Articulated Shaft of a Surgical Device

Abstract

A surgical instrument is disclosed having a handle and an elongated shaft assembly extending distally from the handle. The elongated shaft assembly has a longitudinal axis and is articulatable between a fully bent configuration and a less bent configuration. The elongated shaft assembly includes a first tubular member having a first flexible portion with a first preferential bending direction. The elongated shaft assembly also includes a second member including a second flexible portion axially secured to the first tubular member at a location distal to the first flexible portion. The first flexible portion is defined by a plurality of cutouts, each cutout defining a cutout longitudinal axis transverse to the shaft longitudinal axis, and the plurality of radial cutouts having an asymmetric shape about the cutout longitudinal axis.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 62 / 962,036, filed on January 16, 2020, entitled "Articulating Shaft of a Surgical Device", which is hereby incorporated by reference in its entirety. This application also claims the benefit of U.S. Provisional Patent Application No. 62 / 967,300, filed on January 28, 2020, entitled "Articulating Shaft Liner of a Surgical Device", which is hereby incorporated by reference in its entirety.

[0002] The present invention relates to the field of surgery, and more particularly, to articulated surgical devices and methods of accessing target tissue using articulated devices.

Background Art

[0003] The present invention relates to an arthroscopic or endoscopic device. In arthroscopic examinations, the number of portals through the patient's skin is minimized to reduce patient scarring and improve the patient's recovery rate. The position may not be favorable for accessing all parts of the tissue being treated within the joint, and therefore, some devices may be selectively articulable or may have a pre-bent or angled end. The portal is preferably sized using a 5.0 mm cannula, but this limits the ability of the pre-bent device inserted therethrough. This limitation for smaller cannula sizes also tends to compromise the rigidity of the articulating shaft, and a typical articulating shaft may bend and not retain its shape when in contact with tissue. Thus, a surgeon may need to use a fixed device to treat tissue in one mode, such as bulk tissue removal where much of the heavy lifting may be done, and the articulating device can be brought in for precise tissue removal or removal in locations not reachable with the fixed device. Therefore, a device that can articulate and yet be sufficiently rigid to maintain its shape during use is needed.

[0004] The articulating portions of these shafts can include a plurality of lateral cuts or cutouts disposed along at least a portion of the length of the shaft through the shaft. These cutouts can expand and contract during articulation. In some applications, the plurality of cutouts can be covered by a thin and flexible sheath. The sheath can, for example, electrically isolate a portion of the shaft for an energy-based device. An example of the distal end 100 of a device having a sheath 120 can be seen in FIGS. 7A and 7B. As a first non-limiting example in an energy-based device, the tubular shaft 110 can be electrically active, and the sheath 120 can limit the exposed portion of the electrically active surface. As a further non-limiting example, this sheath 120 can limit the ingress of conductive fluid through the tubular shaft during arthroscopic examination and limit unintended electrical pathways within the energy-based device. In a grasping device, the tubular shaft 110 can house a movement linkage, and the sheath 120 can prevent fluid and debris from entering the tubular shaft 110 through the radial cutout 140 and interfering with the linkage function. This sheath 120 is preferably configured to bend the articulation connection and interfere minimally, and because the radial cutouts expand and contract as shown in FIGS. 7A and 7B, with repeated articulation movement, wrinkles can form and tend to move into the radial cutout 140. More specifically, FIG. 7A shows a view of the distal end 100 of an articulated device in a straight configuration covered by a sheath 120. FIG. 7B shows a view of the distal end 100 in an angled configuration having a sheath 120 with wrinkles 121. FIG. 7A shows a cross-section of the distal end 100 in a straight configuration having a sheath 120 that begins to move between the cutouts 140. FIG. 7B shows a cross-section of the distal end 100 in a bent or angled configuration having a sheath 120 partially disposed within at least one cutout 140. This movement can interfere with the articulation connection and torsional stiffness of the device in an articulated configuration. In FIG. 7B, the wrinkles 121 within at least a portion of the cutout 140 limit how much the cutout can close, and thus the device can be limited to a reduced articulation connection angle offset α.This can also cause devices that require additional force for articulation, which can be uncomfortable for the surgeon. Therefore, means are needed to limit movement of the sheath 120 into or between the radial cutouts along the shaft, as the tubular shaft minimally adds bulk to the shaft or significantly affects the ease of articulation.

Brief Description of the Drawings

[0005] For a detailed description of the exemplary embodiments, reference is now made to the accompanying drawings.

[0006]

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[0007] Generally, the present disclosure describes a surgical device having an articulated tubular member configured to direct an articulation and having a cut or slot therethrough. The device may be sized to fit a 5.0 mm cannula underneath and to articulate to allow access to the anatomical structure of the joint. The articulation may be achieved by a flexible portion including at least one cutout configured to provide improved shaft bending strength and torsional stiffness when in a fully articulated configuration compared to other articulation devices.

[0008] The present disclosure also describes an articulated surgical device including a thin flexible sheath covering at least a portion of the cutout. A sleeve liner, which may include angled cuts, may be coaxially disposed over the cutout to limit movement of the thin flexible sheath into the radial cutout during articulation. The liner may define a thin-walled high melting point tube that fits between an insulating sheath and a metal shaft that stretches or slides when the device articulates. The surgical device may be an RF device, where the tubular member may be electrically coupled as an electrode and the sheath limits exposure of the outer surface of the tube, thereby limiting the position and size of the electrode.

[0009] A first exemplary embodiment of a surgical instrument may include a handle and an elongate shaft assembly extending distally from the handle. The elongate shaft has a longitudinal axis. The elongate shaft assembly is articulable between a fully bent configuration and a less bent configuration. The elongate shaft assembly includes a tubular member that includes a flexible or articulable portion having a first preferred bending direction. Also, there is an elongate member coaxially disposed within the tubular member and directly coupled to the tubular member at a location distal of the flexible portion. Axial tension on the elongate member may articulate the shaft assembly. The flexible portion is defined by a plurality of cutouts through the thickness of the tubular member. Each cutout defines a cutout longitudinal axis. Each cutout includes a tapered opening portion defined by a pair of linear edges facing each other. The linear edges may be defined by which side of the cutout in which they are located. For example, a pair of linear edges may be referred to as a proximal linear edge and a distal linear edge. At least one of the plurality of cutouts defines an asymmetric shape about its corresponding cutout longitudinal axis, and the asymmetric shape is configured to increase a circumferential contact length between the pair of linear edges when the flexible portion is in a fully bent configuration.

[0010] In some embodiments, at least one of the cutouts defines a keyhole shape having a bulbous closed end, and the bulbous closed end is asymmetric about the longitudinal axis of the cutout. The bulbous closed end may define a proximal concave surface and a distal concave surface that are continuous with each other, and the distal concave surface defines a smaller radius of curvature than the proximal concave surface. The bulbous closed end may define a maximum axial length that is less than 50% greater than the maximum axial length of the tapered opening portion when the instrument is in a less bent configuration. In a fully bent configuration, the proximal linear edge and the distal linear edge of each of the plurality of cutouts may be aligned with each other to form a smooth, curved shaft surface without steps. The asymmetric shape of the cutout may be configured to rotate the distal edge towards the proximal edge so as to align when engaged. Each of the tapered opening portions of the plurality of cutouts defines an angular opening when the shaft is in a less articulated configuration, and in a neutral or non-articulated configuration, the most distal cutout of the plurality of cutouts has a smaller angular opening than all of the remaining plurality of cutouts.

