Patent Description:
Remotely controlled surgical instruments, including teleoperated surgical instruments, are often used in minimally invasive medical procedures. During medical procedures, surgical instruments may be articulated in one or more directions. For instance, the surgical instrument may be actuated by a transmission mechanism at a proximal end of the surgical instrument shaft to orient and position an end effector located at a distal end of the surgical instrument in a desired location. The surgical instrument may further include a wrist, such as a jointed, articulatable structure, that the end effector is connected to so that the end effector may be positioned relative to the shaft. The surgical instrument may further include one or more end effector actuation elements that pass through the surgical instrument, including the wrist, to actuate the end effector. Articulating (bending) the wrist may result in bending of the end effector actuation element(s), which may cause a change in the length of the end effector actuation element(s). Such a change in length can result in unintended motions of the end effector. In view of this, it may be desirable to provide a surgical instrument that includes one or more end effector actuation elements configured to substantially conserve the length of the actuation elements when a wrist of the instrument is articulated. <CIT> discloses a medical instrument assembly comprising a shaft, a tool carried by the distal end of the shaft for performing a medical procedure on a patient, an end effector, a threaded housing in which the threaded distal shaft end is configured for being screwed, and a first threaded piece disposed in the threaded housing and configured for being moved to actuate the end effector. The assembly further comprises an actuation element extending within the shaft. The actuation element includes a second threaded piece that distally extends from the threaded distal shaft end. The second threaded piece is configured for being screwed to the first threaded piece. A robotic system comprises the assembly, a user interface configured for generating command(s), a drive unit coupled to the actuating element, and an electric controller configured, in response to the command(s), for directing the drive unit to move the actuating element to actuate the tool. <CIT> discloses a surgical end effector includes a clevis and two jaws pivotally coupled to the clevis. A wire is coupled to each jaw and extended through a guide way in the other jaw and through an end of the clevis. The jaws may be opened and closed by pushing and pulling on the two cables. Pulling on each wire creates a closing force in both jaws. A rocking pin may be pivotally supported by the clevis and pivotally coupled to the jaws to constrain the jaws to have opposite motions. The clevis may be coupled to an elongate shaft and the wires extended through the shaft to provide an endoscopic instrument. A wire guide may support the wires in the shaft such that they are able to transmit a compressive force without buckling. <CIT> discloses a surgical manipulator including an internal working end having an internal joint, and an external control interface linked to the internal working end for controlling the internal working end. The external control interface includes at least one lever defining a grip volume for a surgeon's hand when gripping and operating the at least one lever, and an external joint linked to the internal joint for controlling the internal joint. The external joint is positioned substantially within the grip volume. <CIT> discloses a medical implant deployment tool and deployment method. One aspect provides an implant system including an implant adapted for endovascular delivery and deployment; and a deployment tool adapted to deploy the implant, with the deployment tool having an actuation controller; a plurality of actuation elements adapted to apply forces to one or more implant deployment mechanisms and each adapted to extend along an actuation element path within a patient's vasculature; and an actuation element compensation mechanism adapted to compensate for differences in length between the actuation element paths. Another aspect provides a method of deploying an implant including the steps of endovascularly delivering an implant and implant deployment mechanisms to an implant site and applying an actuation force to the implant deployment mechanisms through actuation elements extending through the patient's vasculature while compensating for differences in length between actuation element path lengths to deploy the implant.

Exemplary embodiments of the present disclosure may solve one or more of the above-mentioned problems and/or may demonstrate one or more of the above-mentioned desirable features. Other features and/or advantages may become apparent from the description that follows.

The present invention is defined by independent claim <NUM>. Further aspects of the present invention are set out in the dependent claims.

In accordance with an example, a support structure for an actuation element of a surgical instrument may comprise at least one passage defining a twisted path about a longitudinal axis of the support structure. The passage may have an angular extent of less than <NUM> degrees from a first end of the passage to a second end of the passage.

In accordance with an example, a method of configuring a surgical instrument wrist may comprise extending an actuation element along the wrist so the actuation element follows a twisted path along at least a portion of the wrist. The twisted path may have an angular extent of less than <NUM> degrees.

Additional objects, features, and/or advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present disclosure and/or claims. At least some of these objects and advantages may be realized and attained by the elements and combinations particularly pointed out in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the claims.

The present disclosure can be understood from the following detailed description, either alone or together with the accompanying drawings. The drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more exemplary embodiments of the present teachings and together with the description serve to explain certain principles and operation.

This description and the accompanying drawings that illustrate exemplary embodiments should not be taken as limiting. In some instances, well-known structures and techniques have not been shown or described in detail so as not to obscure the disclosure. Furthermore, elements and their associated features that are described in detail with reference to one embodiment may, whenever practical, be included in other embodiments in which they are not specifically shown or described. For example, if an element is described in detail with reference to one embodiment and is not described with reference to a second embodiment, the element may nevertheless be claimed as included in the second embodiment.

For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages, or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term "about," to the extent they are not already so modified. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the," and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term "include" and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

Further, this description's terminology is not intended to limit the disclosure or claims. For example, spatially relative terms-such as "beneath", "below", "lower", "above", "upper", "proximal", "distal", and the like-may be used to describe one element's or feature's relationship to another element or feature as illustrated in the figures. These spatially relative terms are intended to encompass different positions (i.e., locations) and orientations (i.e., rotational placements) of a device in use or operation in addition to the position and orientation shown in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be "above" or "over" the other elements or features. Thus, the exemplary term "below" can encompass both positions and orientations of above and below. A device may be otherwise oriented (rotated <NUM> degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The present invention concerns surgical instruments for teleoperated surgical systems that utilize an actuation element, with at least a portion of the actuation element being arranged along a twisted path. The actuation element may be used to actuate an end effector, to articulate a wrist, or to actuate another component of an instrument. Further, the exemplary embodiments may be applied to any actuation element offset from a central longitudinal axis (neutral axis) of a surgical instrument. According to the invention, the twisted path has an angular extent less than <NUM> degrees, relative to a centerline of the wrist, along an entire length of the wrist. According to an exemplary embodiment, at least a portion of an actuation element may be arranged along a twisted path so that the length of the actuation element is conserved at each joint of the wrist as the wrist actuates or bends. By conserving the length of the actuation element, changes in length of an actuation element, which might interfere with the actuation functions of the actuation element, that may otherwise occur during bending of a wrist may be minimized or eliminated. According to an exemplary embodiment, an actuation element may be arranged along a twisted path so that the length of the actuation element is conserved at an individual joint of a wrist but not conserved at another individual joint of the wrist, with the total twisted path of the actuation element being a length conservative structure.

The present disclosure further contemplates an actuation element support. An actuation element support may be used to shape at least a portion of an actuation element into a desired shape, such as along a twisted path, to conserve length of the actuation element and/or to increase the buckling strength of the actuation element. According to an exemplary embodiment, an actuation element support may be a single piece member that includes at least one lumen, wherein at least a portion of the lumen has a twisted shape. According to an exemplary embodiment, an actuation element support may include at least one rigid portion. An actuation element support may include, for example, a plurality of coaxial tubes, according to an exemplary embodiment. According to an exemplary embodiment, an actuation element support may comprise a tube with one or more areas of material weakness, such as cut-out grooves, to provide flexibility to the support. An actuation element support may include a hollow structure, such as a flexible shaft, useful for both pushing and pulling motions, according to an exemplary embodiment. A flexible shaft may be, for example, a wound spring connected to filaments. According to another exemplary embodiment, a flexible shaft may include multiple layers of wound filaments connected together.

Turning to <FIG>, an example of a teleoperated surgical system <NUM> is shown that can employ surgical instruments in accordance with embodiments described herein. System <NUM>, which may, for example, be a da Vinci® Surgical System available from Intuitive Surgical, Inc. , includes a patient side cart <NUM> having multiple surgical instruments <NUM>, each of which is mounted in a docking port on an arm <NUM>. Instruments <NUM> can be interchangeable, so that the instruments <NUM> mounted on arms <NUM> can be selected for a particular medical procedure or changed during a medical procedure to provide the clinical functions needed. As is well known in the art, surgical instruments <NUM> can implement many functions including, but not limited to, for example, forceps or graspers, needle drivers, scalpels, scissors, cauterizing tools, and staplers.

Each instrument <NUM> generally includes a transmission or backend mechanism <NUM>, a main shaft <NUM> extending from the transmission mechanism <NUM>, an optional wrist (not shown in <FIG>) at the distal end of main shaft <NUM>, and an end effector <NUM> extending from wrist or directly from the shaft <NUM>. For instance, <FIG> illustrates one exemplary embodiment of a distal end of a surgical instrument that includes, among other things, a shaft <NUM>, a wrist <NUM> at a distal end of shaft <NUM>, and an end effector <NUM> extending from wrist <NUM>. Actuation elements <NUM>, such as, for example, tendons or rods, may extend through shaft <NUM> to wrist <NUM> and/or to end effector <NUM>. As those of ordinary skill in the art are familiar with, actuation elements may be configured as pull/pull or push/pull actuation elements. Exemplary embodiments of pull/pull and push/pull actuation devices are described in <CIT>. Thus, actuation elements <NUM> may be used to actuate wrist <NUM> and/or end effector <NUM>. Thus, with reference to <FIG>, actuation elements may extend from a transmission mechanism <NUM>, which may be connected to a patient side manipulator <NUM>. Transmission mechanism <NUM> typically provides a mechanical coupling of the actuation elements to drive motors in patient side cart <NUM>. For instance, transmission mechanisms <NUM> may be configured to connect to patient side manipulators <NUM> of arms <NUM> of the patient side cart <NUM>. As a result, patient side manipulators <NUM> and transmission mechanisms <NUM> may be used to apply a force to actuation elements <NUM> to actuate wrist <NUM> and/or end effector <NUM>. Further, with reference again to <FIG>, electrical conductors (not shown in <FIG>) may also extend through shaft <NUM> and wrist <NUM> to end effector <NUM>.

