Bifurcated shaft for surgical instrument

A surgical instrument includes a shaft having a proximal end and a bifurcated distal end defining a first shaft portion and a second shaft portion. An end effector assembly is disposed at the distal end of the shaft and includes first and second jaw members. One (or both) of the jaw members is moveable relative to the other between an open position and a closed position for grasping tissue therebetween. Each of the jaw members defines an opposed jaw surface and is independently coupled to one of the first and second shaft portions. The first and second shaft portions are configured to flex relative to one another during movement of the jaw members to the closed position to grasp tissue therebetween such that the opposed jaw surfaces of the jaw members are disposed in substantially parallel orientation relative to one another when grasping tissue therebetween.

BACKGROUND

1. Technical Field

The present disclosure relates to surgical instruments and, more particularly, to bifurcated shafts for use with surgical instruments.

2. Description of Related Art

Electrosurgical instruments (e.g., surgical forceps) are well known in the medical field, and typically include a handle, a shaft, and an end effector assembly that is operatively coupled to a distal portion of the shaft to manipulate tissue (e.g., grasp and seal tissue). Electrosurgical instruments utilize both mechanical clamping action and electrical energy to effect hemostasis by heating the tissue and blood vessels to coagulate, cauterize, seal, cut, desiccate, and/or fulgurate tissue.

As an alternative to open electrosurgical instruments for use with open surgical procedures, many modern surgeons use endoscopes and endoscopic electro surgical instruments (e.g., endoscopic forceps) for remotely accessing organs through smaller, puncture-like incisions. As a direct result thereof, patients tend to benefit from less scarring, fewer infections, shorter hospital stays, less pain, less restriction of activity, and reduced healing time. Typically, the endoscopic electrosurgical instrument is inserted into the patient through one or more various types of cannulas or access ports (typically having an opening that ranges from about five millimeters to about twelve millimeters) that has been made with a trocar.

Conventional electrosurgical instruments include a pair of jaw members that have a common pivot point (e.g., a pivot pin) disposed towards proximal ends thereof that facilitates manipulation of the jaw members between open and closed positions. In addition, the pivot point facilitates application of pressure by the jaw members to tissue grasped therebetween by preventing the opposed jaw surfaces from moving away from each other at the proximal ends of the jaw members. In this manner, when tissue is grasped between the opposing jaw members, a V-shaped configuration is defined therebetween since the distal ends of the jaw members are further away from each other than the proximal ends of the jaw members. When smaller-diametered tissue is grasped between the jaw members, the V-shaped configuration does not create any substantial problems, since the opposing jaw members are substantially parallel and relatively close to each other. However, when larger-diametered tissue is grasped between the jaw members, the opposing jaw surfaces are not substantially parallel to each other and further away from each other, thus inhibiting complete closure of the jaw members. More particularly, when larger-diametered tissue is grasped between the jaw members, the current density applied to tissue grasped therebetween during surgical treatment (e.g., fusion or ablation) tends to be substantially higher at the proximal end of the jaw members than towards the distal portion thereof, which creates uneven tissue fusion, or uneven ablation.

SUMMARY

In accordance with one embodiment of the present disclosure, a surgical instrument is provided. The surgical instrument includes a shaft having a proximal end and a bifurcated distal end defining a first shaft portion and a second shaft portion. An end effector assembly is disposed at the distal end of the shaft and includes first and second jaw members. One or both of the jaw members is moveable relative to the other between an open position and a closed position for grasping tissue therebetween. Each of the jaw members defines an opposed jaw surface. Further, each of the jaw members is independently coupled to one of the first and second shaft portions. The first and second shaft portions are configured to flex relative to one another during movement of the jaw members to the closed position to grasp tissue therebetween such that the opposed jaw surfaces of the jaw members are disposed in substantially parallel orientation relative to one another when grasping tissue therebetween.

In one embodiment, the opposed jaw surfaces define electrically conductive tissue sealing surfaces adapted to connect to a source of energy for sealing tissue grasped therebetween.

