Patent Description:
Aspects of the present disclosure relate to articulatable wrist joints, and to surgical instruments and related systems and methods utilizing such wrist joints.

Remotely controlled surgical instruments (also referred to as teleoperated surgical instruments) are often used in minimally invasive medical procedures. A surgical instrument may include joints to position the surgical instrument in a desired location. Because the range of motion of an individual joint can be limited, multiple joints having the same or similar motion may be necessary to provide a desired range of motion that exceeds the range of motion for an individual joint. However, use of multiple joints requires additional components to control and support the additional joints, which can increase the complexity in operation, overall size, and difficulty of manufacturing the instrument.

<CIT> discloses surgical tools having a two degree-of-freedom wrist, wrist articulation by linked tension members, mechanisms for transmitting torque through an angle, and minimally invasive surgical tools incorporating these features. An elongate intermediate wrist member is pivotally coupled with a distal end of an instrument shaft so as to rotate about a first axis transverse to the shaft, and an end effector body is pivotally coupled with the intermediate member so as to rotate about a second axis that is transverse to the first axis. Linked tension members interact with attachment features to articulate the wrist. A torque-transmitting mechanism includes a coupling member, coupling pins, a drive shaft, and a driven shaft. The drive shaft is coupled with the driven shaft so as to control the relative orientations of the drive shaft, the coupling member, and the driven shaft.

<CIT> discloses a medical instrument comprising a shaft that includes at least two adjacent shaft sections which are movable relative to one another. The at least two movable shaft sections are engaged with each other so as to roll off one another in a frictionally locking manner or so as mesh with each other by means of teeth.

<CIT> discloses a tool for minimally invasive surgery comprising, an elongated shaft having a predetermined length, an adjustment handle manually controllable by a user, a pitch direction handling part and a yaw direction handling part positioned around one end of the elongated shaft for transferring motions in pitch and yaw directions following the actuation of the adjustment handle, a pitch direction actuating part and a yaw direction actuating part positioned around the other end of the elongated shaft for operating corresponding to the operations from the pitch direction handling part and the yaw direction handling part, respectively, an end effector controllable by the pitch direction actuating part and the yaw direction actuating part, and a plurality of cables for transferring the from the pitch direction handling part and the yaw direction handling part to the pitch direction actuating part and the yaw direction actuating part, respectively.

The present invention is set out in the appended independent claim.

No methods of treatment or surgery are claimed.

Optional features are set out in the appended dependent claims. Other features and/or advantages may become apparent from the description that follows.

In accordance with at least one example, a wrist joint comprises a first disc, a second disc adjacent the first disc, and a drive tendon that extends through the first disc and the second disc. The first disc and the second disc may comprise respective opposing joint features that intermesh with one another. The first disc and the second disc may further comprise opposing load bearing surfaces separate from the joint features. The drive tendon may be configured to exert a force on at least one of the first and second discs to cause relative rotation between the first and second discs. The first and second discs may have a maximum rotational range of motion greater than about +/- <NUM> degrees relative to each other.

In accordance with at least one example, a surgical instrument comprises a shaft, an end effector coupled to a first end of the shaft, a transmission mechanism, and a wrist joint. The transmission mechanism may be disposed at a second end of the shaft opposite the first end. The transmission mechanism may transmit drive forces through actuation elements to actuate the end effector. The wrist joint may couple the end effector to the shaft. The wrist joint may comprise a pair of adjacent discs coupled together and have a maximum range of motion greater than +/- <NUM> degrees.

In accordance with at least one example, a surgical instrument comprises a shaft, an end effector coupled to a first end of the shaft, a transmission mechanism, and an articulatable wrist. The transmission mechanism may be disposed at a second end of the shaft opposite the first end. The transmission mechanism may transmit drive forces through actuation elements to actuate the end effector. The articulatable wrist may couple the end effector to the shaft. The articulatable wrist may comprise a first disc and a second disc. The first disc may have a plurality of teeth and a first load bearing surface separate from the plurality of teeth. The second disc may have a plurality of pins configured to intermesh with the teeth and a second load bearing surface separate from the plurality of pins. Further, the first load bearing surface and the second load bearing surface may engage each other to bear compressive forces of the wrist.

In accordance with at least one example, a method of articulating a wrist joint comprises applying a force to a drive tendon coupled to at least one of a first disc and a second disc of the wrist joint, causing the first disc and the second disc to rotate relative to one another. During rotation of the first and second discs, at least one of a plurality of teeth of one of the first and second discs remain intermeshed with at least one of a plurality of pins of the other of the first and second discs when the discs are rotated relative to one another more than about +/- <NUM> degrees, and load bearing surfaces of the first and second discs remain in contact with one another. Further, the load bearing surfaces of the first and second discs are radially spaced from the teeth and pins.