[0011] Another embodiment of the surgical instrument disclosed herein may include a handle and an elongated shaft assembly extending distally from the handle. The elongated shaft assembly includes a tubular member that includes an articulable portion defined by at least one cutout through the wall of the tubular member. The elongated member is also coaxially disposed along the tubular member and coupled to the tubular member at a position distal to the articulable portion. Actuation of the elongated member bends the articulable portion and angularly offsets the distal end of the tubular member relative to the proximal end of the elongated shaft. At least one cutout defines a longitudinal axis that traverses the shaft longitudinal axis, and at least one cutout defines a shape that is asymmetric about the cutout longitudinal axis. The asymmetric shape is shaped to increase the circumferential contact length between the proximal circumferential edge and the distal circumferential edge of each cutout when the distal end is bent with a maximum angular offset.

[0012] In some embodiments, at least one cutout defines a keyhole shape having a bulbous closed end, the bulbous closed end defining a concave proximal surface and a concave distal surface facing the concave proximal surface and having a different radius of curvature than the concave proximal surface. The concave proximal surface may define a larger radius of curvature than the concave distal surface. The asymmetric shape may be configured to form a continuous, unbroken curve along the articulable portion when the distal end is bent at the maximum offset angle. The at least one cutout may include at least two cutouts, each of the at least two cutouts defining an angular opening, and the angular opening of the most distal cutout of the at least two cutouts is formed with a smaller angular opening than all of the remaining cutouts.

[0013] Another exemplary additional surgical instrument embodiment is disclosed herein that includes a handle and an elongate shaft assembly extending distally from the handle. The elongate shaft assembly includes a tubular member having an articulable portion defined by a plurality of axially spaced cutouts through the tubular member. The elongate shaft assembly also includes a sheath that is coaxial with the tubular member and that includes covering the tubular member including covering the articulable portion. The elongate shaft member also includes a liner disposed between the sheath and the tubular member along the articulable portion. The liner includes at least one discontinuous portion through the thickness of the liner and is configured to allow the articulable portion to articulate while simultaneously blocking movement into the cutouts of the sheath.

[0014] In some embodiments, the discontinuity may include a helical cut around and along a portion of the liner. The discontinuity may comprise a helical cut having an axial gap length configured to increase the flexibility of the liner while simultaneously blocking movement to the radial cutout of the sheath. The axial gap length may be formed by the liner extending or elongating axially. The tubular member may be conductive, and the sheath may be an electrical insulator configured to limit the exposed conductive outer surface of the tubular member. The liner may be a nylon sleeve. Substantially each rotation of the helical cut may occur within a respective distance along the length of an articulable portion including at least two of the plurality of cutouts. Substantially each rotation of the helical cut may occur within a respective distance along the axial length of the articulable portion so as to cover at least three of the plurality of radial cutouts.

[0015] Additional exemplary embodiments may be disclosed that may include a handle and an elongated shaft assembly extending distally from the handle. The elongated shaft assembly may include a tubular member having a flexible portion defined by a plurality of radial cutouts spaced axially along the tubular member. The radial cutouts may open and close during flexion. The elongated shaft assembly may also include a sheath that is coaxial with the tubular member and covers the tubular member including covering the flexible portion. The elongated shaft assembly may also include a sleeve or liner coaxially disposed between the sheath and the tubular member and along the flexible portion. The spiral cut may extend along and around a portion of the sleeve, and the spiral cut and the sleeve are generally configured to articulate the flexible portion of the tubular member, where the radial cutouts expand and contract while simultaneously restricting movement to the radial cutout of the sheath.

[0016] In some exemplary embodiments, the sleeve may be extended or formed to include at least one elongated axial gap. This can be formed by extending the sleeve such that the spiral cut edges move away from each other. The axial gap can be configured to enhance the flexibility of the sleeve while maintaining a barrier for moving the sheath into the radial cutout. In some exemplary embodiments, the tubular member is conductive and the sheath is an electrical insulator configured to limit the exposed conductive outer surface of the tubular member. In some exemplary embodiments, the sleeve includes nylon. In some exemplary embodiments, substantially each rotation of the spiral cut occurs within a respective distance along the axial length of three flexible portions of the plurality of radial cutouts. In some exemplary embodiments, substantially each rotation of the spiral cut occurs within a respective distance along the axial length of two flexible portions of the plurality of radial cutouts.

[0017] A further exemplary embodiment of a surgical instrument may include a handle and an elongated shaft assembly extending distally from the handle. The elongated shaft assembly may include a tubular member having flexible portions defined by a plurality of transverse cutouts spaced axially along the tubular member. The elongated shaft assembly may also include a sheath that is coaxial with the tubular member and covers the flexible portions, and a sleeve coaxially disposed between the sheath and the tubular member and along the flexible portions. The sleeve can bend, stretch, and articulate the flexible portions of the tubular member while simultaneously restricting movement of the sheath between the transverse cutouts.

[0018] In some exemplary embodiments, the tubular member can be conductive and the sheath is an electrical insulator configured to limit the exposed conductive outer surface of the tubular member. In some exemplary embodiments, the sleeve can define a thin-walled high-temperature sleeve. In some exemplary embodiments, the sleeve can include a plurality of incisions oriented at an angle with respect to the longitudinal axis of the sleeve to increase the flexibility of the sleeve while simultaneously restricting movement between the lateral cutouts of the sheath. In some exemplary embodiments, the sleeve can include a single elongated helical cut configured to increase the flexibility of the sleeve while simultaneously restricting movement between the lateral cutouts of the sheath. In some exemplary embodiments, each rotation of the single helical cut can occur within respective distances along the lengths of three flexible portions of the plurality of lateral cuts. In some exemplary embodiments, each rotation of the helical cut occurs within respective distances along the lengths of two flexible portions of the plurality of lateral cutouts. In some exemplary embodiments, the helical cut can include an axial opening to further increase the flexibility of the sleeve while simultaneously restricting movement between the radial cutouts of the sheath.

[0019] Notation and Terminology Certain terms are used throughout the following description and claims to refer to particular system components. As will be appreciated by those skilled in the art, companies that design and manufacture electro-surgical systems may refer to components by different names. This document is not intended to distinguish between components that differ in name but not in function.

[0020] In the following discussion and claims, the terms "including" and "comprising" are used in an open-ended fashion and should, therefore, be interpreted to mean "including but not limited to." Also, the term "couple" or "couples" is intended to mean either an indirect or a direct connection. Thus, when a first device is coupled to a second device, that connection may be through a direct connection or through an indirect connection via other devices and connections.

[0021] References to items in the singular include the possibility that there are a plurality of the same items. More specifically, as used herein and in the appended claims, the singular forms "a," "an," "said," and "the" include the plural unless the context clearly dictates otherwise. Further, note that the claims may be drafted to exclude any optional element. Thus, this specification serves as a basis for precedence for using such exclusive terms as "solely," "only," etc. in connection with the listing of elements of the claims or the use of "negative" limitations. Finally, unless defined otherwise, all technical and scientific terms used herein are to be understood as having the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0022] "Ablation" shall mean the removal of tissue based on tissue interaction with plasma.

[0023] "Ablation mode" shall refer to one or more characteristics of ablation. The absence of ablation (i.e., the absence of plasma) shall not be considered an "ablation mode."

