Deployment mechanisms for surgical instruments

A surgical instrument includes a first actuation assembly coupled to a first component and movable from a first position to a second position to actuate the first component. A biasing member coupled to the first actuation assembly is configured to bias the first actuation assembly towards the first position. A second actuation assembly is coupled to a second component and is selectively actuatable to actuate the second component. The second actuation assembly is coupled to the first actuation assembly such that actuation of the second actuation assembly effects movement of the first actuating assembly from the first position towards the second position. A linkage assembly is configured to reduce the bias applied to the first actuation assembly when the second actuation assembly effects movement of the first actuation assembly.

BACKGROUND

Technical Field

The present disclosure relates to surgical instruments and, more particularly, to deployment mechanisms for deploying, e.g., actuating, one or more components of a surgical instrument.

Background of Related Art

Many surgical instruments include one or more movable handles, levers, actuators, triggers, etc. for actuating and/or manipulating one or more functional components of the surgical instrument. For example, a surgical forceps may include a movable handle that is selectively compressible relative to a stationary handle for moving first and second jaw members of the forceps between spaced-apart and approximated positions for grasping tissue therebetween. Such a forceps may further include a trigger for selectively deploying a knife between the jaw members to cut tissue grasped therebetween.

As can be appreciated, as additional functional components are added to the surgical instrument, additional deployment structures or deployment structures capable of actuating more than one component are required. However, multiple deployment structures and/or combined deployment structures may be limited by spatial constraints within the housing of the surgical instrument and/or functional constraints of the components, e.g., where a combined deployment structure imparts additional force requirements for deploying one or more of the components coupled thereto.

SUMMARY

As used herein, the term “distal” refers to the portion that is being described that is further from a user, while the term “proximal” refers to the portion that is being described that is closer to a user. Further, to the extent consistent, any of the aspects described herein may be used in conjunction with any of the other aspects described herein.

In accordance with the present disclosure, a surgical instrument is provided including an end effector assembly, a knife, a trigger assembly, a biasing member, a monopolar assembly, a lever assembly, and a linkage. The end effector assembly includes first and second jaw members. One or both of the jaw members is movable relative to the other between a spaced-apart position and an approximated position for grasping tissue therebetween. The knife is selectively movable relative to the jaw members between a retracted position and an extended position, wherein the knife extends between the jaw members to cut tissue grasped therebetween. The trigger assembly is coupled to the knife and is selectively movable from an un-actuated position to an actuated position to move the knife from the retracted position to the extended position. The biasing member is coupled to the trigger assembly and is configured to apply a biasing force to the trigger assembly to bias the trigger assembly towards the un-actuated position. The monopolar assembly includes an energizable member and is selectively movable relative to the jaw members between a stored position and a use position, wherein the energizable member extends distally from the jaw members. The lever assembly is coupled to the monopolar assembly and is selectively movable from a first position to a second position to move the monopolar assembly from the stored position to the use position. The lever assembly is also coupled to the trigger assembly such that movement of the lever assembly from the first position to the second position effects movement of the trigger assembly from the un-actuated position towards the actuated position. The linkage assembly is coupled to the lever assembly and the biasing member and is configured to reduce the biasing force applied to the trigger assembly when the lever assembly effects movement of the trigger assembly from the un-actuated position towards the actuated position.

In one aspect, the monopolar assembly further includes an insulative sleeve. Upon movement of the monopolar assembly from the stored position to the use position, the insulative sleeve is moved from a proximal position to a distal position, wherein the insulative sleeve is disposed about the jaw members.

In another aspect, the lever assembly is configured to contact the trigger assembly upon actuation of the lever assembly to urge the trigger assembly from the un-actuated position towards the actuated position.

In yet another aspect, the trigger assembly and lever assembly are partially (or entirely) disposed within a housing configured to guide movement of the trigger assembly and/or lever assembly.

A surgical instrument provided in accordance with the present disclosure includes a first actuation assembly, a biasing member, a second actuation assembly, and a linkage assembly. The first actuation assembly is coupled to a first component and is selectively movable from a first position to a second position to actuate the first component. The biasing member is coupled to the first actuation assembly and is configured to apply a biasing force to the first actuation assembly to bias the first actuation assembly towards the first position. The second actuation assembly is coupled to a second component and is selectively actuatable to actuate the second component. The second actuation assembly is also coupled to the first actuation assembly such that actuation of the second actuation assembly effects movement of the first actuating assembly from the first position towards the second position. The linkage assembly is coupled to the second actuation assembly and the biasing member. The linkage assembly is configured to reduce the biasing force applied to the first actuation assembly when the second actuation assembly effects movement of the first actuation assembly from the first position towards the second position.