In another embodiment, the first and second shaft portions are configured to flex relative to one another to achieve a uniform closure pressure between the jaw members when grasping tissue therebetween. The closure pressure may be in the range of about 3 kg/cm2to about 16 kg/cm2during tissue sealing.

In still another embodiment, the first and second shaft portions are configured to flex relative to one another to achieve a uniform gap distance between the jaw members during tissue sealing.

In yet another embodiment, the shaft is bifurcated about a vertical axis thereof to define a first side shaft portion and a second side shaft portion. Alternatively, the shaft may be bifurcated about a horizontal axis thereof to define an upper shaft portion and a lower shaft portion.

In still yet another embodiment, each of the jaw members is independently coupled to one of the first and second shaft portions via a floating pivot.

In another embodiment, a cowling disposed about a portion of the bifurcated shaft and/or the jaw members. The cowling is configured to limit flexing of the first and second shaft portions relative to one another and/or may be disposed within a recess, or notch to retain the cowling in position about the bifurcated shaft and/or jaw members.

A surgical instrument provided in accordance with another embodiment of the present disclosure includes a shaft having a proximal end and a bifurcated distal end defining a first shaft portion and a second shaft portion. An end effector assembly is disposed at the distal end of the shaft and includes first and second jaw members, each defining an opposed jaw surface. The first jaw member is coupled to the first shaft portion via a first floating pivot and the second jaw member is coupled to the second shaft portion via a second floating pivot independent of the first floating pivot. The first and second jaw members are rotatable about the first and second floating pivots, respectively, relative to one another between an open position and a closed position for grasping tissue therebetween. The first and second floating pivots are moveable relative to one another as the jaw members are rotated to the closed position for grasping tissue therebetween such that the opposed jaw surfaces of the jaw members are disposed in substantially parallel orientation relative to one another when grasping tissue therebetween.

In one embodiment, the opposed jaw surfaces define electrically conductive tissue sealing surfaces adapted to connect to a source of energy for sealing tissue grasped therebetween.

In another embodiment, the first and second floating pivots are moveable relative to one another to achieve a uniform closure pressure between the jaw members during tissue sealing, e.g., between about 3 kg/cm2to about 16 kg/cm2.

In another embodiment, the first and second floating pivots are moveable relative to one another to achieve a uniform gap distance between the jaw members during tissue sealing.

In still another embodiment, the shaft is bifurcated about a vertical axis thereof to define a first side shaft portion and a second side shaft portion. Alternatively, the shaft may be bifurcated about a horizontal axis thereof to define an upper shaft portion and a lower shaft portion.

In yet another embodiment, the first and second shaft portions are configured to flex relative to one another to permit movement of the first and second floating pivots relative to one another.

In still yet another embodiment, a cowling is disposed about a portion of the bifurcated shaft and/or the jaw members to limit movement of the first and second floating pivots relative to one another. Further, the cowling may be disposed within a recess, or notch to retain the cowling in position about the bifurcated shaft and/or jaw members.

DETAILED DESCRIPTION

Embodiments of the presently-disclosed surgical instrument are described in detail with reference to the drawings wherein like reference numerals identify similar or identical elements. As used herein, the term “distal” refers to that portion of the instrument that is that is further from a user, while the term “proximal” refers to that portion of the instrument that is closer to a user.

In accordance with the present disclosure, an electrosurgical instrument is provided to include an end effector assembly having two opposing jaw members that are independently coupled to a shaft having a bifurcated configuration at a distal portion thereof. The bifurcated shaft includes two flexible half shafts that are configured to bend or flex away from each other when pressure is exerted therebetween. Each of the jaw members are pivotally coupled to the respective flexible half shaft at a respective floating pivot point such that each jaw member may independently move away from the other when grasping and sealing tissue therebetween. In this configuration, the flexible half shafts flex or bend away from each other to allow the jaw members to pivot towards a parallel configuration instead of a V-shaped configuration. A more detailed explanation of the novel bifurcated shaft having floating pivot points and various embodiments thereof is discussed in greater detail below.

