Vessel sealer and divider for large tissue structures

<u>BACKGROUND</u>

0001The present disclosure relates to an electrosurgical forceps and, more particularly, to an endoscopic bipolar electrosurgical forceps for sealing and/or cutting large tissue structures.

<u>Technical Field</u>

0002Electrosurgical forceps utilize both mechanical damping action and electrical energy to affect hemostasis by heating the tissue and blood vessels to coagulate, cauterize and/or seal tissue. Many surgical procedures require cutting and/or ligating large blood vessels and large tissue structures. 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., damping and/ortying-off transected blood vessels or tissue. By utilizing an elongated 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, larger vessels can be more difficult to dose using these standard techniques.

0003In order to resolve many of the known issues described above and other issues relevant to cauterization and coagulation, a recently developed technology has been developed by Valleylab, Inc. of Boulder, Colorado, called vessel or tissue sealing. The process of coadulating vessels is fundamentally different than electrosurgical vessel sealing. For the purposes herein, "coagulation" is defined as a process of desiccating tissue wherein the tissue cells are ruptured and dried. "Vessel sealing" or "tissue sealing" is defined as the process of liquefying the collagen in the tissue so that it reforms into afused mass with limited demarcation between opposing tissue structures. Coagulation of small vessels is sufficientto permanently dose them, white largervessels and tissue need to be sealed to assure permanent closure.

0004In order to ,effectively seal larger vessels (or tissue) two predominant mechanical parameters are accurately controlled -the pressure applied to the vessel (tissue) and the gap distance between the electrodes - both of which are affected by the thickness of the sealed vessel. More particularly, accurate application of pressure is important to oppose the walls of the vessel; to reduce the tissue impedance to a low enough value that allows enough electrosurgical energy through the tissue; to overcome the forces of expansion during tissue heating; and to contribute to the end tissue thickness, which is an indication of a good seal.

0005As mentioned above, in order to properly and effectively seal larger vessels ortissue, a greater closure force between opposing jaw members is required. It is known that a large closure force between the jaws typically requires a large moment about the pivot for each jaw. This presents a design challenge because the jaw members are typically affixed with pins that are positioned to have small moment arms with respect to the pivot of each jaw member. A large force, coupled with a small moment arm, is undesirable because the largeforces may shear the pins. Asa result, designers compensate for these large closure forces by either designing instruments with metal pins and/or by designing instruments that at least partially offload these closure forces to reduce the chances of mechanical failure. As can be appreciated, if metal pivot pins are employed, the metal pins should be insulated to avoid the pin acting as an alternate current path between the jaw members, which may prove detrimental to effective sealing.

0006Increasing the closure forces between electrodes may have other undesirable effects, e.g., it may cause the opposing electrodes to come into close contact with one another, which may result in a short circuit and a small closure force may cause premature movement of the tissue during compression and prior to activation.

0007As a result thereof, providing an instrumentthat consistently provides the appropriate closure force between opposing electrode within a preferred pressure range will enhance the chances of a successful seal. As can be appreciated, relying on a surgeon to manually provide the appropriate closure force within the appropriate range on a consistent basis would be difficult and the resultant effectiveness and quality of the seal may vary. Moreover, the overall success of creating an effectivetissue seal is greatly reliant upon the user's expertise, vision, dexterity, and experience in judging the appropriate closure force to uniformly, consistently and affectively seal the vessel. In other words, the success of the seal would greatly depend upon the ultimate skiii of the surgeon rather than the efficiency of the instrument.

0008It has been found that the pressure range for assuring a consistent and effective seal for large vessels and tissue structures is between about 3 kg/cm² to about 16 kg/cm² and, desirably, within a working range of 7 kg/cm² to 13 kg/cm². As can be appreciated, manufacturing an instrument that is capable of consistently providing a closure pressure within these working ranges is quite a design challenge for instrument manufacturers.

0009Various force-actuating assemblies have been developed in the past for providing the appropriate closure forces to affect vessel sealing. For example, one such actuating assembly has been developed by Valleylab, Inc. of Boulder, Colorado, for use with Valleylab's vessel sealing and dividing instrument for sealing large vessels and tissue structures commonly sold under the trademark LIGASURE ATLAS^®. The LIGASURE ATLAS^® is presently designed to fitthrough a 10mm cannula and includes a bi-lateral jaw closure mechanism and is activated by a foot switch.

0010Other force-actuating assemblies have also been developed by the Valleylab, Inc. of Boulder, Colorado, for use with Valleylab's vessel sealing and dividing instrument for sealing large vessels and tissue structures commonly sold under the trademark LIGASURE 5mm.™ The LIGASURE 5mm™ is presently designed to fit through a 5mm cannula and includes a unilateral jaw closure mechanism and is activated by a hand switch.

0011<patcit id="pcit0001" dnum="US20040254573A"><text>US 2004/0254573 A</text></patcit>, <patcit id="pcit0002" dnum="WO2005004735A1"><text>WO 2005/004735 A1</text></patcit> and <patcit id="pcit0003" dnum="WO2005004734A1"><text>WO 2005/004734 A1</text></patcit> each discloses an endoscopic bipolar forceps for sealing and dividing tissue.

<u>SUMMARY</u>

0012A forceps according to the present invention is defined in claim 1.

0013The forceps includes a housing, a shaft having a longitudinal axis defined therethrough, a drive assembly and a movable handle. The shaft includes an end effector assembly having a pair of jaw members attached to a distal end thereof. The jaw members are movable from a first position in spaced relation to one another to at least a second position doser to one another. The jaw members are for grasping tissue therebetween. Each of the jaw members is adapted to connect to an electrosurgical energy source, thus enabling the jaw members to conduct energy through tissue held between the jaw members to create a tissue seal.

0014The drive assembly moves the jaw members relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members are doser to one another for manipulating tissue. The movable handle is rotatable about a pivot to force a drive flange of the drive assembly to move the jaw members between the first and second positions. In an embodiment, the pivot is located a fixed distance above the longitudinal axis and the drive flange is located generally along the longitudinal axis. This mechanical arrangement creates leve-like mechanical advantage about the pivot to facilitate dosing the jaw members about tissue. The forceps also includes a knife assembly having a generally t-shaped movable knife bar that is dimensioned to operatively engage a corresponding slot defined within the housing. The slot guides the movement of the knife bar during translation thereof.

0015In one embodiment, the knife bar is operatively coupled to a knife slidingly disposed within the shaft. The forceps further includes a finger actuator operatively coupled to the knife assembly wherein movement of the finger actuator moves the knife bar, which, in turn, moves the knife to cut tissue disposed between the jaw members. In another embodiment, the shaft includes a drive sleeve slidingly disposed therein that operatively connects to the drive assembly for moving the jaw members and the knife assembly includes a cuff at the distal end of the knife bar. The cuff is dimensioned to encapsulate and move atop the drive sleeve upon movement of the knife bar. The forceps may also include a finger actuator operatively connected to the knife assembly. The finger actuator includes two generally u-shaped flanges that rotate about a pivot to abut and force the cuff distally, which, in tum, results in distal translation of the knife bar.

0016In yet another embodiment, a spring is included that biases the knife assembly in a proximal-most orientation. A rotating assembly is also included and is configured to rotate the jaw members about the longitudinal axis defined through the shaft. A hand switch may also be included within the housing that is adapted to connect to the source of electrosurgical energy. The hand switch allows a user to selectively supply bipolar energy to the jaw members to affect a tissue seal. At least one of the jaw members includes a series of stop members disposed thereon for regulating the distance between the jaw members during sealing.

0017In an embodiment, the pivot is located a fixed distance above the longitudinal axis and the drive flange is located generally along the longitudinal axis. A trigger assembly is included that is operatively coupled to the housing and operativelycoupledto a knife assembly. The knife assembly includes a drive rod that, upon actuation of the trigger assembly, selectively translates a knife through tissue disposed between the jaw members. A knife guide may also be included that is dimensioned to facilitate alignment and translation of the knife through and into a knife channel defined between the jaw members.

0018In one embodiment, the knife guide includes two engageable halves that insulate the jaw members from one another. The knife guide may also include one or more apertures defined therein that allow the pivot to extend therethrough. The drive assembly may also include a cam pin at a distal end thereof that operatively engages the jaw members and the knife guide may be configured to include one or more slots defined therein that allow the cam pin to extend therethrough.

0019According to the present invention, the pivot includes an aperture defined therein that allows the knife to extend therethrough. The pivot may include a stem and a cap that matingly engage on opposite sides of the shaft to secure the jaw members during assembly.

0020In still yet another embodiment, the trigger assembly selectively translates the knife through tissue disposed between the jaw members and the knife assembly includes a knife carriage having a t-shaped distal end that engages the trigger assembly and a proximal end that engages a knife bar slidingly mounted within the housing. The knife bar may include a cuff at a distal end thereof that defines an aperture located therethrough. The shaft is dimensioned to rotate and slide through the aperture of the cuff.

0021The drive assembly may further include a cam pin that operatively couples the distal end of the drive sleeve to the jaw members for actuation thereof. The knife may be dimensionedto include a slot defined therein that allows the cam pin to extend therethrough.