In one aspect, a portion of the second actuation assembly is configured to contact a portion of the first actuation assembly upon actuation of the second actuation assembly to urge the first actuation assembly from the first position towards the second position.

In another aspect, the first actuation assembly includes a trigger pivotable from an un-actuated position to an actuated position for moving the first actuation assembly from the first position to the second position.

In another aspect, the second actuation assembly includes a lever pivotable from a proximal position to a distal position for actuating the second actuation assembly.

In yet another aspect, the first and second actuation assemblies are at least partially disposed within a housing.

In still yet another aspect, the housing defines at least one track configured to guide movement of at least one of the first actuation assembly between the first and second positions and actuation of the second actuation assembly.

In another aspect, the biasing member is coupled to the first actuation assembly at a first end thereof and to the linkage assembly at a second end thereof.

In yet another aspect, the first actuation assembly is configured to move the first end of the biasing member distally upon movement of the first actuation assembly from the first position towards the second position.

In still another aspect, the linkage is configured to maintain the second end of the biasing member in substantially fixed position when the second actuation assembly is un-actuated.

In still yet another aspect, the linkage is configured to move the second end of the biasing member distally upon actuation of the second actuation assembly.

In another aspect, the linkage is configured to move the second end of the biasing member distally a distance that is substantially equal to a distance the first actuation assembly is configured to move the first end of the biasing member distally upon movement of the first actuation assembly from the first position towards the second position.

A method of actuating components of a surgical instrument is also provided in accordance with the present disclosure. The method includes moving a first actuation assembly against a biasing force from a first position to a second position to actuate a first component, returning the first actuation assembly from the second position back to the first position, and moving a second actuation assembly to actuate a second component. Moving the second actuation assembly effects movement of the first actuation assembly from the first position to the second position under a reduced biasing force.

In one aspect, a trigger is moved from an un-actuated position to an actuated position to move the first actuation assembly from the first position to the second position.

In another aspect, a lever is moved from a proximal position to a distal position to move the second actuation assembly.

In another aspect, a biasing member applies the biasing force to bias the first actuation assembly towards the first position.

In still another aspect, the first actuation assembly is returned from the second position to the first position under the biasing force.

DETAILED DESCRIPTION

Referring now toFIGS. 1-7, a forceps provided in accordance with the present disclosure is shown generally identified by reference numeral10. Forceps10, as will be described below, is configured to operate in both a bipolar mode, e.g., for grasping, treating, and/or dissecting tissue, and a monopolar mode, e.g., for treating and/or dissecting tissue. Although the present disclosure is shown and described with respect to forceps10, the aspects and features of the present disclosure are equally applicable for use with any suitable surgical instrument or portion(s) thereof for actuating, moving, and/or deploying the assemblies and/or components of the surgical instrument. Obviously, different connections and considerations apply to each particular instrument and the assemblies and/or components thereof; however, the aspects and features of the present disclosure remain generally consistent regardless of the particular instrument, assemblies, and/or components provided.

Continuing with reference toFIGS. 1-7, forceps10defines a longitudinal axis “X-X” and includes a housing20, a handle assembly30, a trigger assembly60, a rotating assembly70, a lever assembly80, an end effector assembly100, and a monopolar assembly200. Forceps10further includes a shaft12having a distal end14configured to mechanically engage end effector assembly100and a proximal end16that mechanically engages housing20. Forceps10also includes electrosurgical cable2that connects forceps10to a generator (not shown) or other suitable power source, although forceps10may alternatively be configured as a battery powered instrument. Cable2includes wires2aextending therethrough that have sufficient length to extend through shaft12in order to provide electrical energy to at least one of the electrically-conductive plates112,122of jaw members110,120, respectively, of end effector assembly100, e.g., upon activation of activation switch4in a bipolar mode. Wires2bof cable2, on the other hand, extend through housing20in order to provide electrical energy to monopolar assembly200, e.g., upon activation of activation switch4in a monopolar mode. Rotating assembly70is rotatable in either direction about longitudinal axis “X-X” to rotate end effector100and monopolar assembly200about longitudinal axis “X-X.” Housing20houses the internal working components of forceps10, which will be described in detail, in turn, below.

