Patent Publication Number: US-11660108-B2

Title: Trigger lockout and kickback mechanism for surgical instruments

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/814,602, filed on Jul. 31, 2015, which is a continuation of U.S. patent application Ser. No. 13/401,964, filed Feb. 22, 2012, now U.S. Pat. No. 9,113,940, which is a continuation-in-part of U.S. patent application Ser. No. 13/006,538, filed Jan. 14, 2011, now U.S. Pat. No. 8,945,175, the entire contents of each of which is incorporated by reference herein. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure relates to surgical instruments. More particularly, the present disclosure relates to a trigger lockout and kickback mechanism for use with surgical instruments. 
     Background of Related Art 
     Electrosurgical instruments, e.g., forceps, utilize both mechanical clamping action and electrical energy to effect hemostasis by heating tissue and blood vessels to coagulate, cauterize and/or seal tissue. As an alternative to open forceps for use with open surgical procedures, many modern surgeons use endoscopic or laparoscopic instruments for remotely accessing organs through smaller, puncture-like incisions or natural orifices. As a direct result thereof, patients tend to benefit from less scarring and reduced healing time. 
     Many endoscopic surgical procedures require cutting or ligating blood vessels or vascular tissue. Due to the inherent spatial considerations of the surgical cavity, surgeons often have difficulty suturing vessels or performing other traditional methods of controlling bleeding, e.g., clamping and/or tying-off transected blood vessels. By utilizing an endoscopic electrosurgical forceps, a surgeon can either cauterize, coagulate/desiccate and/or simply reduce or slow bleeding simply by controlling the intensity, frequency and duration of the electrosurgical energy applied through the jaw members to the tissue. Most small blood vessels, i.e., in the range below two millimeters in diameter, can often be closed using standard electrosurgical instruments and techniques. However, if a larger vessel is ligated, it may be necessary for the surgeon to convert the endoscopic procedure into an open-surgical procedure and thereby abandon the benefits of endoscopic surgery. Alternatively, the surgeon can seal the larger vessel or tissue. Typically, after a vessel or tissue is sealed, the surgeon advances a knife to sever the sealed tissue disposed between the opposing jaw members. 
     SUMMARY 
     As used herein, the term “distal” refers to the portion that is being described which is further from a user, while the term “proximal” refers to the portion that is being described which is closer to a user. 
     In accordance with at least one aspect of the present disclosure, a forceps includes an end effector assembly including first and second jaw members, at least one of the jaw members movable relative to the other between an open position and a closed position for grasping tissue therebetween. The forceps further includes a blade movable between a retracted position wherein the blade is proximal to the jaw members and a deployed position wherein the blade extends at least partially between the jaw members to cut tissue grasped therebetween, a lever member movable between an initial position and a compressed position to move the jaw members between the open and closed positions, and a trigger member operably coupled to the blade and positionable to move the blade between the retracted position and the deployed position, the trigger member defining an actuation path therealong. The forceps also include a trigger safety member pivotably coupled to the lever member such that, when the lever member is disposed in the initial position, the trigger safety member is disposed in a position, blocking actuation of the trigger member and when the lever member is disposed in the compressed position, the trigger safety member is disposed in a position wherein the trigger safety member is displaced from the actuation path to permit movement of the trigger member, wherein the safety member rotates relative to the lever member as a function of movement of the lever member to block/unblock the trigger member. 
     In accordance with another aspect of the present disclosure, the forceps further include a housing enclosing at least a portion of the lever member, the trigger member, and the trigger safety member. 
     In accordance with yet another aspect of the present disclosure, the lever member is operably coupled to the housing at a pivot and the trigger member is operably coupled to the housing at a different pivot. 
     In accordance with yet another aspect of the present disclosure, the lever member and the trigger member are operably coupled to the housing at a single pivot. 
     In accordance with another aspect of the present disclosure, the forceps further include at least one blade deployment member operably coupled to the blade at an engagement pin and to the trigger member about a pivot. 
     In accordance with another aspect of the present disclosure, the forceps further include a drive assembly operably coupled to at least one of the first and second jaw members and positionable to actuate the jaw members between the open position and the closed position. 
     In accordance with another aspect of the present disclosure, the forceps further include at least one driving member operably coupled to the housing, to the trigger safety member, and to the drive assembly at a driving end. 
     In accordance with yet another aspect of the present disclosure, the lever member is operably coupled to trigger safety member about a trigger pivot. 
     In accordance with another aspect of the present disclosure, the forceps further include a latch mechanism configured to releasably secure the lever member in the compressed position. 
     In accordance with yet another aspect of the present disclosure, the trigger safety member is further configured to kickback and forcibly return the trigger member to an un-actuated position. 
     In accordance with another aspect of the present disclosure, the forceps further include a spring to bias the trigger member towards an un-actuated position. 
     In accordance with another aspect of the present disclosure, a forceps include a housing and an end effector assembly including first and second jaw members, at least one of the jaw members movable relative to the other between an open position and a closed position for grasping tissue there between. The forceps further have a blade, the blade movable between a retracted position wherein the blade is proximal to the jaw members and a deployed position wherein the blade extends at least partially between the jaw members to cut tissue grasped therebetween, and a lever member coupled to the housing and to the end effector assembly and movable between an initial position and a compressed position to move the jaw members between the open position and the closed position. The forceps further have a trigger member operably coupled to the housing and coupled to the blade via a blade deployment member, wherein the blade deployment member is operably coupled to the blade at an engagement pin, wherein the trigger member is positionable to move the blade between the retracted position and the deployed position, the trigger member defining an actuation path therealong, a drive assembly operably coupled to at least one of the first and second jaw members to actuate the jaw members between the open position and the closed position, and at least one driving member operably coupled to the housing at a point, to the trigger safety member a different point, and to the drive assembly at a driving end. The forceps also have a trigger safety member pivotably coupled to the lever member such that, when the lever member is disposed in the initial position, the trigger safety member is disposed in a position blocking actuation of the trigger member, and when the lever member is disposed in the compressed position, the trigger safety member is disposed in a position wherein the trigger safety member is displaced from the actuation path to permit movement of the trigger member, wherein the safety member rotates relative to the lever member as a function of movement of the lever member to block/unblock the trigger member. 
