US20030181910A1 - Bipolar electrosurgical forceps with non-conductive stop members - Google Patents

Abstract

A bipolar forceps for clamping and sealing tissue includes at least one elongated shaft having opposing jaw members at a distal end thereof which are movable 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 cooperate to grasp tissue therebetween. The forceps is also connected to a source of electrical energy which, in turn, connects to each jaw member to the source of electrosurgical energy such that the jaw members are capable of conducting energy through tissue held therebetween. At least two non-conductive and spaced-apart stop members are disposed on an inner facing surface of the jaw members to control the gap distance between the jaw member(s) when tissue is held therebetween.

Description

CROSS REFERENCE TO RELATED APPLICATION
• This application is a continuation of U.S. application Ser. No. 09/621,029 filed on Jul. 21, 2000 which is a continuation of U.S. application Ser. No. 09/177,950 filed on Oct. 23, 1998 the contents of which are hereby incorporated by reference in their entirety.[0001]
BACKGROUND
• The present disclosure relates to an electrosurgical instrument for performing open and/or endoscopic surgical procedures. More particularly, the present disclosure relates to a bipolar electrosurgical forceps which includes a non-conductive stop member associated with one or both of the opposing jaw members which is designed to control the gap distance between opposing jaw members and enhance the manipulation and gripping of tissue during the sealing process.[0002]
TECHNICAL FIELD
• A hemostat or forceps is a simple plier-like tool which uses mechanical action between its jaws to constrict vessels and is commonly used in open surgical procedures to grasp, dissect and/or clamp tissue. Electrosurgical forceps utilize both mechanical clamping action and electrical energy to effect hemostasis by heating the tissue and blood vessels to coagulate, cauterize and/or seal tissue.[0003]
• Over the last several decades, more and more surgeons are complimenting traditional open methods of gaining access to vital organs and body cavities with endoscopes and endoscopic instruments which access organs through small puncture-like incisions. Endoscopic instruments are inserted into the patient through a cannula, or port, that has been made with a trocar. Typical sizes for cannulas range from three millimeters to twelve millimeters. Smaller cannulas are usually preferred, and this presents a design challenge to instrument manufacturers who must find ways to make surgical instruments that fit through the cannulas.[0004]
• Certain surgical procedures require cutting blood vessels or vascular tissue. However, due to space limitations surgeons can have difficulty suturing vessels or performing other traditional methods of controlling bleeding, e.g., clamping and/or tying-off transected blood vessels. Blood vessels, in the range below two millimeters in diameter, can often be closed using standard electrosurgical techniques. If a larger vessel is severed, it may be necessary for the surgeon to convert the endoscopic procedure into an open-surgical procedure and thereby abandon the benefits of laparoscopy.[0005]
• Several journal articles have disclosed methods for sealing small blood vessels using electrosurgery. An article entitled[0006]Studies on Coagulation and the Development of an Automatic Computerized Bipolar Coagulator,J. Neurosurg.,Volume 75, July 1991, describes a bipolar coagulator which is used to seal small blood vessels. The article states that it is not possible to safely coagulate arteries with a diameter larger than 2 to 2.5 mm. A second article is entitledAutomatically Controlled Bipolar Electrocoagulation-“COA-COMP”, Neurosurg. Rev. (1984), pp.187-190, describes a method for terminating electrosurgical power to the vessel so that charring of the vessel walls can be avoided.
• By utilizing an electrosurgical forceps, a surgeon can either cauterize, coagulate/desiccate and/or simply reduce or slow bleeding, by controlling the intensity, frequency and duration of the electrosurgical energy applied to the tissue. Generally, the electrical configuration of electrosurgical forceps can be categorized in two classifications: 1) monopolar electrosurgical forceps; and 2) bipolar electrosurgical forceps.[0007]
• Monopolar forceps utilize one active electrode associated with the clamping and effector and a remote patient return electrode or pad which is typically attached externally to the patient. When the electrosurgical energy is applied, the energy travels from the active electrode, to the surgical site, through the patient and to the return electrode.[0008]
• Bipolar electrosurgical forceps utilize two generally opposing electrodes which are disposed on the inner opposing surfaces of the end effectors and which are both electrically coupled to an electrosurgical generator. Each electrode is charged to a different electric potential. Since tissue is a conductor of electrical energy, when the effectors are utilized to grasp tissue therebetween, the electical energy can be selectively transferred through the tissue.[0009]
• In order to effect a proper seal with larger vessels, two predominant mechanical parameters must be accurately controlled—the pressure applied to the vessel and the gap between the electrodes both of which affect thickness of the sealed vessel. More particularly, accurate application of the 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. It has been determined that a fused vessel wall is optimum between 0.001 and 0.005 inches. Below this range, the seal may shred or tear and above this range the lumens may not be properly or effectively sealed.[0010]
• Electrosurgical methods may be able to seal larger vessels using an appropriate electrosurgical power curve, coupled with an instrument capable of applying a large closure force to the vessel walls. It is thought that the process of coagulating small 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 and vessel sealing is defined as the process of liquefying the collagen in the tissue so that it reforms into a fused mass. Thus, coagulation of small vessels is sufficient to permanently close them. Larger vessels need to be sealed to assure permanent closure.[0011]
