Surgical instrument with variable tissue compression

Surgical instruments and methods for applying variable compression to tissue are described herein and can have particular utility when cutting and sealing tissue. In one embodiment, a surgical instrument end effector is described that includes first and second jaw members movable relative to one another between an open position and a closed position to clamp tissue therebetween. The end effector can include a compression member configured to translate along the end effector to move the first and second jaw members and apply a variable compression force to the tissue. The variable compression force can have different profiles along the length of the end effector, including, for example, a continuously increasing profile or a profile that alternates between different values. The provided variable compression can reduce the force required to actuate the surgical instrument and increase the quality of a tissue seal formed thereby.

FIELD

The present invention relates to surgical devices and, more particularly, to surgical devices for cutting and sealing tissue.

BACKGROUND

Surgical procedures often require the transection of tissue for a variety of purposes. In many cases, there is a need to both transect and seal tissue at the cutting site to prevent bleeding or fluid leakage from a luminal tissue structure being operated on. Accordingly, a number of devices exist for accomplishing these tasks, including devices configured for use in open surgery and minimally invasive procedures.

Many known devices include opposed jaw members configured to clamp tissue therebetween and a translating compression/cutting element that can drive the opposed jaw members to a closed position and also transect the tissue clamped between the jaw members. Sealing can likewise be accomplished in a variety of manners, including by the application of staples on either side of the compression/cutting element or the use of radio-frequency (RF) electrical or other energy to fuse the tissue together.

The opposed jaw members of some known devices may include one or more closure tracks that are configured to receive a portion of the compression/cutting element and guide the translation thereof along the jaw members. These closure tracks generally extend parallel to one another when the jaw members are in a closed position and are often arranged to provide for a desired gap between the jaw members when in the closed position.

There can be disadvantages to such devices, however. For example, a compression/cutting member can have a poor mechanical advantage when positioned close to a pivot joint of the jaw members, thereby requiring a large amount of force to compress tissue and advance along the jaw members. The poor mechanical advantage and large required force can make operation of the device difficult for users.

Additionally, in devices where RF or other energy delivery is used to seal tissue, forcing the actuation of the device can rush the procedure and transect the tissue before enough time has elapsed to sufficiently fuse the tissue. On the other hand, simply reducing the amount of compression provided in such devices can also be disadvantageous, because insufficient compression during sealing can lead to insufficient fusing of tissue. Insufficient sealing can cause bleeding from the transected tissue or leakage from a transected internal lumen or cavity.

Accordingly, there is a need for improved instruments and methods for applying variable compression to tissue to modulate required actuation forces during cutting and sealing operations. In particular, there is a need for improved instruments and methods that can reduce a required force to actuate an instrument while maintaining a desired level of compression and promoting effective sealing of tissue.

SUMMARY

The present invention generally provides surgical instruments and methods that employ variable tissue compression to address the shortcomings of the prior art. More particularly, the devices and methods described herein can modulate the compression force applied to tissue by an instrument to reduce a force required to actuate the instrument and allow for more effective sealing of tissue. In some embodiments, modulation can be accomplished by reducing an initial compression force applied to tissue and steadily increasing the compression force to a final value. In other embodiments, modulation can be accomplished by alternating between different compression levels (e.g., repeated alternation between higher and lower compression levels). Such variation in compression forces applied to tissue can be provided in a number of manners. In some embodiments, the instruments and methods of the present invention can include closure tracks extending along jaw members of an instrument that have variable profiles including sloped or curved portions. The various sloped or curved portions can allow a compression member to translate along the closure tracks with varying levels of resistance, thereby varying the force required to translate the compression member (i.e., the force required to actuate the device) and the compression force applied to the tissue through the jaw members.

In one aspect, a surgical end effector is provided that includes first and second jaw members movable relative to one another between an open position and a closed position to clamp tissue therebetween. The end effector also includes a first closure track formed in the first jaw member and extending along a length thereof, as well as a second closure track formed in the second jaw member and extending along a length thereof. The end effector further includes a compression member configured to translate longitudinally along a length of the end effector such that a first portion of the compression member contacts the first closure track and a second portion of the compression member contacts the second closure track to move the first jaw member and the second jaw member so as to apply compression to tissue disposed between the first and second jaw members as the compression member advances towards a distal end of the end effector. Still further, when the first and second jaw members are in the closed position, a distance between the first closure track and the second closure track increases continuously from a proximal-most end of the first closure track to a location adjacent to a distal end of the first closure track.

The devices and methods described herein can have a number of additional features and/or variations, all of which are within the scope of the present invention. For example, in some embodiments the distance between the first closure track and the second closure track can remain constant from the distal end of the first closure track to the location adjacent to the distal end of the first closure track. Such a feature can provide a flat region at the distal-most portion of the closure track to ensure that first and second jaws provide a desired level of compression to the tissue by the end of the compression member's translation. This feature can have particular utility in preventing distal tip bleeding or other tissue sealing complications from insufficient tissue compression.