[0024] "Active electrode" shall mean the electrode of an electrosurgical wand that produces an electrically induced tissue change effect when in contact with or in proximity to a treatment target tissue.

[0025] The "return electrode" shall mean an electrode of an electrosurgical wand that serves to provide a current path for the charge with respect to the active electrode and / or an electrode of the electrosurgical wand that itself does not cause an electrically induced tissue change effect on the treatment target tissue.

Embodiments for Carrying Out the Invention

[0026] The following discussion is directed to various embodiments of the present invention. One or more of these embodiments may be preferred, but the disclosed embodiments should not be construed as, or otherwise used to, limit the scope of the present disclosure, including the claims. Additionally, those skilled in the art will understand that the following description has broad application and is a consideration of any embodiment.

[0027] Before the present invention is described in detail, it should be understood that the present invention may be subject to various changes or modifications and equivalents may be substituted without departing from the spirit and scope of the present invention, so it is not limited to the specific variations described herein. As will be apparent to those skilled in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has individual components and features that can be easily separated from, or combined with, the features of any of several other embodiments without departing from the scope or spirit of the present invention. Additionally, many modifications may be made to adapt a particular situation, material, composition of matter, process, process act, or step to the objective, spirit, or scope of the present invention. All such modifications are intended to be within the scope of the claims made herein.

[0028] The methods recited in this specification can be performed in any order of the recited events that are reasonably possible, as well as in the order of the recited events. Further, when ranges of values are provided, all intervening values between the upper and lower limits of that range, as well as any other recited or intervening values within the stated range, are understood to be encompassed within the present invention. Additionally, any optional features of the described variations of the invention are contemplated to be described and claimed independently or in combination with any one or more of the features described herein.

[0029] All existing subject matter described herein (e.g., publications, patents, patent applications, and hardware) is hereby incorporated by reference in its entirety, except where the subject matter might conflict with the subject matter of the present invention (in which case, what is present herein prevails). The items being referenced are provided solely for the purpose of their disclosure prior to the filing date of the present application. No provision of this specification should be construed as an admission that the present invention does not have the right to antedate such material by virtue of prior invention.

[0030] References to items in the singular include the possibility that there are a plurality of the same items. More specifically, as used herein and in the appended claims, the singular forms “a,” “an,” “said,” and “the” include plural referents unless the context clearly dictates otherwise. Further, note that the claims can be drafted to exclude any optional elements. Accordingly, this specification is intended to serve as a basis for using such exclusive terms as “solely,” “only,” etc. in connection with the recitation of claim elements or the use of “negative” limitations. Finally, unless defined otherwise, all technical and scientific terms used herein are to be understood as having the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0031] The inventors recognize that there may be situations where it is desirable to provide an articulatable elongated shaft assembly having sufficient rigidity in an articulated configuration. Such rigidity can help maintain the distal tip of the elongated shaft assembly at a desired position and / or orientation during a surgical procedure and / or avoid excessive deflection of the shaft assembly when a force is applied to the distal tip. For example, the distal tip may be pressed against a surface when deploying a fastener into tissue, and the rigidity of the elongated shaft assembly can limit deflection of the tip to be less than a desired threshold deflection for a given force applied to the distal tip. As a further example, the distal tip may elevate or move tissue to gain better access and treat target tissue by electro-surgery, and the rigidity of the elongated shaft assembly can limit deflection of the tip while elevating the tissue.

[0032] As used herein, the term "distal direction" within a surgical device may refer to a direction extending along the longitudinal axis of the surgical device toward the distal end of the surgical device at which a desired operation is performed. Accordingly, the "proximal direction" may refer to a direction oriented in an opposite direction to the distal direction such that it can be oriented along the longitudinal axis of the surgical device away from the distal end of the surgical device at which the desired operation is performed.

[0033] According to some embodiments, an elongate shaft assembly extends distally from a handle of a surgical instrument. The elongate shaft assembly includes an articulable portion that may be articulably connected in at least one direction between a first position that may correspond to a non-articulated configuration and a second position that may correspond to a fully articulated configuration in which a distal tip is oriented at an angle (e.g., an articulation angle) relative to a portion of the elongate shaft assembly that is proximal to the articulable portion. When in the first position, a longitudinal axis passing through the articulable portion may be aligned with a longitudinal axis of a proximal portion of the elongate shaft assembly. Correspondingly, when in the fully articulated configuration, a distal end of the elongate shaft assembly and a longitudinal axis of the articulable portion are oriented at an articulation angle relative to the longitudinal axis of the proximal portion. In the fully articulated configuration, a substantial portion of the edges of the cutouts along the device shaft are in contact with each other. In one embodiment, the articulation angle of the fully articulated configuration may be between 15 degrees and 90 degrees, although it should be understood that the present disclosure is not limited to any particular range of articulation angles. Further, in some embodiments, the articulable portion may be movable to one or more additional articulated positions between a non-articulated (i.e., straight) configuration and the fully articulated configuration.

[0034] The surgical devices described herein may be made from any desirable material or combination of materials. In some examples, the surgical devices described herein may be made from sterilized materials and / or sterilizable materials using any suitable method including, but not limited to, heat, radiation, and / or pressure. Further, the materials may be sterilized before, during, or after assembly and packaging to maintain sterility.

[0035] In some embodiments, the surgical instrument may include an elongate shaft assembly that includes a first articulating shaft and a second articulating shaft disposed coaxially with respect to the first articulating shaft. The first and second articulating shafts may include flexible portions that form articulatable portions of the elongate shaft assembly, and the first and second articulating shafts are axially fixed relative to each other at a location distal to the articulatable portion. The proximal portions of the first and second articulating shafts are axially displaceable relative to each other and can move the articulatable portion of the elongate shaft assembly between a first position and a second position. For example, the proximal portions of the first and second articulating shafts may be displaced relative to each other to selectively place the first and second articulating shafts in opposing states of tension and / or compression. As discussed in more detail below, such tension and / or compression forces are transmitted through the appropriate structure of the articulatable portion to apply and / or release a bending moment to the first and second articulating shafts, thereby moving the articulatable portion between a non-articulated configuration and an articulated configuration. In some embodiments, the bending moment causes the articulatable portion to move from a non-articulated configuration, which may correspond to a relaxed configuration of the elongate shaft assembly, to an articulated configuration. However, it should be understood that the present disclosure is not limited to embodiments in which the bending moment moves towards the articulated configuration. For example, in some embodiments, the fully articulated configuration may correspond to a relaxed (i.e., stress-free) state of the elongate shaft assembly, and the application of a bending moment (or other appropriate stress) may move the elongate shaft assembly towards a non-articulated (i.e., straight) configuration.

[0036] In some embodiments, the surgical instrument may include an articulating control operable by a user to selectively move an articulable portion of the elongated shaft assembly of the device between a non-articulated configuration and a fully articulated configuration. The articulable portion of the elongated shaft assembly may be formed by one or more flexible portions of the associated shaft that enable articulation. For example, the flexible portion of the shaft may extend substantially laterally across the diameter of the shaft and may include a plurality of cutouts disposed along at least a portion of the length of the various shafts that make up the elongated shaft assembly to provide the desired flexibility. While still allowing flexion of the articulable portion of the elongated shaft assembly, it may be beneficial to provide the desired rigidity of the elongated shaft assembly. Thus, in some embodiments, the particular dimensions and arrangements of the cuts, spines, and / or other suitable features of at least the first articulating shaft of the elongated shaft assembly may be selected to provide the desired rigidity. In one embodiment, the spine may have a tapered configuration where the distal portion of the spine is narrower than its proximal portion. This may provide an increase in the bending rigidity of the elongated shaft assembly at the proximal end of the spine and an increase in the flexibility of the assembly at the distal end. Such a configuration may enable the distal end of the articulating shaft assembly to be progressively stiffer at the proximal end of the articulable portion while having sufficient flexibility to articulate to a desired articulated position. Without being bound by theory, such a configuration may help avoid unwanted deflection of the elongated shaft assembly during use, such as when a user presses the distal end of the shaft assembly against a surface to deploy a fastener into tissue.