     In accordance with another aspect of the present disclosure, the forceps further include a latch mechanism configured to releasably secure the lever member in the compressed position. 
     In accordance with another aspect of the present disclosure, the trigger safety member is further configured to kickback and forcibly return the trigger member to an un-actuated position. 
     In accordance with another aspect of the present disclosure, the forceps further include a spring to bias the trigger member towards an un-actuated position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of the present disclosure are described herein with reference to the drawings, wherein like reference numerals identify similar or identical elements: 
         FIG.  1 A  is a perspective view of a forceps including an end effector assembly in accordance with an aspect of the present disclosure wherein jaw members of the end effector assembly are disposed in a spaced-apart position; 
         FIG.  1 B  is a perspective view of the forceps of  FIG.  1 A  wherein the jaw members of the end effector assembly are disposed in an approximated position; 
         FIG.  2    is a perspective view of a handle assembly of the forceps of  FIG.  1 A  wherein a portion of the housing has been removed to show the internal components therein, the handle assembly including a latch mechanism disposed in an initial position; 
         FIG.  3    is a perspective view of the handle assembly of the forceps of  FIG.  1 A  wherein a portion of the housing has been removed to show the internal components therein and wherein the latch mechanism is disposed in an actuated position; 
         FIG.  4    is an isolated, perspective view of a lever of the latch mechanism of  FIGS.  2  and  3   ; 
         FIG.  5    is an isolated, perspective view of a pin track member and cantilever spring of the latch mechanism of  FIGS.  2  and  3   ; 
         FIG.  6    is a schematic illustration of the use of the latch mechanism of  FIGS.  2  and  3   ; 
         FIG.  7    is a perspective view of the handle assembly of the forceps of  FIG.  1 A  wherein a portion of the housing has been removed to show the internal components therein, the handle assembly including another aspect of a latch mechanism disposed in an actuated position; 
         FIG.  8    is a isolated, perspective view of a pin track member and cantilever spring of the latch mechanism of  FIG.  7   ; 
         FIG.  9    is an isolated, perspective view of a lever of the latch mechanism of  FIG.  7   ; 
         FIG.  10    is a transverse, cross-sectional view of the lever of  FIG.  9   ; 
         FIG.  11    is a schematic illustration of the use of the latch mechanism of  FIG.  7   ; 
         FIG.  12    is a perspective view of a blade in accordance with an aspect of the present disclosure and configured for use with the forceps of  FIG.  1 A ; 
         FIG.  13    is a perspective view of a shaft and a portion of an end effector assembly configured for use with the forceps of  FIG.  1 A ; 
         FIG.  14 A  is a cross-sectional view of the end effector assembly of  FIG.  13    in an open position with the blade in a retracted position; 
         FIG.  14 B  is a cross-sectional view of the end effector assembly of  FIG.  13    in a closed position with the blade in the retracted position; 
         FIG.  14 C  is a cross-sectional view of the end effector assembly of  FIG.  13    in a closed position with the blade in a deployed position; 
         FIG.  15 A  is a side view of a handle and trigger assembly provided in accordance with an aspect of the present disclosure, wherein the lever member is in an initial position and the trigger is locked-out; 
         FIG.  15 B  is a side view of the handle and trigger assembly of  FIG.  15 A  where the lever member is in a transitional state between the initial position and a compressed position; 
         FIG.  15 C  is a side view of the handle and trigger assembly of  FIG.  15 A , wherein the lever member is in the compressed position and the trigger is unlocked; and 
         FIG.  15 D  is a side view of the handle and trigger assembly of  FIG.  15 A , wherein the lever is in the compressed position and the trigger has been activated. 
     
    
    
     DETAILED DESCRIPTION 
     Turning now to  FIGS.  1 A and  1 B , forceps  10  is one example of an instrument for use in accordance with the present disclosure. Forceps  10  including a housing  20 , a handle assembly  30 , a lever latch assembly  40 , a trigger assembly  80 , a rotating assembly  85 , and an end effector assembly  100 . Forceps  10  further includes a shaft  12  having a distal end  14  configured to mechanically engage end effector assembly  100  and a proximal end  16  that mechanically engages housing  20 . Alternatively, any surgical instrument having a lever latch assembly operable to control one or more functions of the end effector assembly may be provided. 
     With continued reference to  FIGS.  1 A and  1 B , end effector assembly  100  includes a pair of opposing jaw members  110  and  120 . End effector assembly  100  is designed as a unilateral assembly, i.e., jaw member  120  is fixed relative to the shaft  12  and jaw member  110  is moveable about a pivot  103  relative to jaw member  120 . However, either, or both jaw members  110 ,  120  may be moveable with respect to the other. In either embodiment, jaw members  110 ,  120  are moveable from a spaced-apart position, as shown in  FIG.  1 A , to an approximated position, as shown in  FIG.  1 B , to grasp tissue therebetween. Further, one or both of jaw members  110 ,  120  may include an electrically conductive tissue sealing surface  112 ,  122 , respectively. Sealing surfaces  112 ,  122  are disposed in opposed relation relative to one another such that, with jaw members  110 ,  120  in the approximated position grasping tissue therebetween, electrosurgical energy may be supplied to one or both of sealing surfaces  112 ,  122  of jaw members  110 ,  120 , respectively, to seal tissue grasped therebetween. 
