Surgical instrument with eccentric cam

A forceps includes a housing, an elongated shaft assembly, and a cam assembly. The housing includes a movable handle pivotally coupled to the housing. The elongated shaft assembly is coupled to the housing and extends distally to support jaw members at a distal end thereof. One or both of the jaw members is selectively moveable relative to the other jaw member between a spaced apart position for manipulating tissue and a closed position for compressing tissue therebetween. The cam assembly is supported in the housing and includes an eccentric cam cable and an eccentric cam. The eccentric cam cable is operably coupled to the movable handle and positioned to rotate the eccentric cam upon movement thereof, wherein rotation of the eccentric cam reduces an amount of force on the movable handle required to move the jaw members to the closed position to compress tissue disposed between the jaw members.

TECHNICAL FIELD

This disclosure relates generally to the field of surgical instruments, and in particular, to surgical instruments such as endoscopic electrosurgical forceps that are economical to manufacture and use, for instance, to seal and cut tissue structures.

BACKGROUND

Instruments such as electrosurgical forceps are commonly used in open and endoscopic surgical procedures to coagulate, cauterize and seal tissue. Such forceps typically include a pair of jaw members that can be controlled by a surgeon to grasp targeted tissue, such as, e.g., a blood vessel. The jaw members may be approximated to apply a mechanical clamping force to the tissue, and are associated with at least one electrode to enable the delivery of electrosurgical energy to the tissue. The combination of the mechanical clamping force and the electrosurgical energy has been demonstrated to join adjacent layers of tissue captured between the jaw members. When the adjacent layers of tissue include the walls of a blood vessel, sealing the tissue may result in hemostasis, which may facilitate the transection of the sealed tissue. A detailed discussion of the use of an electrosurgical forceps may be found in U.S. Pat. No. 7,255,697 to Dycus et al.

A bipolar electrosurgical forceps typically includes opposed electrodes disposed on clamping faces or tissue engaging surfaces of the jaw members. The electrodes are charged to opposite electrical potentials such that an electrosurgical current may be selectively transferred through tissue grasped between the electrodes. To effectuate a proper seal, particularly in relatively large vessels, two mechanical parameters that should be controlled are the pressure applied to the vessel and the gap distance established between the electrodes.

Both the pressure and the gap distance influence the effectiveness of the resultant tissue seal. If an adequate gap distance is not maintained, there is a possibility that the opposed electrodes will contact one another, which may cause a short circuit and prevent energy from being transferred through the tissue. Also, if too low a force is applied, the tissue may have a tendency to move before an adequate seal can be generated. The gap distance between tissue engaging surfaces of a typical effective tissue seal is optimally between about 0.001 and about 0.010 inches. Below this range, the seal may shred or tear, and above this range, the vessel walls may not be effectively joined. Closure pressures for sealing large tissue structures typically fall within the range of about 3 kg/cm2to about 16 kg/cm2.

SUMMARY

According to one aspect, this disclosure is directed to a forceps including a housing, an elongated shaft assembly, and a cam assembly. The housing includes a movable handle pivotally coupled to the housing. The elongated shaft assembly is coupled to the housing and extends distally to support a pair of jaw members at a distal end thereof. One or both of the jaw members is selectively moveable relative to the other jaw member between a spaced apart position for manipulating tissue and a closed position for compressing tissue therebetween. The cam assembly is supported in the housing and includes an eccentric cam cable and an eccentric cam. The eccentric cam cable is operably coupled to the movable handle and positioned to rotate the eccentric cam upon movement thereof, wherein rotation of the eccentric cam reduces an amount of force on the movable handle required to move the jaw members to the closed position to compress tissue disposed between the jaw members.

In embodiments, the cam assembly may further include an annular cam positioned adjacent to the eccentric cam. The eccentric cam and the annular cam may be disposed on a shaft that is pivotally supported within the housing. The eccentric cam may include an inner eccentric cam plate and an outer eccentric cam plate that are configured to maintain the eccentric cam cable on an eccentric track defined between the inner and outer eccentric cam plates. The eccentric track may include an annular portion and a triangular portion. The annular portion and the triangular portion of the eccentric track may define a tear-dropped shaped profile.

In some embodiments, the annular cam may include an annular track defined therein including substantially the same diameter as the annular portion of the eccentric track.

In various embodiments, the forceps may further include an annular cam cable that is supported on the annular track of the annular cam. The elongated shaft assembly may extend into the housing and may support an inner shaft that operatively couples to the pair of jaw members. The inner shaft may support a collar that couples to the annular cam cable.