System <NUM> can thus control movement and forces along the actuation elements as needed to move or position a wrist and operate end effector <NUM>. An arm <NUM> of patient side cart <NUM> can be used to insert the end of a surgical instrument <NUM> through a cannula in small incisions in a patient undergoing a medical procedure and to operate a wrist of instrument <NUM> and/or end effector <NUM> at a worksite inside the patient.

A camera instrument <NUM> can similarly be mounted on an arm of cart <NUM> and optionally also have a wrist that system <NUM> operates to position a distal end of camera system <NUM> for viewing of a work site and the operation of surgical instruments <NUM> within a patient. The views from camera system <NUM>, which may be stereoscopic or three-dimensional, can be viewed at a control console (not shown) and images may be displayed on a monitor <NUM>. A processing system of system <NUM> can thus provide a user interface enabling a doctor or other medical personnel to see and manipulate the camera system <NUM> and instruments <NUM>. For example, as with surgical instruments <NUM>, an arm <NUM> can be used to insert the end of a camera instrument <NUM> through a cannula in small incisions in a patient undergoing a medical procedure and to operate wrist and/or end effector <NUM> at a worksite inside the patient.

The diameter or diameters of main shaft <NUM>, wrist, and end effector <NUM> for surgical instrument <NUM> and the diameter of camera instrument <NUM> are generally selected according to the size of the cannula with which the instrument will be used. In an exemplary embodiment, a diameter of camera instrument <NUM> and a diameter of wrist and main shaft <NUM> may range from about <NUM> to about <NUM>. For example, the diameter may be about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> to match the sizes of some existing cannula systems.

As illustrated in the schematic view of <FIG>, the teleoperated surgical system <NUM> may further include a surgeon console <NUM> and an auxiliary control/vision cart <NUM>. In general, the surgeon console <NUM> receives inputs from a user, e.g., a surgeon, by various input devices, including but not limited to, gripping mechanisms <NUM> and foot pedals <NUM>, and serves as a master controller to which the instruments <NUM> mounted at the patient side cart <NUM> are responsive to implement the desired motions of the surgical instrument(s) <NUM>, and accordingly perform the desired surgical procedure. For example, while not being limited thereto, the gripping mechanisms <NUM> may act as "master" devices that may control the surgical instruments <NUM> and/or camera instrument <NUM>, which may act as the corresponding "slave" devices at the arms <NUM>. For instance, gripping mechanisms <NUM> may control an end effector <NUM> and/or wrist of the surgical instrument <NUM>, as those having ordinary skill in the art are familiar with. Further, while not being limited thereto, the foot pedals <NUM> may be depressed to provide, for example, monopolar or bipolar electrosurgical energy, or to activate a variety of other functions (e.g., suction, irrigation, and/or various other flux delivery modes) of the instruments <NUM>. In other words, based on the commands provided to input devices at, for example, the surgeon console <NUM>, the patient side cart <NUM> can position and actuate the instruments <NUM>, <NUM> to perform a desired medical procedure via the patient side manipulators <NUM> at the arms <NUM>. Thus, the instruments <NUM>, <NUM> of patient side cart <NUM> may be remotely teleoperated according to commands inputed by a user at the surgeon console <NUM>. Surgeon console <NUM> may further include a display to allow a surgeon to view a three-dimensional image of the surgical site, for example, during the surgical procedure, e.g., via the camera instrument <NUM> at the patient side cart <NUM>.

In non-limiting exemplary embodiments of the teleoperated surgical system, the control/vision cart <NUM> includes "core" processing equipment, such as core processor <NUM>, and/or other auxiliary processing equipment, which may be incorporated into or physically supported at the control/vision cart <NUM>. The control/vision cart <NUM> may also include other controls for operating the surgical system. In an exemplary embodiment, signal(s) or input(s) transmitted from surgeon console <NUM> may be transmitted to one or more processors at control/vision cart <NUM>, which may interpret the input(s) and generate command(s) or output(s) to be transmitted to the patient side cart <NUM> to cause manipulation of one or more of surgical instruments <NUM>, <NUM> and/or arms <NUM> to which the surgical instruments <NUM>, <NUM> are coupled at the patient side cart <NUM>. It is noted that the system components in <FIG> are not shown in any particular positioning and can be arranged as desired, with the patient side cart <NUM> being disposed relative to the patient so as to affect surgery on the patient.

A surgical instrument may have one or more degrees of freedom, permitting the instrument to bend in one or more directions. For instance, the wrist may provide articulation to permit bending in one or more directions, such as in arbitrary pitch and yaw directions that are substantially orthogonal to one another. An instrument may include other joints that permit bending, such as a joggle joint described in <CIT>, and U. Elements that pass through bent portions of an instrument, including actuation elements (e.g., tendons or rods) and electrical cables, such as for actuating a wrist or an end effector, are also bent.

Bending may have an effect upon actuation elements when the actuation elements pass through bent portions of a surgical instrument. Turning to <FIG>, a schematic perspective view is shown of a single flexible member <NUM> that can bend like a joint. A first actuation element <NUM> and a second actuation element <NUM> extending through member <NUM>, such as along a longitudinal axis <NUM> of member <NUM>. In the exemplary embodiment of <FIG>, wherein member <NUM> is in a straight (neutral) configuration, a bending axis <NUM> passes through each of first actuation element <NUM> and second actuation element <NUM>. As shown in <FIG>, when member <NUM> is bent around bending axis <NUM>, first and second actuation elements <NUM>, <NUM> bend as well. Because axis <NUM> passes through both of actuation elements <NUM>, <NUM>, there is no relative change in length between first actuation element <NUM> and second actuation element <NUM>. In other words, one of actuation elements <NUM>, <NUM> does not become substantially longer or substantially shorter than the other.

Turning again to <FIG>, a second bending axis <NUM> for member <NUM> passes between first actuation element <NUM> and second actuation element <NUM>. As a result, when member <NUM> is bent in the manner shown in <FIG> about bending axis <NUM>, first actuation element <NUM> is stretched relative to its neutral position, causing a positive change in its length, while second actuation element <NUM> is compressed relative to its neutral position, causing a negative change in its length. Therefore, bending member <NUM> relative to bending axis <NUM> can cause a change in the relative lengths of actuation elements <NUM>, <NUM>, with one actuation element becoming longer the other. Such a relative change in length can interfere with the function of actuation elements, such as to actuate an end effector. For instance, when actuation elements <NUM>, <NUM> are used to open and close an end effector by applying tension or compression to actuation elements <NUM>, <NUM>, a relative change in length between actuation elements <NUM>, <NUM> may create slack in one of the actuation elements <NUM>, <NUM>, diminishing the ability of the actuation element to transmit the desired tension or compression and cause a desired actuation of an end effector.

In view of these considerations, it may be desirable to design a joint of a surgical instrument so that a bend axis of the joint extends through an actuation element. For instance, a single actuation element may be provided to actuate an end effector, with the single actuation element extending along a center of a surgical instrument. In such a configuration, bending axes that are substantially orthogonal to one another, such as to provide two degrees of freedom for bending a surgical instrument, may pass through the center of the instrument and the actuation element. As a result, the length of the actuation element does not substantially change when the surgical instrument is bent around either bending axis. However, although this approach can be useful when a single actuation element is sufficient to control an end effector, a surgical instrument may include multiple actuation elements, such as to actuate different components of the instrument or to actuate an end effector or wrist that requires more than one actuation element.

<FIG> illustrates an example of a surgical instrument <NUM> that includes multiple actuation elements. In various exemplary embodiments, surgical instrument <NUM> may be a surgical instrument configured according to the exemplary embodiments described in U. No. <CIT>; U. No. <CIT>; and U. As illustrated, surgical instrument <NUM> includes a first component actuation element <NUM> that extends along a centerline <NUM> of surgical instrument <NUM>. First actuation element <NUM> may be configured, for example, to actuate a cutting blade <NUM> or other component by pushing or pulling cutting blade along centerline <NUM>.

Because first actuation element <NUM> is located along centerline <NUM>, both pitch and yaw bend axes <NUM>, <NUM> of instrument <NUM> pass through first actuation element <NUM>. As a result, first actuation element <NUM> does not substantially experience a change in length when surgical instrument <NUM> is bent relative to axis <NUM> or axis <NUM>. Surgical instrument <NUM> also includes other actuation elements, such as second and third end effector actuation elements <NUM>, <NUM> to actuate, for example, an end effector (not shown) of instrument <NUM>. The end effector may be, for example, forceps or graspers, needle drivers, scalpels, scissors, cauterizing tools, staplers, or other types of end effectors, for example, jawed end effectors, used in the art. According to an exemplary embodiment, actuation elements <NUM>, <NUM> may be pull/pull actuation elements that open and close an end effector by paying out one of actuation elements <NUM>, <NUM> and pulling the other of actuation elements <NUM>, <NUM>, as one of ordinary skill in the art is familiar with. Surgical instrument <NUM> may include additional lumens <NUM>, <NUM> for other components, such as, for example, additional actuation elements or flux conduits, such as conductors providing electrosurgical energy or other flux supplies to an end effector.

Because first actuation element <NUM> is present, actuation elements <NUM>, <NUM> cannot be located along centerline <NUM> and axis <NUM> does not pass through actuation elements <NUM>, <NUM>. Thus, when surgical instrument <NUM> is bent relative to axis <NUM>, a change in length may occur between actuation elements <NUM>, <NUM>. Due to these changes in length of actuation elements <NUM>, <NUM> during bending, greater mechanical complexity is required for instrument <NUM> to decouple actuation elements <NUM>, <NUM> from each other for actuation of an end effector.