Turning now toFIG. 1A, an embodiment of a surgical instrument10is shown for use with various surgical procedures and generally includes a housing20, a handle assembly22, a trigger assembly28, a switch30, a rotating assembly32, and an end effector assembly50having jaw members52and54that mutually cooperate to grasp, seal, and divide tubular vessels and vascular tissue.

Surgical instrument10also includes a shaft40that has a proximal portion40aand a vertically bifurcated distal portion40bthat mechanically engages end effector assembly50, as will be described in greater detail below. As schematically depicted inFIG. 1A, a longitudinal axis “Z-Z” is defined along shaft40, a horizontal axis “X-X” axis is defined in a transverse relation to longitudinal axis “Z-Z,” and a vertical axis “Y-Y” is defined in a perpendicular relation to both longitudinal axis “Z-Z” and horizontal axis “X-X.”

In some embodiments, electrosurgical instrument10may include an electrosurgical cable300that connects electrosurgical instrument10to a source of electrosurgical energy310(e.g., a generator). Cable300is internally divided into several cable leads (not explicitly shown) such that each transmits electrical potentials through their respective feed paths through electrosurgical instrument10to end effector assembly50. In other embodiments, electrosurgical instrument10may include an internal source of electrosurgical energy (not shown) that is disposed within housing20, for example, but not limited to a battery. In some embodiments, electrosurgical energy may be transmitted to sealing surfaces56,58(FIG. 3) of jaw members52,54, respectively, by switch30to treat tissue grasped therebetween. Switch30is disposed on housing20such that when jaw members52and54are in the closed configuration, a user may initiate the delivery of electrosurgical energy to jaw members52and54by conveniently manipulating switch30.

Still referring toFIG. 1A, handle assembly22includes a fixed handle24and a movable handle26that are configured to be manipulated by a user. Fixed handle24is integrally associated with housing20and handle26is movable relative to fixed handle24as explained in greater detail below with respect to the operation of surgical instrument10. Rotating assembly32is operatively connected to the housing20and is rotatable in either direction about longitudinal axis “Z-Z” to similarly rotate end effector assembly50about longitudinal axis “Z-Z.” More particularly, when rotating assembly32is rotated by a user in a clockwise or a counterclockwise direction, shaft40is similarly rotated which, in turn, rotates end effector assembly50in the respective clockwise or counterclockwise direction.

For a more detailed description of handle assembly22, rotating assembly32, and electrosurgical cable300(including line-feed configurations and/or connections) reference is made to commonly-owned U.S. Pat. No. 7,766,910 to Hixson et al. and U.S. Pat. No. 7,255,697 to Dycus et al.

As best shown inFIG. 2, in conjunction withFIG. 1A, shaft40includes proximal portion40aand bifurcated distal portion40b. Proximal portion40aof shaft40mechanically engages a distal portion of housing20and is received within housing20such that appropriate mechanical and electrical connections relating thereto are established. Vertically bifurcated distal portion40bof shaft40has a split-shaft configuration that includes a first half shaft42and a second half shaft44. First half shaft42and second half shaft44each include a respective vertical planar surface42aand44athat are substantially parallel to each other and along vertical axis “Y-Y.” Vertical planar surfaces42aand44aare separated from each other to define a space43therebetween.

First half shaft42and second half shaft44are joined together at a mid-portion40c(FIG. 1A) of shaft40. In some embodiments, shaft40includes a one-piece configuration from mid-portion40cto proximal portion40a. First half shaft42and second half shaft44are monolithically formed onto shaft40, or, alternatively, each of first half shaft42and second half shaft44may be separately attached at mid-portion40cof shaft40. In some embodiments, first half shaft42and second half shaft44have resilient or biasing characteristics to withstand and react to pressure exerted by jaw members52and54when grasping tissue therebetween and/or during tissue sealing, as will be described in greater detail below with respect to the operation of electrosurgical instrument10.

Referring now toFIGS. 1A and 3, end effector assembly50is pivotally attached to vertically bifurcated distal portion40bof shaft40. As discussed above, end effector assembly50includes a pair of jaw members52and54that are configured to pivot relative to each other. Movable handle26is operatively connected to shaft40that mechanically cooperates to impart movement of the jaw members52and54from an open position (FIG. 1A) wherein the jaw members52and54are disposed in spaced relation relative to each other, to a clamping or closed position (FIG. 3) wherein the jaw members52and54cooperate to grasp tissue therebetween.