In embodiments, the forceps may further include a compression spring supported on the inner shaft. The compression spring may be engaged with the collar and an arm of the movable handle to spring bias the movable handle.

According to yet another aspect of this disclosure, an electrosurgical system includes a housing, an elongated shaft assembly, an annular cam, an eccentric cam. The housing includes a movable handle. The movable handle is coupled to the housing and pivotable between a distal position and a proximal position relative to the housing. The elongated shaft assembly is coupled to the housing and extends distally to an end effector. The end effector has a pair of jaw members movable between an open position and a closed position in response to movement of the movable handle between the distal and proximal positions. The annular cam is supported in the housing and coupled to the elongated shaft assembly. The eccentric cam is coupled to the annular cam and positioned to rotate with the eccentric cam as the movable handle pivots between the distal and proximal positions.

In embodiments, the elongated shaft assembly may include an inner shaft, wherein rotation of the annular cam may cause the inner shaft to axially translate between distal and proximal positions relative to the housing to actuate the pair of jaw members.

In some embodiments, the forceps may further include an annular cam cable coupled to the annular cam and a collar supported on the inner shaft. The inner shaft may support a compression spring engaged with the collar and the movable handle.

In various embodiments, the forceps may further include an eccentric cam cable coupled to the eccentric cam and to the movable handle.

In some embodiments, the annular cam and the eccentric cam may have different profiles. Rotation of the eccentric cam may change a jaw force ratio as the movable handle pivots relative to the eccentric cam.

In embodiments, the pair of jaw members may be configured to receive electrosurgical energy to selectively seal tissue disposed between the pair of jaw members.

In various embodiments, the forceps may further include a knife assembly that is actuatable to sever tissue disposed between the pair of jaw members.

According to yet another aspect of this disclosure, a forceps system includes a generator and a forceps. The forceps is coupled to the generator and includes a housing, a movable handle coupled to the housing, and an elongated shaft assembly that extends distally from the housing to a pair of jaw members at a distal end thereof. The pair of jaw members is disposed in electrical communication with the generator. The pair of jaw members is movable between a spaced apart position for manipulating tissue and a closed position for compressing tissue therebetween. The forceps further includes an eccentric cam coupled to the movable handle and positioned to rotate as the movable handle pivots between distal and proximal positions relative to the housing. Rotation of the eccentric cam relative to the movable handle reduces an amount of force on the movable handle required to move the pair of jaw members to a closed position to compress tissue disposed between the pair of jaw members.

Other aspects, features, and advantages will be apparent from the description, the drawings, and the claims that follow.

DETAILED DESCRIPTION

Embodiments of the disclosed electrosurgical forceps are described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views. As commonly known, the term “clinician” refers to a doctor, a nurse, or any other care provider and may include support personnel. Further, as is used in the art, the term “distal” refers to a position, a direction, and/or a structure, which is farther from the user, and the term “proximal” refers to a position, a direction, and/or a structure, which is closer to the user. In addition, directional terms such as upper, lower, front, rear, top, bottom, up, down, right, left, and the like are used simply for convenience of description and are not intended to limit this disclosure.

Referring initially toFIGS.1A-1C, an electrosurgical forceps100defines a longitudinal axis “X-X” and generally includes an instrument housing112, an elongated shaft assembly116that extends from instrument housing112, and an end effector114supported on a distal end of elongated shaft assembly116. Instrument housing112supports various actuators for remotely controlling end effector114through elongated shaft assembly116. Although this configuration is typically associated with instruments for use in laparoscopic or endoscopic surgical procedures, various aspects of this disclosure may be practiced in connection with endoluminal procedures and with traditional open instruments.

To mechanically control end effector114of electrosurgical forceps100, instrument housing112supports a stationary handle120, a movable handle122, a trigger126and a rotation knob assembly128. Movable handle122of instrument housing112is operable to move end effector114between an open position (FIGS.1A and1B) in which a pair of opposed jaw members130,132are disposed in spaced relation relative to one another, and a closed or clamping position (FIG.1C) in which jaw members130,132are closer together. Approximation of movable handle122toward stationary handle120, as indicated by arrow “A1,” serves to move end effector114to the closed position. Separation of movable handle122away from stationary handle120, as indicated by arrow “A2,” serves to move end effector114to the open position. Trigger126is operable to extend and retract a knife blade156(FIG.1B) through end effector114when end effector114is in the closed position (FIG.1C). Rotation knob assembly128serves to rotate elongated shaft assembly116and end effector114about longitudinal axis “X-X” of electrosurgical forceps100as rotation knob assembly128rotates about longitudinal axis “X-X,” as indicated by arrows “B.”