[0037] In addition to the above, the inventors recognize that the number, size, and / or spacing of the cuts in the shaft of the articulable portion of the elongate shaft assembly can affect the resulting stiffness of the elongate shaft assembly in the non-articulated configuration and / or the articulated configuration. For example, the inventors have discovered that an articulated shaft having a greater number of cuts and smaller cut sizes in the articulable portion can provide an improvement in stiffness while allowing the desired amount of articulation in the articulable portion. Thus, in some embodiments, the number of cuts, cut size, and / or cut spacing can be selected to provide the desired stiffness to the elongate shaft assembly. Specific sizes and spacing of the cuts are discussed in more detail below with respect to specific embodiments.

[0038] As described above, the elongate shaft assembly can include first and second articulated shafts that are placed in opposing states of tension and compression when the articulable portion of the elongate shaft assembly is in the articulated configuration. In some embodiments, the articulated shaft placed in compression can include a plurality of cuts sized and shaped such that opposing faces of each cut contact each other when the articulable portion is fully articulated. For example, the inventors have understood that such a configuration can impart additional stability and / or stiffness to the distal portion of the elongate shaft assembly when in the articulated configuration.

[0039] Referring to the figures, specific non-limiting embodiments are described in more detail. Since the present disclosure is not limited to only the specific embodiments described herein, it should be understood that the various systems, components, features, and methods described in connection with these embodiments can be used individually and / or in any desired combination.

[0040] FIG. 1 shows one embodiment of a surgical instrument 2. The surgical instrument 2 includes a handle 4 and an elongated shaft assembly 6 that extends distally from the handle toward a distal end 20. The distal end 20 can provide various functions including, but not limited to, a light source, visualization, energy-based tissue treatment such as an electrosurgical device, tissue grasping, or a fastener that can be deployed. The elongated shaft assembly 6 includes an articulable portion 8 that can be movable between a non-articulated position and one or more articulated (i.e., curved or bent) positions. The non-articulated position can define a straight configuration of the articulable portion 8. The articulation of the articulable portion 8 can be controlled by an articulation control 10 such as a rotatable and / or axially displaceable knob, handle, lever, or other interface that can be moved or pushed. The articulable portion 8 can angularly offset the distal end 20 from a non-articulated connection configuration to a plurality of offset angles. The surgical instrument 2 can also include other controls or triggers 12 for grasping tissue, actuating a fastener deployment system, or, for example, actuating an energy-based treatment.

[0041] The articulable portion 8 of the elongated shaft assembly can be moved using the articulation control 10 between at least a first position such as a non-articulated position and a second position such as a fully articulated position. In this example, the control 10 can rotate about the longitudinal axis of the instrument 2. Depending on the embodiment, the articulable portion 8 can be moved to one or more preselected articulated angles, or the articulable portion 8 can be adjusted to one or more arbitrary (i.e., not preselected) articulated angles.

[0042] Figure 2 shows a side view of the distal end 20, including the articulable portion 8 of the elongated shaft assembly 6 of the surgical instrument 2 extending distally from the handle 4. The distal end 20 may include other elements such as a sheath, wire, cable, or rod, either external or internal to the shaft assembly, which are removed from the figure to avoid unduly complicating the drawing. The distal end portion may include an electrode, tube, or grasping jaw that may extend from the distal end, which is removed from the figure to avoid complicating the drawing. For example, the outer shaft 34 may define a return electrode and, thus, be conductive. The isolated active electrode of the electrosurgical instrument may be coupled to the most distal end of the outer shaft 34, as described in more detail with reference to FIGS. 10A-10C.

[0043] The elongated shaft assembly may include an inner shaft 32 and an outer shaft 34, with the inner shaft 32 extending within the outer shaft 34. As described herein, the shafts (32, 34) are constructed and arranged to move the articulable portion 8 between a non-articulated position and one or more articulated positions. The shafts (32, 34) of the elongated shaft assembly may be coaxially arranged relative to each other, and both shafts may define an elongated lumen along their respective axes, at least along the articulable portion. Although a particular arrangement of the shafts is shown in the figure, it should be understood that other arrangements may also be appropriate. For example, in an alternative embodiment, the inner shaft 32 may be a flexible pull rod without a lumen or cutout.

[0044] As shown, the articulatable portion 8 may include a plurality of cutouts (40, 42) that define one or more splines extending along the length of the shafts (32, 34). Looking at both FIGS. 2 and 6, the inner shaft 32 may include a first plurality of cutouts 40 that extend laterally through the shaft 32. The first plurality of cuts 40 are axially spaced from each other along the length of the articulatable portion 8 on the first side of the shaft 32. The second opposing side of the shaft 32 has a continuous and unbroken length and may define a spline 44. Similarly, at least as shown in FIGS. 2 and 3A, the outer shaft 34 includes a plurality of cutouts 42 that extend from the first side of the shaft 34 generally orthogonally to the shaft longitudinal axis. The cutouts 42 are axially spaced from each other. The second opposing side of the shaft 34 defines a continuous and unbroken length and may define a spline 46. The cutouts and splines of each shaft may be disposed relative to each other on opposing faces of the articulatable portion 8.

[0045] The inner shaft 32 and the outer shaft 34 may preferably be attached to each other at an attachment point 62 that is distal to the articulatable portion 8. This may axially fix the inner shaft and the outer shaft to each other at the attachment point 62. In the illustrated embodiment, the attachment point 62 is located adjacent the distal end of the inner shaft 32, and the outer shaft may extend distally beyond the inner shaft 32. The two shafts 32, 34 may be attached in any suitable manner, such as with an adhesive, one or more fasteners, one or more pins, one or more welds, and / or any other suitable form of connection.

[0046] The axial forces and / or displacements applied to corresponding proximal portions of the inner shaft 32 and the outer shaft 34 by the distal attachments 62 of the two shafts 32, 34 can place these shafts in a state of tension and / or compression. For example, the proximally directed forces and displacements applied to the proximal portion of the inner articulating shaft 32 can generate tensile stresses in the inner shaft 32. Similarly, the application of corresponding distally directed forces and displacements to the proximal portion of the outer shaft 34 can generate compressive stresses in the outer articulating shaft. These opposing tensile and compressive stresses may be transmitted through the opposing splines 44 and 46 of the respective shafts, both of which are offset from the neutral bending axis of the overall elongated shaft assembly. This results in a bending moment in the articulating shaft, causing the articulating shaft to bend and move the elongated shaft assembly to an articulated position.

