Knife deployment mechanisms for surgical forceps

1. A surgical instrument, comprising:

an end effector assembly having first and second jaw members, at least one of the jaw members movable relative to the other between a spaced-apart position, a first approximated position defining a first gap distance therebetween, and a second approximated position defining a second gap distance therebetween;

a knife selectively movable relative to the end effector assembly between a retracted position, a first extended position in which the knife extends between the jaw members a first distance, and a second extended position in which the knife extends between the jaw members a second distance;

a trigger selectively actuatable between a un-actuated position, a first actuated position, and a second actuated position for moving the knife between the retracted position, the first extended position, and the second extended position; and

at least one control member operably coupled to the trigger, the at least one control member configured to: prevent movement of the trigger from the un-actuated position when the jaw members are disposed in the spaced-apart position, permit movement of the trigger from the un-actuated position to the first actuated position and prevent movement of the trigger beyond the first actuated position when the jaw members are disposed in the first approximated position, and permit movement of the trigger from the un-actuated position to the second actuated position and prevent movement of the trigger beyond the second actuated position when the jaw members are disposed in the second approximated position.

2. The surgical instrument according to claim 1 , further comprising a drive assembly coupled to at least one of the jaw members, the drive assembly including a mandrel, the mandrel selectively translatable between a first position, a second position, and a third position for moving the jaw members between the spaced-apart position, the first approximated position, and the second approximated position, respectively.

3. The surgical instrument according to claim 2 , further comprising a movable handle coupled to the mandrel, the movable handle movable between an initial position, a first compressed position, and second compressed position for moving the jaw members between the spaced-apart position, the first approximated position, and the second approximated position, respectively.

4. The surgical instrument according to claim 2 , wherein a first control member is engaged to the mandrel and is movable therewith such that: in the first position, the first control member interferes with the trigger to prevent actuation of the trigger from the un-actuated position; in the second position, the first control member permits movement of the trigger from the un-actuated position to the first actuated position but interferes with the trigger to prevent actuation of the trigger beyond the first actuated position; and, in the third position, the first control member permits movement of the trigger from the un-actuated position to the second actuated position but interferes with the trigger to prevent actuation of the trigger beyond the second actuated position.

5. The surgical instrument according to claim 4 , further comprising a second control member coupled to the trigger, the second control member operable to engage the first control member to prevent actuation of the trigger from the un-actuated position when the jaw members are disposed in the spaced-apart position; prevent actuation of the trigger beyond the first actuated position when the jaw members are disposed in the first approximated position; and prevent actuation of the trigger beyond the second actuated position when the jaw members are disposed in the second approximated position.

6. The surgical instrument according to claim 2 , wherein the at least one control member includes an elongated body having a plurality of spaced-apart protrusions extending therefrom, the elongated body movable, upon movement of the mandrel between the first, second, and third positions, between a first blocking position, wherein a first protrusion prevents actuation of the trigger from the un-actuated position, a second blocking position, wherein a second protrusion prevents actuation of the trigger beyond the first actuated position, and a third blocking position, wherein a third protrusion prevents actuation of the trigger beyond the second actuated position.

7. The surgical instrument according to claim 1 , wherein at least one of the jaw members includes a knife channel defined therein, the knife channel configured to permit reciprocation of the knife therethrough.

8. The surgical instrument according to claim 7 , wherein, when the jaw members are disposed in the first approximated position, a relatively smaller portion of the knife is disposed within the at least one knife channel during extension of the knife between the jaw members, and wherein, when the jaw members are disposed in the second approximated position, a relatively greater portion of the knife is disposed within the at least one knife channel during extension of the knife between the jaw members.

9. A surgical instrument, comprising:

an end effector assembly having first and second jaw members, at least one of the jaw members movable relative to the other between a spaced-apart position, a first approximated position defining a first gap distance therebetween, and a second approximated position defining a second gap distance therebetween;

a knife selectively movable relative to the end effector assembly between a retracted position, a first extended position in which the knife extends between the jaw members a first distance, and a second extended position in which the knife extends between the jaw members a second distance;

a trigger selectively actuatable between a un-actuated position, a first actuated position, and a second actuated position for moving the knife between the retracted position, the first extended position, and the second extended position, respectively, the trigger having a resistance associated with moving the trigger; and

at least one control member operably coupled to the trigger, the at least one control member configured to: provide a first additional resistance to movement of the trigger upon movement of the trigger from the un-actuated position when the jaw members are disposed in the spaced-apart position, provide a second additional resistance to movement of the trigger upon movement of the trigger beyond the first actuated position when the jaw members are disposed in the first approximated position, and provide a third additional resistance to movement of the trigger upon movement of the trigger beyond the second actuated position when the jaw members are disposed in the second approximated position.

10. The surgical instrument according to claim 9 , wherein the first, second and third additional resistances provide tactile feedback to a user actuating the trigger.

11. The surgical instrument according to claim 9 , further comprising a drive assembly coupled to at least one of the jaw members, the drive assembly including a mandrel, the mandrel selectively translatable between a first position, a second position, and a third position for moving the jaw members between the spaced-apart position, the first approximated position, and the second approximated position, respectively.

12. The surgical instrument according to claim 11 , wherein a first control member is operably coupled to the mandrel and is movable therewith such that: in the first position, the first control member is positioned to provide the first additional resistance upon movement of the trigger from the un-actuated position; in the second position, the first control member is positioned to provide the second additional resistance upon movement of the trigger beyond the first actuated position; and, in the third position, the first control member is positioned to provide the third additional resistance upon movement of the trigger beyond the second actuated position.

13. The surgical instrument according to claim 12 , further comprising a second control member coupled to the trigger, the second control member operable to engage the first control member to provide the first additional resistance upon movement of the trigger from the un-actuated position; provide the second additional resistance upon movement of the trigger beyond the first actuated position; and provide the third additional resistance upon movement of the trigger beyond the second actuated position.

14. The surgical instrument according to claim 13 , wherein at least one of the first and second control members is configured to provide audible feedback upon engagement of the first and second control members.

15. The surgical instrument according to claim 11 , wherein the at least one control member includes an elongated body having a plurality of spaced-apart protrusions extending therefrom, the elongated body movable, upon movement of the mandrel between the first, second, and third positions, between a first blocking position, wherein a first protrusion provides the first additional resistance to the trigger, a second blocking position, wherein a second protrusion provides the second additional resistance to the trigger, and a third blocking position, wherein a third protrusion provides the third additional resistance to the trigger.

16. The surgical instrument according to claim 15 , wherein at least one of the first, second, and third protrusions is formed from a resiliently-flexible material.

17. The surgical instrument according to claim 9 , further comprising a movable handle operably coupled to at least one of the jaw members, the movable handle movable between an initial position, a first compressed position, and second compressed position for moving the jaw members between the spaced-apart position, the first approximated position, and the second approximated position, respectively.

18. The surgical instrument according to claim 9 , wherein at least one of the jaw members includes a knife channel defined therein, the knife channel configured to permit reciprocation of the knife therethrough.

19. The surgical instrument according to claim 18 , wherein, when the jaw members are disposed in the first approximated position, a relatively smaller portion of the knife is disposed within the at least one knife channel during extension of the knife between the jaw members, and wherein, when the jaw members are disposed in the second approximated position, a relatively greater portion of the knife is disposed within the at least one knife channel during extension of the knife between the jaw members.