In view of these considerations, the present disclosure contemplates surgical instruments having one or more actuation elements that do not substantially exhibit an overall change in length during bending, even when the actuation element position is offset from a bending axis. When an actuation element's overall change in length during bending is minimal, the mechanical complexity of an instrument including the actuation element may be reduced. In addition, by making an actuation element that does not substantially change its overall length due to bending (in other words, conserving the length of the actuation element), the actuation element may be decoupled from motion of a joint that the actuation element extends through. In other words, despite articulation of such joint(s), bending of the actuation element will not result in undesired or unintended actuation of an end effector.

One way to minimize or prevent an overall change in the length of an actuation element due to bending is to arrange the actuation element along a twisted path as it passes through a bending portion of a surgical instrument. For instance, an actuation element may be arranged along a twisted path having an angular extent of <NUM>° for each bending axis the actuation element passes through to substantially minimize or prevent a change in the overall length of the actuation element (i.e., conserve the length of the actuation element).

Turning to <FIG>, a schematic view of an exemplary embodiment of a wrist <NUM> of a surgical instrument is shown that includes a first actuation element <NUM> and a second actuation element <NUM>. Wrist <NUM> may include a joint (not shown in the schematic view of <FIG>) to cause bending of wrist <NUM> about a bend axis <NUM> (which extends into and out of the page of <FIG>). Wrist <NUM> is bent about the bend axis <NUM>, causing portions of actuation elements <NUM>, <NUM> above longitudinal axis <NUM> in <FIG> to experience a positive change in length and portions below axis <NUM> to experience a negative change in length. Because actuation elements <NUM>, <NUM> are arranged along a twisted path having an angular extent of <NUM>° about axis <NUM> through wrist <NUM>, actuation elements <NUM>, <NUM> do not substantially experience a change in length due to bending wrist <NUM> about axis <NUM>. For instance, although the portion of actuation element <NUM> in zone <NUM> experiences a positive change in length, the portion of actuation element <NUM> in zone <NUM> experiences a negative change in length that effectively cancels out the positive change in length from zone <NUM>. Similarly the negative change in length of actuation element <NUM> in zone <NUM> is canceled out by the positive change in length of actuation element <NUM> in zone <NUM>. Similar cancellations of changes in length between zones <NUM>, <NUM>, <NUM>, <NUM> occur for actuation element <NUM> but in the opposite manner because actuation element <NUM> is positioned opposite to actuation element <NUM> about axis <NUM>.

Turning to <FIG>, a schematic view of another exemplary embodiment of a wrist <NUM> is shown that includes a first actuation element <NUM> and a second actuation element <NUM>, with wrist <NUM> bent about a bend axis <NUM>. Similar to the exemplary embodiment of <FIG>, wrist <NUM> may include joint (not shown in the exemplary embodiment of <FIG>) to cause bending of wrist <NUM> about bend axis <NUM>. In the exemplary embodiment of <FIG>, at ends of zones <NUM>, <NUM> of wrist <NUM>, actuation elements <NUM>, <NUM> are positioned along neutral axis <NUM>, instead of being offset from neutral axis, as in the exemplary embodiment of <FIG>. However, the actuation elements <NUM>, <NUM> are arranged along a twisted path and offset from the longitudinal axis <NUM> in zones <NUM> and <NUM>. Because actuation elements <NUM>, <NUM> are arranged along a twisted path having an angular extent of <NUM>° as they pass through wrist <NUM>, the overall lengths of actuation elements <NUM>, <NUM> do not substantially change. For instance, although the portion of actuation element <NUM> in zone <NUM> experiences a positive change in length, the portion of actuation element <NUM> in zone <NUM> experiences a negative change in length that cancels the positive change in length. Actuation element <NUM> experiences a similar cancellation of changes in length but in the opposite manner. The portions of actuation elements <NUM>, <NUM> in zones <NUM>, <NUM> do not experience any significant change in length relative to each other along the longitudinal axis <NUM>.

As discussed above with regard to the exemplary embodiments of <FIG>, actuation elements offset from a central longitudinal axis (neutral axis) of a surgical instrument may be arranged along a twisted path having an angular extent of <NUM>° for a bend axis of the surgical instrument. However, a surgical instrument may include several bend axes. For instance, a wrist of a surgical instrument may include one or more multi-DOF (degree of freedom) joints and thus plural bend axes. For instance, if wrist <NUM> of the exemplary embodiment of <FIG> includes a plurality of bend axes <NUM> extending in substantially the same direction, actuation elements <NUM>, <NUM> may be arranged along a twisted path having an angular extent of <NUM>° across both bend axes instead of just one bend axis.

According to another exemplary embodiment, a wrist including a first plurality of bend axes extending in one direction, such as in the direction of bend axis <NUM> in <FIG>, and a second plurality of bend axes extending in another direction, such as substantially perpendicular to bend axis <NUM> in <FIG>, actuation elements may be arranged along a twisted path having an angular extent of <NUM>° across the first plurality of bend axes and along a twisted path having an angular extent of <NUM>° across the second plurality of bend axes. However, twisting actuation elements along a twisted path to result in minimal or no change of length for each bend axis (e.g., when the bend axes extend in different or alternating directions) may result in increased friction between a twisted actuation element and surfaces that support and/or guide the actuation element into a twisted shape. Friction between an actuation element and its supporting surfaces may be represented by the capstan equation, Tload = TholdeµΦ, in which Thold is tension applied to the actuation element, µ is the coefficient of friction between the actuation element and support surface, Φ is the total angle swept by the twist of the actuation element, and Tload is the force between the actuation element and supporting surface. Twisting an actuation element through a large angle of Φ thus results in a large Tload force between the actuation element and the support surface(s). Thus, twisting an actuation element <NUM> degrees for each joint, when the joints have bend axes extending in different or alternating directions, may pose difficulties in manufacturing, particularly for a relatively short length and small diameter of a wrist of a surgical instrument. In view of these considerations, the present disclosure contemplates surgical instruments including one or more joints that conserve the length of one or more actuation elements when bent (i.e., the overall length of the actuation elements does not significantly change when bent) while also minimizing the amount of twist to accomplish length conservation.

Various exemplary embodiments useful to provide length conservation of actuation elements are contemplated by the present disclosure and are discussed in further detail below with regard to jointed structures of a surgical instrument. Various jointed structures can use actuation element configurations that follow a twisted path. For example, the jointed structures may be for wrists, such as, for example, a wrist configured according to the exemplary embodiments of <CIT> under attorney docket number ISRG04480PROV/US, and International <CIT> (ISRG04480/PCT), filed on a date even herewith and claiming priority to <CIT>. In another example, the jointed structures may be used in joggle joints, such as, for example, the joggle joints described in <CIT>, and in U.

Another type of joint with which exemplary embodiments of the present disclosure can be utilized is shown in the exemplary embodiment of <FIG>. As noted above, <FIG> shows wrist <NUM> connected to an end effector <NUM>. End effector <NUM> may include, for example, a clevis <NUM> and jawed member <NUM>, according to an exemplary embodiment. According to an exemplary embodiment, wrist <NUM> includes a first link <NUM> connected to end effector <NUM> and a second link <NUM>, with a joint <NUM> connecting first link <NUM> to end effector <NUM> and a joint <NUM> connecting second link <NUM> to first link <NUM>. The links in various exemplary embodiments described herein can be configured as disks, as those having ordinary skill in the art are familiar with. However, other shapes can also be employed without departing from the scope of the disclosure and claims. In exemplary embodiments in which end effector <NUM> is directly jointed to first link <NUM> via joint <NUM>, at least a portion of end effector <NUM> is a part of wrist <NUM>.

According to another exemplary embodiment, a wrist may include three links instead of two links. For instance, instead of having link <NUM> directly connected to a clevis <NUM> to provide a joint <NUM> between link <NUM> and clevis <NUM>, as shown in the exemplary embodiment of <FIG>, a third link may be provided between link <NUM> and clevis <NUM>, with joint <NUM> formed between link <NUM> and the third link and the link attached to clevis.

First link <NUM> and clevis <NUM> may be articulated relative to one another about axis <NUM> (which extends into and out of the page of <FIG>) in direction <NUM>. Wrist <NUM> further includes a second link <NUM> connected to first link <NUM> so that second link <NUM> and first link <NUM> may be articulated relative to one another about axis <NUM> in direction <NUM>. Axes <NUM>, <NUM> are substantially orthogonal to one another to provide wrist <NUM> with two degrees of freedom, such as motion in arbitrarily selected pitch and yaw directions. Because wrist <NUM> has two degrees of freedom with motion in different directions, wrist <NUM> may be described as an "AB" wrist, which refers to the two different motions provided by the joints <NUM>, <NUM> of wrist <NUM>.

The exemplary embodiments described herein may be used in wrists other than "AB" type wrists. For example, wrists may include a plurality of joints of the same bend axis type, which can provide a larger range of motion of a wrist. Turning to <FIG>, an exemplary embodiment of a wrist <NUM> is shown that includes links <NUM>-<NUM>. Links <NUM> and <NUM> are connected so that they may articulate relative to one another about axis <NUM> in direction <NUM>. Links <NUM> and <NUM> are connected to one another in substantially the same way as links <NUM> and <NUM>, with links <NUM> and <NUM> articulating relative to one another about axis <NUM> in direction <NUM>. Thus, the joint <NUM> between links <NUM> and <NUM> and the joint <NUM> between links <NUM> and <NUM> are the same type and may be referred to as "A" joints. Links <NUM> and <NUM> are connected so that they may articulate relative to one another about axis <NUM> (which extends into and out of the page of <FIG>) in direction <NUM>. Axes <NUM>, <NUM> may be substantially orthogonal to one another to provide wrist <NUM> with two degrees of freedom, such as motion in arbitrary pitch and yaw (or A and B) directions. Further, links <NUM> and <NUM> are connected to one another in substantially the same way as links <NUM> and <NUM>, with links <NUM> and <NUM> articulating relative to one another about axis <NUM> (which extends into and out of the page of <FIG>) in direction <NUM>. The joint <NUM> between links <NUM> and <NUM> and the joint <NUM> between links <NUM> and <NUM> are the same type and may be referred to as "B" joints. Thus, wrist <NUM> may be referred to as an "ABBA" wrist, which refers to the order of the bend axis types of the joints along wrist <NUM>.