In other embodiments, at least one of the first and second jaw members can include at least one electrode disposed on a surface thereof that is configured to contact tissue clamped between the first and second jaw members. In certain embodiments, for example, a single electrode can be disposed on either one of the first and second jaw members, while in other embodiments a plurality of electrodes can be disposed on both the first and second jaw members. In other embodiments, however, other sealing mechanisms can be employed, such as stapling cartridges, etc.

The first and second closure tracks of the end effector can have a variety of shapes. For example, in some embodiments the distance between the first closure track and the second closure track can increase linearly from the proximal-most end of the first closure track to the location adjacent to the distal end of the first closure track. In other words, the distance between the first and second closure tracks can increase continuously from a proximal-most end of the closure tracks to, for example, a point adjacent to a distal end of the closure tracks where a flat region can begin. In other embodiments, however, the distance can continuously increase from the proximal-most end to the distal end of the closure tracks. In still other embodiments, a profile of the distance between the first closure track and the second closure track between the proximal end of the first closure track and the location adjacent to the distal end of the first closure track can be curved or waveform-like.

The second closure track can also have a variety of shapes and profiles, depending on the particular embodiment. For example, a distance between the second closure track and a surface of the second jaw member that faces the first jaw member can remain constant from a proximal-most end of the second closure track to a distal end of the second closure track. Such an embodiment can be utilized, for example, if the second jaw member is fixed and the first jaw member moves relative thereto. The second closure track need not have such a flat profile, however, and in some embodiments a distance between the second closure track and a surface of the second jaw member that faces the first jaw member can vary from a proximal-most end of the second closure track to a distal end of the second closure track. A number of different track shapes or profiles are possible, similar to the first closure track described above. For example, in some embodiments a profile of the distance between the second closure track and the surface of the second jaw member can include at least one sloped or curved portion.

In another aspect, a surgical end effector is provided that includes first and second jaw members movable relative to one another between an open position and a closed position to clamp tissue therebetween. The end effector further includes a first closure track formed in the first jaw member and extending along a length thereof, as well as a second closure track formed in the second jaw member and extending along a length thereof. The end effector also includes a compression member configured to translate longitudinally along a length of the end effector such that a first portion of the compression member contacts the first closure track and a second portion of the compression member contacts the second closure track. Still further, a profile of at least one of the first closure track and the second closure track can be a wave function to vary an amount of compression applied to the tissue clamped between the first and second jaw members.

The wave function profile of the first and/or second closure track can have a variety of forms. For example, in some embodiments the profile of at least one of the first closure track and the second closure track can be a wave function having constant amplitude and frequency. In such an embodiment, a distance between the first closure track and the second closure track when the first and second jaw members are in the closed position can repeatedly and regularly alternate between a first distance and a second distance along a length of the end effector to vary an amount of compression applied to the tissue clamped between the first and second jaw members. Expressed another way, a profile of the distance between the first closure track and the second closure track can match a sinusoidal wave function, wherein a wavelength and amplitude is constant over a length of the first closure track.

In other embodiments, the profile of at least one of the first closure track and the second closure track can be a wave function having at least one of variable amplitude and variable frequency. In such embodiments, the distance between the first closure track and the second closure track when the first and second jaw members are in the closed position can alternate (regularly or irregularly) between a first distance and at least a second distance along a length of the end effector. In still other embodiments, the profile of at least one of the first closure track and the second closure track can be a wave function having both variable amplitude and variable frequency. By way of further example, in one embodiment the distance between the first closure track and the second closure track can alternate between a first distance, a second distance, and a third distance along the length of the end effector.

By varying the frequency and/or amplitude of the wave function defined by the closure track profile of the first jaw member and/or second jaw member, the distance between the jaw members can be varied along the length of the end effector. In some embodiments, for example, the second distance can be greater than the first distance, or vice versa. Further, if there is a third distance, as in the example above, the third distance can be greater than the second distance and the first distance in certain embodiments. Regardless, the variation in compression (e.g., alternation between higher and lower levels of compression) can modulate the amount of force required to actuate the end effector and, in certain embodiments, can promote better fusing of tissue during application of RF or other energy. In addition, in certain embodiments the end effector can be part of a larger surgical instrument, and can include a shaft extending proximally from the end effector, as well as a handle coupled to a proximal end of the shaft. The handle can include a trigger mechanism to cause the compression member to be translated along the end effector, deliver RF or other energy to seal tissue, etc.

In certain embodiments, the first closure track can include a flat distal-most portion that is traversed by the compression member after the alternations, similar to the flat portion described above. For example, the distance between the first closure track and the second closure track can remain constant from a distal end of the first closure track to a location adjacent to the distal end the first closure track.

As noted above, the regular or irregular alternation or oscillation between different distance values can be accomplished by varying the profiles of any of the first closure track and the second closure track. And any of the variations or modifications to the first and/or second closure track described herein can be applied in any combination to either closure track.

In another aspect, a method for actuating a surgical instrument is provided that includes positioning an end effector having first and second jaw members such that tissue is disposed within a gap between the first and second jaw members, and applying a continuously variable compression force to the tissue by advancing a compression member distally along a length of the end effector.