• Numerous bipolar electrosurgical forceps have been proposed in the past for various open surgical procedures. However, some of these designs may not provide uniformly reproducible pressure to the blood vessel and may result in an ineffective or non-uniform seal. For example, U.S. Pat. No. 2,176,479 to Willis, U.S. Pat. Nos. 4,005,714 and 4,031,898 to Hiltebrandt, U.S. Pat. Nos. 5,827,274, 5,290,287 and 5,312,433 to Boebel et al., U.S. Pat. Nos. 4,370,980, 4,552,143, 5,026,370 and 5,116,332 to Lottick, U.S. Pat. No. 5,443,463 to Stern et al., U.S. Pat. No. 5,484,436 to Eggers et al. and U.S. Pat. No. 5,951,549 to Richardson et al., all relate to electrosurgical instruments for coagulating, cutting and/or sealing vessels or tissue.[0012]
• These instruments rely on clamping pressure alone to procure proper sealing thickness and are not designed to take into account gap tolerances and/or parallelism and flatness requirements which are parameters which, if properly controlled, can assure a consistent and effective tissue seal. For example, it is known that it is difficult to adequately control thickness of the resulting sealed tissue by controlling clamping pressure alone for either of two reasons: 1) if too much force is applied, there is a possibility that the two poles will touch and energy will not be transferred through the tissue resulting in an ineffective seal; or 2) if too low a force is applied, a thicker less reliable seal is created.[0013]
• As mentioned above, in order to properly and effectively seal larger vessels, 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 challenge because the jaw members are typically affixed with pins which are positioned to have a 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 large forces may shear the pins. Moreover and with particular respect to endoscopic procedures, it may also be undesirable to increase the moment arm of the pins because the physical size of the jaw members and other component parts might not fit through a cannula.[0014]
• Moreover, increasing 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 pre-mature movement of the issue during compression and prior to activation.[0015]
• Thus, a need exists to develop a bipolar forceps which effectively seals vascular tissue and solves the aforementioned problems by providing an instrument which produces a large closure force between the opposing jaws members, reduces the chances of short circuiting the opposing jaws during activation and assists in manipulating, gripping and holding the tissue prior to and during activation.[0016]
SUMMARY
• The present disclosure relates to a bipolar forceps for clamping and sealing tissue for use in open or endoscopic surgical procedures. The forceps includes at least one elongated shaft having opposing jaw members at a distal end thereof. The jaw members are movable 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 cooperate to grasp tissue therebetween. The forceps connect to a source of electrical energy which, in turn, connects to each jaw member such that the jaw members are capable of conducting energy through tissue held therebetween. At least two nonconductive and spaced-apart stop members are disposed on an inner-facing surface of the jaw members to control the gap distance between the jaw members when tissue is held therebetween.[0017]
• In one embodiment, the stop members include a series of longitudinally-oriented projections which extend along the inner-facing surface from the proximal end to the distal end of the jaw member. In another embodiment, the stop members include a series of circle-like tabs which project from the inner facing surface and extend from the proximal end to the distal end of the jaw member. Each of the stop members may be centrally disposed along the width of the jaw member, or, alternatively, the stop members may be disposed in an alternating, laterally-offset manner relative to one another along the length of the surface of the jaw member.[0018]
• In another embodiment of the present disclosure, a raised lip acts as a stop member which projects from the inner-facing surface and extends about the outer periphery of the jaw member to control the gap distance between jaw members. In another embodiment, a longitudinally-oriented ridge extends from the proximal end to the distal end of one of the jaw members and controls the gap distance between the jaw members.[0019]
• The stop members are affixed/attached to the jaw member(s) by stamping, thermal spraying, overmolding and/or by an adhesive. Preferably, the stop members project about 0.001 inches to about 0.005 inches and, preferably, about 0.002 inches to about 0.003 inches from the inner-facing surface of at least one of the jaw members. It is envisioned that the stop members may be made from an insulative material such as parylene, nylon and/or ceramic.[0020]
• Another embodiment of the present disclosure includes a bipolar forceps having a drive rod assembly which electrically connects the jaw members to the source of electrical energy such that the first jaw member has a first electrical potential and the second jaw member has a second electrical potential. A handle is attached to the drive rod assembly for imparting movement of the first and second jaw members relative to one another from the first and second positions. At least two spaced-apart stop members are disposed on the inner-facing surface of the jaw member(s) for regulating the overall gap distance between the jaw members at closing.[0021]
• Another embodiment of the present disclosure relates to a bipolar forceps which includes a pair of elongated shafts each having a jaw member at a distal end thereof and a finger ring at a proximal end thereof. Movement of the finger rings imparts movement of the jaw members relative to one another from the first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue therebetween. The first shaft connects to the source of electrical energy to supply the first jaw member to a first electrical potential and the second shaft connects the second jaw member to a second electrical potential such that the jaw members are capable of conducting energy through the tissue held therebetween. At least two spaced-apart stop members are disposed on the inner facing surface of the jaw member(s) for controlling the gap distance between the jaw members.[0022]
BRIEF DESCRIPTION OF THE DRAWINGS
• Various embodiments of the subject instrument are described herein with reference to the drawings wherein:[0023]