In another example, a wrist may have an "ABAB" configuration. Such a configuration, for instance, may include two "AB" joints, such as the links <NUM>, <NUM> of the exemplary embodiment of <FIG> in series so that two "AB" joints are directly connected to one another in an "ABAB" configuration.

Due to the small size of a wrist for a surgical instrument and the various complicated components of a wrist, which may have different movements in different directions, various issues arise in passing actuation elements through a wrist, including determining how to pass actuation elements through a wrist to minimize how much the actuation element extends in a twisted shape through the wrist while substantially conserving the length of the actuation element as the wrist is bent. The inventive embodiments concern a wrist of a surgical instrument in which one or more actuation elements extend along a twisted path having an angular extent of less than <NUM>° along the entire length of the wrist. These designs account for, among other things, for example, the angular extent traversed by an actuation element along a twisted path across an entire length of a wrist, the angular extent traversed by an actuation element along a twisted path across individual bending axes, the angular extent traversed by an actuation element and the resulting friction between the actuation element and support surface(s) (i.e., minimizing the angular extent minimizes the amount of friction to overcome, such as per the capstan equation, when applying a force to actuate the actuation element), and the initial angle of an actuation element relative to a bending axis.

Turning to <FIG>, cross-sectional schematic views are shown of two joints 1000A and 1000B of a wrist. The wrist can be structured similarly to the wrist <NUM> of the exemplary embodiment of <FIG>, according to an exemplary embodiment. For instance, the cross-sections of joints 1000A and 1000B in <FIG> may be schematic views along lines A-A and B-B of the exemplary embodiment of an AB wrist in <FIG>, but modified to show the amount of twist of actuation elements 316A, 316B as they extend across each joint 1000A and 1000B. Actuation elements 316A, 316B may be used, for example, to actuate an end effector (such as end effector <NUM> of the exemplary embodiment of <FIG>) or to actuate another component of an instrument, such as, for example, a wrist. According to an exemplary embodiment, actuation elements 316A, 316B may follow a twisted path so that actuation of actuation elements 316A, 316B does not result in an inverted motion, such as when actuation elements 316A, 316B are used to actuate a wrist.

The cross-sections in <FIG> respectively represent two different joints 1000A and 1000B of a wrist with the cross-section for joint 1000A representing a joint (such as joint <NUM> in the exemplary embodiment of <FIG>) having a bending axis <NUM> and cross-section for joint 1000B representing a joint (such as joint <NUM> in the exemplary embodiment of <FIG>) having a bending axis <NUM>.

The actuation elements of the various exemplary embodiments described herein may be substantially length conservative. Thus, although in some cases an actuation element may have zero change in length when joint(s) through which the actuation element extends are actuated, such as one or more joints of a wrist, in some cases the actuation element may experience a small amount of change in length. According to an exemplary embodiment, a substantially length conservative actuation element may experience a change in length of, for example, less than about <NUM> (<NUM> inches), including no change in length, such as when <NUM> (<NUM> pounds) or less of tension is applied to the actuation element.

The angular extent of twist of actuation elements 316A, 316B may be selected to make actuation elements 316A, 316B length conservative over the wrist. For instance, each of actuation elements 316A, 316B may have a twist of <NUM>° for each joint 1000A, 1000B of the wrist, as shown in <FIG>. In other words, actuation elements 316A, 316B may have an angular extent of <NUM>° with respect to centerline <NUM> for each joint 1000A,<NUM> B. For example, actuation element 316A may be arranged along a twisted path having an angular extent of about <NUM>° from an initial position <NUM> to a subsequent position <NUM> across joint 1000A. Further, actuation element 316A may be twisted <NUM>° from an initial position <NUM> (corresponding to subsequent position <NUM> in the cross-section for joint 1000A) to a subsequent position <NUM> across joint 1000B.

To facilitate viewing of the twist of an actuation element, <FIG> shows a schematic top view of a wrist310 including the joints depicted in <FIG>, with only actuation element 316A shown along the length of the joints 1000A, 1000B of wrist <NUM> to illustrate the shape of actuation element 316A along different joints of wrist310. In <FIG>, wrist310 has been schematically segmented into joint 1000A and joint 1000B to show the amount of twist of actuation element 316A along each of joints 1000A and 1000B. According to an exemplary embodiment, joint 1000A may have a length <NUM> and joint 1000B may have a length <NUM>, which are schematically shown in the exemplary embodiment of <FIG> for purposes of depicting the amount of twist for joints 1000A and 1000B. With reference to the exemplary embodiment of <FIG>, joint 1000A may correspond to, for example, joint <NUM>, with the twist for joint 1000A being substantially centered at joint <NUM> and extending for substantially equal amounts on either side of joint <NUM>.

Similarly, with reference to the exemplary embodiment of <FIG>, joint 1000B may correspond to, for example, joint <NUM>, with the twist for joint 1000B being substantially centered at joint <NUM> and extending for substantially equal amounts on either side of joint <NUM>. As shown in <FIG>, actuation element 316A may be twisted from an initial position <NUM> to a subsequent position <NUM> over joint 1000A and twisted from an initial position <NUM> to a subsequent position <NUM> over joint 1000B. According to an exemplary embodiment, the twist of an actuation element may be substantially continuous, as shown in <FIG>, as actuation element 316A is twisted over joints 1000A and 1000B. Using a substantially continuous twist may beneficially minimize the amount of friction between an actuation element and support structure because the twist may occur over a longer longitudinal length of a wrist.

The twist of actuation elements, however, is not limited to the substantially continuous twists shown in the exemplary embodiment of <FIG>. For instance, actuation elements may be twisted into sections having varying amounts of twist along the length of the actuation elements. In another instance, actuation elements may instead follow a discontinuous twisted path including twisted portions separated by one or more regions in which an actuation element extends straight and substantially parallel to the neutral axis of a wrist. In such discontinuous twist embodiments, the twist of actuation elements 316A, 316B may still be in the amounts shown in <FIG> (i.e., <NUM>°) but over a shorter span of the lengths <NUM>, <NUM> of joints 1000A and 1000B in <FIG> due to the inclusion of one or more straight, non-twisted portions of actuation elements 316A, 316B.

As best shown in <FIG>, actuation element 316A is twisted <NUM>° for each of joints 1000A and 1000B about a neutral axis <NUM> (i.e., has a twisted shape with an angular extent of <NUM>° with respect to centerline <NUM> for each of joints 1000A and 1000B). According to an exemplary embodiment, neutral axis <NUM> may be a longitudinal centerline of wrist <NUM>. In addition, axis <NUM> may be a longitudinal centerline of wrist <NUM> as well as a centerline for the twisted path that the actuation elements 316A, 316B follow, according to an exemplary embodiment. Actuation element 316A may be radially spaced a distance <NUM> from neutral axis <NUM>, as shown in the cross-section of joint 1000B in <FIG>. Actuation element 316B is also spaced radial distance <NUM> from neutral axis, as shown in the cross-section of joint 1000B in <FIG>. Radial distance <NUM> may vary according to the diameter of wrist <NUM>. Radial distance <NUM> may be, for example, greater than about <NUM> to about <NUM> when an actuation element does not extend along neutral axis <NUM> (e.g., is spaced a non-zero radial distance from neutral axis <NUM>). According to another exemplary embodiment, radial distance <NUM> may be, for example, greater than about <NUM> to about <NUM> According to an exemplary embodiment, radial distance <NUM> may be maximized so that actuation elements 316A, 316B are spaced at or near the periphery of joints 1000A and 1000B, such as to maximize an internal space within wrist <NUM>. According to another exemplary embodiment, radial distance <NUM> may be minimized so that actuation elements 316A, 316B are spaced near neutral axis <NUM>, such as when actuation elements 316A, 316B and/or guide lumens for actuation elements 316A, 316B are difficult to bend.

Similarly to actuation element 316A, actuation element 316B may also be twisted <NUM>° (i.e., have an angular extent of <NUM>° along a twisted path about centerline <NUM>) from an initial position <NUM> to a subsequent position <NUM> in the joint represented by cross-section 1000A, as shown in <FIG>. Further, actuation element 316B may be twisted <NUM>° from an initial position <NUM> (coincident with subsequent position <NUM> in cross-section 1000B) to a subsequent position <NUM> in the joint represented by cross-section 1000B, as shown in <FIG>. Thus, each of actuation elements 316A, 316B may have a total of <NUM>° of twist (i.e., have an angular extent of <NUM>° along a twisted path about centerline <NUM>) over the entire length of wrist <NUM> to make actuation elements 316A, 316B length conservative over wrist <NUM>. This results in an overall twist of each actuation element 316A, 316B being substantially smaller than a <NUM>° twist.

For instance, when considering the twist of actuation element 316A about centerline <NUM>, such as when neutral axis <NUM> is an origin in a polar coordinate system, actuation element 316A is twisted through an angle measure of <NUM>° across the entire length of wrist <NUM> from initial position <NUM> in joint 1000A to subsequent position <NUM> in joint 1000B. This is further illustrated in the exemplary embodiment of <FIG>, which depicts a twisted path <NUM>. As shown in the exemplary embodiment <FIG>, twisted path <NUM> extends in a twisted shape around a longitudinal axis <NUM> (i.e., centerline <NUM>) from a first end <NUM> to a second end <NUM>. To show the angular extent of twisted path <NUM>, twisted path <NUM> may be projected as an arc <NUM> having a radius of curvature <NUM> onto a plane <NUM>, with points on arc <NUM> corresponding to locations on twisted path <NUM>. For instance, point <NUM> on arc <NUM> may correspond to a first end <NUM> of twisted path <NUM> and point <NUM> on arc <NUM> may correspond to a point <NUM> approximately halfway along the length of twisted path <NUM>.