The method can also include a number of additional steps or variations, all of which are considered within the scope of the present invention. For example, in some embodiments the method can further include applying a constant compression force to the tissue as the compression member is advanced over a distal-most portion of the end effector. By way of further example, such a constant compression force can be provided by advancing the compression member over a distal-most flat portion (e.g., a portion parallel to a lower surface of the jaw member or a closure track of the opposing jaw member) of closure track, as described above.

In other embodiments, the continuously variable compression force applied to the tissue can continuously increase as the compression member is advanced distally along the length of the end effector. In certain other embodiments, however, the continuously variable compression force applied to the tissue can repeatedly alternate between a first value and a second value that is higher than the first value as the compression member is advanced distally along the length of the end effector. Any of the various modifications to a continuously increasing or repeatedly alternating compression force described above can be employed as well.

In still other embodiments, the method can further include delivering energy into the tissue from at least one electrode coupled to the end effector to seal the tissue. For example, at least one of the first and second jaw members can include at least one electrode coupled thereto that can be utilized to deliver energy into tissue clamped between the jaw members. In other embodiments, however, the method can also include delivering alternative sealing mechanisms into tissue, such as staples, etc.

As noted above, any of the additional features or variations described above can be applied to any particular aspect or embodiment of the invention in a number of different combinations; the absence of explicit recitation of any particular combination is due solely to the avoidance of repetition in this summary.

DETAILED DESCRIPTION

The present invention is generally directed to surgical devices and methods that are used in tissue cutting and sealing operations. The devices and methods described herein employ variable tissue compression during actuation to reduce the force required to actuate a surgical device and promote more effective sealing of tissue. In general, reducing the amount of compression provided when the device has a lower mechanical advantage over the tissue and increasing the amount of compression as the device's mechanical advantage increases can reduce the force required to actuate a surgical device. In other embodiments, however, the amount of compression can be repeatedly modulated between higher and lower values to both reduce the force required to actuate and to promote the formation of an effective tissue seal when applying RF energy.

FIG. 1shows one embodiment of a surgical instrument100that can be used to cut and seal tissue. The surgical instrument100can generally include a handle portion2, a shaft4, and an end effector6. Manipulation of components of the handle portion2can be effective to manipulate the shaft4and/or the end effector6during an open or minimally invasive surgical procedure.

While a person having skill in the art will recognize that the size, shape, and configuration of each of the handle portion2, shaft4, and end effector6can depend, at least in part, on the size, shape, and configuration of the components used therewith and the type of procedure being performed, in the illustrated embodiment the handle portion2is of a pistol-grip nature and includes a first trigger14pivotally coupled to the handle portion2. Pivotal movement of the trigger14towards the handle portion2can be effective to actuate the end effector6, and thus as shown is effective to move jaws24a,24bof the end effector6from an open position (FIG. 2) to a closed position (FIG. 3). More particularly, movement of the trigger14can initiate one or more mechanical and/or electrical signals or processes that cause the actuation of the end effector6. A person skilled in the art will recognize a variety of different mechanical and electrical components that can be associated with either or both of the handle portion2and the shaft4to assist in actuating the end effector6. Further, in addition to being able to have a variety of sizes, shapes, and configurations, the handle portion2can also be made from a variety of materials. In one embodiment, for example, the handle portion2can be made from a generally rigid material such as a metal (e.g., stainless steel, titanium, etc.) or a rigid polymer.

In some embodiments the handle portion2can include a rotational control collar16that can be used to rotate the shaft4and/or the end effector6. As shown, the collar16can be rotated about a longitudinal axis A, which in turn can rotate each of the shaft4and the end effector6a full 360 degrees about the longitudinal axis A, as shown by arrow17. The first and second jaws24a,24bcan remain operable to open and close while being rotated.

Further, in some embodiments a proximal end of the handle portion2can be coupled to a radio frequency (RF) or other energy source8and a controller10via a cable12. The RF energy from the source8can be delivered through the handle to the end effector6for use in sealing tissue. An activation button20can be provided to initiate, for instance by completing a circuit, and/or otherwise control the application of RF energy to the instrument and thus tissue disposed in the jaws24a,24b. Alternatively, any combination of one or more activation buttons, the trigger14, a foot pedal, and/or other known control devices can be used to initiate, apply, and/or otherwise control RF energy supplied for sealing tissue. In embodiments that do not use RF energy to seal tissue, the handle portion2can include other mechanical or electrical structures known to those skilled in the art to deliver other forms of tissue sealing, such as staples.

A person skilled in the art will recognize other non-limiting examples of features that can be incorporated with the handle portion2to assist in manipulating or otherwise operating the device include: (1) an articulation lever for articulating the end effector6; (2) a retraction handle for retracting a cutting blade or compression member, such as the compression member22described further below, towards and/or to their initial positions in place of or independent of any retraction that is part of a firing stroke initiated by the trigger2; (3) a firing lockout assembly to prevent a cutting blade or compression member from being actuated at an undesirable time; and (4) an emergency return button to retract a cutting blade or compression member before a firing stroke is completed, for instance in a case where completing the firing stroke may cause tissue to be undesirably cut. Although features such as an articulation lever, a retraction handle, a firing lockout assembly, and an emergency return button are not explicitly illustrated in the device100, a person skilled in the art will recognize a variety of configurations for each feature that can be incorporated into the handle portion2and/or other portions of the device100without departing from the spirit of the present disclosure.