[0047] Proximally and distally directed forces and displacements can be applied to the shafts via any suitable flexion control system, respectively. For example, a surgical instrument may include a joint control 10 to selectively move the articulable portion 8 of the elongated shaft assembly between a non-articulated connection position and an articulated connection position. Depending on the particular embodiment, the joint control can be coupled to the articulating shafts (32, 34) of the elongated shaft assembly via any suitable structure to control the articulation. For example, the control 10 may be operably coupled to the inner shaft 32, and actuation of the control 10 may axially contract the inner shaft 32 proximally, while the outer shaft 34 is fixed and remains stationary.

[0048] Next, move to FIG. 3A showing only the outer shaft 34 in the neutral configuration, which can be in a straight configuration. The inner shaft 32 has been removed so as not to unduly complicate the figure. Referring to the articulation connection and the resulting bending of the shafts when articulated, the outer shaft 34 defines an inner radial side surface 35 and an outer radial side surface 36 (spine) of the resulting bend. When articulated, the corresponding edges of each cutout 42 move towards each other and engage with each other, and the inner radial side surface 35 changes from the length of the shaft having the cutout opening to a continuous, smooth and unbroken surface (when fully articulated). The opposing outer side surfaces 36 of the shaft include spines 46 and may therefore not have cutouts. Although side views of the shaft 34 are shown throughout these figures, each cutout 42 extends through the tubular shaft such that the cutout is a mirror image with respect to a vertical plane along the longitudinal axis L.

[0049] Each of the outer shaft cutouts 42 may define a keyhole shape having a longitudinal axis L that traverses the longitudinal axis L of the shaft 34. c The keyhole shape includes a tapered or angled opening 42a that extends from the inner side 35 and ends at a rounded or spherical closed end 42b. The closed end 42b may also be described as the end of a kidney bean. The end 42b is configured to separate bending stress to a point within each cut 42. The angled opening portion 42a defines a linear tapered opening and tapers to a smaller opening as the opening portion 42a extends away from the inner radial side surface 35 towards the rounded end 42b. The keyhole-shaped cutout 42 is not symmetric about the longitudinal axis L. c The keyhole-shaped cutout 42 is not a mirror image about a vertical plane that is normal to the longitudinal axis L of the instrument and extends along the longitudinal axis L. c The angled opening 42a is defined by a distal edge 43a and a proximal edge 43b that may be linear. The angled portion 42a may taper uniformly and is axially L cOne side thereof may taper at an angle (θ) that is evenly divided. The angled opening defines a distal edge 43a that is longer than the proximal end 43b. The length of the distal edge of the tapered opening 42a further extends in a direction transverse to the longitudinal axis L, whereby a larger arc segment of the tubular shaft annular wall can be removed. For example, referring to the figure shown in FIG. 3A, for a tubular shaft outer diameter of about 0.2 inches, the distal end can extend about 0.117 inches in a direction transverse to the longitudinal axis of the shaft through this exemplary tubular shaft, while the proximal end can extend about 0.110 inches. The difference between the two edge lengths can depend on the number of cutouts, the bending angle at the fully articulated position, and the size of the angled opening. The larger the angled opening, the greater the difference between the proximal and distal lengths may be. Each cutout 42 is further asymmetric, and the kidney bean-shaped end defines a more tightly curved concave curve R2 on the distal side and a larger concave curve R1 on the proximal side. For example, the proximal radius R1 may be about 0.0112 inches, while the distal radius R2 may be about 0.010 inches. Again, the difference between the two radii (R1, R2) depends on the number of cuts, the bending angle at the fully articulated position, and the size of the angled opening. The larger the angled opening 42a, the greater the difference between the two radii. The asymmetry of both the edge lengths and the radii is configured to align the opposing edges 43 when in the fully articulated configuration, thereby improving the rigidity of the assembly in the fully articulated configuration, as will be described in more detail in the modified drawings.

[0050] Each cutout 42 is defined with a maximum opening width D1 along side surface 35 in the least jointed orientation that can be a linear configuration. The rounded closed end 42b defines a maximum axial dimension D2. D2 may preferably be greater than D1. However, D2 is preferably less than 50% greater than D1 such that a plurality of cutouts 42 are arranged closely and continuously and the articulated curves are evenly distributed along the curvilinear length. As shown, D2 is approximately 30% greater than D1. For a shaft with an outer diameter of 0.20 inches, D2 can be approximately 0.052 inches, while D1 can be, for example, 0.04 inches.

[0051] Figure 3B shows a close-up of the contour of a single cutout 42 of the plurality of cutouts 42. Distal and proximal edges (43a, 43b) having different lengths define an offset X at the transition to their respective bulbous ends 42b. The offset X is defined by the number of cutouts 42 and the angled opening dimensions. The offset X can range from about 0.003 inches to 0.015 inches for a tube with a diameter of 0.15 - 0.26 inches of the surgical device. Additionally, as disclosed herein, the distal concave surface of the rounded end 42b defines a more tightly curved surface than the corresponding proximal concave surface. As shown in Figure 3C, when articulated to a fully articulated configuration where two opposing edges 43a and 43b rotate towards each other, this offset X is configured to align the edges 43a, 43b such that they are adjacent and aligned with each other over a longer circumferential length, or arc length. This forms a continuous smooth inner radial surface 35 when in a fully articulated configuration (best seen in Figures 3C and 3D). Having this aligned contact along the edges 43 improves the rigidity of the assembly in a fully articulated configuration.

[0052] As a method of comparison, FIG. 4 shows the resulting shape of a fully articulated configuration where the keyhole contour is symmetric and there is no offset X. In this embodiment, the articulation does not result in a smooth and continuous inner curved surface because it forms a stepped or stepped inner surface of 35T. By omitting or reducing this step formation 35T, the torsional stiffness of the device when in a fully articulated configuration is increased. This can be best explained by looking at the comparison of the cross-sectional views shown in FIGS. 5A and 5B. Shown in FIG. 5A are two edges 43a, 43b (proximal and distal exemplary cutouts) of the asymmetric cutout 42 (see FIG. 3C) as disclosed herein. The bulbous portion 42b is removed to simplify the figure. FIG. 5A shows that when rotated to a fully articulated position such that the two edges 43a 43b are directly opposed, the two edges 43a and 43b are aligned with each other. FIG. 5B shows two edges of a symmetric cutout rotated to a fully articulated position in a stepped shape as shown in FIG. 4. While in the contour, as shown in FIG. 4, the length of the offset (stepped shape) may appear to be the same as Y. However, when viewed as the cross-section of FIG. 5B, it can be seen that the arc length of the contact between the two edges is significantly different between the two figures (FIGS. 5A and 5B). In FIG. 5A where the two edges 43 of the asymmetric cutout 42 are in a fully articulated configuration, the dimension Y represents the length of the edge 43a that is not in direct contact with the edge 43b. Compare this to the figure of FIG. 5B which represents two circumferential edges of an exemplary cutout of a symmetric keyhole contour as shown in FIG. 4. As shown, the arc length Z represents the arc length of the misaligned edge contact for the symmetric cutout. The length Z is considerably longer than the length Y. The contour of the asymmetric cutout 42 is configured to allow a longer arc length of contact of the direct edges 43 of each cutout 42. By utilizing this edge contact, the articulated shaft can achieve equivalent torsional stiffness when fully bent relative to the torsional stiffness of the fixed wand.