Although twisted path <NUM> is depicted in the exemplary embodiment of <FIG> as having a substantially constant radius of curvature <NUM>, twisted path <NUM> (and therefore arc <NUM>) may include sections having differing curvatures and/or may also include one or more straight sections. Therefore, when a twisted path is discussed in the exemplary embodiments herein, the twisted path may twist with a substantially continuous radius of curvature or may include sections with differing radii of curvature, including curved sections with differing radii of curvature and/or straight sections.

As shown in <FIG>, an angular extent <NUM> between point <NUM> and point <NUM> on arc <NUM>, relative to centerline <NUM> (which may also be projected onto plane <NUM>), is approximately <NUM>°. Thus, when the angular extent of a twisted path is discussed in the exemplary embodiments herein, the angular extent may be determined according to angular extent <NUM> relative to centerline <NUM>, as shown in <FIG>. Further, because twisted path <NUM> completes a full <NUM>° twist from first end <NUM> to second end <NUM>, point <NUM> on arc <NUM> corresponds to both first end <NUM> and second end <NUM>, with the angular extent <NUM> between first end <NUM> and second end <NUM> being <NUM>°. Thus, in the exemplary illustration of <FIG>, arc <NUM> forms a complete circle. However, in other embodiments in which a twisted path does not complete a <NUM>° twist, arc <NUM> will not complete a circle because the angular extent of the twisted path is less than <NUM>°.

Twisting actuation elements 316A, 316B in the manner shown in <FIG> can permit actuation elements 316A, 316B to be length conservative for wrist <NUM>. Further, according to an exemplary embodiment, the angular extent of twist of actuation elements 316A, 316B may be selected to make actuation elements 316A, 316B length conservative for each of joints 1000A and 1000B. For example, for joint 1000A, approximately half of each of the actuation elements 316A, 316B is on the left side of bend axis <NUM> and approximately half of each of the actuation elements 316A, 316B is on the right side of bend axis <NUM>, as shown in the schematic depiction of the exemplary embodiment of <FIG>. As a result, any positive or negative change in length for the portion of actuation elements 316A, 316B on the left side of bend axis <NUM> is offset by any negative or positive change in length for the portion of actuation elements 316A, 316B on the right side of bend axis <NUM>. Thus, there is substantially no net change in length for actuation elements 316A, 316B, making each of actuation elements 316A, 316B length conservative across joint 1000A. Similarly, for joint 1000B, approximately half of each actuation elements 316A, 316B is on the top side and on the bottom side of bend axis <NUM>, as shown in the schematic depiction of the exemplary embodiment of <FIG>, so that any change in length for the top side of actuation elements 316A, 316B relative to bend axis <NUM> is substantially offset by any change in length for the bottom side of actuation elements 316A, 316B relative to bend axis <NUM>. Thus, there is substantially no net change in length for actuation elements 316A, 316B, making actuation elements 316A, 316B length conservative across joint 1000B.

An amount of twist of an actuation member across a joint may also be schematically represented by the average angular position of the actuation member over a length of a joint. For instance, an average angular position <NUM> of actuation element 316A with regard to neutral axis over the length <NUM> of joint 1000A is schematically shown in <FIG>. In other words, as actuation elements 316A twists through <NUM>° across the length <NUM> of joint 1000A, such as when neutral axis <NUM> is treated as an origin in a polar coordinate system, an average angular position <NUM> of actuation element 316A may be determined. When average angular position <NUM> of actuation element 316A across the length <NUM> of joint 1000A lines up with bend axis <NUM> for joint 1000A, as shown in <FIG>, this indicates that actuation element 316A is length conservative for joint 1000A. Actuation element 316A has an average angular position <NUM> across the length <NUM> of joint 1000B that also lines up with bend axis <NUM>, as shown in <FIG>. Further, because actuation element 316B is positioned opposite to actuation element 316A and substantially mirrors the twist of actuation element 316A, the average angular positions of actuation element 316B across joints 1000A and 1000B may be considered to be the same as average angular positions <NUM>, <NUM> of actuation element 316A.

As noted above, various exemplary embodiments account for an initial angle of an actuation element to a bending axis. An initial angle may be considered an initial angle of an actuation element to a bend axis as the actuation element enters a joint. As shown in the exemplary embodiment of <FIG>, actuation element 316A may have an initial angle <NUM> at its initial position <NUM> to bend axis <NUM> in joint 1000A. According to an exemplary embodiment, initial angle <NUM> may be approximately <NUM>°, particularly when actuation element is twisted <NUM>° along the length <NUM> of joint 1000A so that a substantially equal amount of actuation element may be located on either side of bend axis <NUM>, as shown in the cross-sectional view of <FIG>. Because actuation element 316B may be positioned opposite to actuation element 316A across neutral axis <NUM>, an initial position <NUM> of actuation element 316B in joint 1000A may be at approximately the same angle <NUM> with respect to bend axis <NUM>, such as, for example, approximately <NUM>°. In joint 1000B the initial positions <NUM>, <NUM> of actuation elements 316A, 316B may be at an angle to bend axis <NUM> that is approximately the same as angle <NUM> in joint 1000A.

Other initial angles also may be utilized, however, such as when smaller or larger amounts of angular extent (twist) are used over a given joint. For example, an initial position <NUM> of actuation element 316A may be at an angle <NUM> of approximately <NUM>° with respect to bend axis <NUM>. In such an example, an amount of twist of actuation element 316A over joint 1000A may be approximately <NUM>° so that a substantially equal amount of actuation element 316A may be positioned on either side of bend axis <NUM> and actuation element 316A is length conservative across joint 1000A. Other values for initial angle <NUM> are contemplated by the exemplary embodiments herein, such as, for example, about <NUM>° to about <NUM>°, according to an exemplary embodiment.

Various exemplary embodiments in accordance with the present disclosure contemplate other initial positions actuation element twist configurations than those shown and discussed with reference to the exemplary embodiment of <FIG>. With reference to <FIG>, a schematic cross-sectional view is shown of a joint of an exemplary embodiment of a wrist. The joint 1200A depicted in the exemplary embodiment of <FIG> may be an A type joint similar to the exemplary embodiment of <FIG>, except that the initial positions of actuation elements 330A, 330B in joint 1200A are aligned with bend axis 332A. Actuation elements 330A, 330B may be used, for example, to actuate an end effector (such as end effector <NUM> of the exemplary embodiment of <FIG>) or to actuate another component of an instrument, such as, for example, a wrist. According to an exemplary embodiment, actuation elements 330A, 330B may follow a twisted path so that actuation of actuation elements 330A, 330B does not result in an inverted motion, such as when actuation elements 330A, 330B are used to actuate a wrist.

As shown in <FIG> and in <FIG>, the latter of which is a top schematic view of a wrist <NUM> including the joints depicted in <FIG> but showing only the twist of actuation element 330A, actuation element 330A does not have a twist along the length <NUM> of joint 1200A relative to the longitudinal neutral axis <NUM>. As discussed above with regard to <FIG>, axis <NUM> may be a centerline for wrist <NUM> and in addition may be a centerline for the twisted path of actuation elements 330A, 330B. Thus, the average angular position <NUM> of actuation elements 330A, 330B over a length <NUM> of joint 1200A (shown schematically in <FIG>) is lined up with bend axis 332A (i.e., bend axis 332A passes through actuation elements 330A, 330B). As a result, actuation elements 330A, 330B are already length conservative in joint 1200A and need not be twisted in that joint. However, in joint 1200B, the respective initial positions 331A, 335A of actuation elements 330A, 330B are offset from bend axis 332B. For example, initial positions 331A, 335A of actuation elements 330A, 330B may be offset by approximately <NUM>° from bend axis 332B in joint 1200B.

To achieve length conservation of actuation elements 330A, 330B across joint 1200B, actuation elements 330A, 330B may be twisted an angular extent of <NUM>° to respective subsequent positions 331B, 335B (i.e., follow a twisted path over an angular extent of <NUM>° about centerline <NUM>). As a result, an approximately equal amount of each of actuation elements 330A, 330B is on either side of bend axis 332B in joint 1200B (e.g., the top and bottom side in the cross-section of joint 1200B in FIG. This is also demonstrated by the average angular position <NUM> of actuation elements 330A, 330B over a length <NUM> of joint 1200B (shown schematically in <FIG>), which aligns with bend axis 332B (i.e., bend axis 332B passes through average angular position <NUM> of actuation elements 330A, 330B). Thus, actuation elements 330A, 330B may follow a twisted path having an angular extent of <NUM>° over the length of wrist <NUM>, similar to the exemplary embodiment of <FIG>, but with no twisting occurring over the length of one joint (e.g., joint 1200A) and all of the twisting occurring over the length of another joint (e.g., joint 1200B). Further, actuation elements 330A, 330B may be twisted in this manner to make each of actuation elements 330A, 330B length conservative across each of joints 1200A and 1200B.

Wrists can be configured to include any number of joints with varying bend axes directions for each joint. Some nonlimiting examples contemplated as within the scope of the present disclosure include a wrist having one or more multiples of wrists <NUM> and/or <NUM> of the exemplary embodiments of <FIG>, with the length of actuation elements being substantially conserved over the total length of the wrist. For instance, a wrist could include two consecutive wrist devices each configured according to either of the exemplary embodiments of <FIG>. Such a wrist can include, for example, in sequence, a first A joint, a first B joint, a second A joint, and a second B joint (i.e., the wrist would be an ABAB type of wrist). To achieve length conservation of actuation elements extending across the length of the wrist, the actuation elements may extend along a twisted path having an angular extent of <NUM>° over the length of the wrist, which is twice the angular extent for each of wrist <NUM>, <NUM> of the exemplary embodiments of <FIG>. Conversely, a wrist including two consecutive wrist devices (e.g., an ABAB type of wrist) may be simplified to a wrist including a single wrist, such as the wrists <NUM> and/or <NUM> of the exemplary embodiments of <FIG> (e.g., an AB type of wrist). Similarly, an AABB type of wrist could be simplified to an AB wrist.