The shaft4can be removably coupled to the distal end of the handle portion2at a proximal end of the shaft4and can include an inner lumen extending therethrough for passing mechanisms to help actuate the jaws24a,24b, or to perform other functions at the surgical site, such as cutting or delivering electrical energy for sealing. By way of non-limiting examples, components such as an actuation rod, a cutting blade or compression member, leads, and other mechanical and/or electrical control can be associated with portions of the handle portion2, extend through the inner lumen of the shaft4and to the end effector6to assist in the operation of the device100generally and the end effector6more specifically.

A distal end of the shaft4can be configured to receive the end effector6by any known means for coupling an end effector to a shaft, including by a removable connection that allows various end effectors to be removably and replaceably coupled to the distal end of the shaft4. While the shaft4can have any number of shapes and configurations, depending, at least in part, on the configurations of the other device components with which it is used and the type of procedure in which the device is used, in the illustrated embodiment the shaft4is generally cylindrical and elongate.

In some embodiments, the shaft4can be formed from a rigid material, e.g., a metal such as stainless steel, titanium, etc., or a rigid polymer, while in other embodiments the shaft4can be formed from semi-rigid or flexible materials to allow for deformation when desired, such as during some types of minimally invasive procedure. Exemplary semi-rigid materials can include polypropylene, polyethylene, nylon, or any of a variety of other known materials. The shaft4can have any longitudinal length, although in some embodiments it can be long enough to allow the handle portion2to be manipulated outside a patient's body while the shaft4extends through an opening in the body to position the end effector6at a surgical site within the patient's body. The shaft4can similarly have any diameter but, in some embodiments, can have a diameter suited to introduction into a patient's body during a minimally invasive surgery.

FIGS. 2 and 3illustrate one, non-limiting embodiment of an end effector6that can be coupled to a distal end of the shaft4. As shown the end effector6can include first and second jaw members24a,24bthat are movable relative to one another between an open position, as shown inFIG. 2, and a closed position, as shown inFIG. 3, to clamp tissue disposed within a gap21therebetween. The first and second jaw members24a,24bcan extend distally from a proximal end of the end effector and can be pivotably attached or otherwise coupled to one another. In some embodiments, one jaw member can be fixed while the other is configured to pivot, for instance the second jaw member24bcan be fixed relative to the end effector6, such that closure of the end effector is accomplished by movement of the first jaw member24aalone. In other embodiments, however, both the first and second jaw members24a,24bcan be configured to pivot independently. Further, in some embodiments each jaw member24a,24bcan include teeth26or other surface features (e.g., a textured or roughened surface) formed thereon to more effectively grip tissue when the jaw members are in the closed position. The end effector6, and thus the jaws24a,24band related components, can have a variety of sizes, shapes, and configurations, depending, at least in part, on the size, shape, and configuration of the components used therewith and the type of procedure being performed. In some embodiments, the end effector6can be sized such that the proximal end of the end effector can be telescopically received within the shaft during the operation, or the entire end effector6can be sized to be received within a trocar or other sleeve during introduction into a patient's body.

FIG. 2illustrates the end effector6in an open position wherein the end effector can be positioned such that tissue is disposed between the first and second jaw members24a,24b. The first jaw member24acan, in some embodiments, include a first energy delivery surface28a(not visible) including at least one electrode. The second jaw member24bcan similarly include a second energy delivery surface28bincluding at least one electrode. The first and second energy delivery surfaces28a,28bcan have a variety of configurations. In one embodiment, the energy delivery surfaces28a,28bcan extend in a “U” shape about the distal end of end effector6, as shown inFIG. 2with respect to the energy delivery surface28b. The energy delivery surfaces28a,28bcan provide a tissue contacting surface or surfaces for contacting, gripping, and/or manipulating tissue therebetween. As discussed above, the end effector6can be coupled to an RF energy source8via the shaft4and handle portion2. In the illustrated embodiment, a user of the device100can press the activation button20which would signal the controller10to deliver RF energy to the energy delivery surfaces28a,28b, thereby sealing the tissue captured between the first and second jaw member24a,24b. While in the illustrated embodiment each jaw24a,24bis described as having an energy delivery surface28a,28b, in other embodiments only one jaw may have an energy delivery surface, or if the device is not configured to include energy delivery, neither jaw can have an energy delivery surface in some instances.

As just indicated, in some embodiments it may not be desirable to use RF energy to seal tissue, and thus energy delivery surfaces can not be included in some embodiments. A person skilled in the art will recognize that alternative tissue sealing mechanisms can be employed in conjunction with the disclosures provided for herein. By way of non-limiting example, in some embodiments, features such as an anvil and staple cartridge can be incorporated into the jaw members24a,24bto allow stapling to be performed by the end effector. In such an embodiment, the end effector6can contain a plurality of staples, which, upon the closure of the first and second jaw members24a,24b, can be delivered into tissue grasped between the jaw members. One or more rows and/or columns of staples can fired into tissue disposed between the jaw members24a,24b, as is known to those skilled in the art. More particularly, a first jaw member can include a plurality of staple forming pockets formed as part of an anvil and a second jaw member can include a plurality of staples held in a cartridge. Upon actuation, the staples can be ejected from the cartridge through the tissue disposed between the first and second jaw members. The staples can then abut against the staple-forming pockets in the second jaw member, which can close the staples and complete the tissue seal. U.S. Patent Publication No. 2004/0232197 to Shelton et al., which is hereby incorporated by reference in its entirety, provides some exemplary disclosures pertaining to end effectors that perform stapling and that can be used in conjunction with the disclosures provided for herein.