     One or both of jaw members  110 ,  120  may also include a longitudinally extending blade channel  130  to permit reciprocation of a blade (not shown) therethrough for dividing tissue grasped therebetween. Trigger assembly  80  is operably coupled to the blade (not shown) such that, upon actuation of trigger  82 , the blade (not shown) is translated from a retracted position to an extended position wherein the blade (not shown) is advanced between jaw members  110 ,  120  to cut tissue grasped therebetween. Further, trigger  82  may be biased toward an un-actuated position such that, upon release of trigger  82 , the blade (not shown) is returned to the retracted position. 
     Rotating assembly  85  is integrally associated with housing  20  and is rotatable in either direction about a longitudinal axis “X-X” to rotate jaw members  110 ,  120  with respect to housing  20  about longitudinal axis “X-X.” 
     Handle assembly  30  extends downwardly from housing  20  and is releasably engageable with housing  20 . Handle assembly  30  is ergonomically configured such that, when engaged with housing  20 , a surgeon may grasp handle assembly  30  and operate lever latch assembly  40 , trigger assembly  80  and/or rotating assembly  85  with a single hand. Handle assembly  30  further includes a battery pack (not shown) disposed within a battery housing  32 . The battery pack (not shown) of handle assembly  30  provides power to forceps  10 , e.g., for energizing sealing surfaces  112 ,  122  of jaw members  110 ,  120 , respectively. More particularly, the battery pack (not shown) is configured to electrically couple to a generator (not shown) disposed within housing  20  for powering the generator (not shown). The generator (not shown), in turn, supplies the desired energy to sealing surfaces  112 ,  122  of jaw members  110 ,  120 , respectively, of end effector assembly  100 . Alternatively, forceps  10  may be configured to be coupled to an external power source (not shown) and/or generator (not shown), e.g., via an electrosurgical cable (not shown). 
     With reference to  FIGS.  2  and  3   , in conjunction with  FIGS.  1 A and  1 B , battery housing  32  of handle assembly  30  includes mechanical keying features (not shown) configured complementarily to the mechanical keying features associated with housing  20  such that handle assembly  30  may be securely locked in mechanical engagement with housing  20 . The battery pack (not shown) is electrically coupled to the generator (not shown), and may also be released from housing  20 , e.g., to replace or recharge the battery pack (not shown). 
     Continuing with reference to  FIGS.  2  and  3   , one embodiment of a lever latch assembly  40  is shown including a lever  41  pivotably coupled to housing  20  and extending downwardly therefrom. Lever  41  is ultimately connected to drive assembly  90  that, together, mechanically cooperate to impart movement of jaw members  110  and  120  between the spaced-apart position ( FIG.  1 A ) and the approximated position ( FIG.  1 B ). As mentioned above, spatial constraints within housing  20  limit the positioning of lever  41 , e.g., such that the generator (not explicitly shown) and other control circuitry (not explicitly shown) may be disposed above drive assembly  90  within housing  20 . Further, as will become apparent below, the working components of lever latch assembly  40  are all relatively closely-spaced with respect to one another, thereby providing more area within housing  20  for the generator (not shown) and for engagement of the battery pack (not shown). 
     Continuing with reference to  FIGS.  2  and  3   , lever  41  is selectively moveable from an initial position ( FIG.  2   ), wherein lever  41  is spaced-apart from handle assembly  30 , to an actuated position ( FIG.  3   ), wherein lever  41  is positioned adjacent to handle assembly  30 , to move jaw members  110 ,  120  from the spaced-apart position (see  FIG.  1 A ) to the approximated position (see  FIG.  1 B ). As will be described below, lever latch assembly  40  is configured to permit movement of lever  41  between the initial position ( FIG.  2   ) and the actuated position ( FIG.  3   ) and for releasably locking lever  41  in the actuated position. Accordingly, lever latch assembly  40  is configured to selectively move jaw members  110 ,  120  ( FIGS.  1 A and  1 B ) between the spaced-apart position and the approximated position and to releasably lock jaw members  110 ,  120  ( FIGS.  1 A and  1 B ) in the approximated position. Further, lever  41  may be biased toward the initial position ( FIG.  2   ), such that jaw members  110 ,  120  are biased toward the spaced-apart position ( FIG.  1 A ). 
     Turning now to  FIG.  4   , in conjunction with  FIGS.  2 - 3   , lever  41  of lever latch assembly  40  includes a proximally-extending tab  43 . Tab  43  extends at least partially into housing  20 , e.g., through a slot (not shown) defined therein. More particularly, a proximal tip  44  of tab  43  extends into housing  20  when lever  41  is disposed in the initial position ( FIG.  2   ), while the entire tab  43  (or a substantial portion thereof) extends into housing  20  when lever  41  is moved to the actuated position ( FIG.  3   ). Tab  43  extends into housing  20  above handle assembly  30 , as best shown in  FIGS.  2  and  3   , such that, when the battery pack (not shown) is engaged to housing  20 , tab  43  may still be advanced into housing  20  upon movement of lever  41  from the initial position ( FIG.  2   ) to the actuated position ( FIG.  3   ). 
     A pin  45  is integrally formed with, or fixedly engaged to tab  43  of lever  41  and extends proximally therefrom. Pin  45  may be formed from a metal or other rigid material. As tab  43  is advanced into housing  20  upon movement of lever  41  from the initial position to the actuated position, pin  45  is similarly advanced into housing  20  toward pin track member  46  ( FIG.  5   ). In other words pin  45  is translated along an arc upon movement of lever  41  between the initial position and the actuated position. However, since pin  45  is fixedly engaged within lever  41  and since lever  41  is pivotably engaged to housing  20 , the transverse position of pin  45  relative to housing  20  is fixed. More specifically, pin  45  is transversely aligned with a neutral axis “N-N” ( FIG.  6   ) defined by cantilever spring  47  throughout movement of lever  41  between the initial position and the actuated position. 