• FIG. 1 is a perspective view of an endoscopic forceps according to the present disclosure;[0024]
• FIG. 2 is an enlarged, perspective view of an end effector assembly of the forceps of FIG. 1;[0025]
• FIG. 3 is a perspective view with parts separated of a handle assembly and activator of the forceps of FIG. 1;[0026]
• FIG. 4 is an enlarged, perspective view with parts separated of the end effector assembly and a drive rod assembly of the forceps of FIG. 1;[0027]
• FIG. 5A is a side, partial cross-section of the handle assembly and drive rod assembly of the forceps of FIG. 1;[0028]
• FIG. 5B is an enlarged, side cross-section of the indicated area of detail shown in FIG. 5A;[0029]
• FIG. 6 is a perspective view of the handle assembly, activator and drive rod assembly of the forceps of FIG. 1;[0030]
• FIG. 7 is an enlarged, partial cross-section of the end effector assembly shown with a pair of jaw members in the open configuration;[0031]
• FIG. 8 is an enlarged, partial cross-section showing the linear motion of the drive rod assembly against a cam follower of the end effector assembly to effect closure of the jaw members;[0032]
• FIG. 9 is a perspective view of the forceps showing the rotational movement of a rotating assembly which rotates the end effector assembly about a longitudinal axis “A”;[0033]
• FIG. 10 is an enlarged perspective view of the indicated area of detail shown in FIG. 9;[0034]
• FIG. 11 is a perspective view of the forceps of the present disclosure shown sealing a tubular vessel through a cannula assembly;[0035]
• FIG. 12 is an enlarged perspective view of a sealing site of a tubular vessel;[0036]
• FIG. 13 is a longitudinal cross-section of the sealing site taken along line[0037]13-13 of FIG. 12;
• FIG. 14 is a longitudinal cross-section of the sealing site of FIG. 12 after separation of the tubular vessel;[0038]
• FIG. 15A is a perspective view of an open forceps according to the present disclosure;[0039]
• FIG. 15B is an enlarged view of the forceps of FIG. 15A; and[0040]
• FIGS.[0041]16A-16G are enlarged, perspective views showing alternative embodiments of a non-conductive stop member disposed on or along the inner-facing surface of one of the jaw members.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• Referring now to FIGS.[0042]1-3, one embodiment ofbipolar forceps10 is shown for use with endoscopic surgical procedures and includes adrive rod assembly11 which is coupled to ahandle assembly18. Thedrive rod assembly11 includes an elongatedhollow shaft portion12 having aproximal end16 and adistal end14. In the drawings and in the descriptions which follow, the term “proximal”, as is traditional, will refer to the end of thebipolar forceps10 which is closer to the user, while the term “distal” will refer to the end which is further from the user. In addition, although the majority of the figures, i.e., FIGS.1-14, show one embodiment of the presently described instrument for use with endoscopic surgical procedures, e.g.,forceps10, it is envisioned that the same inventive concepts as shown and described herein may also be employed with or incorporated on an opensurgical instrument100 such as the embodiment shown by way of example in FIGS. 15A and 15B.
• An[0043]end effector assembly22 is attached to thedistal end14 ofshaft12 and includes a pair of opposingjaw members80 and82. Preferably, handleassembly18 is attached to theproximal end16 ofshaft12 and includes anactivator20 which imparts movement of thejaw members80 and82 from an open position wherein thejaw members80 and82 are disposed in spaced relation relative to one another, to a clamping or closed position wherein thejaw members80 and82 cooperate to grasp tissue150 (FIG. 12) therebetween.
• As best seen in FIG. 3,[0044]activator20 includes amovable handle26 having anaperture34 defined therethrough for receiving at least one of the operator's fingers and a fixedhandle28 having anaperture32 defined therethrough for receiving an operator's thumb.Movable handle26 is selectively moveable from a first position relative to fixedhandle28 to a second position in closer proximity to the fixedhandle28 to closejaw members80 and82. Preferably, fixedhandle28 includes achannel27 which extends proximally for receiving aratchet30 which is coupled tomovable handle26.Ratchet30 allows a user to selectively, progressively and incrementally movejaw members80 and82 relative to one another from the open to closed positions. As can be appreciated, ratchet30 also allows a user to lockingly engage themovable handle26 and, therefore,jaw members80,82 at incremental positions relative to one another prior to and/or during activation. In some cases it may be preferable to include other mechanisms to control and/or limit the movement ofhandle26 relative to handle28 andjaw members80 and82 such as, e.g., hydraulic, semi-hydraulic and/or gearing systems.
• Fixed[0045]handle28 includes a rotatingassembly23 for controlling the rotational movement ofend effector assembly22 about a longitudinal axis “A” of the elongated shaft12 (see FIGS. 9 and 10). Preferably, rotatingassembly23 includes upper andlower knob portions24aand24b, respectively, which mechanically interface one another to enclose agear52 which is attached toshaft12. Preferably, the ratio of rotation of rotatingassembly23 to endeffector assembly22 is 1:1, however, it is contemplated that a different gearing structure may be incorporated to increase or decrease the rotational ratio depending upon a particular purpose, e.g., worm gears, gear trains, etc.
• Preferably, a pair of[0046]handle sections28aand28bengage one another by way of a plurality of mechanical interfaces to form fixedhandle28. The mechanical interfaces includesockets138 which are formed in handle section28band which are dimensioned to receive a complimentary plurality of detents (not shown) attached to handlesection28a. While the term socket is used herein, it is contemplated that either a male or female mechanical interface may be used on either handle section e.g.,28awith a mating mechanical interface disposed on the opposite handle section, e.g.,28b.