To electrically control end effector114of electrosurgical forceps100, stationary handle120of instrument housing112of forceps100supports a depressible button137that is operable by a clinician to selectively initiate and terminate delivery of electrosurgical energy to end effector114. Depressible button137is mechanically coupled to a switch136disposed within stationary handle120. Upon proximal movement of moveable handle122toward an actuated or proximal position, as illustrated by arrow “A1,” button137is configured to engage a button activation post138that extends from a proximal side of moveable handle122. Switch136is in electrical communication with an electrosurgical generator141via a cable143that extends from instrument housing112.

End effector114of electrosurgical forceps100may be moved from an open position (FIG.1B), in which tissue (not shown) can be received between jaw members130,132of end effector114, and a closed position (FIG.1C), in which tissue can be clamped and treated with electrosurgical energy delivered from generator141. Jaw members130,132pivot about a pivot pin144to move end effector114to the closed position (FIG.2B) in which sealing plates150,148of respective jaw members130,132provide a pressure to tissue grasped between jaw members130,132. In some embodiments, to provide an effective tissue seal, a pressure within a range between about 3 kg/cm2to about 16 kg/cm2and, typically, within a working range of about 7 kg/cm2to about 13 kg/cm2, may be applied by end effector114to the tissue. Also, in the closed position, a separation or gap distance is maintained between the sealing plates148,150by an array of stop members154(FIG.1B) disposed on or adjacent to sealing plates148,150. Stop members154contact opposing surfaces of jaw members130,132and prevent further approximation of sealing plates148,150. In some embodiments, to provide an effective tissue seal, an appropriate gap distance of about 0.001 inches to about 0.010 inches and, typically, between about 0.003 inches to about 0.006 inches, may be provided. In some embodiments, stop members154are constructed of a heat-resistant ceramic deposited onto jaw members130,132. In other embodiments, stop members154are constructed of an electrically non-conductive plastic molded onto jaw members130,132by a process such as overmolding or injection molding. Stop members154may be provided in any suitable number, arrangement, and/or configuration.

Upper and lower jaw members130,132of end effector114are electrically coupled to generator141to provide an electrical pathway to opposed tissue-engaging sealing plates148,150of lower and upper jaw members132,130, respectively. In some embodiments, sealing plates148and150are electrically coupled to opposite terminals, for example, positive or active (+) and negative or return (−) terminals associated with generator141so that bipolar energy may be provided through sealing plates148,150to tissue. Alternatively, sealing plates148,150may be configured to deliver monopolar energy to tissue. In a monopolar configuration, one or both sealing plates148,150deliver electrosurgical energy from an active terminal (+) while a return pad (not shown) is placed generally on a patient and provides a return path to the opposite terminal (−) of generator141.

Electrosurgical energy may be delivered to tissue through electrically conductive seal plates148,150to effectuate a tissue seal. Once a tissue seal is established, a knife blade156having a sharpened distal edge157may be advanced through a knife channel158defined in one or both jaw members130,132to transect sealed tissue. Although knife blade156is depicted inFIG.1Bas extending from elongated shaft assembly116when end effector114is in an open position, in some embodiments, extension of knife blade156into knife channel158when end effector114is in the open position is prevented.

For a more detailed description of a similar electrosurgical forceps, or components thereof, reference can be made, for example, to U.S. Pat. No. 9,655,673 to McCullough, Jr. et al. and U.S. Pat. No. 9,820,765 to Allen et al., the entire contents of each of which are incorporated herein by reference.

Referring now toFIGS.2,3A, and3B, instrument housing112further supports a cam assembly200that is pivotally coupled to instrument housing112. Cam assembly200, which may be formed (e.g., integrally) using any suitable manufacturing technique such as injection molding, welding, casting, machining, joining, additive printing, etc., or combinations thereof, includes a shaft202that supports an annular cam204and an eccentric cam206. In some embodiments, shaft202, annular cam204and eccentric cam206, may be monolithically formed.

Shaft202of cam assembly200includes opposite ends202a,202bthat extend from opposite sides of cam assembly200to pivotally couple cam assembly200to instrument housing112by any suitable mechanical coupling such as pin holes (not shown) defined in instrument housing112that receive opposite ends202a,202bof shaft202.