Referring toFIGS. 1-3, end effector assembly100is shown attached at a distal end14of shaft12and includes a pair of opposing jaw members110,120pivotably coupled to one another about a pivot102. Each of the jaw members110and120includes an electrically-insulative outer jaw housing111,121an electrically-conductive plate112,122disposed atop respective jaw housings111,121, and a proximally-extending flange114,124, respectively. Pivot102extends through flanges114,124to pivotably couple jaw members110,120to one another. One or both of plates112,122are adapted to connect to a source of energy (not explicitly shown), e.g., via wires2a(FIG. 4), for conducting energy therebetween and through tissue grasped between jaw members110,120to treat, e.g., seal, tissue. More specifically, in some embodiments, end effector assembly100defines a bipolar configuration wherein plate112is charged to a first electrical potential and plate122is charged to a second, different electrical potential such that an electrical potential gradient is created for conducting energy between plates112,122and through tissue grasped therebetween for treating e.g., sealing, tissue. Activation switch4(FIG. 1) is coupled to wires2a(FIG. 4), thus allowing the user to selectively apply energy to plates112,122of end effector assembly100during a bipolar mode of operation.

End effector assembly100is designed as a unilateral assembly, i.e., where jaw member120is fixed relative to shaft12and jaw member110is movable relative to shaft12and fixed jaw member120. However, end effector assembly100may alternatively be configured as a bilateral assembly, i.e., where both jaw member110and jaw member120are movable relative to one another and to shaft12. In one some embodiments, a knife channel115,125(FIGS. 8A-8D) may be defined within one or both of jaw members110,120to permit reciprocation of knife184therethrough, e.g., upon actuation of trigger62of trigger assembly60.

With reference toFIGS. 1, 4, and 5, handle assembly30includes a movable handle40and a fixed handle50. Fixed handle50is integrally associated with housing20and movable handle40is movable relative to fixed handle50. Movable handle40is pivotably coupled to housing20via pivot41and is pivotable about pivot41and relative to fixed handle50between an initial position, wherein movable handle40is spaced from fixed handle50, and a compressed position, wherein movable handle40is compressed towards fixed handle50. A biasing member (not shown) may be provided to bias movable handle40towards the initial position. Movable handle40is ultimately connected to a drive assembly150that, together, mechanically cooperate to impart movement of jaw members110,120between a spaced-apart position (FIG. 8A) and an approximated position (FIG. 8B) to grasp tissue between electrically-conductive plates112,122of jaw members110,120, respectively. Drive assembly150will be described in greater detail below.

Continuing with reference toFIGS. 1, 4, and 5, as mentioned above, drive assembly150interconnects movable handle40and end effector assembly100. Movable handle40includes a handle portion43defining a finger hole44and a bifurcated arm45extending upwardly from handle portion43and into housing20. Arm45is bifurcated to define first and second spaced-apart flanges46that are pivotably coupled to housing20at the free ends thereof via pivot41. Flanges46extend on either side of drive assembly150and are coupled thereto to facilitate movement of jaw members110,120between the spaced-apart position and approximated positions. More specifically, flanges46extend upwardly on either side of mandrel152and are disposed within lateral slots154defined within mandrel152such that pivoting of movable handle40about pivot41between the initial and compressed positions effects corresponding longitudinal translation of mandrel152.

Mandrel152is fixedly engaged about the proximal end of an elongated drive member156. Elongated drive member156extends distally from housing20and through shaft12, ultimately coupling to end effector assembly100. More specifically, elongated drive member156includes a transverse drive pin158disposed towards a distal end thereof that is pivotably disposed within aperture116defined within proximal flange114of movable jaw member110, such that proximal translation of elongated drive member156pulls jaw member110to pivot relative to jaw member120towards the approximated position, while distal translation of elongated drive member156pushes jaw member110to pivot relative to jaw member120towards the spaced-apart position. As such, pivoting of movable handle40between the initial and compressed positions effects movement of drive member156(between a first, un-actuated position and a second, actuated position), to pivot jaw members110,120between the spaced-apart and approximated positions.