[0053] Another important characteristic shown in FIG. 3A is the gradual decrease in the width of the shaft's spine from the most proximal cut to the most distal cut. As best seen in FIG. 3A, the spine 46 of the outer shaft 34 tapers to a thickness T defined by the overall length of each of the keyhole cutouts 42. The spine 46 gets thicker as the spine extends proximally. T2 is greater than T1. This allows the stress to be more evenly distributed across each of the cuts 42, and the shaft 34 can return straight to its original shape instead of forming a twist along the spine. This is important to allow the shaft to slide back out of a 5.0 mm cannula after use. The number of cutouts is also refined to distribute stress, but also maintain a tight bend radius compatible with human anatomy. A range of 2 to 10 cutouts is envisioned by the inventors. More delicate and slender instruments may have more cutouts, each with a smaller angular opening θ, to better distribute stress and reduce fatigue along the tube spine.

[0054] Furthermore, the angles (θ) of each cutout 42 may differ from each other. In some examples, stress concentrations may exist at the most proximal and most distal cutouts. Thus, the angles (θ) are such that the most proximal and most distal cutouts 42 may be smaller than the intermediate cutouts 42. The bending angles at these most proximal and most distal cutouts 42 decrease, and the central cutout widens in width to maintain the same overall bending angle of the shaft when fully articulated. Additionally, it may also be useful to decrease the angle (θ) of the most distal cutout 42, because it may be difficult to fully close due to its proximity to the weld point 62. To maximize its torsional stiffness, all of the cutouts need to fully close when fully articulated, such that it preferably has an edge on an edge, or in most cases, metal on metal contact. Thus, the plurality of cutouts are configured for a particular target bending angle of the fully articulated portion for maximum stiffness and torsional resistance. For example, these shapes were developed for shafts having a maximum angle between 30 degrees and 70 degrees. A shaft of 30 - 40 degrees may mimic a fixed angle device as described herein. A shaft of 70 degrees may be used as a continuous articulated device, i.e., the surgeon may frequently change the degree of articulation during use.

[0055] Returning to FIGS. 2 and 6, the inner shaft 32 is shown, with the outer shaft 34 removed from FIG. 6 for clarity of illustration. The inner shaft 32 includes a cutout 40 having an opening portion 40a that may have two parallel edges defining an opening of uniform width along the length to the rounded slot 40b. The rounded slot 40b may also include a linear surface 40c that may be parallel to the shaft longitudinal axis L-L. These slots 40b create two points of stress concentration at each cut 40 such that the stress caused by extending the inner shaft spreads over a multiple number of locations. The stress distribution of the inner shaft 32 is important because it is subject to more fatigue by being stretched when the outer shaft is bent. The cutout 40 of the inner shaft is symmetric about the longitudinal axis of each cut L c and may be. However, the most distal inner cut 40 may be asymmetric about the longitudinal axis L that extends further distally than proximally along the shaft longitudinal axis L c .

[0056] In some embodiments, the articulatable portion 8 may also include a coiled or slotted liner 850 sandwiched between the outer sheath 120 and the outer shaft 834, at least as shown in FIGS. 8 - 10C. The slotted liner 850 may limit the movement of the outer sheath 120 of the articulation device between the openings of the articulatable portion 8 and may thus be applicable to any articulating shaft having a cutout that also requires an outer flexible sheath as part of its construction.

[0057] FIG. 8 shows the distal portion of the outer tube 834 that includes the cutout 842. The outer tube 834 may be similar to the outer tube 34. The cutout 842 may be similar to the cutout 42. For clarity of understanding the liner 850, the sheath 120 is not present in FIG. 8. The sheath 120 is shown coaxially covering the liner 850. The liner 850 may extend over and along the outer shaft 834. The liner 850 may extend beyond the most proximal and most distal cutouts 842 and may define a flexible sleeve. The liner 850 may be fixedly coupled to the tubular member 834, for example, via an adhesive. However, since the liner 850 is preferably flexible to avoid interfering with the articulation of the shaft 834, small individual fixation areas are desirable rather than on the large surface of the liner 850 that could unduly add rigidity. For example, the liner 850 may be fixedly coupled, for example, in 1 to 3 spots around the liner surface or along a narrow circumferential line 855. In some embodiments, the liner 850 may be restricted from sliding along the shaft 834 by the assembly of only the sheath 120. The liner 850 may be fixedly coupled at only one end to allow the liner 850 to move axially during articulation of the instrument.

[0058] As described above, the sheath 120 on the articulatable portion 8 may be required as part of the functionality of the instrument, for example, to electrically isolate the shaft and / or limit debris and to penetrate through the cutout 842. However, the sheath 120 is preferably flexible so as to minimally affect articulation, and this flexibility may essentially enable movement of the sheath 120 to the cutout 842. Thus, the inventors developed a liner 850 for coaxial placement between the shaft 842 and the sheath 120 to limit movement of the sheath. The liner is a thin sleeve that avoids adding bulk or diameter to the device and has a stiffness configured to withstand movement to the cutout 842 of both itself and the sheath 120. However, making the liner stiffer to avoid movement may impede articulation as disclosed herein. Thus, the liner 850 includes discontinuities in the form of slots or cuts through the thickness of the liner, which are configured to increase the flexibility of the liner during articulation. The slots or cuts may be oriented to maintain a barrier to movement of the sheath to the cutout 842. The slots or cuts may be oriented at a non-zero angle with respect to both the longitudinal and transverse axes of the liner 850. In some embodiments, the sheath may be heat shrinkable, and thus the process of shrinking the sheath may naturally form the sheath 120 to its shape and may cut along the liner 850.

[0059] As shown in FIGS. 9A and 9B showing only the liner, the slot or cut can be a continuous helical cut 860 along the length of the liner 850 to increase flexibility. The sheath 120 preferably does not include these discontinuities as it would change the rationale of the sheath 120. For example, a sheath 120 with a cut is no longer an effective electrical isolator or fluid barrier. Thus, the liner 850 can define a thin flexible tube section, which can be made of nylon and include a helical or spiral cut 860. The liner 850 preferably covers the articulable portion 8, including the most proximal and most distal cutouts 842. The helical cut 860 may extend along the inner portion of the liner 850, with no cuts at both ends (850a, 850b) of the liner, thereby eliminating discontinuities at the tubular ends. These cut-free ends (850a, 850b) may have an axial length of about 0.1 - 0.3 inches. The liner 850 can cover only the articulable portion 8 and be coaxial therewith, and may be completely separated from the handle of the instrument. Since the liner 850 does not provide a force transmission means, the articulation of the device cannot be directly controlled thereby. The liner 850 acts as a partial barrier and is configured to at least partially block the entry of the sheath 120 into the articulable portion 8. The liner 850 may be disposed over a plurality of axially spaced cutouts 842 of the articulable portion 8. In a straight (non-articulable) configuration, the liner 850 can expand axially (as shown by the arrow in FIG. 9B) to create an axial gap 845 along the liner 850 in an axially extended form 850'. The ends 850a and 850b may then be fixed to the shaft 834 in this extended form 850'. The inventors have found that by forming these gaps 845, the flexibility of the liner 850 during articulation is increased. In an alternative embodiment, the gap 845 can be formed by removing material. In other words, two parallel cuts are formed spirally, thereby removing material equal to the width of the gap 845.The width and spacing of the spiral cut 860 can be configured to minimize the articulation operation of the device while reducing the exposure of the insulation sheath 120 to the radial cutout 842. More specifically, the spiral cut and gap 845 are configured to add flexibility to the liner 850, thereby reducing any resistance that this liner can add to the shaft articulation. In a further alternative embodiment, while in a linear non-articulated position, the spiral cut may spread and not form a gap 845. This may depend on the flexibility of the liner 850 material and the angular offset value of the articulation. For example, the smaller the angular offset at which the device is configured to articulate, the less flexible the liner 850 may need to be, and an axial gap may not be required. Thus, the gap 845 may be negligible until the shaft is in an articulated state, and the gap 845 may expand or contract accordingly. A larger axial gap 845 along the spiral cut can reduce the resistance to shaft articulation, but can also increase the exposure of the radial cutout 842 to the sheath 120, risking interference between the sheath 120 and the cutout 842.