Each jaw member52,54is independently coupled to distal portion40bof shaft40. More particularly, jaw member52is pivotally coupled to first half shaft42by a pivot pin46a(e.g., at a pivot point) and jaw member54is pivotally coupled to second half shaft44by a pivot pin46b(e.g., at a pivot point). Alternatively, jaw member52may be pivotally coupled to second half shaft44by a pivot pin46band jaw member54may be pivotally coupled to first half shaft42by a pivot pin46a. Pivot pins46aand46bhave a floating pin configuration. In this floating pin configuration, each jaw member52,54is pivotally coupled to respective flexible half shaft42,44by a respective floating pivot pin46a,46bsuch that each jaw member52,54may independently move away from the other, along vertical axis “Y-Y” (seeFIGS. 1A and 2) when tissue is grasped therebetween. In this manner, each flexible half shaft, namely first half shaft42and second half shaft44, flexes and/or bends to allow the respective jaw member52,54to pivot via the respective floating pivot pin46a,46btowards a parallel configuration, thus preventing the jaws from maintaining the V-configuration during the grasping and sealing of tissue therebetween. With this purpose in mind, first half shaft42and second half shaft44may be configured to maintain a predetermined pressure exerted by jaw members52and54during a sealing procedure.

Additionally or alternatively, first half shaft42and second half shaft44may be configured to apply and/or exert a predetermined threshold pressure towards jaw members52and54. In any of these scenarios, jaw members52and54are configured to pivot to a closed and substantially parallel configuration, in combination with the first half shaft42and second half shaft44, while maintaining the predetermined threshold pressure to properly effectuate a tissue seal.

In one embodiment, the combination of the mechanical advantage of the floating pin configuration along with the compressive force associated with vertically bifurcated distal portion40bof shaft40facilitates and assures consistent, uniform and accurate closure pressure about the tissue within the desired working pressure range (e.g., sealing threshold pressure) of about 3 kg/cm2to about 16 kg/cm2and, more specifically, about 7 kg/cm2to about 13 kg/cm2. By controlling the intensity, frequency and duration of the electrosurgical energy applied to the tissue, the user can effectively treat tissue (e.g., seal tissue).

In this manner, 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 members52and54and the gap distance “G” between opposing sealing surfaces56and58of jaw members52and54during the sealing process. However, the thickness of the resulting tissue seal cannot be adequately controlled by force alone. In other words, if too much force is exerted, jaw members52and54may touch and possibly create a short resulting in little energy traveling through the tissue, and thus resulting in a bad tissue seal. If too little force is exerted and the seal would be too thick.

Applying the correct force is important to oppose the walls of the vessel and to reduce the tissue impedance to a low enough value that allows enough current through the tissue. In other scenarios, the correct force is important to overcome the forces of expansion during tissue heating, to ensure adequate force is applied as tissue is “cooked down,” or contracted during the sealing process, in addition to contributing towards creating the required end tissue thickness, which is an indication of a proper seal. As such, the tissue impedance may be monitored during sealing to help ensure that an adequate tissue seal is formed.

In some embodiments, at least one jaw member, e.g.,54, may include one or more stop members (not explicitly shown) that limits the movement of the two opposing jaw members52and54relative to one another. The stop members (not explicitly shown) may extend from the sealing surface56,58of either of both of jaw members52,54, respectively, at a predetermined distance according to the specific material properties (e.g., compressive strength, thermal expansion, etc.) to define a minimum gap distance between jaw members52,54during tissue sealing. It is envisioned that the minimum gap distance between opposing sealing surfaces56and58of jaw members52,54during sealing ranges from about 0.001 inches to about 0.006 inches and, more specifically, between about 0.002 and about 0.005 inches, to inhibit shorting between the sealing surface56,58as tissue is “cooked down,” or contracted during the sealing process.