Trigger assembly60, as shown inFIGS. 1 and 4-6, is coupled to knife assembly180such that trigger62is selectively actuatable from a first, un-actuated, distal position to a second, actuated, proximal position to advance knife184from a retracted position (FIG. 8B), wherein knife184is disposed proximally of jaw members110,120, to an extended position, wherein knife184extends between jaw members110,120and through knife channels115,125, respectively (FIG. 8C), to cut tissue grasped between jaw members110,120. Trigger assembly60will be described in greater detail below. Knife assembly180includes a knife drive rod182defining proximal and distal ends183a,183b, respectively. Proximal end183aof knife drive rod182is coupled to connector68of trigger assembly60by a base member188that defines a pair of opposed, lateral protrusions189. Knife drive rod182extends distally through elongated drive member156, which extends through mandrel152and shaft12, ultimately engaging the proximal end of knife184. Knife184defines a distal cutting edge186configured to facilitate the cutting of tissue upon translation of knife184therethrough.

Trigger assembly60includes a trigger62having a toggle member63and a bifurcated arm66extending upwardly from toggle member63and into housing20. Trigger62is pivotably coupled to housing20via pivot65, which extends through an intermediate portion64of trigger62. Arm66is bifurcated to define first and second spaced-apart flanges67to permit passage of arm66about drive assembly150. A pin69pivotably couples flanges67of trigger62to connector68. Connector68extends proximally through housing20, ultimately coupling to the proximal end of knife drive rod182of knife assembly180. Accordingly, upon pivoting of trigger62about pivot pin65and relative to housing20from the un-actuated position towards the actuated position, flanges67are rotated to pull connector68distally such that knife drive rod182is pushed distally (from a first, un-actuated position to a second, actuated position) to translate knife184from the retracted position towards the extended position. On the other hand, upon return of trigger62towards the un-actuated position, flanges67are rotated to push connector68proximally such that knife drive rod182is pulled proximally (from the second, actuated position back to the first, un-actuated position) to translate knife184back towards the retracted position. A biasing member140, e.g., a coil spring, is coupled to pin69at a distal end142thereof and to a linkage assembly300, which will be described in greater detail below, at a proximal end144thereof for biasing trigger62towards the un-actuated position, thereby biasing knife184towards the retracted position. Further, with additional reference toFIG. 7, housing20may define a pair of longitudinal tracks21on opposing sides thereof (only one is shown) that are configured to receive opposed, lateral protrusions189of base member188of knife drive rod182to guide translation of knife drive rod182and, thus, knife184between the retracted and extended positions.

Referring toFIGS. 1 and 4-6, lever assembly80is shown. Although lever assembly80is shown disposed on only one side of housing20, lever assembly80may be configured to define a symmetrical configuration having substantially similar components disposed on either side of housing20, thus allowing actuation of lever assembly80from either side of housing20. However, for purposes of simplicity, only one side of lever assembly80will be described herein.

Lever assembly80is disposed within a recess24defined on an exterior side surface of housing20(although lever assembly80may also be positioned at any other suitable location) and includes a lever82that is rotatable about a pivot84between a proximal position, wherein free end86of lever82is disposed at a proximal end25of recess24, and a distal position, wherein free end86of lever82is disposed at a distal end26of recess24. In configurations where lever assembly80defines a symmetrical configuration, a pair of levers82are provided on either side of housing20, each of which is coupled to one end of pivot84. Pivot84is rotatably coupled to housing20and extends through housing20. A pair of arms90disposed within housing20on opposed sides thereof are coupled to pivot84and extend therefrom. More specifically, each arm90is engaged about pivot84of lever assembly80at the first end92thereof such that rotation of pivot84relative to housing20, e.g., via rotation of lever82, effects rotation of second ends94of arms90about first ends92thereof. Each arm90further includes a slot96defined therethrough towards second end94thereof. Slots96are configured to slidably receive transverse pin204of hub203of drive shaft202of monopolar assembly200therein such that, upon rotation of arms90about pivot84, e.g., upon actuation of lever82, the angular displacement of arms90is converted into longitudinal translation of hub203and, thus, longitudinal translation of drive shaft202of monopolar assembly200(from a first, un-actuated position, to a second, actuated position) to move insulative sleeve210and energizable rod member220of monopolar assembly200from the retracted position (FIGS. 2 and 8C) to the deployed position (FIGS. 3 and 8D), as will be described in greater detail below.