<u>BRIEF DESCRIPTION OF THE DRAWINGS</u>

0022Various embodiments of the subject instrument are described herein with reference to the drawings wherein: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Fig. 1A</figref> is a perspective view of a bipolar forceps shown in open configuration and including a housing, a shaft, handle assembly, trigger assembly and an end effector assembly according to the present disclosure;</li><li><figref idref="f0002">Fig. 1B</figref> is a perspective view of the bipolar forceps of <figref idref="f0001">Fig. 1A</figref> shown in closed configuration;</li><li><figref idref="f0003">Fig. 2</figref> is a rear view of the forceps of <figref idref="f0001 f0002">Fig. 1</figref> A;</li><li><figref idref="f0004">Fig. 3A</figref> is an enlarged, front perspective view of the end effector assembly of <figref idref="f0001">Fig. 1A</figref> shown in an open configuration;</li><li><figref idref="f0004">Fig. 3B</figref> is an enlarged, front perspective view of the end effector assembly of <figref idref="f0001">Fig. 1A</figref> shown in a closed configuration;</li><li><figref idref="f0005">Fig. 3C</figref> is an enlarged, side view of the end effector assembly of <figref idref="f0001">Fig.1A</figref> shown in open configuration;</li><li><figref idref="f0005">Fig. 3D</figref> is an enlarge, front view of the end effector assembly of <figref idref="f0001">Fig. 1A</figref> shown in open configuration;</li><li><figref idref="f0006">Fig. 3E</figref> is a greatly-enlarged, exploded perspective view of the top jaw member;</li><li><figref idref="f0007">Fig. 3F</figref> is a greatly-enlarged, exploded perspective view of the bottom jaw member;</li><li><figref idref="f0008">Fig. 4</figref> is a perspective view of the endoscopic forceps of <figref idref="f0001">Fig. 1A</figref> with the internal working components of the forceps exposed;</li><li><figref idref="f0009">Fig. 5A</figref> is side view of the endoscopic forceps of <figref idref="f0001">Fig. 1A</figref> with the internal working components of the forceps exposed;</li><li><figref idref="f0010">Fig. 5B</figref> is side view of the endoscopic forceps of <figref idref="f0002">Fig. 1B</figref> with the internal working components of the forceps exposed;</li><li><figref idref="f0011">Fig. 5C</figref> is a greatly-enlarged, perspective view of the handle assembly in open configuration;</li><li><figref idref="f0012">Fig. 5D</figref> is a greatly-enlarged, perspective view of the handle assembly in closed configuration;</li><li><figref idref="f0013">Fig. 6A</figref> is an internal, perspective view of the endoscopic forceps of <figref idref="f0002">Fig. 1B</figref> with the internal working components of the forceps exposed and the trigger shown in an un-actuated position;</li><li><figref idref="f0014">Fig. 6B</figref> is an internal, perspective view of the endoscopic forceps of <figref idref="f0002">Fig. 1B</figref> with the internal working components of the forceps exposed and the trigger shown in an actuated position;</li><li><figref idref="f0020">Fig. 6C</figref> is a schematic representation of the electrical configuration for the trigger assembly;</li><li><figref idref="f0015">Fig. 7</figref> is an internal, side view of the endoscopic forceps of <figref idref="f0002">Fig. 1B</figref> with the trigger shown in an actuated position:</li><li><figref idref="f0016">Fig. 8A</figref> is a side cross-sectional view showing the trigger in an actuated position;</li><li><figref idref="f0017">Fig. 8B</figref> is an enlarged, side cross-sectional view showing the jaw members in a spaced apart orientation;</li><li><figref idref="f0017">Fig. 8C</figref> is an enlarged, side cross-sectional view showing the jaw members in a closed orientation; <figref idref="f0018">Fig. 9A</figref> is side cross-sectional view of the housing showing both the trigger and the handle un-actuated; <figref idref="f0019">Fig. 9B</figref> is side cross-sectional view of the housing showing both the trigger and the handle actuated; <figref idref="f0021">Fig. 10A</figref> is an enlarged, side cross-sectional view showing the end effector in a closed position and the knife in an unactuated position;</li><li><figref idref="f0021">Fig. 10B</figref> is an enlarged, side ctoss-sectional view showing the end effector in a closed position and the knife in an actuated position;</li><li><figref idref="f0022">Fig. 10C</figref> is an enlarged, front perspective view of a bottom jaw member of the end effector assembly showing the knife in an unactuated position;</li><li><figref idref="f0022">Fig. 10D</figref> is an enlarged, front perspective view of the bottom jaw member showing the knife in an actuated position;</li><li><figref idref="f0023">Fig. 11</figref> is an exploded, perspective view of the forceps of <figref idref="f0001">Fig. 1A</figref>;</li><li><figref idref="f0024">Fig. 12</figref> is an enlarged, exploded perspective view of the housing;</li><li><figref idref="f0025">Fig. 13</figref> is an enlarged, exploded perspective view of the end effector assembly and the shaft; and</li><li><figref idref="f0026">Fig. 14</figref> is a greatly enlarged, exploded perspective view of the end effector assembly.</li></ul>

<u>DETAILED DESCRIPTION</u>

0023Turning now to <figref idref="f0001 f0002 f0003">Figs. 1A-2</figref>, one embodiment of a bipolar forceps 10 is shown for use with various surgical procedures and generally includes a housing 20, a handle assembly 30, a rotating assembly 80, a trigger assembly 70 and an end effector assembly 100, which mutually cooperate to grasp, seal and divide large tubular vessels and large vascular tissues. Although the majority of the figure drawings depict a bipolar forceps 10 for use in connection with endoscopic surgical procedures, the present disclosure may be used for more traditional open surgical procedures. For the purposes herein, the forceps 10 is described in terms of an endoscopic instrument; however, it is contemplated that an open version of the forceps may also include the same or similar operating components and features as described below.

0024Forceps 10 includes a shaft 12 that has a distal end 16 dimensioned to mechanically engage the end effector assembly 100 and a proximal end 14 that mechanically engages the housing 20. Details of how the shaft 12 connects to the end effector are described in more detail below with respect to <figref idref="f0025">Figs. 13</figref> and <figref idref="f0026">14</figref>. The proximal end 14 of shaft 12 is received within the housing 20 and the connections relating thereto are also described in detail below with respect to <figref idref="f0023">Figs. 11</figref> and <figref idref="f0024">12</figref>. In the drawings and in the descriptions that follow, the term "proximal," as is traditional, will referto the end of the forceps 10 that is closer to the user, while the term "distal" will refer to the end that is farther from the user.

0025As best seen in <figref idref="f0001">Figs. 1A</figref> and <figref idref="f0003">2</figref>, forceps 10 also includes an electrosurgical cable 310 that connects the forceps 10 to a source of electrosurgical energy, e.g., a generator 500 (shown schematically). Generators such as those sold by Valleylab, located in Boulder, Colorado may be used as a source of electrosurgical energy, e.g., Ligasure™ Generator, FORCE EZ™ Electrosurgical Generator, FORCE FX™ Electrosurgical Generator, FORCE 1C™, FORCE 2™ Generator, SurgiStat™ II or other suitable generators that may perform different or enhanced functions.

0026in one embodiment, the generator500 includes various safety and performance features including isolated output, independent activation of accessories. The electrosurgical generator may include Valleylab's Instant Response™ technology features, which provides an advanced feedback system to sense changes in tissue two hundred times per second and adjust voltage and current to maintain appropriate power. The Instant Response™ technology is believed to provide one or more of the following benefits to surgical procedure: <ul id="ul0002" list-style="bullet"><li>Consistent clinical effect through all tissue types;</li><li>Reduced thermal spread and risk of collateral tissue damage;</li><li>Less need to "turn up the generator": and</li><li>Designed for the minimally invasive environment.</li></ul>

0027Cable 310 is internally divided into cable leads 310a, 310b and 325b (<figref idref="f0020">FIG. 6C</figref>), which are designed to transmit electrical potentials through their respective feed paths through the forceps 10 to the end effector assembly 100. More particularly, cable feed 325b connects through the forceps housing 20 and through the rotating assembly to jaw member 120. Lead 310a connects to one side of the switch 60 and lead 310c connects to the opposite side of the switch 60 such that, upon activation of the switch, energy is transmitted from lead 310a to 310c. Lead 310c is spliced with lead 310b, which connects through the rotating assembly to jaw member 110 (See <figref idref="f0020">Fig. 6C</figref>). Details relating to the electrical connections are explained in more detail below with the discussion of the switch 60.

0028Handle assembly 30 includes a fixed handle 50 and a movable handle 40. Fixed handle 50 is integrally associated with housing 20 and handle 40 is movable relative to fixed handle 50 as explained in more detail below with respect to the operation of the forceps 10. Fixed handle 50 is oriented approximately thirty degrees relative a longitudinal axis "A-A" defined through shaft 12. Fixed handle 50 may include one or more ergonomic enhancing elements to facilitate handling, e.g., scallops, protuberances, elastomeric material etc.

0029Rotating assembly 80 is operatively associated with the housing 20 and is rotatable approximately 180 degrees about a longitudinal axis "A-A" (See <figref idref="f0001">Fig. 1A</figref>). Details of the rotating assembly 80 are described in more detail with respect to <figref idref="f0023">Fig. 11</figref>.

0030As mentioned above, end effector assembly 100 is attached at the distal end 14 of shaft 12 and includes a pair of opposing jaw members 110 and 120. Movable handle 40 of handle assembly 30 is ultimately connected to a drive assembly 130 (<figref idref="f0009">FIG.5A</figref>), which, together, mechanically cooperate to impart movement of the jaw members 110 and 120 from an open position wherein the jaw members 110 and 120 are disposed in spaced relation relative to one another, to a clamping or closed position wherein the jaw members 110 and 120 cooperate to grasp tissue therebetween.