[0060] To reduce exposure to the cutout 842, the inventors envision ranges of the angle, width, and spacing of the spiral cut 860 such that the spiral cut 860 can be defined by an axial distance along the liner 850 each time the spiral cut 860 makes a full rotation, preferably as shown as distance W in FIGS. 9B and 9C. More specifically, the spiral cut 860 can preferably be defined in that substantially all of each rotation of the spiral cut 860 around the length of the liner 850 occurs within respective distances along the length of the articulable portion 8 of at least the axial distance between two consecutive cutouts 842. More preferably, the spiral cut can be defined in that substantially all of each rotation of the spiral around the length of the liner 850 occurs within respective distances along the length of the articulable portion 8 of at least the axial distance (Z) between two consecutive cuts 842. The distance W is preferably greater than the distance Z.

[0061] FIG. 9C schematically shows an exemplary embodiment of an articulated shaft 834 having a liner 850 and a sheath 120 in a state where the shaft 834 is in a straight configuration. The tubular shaft 834 includes a plurality of exemplary axially spaced cutouts 842 that are at least partially covered by the liner 850. The liner 850 may be a thin flexible sleeve or tube having angled or spiral cuts 860 that extend along the length of the liner 850. The angled cut, or spiral cut 860, may extend along an axial length that is approximately equal to the axial length of the articulated portion 8. The spiral cut 860 may flare axially to form a small gap 845 and increase the flexibility of the liner 850. The spiral cut 852 may define the axial length of each spiral "W". The spiral cut 852 may be formed at an angle β with respect to the longitudinal axis L, where the angle β is in the range of 90 to 180 degrees, more preferably in the range of 100 to 170 degrees. In the cross-section of this embodiment, the spiral cut 860 is defined such that substantially every rotation of the spiral around the length of the liner 850, shown as Z on FIG. 9C, occurs within a respective distance that is greater than the axial distance between a first radially adjacent cutout and a radially adjacent cutout along the length of the tubular shaft 834.

[0062] Advantageously, this liner 250 can reduce the movement of a sheath within an electrosurgical instrument in which electrical energy is insulated by a sheath along a portion of the instrument. The instrument may be monopolar or bipolar and may be used to treat tissue using energy such as cutting, coagulation, ablation, and heating. Exemplary electrosurgical instruments may include a coblation wand such as the wand described in U.S. Patent No. 10,420,601, which is hereby incorporated by reference in its entirety and is generally owned. FIG. 10A shows an elevation view of an exemplary wand, more specifically, an exemplary electrosurgical wand 302, according to an exemplary system. In particular, the wand 302 includes an elongated shaft 306 that may be similar to the shaft 34 or shaft 834 disclosed in previous figures. The shaft 306 may define a tubular member for actually receiving an electric wire and a fluid suction or fluid delivery tube, and may include a series of radial cutouts 304 that define an articulable portion 307 of the shaft 306. The wand 302 may also include a handle 310 coupled to the proximal end of the elongated shaft 306, and the handle 310 includes an actuation control 330 for articulating the articulable portion 307. Also visible in FIG. 10A is a flexible tubular member 316 extending from the handle 310 and a multi-conductor cable 312. The wand 302 may include an active electrode 305 disposed on the distal end 308 of the elongated shaft 306. The active electrode 305 may be coupled to an active or passive control network within a controller (not shown) by one or more insulated electrical connectors (not shown) of the multi-conductor cable 112. The active electrode 305 is separated from the shaft 306 by an electrode support member 300 coupled to the distal end of the elongated shaft 306. The active electrode 305 may be electrically separated from a common electrode or return electrode disposed on the shaft proximal to the active electrode 302 within 1 millimeter (mm) to 25 mm of the distal tip in some exemplary systems.The return electrode 311 may define the distal end of the shaft tubular member 306 and may have an outer peripheral portion that is at least partially defined by the coaxial sheath 120, which outer peripheral portion ends with an "A" and thereby defines an exposed conductive portion of the tubular member sized and configured to operate as the return electrode 311. The support member 300 is positioned distally of the return electrode 311 and may be made of an electrically insulating material such as epoxy, plastic, ceramic, silicone, glass, etc. The support member 300 extends from the elongated shaft 306 (typically about 1 to 20 mm) and provides support for the active electrode 305. It should be noted for clarity of explanation that FIG. 10A does not show the liner 850 as it is covered by the sheath 120 in this figure. Additionally, for clarity of the description, FIGS. 10A - 10C do not show the mechanism for articulating the articulatable portion 307 so as not to unduly complicate the figure. As an exemplary mechanism (not shown), an inner shaft or pull rod may extend along the shaft 306, be coaxially disposed with the tubular member, and be axially fixed to an attachment point located distally from the articulatable portion 307. The proximal portion of the inner shaft is displaceable along the longitudinal axis of the shaft 306 and can articulate the articulatable portion 307 from a non-articulated configuration (or a less articulated configuration) to an articulated configuration. The inner shaft may be an inner tubular member and may include a plurality of axially spaced radial cutouts along the articulatable portion 307, which may be on the opposite side of the radial cutout 304 from that similar to the embodiments disclosed herein, to facilitate articulation.

[0063] FIG. 10B shows the distal end 308 of the wand 302 according to an exemplary embodiment, with the sheath 120 and the liner 850 partially removed. In particular, the wand 302 may include a fluid conduit, such as a suction lumen 318, that extends through the spacer 300 and the electrode 305 along the elongated shaft 306. In some embodiments, the inner diameter of the tubular member 306 may define the suction lumen 318. As shown, a separate tube 319 within the elongated shaft 306 may define a portion of the suction lumen 318. The suction lumen 318 may provide a conduit for suctioning excess fluid, bubbles, tissue fragments, and / or ablation products from a target site proximate the active electrode 302. In embodiments where the shaft 306 provides a portion of the suction lumen conduit, the sheath 120 may prevent inadvertent aspiration through the cutouts 304, 842, or 42. The suction lumen 318 extends into the handle 310 and fluidly couples to a flexible tubular member 316 that may be coupled to a peristaltic pump (not shown).

[0064] FIG. 10C shows a perspective view of the distal end 308 of the wand 302 according to an exemplary system. In particular, the active electrode 305 may be an active screen electrode. The screen electrode 305 may include a conductive material such as, for example, tungsten, titanium, molybdenum, platinum, etc. The screen electrode 305 may have a diameter in the range of about 0.5 - 8 mm, in some cases about 1 - 4 mm, and about 0.05 - about 2.5 mm, in some cases about 0.1 - 1 mm. The screen electrode 305 may include at least one opening 312 configured to rest over the distal opening 388 of the suction lumen 318. The opening 312 is designed to allow passage of aspirated excess fluid, bubbles, and ablation site gas and is large enough to allow ablated tissue fragments to pass into the suction lumen 318.