With reference toFIGS. 1-7, monopolar assembly200includes a drive shaft202, a ferrule208, an insulative sleeve210, and an energizable rod member220. Drive shaft202includes a hub203disposed at the proximal end thereof. Hub203includes a having a transverse pin204extending outwardly therefrom. Transverse pin204, as mentioned above, is configured for slidable receipt within slots96of arms90of lever assembly80such that pivotal movement of lever82effects longitudinal translation of transverse pin204and, thus, drive shaft202. Opposed ends of transverse pin204are configured for slidable receipt within longitudinal tracks21of housing20(seeFIG. 7) to guide longitudinal translation of drive shaft202and, thus, monopolar assembly200between the retracted position (FIGS. 2 and 8C) and the deployed position (FIGS. 3 and 8D).

Drive shaft202is slidably disposed within knife drive rod182and elongated drive member156and is coupled to ferrule208towards the distal end thereof. More specifically, knife drive rod182and elongated drive member156each define a longitudinal slot187,159, respectively, therethrough, that allows engagement of ferrule208, which is disposed about shaft12, to drive shaft202of monopolar assembly200via one or more pins209, although other suitable engagements may also be provided. Ferrule208engages insulative sleeve210and energizable rod member220to drive shaft202such that longitudinal translation of drive shaft202effects corresponding longitudinal translation of insulative sleeve210and energizable rod member220. Accordingly, actuation of lever82may be effected to translate drive shaft202distally, thereby moving insulative sleeve210and energizable rod member220from the retracted position (FIGS. 2 and 8C) to the deployed position (FIGS. 3 and 8D).

Insulative sleeve210is slidably disposed about shaft12and is configured for translation about and relative to shaft12between a retracted position (FIGS. 2 and 8C), where insulative sleeve210is disposed proximally of end effector assembly100, and a deployed position (FIGS. 3 and 8D), wherein insulative sleeve210is substantially disposed about end effector100so as to electrically insulate plates112,122of jaw members110,120, respectively, from the surroundings of insulative sleeve210. Energizable rod member220extends through sleeve210and distally therefrom, ultimately defining an electrically-conductive distal tip224. Distal tip224may be hook-shaped (as shown), or may define any other suitable configuration, e.g., linear, circular, angled, etc. Energizable rod member220and, more specifically, distal tip224thereof, functions as the active electrode of monopolar assembly200. Sleeve210and rod member220may be fixedly engaged to one another and/or ferrule208such that sleeve210and rod member220move in concert with one another between their retracted position (FIGS. 2 and 8C) and the deployed position (FIG. 8D), e.g., upon actuation of lever82(FIG. 1), although other configurations may also be provided. Wires2b, which extend from electrosurgical cable2through housing20, are coupled to energizable rod member220to provide energy to energizable rod member220, e.g., upon actuation of activation switch4(FIG. 1) in a monopolar mode, for treating tissue in a monopolar mode of operation.

In the retracted position, as shown inFIGS. 2 and 8C, distal tip224of monopolar assembly200is disposed within an insulating member126, e.g., an insulated recess defined within proximal flange124of jaw member120, although other configurations are also contemplated. Insulating member126is electrically-insulated such that distal tip224of rod member220is isolated from electrically-conductive plates112,122of jaw members110,120, respectively, and from surrounding tissue when disposed in the retracted position. Alternatively, distal tip224of rod member220may only be insulated from plate112. In such configurations, distal tip224of rod member220is capable of being energized to the same polarity as plate122. In the extended position, as shown inFIGS. 3 and 8D, distal tip224of rod member220extends distally from end effector assembly100and insulative sleeve210, which substantially surrounds end effector assembly100. In this position, energy may be applied to distal tip224of rod member220to treat tissue, e.g., via activation of activation switch4(FIG. 1) in the monopolar mode.

With reference toFIGS. 4 and 6, in conjunction withFIGS. 1-3, 5, and 7, a portion of distal surfaces99of arms90abut the proximal end of connector68of trigger assembly60when trigger62is disposed in the un-actuated position, e.g., when knife184is disposed in the retracted position. As such, upon actuation of lever82to rotate arms90about pivot84in the distal direction to thereby translate monopolar assembly200to the deployed position, distal surfaces99of arms90urge connector68distally. Distal urging of connector68, as mentioned above, translates knife184from the retracted position towards the extended position. This configuration, wherein arms90abut connector68such that knife184is translated to the extended position upon movement of monopolar assembly200to the deployed position is advantageous in that it allows these components to assume a more compact configuration, freeing up space within housing20for other components and/or allowing for a more compact housing20to be used. However, urging connector68distally to translate knife184from the retracted position towards the extended position upon deployment of monopolar assembly200requires that lever82be actuated with sufficient force so as to overcome the biasing force of biasing member140, which, as described above, biases trigger assembly60and, thus, connector68proximally.