0031Forceps 10 may be designed such that it is fully or partially disposable depending upon a particular purpose or to achieve a particular result. For example, end effector assembly 100 may be selectively and releasably engageable with the distal end 16 of the shaft 12 and/for the proximal end 14 of shaft 12 may be selectively and releasably engageable with the housing 20 and the handle assembly 30. In either of these two instances, the forceps 10 would be considered "partially disposable' or "reposable", i.e., a new or different end effector assembly 100 (or end effector assembly 100 and shaft 12) selectively replaces the old end effector assembly 100 as needed. As can be appreciated, the presently disclosed electrical connections would have to be altered to modify the instrument to a reposable forceps.

0032Turning now to the more detailed features of the present disclosure as described with respect to <figref idref="f0001 f0026">Figs. 1A -14</figref>, movable handle 40 includes a finger loop 43 that has an aperture 41 defined therethrough, which enables a user to grasp and move the handle 40 relative to the fixed handle 50. Finger loop 43 is typically ergonomically enhanced and may includes one or more gripping elements (not shown) disposed along the inner peripheral edge of aperture 41 that are designed to facilitate gripping of the movable handle 40 during activation, e.g., a so called "soft touch" material. Gripping elements may include one or more protuberances, scallops and/or ribs to enhance gripping.

0033As best seen in <figref idref="f0009">Figs. 5A</figref> and <figref idref="f0010">5B</figref>, movable handle 40 is selectively movable about a pivot pin 45 from a first position relative to fixed handle 50 to a second position in closer proximity to the fixed handle 50, which, as explained below, imparts movement of the jaw members 110 and 120 relative to one another. The movable handle includes a clevis 46 that forms a pair of upper flanges 46a and 46b each having an aperture at an upper end thereof for receiving a pivot pin 45 (See <figref idref="f0024">Fig. 12</figref>) therethrough and mounting the upper end of the handle 40 to the housing 20. In turn, pivot pin 45 mounts to respective housing halves 20a and 20b. Pivot pin 45 is -dimensioned to mount within socket 45a of housing half 20b.

0034Each upper flange 46a and 46b also includes a force-actuating flange or drive flange 47a and 47b (See <figref idref="f0015">Fig. 7</figref>), respectively, which are aligned along longitudinal axis "A" and that abut the drive assembly 130 such that pivotal movement of the handle 40 forces actuating flanges 47a and 47b against the drive assembly 130, which, in turn, closes the jaw members 110 and 120 (See <figref idref="f0009">Figs. 5A</figref> and <figref idref="f0010">5B</figref>), For the purposes herein, 47a and 47b that act simultaneously on the drive assembly 13D are referred to as "driving flange 47". A more detailed explanation of the inter-cooperating components of the handle assembly 30 and the drive assembly 130 is discussed below.

0035As best shown in <figref idref="f0011">Fig. 5C</figref>, the lower end of the movable handle 40 includes a flange 42 that is typically integrally associated with or operatively connected to movable handle 40. Flange 42 is typically T-shaped and includes a pin-like element 44 that projects laterally or transversally from a distal end thereof and is configured to engage a corresponding railway 55 disposed within fixed handle 50. More particular, the pin 44 is configured to ride within a pre-defined channel 53 disposed within the railway 55 to lock the movable handle 40 relative to the fixed handle 50 upon reciprocation thereof. Additional features with respect to the t-shaped flange 42 are explained below in the detailed discussion of the operational features of the forceps 10.

0036Movable handle 40 is designed to provide a distinct mechanical advantage overconventional handle assemblies due to the unique position of the pivot pin 45 (i.e., pivot point) relative to the longitudinal axis "A" of the shaft 12 and the disposition of the driving flange 47 along longitudinal axis 'A', In other words, by positioning the pivot pin 45 above the driving flange 47, the user gains lever-like mechanical advantage to actuate the jaw members 110 and 120 enabling the user to close the jaw members 110 and 120 with lesser force while still generating the required forces necessary to effect a proper and effective tissue seal.

0037As shown best in <figref idref="f0004 f0005 f0006 f0007">Figs. 3A-3F</figref>, <figref idref="f0025">13</figref> and <figref idref="f0026">14</figref>, the end effector assembly 100 includes opposing jaw members 110 and 120 that cooperate to effectively grasp tissue for sealing purposes. The end effector assembly 100 is designed as a bilateral assembly, i.e., both jaw members 110 and 120 pivot relative to one another about a pivot pin 95 disposed therethrough. The jaw members 110 and 120 are curved to facilitate manipulation of tissue and to provide better 'line of sight' for accessing organs and large tissue structures.

0038A reciprocating drive sleeve 134 is slidingly disposed within the shaft 12 and is remotely operable by the drive assembly 130 as explained in more detail below. Drive sleeve 134 includes a bifurcated distal end composed of halves 134a and 134b, respectively, which define a cavity 134' therebetween for receiving jaw members 110 and 120. More particularly and as best illustrated in <figref idref="f0025">Figs. 13</figref> and <figref idref="f0026">14</figref>, jaw members 110 and 120 include proximal flanges 113 and 123, respectively, which each include an elongated angled slot 117 and 127, respectively, defined therethrough. A drive pin 139 (See <figref idref="f0025">Fig. 13</figref>) mounts jaw members 110 and 120 to the end of a sleeve 134 and within cavity 134' disposed between flanges 134a and 134b. Cam pin or drive pin 139 mounts through apertures 139a and 139b defined in flanges 134a and 134b, respectively, and is reciprocable within slots 16a' and 16b' disposed at the distal ends 16a and 16b of shaft 12 (See <figref idref="f0026">Fig. 14</figref>). Slots 16a' and 16b' may extend into aperture 95'. and 95" to facilitate assembly of pin 139. Pin 139 may be composed of two mechanical interfacing elements that are dimensioned to frictionally receive one another to retain pin 139 in place once assembled. Alternatively, or in addition, pin 139 may be held in place by one of several known manufacturing techniques including: laseror heat-based welding, press-fit mechanical interaction (or other mechanically interlocking geometry, adhesives, chemical bonding, etc. A component disposed on the outside of shaft 12 may also be utilized to retain the pin 139 in place once assembled. For example, a heat shrink material, adhesive tape, rubber or other insulating boot or silicone may be used for this purpose. A varying diameter version of pin 139 may be utilized to prevent the pin from coming loose once assembled. A cap or stem (not shown) arrangement may also be employed for this purpose as well.

0039Drive-sleeve 134, which ultimately connects to the drive assembly 130, is dimensioned to slidingly receive knife drive rod 193, knife 190 and posts 171a and 171 b of halves 170a and 170b of knife guide 170. Drive sleeve 134, in turn, is received within shaft 12. Upon actuation of the drive assembly 130, the drive sleeve 134 reciprocates, which, in turn, causes the drive pin 139 to ride within slots 117 and 127 to open and close the jaw members 110 and 120 as desired. The jaw members 110 and 120, in turn, pivot about pivot pin 95 disposed through respective pivot holes 113a and 123a disposed within flanges 113 and 123. As can be appreciated, squeezing handle 40 toward handle 50 pulls drive sleeve 134 and drive pin 139 proximally to close the jaw members 110 and 120 about tissue grasped therebetween and pushing the sleeve 134 distally opens the jaw members 110 and 120 for grasping purposes.

0040Turning back to the details of the jaw member 110 and 120 as best shown in <figref idref="f0004 f0005 f0006 f0007">Figs. 3A-3F</figref>, jaw member 110 includes a support base 119 that extends distally from flange 113 and that is dimensioned to support an insulative plate 119'thereon. Insulative plate 119', in turn, is configured to support an electrically conductive tissue engaging surface or sealing plate 112 thereon. The sealing plate 112 may be affixed atop the insulative plate 119' and support base 119 in any suitable manner, such as snap-fit, overmolding, stamping, ultrasonically welded, etc. Support base 119 together with the insulative plate 119' and electrically conductive tissue engaging surface 112 are encapsulated by an outer insulative housing 116. Outer housing 116 includes a cavity 116a that is dimensioned to securely engage the electrically conductive sealing surface 112 as well as the support base 119 and insulative plate 119'. This may be accomplished by stamping, by overmolding, by overmolding a stamped electrically conductive sealing plate and/or by overmolding a metal injection molded seal plate or other suitable methods (e.g., a conductive surface bound to a structural support via an insulating material). All of these manufacturing techniques produce jaw member 110 having an electrically conductive surface 112 that is substantially surrounded by an insulating housing or substrate 116.

0041For example, and as shown in <figref idref="f0006">Fig. 3E</figref>, the electrically conductive sealing plate 112 includes a peripheral flange 112a that surrounds the periphery of the sealing plate 112. Flange 112a is designed to matingly engage an inner lip 116b of the outer insulator 116. Again, this may be accomplished by any of the aforementioned processes, e.g., overmolding. Lead 310b, which extends from switch 60 (See <figref idref="f0020">Fig. 6C</figref>), terminates within the outer insulator 116 and is designed to electro-mechanically couple to the sealing plate 112 by virtue of a crimp-like connection 326a. Insulator 119', electrically conductive sealing surface 112 and the outer, non-conductive jaw housing 116 are preferably dimensioned to limit and/or reduce many of the known undesirable effects related to tissue sealing, e.g., flashover, thermal spread and stray current dissipation.

0042The electrically conductive seating surface 112 may also include an outer peripheral edge that has a pre-defined radius and the outer housing 116 meets the electrically conductive sealing surface 112 along an adjoining edge of the sealing surface 112 in a generally tangential position. At the interface, the electrically conductive surface 112 is raised relative to the outer housing 116.