Annular cam204of cam assembly200includes an annular track204a, which may be supported concentrically about shaft202of cam assembly200. Annular track204ahas an annular profile (e.g., circular) with a diameter that can be greater than a diameter of shaft202. Annular cam204further includes a cable attachment portion204bthat secures a first end portion of annular cam cable208to annular cam204. Annular cam cable208is wound about annular track204a. Annular cam cable208extends from annular track204aand is redirected about any number of inner bars112x(e.g., three) extending from instrument housing112of forceps100at various locations along an inner surface of instrument housing112so that a second end portion of annular cam cable208couples to a collar116csupported on proximal end portion of elongated shaft assembly116of forceps100. Annular cam204also includes an outer cam plate204cpositioned adjacent to annular track204a. Outer cam plate204chas a diameter greater than a diameter of annular track204ato prevent annular cam cable208from sliding off annular track204a.

Eccentric cam206of cam assembly200includes an eccentric track206ahaving an eccentric profile (e.g., tear drop-shaped, pear-shaped, kite-shaped, egg-shaped, etc.). The eccentric profile of eccentric track206ais defined by an annular portion206bsupported (e.g., concentrically) about shaft202of cam assembly200and a triangular portion206c. Triangular portion206cextends from annular portion206bto an apex206d. Triangular and annular portions206b,206cof eccentric track206amay be coplanar. Eccentric track206ais supported between an inner eccentric cam plate206eand an outer eccentric cam plate206f. An eccentric cam cable210is configured to cam along eccentric track206a. Eccentric cam cable210is wound about eccentric track206aof eccentric cam206. Eccentric cable210extends from eccentric track206aand is redirected by any number of inner bars112xof instrument housing112(e.g., two). More particularly, a first end portion210aof cable210is secured to a cable attachment portion206gof eccentric cam206so that cable210can be wound about eccentric cam206. A second end portion210bof cable210extends from eccentric cam206and is secured to movable handle122. Eccentric track206ais recessed from inner and outer eccentric cam plates206e,206fso that inner and outer eccentric cam plates206e,206fprevent eccentric cam cable210from sliding off of eccentric track206aas eccentric cam cable210cams along eccentric track206aof eccentric cam206.

With reference toFIGS.3A and3B, a proximal end portion of elongated shaft assembly116supports a compression spring116a, a stop tab116band a collar116cwithin instrument housing112. Compression spring116ais supported between an arm122aof movable handle122and collar116cto urge movable handle122in a distal direction to bias end effector114(FIG.1) toward its open position. Arm122aof movable handle122is selectively engagable with stop tab116bto limit distal movement of moveable handle122as seen inFIG.3A.

In order to approximate jaw members130,132of end effector114, movable handle122is pivoted about pivot point “P,” as indicated by arrows “A1,” between a distal position (FIG.3A) in which end effector114is in an open position (FIG.1B), and a proximal position (FIG.3B) in which end effector114is in a closed position (FIG.1C). As movable handle122moves toward the proximal position, arm122aof movable handle122drives an inner shaft116dof elongated shaft assembly116, compression spring116a, and collar116cproximally, as indicated by arrow “C” to close jaw members130,132of end effector114. Inner shaft116dextends distally from instrument housing112and couples to end effector114to selectively move jaw members130,132between open and closed positions. Simultaneously, movable handle122tightens eccentric cam cable210, drawing second end portion210bof cable210proximally, as indicated by arrow “E,” while urging first end portion210aof cable210distally, as indicated by arrow “F,” so that cable210causes eccentric cam206to pivot downwardly and forwardly relative to instrument housing112toward movable handle122, as indicated by arrow “D.” Also simultaneously, cable208cams and wraps around annular cam204, namely, annular track204a, as indicated by arrows “G,” so that cable208facilitates movement of collar116cin the proximal direction relative to instrument housing112, as indicated by arrows “C.”

In this regard, cam assembly200functions to change a jaw force ratio as movable handle122moves between a distal position and a proximal position (and/or as end effector114/jaw members130,132move(s) from an open position to a closed position). The jaw force ratio is a ratio of an amount of force imparted to jaw members130,132over a predetermined increment of travel distance. Travel distance can be, for instance, an arc length of pivoting movement of moveable handle122as moveable handle122moves relative to instrument housing112. Alternatively and/or additionally, travel distance can be measured based on movement of jaw members130,132relative to one another. In one example, for each degree of pivoting movement of moveable handle122relative to instrument housing112through a first arc length, the amount of force imparted to jaw members130,132can be X, whereas for each degree of pivoting movement of moveable handle122through second arc length adjacent to the first arc length, the amount of force imparted to jaw members130,132can be 3×. More specifically, during initial movement of movable handle122toward a proximal position so that jaw members130,132approximate from an open position to a closed position, cam assembly200can provide a jaw force ratio of 1:1, as dictated by the similar diameters of annular cable track20aof annular cam204and annular portion206bof eccentric cable track206a. Further, when movable handle122moves through a predetermined arc length after jaw members130,132are closed, cam assembly200, namely eccentric cam206and cable210arrangement of cam assembly200, may impart a jaw force ratio of 3:1, for instance. In this regard, with the jaw force ratio of 3:1, a user requires less hand force to compress jaw members130,132together (see e.g.,FIGS.1CandFIG.3B) such as when sealing tissue disposed between jaw members130,132with electrosurgical energy transmitted to jaw members130,132.