Various exemplary embodiments in accordance with the present disclosure contemplate various bending axis patterns of a wrist and twist configurations for actuation elements. Although wrist configurations may include only joints with two bending axes, as shown in <FIG> and <FIG> other wrist configurations may be used, such as the ABBA wrist of the exemplary embodiment of <FIG>.

Turning to <FIG>, cross-sectional views are shown of joints of a wrist that includes four joints 1400A1, 1400B1, 1400B2, 1400A2, according to an exemplary embodiment. For instance, the wrist may be constructed according to the exemplary embodiment of the ABBA wrist of <FIG> and the respective cross-sectional views of joints A1, B1, B2, and A2 in <FIG> may be views along lines A1-A1, B1-B1, B2-B2, A2-A2 in <FIG>. Thus, the cross-sections of joints 1400A1, 1400B1, 1400B2, 1400A2 in <FIG> respectively represent four different joints of the wrist <NUM> schematically shown in the exemplary embodiment of <FIG>, with joint 1400A1 having a bending axis <NUM> and a length <NUM> (schematically shown in <FIG>), joint 1400B1 having a bending axis <NUM> and a length <NUM> (schematically shown in <FIG>), joint 1400B2 having a bending axis <NUM> and a length <NUM> (schematically shown in <FIG>), and joint 1400A2 having a bending axis <NUM> and a length <NUM> (schematically shown in <FIG>). Further, wrist <NUM> has a longitudinal neutral axis <NUM>, as shown in <FIG> and <FIG>. Axis <NUM> may be a centerline for wrist <NUM> and may further be a centerline for the twisted path of actuation elements <NUM>, <NUM>. Actuation elements <NUM>, <NUM> may be used, for example, to actuate an end effector, or to actuate another component of an instrument, such as, for example, a wrist. According to an exemplary embodiment, actuation elements <NUM>, <NUM> may follow a twisted path so that actuation of actuation elements <NUM>, <NUM> does not result in an inverted motion (e.g., joints <NUM> and <NUM> in <FIG> do not bend in different directions about axes <NUM> and <NUM>, and joints <NUM> and <NUM> do not bend in different directions about axes <NUM> and <NUM>), such as when actuation elements <NUM>, <NUM> are used to actuate a wrist. According to an exemplary embodiment, the twist of actuation elements <NUM>, <NUM> for each of joints 1400A1,1400B1, 1400B2, 1400A2 may be centered about the respective bending axes <NUM>, <NUM>, <NUM>, <NUM>, with the twisted path extending in a substantially equal amount on either side of the respective bending axes <NUM>, <NUM>, <NUM>, <NUM>.

The angular extent of twist of actuation elements <NUM>, <NUM> extending across wrist <NUM> is such that actuation elements <NUM>, <NUM> are length conservative over the length of wrist <NUM>. In joint 1400A1, both of actuation elements <NUM>, <NUM> are aligned with bend axis <NUM> (i.e., bend axis <NUM> passes through actuation elements <NUM>, <NUM>) and thus have an average angular position <NUM> across the length <NUM> of joint 1400A1 that is aligned with bend axis <NUM>. Thus, both of actuation elements <NUM>, <NUM> do not substantially change in length in joint 1400A1 and are not twisted in that joint. In joint 1400B1, actuation element <NUM> has an initial position <NUM> as it enters from joint 1400A1 that has an approximately <NUM>° angle <NUM> to bend axis <NUM>. Actuation element <NUM> also has an initial position <NUM> as it enters from joint A1 that is at an approximately <NUM>° angle to bend axis <NUM>.

In the exemplary embodiment of <FIG>, actuation elements <NUM>, <NUM> may be twisted <NUM>° (i.e., follow a twisted path having an angular extent of <NUM>° about the centerline <NUM>) in joint 1400B1 to respective subsequent positions <NUM>, <NUM>, providing actuation elements <NUM>, <NUM> with an average angular position <NUM> across the length <NUM> of joint 1400B1. As shown in the exemplary embodiment of <FIG>, average angular position <NUM> is not aligned with bend axis <NUM>, resulting in a positive or negative change in length for actuation elements <NUM>, <NUM> in joint 1400B1. In joint 1400B2, actuation element <NUM> has an initial position <NUM> after entering from joint 1400B1 at an angle <NUM> of <NUM>° relative to bend axis <NUM> and actuation element <NUM> has an initial position <NUM> at <NUM>° to bend axis <NUM>, as shown in <FIG>. Actuation elements <NUM>, <NUM> are twisted <NUM>° (i.e., follow a twisted path having an angular extent of <NUM>° about centerline <NUM>) in joint 1400B2 to provide an average angular position <NUM> across the length <NUM> of joint 1400B2, resulting in a positive or negative change in lengths for each of actuation elements <NUM>, <NUM> in joint 1400B2.

However, the twists of actuation elements <NUM>, <NUM> in joints 1400B1, 1400B2 are on opposite sides of bend axes <NUM>, <NUM>, as indicated by average angular positions <NUM>, <NUM> across the respective lengths <NUM>, <NUM> of joints 1400B1, 1400B2, and the changes in length of actuation elements <NUM>, <NUM> substantially cancel one another out. Further, actuation elements <NUM>, <NUM> are aligned with bend axis <NUM> (i.e., bend axis <NUM> passes through actuation elements <NUM>, <NUM>) in joint 1400A2, as indicated by average angular position <NUM> of actuation elements <NUM>, <NUM> across the length <NUM> of joint 1400A2. As a result, actuation elements <NUM>, <NUM> are twisted <NUM>° (i.e., the twisted path has an angular extent of <NUM>° about centerline <NUM>) through the entire length of wrist <NUM> (i.e., <NUM>° through each of joints 1400B1 and 1400B2). Further, because the twists of actuation elements <NUM>, <NUM> relative to bend axes <NUM>, <NUM> of joints 1400B1, 1400B2 are on opposite sides of bend axes <NUM>, <NUM>, actuation elements <NUM>, <NUM> do not experience a substantial change of length in joints 1400A1, 1400A2, and any positive or negative change of length of actuation elements <NUM>, <NUM> in joint B1 is offset by a corresponding negative or positive change in length of actuation elements <NUM>, <NUM> in joint 1400B2, and vice versa. Thus, each actuation element <NUM>, <NUM> is length conservative over the entire length of wrist <NUM>.

The present disclosure contemplates other configurations for wrists having more than two joints. Turning to <FIG>, cross-sectional views are shown of joints 1600A1, 1600B1, 1600B2, 1600A2 of a wrist. Wrist <NUM> may be constructed, for example, according to the exemplary embodiment shown in <FIG> and the cross-sectional views of joints 1600A1, 1600B1, 1600B2, and 1600A2 in <FIG> may be views along lines A1-A1, B1-B1, B2-B2, and A2-A2 for the exemplary embodiment of an ABBA wrist in <FIG>.

According to an exemplary embodiment, joint 1600A1 having a bending axis <NUM> and a length <NUM> (shown schematically in the exemplary embodiment of <FIG>, which shows the entire wrist <NUM> and includes the joints depicted in <FIG>), joint 1600B1 having a bending axis <NUM> and a length <NUM> (shown schematically in <FIG>), joint 1600B2 having a bending axis <NUM> and a length <NUM> (shown schematically in <FIG>), and joint 1600A2 having a bending axis <NUM> and a length <NUM> (shown schematically in <FIG>). Further, wrist <NUM> may include a longitudinal neutral axis <NUM> that extends through joints 1600A1, 1600B1, 1600B2, 1600A2, as shown in <FIG> and <FIG>. Axis <NUM> may be a centerline for wrist <NUM> and may also be a centerline for the twisted path of actuation elements <NUM>, <NUM>. Actuation elements <NUM>, <NUM> may be used, for example, to actuate an end effector, or to actuate another component of an instrument, such as, for example, a wrist. According to an exemplary embodiment, actuation elements <NUM>, <NUM> may follow a twisted path so that actuation of actuation elements <NUM>, <NUM> does not result in an inverted motion (e.g., joints <NUM> and <NUM> in <FIG> do not bend in different directions about axes <NUM> and <NUM>, and joints <NUM> and <NUM> do not bend in different directions about axes <NUM> and <NUM>), such as when actuation elements <NUM>, <NUM> are used to actuate a wrist.

In the exemplary embodiment of <FIG> and <FIG>, actuation elements <NUM>, <NUM> may be initially offset and not aligned from bend axis <NUM> in joint 1600A1. For instance, actuation elements <NUM>, <NUM> may initially be at an angle <NUM> of approximately <NUM>° to bend axis <NUM>. To address this, actuation elements <NUM>, <NUM> may be twisted <NUM>° (i.e., follow a twisted path having an angular extent of <NUM>° about centerline <NUM>) from respective initial positions <NUM>, <NUM> to subsequent positions <NUM>, <NUM> along the length <NUM> of joint 1600A1 so that actuation elements <NUM>, <NUM> are length conservative in joint 1600A1. Thus, the average angular position <NUM> of actuation elements <NUM>, <NUM> across the length <NUM> of joint 1600A1 aligns with bend axis <NUM> (bend axis <NUM> passes through average angular position <NUM> of actuation elements <NUM>, <NUM>).