0043The electrically conductive surface or sealing plate 112 and the outer housing 116, when assembled, form a longitudinally-oriented slot 115a defined therethrough for reciprocation of the knife blade 190 (See <figref idref="f0025">Fig. 13</figref>). Knife slot 115a cooperates with a corresponding knife slot 115b defined in jaw member 120 to facilitate longitudinal extension of the knife blade 190 along a preferred cutting plane to effectively and accurately separate the tissue along the formed tissue seal. Together, knife slots 115a and 115b form knife channel 115 for reciprocation of the knife 190. As best illustrated in <figref idref="f0004 f0005 f0006 f0007">Figs, 3A-3F</figref>, knife channel 115 runs through the center of the jaw members 110 and 120, respectively, such that a blade 190 from the knife assembly 70 can cut the tissue grasped between the jaw members 110 and 120 when the jaw members 110 and 120 are in a closed position. As described in more detail below, handle 30a includes a passive lockout flange 49' that prevents actuation of the knife assembly 70 when the handle 40 is open thus preventing accidental or premature activation of the blade 190 through the tissue. In addition, the passive lockout flange 49' is dimensioned to force the trigger 70 to retract the knife 190 when the handle 40 is moved to an open position.

0044As explained above and as illustrated in <figref idref="f0007">Figs. 3F</figref>, <figref idref="f0017">8B, 8C</figref>.10C and 10D, the knife channel 115 is formed when the jaw members 110 and 120 are closed. In other words, the knife channel 115 includes two knife channel halves-knife slot 115a disposed in sealing plate 112 of jaw member 110 and knife slot 115b disposed sealing plate 122 of jaw member 120. The knife channel 115 may be dimensioned to include some degree of curvature to cause the knife 190 to move through tissue in a curved fashion. Alternatively, the knife channel 115 may be configured as a straight slot with no degree of curvature, which, in turn, causes the knife 190 to move through the tissue in a substantially straight fashion. Insulating plate 119' also forms part of the knife channel 115 and includes slot 115a' defined therein that extends along insulating plate 119' and that aligns in vertical registration with knife slot 115a to facilitate translation of distal end 192 of the knife 190 therethrough.

0045As mentioned above, end effector assembly 100 also includes knife guide 170 that is dimensioned to facilitate alignment and translation of the knife 190 through and into the knife channel 115. More particularly, knife guide 170 includes half 170a and half 170b that mechanically interface to encapsulate the knife 190 upon assembly (See <figref idref="f0025">Fig. 13</figref>). Knife guide 170, once assembled, aligns the knife 190 for facile translation through knife channel 115 upon reciprocation of a knife drive rod 193 (<figref idref="f0025">Fig. 13</figref>). The operation of the drive rod 193 is described below with reference to the operational features of the forceps 10. Each half 170a and 170b of the knife guide 170 includes various interfaces thereon and apertures defined therein that allow unencumbered movement of the various operating features of the end effector assembly 100, e.g., pivot 95, drive pin 139 and knife 190. More particularly, halves 170a and 170b include apertures 173a and 173b, respectively, defined therethrough that allow passage of the pivot 95 during assembly. Halves 170a and 170b also include laterally-aligned slots 172a and 172b defined therein that allow reciprocation of the drive pin 139 upon opening and closing of the jaw members 110 and 120. One or more guides 327 (<figref idref="f0026">Fig. 14</figref>) may also be included to guide leads, e.g., lead 325a, along knife guide 170 and to the electrically conductive plates, e.g., plate 122. Knife guide halves 170a and 170b also include posts 171 a and 171 b that extend proximally into slot 16' upon assembly to engage knife 190.

0046Knife channel 115 runs through the center of the jaw members 110 and 120, respectively, such that a distal end 192 of the knife 190 can cut the tissue grasped between the jaw members 110 and 120 when the jaw members 110 and 120 are in a closed position. More particularly, and as described in more detail below with respect to the operation of the forceps 10, the knife 190 can only be advanced through the tissue when the jaw members 110 and 120 are closed, thus preventing accidental or premature activation of the knife 190 through the tissue. Passive lockoutflange 49' detailed below prevents unintended translation of the knife 190 while the jaw members 110 and 120 are disposed in an open configuration. The knife 190 may be dimensioned to allow other components to pass therethrough, which additionally creates the benefit of enhancing he overall flexibility of the knife to facilitate passage through the knife channel 115.

0047Alternatively, one or both jaw members may also include a safety lockout to prevent the knife 190 from advancing while the jaw members are in an open configuration.

0048Jaw member 120 includes similar elements to jaw member 110, such as jaw housing 126, which encapsulates a support plate 129, an insulator plate 129' and an electrically conductive sealing surface 122. Likewise, the electrically conductive surface 122 and the insulator plate 129', when assembled, include respective longitudinally-oriented knife slots 115b and 115b' defined therethrough for reciprocation of the knife blade 190. As mentioned above, when the jaw members 110 and 129 are closed about tissue, knife slots 115a and 115b form a complete knife channel 115 to allow longitudinal extension of the knife 190 in a distal fashion to sever tissue along a-tissue seal. The knife channel 115 may be completely disposed in one of the two jaw members, e.g., jaw member 120, depending upon a particular purpose. Jaw member 120 may be assembled in a similar manner as described above with respect to jaw member 110. More particularly, the sealing plate 122 may be dimensioned to include an outer peripheral rim 122a that is dimensioned to mechanically interface with an inner lip 126b of housing 126 to secure the sealing plate 122 to the housing 126 with plates 129 and 129' encapsulated therein.

0049As best seen in <figref idref="f0007">Fig. 3F</figref>, jaw member 120 includes a series of stop members 90 disposed on the inner facing surface of the electrically conductive sealing surface 122 to facilitate gripping and manipulation of tissue and to define a gap "G" (<figref idref="f0021">Fig. 10B</figref>) between opposing jaw members 110 and 120 during sealing and cutting of tissue. The series of stop members 90 may be employed on one or both jaw members 110 and 120 depending upon a particular purpose or to achieve a desired result.

0050Jaw member 120 is connected to a second electrical lead 325b extending from switch 60 (See <figref idref="f0014">Fig. 6B</figref>) that terminates within the jaw housing 126 and is designed to electro-mechanically couple to the sealing plate 122 by virtue of a crimp-like connection 326b. As explained in more detail below, leads 310b and 325b allow a userto selectively supply bipolar electrosurgical energy to the jaw members 110 and 120 as needed during surgery.

0051Jaw members 110 and 120 are electrically isolated from one another such that electrosurgical energy can be effectively transferred through the tissue to form a tissue seal. For example, and as best illustrated in <figref idref="f0004 f0005 f0006 f0007">Figs. 3A-3F</figref>, each jaw member 110 and 120 includes a uniquely-designed electrosurgical cable path that transmits electrosurgical energy through the cable leads 310b and 325b to the electrically conductive sealing surfaces 112 and 122, respectively. Cable leads 310b and 325b are held loosely but securely along the cable path to permit rotation of the jaw members 110 and 120. As can be appreciated, this isolates electrically conductive sealing surfaces 112 and 122 from the remaining operative components of the end effector assembly 100 and shaft 12. The two electrical potentials are isolated from one another by virtue of the insulative sheathing surrounding the cable leads 310b and 325b.

0052Jaw members 119 and 120 are engaged to the end of rotating shaft 12 by pivot pin 95 such that rotation of the rotating assembly 80 correspondingly rotates shaft 12 (along with sleeve 134 and knife 190), which, in turn, rotates end effector assembly 100 (See <figref idref="f0001">Fig. 1A</figref>). More particularly, the distal end of rotating shaft 12 is bifurcated to include ends 16a and 16b that define a channel 16' therein for receiving jaw members 110 and 120. Pivot pin 95 includes a stem 95a and cap 95b arrangement that is dimensioned to engage through aperture 95' and 95" disposed in ends 16b and 16a, respectively. Upon assembly and as best illustrated in <figref idref="f0025">Figs. 13</figref> and <figref idref="f0026">14</figref>, the stem 95a of pivot pin 95 extends, in order, through end 16a of shaft 12, aperture 123a of jaw member 120, aperture 173a of half 170a or knife guide 170, aperture 173b of half 170b of knife guide 170, aperture 113a of jaw member 110 and end 16b of shaft 12 to engage cap 95b. Slots 16a' and 16b' are defined within distal ends 16a and 16b and are dimensioned to allow reciprocation of drive pin 139 therein. Stem 95a includes a pass through hole 96 defined therein that allows passage of the knife 190 therethrough for severing tissue while still allowing a large rotational surface area for the jaw members during loading.

0053Turning now to the cooperating components of the housing, <figref idref="f0009">Figs. 5A</figref>, <figref idref="f0010">5B</figref>, <figref idref="f0013">6A</figref>, <figref idref="f0014">6B</figref>, <figref idref="f0023">11</figref> and <figref idref="f0024">12</figref> show the details of the housing 20 and the component features thereof, namely, the drive assembly 130, the rotating assembly 80, the knife actuating assembly 160, the trigger assembly 70 and the handles 40 and 50. More particularly, <figref idref="f0009">Figs. 5A</figref> and <figref idref="f0010">5B</figref> show the above-identified assemblies and components in an assembled form in the housing 20 and <figref idref="f0023">Figs. 11</figref> and <figref idref="f0024">12</figref> show an exploded view of each of the above-identified assemblies and components.

0054As mentioned above and as bestshown in <figref idref="f0023">Figs. 11</figref> and <figref idref="f0024">12</figref>, the proximal end of shaft 12 is mechanically engaged to the housing 20. Housing 20 is formed from two (2) housing halves 20a and 20b, which each include a plurality of interfaces that are dimensioned to mechanically align and engage one another to form housing 20 and enclose the internal working components of forceps 10. As can be appreciated, fixed handle 50 that, as mentioned above, is integrally associated with housing 20, includes halves 50a and 50b that take the shape of handle 50 upon the assembly of the housing halves 20a and 20b.