[0065] FIG. 10C represents a cross-section referenced in FIG. 10C. A plurality of tubular elements or shafts may be coaxially arranged along the articulable portion 307. As shown, the outermost sheath 120 may define the outer surface of the device 302 and may be configured to electrically isolate portions of the device. The sheath 120 may be coaxial with the liner 850 and may be wrapped around the liner 850 and may thermally shrink around the liner 850 to be partially formed into a liner configuration. The liner 850 may include a cut 860 configured to inhibit movement of the sheath 120 into the shaft cutout as described above. The liner is coaxially sandwiched between the sheath 120 and the articulated shaft 306. The liner 850 may be fixedly coupled to the shaft 306 at individual locations, for example, using an adhesive. The shaft 306 may include an articulated cutout 42 / 304 (shown in other figures). The inner lumen of the shaft 306 may be coupled to an inner rod or tube such as the tube 32 disclosed herein, and displacement of the inner rod or tube 32 may actuate the articulable portion 307. The inner tube or rod 32 may also include a cutout (not shown in this figure). An electrical cable (not shown) may extend along the shaft 306 to provide energy to the electrodes. A flexible tube 319 may extend along the shaft such that fluid flows through it. In some embodiments, the inner lumen of the inner tube 32 or the inner lumen of the shaft 306 may form part of the boundary of the fluid flow conduit.

[0066] The foregoing considerations are meant to be illustrative of the principles of the invention and examples of various embodiments. Numerous variations and modifications will become apparent to those skilled in the art upon a full understanding of the above disclosure. The following claims are intended to be construed to embrace all such variations and modifications.

[0067] Although only some embodiments of the present invention have been described, it should be understood that the present invention can be embodied in many other specific forms without departing from the spirit or scope of the present invention. Accordingly, this example is to be considered as illustrative and not restrictive, and the present invention is not limited to the details given herein but may be modified within the scope of the appended claims.

Claims

1. A surgical instrument, comprising a handle, an elongate shaft assembly extending distally from the handle and defining a longitudinal axis, the elongate shaft assembly being configured to articulate between a fully bent configuration and a configuration that is relatively unbent compared to the fully bent configuration, the elongate shaft assembly comprising a tubular member including a flexible portion having a first preferred bending direction, and an elongate member disposed coaxially with the tubular member within the tubular member and directly coupled to the tubular member at a distal location of the flexible portion, the flexible portion being defined by a plurality of cutouts that communicate with a space within the tubular member in which the elongate member is disposed, each cutout defining a cutout longitudinal axis, each cutout including a tapered portion defined by a proximal linear edge and a distal linear edge, at least two adjacent ones of the plurality of cutouts each defining an asymmetrical shape about the cutout longitudinal axis, the asymmetrical shape being configured such that when the flexible portion is in the fully bent configuration, a corresponding proximal linear edge and distal linear edge are aligned with each other.

2. The surgical instrument according to claim 1, wherein each of the cutouts has a keyhole shape having a bulbous closed end, the bulbous closed end being asymmetrical about the cutout longitudinal axis.

3. The surgical instrument according to claim 1, wherein each of the cutouts has a keyhole shape including a bulbous closed end, the bulbous closed end defining a proximal concave surface and a distal concave surface that are continuous with each other, the distal concave surface defining a smaller radius of curvature than the proximal concave surface.

4. The surgical instrument according to claim 3, wherein a maximum axial length of the bulbous closed end portion is less than 50% greater than a maximum axial length of the tapered portion when the surgical instrument is in a non-relatively bent configuration.

5. The surgical instrument according to claim 1, wherein in the fully bent configuration, corresponding proximal linear edges and distal linear edges of each of the plurality of cutouts are aligned with each other to form a continuous inwardly curved shaft surface without terracing.

6. The surgical instrument according to claim 1, wherein the asymmetric shape of the cutout is configured to rotate the distal linear edge toward the proximal linear edge so as to be aligned when the elongated shaft assembly is in the fully bent configuration.

7. The surgical instrument according to claim 3, wherein each of the plurality of cutouts defines an angular opening when the elongated shaft assembly is in a non-relatively bent configuration, and the most distal cutout of the plurality of cutouts has an angular opening smaller than all of the remaining plurality of radial cutouts.

8. A surgical instrument, a handle, an elongated shaft assembly extending distally from the handle, the elongated shaft assembly comprising: a tubular member including an articulable portion defined by a plurality of cutouts; an elongated member disposed coaxially with the tubular member along the tubular member and coupled to the tubular member at a position distal to the articulable portion, the elongated member being configured to bend the articulable portion to axially offset the distal end of the tubular member with respect to the proximal end of the elongated shaft; and an elongated shaft assembly comprising: The plurality of cutouts define a longitudinal axis that traverses the shaft longitudinal axis, the plurality of cutouts communicate with a space within the tubular member in which the elongated member is disposed, and at least two adjacent ones of the plurality of cutouts each define an asymmetric shape about a cutout longitudinal axis, the asymmetric shape being configured such that when the distal end is bent at the maximum offset angle, the proximal circumferential edge and the distal circumferential edge of each cutout are aligned with each other. Surgical instrument. Claim 9 The plurality of cutouts define a keyhole shape having a bulbous closed end, the bulbous closed end defining a concave proximal surface and a concave distal surface that faces the concave proximal surface and is different from the concave proximal surface. The surgical instrument according to claim 8. Claim 10 The surgical instrument according to claim 9, wherein the concave proximal surface defines a radius of curvature larger than that of the concave distal surface. Claim 11 The surgical instrument according to claim 9, wherein the asymmetric shape is configured to form a continuous and unbroken curve along the articulatable portion when the distal end is bent at the maximum offset angle. Claim 12 Each of the plurality of cutouts defines an angular opening, and when the shaft is in a relatively unbent configuration, the angular opening of the most distal cutout of the plurality of cutouts has an angular opening smaller than that of all the remaining cutouts. The surgical instrument according to claim 9. Claim 13 The elongated shaft assembly A sheath that is coaxial with the tubular member and covers the tubular member including covering the articulatable portion. A liner disposed between the sheath and the tubular member along the articulatable portion, the liner including at least one discontinuous portion through the thickness of the liner, the articulatable portion being configured to allow articulation while simultaneously blocking movement of the sheath to the radial cutout thereof. The surgical instrument according to any one of claims 1 to 12, comprising.

14. The surgical instrument according to claim 13, wherein the discontinuous portion includes a helical cut around and along a portion of the liner.

15. The surgical instrument according to claim 13, wherein the discontinuous portion comprises a helical cut having an axial gap length, the axial gap length being configured to increase the flexibility of the liner while simultaneously blocking movement of the sheath to the radial cutout thereof.

16. The surgical instrument according to claim 15, wherein the axial gap length is defined by a single helical cut extending axially.

17. The surgical instrument according to claim 13, wherein the tubular member is conductive and the sheath is an electrical insulator configured to limit the exposed conductive outer surface of the tubular member.

18. The surgical instrument according to claim 13, wherein the liner is a nylon sleeve.

19. The surgical instrument according to claim 14, wherein substantially each rotation of the helical cut occurs within a respective distance along the length of at least two of the articulatable portions of the plurality of radial cutouts.

20. The surgical instrument according to claim 14, wherein substantially each rotation of the helical cut occurs within a respective distance along the axial length of the articulatable portion so as to cover at least three of the plurality of radial cutouts.

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