and a lower arm; and

a cam bushing defining an upper slot having a periphery surrounding and slidably receiving the upper arm, and a lower slot having a periphery surrounding and slidably receiving the lower arm,

wherein the top shear and the bottom shear are pivotally mounted between the upper arm and the lower arm such that the top shear and the bottom shear open and close via force or bias from the cam bushing.

2. The scissors end effector assembly of claim 1 , further comprising:

a cannula defining an interior lumen, the cannula having a proximal end and a distal end; and

a needle tip attached to the distal end of the cannula,

wherein at least the cam tube is slidably mounted to translate within the interior lumen of the cannula.

3. The scissors end effector assembly of claim 2 , further comprising:

a standoff collar attached to the proximal end of the cam tube;

a rod hub with a rod attached to a distal end of the standoff collar;

a cam spring installed over the rod and disposed between the rod hub and the standoff collar; and

a lock hub defining an interior lumen, the lock hub including a lock collar flange for securing the scissors end effector assembly to a handle of a surgical instrument,

wherein a proximal end of the cam tube extends through the interior lumen of the lock hub to a connection point with the standoff collar.

4. The scissors end effector assembly of claim 2 , wherein the top shear defines a top cam lobe disposed on a proximal portion of the top shear, the top cam lobe extending toward an inner cutting surface of the top shear,

wherein the bottom shear defines a bottom cam lobe disposed on a proximal portion of the bottom shear, the bottom cam lobe extending toward an inner cutting surface of the bottom shear, and

wherein the cam bushing contacts the top cam lobe and the bottom cam lobe, and a force applied by the cam bushing in a distal direction biases the top shear and the bottom shear toward an open position via the top cam lobe and the bottom cam lobe, respectively.

5. The scissors end effector assembly of claim 4 , wherein the top shear defines a top open stop disposed on a proximal portion of the top shear, the top open stop extending away from the inner cutting surface of the top shear,

wherein the bottom shear defines a bottom open stop disposed on a proximal portion of the bottom shear, the bottom open stop extending away from the inner cutting surface of the bottom shear, and

wherein the top open stop and the bottom open stop contacts the cam bushing to limit a maximum opening angle of the top shear and the bottom shear.

6. The scissors end effector assembly of claim 4 , wherein the top shear defines a first closing cam profile surface on an outer edge of the top shear, opposite of the inner cutting surface of the top shear, and

wherein the bottom shear defines a second closing cam profile surface on an outer edge of the bottom shear, opposite of the inner cutting surface of the bottom shear.

7. The scissors end effector assembly of claim 6 , wherein the first closing cam profile surface and the second closing cam profile surface contact at least a portion of the needle tip, and

wherein the top shear and the bottom shear are guided toward a closed position, via the first closing cam profile surface and the second closing cam profile surface as the top shear and the bottom shear are retracted within the needle tip.

8. The scissors end effector assembly of claim 6 , wherein the first closing cam profile surface and the second closing cam profile surface are asymmetrical with respect to one another.

9. The scissors end effector assembly of claim 2 , wherein the cannula has an outer diameter of 3 mm or less.

10. The scissors end effector assembly of claim 2 , wherein the cannula is wrapped or coated with an insulating material.

11. The scissors end effector assembly of claim 1 , wherein each of the upper arm and the lower arm defines a mounting hole on a distal end thereof,

wherein each of the top shear and the bottom shear defines a mounting hole on a proximal end thereof, and

wherein the mounting holes of the upper arm and the lower arm, and the mounting holes of the top shear and the bottom shear are secured together via at least one fastener.

12. A needlescopic surgical device comprising:

the scissors end effector assembly of claim 1 ; and

a handle assembly having a trigger handle pivotally attached to the handle assembly, and having a hub for receiving an end effector assembly, wherein at least the cam tube of the scissors end effector assembly is inserted into the hub of the handle assembly.

13. The needlescopic surgical device of claim 12 , wherein the scissors end effector assembly further comprises:

a cannula defining an interior lumen, the cannula having a proximal end and a distal end; and

a needle tip attached to the distal end of the cannula,

wherein at least the cam tube is slidably mounted to translate within the interior lumen of the cannula.

14. The needlescopic surgical device of claim 13 , wherein the cannula has an outer diameter of 3 mm or less.

15. The needlescopic surgical device of claim 12 , wherein the scissors end effector assembly further comprises a lock hub with a lock collar flange attached, the lock hub defining an interior lumen for supporting a proximal end of the cam tube, and

wherein the hub of the handle assembly includes at least one at least one inwardly extending protrusion or latch to engage a slot defined by the lock collar flange.

16. The needlescopic surgical device of claim 12 , wherein the top shear defines a top cam lobe disposed on a proximal portion of the top shear, the top cam lobe extending toward an inner cutting surface of the top shear,

wherein the bottom shear defines a bottom cam lobe disposed on a proximal portion of the bottom shear, the bottom cam lobe extending toward an inner cutting surface of the bottom shear, and

wherein the cam bushing contacts the top cam lobe and the bottom cam lobe, and a force applied by the cam bushing in the distal direction biases the top shear and the bottom shear toward an open position via the top cam lobe and the bottom cam lobe, respectively.

17. The needlescopic surgical device of claim 16 , wherein the top shear defines a top open stop disposed on a proximal portion of the top shear, the top open stop extending away from the inner cutting surface of the top shear,

wherein the bottom shear defines a bottom open stop disposed on a proximal portion of the bottom shear, the bottom open stop extending away from the inner cutting surface of the bottom shear, and

wherein the top open stop and the bottom open stop contacts the cam bushing to limit a maximum opening angle of the top shear and the bottom shear.

18. The needlescopic surgical device of claim 16 , wherein the top shear defines a first closing cam profile surface on an outer edge of the top shear, opposite of the inner cutting surface of the top shear, and

wherein the bottom shear defines a second closing cam profile surface on an outer edge of the bottom shear, opposite of the inner cutting surface of the bottom shear.

19. The needlescopic surgical device of claim 18 , wherein the first closing cam profile surface and the second closing cam profile surface are asymmetrical with respect to one another.

20. A method of using the scissors end effector assembly of claim 1 further including a fastener and a needle tip, the method comprising:

inserting at least the cam tube of the scissors end effector assembly into a hub of a handle assembly;

actuating a trigger handle of the handle assembly to advance the needle tip over the top and bottom shears and to place the top and bottom shears in a closed position;

puncturing, with the needle tip, through a body wall and into a body cavity such that at least the top and bottom shears are within the body cavity;

retracting the needle tip to move the top and bottom shears towards an open position; and

cutting a target by at least partially advancing the needle tip over the top and bottom shears and moving the top and bottom shears from the open position toward the closed position.