• As best seen in FIG. 3, each[0047]handle section28aand28bis generally hollow such that acavity50 is formed therein for housing the various internal-working components which make up theforceps10. For example,cavity50 houses aPC board58 which transfers electrosurgical energy transmitted from an electrosurgical generator (not shown) to eachjaw member80 and82. Aplug62 connects to the electrosurgical generator and transmits electrosurgical energy to the PC board via acable60 which is fed to forceps10 through awire port29 disposed in the proximal end ofhandle assembly28.
• Preferably, a lost motion mechanism is positioned between each of the[0048]handle sections28aand28bfor maintaining a predetermined or maximum clamping force for sealing tissue between thejaw members80 and82. In the particular embodiment shown in FIG. 3, the lost motion mechanism comprises aresilient arm40 which is connected betweenhandle sections28aand28bbypin42. More particularly, thearm40 includes alower end46, anupper end45 andshaft portion47 located therebetween. Preferably,upper end45 is bifurcated and forms a clevis having upwardly extendingflanges49aand49b, respectively.Lower end46 is dimensioned to engage a step-like interface48 located onmovable handle portion26. Theshaft portion47 is seated within apivot slot55 located towards the upper end ofhandle26 such that theshaft portion47 is housed within anelongated channel56 formed withinmovable handle portion26. Preferably, acover plate31 attaches tomovable handle26 by conventional means, e.g., snap-fit engagement to securearm40 withinhandle26.
• Referring to FIG. 4,[0049]rod assembly11 includes adrive rod70 which has aproximal end71 and adistal end72. Aball contact38 is attached to theproximal end71 ofdrive rod70 and includes a generally roundedhead portion39 and anotch41 located between thehead portion39 and the proximal end ofball contact38. Preferably, clevisflanges49aand49bofarm40 are dimensioned to receivehead39 therebetween whenarm40 is assembled betweenhandle sections28aand28b(see FIG. 6). Movement of thehandle26 towards fixedhandle28 imparts pivotal movement of theupper end45 ofarm40 at pivot slot55 (see FIG. 5A) which, in turn, imparts movement of theball contact38 from a first position wherein theball contact38 is disposed further fromend effector assembly22 to a second position whereinball contact38 is in closer proximity to end effector assembly22 (see FIG. 5B). As explained in greater detail below, movement of theball contact38 between first and second positions imparts linear movement to driverod70 which, in turn, movesjaw members80 and82 toward and away from each other.
• As can be appreciated by the present disclosure, seating the generally rounded[0050]head39 betweenclevis flanges49aand49benables the user to utilize the rotatingassembly23 effectively without interfering with the linear movement of theball contact38.
• As best seen in the exploded view of FIG. 4, the[0051]end effector assembly22 includesfirst jaw80,second jaw82 and an electrically insulatingyoke84 disposed therebetween. Preferably,jaw member80 andjaw member82 are movable from the open position to the closed position by movement of thehandle assembly18 as described above. It is also contemplated that either one or both of thejaw members80 and82 can be movable relative to one another in the same or similar manner as described above.First jaw member80 includes afirst flange81 which extends therefrom and acam slot86 located therethrough. Likewise,second jaw82 includes asecond flange83 which extends therefrom and acam slot88 located therethrough. Preferably, eachjaw80 and82 is formed from a stainless steel or some other electrically conductive material.
• The[0052]end effector assembly22 also includes anouter nose portion94 and aninner nose portion96 which engagejaw members82 and80, respectively. Afirst pivot105 is located onouter nose portion94 and is dimensioned to engage acorresponding pivot hole89 located onflange83. Asecond pivot103 is located oninner nose portion96 and is dimensioned to engage acorresponding pivot hole87 located onflange81. The center of rotation forfirst jaw member80 is about afirst pivot hole87 and the center of rotation forsecond jaw member82 is about asecond pivot hole89. Preferably, eachnose portion94 and96 is made from an electrically conductive material and transmits electrosurgical energy to arespective jaw member82 and80 as described in more detail below.
• As mentioned above with respect to FIG. 3, electrosurgical energy is transmitted from the electrosurgical generator to the[0053]PC board58 which transfers the energy into first and second poles. A pair ofterminal clips64aand64bare connected toPC board58 and transfer the first and second poles of alternating potential, respectively, to the different portions of thedrive rod assembly11, i.e., clip64aconnects toshaft12 and conducts the first pole tojaw member82 andclip64bconnects to ball contact38 which connects the second pole tojaw member80. Since both thedrive rod70 and theshaft12 are made from an electrically conductive material, aninsulation sleeve75 is disposed betweendrive rod70 andshaft12 to prevent theforceps10 from short circuiting.
• As best seen in FIG. 4, the[0054]inner nose portion96 is electrically connected withdrive rod70 and theouter nose portion94 is electrically connected toshaft12. The inner andouter nose portions96 and94capture yoke84 along withflanges83 and81.Yoke84 moves axially along axis “A” (see FIGS. 7 and 8) in a space between inner andouter portions96 and94 and aspacer stake119 maintains the separation of thenose portions96 and94 at their distal ends.Stake119 is dimensioned to engage and lock the inner andouter nose portions96 and94 together, which, in turn locksjaw member80 and82 atopyoke84. In some cases it may be preferable todimension stake119 such thatstake119 acts as a stop member and/or an additional stop member which controls the gap distance between the opposingjaw members80 and82 relative to one another. In this case,stake119 is formed from an electrically insulative material such as plastic. Thenose portions94 and96 provide lateral support for theflanges81 and83 and help ensure thatdetents90 and92 remain withincam slots86 and88, respectively.
• [0055]End effector assembly22 also includes aninner insulator102 and anouter insulator100 for maintaining electrical isolation between the first and second poles.Outer insulator100 insulatesouter nose portion94 frominner nose portion96 and driverod70 which conduct the second pole of electrical energy.Inner insulator102 insulatesinner nose portion96 fromouter nose portion94 andshaft12 which conduct the first pole of electrical energy. In this manner,outer nose portion94 can provide electrical continuity betweenshaft12 andjaw member82, whileinner nose portion96 can provide electrical continuity betweendrive rod70 andjaw member80.