Movement of the first and second jaw members24a,24bbetween the closed and open positions described above can, in some embodiments, be controlled by a translating compression member22. In the illustrated embodiment ofFIGS. 1-3, the compression member22rides within a compression member cavity30that extends along the length of the first and second jaw members24a,24b. Extending the compression member22from a proximal end of the end effector6towards a distal end thereof can cause the first and second jaw members24a,24bto pivot toward one another, thereby applying a compression force to tissue disposed in the gap21therebetween. As is described in more detail below, continued distal translation of the compression member22can apply additional compressive force to the tissue disposed between the jaw members24a,24b. In some embodiments, the compression member can include a cutting blade formed on or otherwise located on a distal, leading end thereof such that translation of the compression member towards the distal end of the jaw members24a,24bcan transect tissue disposed between the jaw members24a,24b. The transected tissue can subsequently be sealed using techniques described herein or otherwise known to those skilled in the art.

In other embodiments, a separate closure mechanism can be employed to move the first and second jaw members24a,24bbetween the open and closed positions, however, and the translating compression member can be actuated only after the jaw members have been brought to a substantially closed position by the separate closure mechanism. For example, U.S. patent application Ser. No. 14/075,839, filed Nov. 8, 2013, and entitled “Electrosurgical Devices,” discloses an independent closure mechanism for moving jaw members from an open to a substantially closed position. The entire contents of this application are hereby incorporated by reference herein.

Returning to the compression member cavity30, both the first and second jaw members24a,24bcan include such a cavity that is sized to receive a compression member22when the compression member22is extended distally.FIGS. 2 and 3illustrate one exemplary embodiment of a compression member22. The compression member cavity30can extend along a length of each of the first and second jaw members24a,24bat a medial location to direct the compression member22as it is advanced from a proximal end to a distal end of the first and second jaw members. The compression member22can be guided by at least one closure track32a,32bdefined in the sidewalls of the compression member cavity of each jaw member24a,24b. As the compression member22is actuated to translate along the longitudinal axis A of the end effector6through the channel30, the first jaw member24acan be pivoted downward towards the closed position as shown inFIG. 3, thereby applying a compression force to tissue disposed between the first and second jaw members. In addition, a leading edge of the compression member22can cut through the tissue, transecting it.

Movement of the compression member22can be controlled by the first trigger14of the handle portion2. For example, as the trigger14is moved toward the body of the handle portion2, the compression member22can be advanced distally from an initial proximal location of the end effector6towards a distal end of the end effector6. As the compression member22traverses the end effector, a first portion of the compression member22can engage with a first closure track32aformed on the first jaw member24aand a second portion of the compression member22can engage with a second closure track32blocated in the second jaw member24b. The portions of the compression member22that engage the closure tracks32a,32bcan transfer forces from the distal advancement of the compression member22into compression forces acting on tissue grasped between the two jaw members24a,24b.

As shown inFIGS. 2 and 3, the compression member22can, in some embodiments, have an I-beam cross-sectional shape beam that extends along the entire length of the compression member22. Such a compression member22can include a first flat section22awhich can be received in to the first closure track32aof the first jaw member24a. The first flat section22acan have a perpendicular section22bcoupled thereto and extending toward the second jaw member24b. An opposing end of the perpendicular section22bcan be coupled to a second flat section shown) which mirrors the first flat section22aand is received within the second closure track32bof the second jaw member24b.

FIG. 5illustrates another embodiment of a compression member122. The compression member122includes an I-beam cross-sectional shape only along a distal portion thereof. The upper portion of the distal end can have an upper left-side flange122aand an upper right-side flange122bthat do not extend axially along the entire length of the compression member122. The lower portion of the distal end can include a lower left side flange122cand a lower right side flange122dthat similarly do not extend axially along the entire length of the compression member122. The upper left and right side flanges122a,122bof the compression member122can be received within parallel closure tracks formed in a first jaw member, while the lower left and right side flanges122c,122dcan be received within closure tracks formed in a second jaw member. As the compression member122is advanced through an end effector from a proximal end to a distal end thereof, a distance between the closure tracks in the first and second jaw members can be varied from a large distance to a relatively smaller distance in accordance with the disclosures provided for herein. The fact that the side flanges do not extend along the entire length of the compression member122can allow for the application of variable tissue compression by altering the profile of the closure tracks that the flanges ride within the tracks, as described in more detail below.