In accordance with at least one example, a method of making a wrist joint comprises configuring a first disc with a plurality of teeth and a first load bearing surface separate from the plurality of teeth. The method may further comprise configuring a second disc with a plurality of pins and a second load bearing surface separate from the plurality of pins. A drive tendon may be extended through the first disc and the second disc. The method may further comprise coupling the first and second disc to one another so that the first and second joint features intermesh and the first and second load bearing surfaces contact one another. Further, the first and second discs may have a maximum rotational range of motion greater than about +/- <NUM> degrees relative to each other.

Additional 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 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; rather the claims should be entitled to their full breadth of scope.

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 disclosure 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. Various mechanical, compositional, structural, electrical, and operational changes may be made without departing from the scope of this description.

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, 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 invention. For example, spatially relative terms-such as "beneath", "below", "lower", "above", "upper", "proximal", "distal", "clockwise", "counterclockwise", 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.

In accordance with various exemplary embodiments, the present disclosure contemplates surgical instruments that include a joint that can achieve a relatively large range of motion. For example, a joint may have a maximum range of motion that permits discs of the joint to rotate relative to each other more than +/-<NUM> degrees. In one example, a joint may include a plurality of teeth and pins that intermesh with one another so the joint may have repeatable movements. A disc may include one or more recesses to accommodate a tooth of another disc. A recess, for example, may have a trochoid shape. In another example, a joint may have a plurality of teeth to engage with pins and a separate load bearing surface. The load bearing surface may be located radially inward, such as a location closer to a central aperture of a disc than the teeth or pins of the disc, or the load bearing surface may be located radially outward, such as a location further from a central aperture of a disc than the teeth or pins of the disc. The load bearing surface may have a shape of a partial cylinder, a cycloidal shape, the shape of pins, or other shapes. In another example, the positions of pins of a disc may be altered relative to a circular arc, which may represent a contact surface between discs, such as a load bearing surface, and a theoretical arc through points of contact between pins and gears. For a disc having a load bearing surface with a partial cylindrical shape, the circular arc may have the same shape as the surface of the load bearing surface. By altering the position of one or more pins relative to the arc, the ease of manufacturing the disc and the smoothness of the disc's motion may be affected. For instance, all pins of the disc may be located on the circular arc, all pins may be offset from the circular arc, or at least one pin may be offset and at least one pin may be located on the circular arc. There may also be multiple pins, with the pins offset a different distance from the circular arc from one another.

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 a robotic 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 mechanism (not shown in <FIG>) at the distal end of main shaft <NUM>, and an end effector <NUM> extending from wrist mechanism or directly from the shaft <NUM>. <FIG> illustrates a distal end <NUM> of a surgical instrument that includes 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, pull/pull tendons or push/pull rods, and electrical conductors that are connected to a wrist mechanism <NUM> and/or end effector <NUM> of an instrument may extend through shaft <NUM> of instrument, as shown in <FIG>. Further, the actuation elements may extend through main shaft <NUM> and connect to transmission mechanism <NUM>. Transmission mechanism <NUM> typically provides a mechanical coupling of the drive tendons 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>.

The actuation interface may generally include drive motors that provide mechanical power for operation of surgical instruments <NUM>. System <NUM> can thus control movement and tension in the tendons as needed to move or position wrist mechanism 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 mechanism 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 mechanism 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 mechanism and/or end effector <NUM> at a worksite inside the patient.

The diameter or diameters of main shaft <NUM>, wrist mechanism, 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 mechanism and main shaft <NUM> may range from about <NUM> to about <NUM>. For example, the diameter may be 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 robotic 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 input 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> and/or arms <NUM> to which the surgical instruments <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.

Surgical instrument joints, such as wrist joints, may move according to one or more degrees of freedom to provide motion to a surgical instrument or a camera instrument that includes the joint. For instance, a joint may include a plurality of members that may move relative to one another in one or more degrees of freedom (e.g., arbitrarily defined as pitch and/or yaw). A joint of a surgical instrument or a camera instrument may include various numbers of members. For example, a joint of a surgical instrument or a camera instrument may be a one-piece joint (e.g., a single piece designed to bend in one or more directions, such as due to structurally flexible portions provided in the piece), a two-piece joint (such as two discs, which may also be referred to as vertebrae, directly connected to one another), a three-piece joint (such as two discs and a third piece connecting the two discs), or joints including greater numbers of pieces.

Although the description below discusses joint configurations in the context of their application in surgical instruments, a person of ordinary skill in the art would understand that the joint configurations may be applied to camera instruments. Further, although the description below discusses joint configurations that are two-piece joints, the concepts of the description may also apply to joints including larger numbers of pieces, such as a three-piece joint or a joint including a greater number of pieces.