• Preferably, a[0056]spring contact98 is utilized to maintain the electrical connection betweendrive rod70 andinner nose portion96 during axial motion of thedrive rod70. A donut-shapedspacer108 can also be utilized as a seal.Sleeve75 also acts as an insulation betweendrive rod70 andshaft12 and is envisioned to prevent accidental short circuiting of theforceps10 during movement of thedrive rod70.
• As mentioned above and as best seen in FIG. 4, drive[0057]rod assembly11 also includesgear52 which attaches toshaft12 and is designed to facilitate rotational movement of theend effector assembly22 about axis “A”. More particularly,gear52 includes anupper portion52aand a lower portion52bwhich each have a pair of outwardly extendingmechanical interfaces54aand54b, respectively, which are dimensioned to releasably engage a corresponding pair ofmechanical interfaces35 disposed onshaft12. Preferably,gear52 is made from an electrically insulative material such as, e.g., plastic, to avoid transferring electrosurgical energy to the rotatingassembly23. As best seen in FIG. 5A, rotatingassembly23 includes twohalf sections24aand24bwhich each include aflange77aand77b, respectively, which extends outwardly therefrom for engaginggear52. Rotation ofassembly23 effects rotational movement of theshaft12 which, in turn, rotates theend effector assembly22 about axis “A” (see FIGS. 9 and 10).
• Referring back to FIG. 4,[0058]yoke84 is preferably formed from an electrically insulative material such as plastic. Afirst side91 ofyoke84 facesfirst flange81 and asecond side93 ofyoke84 facessecond flange83. Whenyoke84 is positioned betweenflanges81 and83,yoke84 electrically insulates and isolates thefirst jaw member80 fromsecond jaw member82. In this manner, bipolar electrosurgical current can be conducted throughtissue150 which is grasped betweenjaws80 and82 withoutflanges81 and83 short circuiting.
• [0059]Yoke84 also includesfirst detent90 located on thefirst side91 which is dimensioned to movably engagecam slot86 and asecond detent92 located on thesecond side93 which is dimensioned to engagecam slot88. Preferably, the detent and cam slot combination,90,86 and92,88, respectively, work together as a cam-follower mechanical linkage. Linear motion ofdrive rod70 along axis “A” moves theyoke84 causingdetents90 and92 to slide within theirrespective cam slots86 and88. In one embodiment,slots86 and88 are angled with respect to the distal ends of thejaws80 and82 such that thejaws80 and82 move in a generally arcuate fashion toward and away from each other.
• In another embodiment, the inner periphery of the[0060]cam slots86 and88 are shaped to include two angles which, in turn, cause thejaw members80 and82 to move in two separate and distinct fashions relative to one another upon full extension of thedrive rod70. For example,cam slots86 and88 can include a first or proximal stage which effects generally arcuate movement of thejaw members80 and82 relative to one another and a second or distal stage wherein thejaw members80 and82 move in a more linear fashion relative to one another. It is envisioned that thecam slots86 and88 can be dimensioned to effect other movements of thejaw members80 and82 relative to one another depending upon a particular purpose, e.g., parabolic movement, cycloidal movement, and/or sinusoidal movement.
• As seen best with respect to FIGS. 7 and 8,[0061]detents90 and92 provide a force against the corresponding inner periphery ofcam slots86 and88 creating a moment aboutpivots103 and105, respectively. Preferably,cam slots86 and88 are arranged such that distal motion of thedrive rod70 causes thejaw members80 and82 to move together. Once thejaw members80 and82 are closed together, it is envisioned thatjaws80 and82 are held in clamped positioned by a continued compressive force on therod70 due to handlemember26. As mentioned above, thehandle assembly18 can include a lost motion mechanism for maintaining a predetermined or maximum clamping force for sealingtissue150 between thejaw members80 and82
• One of the advantages of the present disclosure is that excessive clamping forces which are normally associated with[0062]detents90 and92 are offloaded by the unique configuration ofyoke84 which prevents mechanical failure of theforceps10. More particularly, thecam slots86 and88 are preferably dimensioned such that the cam-follower motion of thedetents90 and92 withincam slots86 and88 simply operate to clamp thetissue150 between thejaw members80 and82 and a small moment arm is created between thedetents90 and92 and pivots103 and105, respectively. Before thedetents90 and92 reach their distal most positions within thecam slots86 and88, respectively, a pair ofshoulders111 and113 located on theyoke84 are dimensioned to engageflanges81 and83 and offload any additional clamping force applied by thehandle assembly18.
• In some cases it may be preferable to[0063]dimension cam slots86 and88 to have an enlarged distal end or cul-de-sac78aand78b, respectively, such that the cam-follower motion ofdetents90 and92 at their distal most point withinslots86 and88 will come to rest within the cul-de-sac78aand78ballowing the closure force to be offloaded byshoulders111 and113 abuttingflanges81 and83. It is envisioned that the cul-de-sacs78aand78bwhich are positioned withincam slots86 and88 will relieve shear stress on thedetents90 and92 approximately at the same time when theshoulder portions111 and113 of theyoke84 engage theflanges81 and83 to provide a closure force between thejaw members80 and82.
• The[0064]shoulders111 and113 abut the proximal end offlanges81 and83 to causejaw members80 and82 to close together with greater closure force. In other words,shoulder portions111 and113 provide a relatively large moment aboutpivots103 and105 to effect a high closure force between thejaw members80 and82. The unique configuration of the cam-follower linkage together with theshoulders111 and113 offloading high clamping forces preventdetents90 and92 from breaking due to mechanical failure. Since thepivots103 and105 are preferably made of metal and can withstand relatively high shear forces, theyoke84 and its component parts can be formed from an insulating material such as plastic without risk of mechanical failure due to the high clamping forces necessary to seal tissue. As mentioned above, forming theyoke84 from insulative materials will also prevent thejaw members80 and82 from shorting.