In order to reduce the force required to actuate lever82while still providing the space-conserving benefits described above, a linkage assembly300is operably coupled between biasing member140of trigger assembly60and arms90of lever assembly80. However, the presently disclosed linkage assembly300is not limited to this particular use, as linkage assembly300may alternatively be used with any suitable components and/or assemblies of a surgical instrument.

Linkage assembly300includes a pair of spaced-apart linkage members310, each of which defines a first end312and a second end314. A first pin316extends between and outwardly from linkage members310at the first ends312thereof. Proximal end144of biasing member140is coupled to the portion of first pin316that extends between linkage members310, while the outwardly-extending portions of first pin316are configured for slidable receipt within linkage tracks27defined within housing20, as will be described in greater detail below. A second pin318extends between linkage members310at the second ends314thereof for pivotably coupling linkage members310to arms90of lever assembly80. As such, and as will be described in greater detail below, although the distal advancement of connector68, which is effected by actuation of lever82to translate monopolar assembly200to the deployed position, pulls distal end142of biasing member140distally, actuation of lever82also moves linkage members310and, thus, proximal end144of biasing member140distally, such that the tension on biasing member140is reduced (or removed) and a reduced biasing force (or no biasing force) from biasing member140is imparted to lever82, despite the fact that knife assembly180is being advanced towards the extended position.

With reference toFIG. 7, in conjunction withFIGS. 4-6, as mentioned above, housing20includes a pair of longitudinal tracks21(only one is shown) defined on either side thereof, and a pair of linkage tracks27(only one is shown) defined on either side thereof. Each longitudinal track21, as mentioned above, is configured to guide translation of lateral protrusions189of base member188of connector68and transverse pin204of hub203of drive shaft202therealong so as to guide translation of knife assembly180and monopolar assembly200, respectively, along substantially longitudinal paths. The proximal and distal ends of longitudinal tracks21may also be configured to define the retracted and extended positions of knife184and/or the retracted and deployed positions of monopolar assembly200, since translation of lateral protrusions189and transverse pin204through longitudinal tracks21is limited at least by the length of longitudinal tracks21, e.g., the proximal and distal ends thereof.

Each linkage track27defined within housing20is configured to guide translation of first pin316of linkage members310through housing20and to provide a safety lockout feature that inhibits accidental actuation of monopolar assembly200. More specifically, linkage tracks27each include a first, generally longitudinal portion28and a second portion29that angles downwardly and distally from the proximal end of first portion28. Thus, as will be described in greater detail below, with first pin316disposed at the bases of second portions29of linkage tracks27and biased distally via biasing member140, linkage members310are maintained in position and, thus, monopolar assembly200is locked in the retracted position. In this position, proximal end144of biasing member140is substantially fixed in position such that biasing member140may function to bias trigger assembly60towards the un-actuated position, thereby biasing knife184towards the retracted position. Once removed from second portions29of linkage tracks27, first pin316is permitted to translate along first portions28of linkage tracks27such that the tension on biasing member140remains substantially unchanged during actuation of monopolar assembly200, thereby substantially removing the biasing force of biasing member140from application during actuation of lever assembly80.

Turning now toFIGS. 8A-8D, in conjunction withFIGS. 1-7, the use and operation of forceps10in both the bipolar mode, e.g., for grasping, treating and/or cutting tissue, and the monopolar mode, e.g., for electrical/electromechanical tissue treatment, is described. Initially, with respect to the bipolar mode, as shown inFIG. 8A, jaw members110,120are disposed in the spaced-apart position. In the bipolar mode, monopolar assembly200remains disposed in the retracted position, as shown inFIGS. 8A-8C, wherein insulative sleeve210is positioned proximally of jaw members110,120and energizable rod member220is disposed in the retracted position within insulative member126of jaw member120. At this point, trigger assembly60is disposed in the un-actuated position such that knife184is disposed in the retracted position, lever82of lever assembly80is disposed at the proximal end25of recess24such that monopolar assembly200is disposed in the retracted position, and first pin316is disposed within second portions29of linkage tracks27.