0055A plurality of additional interfaces (not shown) may disposed at various points around the periphery of housing halves 20a and 20b for ultrasonic welding purposes, e.g., energy direction/deflection points. It is contemplated that ultrasonic welding provides better dimensional stability, strength and joint reliability that other, more traditional, methods. For example, the housing halves may be ultrasonically welded utilizing a combination of a primary weld joint using traditional triangular (or similar) energy directors to form a bonded joint coupled with a secondary hard stop surface (removed from the primary joint surface) for preventing over compression of the joint. A tertiary set of alignment pins may be utilizes throughout the housing halves 20a and 20b, which are configured to both accurately align the halves 20a and 20b during assembly and provide strength and stability during manufacture, handling and transport.

0056Housing halves 20a and 20b (as well as the other components described below) may be assembled together in any suitable fashion. For example, alignment pins, snap-like interfaces, tongue and groove interfaces, locking tabs, adhesive ports, etc. may all be utilized either alone or in combination for assembly purposes.

0057As best seen in <figref idref="f0023">Figs. 11</figref> and <figref idref="f0024">12</figref>, rotating assembly 80 includes two C-shaped halves 80a and 80b that, when assembled, form the rotating assembly 80. Half 80a includes a series of detents/flanges (not shown) that are dimensioned to engage a pair of corresponding sockets or other mechanical interfaces (not shown) disposed within rotating half 80b. Half 80a also includes a tab 84a (phantomly illustrated) that, together with a corresponding tab 84b disposed on half 80b, cooperate to matingly engage slot 80' disposed on shaft 12. As can be appreciated, this permits selective rotation of the shaft 12 about axis "A-A" by manipulating the rotating member 80 in the direction of the arrow "B", which, in turn, rotates the end effector assembly in the direction of arrow "C" (See <figref idref="f0001">Fig. 1 A)</figref>. The rotating assembly may include one or more mechanical interfaces that essentially lock the rotating assembly in a fully counter-clock wise rotational position or a fully clockwise rotational position. This may allow left-handed or right-handed orientations forthe end effector assembly for particular users.

0058As mentioned above, and as best illustrated in <figref idref="f0009">Figs. 5A</figref>, <figref idref="f0010">5B</figref>, <figref idref="f0013">6A</figref> and <figref idref="f0014">6B</figref>, the movable handle 40 includes clevis 46 that forms upper flanges 46a and 46b, which pivot about pins 45a and 45b to pull the reciprocating sleeve 134 along longitudinal axis "A-A" and force driving flanges 47a and 47b against the drive assembly 130, which, in turn, closes the jaw members 110 and 120. The various moving relationships of the flanges 47a and 47b and the drive assembly 130 are explained in more detail below with respect to the operation of the forceps 10. The arrangement of the driving flanges 47a and 47b and the pivot point 45 of the moveable handle 40 provides a distinct mechanical advantage overconventional handle assemblies due to the unique position of the pivot pins 45a and 45b (i.e., pivot point) relative to the longitudinal axis "A-A" of the driving flanges 47a and 47b. In other words, by positioning the pivot pins 45a and 45b above the driving flanges 47a and 47b, the user gains lever-like mechanical advantage to actuate the jaw members 110 and 120. This reduces the overall amount of mechanical force necessary to close the jaw members 110 and 120 to affect a tissue seal.

0059Handle 40 also includes a finger loop 43 that defines opening 41, which is dimensioned to facilitate grasping the handle 40. In one embodiment, finger loop 43 includes a rubber insert that enhances the overall ergonomic "feel" of the handle member40. A locking flange 49' is disposed on the outer periphery of the handle member 40 above the finger loop 43. Locking flange 49' may be designed as a safety lock out mechanism to prevent the triggerassembly 70 from firing when the handle member 40 is oriented in a non-actuated position, i.e., the jaw members 110 and 120 are open. As can be appreciated, this would prevent accidental or premature severing of tissue prior to completion of the tissue seal.

0060Fixed handle 50 includes halves 50a and 50b that, when assembled, form handle 50. Fixed handle 50 includes a channel 51 defined therein that is dimensioned to receive flange 42 in a proximal moving manner when movable handle 40 is actuated. The t-shaped pin 44 of handle 40 is dimensioned forfacile reception within channel 51 of handle 50. Flange 42 may be dimensioned to allow a user to selectively, progressively and/or incrementally move jaw members 110 and 120 relative to one another from the open to closed positions. For example, it is also contemplated that flange 42 may include a ratchet-like interface that lockingly engages the movable handle 40 and, therefore, jaw members 110 and 120 at selective, incremental positions relative to one another depending upon a particular purpose. Othersuitable mechanisms may also be employed to control and/or limit the movement of handle 40 relative to handle 50 (and jaw members 110 and 120) such as, e.g., hydraulic, semi-hydraulic, linear actuator(s), gas-assisted mechanisms and/or gearing systems.

0061As best illustrated in <figref idref="f0012">Figs. 5D</figref> and <figref idref="f0024">12</figref>, housing halves 20a and 20b, when assembled, form an internal cavity 52 that predefines the channel 51 within fixed handle 50 adjacent the railway 55, which reciprocates t-shaped pin 44 therein. Once assembled, the railway 55 is seated within cavity 52 in registration with entrance pathway 51 for reciprocation of the flange 42. Flange 42 and the housing halves 20a and 20b are designed to facilitate accurate and consistent reception of the t-shaped pin 44 into railway 55.

0062During movement of the flange 42 along the entrance to channel 51, the t-shaped pin 44 rides through passage 53 along railway 55 and is forced into a catch basin or seat 55' to lock the handle 40 relative to handle 50. When the user releases the handle 40. the catch basin 55' retains the t-shaped pin 44 in a secured position relative to the handle 50 as explained in further detail below. Railway 55 may be seated on one or pivot elements 55a that allows the railway 55 to pivot upon reception ofthet-shaped pin 44therethrough. A spring element 57 biases the railway 55 to return to the original reception position once the t-shaped pin 44 is seated. The railway 55, again, may pivot in response to release of the t-shaped pin 44 from catch basin 55'. Actuation of the handle 40 along with the inter-cooperating elements of the drive assembly 130 close the jaw members 110 and 120 about tissue with a predeterminable and consistent closure pressure to effect a tissue seal. As mentioned above, closure pressures for sealing large tissue structures preferably tall within the range of about 3kg/cm² to about 16 kg/cm².

0063When handle 40 is regrasped, the t-shaped pin 44 is forced out of or disengaged from the catch basin 55' and moves along an exit pathway to release handle 40 from channel 51. A spring or other biasing member 57 may be employed to facilitate securing the flange 42 within the catch basin 55' and also configured to facilitate release of the flange 42 from catch basin 55' upon re-grasping of the handle 40.

0064As explained in more detail below, once actuated, handle 40 moves in a generally arcuate fashion towards fixed handle 50 about pivot pins 45a and 45b, which forces driving assembly 130 proximally that, in turn, pulls reciprocating sleeve 134 in a generally proximal direction to close jaw members 110 and 120 relative to one another.

0065As best shown in <figref idref="f0009">Figs. 5A</figref>, <figref idref="f0010">5B</figref> and <figref idref="f0023">11</figref>, the drive assembly 130 mounts atop the proximal portion of the drive sleeve 134. A pair of retaining rings or clips 131' and 131" (See <figref idref="f0023">Fig. 11</figref>) cooperate with a corresponding pair of relieved portions 133a and 133b disposed on the drive sleeve 134 to mount the drive assembly 130 atop the drive sleeve 134 such that relative movement of the drive assembly correspondingly moves the drive sleeve 134. As handle 40 pivots about pivot point 45 and moves relative to handle 50 and flange 42 is incorporated into channel 51 of fixed handle 50, the driving flanges 47a and 47b, through the mechanical advantage of the above-the-center pivot point, force the drive assembly 130 proximally against spring 131.

0066As a result thereof, drive sleeve 134 reciprocates proximally, which, in turn, closes the jaw members 110 and 120. The utilization of an over-the-center pivoting mechanism will enable the user to selectively compress the coil spring 131 a specific distance, which, in turn, imparts a specific load on the reciprocating sleeve 134 that is converted to a rotational torque about the jaw pivot pin 95. As a result, a specific closure force can be transmitted to the opposing jaw members 110 and 120.

0067<figref idref="f0009">Figs. 5A</figref> and <figref idref="f0010">5B</figref> show the initial actuation of handle 40 towards fixed handle 50 that causes the pin 44 of flange 42 to move general ly proximally and upwardly along entrance pathway 51. During movement of the flange 42 along the entrance pathway 51, respectively, the t-shaped pin 44 rides through passageway 53 along railway 55 as explained above. Once the desired position for the sealing site is determined and the jaw members 110 and 120 are properly positioned, handle 40 may be compressed fully such that the t-shaped pin 44 of flange 42 seats within catch basin 55'. Once pin 44 clears an edge or passes a predetermined point in the passageway 53 at the edge of the catch basin 55', releasing movement of the handle 40 and flange 42 is redirected into a catch basin 55'.

0068More particularly, upon a slight reduction in the closing pressure of handle 40 against handle 50, the handle 40 returns slightly distally towards entrance pathway 51 but is re-directed to seat within catch basin 55'. At this point, the release or return pressure between the handles 40 and 50, which is attributable and directly proportional to the release pressure associated with the compression of the drive assembly 130, causes the pin 44 of flange 42 to settle or lock within catch basin 55'. Handle 40 is now secured in position within fixed handle 50, which, in turn, locks the jaw members 110 and 120 in a closed position, against the tissue.