• A 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[0065]jaw members80 and82 and the gap between the opposingjaw members80 and82 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 twojaw members80 and82 would touch and possibly short resulting in little energy traveling through the tissue thus resulting in a bad seal. Too little force and the seal would be too thick.
• Applying 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.[0066]
• Preferably, the seal surfaces or[0067]tissue contacting surfaces151,251 (See FIGS.15B and16A-16G) of thejaw members80 and82 are relatively flat to avoid current concentrations at sharp edges and to avoid arcing between high points. In addition and due to the reaction force of thetissue150 when engaged,jaw members80 and82 are preferably manufactured to resist bending. For example and as best seen in FIGS. 2 and 16A-16G, thejaw members80 and82 are preferably tapered along width “W” 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 thejaw members80 and82 will resist bending due to the reaction force of thetissue150.
• As best seen in FIG. 4, in order to achieve a desired gap range (e.g., about 0.001 to about 0.005 inches and preferably about 0.002 inches to about 0.003 inches) and apply a desired force to seal the tissue, at least one[0068]jaw member80 and/or82 includes astop member139 which limits the movement of the two opposingjaw members80 and82 relative to one another. Preferably,stop member139 extends from the sealing surface or tissue contacting surface151 a predetermined distance according to the specific material properties (e.g., compressive strength, thermal expansion, etc.) to yield a consistent and accurate gap distance during sealing.
• As explained above, in some cases it may be preferable to[0069]dimension stake119 such that it acts like a stop member and/or an additional stop member and also controls/limits the movement of the two opposingjaw members80 and82 relative to one another. Preferably,stop member139 and/orstake119 is made from an insulative material, e.g., parylene, nylon and/or ceramic and is dimensioned to limit opposing movement of thejaw members80 and82 to within the above gap range.
• FIG. 11 shows the endoscopic[0070]bipolar forceps10 according to the present disclosure during use wherein movement of the handle assembly applies clamping force on thetubular tissue150 to effect aseal152 as shown in FIGS. 12 and 13. More particularly,shaft12 andend effector assembly22 are inserted through atrocar130 andcannula132 and handle26 is moved progressively towards fixedhandle28 to causejaw members80 and82 to grasptubular vessel150 therebetween. After thejaw members80 and82 are closed about thetissue150, the user then applies electrosurgical energy to thetissue150. By controlling the intensity, frequency and duration of the electrosurgical energy applied to thetissue150, the user can either cauterize, coagulate/desiccate, seal and/or simply reduce or slow bleeding. As shown in FIGS. 13 and 14, once the tubular vessel is sealed, thevessel150 can be cut alongseal152 to separate thetissue150 andform gap154 therebetween.
• FIGS. 15A and 15B shows an open vessel bipolar[0071]surgical forceps200 according to the present of disclosure. As can be appreciated,forceps200 also includes anend effector assembly222 which is attached to respective distal ends214aand214bof opposingelongated shafts212aand212b.End effector assembly222 includesjaw members280 and282 disposed atdistal ends214a,214b, respectively, which reside in opposing relation relative to one another and pivot aboutpivot219. Preferably, afinger ring232aand232bis attached to a correspondingproximal end216a,216bof eachshaft212a,212b, respectively, such that movement of the finger rings232a,232bimparts movement of thejaw members280,282 relative to one another from an open position (wherein thejaw members280 and282 are disposed in spaced relation relative to one another) to a clamping or closed position (whereinjaw members280 and282 cooperate to grasp tissue150 (FIG. 12) therebetween).
• FIG. 15B shows an enlarged view of one contemplated configuration of the[0072]jaw members280 and282 having astop member239 which is designed as a raised lip which extends along a the peripheral edge ofjaw member282 from aproximal end243 to adistal end245 of thejaw member282. It is envisioned thatforceps200 can also include any of the envisionedstop member239 configurations described below with respect to FIGS.16A-16G.
• FIGS.[0073]16A-16G show various contemplated configurations of thenon-conductive stop member139 disposed on, along or protruding through the bottom jaw member82 (282). It is envisioned that one ormore stop members139 can be positioned on either or bothjaw members80,82 (280,282) depending upon a particular purpose or to achieve a desired result. As can be appreciated by the present disclosure, the various configurations of thestop member139 are designed to both limit the movement of thetissue150 prior to and during activation and prevent short circuiting of thejaw members80,82 (280,282) as thetissue150 is being compressed.
• FIG. 16A shows[0074]stop member139 configured as a longitudinal ridge extending from aproximal end143 to adistal end145 ofjaw member82. FIG. 16B shows a series of stop members configured as longitudinally-oriented detents extending from theproximal end143 to thedistal end145 ofjaw member82. FIG. 16C shows a series of circle-like stop members139 extending from theproximal end143 to thedistal end145 ofjaw member82 in an alternating, laterally-offset manner relative to one another. It is envisioned that circle-like stop members139 are positioned proximate the right and left side edges147,149, respectively, ofjaw member82 and are substantially equal in size. However, it is envisioned that one or more of thestop members139 may be dimensioned or shaped differently than the other stop members depending upon a particular purpose or to achieve a desired result.
• FIG. 16D also shows a series of circle-[0075]like stop members139 extending from theproximal end143 to thedistal end145 of thejaw member82, however, each of thestop members139 is centrally disposed along width “W” of thejaw member82. FIG. 16E shows another configuration wherein thestop member139 is designed as a raised lip which projects from the outer periphery of thejaw member82.