With jaw members110,120disposed in the spaced-apart position, end effector assembly100may be maneuvered into position such that tissue to be grasped, treated, e.g., sealed, and/or cut, is disposed between jaw members110,120. Next, movable handle40is depressed, or pulled proximally relative to fixed handle50such that jaw member110is pivoted relative to jaw member120from the spaced-apart position to the approximated position to grasp tissue therebetween, as shown inFIG. 8B. In this approximated position, energy may be supplied, e.g., via activation of switch4, to plate112of jaw member110and/or plate122of jaw member120and conducted through tissue to treat tissue, e.g., to effect a tissue seal or otherwise treat tissue in the bipolar mode of operation.

Once tissue treatment is complete (or to cut untreated tissue), knife184of knife assembly180may be deployed from within shaft12to between jaw members110,120, e.g., via actuation of trigger62of trigger assembly60, to cut tissue grasped therebetween. More specifically, upon actuation of trigger62, knife184is advanced distally from shaft12to extend at least partially through knife channels115,125of jaw members110,120, respectively, to cut tissue grasped between jaw members110,120(FIG. 8C). Upon actuation of trigger62, protrusions189of knife drive bar182are translated along longitudinal tracks21of housing20to guide translation of knife184to the extended position. Further, at this point, first pin316remains disposed within second portions29of linkage tracks27. As such, proximal end144of biasing member140remains fixed in position while distal end142of biasing member140is advanced distally upon actuation of trigger62. During actuation of trigger62, first pin316is biased further towards the base of second portions29of linkage tracks27via biasing member140, thus locking monopolar assembly200in position and inhibiting accidental deployment of monopolar assembly.

When tissue cutting is complete, trigger62may be released to allow connector68and knife drive rod182to return proximally under the bias of biasing member142such that knife184is returned to the retracted position within shaft12. Next, jaw members110,120may be moved back to the spaced-apart position (FIG. 8A) to release the treated and/or divided tissue.

For operation of forceps10in the monopolar mode, movable handle40is first depressed relative to fixed handle50to pivot jaw member110relative to jaw member120from the spaced-apart position to the approximated position. With jaw members110,120disposed in the approximated position, monopolar assembly200may be translated from the retracted position (FIG. 8C) to the deployed position (FIG. 8D) via actuation of lever assembly80. More specifically, in order to translate insulative sleeve210and energizable rod member220of monopolar assembly200from the retracted position (FIG. 8C) to the deployed position (FIG. 8D), lever82is rotated through recess24of housing20from the proximal end25thereof to the distal end26thereof. Rotation of lever82in this manner rotates arms90similarly to urge pin204of hub203of drive shaft202distally such that insulative sleeve210is translated distally to the deployed position, wherein insulative sleeve210surrounds jaw members110,120(FIG. 8D) and energizable rod member220is likewise translated distally to the deployed position, wherein energizable rod member220extends distally from end effector assembly100(FIG. 8D).

At the same time as monopolar assembly200is advanced distally, arms90urge connector68distally such that pin69is advanced distally and such that knife184is translated from the extended position towards the retracted position. However, rotation of arms90also effects distal advancement of linkage members310, as first pin316is moved along linkage slots27from the second portion29thereof to the first portion28thereof. Once first pin316reaches first portion28of linkage slots27and is thus permitted to translate distally therealong, linkage members310are permitted to move distally to urge proximal end144of biasing member140distally a substantially equal distance as the distal translation of distal end142of biasing member140, which is engaged to pin69. As such, with a reduced (or removed) tension on biasing member140, a reduced biasing force (or no biasing force) from biasing member140is felt upon actuation of lever82.

Once monopolar assembly200is disposed in the deployed position, activation switch4may be actuated to supply energy to energizable rod member220to treat, e.g., dissect, tissue. During application of energy to tissue via energizable rod member220, forceps10may be moved relative to tissue, e.g., longitudinally along longitudinal axis “X-X” and/or radially therefrom, to facilitate electromechanical treatment of tissue. At the completion of tissue treatment, e.g., dissection, monopolar assembly200may be returned to the retracted position (FIG. 8C) via rotating lever82from the distal end26of recess24back to the proximal end25thereof. Rotation of lever82from the second position back to the first position rotates arms90back to their initial position such that linkage members310, trigger assembly60, and knife assembly180are likewise returned to their respective initial positions.