0069As mentioned above, the jaw members 110 and 120 may be opened, closed and rotated to manipulate tissue until sealing is desired. This enables the user to position and re-postion the forceps 10 prior to activation and sealing. As illustrated in <figref idref="f0001">Fig. 1A</figref>, the end effector assembly 100 is rotatable about longitudinal axis "A-A" through rotation of the rotating assembly 80. As explained in more detail below, the unique feed path of the cable leads 325a and 325b through the rotating assembly 80, along shaft 12 and, ultimately, to the jaw members 110 and 120 enables the user to rotate the end effector assembly 100 about 180 degrees across the clockwise and counterclockwise directions without tangling or causing undue strain on cable leads 325a and 325b. As can be appreciated, this facilitates the grasping and manipulation of tissue.

0070As best shown in <figref idref="f0009">Figs. 5A</figref>, <figref idref="f0010">5B</figref>, <figref idref="f0013">6A</figref>, <figref idref="f0018">9A</figref>, <figref idref="f0019">9B</figref>, <figref idref="f0023">11</figref> and <figref idref="f0024">12</figref>, trigger assembly 70 mounts atop movable handle 40 and cooperates with the knife assembly 160 to selectively translate knife 190 through a tissue seal. More particularly, the trigger assembly 70 includes a U-shaped finger actuator 71 having a pair upwardly-extending flanges 71 a and 71 b. A pivot pin 179 extends through a pair of apertures 162a and 162b in each of the flanges 71 a and 71 b, respectively, to mount the trigger assembly 70 to a knife carriage 165, as explained in more detail below. Finger actuator 71 is selectively pivotable within a pre-defined slot 21 disposed within housing 20 (See <figref idref="f0013">Fig. 6A</figref>). More particularly, a pair of pivots 77a and 77b is disposed on either side of the finger actuator 71 and are configured to mount between housing halves 20a and 20b to pivot the finger actuator within slot 21.

0071The knife assembly 160 includes a reciprocating knife bar 167 that mounts atop the drive sleeve 134 and between upwardly extending flanges 71 a and 71 b. Knife bar 167 includes a t-shaped proximal end 167' and a cuff 137 disposed at the distal end thereof. Cuff 137 is dimensioned to encapsulate drive sleeve 134 when the knife assembly 160 is assembled. A spring 76 biases the cuff in a proximal-most orientation. Proximal end 167' is dimensioned to mount and slidingly reciprocate within a slot 167" formed by housings 20a and 20b at assembly (See <figref idref="f0024">Fig. 12</figref>). A locking cap 137a and a mounting pin 179 secure the cuff 137 to the proximal end 193b of the knife rod 193 through aperture 197 disposed therein such that proximal movement to the finger actuator 71 results in distal movement of the knife bar 193. Cuff 137 and cap 137a also allow 360 degrees of rotation of the drive sleeve 134 therethrough.

0072As mentioned above, a knife carriage 165 mounts to the upwardly extending flanges 71 a and 71b of the finger actuator 71. More particularly, the distal end 162 of the knife carriage 165 is t-shaped and includes two laterally extending pins 162c and 162d that engage apertures 162a and 162b, respectively, in flanges 71a and 71 b. The proximal end 161 of the knife carriage 165 includes an aperture 161 a defined therein that mates with a detent 167a that extends transversally through knife carriage 165.

0073As best illustrated in <figref idref="f0009 f0010 f0011 f0012 f0013 f0014 f0015">Figs. 5A-7</figref>, when the handle 40 is disposed in aspaced-apartoropen configuration relative to handle 50, flange 49', which extends from handle 40, prevents actuation of the trigger assembly 70. More particularly, finger actuator 71 is prevented from being actuated proximally by flange 49' when the jaw members 110 and 120 are open. As can be appreciated, this prevents premature actuation of the knife 190 when tissue is not grasped between jaw members 110 and 120. When handle 40 is selectively moved relative to handle 50, a gap 21 is formed between the flange 49' and the finger actuator 71 (See <figref idref="f0010">Fig. 5B</figref>). Thus, the user is free to selectively actuate the knife 190 by squeezing the finger actuator 71 proximally within gap 21.

0074As best shown in <figref idref="f0014">Figs. 6B</figref>, <figref idref="f0015">7</figref> and <figref idref="f0016">8A</figref>, once the clearance is provided by movement of handle 40, proximal movement of the finger actuator 71 about pivot 74 results in distal translation of the knife bar 167, which, in turn, results in distal translation of the knife rod 193 and knife 190. More particularly, when finger actuator 71 is squeezed proximally, the U-shaped flanges 71 a and 71 b rotate about pivot 74 to abut cuff 137 and essentially throw the knife carriage 165 forward, which, in turn, carries the knife bar 167 forward to force the knife rod 193 distally. Slot 167" is configured to smoothly guide the knife bar 167 distally through the forward and return stroke. As shown in <figref idref="f0021">Figs. 10A</figref> and <figref idref="f0021 f0022">10BC</figref>, distal translation of the knife rod 193 translates the knife 190 through channel 115 in the jaw members 110 and 120. As mentioned above, the knife rod 193 mounts the knife 190 via one or more mechanically interfacing elements or may be affixed in any known manner in the art. A slot 197 defined within the knife 190 provides clearance for pin 139 of the drive sleeve 134 during reciprocation of the knife 190. Upon release of finger actuator 71, spring 76 biases the knife assembly back to a proximal-most position. The knife bar 167 provides variable mechanical advantage and linear advantage when triggering the knife 190. In addition, the incorporation of the knife bar 167 significantly reduces friction loss and provides smoother mechanical cutting than previously known methods.

0075Turning now in detail to the operation of the drive assembly as best seen in <figref idref="f0009">Figs. 5A</figref>, <figref idref="f0010">5B</figref>, <figref idref="f0023">11</figref> and <figref idref="f0024">12</figref>, drive assembly 130 includes reciprocating sleeve 134, drive housing 135, spring 131, drive rings 135a and 135b, drive stops 135c and 135d and retaining rings 131' and 131 ", which all cooperate to form the drive assembly 130. Stop 135c may be removed and ring 131' would perform stop 135c's intended function. The proximal end 132 of the reciprocating steeve 134 is positioned within an aperture 135' defined through the drive housing 135 to permit selective reciprocation of the drive sleeve 134 therethrough upon actuation of the movable handle 40. The spring 131 is assembled atop the drive housing 135 between a rear stop 135d and ring 135b such that movement handle 40 about pivot 45 moves the entire drive assembly 130 and sleeve 134 proximally, which, in turn, pulls cam pin 139 proximally to close the jaw members 110 and 120. Once the jaw members 110 and 120 close about tissue, the drive assembly 130 essentially bottoms out (i.e., further proximal movement of the reciprocating sleeve is prevented) and further movement of handle 40 about pivot 45 compresses spring 131 resulting in additional closure force on the tissue. Moreover, spring 131 also tends to bias the jaw members 110 and 120 and the movable handle 40 in an open configuration.

0076Turning back to <figref idref="f0024">Fig. 12</figref>, which shows the exploded view of the housing 20, rotating assembly 80, trigger assembly 70, movable handle 40 and fixed handle 50, all of these various component parts along with the shaft 12 and the end effector assembly 100 are assembled during the manufacturing process to form a partially and/or fully disposable forceps 10. For example and as mentioned above, the shaft 12 and/or end effector assembly 100 may be disposable and, therefore, selectively/releasably engageable with the housing 20 and rotating assembly 80 to form a partially disposable forceps 10 and/or the entire forceps 10 may be disposable after use.

0077As best seen in <figref idref="f0009">Figs. 5A</figref>, <figref idref="f0010">5B</figref> and <figref idref="f0025">13</figref>, once assembled, spring 131 is poised for compression atop drive housing 135 upon actuation of the movable handle 40. More particularly, movement of the handle 40 aboutpivot pins 45a and 45b reciprocates the flange 42 into fixed handle 50 and forces drive assembly 130 to compress spring 131 against the rear stop 135d to reciprocate the sleeve 134.

0078As mentioned above, the trigger assembly 70 is initially prevented from firing by the locking flange 49' disposed on movable handle 40, which abuts against the trigger assembly 70 prior to actuation. The opposing jaw members 110 and 120 may be rotated and partially opened and closed without unlocking the trigger assembly 70, which, as can be appreciated, allows the user to grip and manipulate the tissue without premature activation of the knife assembly 160. As mentioned below, only when the t-shaped pin 44 of flange 42 is completely reciprocated within channel 51 of the fixed handle 50 and seated within pre-defined catch basin 55' will the locking flange 49' allow full activation of the trigger assembly 70. The operating features and relative movements of these internal working components of the forceps 10 are shown by phantom representation and directional arrows and are best illustrated in the various figures.

0079The mechanical advantage of the over-the-center pivot may enable the userto selectively compress the coil spring 131 a specific distance, which, in turn, imparts a specific load on the reciprocating sleeve 134. The reciprocating sleeve's 134 load is converted to a torque about the jaw pivot 95. As a result, a specific closure force can be transmitted to the opposing jaw members 110 and 120. As mentioned above, the jawmembers 110 and 120 may be opened, closed and rotated to manipulate tissue until sealing is desired without unlocking the trigger assembly 70. This enables the userto position and re-position the forceps 10 priorto activation and sealing. More particularly, as illustrated in <figref idref="f0001">Fig. 1A</figref>, the end effector assembly 100 is rotatable about longitudinal axis "A-A" through rotation of the rotating assembly 80.