In some embodiments, as best shown inFIGS. 1A and 3, each jaw member52,54may include a cam slot (not explicitly shown) that corresponds to a respective cam slot47a,47bdefined on each of first half shaft42and second half shaft44. To facilitate movement of jaw members52and54, driving pins48aand48bare mechanically coupled to jaw members52and54, respectively, to allow opening and closing of jaw members52and54. Driving pins48aand48bindependently float with respect to each other and are mechanically coupled to handle assembly22(e.g., handle26) via a respective driving mechanism (not explicitly shown) to facilitate opening and closing of jaw members52and54. More specifically, upon depression of moveable handle26, the driving mechanism (not explicitly shown) urges drive pins48a,48bdistally along slots47a,47b, respectively, to move jaw members52,54towards the closed position, as shown inFIG. 3. On the other hand, when handle26is released, or moved back to its initial position, the driving mechanism (not explicitly shown) pulls drive pins48a,48bproximally along slots47a,47b, respectively, such that jaw members52,54are returned toward the open position.

As discussed above, jaw members52and54of end effector assembly50are pivotally coupled to respective first and second half shafts42and44, and are remotely operable by handle assembly22to open and close jaw members52and54. In particular, end effector assembly50may be configured as a bilateral assembly, e.g., where both jaw members52and54are moveable relative to one another, as shown inFIGS. 1A and 3, or may alternatively be configured as a unilateral assembly, e.g., where only one of jaw members52,54is moveable relative to the other, stationary jaw member52,54.

During movement of jaw members52and54from the open position to the closed position, jaw members52and54pivot toward each other and bifurcated shafts42,44may flex to allow pivot points46a,46bof jaw members52,54, respectively, to move away from each other. In this configuration, jaw members52and54can orient themselves in a substantially parallel configuration such that sealing surfaces56,58are substantially parallel to one another along the lengths thereof. This allows jaw members52,54to rotate about pivot pins46aand46b, while at the same time aligning themselves in parallel fashion. As discussed above, the floating pivot pin configuration allows pivot pins46a,46bto move away from each other to allow the jaw members to be parallel to each other. In this configuration, a threshold pressure and desired gap distance “G” between sealing surfaces56,58is readily achievable during tissue sealing, even if the size of tissue is altered during application of energy thereto, e.g., as a result of tissue contraction, or “cook-down.” Thus, by maintaining an accurate and consistent pressure and gap distance “G,” during application of electrosurgical energy to sealing surfaces56,58, throughout the sealing process, an effective tissue seal may be formed.

As discussed above, when jaw members52and54are approximated to the closed configuration and a threshold pressure is reached, first and second half shafts42and44are configured to “break” or discontinue application of closure pressure. In other words, the flexing, or bending of the shaft halves42,44limits the pressure applied to tissue grasped between jaw members52,54to a threshold pressure and ensures that the jaw members52and54are closed about tissue in a substantially parallel orientation relative to one another, thus ensuring a consistent and accurate gap “G” therebetween throughout the tissue sealing process. On the other hand, if tissue is contracted during the tissue sealing process, shaft halves42,44are flexed, or bent back to ensure that the desired closure pressure is maintained, i.e., such that the closure pressure does not fall too low.

Turning now to FIGS.1B and4-5, another embodiment of a surgical instrument100similar to surgical instrument10, is described. Surgical instrument100is similar to surgical instrument10described above with reference to FIGS.1A and2-3and, thus, will only be described generally, while focusing on the differences between surgical instrument100and surgical instrument10.

As shown in FIGS.1B and4-5, end effector assembly150includes a pair of opposing jaw members152and154each having an electrically conductive tissue sealing surface156and158, respectively. Jaw members152and154cooperate with each other to grasp tissue therebetween, as substantially described above with respect to the embodiment ofFIGS. 1A-3.