     As best shown in  FIG.  5   , pin track member  46  defines a track  50  configured to permit translation of pin  45  therealong. Pin track member  46  is engaged, or integrally formed, e.g., insert molded, with a cantilever spring  47  at a first end  48  of cantilever spring  47 . Cantilever spring  47  is coupled at a second end  49  thereof to housing  20 , e.g., via protrusion-aperture friction fitting, or other suitable engagement. In other words, cantilever spring  47  is fixedly coupled to housing  20  at second end  49  thereof, while first end  48  of cantilever spring  47 , having pin track member  46  disposed thereon, is free. At-rest, cantilever spring  47  is biased toward an aligned position defining the neutral axis “N-N” ( FIG.  6   ). However, cantilever spring  47  is capable of being flexed off of the neutral axis “N-N” ( FIG.  6   ) in both a positive direction “+” ( FIG.  6   ) and a negative direction “−” ( FIG.  6   ). As such, upon urging of pin track member  46  and, thus, the free first end  48  of cantilever spring  47  in either direction relative to the fixed second end  49  of cantilever spring  47 , cantilever spring  47  is flexed off of the neutral axis “N-N” ( FIG.  6   ) such that pin track member  46  is repositioned relative to the neutral axis “N-N” ( FIG.  6   ). Under the bias of cantilever spring  47  toward an aligned position with respect to the neutral axis “N-N” ( FIG.  6   ), pin track member  46  is likewise biased toward an aligned position with respect to the neutral axis “N-N” ( FIG.  6   ). 
     Turning now to  FIG.  6   , in conjunction with  FIGS.  2 - 3   , the operation of lever latch assembly  40  will be described. Initially, with lever  41  disposed in the initial position (and, thus, with jaw members  110 ,  120  disposed in the spaced-apart position ( FIG.  1 A )), pin  45  extends minimally into housing  20 , spaced-apart from pin track member  46 . As shown in  FIG.  6   , this position corresponds to position P 1 . When it is desired to close jaw members  110 ,  120  ( FIG.  1 A ), e.g., for grasping tissue therebetween, the surgeon grasps handle assembly  30  and lever  41  and pulls lever  41  proximally toward handle assembly  30 , i.e., toward the actuated position. As lever  41  is moved from the initial position toward the actuated position, drive assembly  90  imparts movement of jaw members  110 ,  120  from the spaced-apart position to the approximated position. At the same time, as lever  41  is pulled proximally, tab  43  is advanced proximally into housing  20  such that pin  45  is translated, in transverse alignment with neutral axis “N-N,” toward pin track member  46  to position P 2 . However, at this point, pin track member  46  remains aligned on the neutral axis “N-N” under the bias of cantilever spring  47 . 
     Upon further movement of lever  41  toward the actuated position, pin  45  is advanced further proximally into housing  20 , eventually contacting an outer surface  51  of pin track member  46 . With pin  45  transversely fixed with respect to the neutral axis “N-N,” pin  45  causes cantilever spring  47  to be flexed and urges pin track member  46  off of the neutral axis “N-N” in a negative direction “−” as pin  45  is translated through position P 3 . More specifically, the outer surface  51  of pin track member  46  is angled relative to neutral axis “N-N” such that, as lever  41  is pulled further toward the actuated position, pin  45  is slid proximally along outer surface  51  of pin track member  46 , urging pin track member  46  off of the neutral axis “N-N.” 
     Once lever  41  has been moved to the actuated position, corresponding to the approximated position of jaw members  110 ,  120  ( FIG.  1 B ), respectively, of end effector assembly  100 , pin  45  has been slid proximally past angled outer surface  51  of pin track member  46  to a position P 4  adjacent first end  53  of track channel  52  of pin track member  46 . In this position P 4 , with pin  45  no longer contacting outer surface  51  of pin track member  46 , pin  45  no longer urges pin track member  46  off of the neutral axis “N-N.” As such, cantilever spring  47  is flexed back toward the aligned position, thereby moving pin track member  46  back toward alignment with the neutral axis “N-N.” 
     When the actuated position of lever  41  has been achieved, such that jaw members  110 ,  120  ( FIG.  1 B ) are disposed in the approximated position to grasp tissue therebetween, lever  41  is automatically locked in the actuated position to fix jaw members  110 ,  120  ( FIG.  1 B ) in the approximated position. More particularly, once pin  45  is positioned adjacent first end  53  of track channel  52 , cantilever spring  47  biases pin track member  46  back toward the neutral axis “N-N” such that pin  45  is translated along track channel  52  from position P 4  at the first end  53  of track channel  52  to position P 5  at the saddle portion  54  of track channel  52 . Even if lever  41  is released at this point, pin  45  is retained in position within saddle portion  54  of track channel  52  of pin track member  46 . Specifically, pin track member  46  inhibits distal translation of pin  45  and, thus lever  41 , thereby maintaining jaw members  110 ,  120  ( FIG.  1 B ) in the approximated position. Further, with pin  45  disposed in position P 5 , i.e., with pin  45  disposed within saddle portion  54  of track channel  52  of pin track member  46 , pin track member  46  is inhibited from returned into alignment with neutral axis “N-N.” 
     Pin track member  46  may include one or more feedback features (not shown) for providing tactile and/or audible feedback notifying the surgeon that lever  41  has been translated to the actuated position. For example, saddle portion  54  may be configured to provide an audible or tactile response when pin  45  is translated into saddle portion  54 , e.g., when pin  45  is moved to position P 5 . Such a feature indicates to the surgeon that lever latch assembly  40  is in the locked position and that lever  41  may be released to lock jaw members  110 ,  120  in the approximated position. 