0080Once the desired position forthe sealing site is determined and the jaw members 110 and 120 are properly positioned, handle 40 may be compressed fully such that the t-shaped pin 44 of flange 42 clears a pre-defined railway edge located atop the railway 55. Once end 44 clears the railway edge, the end 44 is directed into catch basin 55' to lock the handle 40 relative to handle 50. The release or return pressure between the handles 40 and 50, which is attributable and directly proportional to the release pressure associated with the compression of the drive assembly 130, causes the end 44 of flange 42 to settle or lock within catch basin 55'. Handle 40 is now secured in position within fixed handle 50, which, in turn, locks the jaw members 110 and 120 in a closed position against the tissue.

0081At this point the jaws members 110 and 120 are fully compressed about the tissue. Moreover, the forceps 10 is now ready for selective Application of electrosurgical energy and subsequent separation of the tissue, i.e., as t-shaped end 44 seats within catch basin 55', locking flange 49' moves into a position to permit activation of the trigger assembly 70.

0082As the t-shaped end 44 of flange 42 seats within catch basin 55', a proportional axial force on the reciprocating sleeve 134 is maintained, which, in turn, maintains a compressive force between opposing jaw members 110 and 120 against the tissue. The end effector assembly 100 and/or the jaw members 110 and 120 may be dimensioned to off-load some of the excessive clamping forces to prevent mechanical failure of certain internal operating elements of the end effector 100.

0083As can be appreciated, the combination of the mechanical advantage of the over-the-center pivot along with the compressive force associated with the compression spring 131 facilitate and assure consistent, uniform and accurate closure pressure about the tissue within the desired working pressure range of about 3 kg/cm² to about 16 kg/cm² and, desirably, about 7 kg/cm² to about 13 kg/cm². By controlling the intensity, frequency and duration of the electrosurgical energy applied to the tissue, the user can treat tissue, i.e., seal tissue.

0084As mentioned above, two mechanical factors play an important role in determining the resulting thickness of the sealed tissue and effectiveness of the seal, i.e., the pressure applied between opposing jaw members 110 and 120 and the gap distance "G" between the opposing sealing surfaces 112, 122 of the jaw members 110 and 120 during the sealing process. However, thickness of the resulting tissue seal cannot be adequately controlled by force alone. In other words, too much force and the two jaw members 110 and 120 would touch and possibly short resulting in little energy traveling through the tissue thus resulting in a bad tissue seal 450. Too little force and the seal would be too thick.

0085Applying the correct force is also important for other reasons: to oppose the walls of the vessel; to reduce the tissue impedance to a low enough value that allows enough current through the tissue; and to overcome the forces of expansion during tissue heating in addition to contributing towards creating the required end tissue thickness, which is an indication of a good seal.

0086In one embodiment, the electrically conductive sealing surfaces 112 and 122 of the jaw members 110 and 120, respectively, are relatively flat to avoid current concentrations at sharp edges and to avoid arcing between high points. In addi6on and due to the reaction force of the tissue when engaged, jaw members 110 and 120 can be manufactured to resist bending. For example, the jaw members 110 and 120 may be tapered along the width thereof, which is advantageous for two reasons: 1) the taper will apply constant pressure for a constant tissue thickness at parallel; 2) the thicker proximal portion of the jaw members 110 and 120 will resist bending due to the reaction force of the tissue.

0087As mentioned above, at least one jaw member, e.g., 120, may include one or more stop members 90 that limit the movement of the two opposing jaw members 110 and 120 relative to one another. In one embodiment, the stop members 90 extend from the sealing surface 122 a predetermined distance according to the specific material properties (e.g., compressive strength, thermal expansion, etc.) to yield a consistent and accurate gap distance "G" during sealing (<figref idref="f0021">Fig. 10B</figref>). It is envisioned forthe gap distance between opposing sealing surfaces 112 and 122 during sealing ranges from about 0.001 inches to about 0.006 inches and, desirably, between about 0.002 and about 0.005 inches. In one embodiment, the non-conductive stop members 90 are molded onto the jaw members 110 and 120 (e.g., overmolding, injection molding, etc.), stamped onto the jaw members 110 and 120 or deposited (e.g., deposition) onto the jaw members 110 and 120. For example, one technique involves thermally spraying a ceramic material onto the surface of the jaw member 110 and 120 to form the stop members 90. Several thermal spraying techniques are contemplated that involve depositing a broad range of heat resistant and insulative materials on various surfaces to create stop members 90 for controlling the gap distance between electrically conductive surfaces 112 and 122.

0088As energy is being selectively transferred to the end effector assembly 100, across the jaw members 110 and 120 and through the tissue, a tissue seal forms isolating two tissue halves. Atthis point and with other known vessel sealing instruments, the user may remove and replace the forceps 10 with a cutting instrument (not shown) to divide the tissue halves along the tissue seal. As can be appreciated, this is both time consuming and tedious and may result in inaccurate tissue division across the tissue seal due to misalignment or misplacement of the cutting instrument along the ideal tissue cutting plane.

0089As explained in detail above, the present disclosure incorporates knife assembly 160 that, when activated via the trigger assembly 70, progressively and selectively divides the tissue along an ideal tissue plane in a precise manner to effectively and reliably divide the tissue into two sealed halves. The knife assembly 160 allows the userto quickly separate the tissue immediately after sealing without substituting a cutting instrument through a cannula or trocar port. As can be appreciated, accurate sealing and dividing of tissue is accomplished with the same forceps 10.

0090Knife blade 190 may also be coupled to the same or an alternative electrosurgical energy source to facilitate separation of the tissue along the tissue seal. Moreover, the angle of the trip of the knife blade 190 may be dimensioned to provide more or less aggressive cutting angles depending upon a particular purpose. For example, the knife blade 190 may be positioned at an angle that reduces tissue wisps" associated with cutting. Moreover, the knife blade 190 may be designed having different blade geometries such as serrated, notched, perforated, hollow, concave, convex etc. depending upon a particular purpose or to achieve a particular result, The knife assembly 160 generally cuts in a progressive, unidirectional fashion (i.e., distally).

0091Once the tissue is divided into tissue halves, the jaw members 110 and 120 may be opened by re-grasping the handle 40 as explained below. Re-initiation or re-grasping of the handle 40 again moves t-shaped pin 44 of flange 42 generally proximally.

0092As best shown in <figref idref="f0025">Fig. 13</figref>, the proximal portions of the jaw members 110 and 120 and the distal end 16 of shaft 12 may be covered by a resilient or flexible insulating material 185 to reduce stray current concentrations during electrosurgical activation. The tail or proximal end of the jaw members 110 and 120 may be removed and covered with an extended section of the guide element 170 creating a semi insulative barrierto reduce stray current concentrations during electrosurgical activation. An insulating boot (not shown) may also be positioned atop the proximal portions of the jaw members 110 and 120 to further reduce current concentrations and stray currents from damaging adjacent tissue. Details relating to one envisioned insulating boot 220 are described with respectto commonly-owned <patcit id="pcit0004" dnum="US722213P" dnum-type="L"><text>U.S. Provisional Application Serial No. 60/722,213</text></patcit> entitled "INSULATING BOOT FOR ELECTROSURGICAL FORCEPS", which is incorporated by reference herein.

0093Switch 60 is ergonomically dimensioned and conforms to the outer shape of housing 20 (once assembled). Switch 60 is designed to electromechanicaliy cooperate with a flex circuit 400 (See <figref idref="f0020">Fig. 6C</figref>) to allow a user to selectively activate the jaw members 110 and 120. It is contemplated that a flex circuit design facilitates manufacturing due to the circuit unique ability to conform as needed into tightly spaced areas. The switch 60 may also permit the userto selectively activate the forceps 10 in a variety of different orientations, i.e., multi-oriented activation or toggle-like activation. As can be appreciated, this simplifies activation. Switch 60 may also be designed as a so called "dome switch", which also provides tactile feedback to the user when activated.

0094When switch 60 is depressed, trigger lead 310b carries the first electrical potential to jaw member 110 thus completing a bipolar circuit. More particularly, when switch 60 is depressed and flex circuit 400 is activated, the generator recognizes a voltage drop across leads 310a and 310c, which initiates activation of the generator to supply a first electrical potential to jaw member 110 and a second electrical potential to jaw member 120. Switch 60 acts as a control circuit and is protected or removed from the actual current loop that supplies electrical energy to the jaw members 110 and 120. This reduces the chances of electrical failure of the switch 60 due to high current loads during activation. A footswitch (not shown), which may also be utilized with the forceps 10, also operates in asimilarmanner, i.e., upon activation of the footswitch, the generator recognizes a voltage drop across the input and output leads of the footswitch, which, in turn, signals the generator to initiate electrosurgical activation of the jaw members 110 and 120.

0095A safety switch or circuit (not shown) may be employed such that the switch cannot fire unless the jaw members 110 and 120 are closed and/or unless the jaw members 110 and 120 have tissue held therebetween.

0096In the latter instance, a suitable sensor (not shown) may be employed to determine if tissue is held therebetween. In addition, other sensor mechanisms may be employed that determine pre-surgical, concurrent surgical (i.e., during surgery) and/or post surgical conditions. The sensor mechanisms may also be utilized with a closed-loop feedback system coupled to the electrosurgical generator to regulate the electrosurgical energy based upon one or more pre-surgical, concurrent surgical or post surgical conditions.

