Vessel sealer and divider for large tissue structures

1. A bipolar forceps, comprising:

a housing;

a shaft affixed to the housing having jaw members at a distal end thereof, the shaft having a longitudinal axis defined therethrough, the jaw members adapted to connect to a source of electrosurgical energy such that the jaw members are capable of conducting energy through tissue held therebetween to effect a tissue seal;

a drive assembly that moves the jaw members relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members are closer to one another for manipulating tissue;

a movable handle rotatable about a pivot to force a drive flange of the drive assembly to move the jaw members between the first and second positions, the pivot located a fixed distance above the longitudinal axis and the drive flange located generally along the longitudinal axis; and

a knife assembly having a movable knife rod that operatively engages a knife blade, the knife rod having a first longitudinal section having a first predetermined shape and a second longitudinal section having a second predetermined shape, wherein the first and second longitudinal sections are separated by a third longitudinal section having a circular cross-section and the first predetermined shape is different than the second predetermined shape such that at least a onion of a profile of the knife rod increases from a proximal end thereof toward a distal end thereof.

2. A bipolar forceps according to claim 1 , wherein the first longitudinal section of the knife rod has a profile selected from the group consisting of a solid profile and a hollow profile.

3. A bipolar forceps according to claim 1 , wherein the first predetermined shape of the knife rod includes a uniform cross-section along the length of the first longitudinal section that is at least one of a circle, square, rectangle, triangle, quadrilateral, and polygon.

4. A bipolar forceps according to claim 3 , wherein the polygon cross-section includes at least one of a pentagon, hexagon, heptagon, octagon, nonagon, or decagon.

5. A bipolar forceps according to claim 1 , wherein the first longitudinal section of the knife rod has at least one longitudinal flange along the length thereof.

6. A bipolar forceps according to claim 1 , wherein the first longitudinal section of the knife rod has a width of about 0.20 inches to about 0.07 inches.

7. A bipolar forceps according to claim 1 , wherein the second longitudinal section of the knife rod has a thickness of about 0.15 inches to about 0.5 inches.

8. A bipolar forceps according to claim 1 , wherein the second longitudinal section of the knife rod includes at least one face shaped as a rack.

9. A bipolar forceps according to claim 1 wherein the first longitudinal section of the knife rod has a length of about 2 inches to about 5 inches along a longitudinal axis thereof and the second longitudinal section of the knife rod has a length of about 1 inches to about 2 inches along a longitudinal axis thereof.

10. A bipolar forceps according to claim 1 , wherein the third longitudinal section of the knife rod has a thickness of about 0.05 inches to about 0.20 inches.

11. A bipolar forceps according to claim 1 , further comprising a tapered edge between the first longitudinal section of the knife rod and the third longitudinal section of the knife rod.

12. A bipolar forceps according to claim 1 , wherein the knife blade includes a proximal end, a distal end, and a knife rod attachment section.

13. A bipolar forceps according to claim 12 , wherein the knife rod attachment section includes an aperture defined therein.

14. A bipolar forceps according to claim 12 , wherein the distal end of the knife blade includes a beveled edge having an angle of about 10° to about 30° relative to the vertical axis defined through the distal end.

15. A bipolar forceps according to claim 1 , wherein the knife rod is operatively coupled to a knife slidingly disposed within the shaft and wherein the forceps further comprises a finger actuator operatively coupled to the knife rod, wherein movement of the finger actuator moves the knife rod which, in turn, moves the knife to cut tissue disposed between the jaw members.

16. A bipolar forceps according to claim 15 , wherein the finger actuator is in the shape of a wheel on a proximal portion of the housing.

17. A bipolar forceps according to claim 15 , wherein the finger actuator is in the shape of a lever on a proximal portion of the housing.

18. A bipolar forceps according to claim 15 , wherein the finger actuator includes a wheel having a first rack, a pinion that rotates about a pivot to abut and force the second longitudinal section distally which, in turn, results in distal translation of the knife.

19. A bipolar forceps according to claim 1 , wherein the knife is selectively reciprocateable within a knife channel defined within at least one jaw member and wherein the forceps further comprises a knife guide configured to prevent tissue from entering the knife channel during activation.

20. A bipolar forceps according to claim 19 , wherein the knife guide includes a solid body that insulates the jaw members from one another.