Compression members used in combination with the devices and methods of the present invention are not limited to the above-described I-beam shape.FIG. 6, for example, illustrates an alternative embodiment of a compression member222having a “C” cross-sectional shape that extends along at least a distal portion of its length. The upper portion of the distal end has a first side flange222athat does not extend along the entire length of the compression member. The lower portion of the distal end similarly includes a second side flange222bthat can be on the same side as the first side flange222aand can extend along the compression member for a similar distance as the first side flange222a. The first side flange222aof the compression member222can be received within a first closure track of a first jaw member and the second side flange222bcan be received within a second closure track of a second jaw member. As the compression member222is advanced along the first and second jaw members from a proximal end to a distal end thereof, a distance between the closure tracks in the first and second jaw can be varied from a large distance to a relatively smaller distance in accordance with the disclosures provided for herein. Similar to the embodiment ofFIG. 5, the fact that the side flanges do not extend along the entire length of the compression member222can allow for the application of variable tissue compression by altering the profile of the closure tracks that the flanges ride within the tracks, as described in more detail below.

In still another exemplary embodiment illustrated inFIG. 7, a compression member322can have one or more pins322aand322bin place of flanges. Depending on the profile of the closure tracks utilized, the pins322aand322bcan provide a smoother ride (i.e., lower levels of friction, which can further reduce the force required to actuate the device) along the closure track. Furthermore, in some embodiments the pins322aand322bcan be configured to rotate and operate as wheels running over the closure tracks of the first and second jaw members. The pins332a,332bcan extend in a single direction from a surface322sof the compression member322as shown, or alternatively, the pins332a,332bcan also extend in the opposed direction from an opposed surface (not shown) of the compression member322, thereby providing a configuration more akin to the I-beam shaped cross-section described above.

FIG. 7also illustrates a compression member322that includes a cutting blade44disposed at a distal end thereof. The cutting blade44can have a sharp distal cutting edge46to efficiently transect tissue as the compression member322is advanced along the length of an end effector. The cutting blade44can be a separate component mated to the compression member322(e.g., held in place by the pins322aand322b, as illustrated), or it can be a sharpened distal end of the compression member322. A cutting blade can be incorporated into any compression member provided for herein or otherwise incorporated into the disclosures provided herein, without departing from the spirit of the present disclosure.

Further information on various aspects of the device100can be found in U.S. Patent Publication No. 2012/0083783 to Davison et al., which is hereby incorporated by reference in its entirety, and U.S. patent application Ser. No. 14/075,839, filed Nov. 8, 2013, and entitled “Electrosurgical Devices,” the entire contents of which were previously incorporated by reference herein. Additional details regarding electrosurgical end effectors, jaw closure mechanisms, and electrosurgical energy-delivery surfaces are described in the following U.S. patents and published patent applications, all of which are incorporated by reference in their entirety and made a part of this specification: U.S. Pat. Nos. 7,381,209, 7,311,709, 7,220,951, 7,189,233, 7,186,253, 7,125,409, 7,112,201, 7,087,054, 7,083,619, 7,070,597, 7,041,102, 7,011,657, 6,929,644, 6,926,716, 6,913,579, 6,905,497, 6,802,843, 6,770,072, 6,656,177, 6,533,784, and 6,500,176, as well as U.S. Patent Publication Nos. 2010/0036370 and 2009/0076506. The various embodiments disclosed in these references can be utilized and combined with the devices and methods described herein.

As mentioned above, one drawback of known tissue transection and sealing devices is that a large amount of force can be required to actuate the device and advance a compression member distally from a proximal end of an end effector. The large amount of force can be required due to the poor mechanical advantage of the compression member when it is positioned close to the connection point of the first and second jaw members. More particularly, tissue captured between the first and second jaw members can act as a spring, resisting the compression forces applied thereto by the first and second jaw members via the compression member. When the compression member is positioned close to the pivot axis of the first and second jaw members, it has a low mechanical advantage and a high level of force is required to compress the tissue. As the compression member is advanced distally away from the pivot axis of the first and second jaw members, its mechanical advantage increases and the force required to advance it further reduces (e.g., similar to how a smaller force applied to a lever far from its fulcrum can counterbalance a larger force applied close to the fulcrum). The devices and methods of the present invention address these and other drawbacks of prior art devices by altering the profile or shape of the closure tracks along which the compression member travels to reduce or modulate the force required to advance the compression member and thereby apply compressive forces to tissue grasped between the first and second jaw members.

FIGS. 4, 8, and 9illustrate one embodiment of an end effector400according to the teachings of the present invention. The end effector400includes a second closure track32bthat extends parallel to a surface of the second jaw member24bsuch that a distance between the second closure track32band an upper surface82of the second jaw member24bis constant along a length of the second jaw member. In the end effector6discussed above, the first closure track32ain the first jaw member24aextends similarly and is parallel to the second closure track32b. Accordingly, a distance between the first and second closure tracks32a,32bwhen the first and second jaw members24a,24bare in the closed position is constant along a length of the end effector.

The end effector400, however, includes a first closure track132having a sloped section36extending from a proximal end of the closure track132to a location adjacent to a distal end of the closure track132. As shown inFIG. 9, the sloped section36continuously increases in height from a starting point to a height H at the location adjacent to the distal end of the closure track132. The height of the closure track132can be measured relative to the lower surface84of the first jaw member24aor relative to the position of the second closure track32bin the second jaw member24bwhen the first and second jaw members are in a closed position (as shown inFIG. 8).