0097The conductive surfaces 115a and 115b are electrically isolated from one another and jaw members 110 and 120 such that electrosurgical energy can be effectively transferred through the tissue to form the seal. The cable leads 31 0b and 325b are held loosely but securely along the cable path to permit rotation of the jaw members 110 and 120 about longitudinal axis "A" (See <figref idref="f0001">Fig 1A</figref>). More particularly, cable leads 310b and 325b are fed through respective halves 80a and 80b of the rotating assembly 80 in such a manner to allow rotation of the shaft 12 (via rotation of the rotating assembly 80) in the clockwise or counter-clockwise direction without unduly tangling or twisting the cable leads 310b and 325b. The presently disclosed cable lead feed path may allow rotation of the rotation assembly approximately 180 degrees in either direction.

0098From 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. For example, it may be preferable to add other features to the forceps 10, e.g., an articulating assembly to axially displace the end effector assembly 100 relative to the elongated shaft 12.

0099It is also contemplated that the forceps 10 (and/orthe electrosurgical generator used in connection with the forceps 10) may include a sensor or feedback mechanism (not shown) that automatically selects the appropriate amount of electrosurgical energy to effectively seal the particularly-sized tissue grasped between the jaw members 110 and 120. The sensor or feedback mechanism may also measure the impedance across the tissue during seating and provide an indicator (visual and/or audible) that an effective seal has been created between the jaw members 110 and 120.

0100Moreover, the trigger assembly 70 may include other types of recoil mechanism that are designed to accomplish the same purpose, e.g., gas-actuated recoil, electrically-actuated recoil (i.e., solenoid), etc. The forceps 10 may also be used to cut tissue without sealing. Alternatively, the knife assembly 70 may be coupled to the same or alternate electrosurgical energy source to facilitate cutting of the tissue.

0101The outer surface of the end effector assembly 100 may include a nickel-based material, coating, stamping, metal injection molding that is designed to reduce adhesion between the jaw members 110 and 120 with the surrounding tissue during activation and sealing. Moreover, the conductive surfaces 112 and 122 of the jaw members 110 and 120 may be manufactured from one (or a combination of one or more) of the following materials: nickel-chrome, chromium nitride, MedCoat 2000 manufactured by The Electrolizing Corporation of OHIO, inconel 600 and tin-nickel. The tissue conductive surfaces 112 and 122 may also be coated with one or more of the above materials to achieve the same result, i.e., a "non-stick surface". As can be appreciated, reducing the amount that the tissue "sticks" during sealing improves the overall efficacy of the instrument.

0102One particular class of materials disclosed herein has demonstrated superior non-stick properties and, in some instances, superior seal quality. For example, nitride coatings that include, but not are not limited to: TiN, ZrN, TiAIN, and CrN are preferred materials used for non-stick purposes. CrN has been found to be particularly useful for non-stick purposes due to its overall surface properties and optimal performance. Other classes of materials have also been found to reducing overall sticking. For example, high nickel/chrome alloys with a Ni/Cr ratio of approximately 5:1 have been found to significantly reduce sticking in bipolar instrumentation. One particularly useful non-stick material in this class is Inconel 600. Bipolar instrumentation having sealing surfaces 112 and 122 made from or coated with Ni200, Ni201 (-100% Ni) also showed improved non-stick performance over typical bipolar stainless steel electrodes.

0103As can be appreciated, locating the switch 60 on the forceps 10 has many advantages. For example, the switch 60 reduces the amount of electrical cable in the operating room and eliminates the possibility of activating the wrong instrument during a surgical procedure due to "line-of-sight" activation. Moreover, the switch 60 may be configured such that it is mechanically or electromechanically decommissioned during trigger activation to eliminate unintentionally activating the device during the cutting process. The switch 60 may also be disposed on another part of the forceps 10, e.g., the fixed handle 50, rotating assembly 80, housing 20, etc.

0104The forceps 10 may be equipped with an automatic, electro-mechanical release mechanism (not shown) that releases the tissue once an end seal is determined (i.e., end-tone signal from the generator). For example, an electromechanical interface may be configured to automatically release the t-shaped pin 44 from catch basin 55 upon an end tone condition.

0105It is also contemplated that the forceps 10 may be dimensioned to include a trigger assembly 70 that operates in lieu of the switch assembly 60 to activate the forceps to seal tissue while also advancing the knife 190 to divide the tissue across the seal. For example, the trigger assembly 70 could be configured to have two stages: a first or initial stroke stage that activates the generator to selectively seal tissue; and a second or subsequent stage that advances the knife through the tissue. Alternatively, another embodiment may include a trigger assembly that simultaneously activates the jaw members 110 and 120 to seal tissue and advances the knife 190 through the tissue during activation.

0106The rotating assembly 80 may be equipped with one or more mechanical interfaces that are rotatable with or within the rotating assembly 80 and that are configured to produce tactile and/or audible feedback to the user during rotation. The tactile and/or audible feedback (i.e., a "click") may be configured to correspond to a particular degree of rotation of the end effector assembly 100 about the axis "A". It is also contemplated that one or more types of visual indicia may also be employed with the rotating assembly 80 to correspond to the amount or degree of rotation of the end effector assembly 100 and may be designed correspond to or relate to the audible and/or tactile feedback depending upon a particular purpose.

0107Another version of the forceps 10 may include a telescoping shaft that allows the user to selectively regulate the length of the instrument for particular surgical purposes. For example, the shaft may include two slidingly reciprocatable and extendible elements that, upon exertion (i.e., pulling, twisting, or by virtue of a mechanical lever on the handles), either lengthen or shorten the size of the elongated shaft 12 depending upon a particular surgical purpose.

0108Moreover, it is also contemplated that the diameter of shaft 12 may be selectively expandable depending upon a particular surgical purpose or to provide rigidity of the forceps 10 inside the surgical cavity or to enhance the sealing effect of the shaft through a trocar. More particularly, it is contemplated that the shaft 12 may be configured to expand upon exertion (i.e., twisting or rotating one element inside another (iris-like), sliding a mechan-ical lever, an inflatable system, a mechanically expanding system or other types of known expansion systems). As a result, the surgeon can selectively expand the outer diameter of the shaft 12 to enhance the rigidity of the shaft 12 within a trocar and/or enhance the seating effect of the shaft 12 within the trocar to reduce the possibility of pressure leakage from surgical cavity during use. Moreover, a single forceps may be selectively adaptable to work with differently-sized trocars and/or cannulas, which may prove advantageous for particular operations and other surgical procedures.

0109It is also contemplated that the forceps 10 may be configured such that handle 50 is selectively replaceable or selectively positionable depending upon user preference. For example, handle 50 may be selectively detached and replaced with another handle 50 that is of different dimension (i.e., size, weight, angle, orientation to user's hand, etc.), which facilitates handling during surgical procedures. Alternatively, handle 50 may be selectively positionable relative to the housing 20 (i.e., the angle of the handle to the housing is adjustable) to facilitate handling and use during particular surgical procedures or for user comfort.

0110The forceps may be configure to include a visual indicator (which cooperates with the "end tone" indicator on the generator) to provide visual confirmation of a successful seal (e.g., a green LED indicator). The visual indicator (not shown) may be employed on or in connection with the end effector assembly 100 or shaft 12 that is in line-of-site of the surgeon during use. The visual indicator may also be designed to warn the user of a mis-seal condition or a re-grasp condition (e.g., a red LED indicator). Alternatively, the visual indicator may also be configured to provide progressive feedback of the formation of the seal during the sealing process. For example, a series of LEDs may be employed on the end effector assembly 100 (or shaft 12) that progressively illuminate through the sealing process to provide visual feedback to the user regarding the status of the seal. Moreover, one or both jaw members may include visual markings that indicate the end of a seal and/or the length of the seal cut.

0111The guide element 170 (See <figref idref="f0026">Fig. 14</figref>) may be configured to not only guide the knife 190 into the knife channel 115 disposed between the jaw members 110 and 120, but may also be dimensioned to precisely space the jaw members 110 and 120 relative to one another about the pivot 95. Moreover, the guide element 170 may be configured to include one or more grooves of tracks (not shown) to guide the electrical connections or wires 310b and 325b through the end effector assembly 100. The guide element 170 may also be configured to limit the distal movement of the drive rod 193 for the knife 190, which, in turn, limits the overall travel of the knife 190 through the knife channel 115. The distal end of the guide element may be extended to work with the over-molded jaw elements 116 and 126 to create a set of tissue blocking features that inhibit tissue from getting behind or moving proximal to the active electrode surface.

0112The stem 95a of the pivot pin 95 may include a stepped diameter that securely compresses the jaw members 110 and 120 together when mechanically secured with the cap 95b. Moreover, the pivot may be dimensioned to include a pass through or aperture 96 that allows translation of the knife therethrough. The two-piece pivot 95 including stem 95a and cap 95b may be assembled during the manufacturing process by any one of several known manufacturingtechniques including: laser or heat-based welding, press-fit mechanical interaction (or other mechanically interlocking geometry, adhesieves, chemical bonding, etc.

0113The shaft may be dimensioned to enhance visibility and/or non-symmetric depending upon a particular purpose. For example, it is contemplated that the shaft may be generally oval in dimension thereby providing uni-directional strength in one dimension versus another and maximized visibility to the operating site in one direction versus another. Alternatively, the shaft may be other geometric configurations depending upon a particular purpose, I-beam, square, polygonal, etc.

0114The end effector assembly 100 is optimized for reengaging long tissue sections and visibility of the operating site. The jaw members 110 and 120 may also be dimensioned to include distal ends configured for gross or blunt dissection.

0115While 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 of the claims appended hereto.