Similarly, actuation elements <NUM>, <NUM> may be twisted <NUM>° (i.e., follow a twisted path having an angular extent of <NUM>° about centerline <NUM>) in joint 1600B1 from respective initial positions <NUM>, <NUM> to subsequent positions <NUM>, <NUM>; twisted <NUM>° (i.e., follow a twisted path having an angular extent of <NUM>° about centerline <NUM>) in joint 1600B2 from respective initial positions <NUM>, <NUM> to subsequent positions <NUM>, <NUM>; and twisted <NUM>° (i.e., follow a twisted path having an angular extent of <NUM>° about centerline <NUM>) in joint 1600A2 from respective initial positions <NUM>, <NUM> to subsequent positions <NUM>, <NUM>. Similar to jointA1, the average angular position <NUM> of actuation elements <NUM>, <NUM> across the length <NUM> of joint 1600A2 aligns with bend axis <NUM> so that actuation elements <NUM>, <NUM> are substantially length conservative across joint 1600A2. Actuation elements <NUM>, <NUM> are not length conservative over the lengths <NUM>, <NUM> of each of joints 1600B1, 1600B2. However, when taken in total over the combined lengths <NUM> and <NUM> of joints 1600B1 and 1600B2, actuation elements <NUM>, <NUM> are substantially lengths conservative over the combination of joints 1600B1 and 1600B2. This is indicated by the average angular position <NUM> of actuation elements <NUM>, <NUM> across the length <NUM> of joint 1600B1 and the average angular position <NUM> of actuation elements <NUM>, <NUM> across the length <NUM> of joint 1600B2 which are on opposite sides of their respective bending axes <NUM> and <NUM>. Thus, actuation elements <NUM>, <NUM> may be twisted a total amount of <NUM>° (i.e., have a twisted path having an angular extent of <NUM>° about centerline <NUM>) over the entire length of wrist <NUM> (i.e., twisted <NUM>° across each of the lengths of joints 1600A1, 1600B1, 1600B2, 1600A2).

To extend an actuation element along a twisted path, as described in the exemplary embodiments above, various exemplary embodiments contemplate one or more structures that guide one or more actuation elements along a twisted path. One or more structures may provide support to the actuation element along its length to minimize or reduce buckling of the actuation element as the actuation element extends along the twisted path according to the exemplary embodiments described herein, such as the exemplary embodiments of <FIG>.

Turning to <FIG>, a distal portion of a surgical instrument is shown, including an actuation element support <NUM> located at a distal end of an instrument shaft, such as the shaft <NUM> of the exemplary embodiment of <FIG>. According to an exemplary embodiment, a first portion <NUM> of actuation element support <NUM> may include twisted passages <NUM>, <NUM> that provide a twisted path for actuation elements <NUM>, <NUM> that extend through passages <NUM>, <NUM> of first portion <NUM>. Actuation elements <NUM>, <NUM> may extend out of a proximal end <NUM> of support <NUM> and into a second portion <NUM> of actuation element support <NUM>, which includes substantially straight passages <NUM>, <NUM> through which actuation elements <NUM>, <NUM> may extend, as shown in the exemplary embodiment of <FIG>. Although only two passages <NUM>, <NUM> are depicted in the exemplary embodiment of <FIG> for ease of illustration, second portion <NUM> of actuation element support <NUM> may include the same number of passages as first portion <NUM>. According to an exemplary embodiment, the passages of second portion <NUM> may be joined to the passages of first portion <NUM> so that any actuation elements extending through the passages of second portion <NUM> extend through corresponding passages in first portion <NUM>.

According to an exemplary embodiment, support <NUM> may further include a central passage <NUM> through which an actuation element <NUM> may extend. Central passage <NUM> may extend along a longitudinal centerline <NUM> of instrument so that any member extending through central passage <NUM>, such as actuation element <NUM> or a flux conduit, does not experience a substantial change in length when support <NUM> is bent. Centerline <NUM> may also be a centerline of support <NUM>, according to an exemplary embodiment. Actuation element <NUM> may be used, for example, to actuate an end effector, such as, for example, a cutting blade. The actuation elements of the various exemplary embodiments described herein that are radially offset from a neutral axis or centerline are not limited to actuating an end effector or wrist, but may be used to actuate other instrument components. For example, the actuation elements of the various exemplary embodiments described herein that are radially offset from a neutral axis or centerline may actuate a second wrist distal to actuation element support <NUM>, or other instrument component. In another example, actuation element <NUM> may be used to actuate an end effector, while actuation elements <NUM>, <NUM> are used to actuate the wrist that end effector is connected to. According to another example, a flux conduit may extend through central passage <NUM> instead of actuation element <NUM>.

One or more actuation elements may extend from actuation element support <NUM> and connect to a device used to actuate an instrument component. As shown in the exemplary embodiment of <FIG>, actuation element support <NUM> may include a central lumen <NUM>, such as for a flux conduit or actuation element <NUM> (which may further extend through a lumen <NUM> of connector <NUM>), lumens <NUM> for actuation elements <NUM>, <NUM>, and two additional lumens <NUM> that may be used for other actuation elements or flux conduits. According to an exemplary embodiment, actuation elements <NUM>, <NUM> and connector <NUM> may form a push/pull actuation element that actuates an end effector, such as when actuation elements <NUM>, <NUM> and connector are pushed or pulled along direction <NUM>. Turning to <FIG>, a side view of an end effector <NUM> is shown in a closed configuration, with projections <NUM> of connector <NUM> extending through a slot <NUM> of end effector <NUM>. When actuation elements <NUM>, <NUM>, connector <NUM>, and projection <NUM> are pushed in direction <NUM>, projection <NUM> moves through slot <NUM> and forces end effector <NUM> into an open configuration, as shown in <FIG>.

Although actuation elements <NUM>, <NUM> may be used as push/pull actuation elements, actuation elements <NUM>, <NUM> may instead be used as a pull/pull actuation element. For instance, actuation elements <NUM>, <NUM> may be attached to a proximal end <NUM> of end effector <NUM> without using connector <NUM> so that end effector <NUM> may be opened by pulling on one of actuation elements <NUM>, <NUM> and closed by pulling the other of actuation elements <NUM>, <NUM>.

According to an exemplary embodiment, an actuation element support may be positioned in a surgical instrument so that the location of the support corresponds to the location of a wrist because the wrist can bend, which could cause actuation elements extending through the wrist to change in length. Because central passage <NUM> is located along longitudinal centerline <NUM> of instrument, actuation elements <NUM>, <NUM> and their respective passages <NUM>, <NUM> are radially offset from centerline <NUM>. Thus, when wrist <NUM> is actuated to bend the instrument, such as to position end effector <NUM> in a desired location, actuation elements <NUM>, <NUM> might experience a change in length. However, support <NUM> imparts a twisted path to actuation elements <NUM>, <NUM>, such as according to the exemplary embodiments of <FIG>, so that actuation elements <NUM>, <NUM> do not experience a substantial change in length over the length of wrist <NUM>.

Passages <NUM>, <NUM> are twisted <NUM>° in the exemplary embodiment of <FIG> but other configurations of twist may be used, as described in the exemplary embodiments of <FIG>. Actuation element support <NUM> may include various numbers of passages to provide a twisted path for one or more actuation elements. For instance, actuation element support <NUM> may include one passage, two passages, three passage, or four or more passages. For instance, actuation element support <NUM> may include a third passage <NUM> and a fourth passage <NUM>, which may be used for additional actuation elements or for flux conduits <NUM>, <NUM>, such as electrical conductors to provide electrical energy to an end effector (not shown).

As shown in the exemplary embodiment of <FIG>, actuation element support <NUM> may have a solid, single-piece construction with passages <NUM>-<NUM> formed through the length of support <NUM>. According to an exemplary embodiment, actuation element support <NUM> may be manufactured, for example, by extruding a polymer material into a substantially cylindrical shape with twisted passages <NUM>-<NUM> formed through the length of the polymer material. However, other manufacturing methods may be utilized to provide a support <NUM> having one or more twisted passages radially offset from and twisting about a centerline <NUM> of support <NUM>. Thus, support <NUM> may guide one or more actuation elements along a twisted path and provide support to the actuation elements to minimize or eliminate buckling of the actuation elements. For instance, when an actuation element is used as a push/pull actuation element and the actuation element is pushed, support <NUM> may reduce or eliminate buckling of the actuation element.

In various exemplary embodiments, support <NUM> may be flexible to promote bending of support <NUM> when a wrist that support <NUM> extends through is actuated. Support <NUM> may be made from, for example, a polymer material to provide a relatively low coefficient of friction. According to an exemplary embodiment, support <NUM> may be made of, for example, polyether block amide (PEBAX), fluorinated ethylene propylene (FEP), and other polymer materials having a relatively low coefficient of friction familiar to one skilled in the art. In addition, actuation elements extending through support <NUM> may be coated with a material to minimize friction between the actuation elements and support <NUM>. For example, actuation elements may be coated with polytetrafluoroethylene (PTFE) or other lubricious material familiar to one skilled in the art.

As shown in the exemplary embodiment of <FIG>, an actuation element support <NUM> may include five lumens <NUM>, <NUM>, <NUM>. However, a surgical instrument, including an actuation element support, is not limited to only five members and a greater or lesser number of lumens may be used in an instrument. For instance, an actuation element support <NUM> may include seven lumens <NUM> as shown in the exemplary embodiment of <FIG>. In addition, lumens of an actuation element support need not be arranged as a single ring of lumens around a central lumen, as in the exemplary embodiment of <FIG>. Instead, lumens <NUM> of a support <NUM> may be arranged in a plurality of concentric rings around a central lumen, as shown in the exemplary embodiment of <FIG>.

As discussed above with regard to the exemplary embodiment of <FIG>, an actuation element support may have a single-piece construction. For instance, the support may be a single piece that has been extruded. Such an extrusion may have a solid, substantially continuous outer surface without grooves. However, other configurations and constructions may be used for an actuation element support. For instance, an actuation element support may include one or more areas of material weakness to enhance the flexibility of the support. Turning to <FIG>, an exemplary embodiment of an actuation element support <NUM> is shown, with actuation elements <NUM>, <NUM> extending through support <NUM>. To enhance the flexibility of support <NUM>, such as when support <NUM> is bent by a wrist, support <NUM> may include one or more areas of material weakness, such as grooves <NUM>, as shown in the exemplary embodiment of <FIG>. According to an exemplary embodiment, support <NUM> may be formed as an extrusion with lumens formed through support <NUM>, similar to the exemplary embodiment of <FIG>, and then have grooves <NUM> cut into the extrusion to provide vertebrae <NUM> separated by grooves <NUM>. As shown in <FIG>, which is a cross-sectional view along line <NUM>-<NUM> in <FIG>, support <NUM> may include five lumens <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, similarly to the exemplary embodiment of <FIG>. However, support <NUM> may include other numbers of lumens and may include the lumen configurations of the exemplary embodiments of <FIG>. According to an exemplary embodiment, support <NUM> may include other areas of weakness besides grooves. For instance, support <NUM> may include apertures <NUM>, which may be formed in vertebrae <NUM>, to provide additional areas of weakness and enhanced flexibility to support <NUM>.

