Open vessel sealing instrument with cutting mechanism

1. An open electrosurgical forceps for sealing tissue, comprising:

a pair of first and second shaft members each having a jaw member disposed at a distal end thereof, the shaft members movable relative to each other to move the jaw members about a pivot from a first position in spaced relation relative to one another to at least one subsequent position wherein the jaw members cooperate to grasp tissue therebetween;

each of said jaw members including an electrically conductive sealing surface for communicating electrosurgical energy through tissue held therebetween;

at least one of the jaw members including a cutting slot defined along a length thereof, the cutting slot configured to accommodate reciprocation of a cutting instrument therethrough;

an actuator operably coupled to one of the first and second shaft members for selectively advancing the cutting instrument from a first position wherein the cutting instrument is disposed proximal to tissue held between the jaw members to at least one subsequent position wherein the cutting instrument is disposed distal to tissue held between the jaw members,

wherein upon movement of the jaw members to the at least one subsequent position to grasp tissue therebetween, the shaft members are further moveable toward each other to at least one of a plurality of positions corresponding to a specific closing force between the jaw members; and

a lockout formed on a part of at least one of the jaw members, the lockout configured to engage the cutting instrument to prevent advancement of the cutting instrument through tissue.

2. An open forceps according to claim 1 , wherein the lockout is formed on the pivot, the cutting instrument configured to engage the pivot when the jaw members are in the open position to prevent advancement of the cutting instrument through tissue.

3. An open forceps according to claim 2 , wherein the pivot includes a detent disposed thereon configured to engage a corresponding notch disposed in the cutting instrument when the jaw members are in the open position to prevent advancement of the cutting instrument through tissue.

4. An open forceps according to claim 2 , wherein the cutting instrument is configured to disengage the pivot when the jaw members are in the at least one subsequent position to permit advancement of the cutting instrument through tissue.

5. An open forceps according to claim 1 , wherein the cutting instrument is advanced from the first position to the at least one subsequent position at an angle relative to a longitudinal axis defined by at least one of the shaft members.

6. An open forceps according to claim 1 , wherein the plurality of positions are successive positions that increase a closure pressure between the electrically conductive sealing surfaces.

7. An open forceps according to claim 1 , wherein each shaft member includes a ratchet interface disposed thereon that cooperates with a corresponding ratchet interface of the opposing shaft member to interlock the shaft members at the at least one position upon movement of the shaft members toward each other.

8. An open forceps according to claim 7 , wherein the ratchet interfaces abut one another upon movement of the jaw members to the at least one subsequent position.

9. An open forceps according to claim 7 , wherein each ratchet includes a plurality of flanges projecting from inner facing surface thereof that cooperate to interlock the shaft members in the at least one position.

10. An open forceps according to claim 1 , wherein at least one of the shaft members includes a visual indicator corresponding to the specific closing force between the jaw members.

11. An open forceps according to claim 1 , wherein the at least one position of the shaft members corresponds to a specific strain energy in the shaft members that corresponds to the specific closing force between the jaw members.

12. An open forceps according to claim 1 , wherein at least one of the shaft members is resiliently deformable to enable movement of the shaft members toward each other to the at least one of the plurality of positions corresponding to a specific closing force between the jaw members.

13. An open forceps according to claim 1 , wherein a spring constant of at least one of the shaft members enables movement of the shaft members toward each other to the at least one of a plurality of positions corresponding to a specific closing force between the jaw members.

14. An open electrosurgical forceps for sealing tissue, comprising:

a pair of first and second shaft members each having a jaw member disposed at a distal end thereof, the shaft members movable relative to each other to move the jaw members about a pivot from a first position in spaced relation relative to one another to at least one subsequent position wherein the jaw members cooperate to grasp tissue therebetween;

each of said jaw members including an electrically conductive sealing surface for communicating electrosurgical energy through tissue held therebetween;

at least one of the jaw members including a cutting slot defined along a length thereof, the cutting slot configured to accommodate reciprocation of a cutting instrument therethrough;

an actuator operably coupled to one of the first and second shaft members for selectively advancing the cutting instrument from a first position wherein the cutting instrument is disposed proximal to tissue held between the jaw members to at least one subsequent position wherein the cutting instrument is disposed distal to tissue held between the jaw members,

wherein upon movement of the jaw members to the at least one subsequent position to grasp tissue therebetween, the shaft members are further moveable toward each other to at least one of a plurality of positions corresponding to a specific closing force between the jaw members; and

a lockout operably coupled to the cutting instrument and forming part of the pivot, wherein the cutting instrument operably engages the pivot when the jaw members are in the open position to prevent advancement of the cutting instrument through tissue.

15. An open forceps according to claim 14 , wherein the pivot includes a detent disposed thereon configured to engage a corresponding notch disposed in the cutting instrument when the jaw members are in the open position to prevent advancement of the cutting instrument through tissue.

16. An open forceps according to claim 14 , wherein the cutting instrument operably disengages the pivot when the jaw members are in the at least one subsequent position to permit advancement of the cutting instrument through tissue.

17. An open forceps according to claim 14 , wherein the cutting instrument is advanced from the first position to the at least one subsequent position at an angle relative to a longitudinal axis defined by at least one of the shaft members.

18. An open electrosurgical forceps for sealing tissue, comprising:

a pair of first and second shaft members each having a jaw member disposed at a distal end thereof, the shaft members movable relative to each other to move the jaw members about a pivot from a first position in spaced relation relative to one another to at least one subsequent position wherein the jaw members cooperate to grasp tissue therebetween, wherein upon movement of the jaw members to the at least one subsequent position to grasp tissue therebetween, the shaft members are further moveable toward each other to at least one of a plurality of positions corresponding to a specific closing force between the jaw members;

each of said jaw members including an electrically conductive sealing surface for communicating electrosurgical energy through tissue held therebetween;

at least one of the jaw members including a cutting slot defined along a length thereof, the cutting slot configured to accommodate reciprocation of a cutting instrument therethrough, the cutting instrument configured to engage at least a portion of the pivot to inhibit reciprocation of the cutting instrument through the cutting slot;

an actuator operably coupled to one of the first and second shaft members for selectively advancing the cutting instrument from a first position wherein the cutting instrument is disposed proximal to tissue held between the jaw members to at least one subsequent position wherein the cutting instrument is disposed distal to tissue held between the jaw members, wherein the cutting instrument is advanced from the first position to the at least one subsequent position at an angle relative to a longitudinal axis defined by at least one of the shaft members.