Surgical instrument100further includes a shaft140having a proximal portion140a, a mid-portion140c, and a bifurcated distal portion140b. Proximal portion140aof shaft140mechanically engages a distal portion of housing20and is received within housing20such that appropriate mechanical and electrical connections relating thereto are established. Bifurcated distal portion140bof shaft140is similar to bifurcated distal portion40bof shaft40(FIGS. 1A and 3), except that bifurcated distal portion140bof shaft140is split along a horizontal plane relative to horizontal axis “X-X” (rather than the vertically-bifurcated split of shaft40).

Horizontally bifurcated distal portion140bof shaft140has a split-shaft configuration that includes a first half shaft142and a second half shaft144. First half shaft142and second half shaft144are separated from each other to define a space143therebetween, as best shown inFIG. 4. First half shaft142and second half shaft144are joined together at mid-portion140cof shaft140. In some embodiments, shaft140includes a one-piece configuration from mid-portion140cto proximal portion140a. First half shaft142and second half shaft144are monolithically formed onto shaft140, or, in the alternative, each of first half shaft142and second half shaft144may be separately attached at mid-portion140cof shaft140. In some embodiments, first half shaft142and second half shaft144have resilient or biasing characteristics to withstand and react to pressure exerted by jaw members152and154when grasping and sealing tissue therebetween, as will be described in greater detail below with respect to the operation of surgical instrument100.

Referring now toFIGS. 1B and 5, end effector assembly150is pivotally attached to horizontally bifurcated distal portion140hof shaft140. As discussed above, end effector assembly150includes a pair of jaw members152and154that are configured to pivot relative to each other. Movable handle26is operatively connected to shaft140to impart movement of the jaw members152and154from an open position (FIG. 1B) wherein the jaw members152and154are disposed in spaced relation relative to each other, to a clamping or closed position (FIG. 5) wherein the jaw members152and154cooperate with each other to grasp tissue therebetween for sealing and other types of surgical treatments.

Each jaw member152,154is independently coupled to distal portion140bof shaft140. More particularly, jaw member152is pivotally coupled to first half shaft142by a floating pivot pin146aand jaw member154is pivotally coupled to second half shaft144by a floating pivot pin146b. Floating pivot pins146a,146bpermit jaw member152,154to independently move away from one another along horizontal axis “X-X” when tissue is grasped therebetween. In this manner, each flexible half shaft142,144flexes to allow the respective jaw member152,154to pivot via the respective floating pivot pin146a,146btowards a parallel configuration instead of maintaining the known V-configuration when grasping and sealing tissue therebetween

FIG. 5shows surgical instrument100grasping tissue between jaw members152,154. Once jaws members152and154are fully compressed about tissue, electrosurgical energy may be supplied to sealing surfaces156,158to seal tissue. The factors, parameters and additional features discussed above with respect to end effector assembly50(FIGS. 1A and 3) for adequately sealing tissue apply similarly to end effector assembly150and, thus, will not be repeated.

Referring generally toFIGS. 1A and 1B, in some embodiments, a suitable mechanical mechanism may be provided within bifurcated shafts40,140, to keep the bifurcated shaft halves42,44and142,144, respectively, in an initial position, e.g., wherein shaft halves42,44or142,144are substantially un-flexed or un-bent, for traditional operation of shafts40,140and end effector assemblies50,150, respectively, until a sufficient opposition force is present to flex, or bend the shafts halves42,44and142,144, respectively, to ensure substantially parallel closure of jaw members52,54and152,154, respectively.

For example, as shown inFIG. 6, jaw compression pressure (and the maintenance of the shaft halves in the initial position) may be facilitated by a cowling202(e.g., an elastic band). Cowling202may surround at least a portion of end effector assembly50and/or the bifurcated shaft (e.g., shaft40). More particularly, cowling202is disposed about pivot46a(FIG. 1) and pivot46b, coupling pivots46a,46bto one another to ensure adequate jaw compression pressure of jaw members52and54about tissue. Cowling202may be disposed within a notch or recess (not explicitly shown) defined within jaw members52,54to retain cowling202in position relative to jaw members52,54and/or to reduce the overall diameter of end effector assembly50. Further, a biasing member, (e.g., a spring) (not shown) may be utilized to provide added jaw compression pressure to end effector assemblies50,150, in addition to, or in place of cowling202.