Joint members of the exemplary embodiments described herein may include features having cycloidal surface profiles, for example as are described in U. Joint members having cycloidal shapes are less prone to jamming, such as when joint members are compressed together, in comparison to joint members having more common involute shapes. In addition, the epicycloid <NUM> and the hypocycloid <NUM> shown in <FIG> of U. No. <CIT> include concave and convex contact areas, which provide relatively large contact areas for distributing forces between cycloids <NUM>, <NUM>. As a result, the stress between cycloidal surfaces may be reduced for a given load and cycloidal surfaces may experience reduced deformation under load.

As discussed in U. No. <CIT>, geared movement in a wrist mechanism may result when two members in the wrist mechanism have relative angular orientations that change according to a fixed relationship or gear ratio. As shown in FIGS. 1A and 1B of U. No. <CIT>, members <NUM>, <NUM> of a wrist joint <NUM> may respectively have bearing surfaces <NUM>, <NUM> that are circular, permitting surfaces <NUM>, <NUM> to roll on each other during geared movement when members <NUM>, <NUM> rotate relative to one another. Member <NUM> may include a tooth <NUM> that can engage the walls of an aperture (recess) <NUM> of member <NUM> to prevent slipping, such as due to translation movement between members <NUM>, <NUM>. The combination of tooth <NUM> and walls of aperture <NUM> may be referred to as a pin gear. Therefore, a joint may include features to minimize or eliminate translation of joint members relative to one another. A surgical instrument, such as a wrist of a surgical instrument, may include a plurality of joints that bend in this manner. For instance, a surgical instrument may include multiple joints oriented relative to one another to provide multiple degrees of freedom for motion of the surgical instrument, such as via bending in pitch and yaw directions.

According to an exemplary embodiment, features of joint members used to minimize or eliminate translation between joint members may also enhance the repeated movement of joint members. For instance, after members <NUM>, <NUM> have been rotated relative to one another, as shown in FIGS. 1A and 1B of U. No. <CIT>, such as to bend a wrist of a surgical instrument, a user may wish to straighten the wrist, such as by reversing the rotation of members <NUM>, <NUM>. If either rotation resulted in a substantial displacement of members <NUM>, <NUM> relative to one another in a lateral direction and/or a direction along a longitudinal axis of a surgical instrument, subsequent movements of members <NUM>, <NUM> relative to one another may be less smooth. Further, substantial displacement between members <NUM>, <NUM> could affect the control of movement between the members <NUM>, <NUM> and a user may observe the displacement. By respectively providing members <NUM>, <NUM> with tooth <NUM> and aperture <NUM>, repeated movement of members <NUM>, <NUM> may be enabled with minimal translation. Thus, joint members may be configured to have substantially repeatable movements. This ability of joint members to repeat movements by substantially returning joint members to their original positions may be referred to as the timing of a joint. For example, tooth <NUM> of member <NUM> and aperture <NUM> of member <NUM> may act as structures to provide timing to substantially return members <NUM>, <NUM> to their original positions, such as the neutral state shown in the exemplary embodiment of FIG.

In pin gears of joint discs, such as the pin gear provided by tooth <NUM> of member <NUM> and aperture <NUM> of member <NUM> of U. No. <CIT>, a maximum amount of rotation permitted between adjacent discs including a pin gear may be limited to, for example, about +/- <NUM> degrees relative to a longitudinal axis of a joint. A maximum range of motion of, for example, up to about +/- <NUM> degrees may be achieved for the overall motion of a wrist of a surgical instrument by using two sets of disc joints that include a pin gear, with each set of disc joints providing a maximum rotation of +/- <NUM> degrees relative to a longitudinal axis of a joint. However, the use of two sets of disc joints imposes an additional manufacture cost and requires other additional parts, such as control cables and motors in the backend components, for a surgical instrument. In view of these considerations, it may be desirable to provide a wrist joint having a relatively large maximum range of motion, for example, greater than about +/- <NUM> degrees. Thus, in such a wrist joint, the joint may provide a controlled, articulated motion through and greater than about +/- <NUM> degrees. In addition, it may be desirable to provide a wrist with a smooth motion and achieves "timing.

Turning to <FIG>, an exemplary embodiment of a joint <NUM> for a wrist of a surgical instrument is shown. Joint <NUM> includes a first disc <NUM> and a second disc <NUM>, as shown in <FIG>. Thus, according to an exemplary embodiment, joint <NUM> may be a two-piece joint in which first disc <NUM> and second disc <NUM> are directly in contact with one another. For instance, discs <NUM>, <NUM> may be in direct contact without additional joint components interposed between discs <NUM>, <NUM>. The term "disc" is used in a general sense as the term is often used in describing a vertebra-like structure. Those having ordinary skill in the art will appreciate that the disc components of the joints can have various shapes and configurations not limited to circular cross-sections or annular shapes.