     With lever latch assembly  40  maintaining lever  41  in the actuated position and, thus, maintaining jaw members  110 ,  120  ( FIG.  1 B ) in the approximated position with tissue grasped therebetween, electrosurgical energy may be supplied to sealing surfaces  112 ,  122  of jaw members  110 ,  120 , respectively, to effect a tissue seal (see  FIG.  1 B ). Thereafter, trigger  82  may be actuated to advance the blade (not shown) between jaw members  110 ,  120  to cut tissue along the previously formed tissue seal. Finally, lever latch assembly  40  may be unlatched, as described in further detail below, allowing lever  41  to return to the initial position and allowing jaw members  110 ,  120  ( FIGS.  1 A and  1 B ) to return to the spaced-apart position to release tissue such that forceps  10  may be removed from the surgical site. 
     In order to unlock lever latch assembly  40 , lever  41  is moved further proximally from the actuated position a sufficient distance to dislodge pin  45  from saddle portion  54  of track channel  52  of pin track member  46 . In other words, lever  41  is moved proximally such that pin  45  is no longer retained within saddle portion  54 . Track channel  52  is configured such that, once pin  45  is removed from saddle portion  54 , pin  45  enters open second end  55  of track channel  52 . Once pin  45  is moved into the open second end  55  of track channel  52 , e.g., once pin  45  is moved to position P 6 , pin  45  no longer inhibits pin track member  46  from returning under the bias of cantilever spring  47  to the aligned position with respect to neutral axis “N-N.” As such, cantilever spring  47  is returned to the at-rest position, thereby returning pin track member  46  into alignment with neutral axis “N-N.” 
     At this point, with pin  45  in position P 6 , the surgeon may release lever  41 . Similarly as discussed above, pin track member  46  may include feedback features (not shown) for providing a tactile or audible indication to the surgeon that pin  45  has been removed from saddle portion  54  of track channel  52  and, thus, that lever  41  may be released allowing jaw members  110 ,  120  ( FIGS.  1 A and  1 B ) to return to the spaced-apart position. 
     Upon release of lever  41  by the surgeon, lever  41  is returned back to the initial position. As such, pin  45  is translated distally relative to pin track member  46  and housing  20 . More particularly, pin  45  is translated distally from position P 6  along inner surface  56  of pin track member  46 . Inner surface  56  of pin track member  46  is angled such that, as pin  45  is translated therealong to position P 7 , cantilever spring  47  is flexed to permit pin track member  46  to be repositioned off of the neutral axis “N-N” in a positive direction “+.” Upon further distal translation of pin  45  to position P 8 , pin  45  exits second end  55  of track channel  52  of pin track member  46 , allowing pin track member  46  to return under the bias of cantilever spring  47  back into alignment with the neutral axis “N-N.” Thereafter, lever is further returned, e.g., under the bias, back to the initial position corresponding to position P 1  of pin  45  and corresponding to the spaced-apart position of jaw members  110 ,  120  of end effector assembly  100  ( FIGS.  1 A and  1 B ). 
     Turning now to  FIGS.  7 - 9   , another embodiment of a lever latch assembly  60  is shown configured for use with a surgical instrument, e.g., forceps  10 . Similar to lever latch assembly  40  discussed above (see  FIGS.  2 - 6   ), lever latch assembly  60  includes a lever  61  pivotably coupled to housing  20  and extending downwardly therefrom. Lever  61  is ultimately connected to drive assembly  90  that, together, mechanically cooperate to impart movement of jaw members  110  and  120  between the spaced-apart position ( FIG.  1 A ) and the approximated position ( FIG.  1 B ). More particularly, lever  61  is selectively moveable from an initial position, wherein lever  61  is spaced-apart from handle assembly  30 , to an actuated position, wherein lever  61  is positioned adjacent to handle assembly  30 , to move jaw members  110 ,  120  from the spaced-apart position (see  FIG.  1 A ) to the approximated position (see  FIG.  1 B ). 
     With continued reference to  FIGS.  7 - 9   , lever latch assembly  60  is similar to lever latch assembly  40  in that lever latch assembly  60  is configured to permit movement of lever  61  between the initial position and the actuated position and for releasably locking lever  61  in the actuated position. Accordingly, lever latch assembly  60  is configured to selectively move jaw members  110 ,  120  between the spaced-apart position ( FIG.  1 A ) and the approximated position ( FIG.  1 B ) and to releasably lock jaw members  110 ,  120  in the approximated position ( FIG.  1 B ). Further, lever  61  may be biased toward the initial position, such that jaw members  110 ,  120  are biased toward the spaced-apart position ( FIG.  1 A ). 
     As best shown in  FIG.  9   , lever  61  of lever latch assembly  60  includes a pair of flanges  63  extending upwardly therefrom. Flanges  63  extend into housing  20  to couple lever  61  to housing  20 . A crossbar  64  extends between flanges  63  in a generally perpendicular orientation with respect to flanges  63 . A cantilever spring  65  is fixedly engaged at a first end  67  thereof to crossbar  64  and includes a pin  66  integrally formed with, or otherwise engaged to free second end  68  of cantilever spring  65 . Cantilever spring  65  extends downwardly and proximally from crossbar  64  of flanges  63  of lever  61  such that pin  66  extends generally toward housing  20 . More specifically, when lever  61  is disposed in the initial position, pin  66  is spaced-apart from housing  20 . On the other hand, when lever  61  is moved to the actuated position, pin  66  is positioned adjacent housing  20 . Further, cantilever spring  65  is positioned off-center on crossbar  64 , i.e., cantilever spring  65  is positioned asymmetrically between flanges  63  of lever  61 . At-rest, cantilever spring  65  is biased toward an aligned position defining the neutral axis “N-N” ( FIGS.  10  and  11   ). However, cantilever spring  65 , similar to cantilever spring  65 , is capable of being flexed off of the neutral axis “N-N” ( FIGS.  10  and  11   ) in both a position direction “+” and a negative direction “−” to thereby reposition pin  66  off of the neutral axis “N-N” ( FIGS.  10  and  11   ). 