The low starting point and continuously increasing height of the closure track132can provide for a decreased actuation force when the compression member22is positioned at a proximal end of the end effector400, i.e., when its mechanical advantage is lowest. The continuously increasing profile allows for an increase in compression force as the compression member's mechanical advantage increases.

Once the compression member22has traveled over the first sloped section36and reaches a location L adjacent to the distal end of the closure track132, the compression member can travel along a second distal-most section38of the closure track132. The second distal-most section38can be flat relative to the inclined section to ensure that the first and second jaw members are closed to the pre-determined gap distance and that a desired level of compression is exerted on the tissue disposed between the first and second jaw members. In other words, the second distal-most section38is a constant distance H from the lower surface of the first jaw24aor from the second closure track32bof the second jaw member when in the closed position shown inFIG. 8(i.e., a distance between the first closure track132and the second closure track32bis constant over the second section38). As mentioned above, advancing the compression member22along the second distal-most section38to the distal end of the closure track132can ensure that a desired gap and/or compression force is achieved, and complications due to insufficient compression, such as distal tip bleeding, can be reduced.

FIGS. 10 and 11illustrate an alternative embodiment of an end effector1000having a continuously increasing or inclined closure track in which the first closure track232has gradual upward curvature rather than a linear slope. Similar to the first closure track132, a profile of the first closure track232over a first curved section40can increase from a starting point to a height of H′ at a location L′ adjacent to a distal end of the track, as shown inFIG. 11. The inclusion of a gradual upward curvature in the section40can transfer even more compression force to a distal portion of the closure track section40where the mechanical advantage of the compression member22is greatest than is transferred with the linear slope of the closure track132ofFIGS. 8 and 9. In certain embodiments, for example, the shape of the curve can be optimally matched to the changing mechanical advantage of the compression member as it advances along the length of the end effector, thereby minimizing the force required to actuate the device.

A second flat distal-most portion42of the closure track232can meet the curved section40at the location L that is adjacent to the distal end of the closure track. Similar to the portion38described above, the distal-most portion42can maintain a constant desired gap relative to the second closure track32b, lower surface of the first jaw member24a, or upper surface of the second jaw member24bso as to ensure that the jaw members are fully closed to a desired gap distance and compression level. In either embodiment, the force required to translate the compression member22from a proximal end of the end effector400or1000can be reduced due to the altered profile of the first closure track in comparison to profiles of closure tracks in the prior art.

The closure track profiles described herein can have a number of advantages over prior art designs. As already mentioned, providing a decreased distance between the closure tracks of the first and second jaw members at a proximal end of the end effector can reduce the initial force required to actuate the device and delay the application of compression forces until the compression member is located farther from the pivot axis of the first and second jaw members where its mechanical advantage is greater. Some prior art devices, such as those disclosed in U.S. Patent Publication No. 2012/0083783, incorporated by reference above, employ sloped or curved portions of a closure track. However, the devices disclosed in this reference include an initial closure ramp at a proximal end thereof that drives the first and second jaws to a fully closed position before reducing the compression. The location of the initial closure ramp at the proximal-most end of the closure track requires a significant actuation force at precisely the location where the mechanical advantage of the compression member is weakest. Accordingly, the gradual and continuously increasing closure track profiles described herein can have advantages over the prior art in that higher compression forces are delayed until the compression member has advanced sufficiently to increase its mechanical advantage, in turn minimizing the overall force required to actuate the surgical device.

FIGS. 12 and 13illustrate still another alternative embodiment of an end effector1200having a first closure track1202configured to modulate the force required to advance a compression member22along the track. As illustrated inFIG. 13, the first closure track1202has an alternating profile wherein a distance between the first closure track1202and the second closure track32bwhen the first and second jaw members24a,24bare in a closed position repeatedly alternates between a first distance and a second distance that is greater or less than the first distance, depending on the embodiment. The repeated alternation of the distance between the closure tracks1202and32bcan result in repeated alternation of compression forces applied to tissue between a first and second value (where the second value is either higher or lower than the first value, depending on which value corresponds to a peak and which to a valley in the profile). Additionally, in certain embodiments a minimum number of repeated oscillation cycles can be provided over the length of the closure track. For example, in some embodiments a minimum of at least two full alternation cycles (e.g., an increase to a maximum value and a decrease to a minimum value) can be provided. The inclusion of at least two full alternation cycles can more effectively promote tissue sealing, as described in more detail below.

As with the other embodiments described above, the repeatedly alternating profile can continue over a first proximal-most portion1204of the first closure track1202and can extend from a proximal-most end of the closure track1202to a location L″ that is adjacent to a distal end of the closure track. A second, flat or constant portion1206can extend from the location L″ to a distal-most end of the first closure track1202. Over this second portion1206, a distance H″ between the first closure track1202and the second closure track32bcan remain constant so as to ensure a desired gap width or compression level is achieved before actuation is complete. This second portion1206is positioned at a distal-most end of the closure track1202because it is the greatest distance from the pivot axis of the first and second jaw members24a,24band therefore provides the greatest mechanical advantage for the compression member22(and consequently the lowest required user actuation force to achieve the desired compression level).