• FIG. 16F shows yet another configuration which includes a stop member[0076]139bwhich is L-shaped and extends from theside edge147,149 of thejaw member82 in a catamaran-like fashion. Preferably acomplimentary stop member139ais disposed on thejaw member80 such that the twostop members139aand139babut one another when the jaws are moved towards the closed position. It is envisioned that configuring the jaw members in this fashion will provide lateral consistency and stabilization across width “W” (See FIG. 16D) of the overall gap distance (between about 0.001 inches to about 0.005 inches and preferably between about 0.002 and about 0.003 inches) between the sealingsurfaces151 of opposingjaw members80,82 (280,282). FIG. 16G shows yet another embodiment wherein thestop members139aand139bare generally C-shaped.
• Preferably, the non-conductive stop member(s)[0077]139 (239) is molded onto thejaw members80 and82 (e.g., overmolding, injection molding, etc.), stamped onto thejaw members80 and82 or deposited (e.g., deposition) onto thejaw members80 and82. For example, one technique involves thermally spraying a ceramic material onto the surface of thejaw member80 and82 to form the stop member(s)139. Several thermal spraying techniques are contemplated which involve depositing a broad range of heat resistant and insulative materials on the electrically conductive surfaces to createstop members139, e.g., High velocity Oxy-fuel deposition, plasma deposition, etc. Other techniques for disposing the stop member(s)139 on the electrically conductive surfaces are also contemplated, e.g., slide-on, snap-on, adhesives, molds, etc.
• It is envisioned that the stop member[0078]139 (239) protrudes about 0.001 to about 0.005 inches from the inner-facing surface of jaw member82 (282) which, as can be appreciated by the present disclosure, both reduces the possibility of short circuiting between electrodes and enhances the gripping characteristics of thejaw members80,82 (280,282). Preferably, thestop member139,239 protrudes about 0.002 inches to about 0.003 inches which has been determined to yield an ideal gap distance for producing effective, uniform and consistent tissue seals.
• Alternatively, the stop member[0079]139 (239) can be molded onto the Inner-facing surface of one or bothjaw members80,82 (280,282), or, in some cases, it may be preferable to adhere the stop member139 (239) to the inner facing surface of one or both of thejaw members80,82 by any known method of adhesion. Stamping is defined herein to encompass virtually any press operation known in the trade, including but not limited to: blanking, shearing, hot or cold forming, drawing, bending, and coining.
• FIGS.[0080]16A-16G show some of the possible configurations of thestop member139, however, these configurations are shown by way of example and should not be construed as limiting. Other configurations are also contemplated. For example, one or more of the configurations of FIGS.16A-16G may be combined to form a different stop member139 (239) configuration on the inner-facing surface of one or both of thejaw members80,82 (280,282). Although FIGS. 16C and 16D depict circle-like stop members139 (239) arranged in different configurations on or along jaw member82 (282), it is contemplated that other shapes may be equally effective in reducing the possibility of short circuiting between electrodes and enhancing tissue grip.
• Further, although it is preferable that the stop member[0081]139 (239) protrude about 0.001 inches to about 0.005 and preferably about 0.002 inches to about 0.003 inches from the inner-facing surface of the jaw member(s), in some cases it may be preferable to have the stop member139 (239) protrude more or less depending upon a particular purpose. For example, it is contemplated that the type of material used for thestop member139 and that material's ability to absorb the large compressive closure forces between jaw members while reducing the possibility of short circuiting between jaw members will vary and, therefore, the overall dimensions of thestop member139 may vary as well to produce the desired gap distance. In other words, the compressive strength of the material along with the desired or ultimate gap distance required (desirable) for effective sealing are parameters which are carefully considered when forming the stop members139 (239).
• As can be appreciated, one material may have to be dimensioned differently from another material to achieve the same gap distance or desired result. For example, the compressive strength of nylon is different from ceramic and, therefore, the nylon material may have to be dimensioned differently, e.g., thicker, to counteract the closing force of the opposing jaw members and to achieve the same desired gap distance.[0082]
• 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 present disclosure. For example, it may be preferable to add other features to the forceps[0083]10 (200), e.g., an articulating assembly to axially displace the end effector assembly22 (222) relative to the elongated shaft12 (212).
• Moreover, it is envisioned that the presently enclosed stop member configurations may also be incorporated onto a disposable and/or partially disposable electrosurgical instrument such as those described in commonly-assigned, pending U.S. application Ser. No. 09/425,696 filed on Oct. 22, 1999 entitled “OPEN VESSEL SEALING FORCEPS WITH DISPOSABLE ELECTRODES” by Tetzlaff et al., U.S. application Ser. No. 09/178,027 filed on Oct. 23, 1998 entitled “OPEN VESSEL SEALING FORCEPS WITH DISPOSABLE ELECTRODES” by Tetzlaff et al. and U.S. application Ser. No. 09/387,883 filed on Sep. 1, 1999 entitled “BIPOLAR ELECTROSURGICAL INSTRUMENT WITH REPLACEABLE ELECTRODES” by Schmaltz et al., the contents of all of which are hereby incorporated by reference in their entirety herein. More particularly, it is contemplated that the presently disclosed forceps may include a disposable electrode assembly which is selectively engageable with at least one portion of the electrosurgical instrument, e.g., end effectors, shaft(s) and/or handle(s).[0084]
• 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 exemplications of a preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.[0085]