According to an exemplary embodiment, actuation elements may be supported and shaped into a twisted path by components other than the single piece constructions of <FIG>, <FIG>. Turning to <FIG>, an exploded view is shown of an actuation support <NUM> that is formed by a plurality of separate links <NUM>-<NUM>, according to an exemplary embodiment. Links <NUM>-<NUM> may include one or more passages <NUM>, <NUM> for actuation elements (not shown). As shown in the exemplary embodiment of <FIG>, links <NUM>-<NUM> may be rotated about a longitudinal axis <NUM> (i.e., centerline) of support <NUM> in direction <NUM> to impart a twist to actuation elements passing through passages <NUM>, <NUM>. Thus, passages <NUM>, <NUM> of links <NUM>-<NUM> may have a different angular position with respect to centerline <NUM> from one link to another. Links <NUM>-<NUM> may impart other amounts of twist, such as the amounts of twist discussed in the exemplary embodiments of <FIG>. In addition, links <NUM>-<NUM> may include other numbers of lumens and may include the lumen configurations of the exemplary embodiments of <FIG>.

As shown in the exemplary embodiment of <FIG>, lumens <NUM>-<NUM> of an actuation element support <NUM> may twist in one direction from one end of support <NUM> to another. However, actuation element supports are not limited to such a twisted configuration and may instead include lumens that twist in more than one direction. Turning to <FIG>, an exemplary embodiment of an actuation element support <NUM> is shown that includes lumens <NUM>, <NUM> that twist in a first direction <NUM> along support <NUM> in direction <NUM> and then reverse to twist along direction <NUM>. Further, the amount of twist may be constant along the length of a support or may vary by increasing or decreasing along the length of a support.

As discussed above, an actuation element support may function both to guide an actuation element along a twisted path and to support the actuation element to minimize or prevent buckling of the actuation element. Other structures may be provided to enhance the support of an actuation element and its buckling strength, which may be used with an actuation element support. Turning to <FIG>, an exemplary embodiment of an actuation element <NUM> is shown that includes a rigid section <NUM> at a distal end of an unsupported section <NUM> of actuation element <NUM>. As shown in <FIG>, which is an enlarged view of portion <NUM> in <FIG>, actuation element <NUM> may include a wire or cable <NUM> that extends into rigid section <NUM>. Wire or cable <NUM> may be, for example, one of actuation elements <NUM>, <NUM> of the exemplary embodiment of <FIG>. Rigid section <NUM> may include a rigid cylinder <NUM> fitted over wire or cable <NUM>. Rigid cylinder <NUM> may made of, for example, steel, such as stainless steel. Rigid cylinder <NUM> may be connected to wire or cable <NUM> via, for example, crimping cylinder <NUM> to wire or cable <NUM>.

According to an exemplary embodiment, unsupported section <NUM> of wire or cable <NUM> may include a coating <NUM>. Coating <NUM> may be used, for example, to provide wire or cable <NUM> with a smooth surface having a lower coefficient of friction than wire or cable <NUM>. Coating <NUM> may be made of polymer, such as a thermoplastic. According to an exemplary embodiment, coating <NUM> may be made of, for example, PTFE, ethylene tetrafluoroethylene (ETFE), silicone, or other coating materials familiar to one skilled in the art. According to an exemplary embodiment, coating <NUM> may have a thickness that is substantially the same as the thickness of cylinder <NUM>, as shown in <FIG>.

By providing actuation element <NUM> with a rigid section <NUM>, the buckling strength of actuation element <NUM> may be enhanced. For instance, when actuation element <NUM> is inserted through an actuation element support <NUM> (e.g., actuation element support <NUM> of the exemplary embodiment of <FIG>), actuation element <NUM> may be pushed along direction <NUM>, causing a distal end of actuation element <NUM> to extend beyond a distal end <NUM> of actuation element support <NUM>, as shown in the exemplary embodiment of <FIG>. Because actuation element <NUM> includes a rigid section <NUM>, the portion of actuation element <NUM> that extends beyond the distal end <NUM> of actuation element support <NUM> may have enhanced buckling strength. For instance, a surgical instrument may be configured so that when actuation element <NUM> is pushed along direction <NUM>, only the rigid section <NUM> of actuation element <NUM> extends beyond distal end <NUM> of actuation element support <NUM>, as shown in <FIG>, with the unsupported section <NUM> of actuation element <NUM> remaining within actuation element support <NUM>.

According to an exemplary embodiment, a proximal end of actuation element <NUM> may also include a rigid section <NUM>, as shown in <FIG>, although other exemplary embodiments may lack a rigid section at a proximal end of an actuation element. The rigid section <NUM> at proximal end may be configured according to the rigid section <NUM> of the exemplary embodiment of <FIG>. According to an exemplary embodiment, rigid section <NUM> may extend past a proximal end of an actuation element support, such as when actuation element is pulled, similar to the exemplary embodiment of <FIG>.

Another structure that may be used to support an actuation element is a flexible shaft. Turning to <FIG>, an exemplary embodiment of a flexible shaft <NUM> is shown, which includes a compression member <NUM> and a tension member <NUM>. Flexible shaft <NUM> may be used to support an actuation element, with flexible shaft <NUM> extending through at least a portion of an actuation element support, similar to the exemplary embodiment of <FIG>. Compression member <NUM> may have a central lumen <NUM> for an actuation element to pass through. Compression member <NUM> may be, for example, a spring including windings that compress against one another when a compressive force is applied along a longitudinal axis <NUM> of flexible shaft <NUM>. Tension member <NUM> may be a wire or cable attached to compression member <NUM>, such as on the exterior of compression member <NUM>, to resist tensile forces applied along axis <NUM> or bending forces applied to flexible shaft <NUM>. In other words, flexible shaft <NUM> may be a combination of a compression member <NUM> that resists compression, which could otherwise compress tension member <NUM> if compression member <NUM> were not present, and a tension member <NUM> that resists tension and bending, which could otherwise pull apart compression member <NUM>.

According to an exemplary embodiment, an actuation element support may include a plurality of flexible shaft layers. For example, an actuation element support may include multiple flexible shafts layered over one another, such as by providing multiple layers of the flexible shaft <NUM> of the exemplary embodiment of <FIG> over one another. The various layers of the flexible shafts may be coaxial to one another. For example, as shown in the exemplary embodiment of <FIG>, an actuation element support <NUM> may include a first flexible tube <NUM> and a second flexible tube <NUM> coaxial to one another, with one or more actuation elements <NUM> extending through support <NUM>. Although only two coaxial tubes <NUM>, <NUM> are depicted in the exemplary embodiment of FIG. <NUM>, support <NUM> may include other numbers of coaxial tubes, such as, for example, three, four, or more flexible coaxial tubes. Flexible tubes <NUM>, <NUM> may be flexible due to removal of material from the tubes <NUM>, <NUM>, such as via cutting grooves or slits in tubes <NUM>, <NUM> to provide areas of weakness that permit tubes <NUM>, <NUM> to flex, according to an exemplary embodiment. According to an exemplary embodiment, tubes <NUM>, <NUM> may be solid wound springs, which are useful for compression loads, with would filaments, which are useful for tensile loads.

According to another exemplary embodiment, a flexible shaft for supporting an actuation member may include multiple layers of wound filaments connected together. For example, instead of including the compression member <NUM> of the exemplary embodiment of <FIG>, a flexible shaft may include a plurality of tension members <NUM> connected together, such as by weaving tension members <NUM> together. According to an exemplary embodiment, an actuation element support may be a flexible shaft formed by a tube with portions removed, such as via, for example, cutting the tube in one or more locations, to enhance the flexibility of the tube. The tube may be made of, for example, stainless steel, a thermoplastic, or other material one skilled in the art is familiar with.

The exemplary embodiments and methods described herein have been described as being utilized with surgical instruments for teleoperated surgical systems. However, the exemplary embodiments and methods described herein may be used with other surgical devices, such as laparoscopic instruments and other hand held instruments. Further, the exemplary embodiments and methods may be employed in other application that use remotely actuatable wrist or multiple joint structures, such as to remotely position an object attached to the wrist or joint structures.

By providing surgical instruments with an actuation element configured to substantially conserve its length when the surgical instrument is bent, the actuation element may be permitted to actuate a component of the instrument without substantial interference from a change in its length and the surgical instrument may have a simplified design that is relatively easy to manufacture.

Claim 1:
A surgical instrument (<NUM>, <NUM>, <NUM>, <NUM>), comprising:
a shaft (<NUM>, <NUM>, <NUM>) comprising a first end;
a wrist (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) coupled to the first end of the shaft and comprising a first joint (<NUM>, <NUM>) and a second joint (<NUM>, <NUM>), the first joint having a single first bend axis (<NUM>, <NUM>) and the second joint having a single second bend axis (<NUM>, <NUM>), the first and second bend axes (<NUM>, <NUM>, <NUM>, <NUM>) being orthogonal to one another;
an end effector (<NUM>, <NUM>, <NUM>, <NUM>) coupled to the wrist; and
an actuation element (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, 316A, 316B, 330A, 330B, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) that extends along the shaft and the wrist;
wherein the actuation element follows a twisted path along at least a portion of the wrist; and
wherein the twisted path has an angular extent of less than <NUM> degrees along an entire length of the wrist.