An alternating closure track profile does not necessarily reduce the initial force required to actuate the device in the same manner as the sloped or curved continuously rising profiles, but can still provide modulation of the required actuation force by temporarily reducing the compression on the tissue. Further, the alternating closure track profile can have particular advantages when used in combination with RF energy delivery to seal tissue. This is because RF energy can cause tissue to partially desiccate as it heats, so as tissue is sealed its volume can be reduced, similar to cooking a beef patty on a grill. The repeated alternation of compression forces on the tissue concurrent with RF energy application can serve to squeeze liquid out of the tissue, similar to pressing a beef patty on a grill with a spatula, thereby further reducing the volume of the tissue between the first and second jaw members. As the volume of tissue decreases, the compression member can more easily be advanced through the tissue. Additionally, the repeated oscillation can allow more time for the RF energy to thoroughly fuse the tissue, thereby creating a better seal.

There are a number of different variations and modifications that can be employed with an alternating closure track profile.FIGS. 14A-17, for example, illustrate one embodiment of an end effector1400in which a first closure track332has an irregularly alternating profile. More particularly, the closure track332can have a profile similar to a wave function in which the wavelength decreases from a proximal end to a distal end of the end effector1400. Referring toFIGS. 14A and 14B, a perspective view of the first closure track332extending along the first jaw member24ais illustrated. The figure shows that the first closure track332is formed on either side of a compression member channel1402that extends along a length of the first jaw member24a. A compression member1404, similar to the compression member322discussed above, is slidably disposed within the channel1402and includes at least one protrusion1406that rides along the first closure track332. Because the compression member1404also includes a protrusion riding along a second closure track (not shown) in the second jaw member24b, the compression member1404is prevented from moving vertically within the plane of the first and second jaw members (i.e., in a direction perpendicular to a longitudinal axis of the end effector, or the up/down directions ofFIGS. 14A and 14B). Accordingly, as the compression member1404is advanced along the length of the end effector, the interaction between the protrusion1406and the first closure track332will cause the first jaw member24ato pivot relative to the second jaw member24b, thereby exerting differing levels of compression on tissue disposed between the first and second jaw members.FIGS. 15 and 16illustrate the embodiment shown inFIGS. 14A and 14Bfrom a side perspective, again showing how the protrusion1406formed on the compression member1400rides along the first closure track332and causes relative movement between the first and second jaw members24a,24b.

Returning to the concept of irregular alternation introduced above,FIG. 17illustrates an embodiment of a closure track profile in which a wavelength λ1is larger than each subsequent wavelength, λ2, λ3, etc. Other combinations of wavelengths can also be incorporated into such an embodiment, and thus in other embodiments some subsequent wavelengths can be shorter, longer, or the same size as preceding wavelengths.

In another embodiment shown inFIG. 18, a closure track432can have an alternating profile similar to a wave function in which the amplitude increases or decreases with each successive oscillation (i.e., the amplitude can either increase or decrease from a proximal end of the end effector to a distal end of the end effector). In other words, a distance between the first closure track and the second closure track can repeatedly alternate between any number of values (e.g., three, four, etc.) and each successive value can be greater or less than the preceding values. In such an embodiment, the closure track432can have a constant wavelength, or it can have a variable wavelength similar to the closure track332discussed above. As shown inFIG. 18, the amplitude height A1is larger than that of each subsequent amplitude A2, A3, etc. Other combinations of amplitudes can also be incorporated into such an embodiment, and thus in other embodiments some subsequent amplitudes can be smaller, larger, or the same size as preceding amplitudes.

In still another exemplary embodiment shown inFIG. 19, a closure track532can have an alternating profile similar to a sinusoidal wave function wherein the wavelength and amplitude is substantially constant over the length of the closure track. In any of these embodiments, the amount of compression between the first and second jaws can oscillate as a function of the distance between the first closure track and the second closure track when the compression member traverses the track.

As described above, the alternating track profiles shown inFIGS. 12-19can have an additional benefit of increasing tissue seal quality in applications where RF energy delivery is used. This is because the compression of the first jaw member24aagainst the second jaw member24bcan be higher at a peak of each oscillation, which can allow the jaws to push excess fluids out of the tissue. Conversely, the compression of the first jaw member against the second jaw member can be lower at a valley of each oscillation, which can allow the RF energy to heat the tissue and thereby make it easier to compress. The alternating levels of tissue compression provided by the alternating closure track profiles can allow for a more effective sealing of tissue than is otherwise possible.

Finally, and as noted above, the second closure track32bin any of these embodiments can have either a flat or constant profile as known in the art, or can include one or more sloped, curved, or alternating profiles similar to the first closure tracks described above. In other words, a distance between a second closure track32band an upper surface82of a second jaw member24bcan be constant from a proximal end of the closure track to a distal end of the closure track, or the distance can vary along the length of the closure track in any of the manners described herein. Indeed, to the extent any alternating profile provided for herein is illustrated with one particular embodiment, a person having skill in the art can incorporate such profiles into other embodiments provided for herein or otherwise known to those skilled in the art.