Claims (15)

What is claimed is:

1. A bipolar forceps, comprising:

at least one elongated shaft having opposing jaw members at a distal end thereof, the jaw members being movable 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 cooperate to grasp tissue therebetween;

a source of electrical energy connected to each jaw member such that the jaw members are capable of conducting energy through tissue held therebetween; and

at least two non-conductive and spaced-apart stop members disposed on an inner facing surface of at least one of the jaw members which control the distance between the jaw members when tissue is held therebetween.

2. A bipolar forceps according toclaim 1 wherein the stop members are manufactured from the group consisting of: parylene, nylon and ceramic.

3. A bipolar forceps according toclaim 1 wherein the stop members include a series of longitudinally-oriented projections which extend from a proximal end of the jaw member to a distal end of the jaw member.

4. A bipolar forceps according toclaim 1 wherein the stop members include a series of circle-like tabs which extend from a proximal end of the jaw member to a distal end of the jaw member.

5. A bipolar forceps according toclaim 4 wherein the circle-like tabs are disposed in an alternating, laterally-offset manner relative to one another along a length of the jaw member.

6. A bipolar forceps according toclaim 4 wherein each of the circle-like tabs is centrally disposed along a width of the jaw member.

7. A bipolar forceps according toclaim 1 wherein the stop members protrude about 0.001 inches to about 0.005 inches from the inner facing surface of the jaw member.

8. A bipolar forceps according toclaim 1 wherein the stop members protrude about 0.002 inches to about 0.003 inches from the inner facing surface of the jaw member.

9. A bipolar forceps according toclaim 1 wherein the stop members are affixed to the jaw member by stamping.

10. A bipolar forceps according toclaim 1 wherein the stop members are affixed to the jaw member by thermal spraying.

11. A bipolar forceps according toclaim 1 wherein the stop members are affixed to the jaw member by an adhesive.

12. A bipolar forceps according toclaim 1 wherein the stop members are affixed to the jaw member by a molding process.

13. A bipolar forceps according toclaim 1 wherein the forceps includes a drive rod assembly which connects the jaw members to the source of electrical energy such that the first jaw member has a first electrical potential and the second jaw member has a second electrical potential; and

a handle attached to the drive rod assembly for imparting movement of the first and second jaw members from the first and second positions.

14. A bipolar forceps, comprising:

at least one elongated shaft having opposing jaw members at a distal end thereof, the jaw members being movable 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 cooperate to grasp tissue therebetween;

a source of electrical energy connected to each jaw member such that the jaw members are capable of conducting energy through tissue held therebetween; and

a stop member disposed along a periphery of an inner facing surface of at least one jaw member for controlling the distance between the jaw members when tissue is held therebetween.

15. A bipolar forceps, comprising:

at least one elongated shaft having opposing jaw members at a distal end thereof, the jaw members being movable 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 cooperate to grasp tissue therebetween;

a source of electrical energy connected to each jaw member such that the jaw members are capable of conducting energy through tissue held therebetween; and

a stop member which includes a longitudinally oriented ridge which extends from a proximal end to a distal end of an inner facing surface of at least one jaw member for controlling the distance between the jaw members.

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