     Referring to  FIGS.  7 - 11   , lever latch assembly  60  also includes a pin track member  69  defining a track  70  configured to permit translation of pin  66  therealong. Pin track member  69  is engaged to, or integrally formed with housing  20  in a generally distal-facing orientation and is positioned to at least partially intersect the neutral axis “N-N.” As such, upon movement of lever  61  from the initial position to the actuated position, pin  66  is translated along an arc toward housing  20  and, thus, toward pin track member  69 , eventually engaging pin track member  69 . As will be described in greater detail below, with pin track member  69  fixedly engaged to housing  20 , and with pin  66  engaged to lever  61  via cantilever spring  65 , movement of lever  61  between the initial position and the actuated position causes pin track member  69  to urge the free second end  68  of cantilever spring  65  off of the neutral axis “N-N” such that pin  66  is repositioned relative to the neutral axis “N-N” to releasably lock lever  61  in the actuated position. 
     The operation of lever latch assembly  60  will now be described. Initially, with lever  61  disposed in the initial position (and, thus, with jaw members  110 ,  120  disposed in the spaced-apart position ( FIG.  1 A )), pin  66  is spaced-apart from pin track member  69  and, thus, cantilever spring  65  is aligned on neutral axis “N-N.” As shown in  FIG.  6   , this position corresponds to position P 1 ′. When it is desired to close jaw members  110 ,  120  ( FIGS.  1 A- 1 B ), e.g., for grasping tissue therebetween, the surgeon grasps handle assembly  30  and lever  61  and pulls lever  61  proximally toward handle assembly  30 , i.e., toward the actuated position. As lever  61  is moved from the initial position toward the actuated position, drive assembly  90  imparts movement of jaw members  110 ,  120  from the spaced-apart position to the approximated position ( FIG.  1 B ). At the same time, as lever  61  is pulled proximally, pin  66  is advanced proximally toward housing  20  such that pin  66  is translated toward pin track member  69 , represented by position P 2 ′. However, at this point, pin  66  is still spaced from pin track member  69  and, thus, remains aligned on the neutral axis “N-N” under the bias of cantilever spring  65 . 
     Upon further movement of lever  61  toward the actuated position, pin  66  is advanced further proximally toward housing  20 , eventually contacting an outer surface  71  of pin track member  69 . Due to the angled configuration of outer surface  71  of pin track member  69  relative to the neutral axis “N-N,” and with pin track member  69  transversely fixed with respect to the neutral axis “N-N,” cantilever spring  65  is flexed and pin  66  is urged of the neutral axis “N-N” in a negative direction “−” as pin  66  is translated through position P 3 ′ and along outer surface  71 . 
     Once lever  61  has been moved to the actuated position, corresponding to the approximated position of jaw members  110 ,  120 , respectively, of end effector assembly  100  ( FIGS.  1 A and  1 B ), pin  66  has been slid proximally past angled outer surface  71  of pin track member  69  to a position P 4 ′ adjacent first end  72  of track channel  74  of pin track member  69 . In this position P 4 ′, with pin  66  no longer contacting outer surface  71  of pin track member  69 , pin track member  69  no longer urges pin  66  off of the neutral axis “N-N.” As such, cantilever spring  65  is flexed back toward the aligned position, thereby moving pin  66  back toward alignment with the neutral axis “N-N.” 
     When lever is moved to the actuated position and is subsequently released, lever latch assembly  60  releasably locks lever  61  in the actuated position to fix jaw members  110 ,  120  in the approximated position (see  FIG.  1 B ). More particularly, once pin  66  is positioned adjacent first end  72  of track channel  74 , cantilever spring  65  biases pin  66  back toward the neutral axis “N-N” such that pin  66  is translated along track channel  74  from position P 4 ′ at the first end  72  of track channel  74  to position P 5 ′ at the saddle portion  75  of track channel  74 . In this position, pin track member  69  inhibits distal translation of pin  66  and, thus lever  61 , thereby maintaining jaw members  110 ,  120  in the approximated position. As in the previous embodiment, pin  66  and/or pin track member  69  may include one or more feedback features (not shown) for providing tactile and/or audible feedback notifying the surgeon that lever  61  has been translated to the actuated position. 
     With lever latch assembly  60  maintaining lever  61  in the actuated position and, thus, maintaining jaw members  110 ,  120  ( FIG.  1 B ) in the approximated position with tissue grasped therebetween, electrosurgical energy may be supplied to sealing surfaces  112 ,  122  of jaw members  110 ,  120 , respectively, to effect a tissue seal (see  FIG.  1 B ). Thereafter, trigger  82  may be actuated to advance the blade (not shown) between jaw members  110 ,  120  ( FIG.  1 B ) to cut tissue along the previously formed tissue seal. Finally, lever latch assembly  60  may be unlatched, as will be described in greater detail below, allowing lever  61  to return to the initial position and allowing jaw members  110 ,  120  ( FIGS.  1 A and  1 B ) to return to the spaced-apart position to release tissue such that forceps  10  may be removed from the surgical site. 
     In order to unlock lever latch assembly  60 , lever  61  is moved further proximally from the actuated position a sufficient distance to dislodge pin  66  from saddle portion  75  of track channel  74  of pin track member  69 . In other words, lever  61  is moved proximally such that pin  66  is no longer retained within saddle portion  75 . Track channel  74  is configured such that, once pin  66  is removed from saddle portion  75 , pin  66  enters open second end  73  of track channel  74 . Once pin  66  is moved into the open second end  73  of track channel  74 , e.g., once pin  66  is moved to position P 6 ′, pin track member  69  no longer inhibits pin  66  from returning under the bias of cantilever spring  65  to the aligned position with respect to neutral axis “N-N.” As such, cantilever spring  65  is returned to the at-rest position, thereby returning pin  66  into alignment with neutral axis “N-N.” At this point, with pin  66  in position P 6 ′, the surgeon may release lever  61 , allowing jaw members  110 ,  120  to return to the spaced-apart position (see  FIG.  1 A ). Upon release of lever  61  by the surgeon, lever  61  is returned back to the initial position. As such, pin  66  is translated distally relative to pin track member  69  and housing  20 . More particularly, pin  66  is translated distally from position P 6 ′ along inner surface  76  of pin track member  69 . Inner surface  76  of pin track member  69  is angled such that, as pin  66  is translated therealong to position P 7 ′, cantilever spring  65  is flexed to permit pin  66  to be repositioned off of the neutral axis “N-N” in a positive direction “+.” Upon further distal translation of pin  66  to position P 8 ′, pin  66  exits second end  73  of track channel  74  of pin track member  69 , allowing pin  66  to return under the bias of cantilever spring  65  back into alignment with the neutral axis “N-N.” Thereafter, lever  61  is further returned, e.g., under the bias, back to the initial position corresponding to position P 1 ′ of pin  66  and corresponding to the spaced-apart position of jaw members  110 ,  120  of end effector assembly  100  ( FIG.  1 A ). 