After the user releases movable handle122, for example, when finished sealing tissue and/or cutting tissue between jaw members130,132, compression spring116aurges movable handle122toward the initial distal position (FIG.3A) where cam assembly200is in an unactuated position. In the unactuated position of cam assembly200, apex206dof eccentric cam206is pointed in a proximal direction (FIG.3A). By comparison, when movable handle122is in the proximal position (FIG.3B) and cam assembly200is in an actuated position (e.g., fully or substantially fully actuated), apex206dof eccentric cam206points in a downward direction (FIG.3B).

In embodiments, the profile of eccentric cam206can have any suitable shape and/or configuration with varying diameters along an outer surface thereof to provide a changing jaw force ratio, for example, when eccentric cam206rotates at the same rate as annular cam204. More particularly, the profile of eccentric cam206can be changed to achieve different movement and/or force ratios. Although annular cam204may be circular, in some embodiments, annular cam204may have any suitable shape and/or configuration, which may be the same and/or different from eccentric cam206in order to facilitate reduction in force required on the movable handle122.

In certain embodiments, annular cam cable208and eccentric cam cable210may be portions of a single unitary cable and/or sub-portions of a plurality of different cables. As can be appreciated, any of the disclosed cables can be one or more wires, fibers, threads, filaments, chains, belts, linkages, etc., or combinations thereof, and which may be braided, sheathed, coated, etc., and/or otherwise joined together using any suitable joining technique.

In some embodiments, cam assembly200may include any number and/or configuration of linkages to achieve a similar “eccentric” relationship as detailed above.

In certain embodiments, cables208,210and/or cams204,206can be provided in any suitable arrangement, for example, so that annular cam204is connected to moveable handle122(e.g., indirectly and/or directly) and eccentric cam206is connected to collar116c(e.g., indirectly and/or directly), or vice versa.

In some embodiments, compression spring116ais contained at least partially, or entirely, within collar116c.

In some embodiments, cam assembly200can include one or more pulleys in addition to, or in place of, one or more of cams204,206and/or cables208,210.

As can be appreciated, securement of any of the components of the presently disclosed apparatus can be effectuated using known securement techniques such welding, crimping, gluing, fastening, etc.

The various embodiments disclosed herein may also be configured to work with robotic surgical systems and what is commonly referred to as “Telesurgery.” Such systems employ various robotic elements to assist the clinician and allow remote operation (or partial remote operation) of surgical instrumentation. Various robotic arms, gears, cams, pulleys, electric and mechanical motors, etc. may be employed for this purpose and may be designed with a robotic surgical system to assist the clinician during the course of an operation or treatment. Such robotic systems may include remotely steerable systems, automatically flexible surgical systems, remotely flexible surgical systems, remotely articulating surgical systems, wireless surgical systems, modular or selectively configurable remotely operated surgical systems, etc.

The robotic surgical systems may be employed with one or more consoles that are next to the operating theater or located in a remote location. In this instance, one team of clinicians may prep the patient for surgery and configure the robotic surgical system with one or more of the instruments disclosed herein while another clinician (or group of clinicians) remotely controls the instruments via the robotic surgical system. As can be appreciated, a highly skilled clinician may perform multiple operations in multiple locations without leaving his/her remote console which can be both economically advantageous and a benefit to the patient or a series of patients. For a detailed description of exemplary medical work stations and/or components thereof, reference may be made to U.S. Pat. No. 8,828,023, and PCT Application Publication No. WO2016/025132, the entire contents of each of which are incorporated by reference herein.

Persons skilled in the art will understand that the structures and methods specifically described herein and illustrated in the accompanying figures are non-limiting exemplary embodiments, and that the description, disclosure, and figures should be construed merely as exemplary of particular embodiments. It is to be understood, therefore, that this disclosure is not limited to the precise embodiments described, and that various other changes and modifications may be effected by one skilled in the art without departing from the scope or spirit of this disclosure. Additionally, it is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of this disclosure, and that such modifications and variations are also intended to be included within the scope of this disclosure. Indeed, any combination of any of the disclosed elements and features is within the scope of this disclosure. Accordingly, the subject matter of this disclosure is not to be limited by what has been particularly shown and described.