     Referring to  FIGS.  12 - 14 C , a blade  1200  configured for use with forceps  10  ( FIG.  1 A ), or any other suitable surgical instrument, generally includes a blade  1201  engaged to a blade shaft  1203  having at least one pin hole  1205  defined therein. Blade  1200  is configured for slidable translation within shaft  1307  (similar to shaft  12  of forceps  10  ( FIG.  1 A )) such that blade  1200  may slide through and relative to shaft  1307  between a retracted position and a deployed position, wherein blade  1201  extends at least partially between jaw members  1310 ,  1320  of end effector assembly  1301  (similar to end effector assembly  100  of forceps  10  ( FIG.  1 A )). 
     Referring to  FIGS.  14 A,  14 B and  14 C , shaft  1307  and end effector assembly  1301  are shown incorporating blade  1200  therein. In  FIG.  14 A , jaw members  1310 ,  1320  are disposed in an open position and blade  1201  is disposed in a retracted position. In  FIG.  14 B , jaw members  1310 ,  1320  are disposed in a closed position, while blade  1201  remains disposed in the retracted position. In  FIG.  14 C , jaw members  1310 ,  1320  are in the closed position and the blade  1201  has been deployed to extend at least partially between jaw members  1310 ,  1320 . 
     Turning now to  FIGS.  15 A,  15 B,  15 C, and  15 D , in conjunction with  FIGS.  12 ,  13  and  14 A- 14 C , a handle and trigger assembly  1500  is shown configured to operate blade  1200  and end effector assembly  1301 . Handle and trigger assembly  1500  includes a trigger member  1502  that is pivotably coupled to the housing of the instrument (e.g., housing  20  of forceps  10  ( FIG.  1 A )) at a first pivot  1505 . The trigger member  1502  is operably coupled to a blade deployment member  1510  at a second pivot  1511 . More specifically, second pivot  1511  couples trigger member  1502  to blade deployment member  1510  at one end of blade deployment member  1510 , while engagement pin  1513  couples the other end of blade deployment member  1510  to blade shaft  1203  of blade  1200  via engagement of engagement pin  1513  through a slot  1305  defined within shaft  1307  and into engagement with pinhole  1205  defined within blade shaft  1203 . The slot  1305  defined within shaft  1307  allows translation of engagement pin  1513  so that blade  1200  easily transitions within shaft  1200 , e.g., between the retracted and deployed positions ( FIGS.  14 B and  14 C , respectively). Any of the pivots may be any functional mechanical interface suitable for the desired purpose including, but not limited, to a rotatable connection, a slidable connection, a cam-follower, etc. 
     In operation, as the trigger member  1502  is pulled proximally, from an un-actuated position towards an actuated position, trigger member  1502  is pivoted about first pivot  1505  and blade deployment assembly member  1510  is translated distally such that engagement pin  1513 , which, as mentioned above, is engaged to blade shaft  1203  of blade  1200  via pin hole  1205 , is slid along slot  1305  allowing the blade  1200  to slidably move within shaft  1307 , ultimately to deploy blade  1201  between jaw members  1310 ,  1320  of end effector assembly  1301 , e.g., to move blade  1201  between the retracted and deployed positions ( FIGS.  14 B and  14 C , respectively). Movement of the trigger member  1502  about first pivot  1505  in the other direction, e.g., back towards the un-actuated position, retracts blade  1200 . A spring  1550  disposed about shaft  1307  may function to bias trigger member  1502  distally, such that, upon release of trigger member  1502 , trigger member  1502  is returned distally to the un-actuated position such that blade  1201  is returned to the retracted position. 
     Handle and trigger assembly  1500  further includes a lever member  1544 , at least a portion of which is disposed inside the housing of the instrument (e.g., housing  20  of forceps  10  ( FIG.  1 A )) and operably coupled to the housing via a third pivot. In an embodiment, pivot  1505  functions as both the first and third pivots, e.g., the pivot  1505  for both lever member  1544  and trigger member  1502  as is shown in  FIGS.  15 A- 15 D . Lever member  1544  is configured to move between a first or initial position and a second or compressed position to open and close jaw members  1310 ,  1320  of end effector assembly  1301  in a similar manner as described above with respect to lever  40  and jaw members  110 ,  120  (see  FIGS.  1 A- 11   ). 
     Handle and trigger assembly  1500  further includes driving member  1501  operably coupled to a drive assembly  1590  at a driving end  1507 . The driving member  1501  may be operably connected to the housing (not shown) via at a point, e.g. a fourth pivot  1508 . Driving member  1501  is coupled to end effector assembly  1301  via drive assembly  1590  such that movement of driving member  1501  effects longitudinal translation of drive assembly  1590  which, in turn, effects movement of jaw members  1310 ,  1320  of end effector assembly  1301  between the open and closed positions. Driving end  1507  of driving member  1501  may be operably connected to drive assembly  1590  via engagement of driving end  1507  within mandrel  1592  of drive assembly  1590 . Other suitable connections may also be used. 
     Driving member  1501  is coupled to lever member  1544  such that, upon movement of lever member  1544  from the initial position to the compressed position, driving member  1501  is pivoted about fourth pivot  1508  to urge drive assembly  1590  to translate proximally, thereby moving jaw members  1310 ,  1320  of end effector assembly  1301  from the open position to the closed position to grasp tissue therebetween. Moving lever member  1544  from the compressed position back to the initial position returns jaw members  1310 ,  1320  of end effector assembly  1301  to the open position. A spring  1560  disposed about drive assembly  1590  may function to bias drive assembly  1590  distally such that, upon release of lever member  1544 , lever member  1544  is returned to the initial position and jaw members  1310 ,  1320  are returned to the open position. 
     Handle and trigger assembly  1500  further includes a trigger safety member  1503  that is operably coupled between lever member  1544 , trigger member  1502 , and driving member  1501 . More specifically, trigger safety member  1503  is coupled to lever member  1544  via a fifth or trigger pivot  1506  and to driving member  1501  at a different point, e.g. via a sixth pivot  1504 . Trigger safety member  1503  includes a first portion  1503   a  extending distally from fifth pivot  1506  and a second portion  1503   b  extending proximally from fifth pivot  1506  and coupled to driving member  1501  via sixth pivot  1504 . 
     When the lever member  1544  is in the initial position, as shown in  FIG.  15 A , in conjunction with  FIGS.  12 ,  13  and  14 A- 14 C , trigger safety member  1503  is oriented such that first portion  1503   a  of safety member  1503  blocks, or prevents trigger member  1502  from being actuated. More specifically, first portion  1503   a  of safety member  1503  intercepts the path of trigger member  1502  below first pivot  1505  to prevent pivoting of trigger member  1502  to deploy blade  1201 . This position of safety member  1503  corresponds to a locked state of handle and trigger assembly  1500 . As can be appreciated, in this locked state, safety member  1503  inhibits deployment of blade  1201  when the lever  1544  is not being compressed. Generally, when the lever  1544  is uncompressed, the jaw members  1310 ,  1320  are disposed in the open position, and when the lever  1544  is compressed, the jaw members  1310 ,  1320  are in the closed position. However, the jaw members  1310 ,  1320  may be held in a substantially open position by thick tissue even when the lever  1544  is compressed, in which case the blade  1201  may still be deployed as the safety member  1503  is rotated out of the path of the trigger member  1502  due to the position of the lever  1544 . 
     As shown in  FIG.  15 B , in conjunction with  FIGS.  12 ,  13  and  14 A- 14 C , as lever  1544  is moved from the initial position towards the compressed position to close jaw members  1310 ,  1320 , safety member  1503  begins to rotate about pivot  1506  out of the path of trigger member  1502  so as to no longer block, or inhibit deployment of blade  1201 . The position of the lever  1544  that is required to allow safety member  1503  to no longer block the trigger member  1502  may be selectable as a design feature as desired. For example, the safety member  1503  may block the trigger member  1502  until the lever  1544  is completely compressed. Alternatively, the safety member  1503  may allow the trigger member  1502  to be operated when the lever is at any desired position between the initial position and the compressed position. 
     Turning to  FIG.  15 C , in conjunction with  FIGS.  12 ,  13  and  14 A- 14 C , once lever member  1544  reaches the compressed position, trigger safety member  1503  has already rotated out of the path of trigger member  1502  such that trigger member  1502  may be actuated by the user, e.g., rotated proximally about pivot  1505 , to deploy blade  1201  between jaw members  1310 ,  1320  to cut tissue grasped therebetween. More specifically, as shown in  FIG.  15 C , with lever member  1544  in the compressed position, first portion  1503   a  of safety member  1503  no longer intercepts the path of trigger member  1502 , but, rather, is rotated such that first portion  1503   a  is disposed above pivot  1505 , no longer interfering with the range of motion of trigger member  1502 . This position of safety member  1503  corresponds to an unlocked state of handle and trigger assembly  1500 . 
     Turning to  FIG.  15 D , in conjunction with  FIGS.  12 ,  13  and  14 A- 14 C , with lever member  1544  in the compressed position, and, thus, with handle and trigger assembly  1500  is in the unlocked state, trigger member  1502  may be actuated to deploy blade  1201  between jaw members  1310 ,  1320  of end effector assembly  1301  to cut tissue grasped therebetween. 
     Handle and trigger assembly  1500  may further include a latch mechanism  1546 , similar to any of the latch mechanisms described above (see  FIGS.  1 - 11   ), or any other suitable latch mechanism. Latch mechanism  1546  is configured to releasably retain lever member  1544  in the compressed position, thereby maintaining jaw members  1310 ,  1320  in the closed position. 
     Upon unlatching lever member  1544  from latch mechanism  1546  and returning lever member  1544  towards the initial position (or, simply upon return of lever member  1544 , in instances where latching is not provided or used), safety member  1503  is rotated and translated back towards the locked state. Such a feature is particularly useful in situations where trigger member  1502  is stuck in the deployed position, e.g., where trigger member  1502  does not return under bias of spring  1550  after being released. More specifically, as safety member  1503  is rotated and translated back towards the locked state, first portion  1503   a  contacts trigger member  1502  (if trigger member  1502  has not already been returned under bias to the initial position) and urges trigger member  1502  back towards its initial position, thereby returning blade  1201  to the retracted position. In other words, not only does safety member  1503  provide a “safety lockout” that inhibits deployment of blade  1201  when jaw members  1310 ,  1320  are in the open position, but safety member  1503  also provides a “kickback” feature that returns blade  1201  to the retracted position as jaw members  1310 ,  1320  are returned to the open position. 
     From the foregoing and with reference to the various figure drawings, those skilled in the art will appreciate that certain modifications can also be made to the present disclosure without departing from the scope of the same. While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.