In contrast with joint members that include only a single tooth and corresponding aperture, such as members <NUM>, <NUM> of U. No. <CIT>, joint <NUM> may include discs <NUM>, <NUM> with respective joint features <NUM>, <NUM> that intermesh with one another. For instance, joint feature <NUM> of first disc <NUM> may include a first tooth <NUM> and a second tooth <NUM>, as shown in the exemplary embodiment of <FIG>, although other numbers of teeth may be utilized, such as, for example, three, four, or more teeth. Joint feature <NUM> of second disc <NUM> may include a first pin <NUM>, a second pin <NUM>, and a third pin <NUM> configured to engage with teeth <NUM>, <NUM>, as shown in <FIG>, although other numbers of pins may be utilized, such as, for example, four, five, or more pins. Pins <NUM>, <NUM>, <NUM> may each have a constant radius of curvature, according to an exemplary embodiment. The radius of curvature of a pin may differ from an adjacent portion of a disc. As a result, pins may differ in diameter from one another.

The radius of curvature of a pin is demonstrated in the exemplary embodiment of <FIG>, which shows a disc <NUM> including pins <NUM>, <NUM>, <NUM> having respective radii of curvature <NUM>, <NUM>, <NUM> with respect to their pin centers <NUM>, <NUM>, <NUM>. As shown in the exemplary embodiment of <FIG>, disc portions <NUM>, <NUM> adjacent to pins <NUM>, <NUM> have different radii of curvature, and therefore a different shape, than pins <NUM>, <NUM>. Similarly, stem <NUM> adjacent to pin <NUM> has a different radius of curvature, and therefore a different shape, than pin <NUM>. Further, although each pin <NUM>, <NUM>, <NUM> have the same radius of curvature, <NUM>, <NUM>, <NUM>, the radii <NUM>, <NUM>, <NUM> may differ from one another. For instance, each radii <NUM>, <NUM>, <NUM> may be different or at least one of radii <NUM>, <NUM>, <NUM> may differ from the others. In one example, radii <NUM> and <NUM> may be the same but radius <NUM> may differ.

According to an exemplary embodiment, teeth and pins may have cycloidal shapes, which are described in U. Turning to <FIG>, an exemplary embodiment of a joint <NUM> is shown that includes a disc <NUM> having a tooth <NUM> having a cycloidal shape and a disc <NUM> having pins <NUM>, <NUM> with cycloidal shapes. However, discs of a joint are not limited to a single tooth and two pins but instead may include two, three, or more teeth with cycloidal shapes and three, four, or more pins with cycloidal shapes. For instance, the exemplary embodiment of <FIG> depicts a joint <NUM> that includes a disc <NUM> having two teeth <NUM>, <NUM> with cycloidal shapes and a disc <NUM> including pins <NUM>, <NUM>, <NUM> with cycloidal shapes.

According to an exemplary embodiment, disc <NUM> may include the plurality of teeth at each end of disc <NUM> with regard to a proximal-distal direction <NUM>, as shown in <FIG>. Similarly, disc <NUM> may include the plurality of pins at each end of disc <NUM> with regard to the proximal-distal direction <NUM>. In various exemplary embodiments, when a disc includes joint features, which may be a plurality of teeth or pins at each of its ends or a plurality of teeth at one end and a plurality of pins at the other end, the teeth or pins at the opposite ends may be offset from one another by approximately <NUM> degrees in a circumferential direction, as shown in the exemplary embodiment of <FIG>.

Because joint <NUM> includes at least one disc with a plurality of teeth, joint <NUM> provides an enhanced range of motion between first disc <NUM> and second disc <NUM>. For instance, joint <NUM> may provide a maximum range of motion (up to a roll angle limit) of greater than +/- <NUM> degrees between first disc <NUM> and second disc <NUM>, such as, for example, when discs <NUM>, <NUM> are rotated relative to one another in direction <NUM>, such as for an arbitrary pitch or yaw motion, as shown in <FIG>. According to another example, joint <NUM> may provide a maximum range of motion of more than about +/- <NUM> degrees to about +/- <NUM> degrees between first disc <NUM> and second disc <NUM>. According to another example, joint <NUM> may provide a maximum range of motion of more than +/- <NUM> degrees to about +/- <NUM> degrees between first disc <NUM> and second disc <NUM>. According to another example, joint <NUM> may provide a maximum range of motion of more than +/- <NUM> degrees to about +/- <NUM> degrees between first disc <NUM> and second disc <NUM>. According to another example, joint <NUM> may provide a maximum range of motion of about +/- <NUM> degrees to about +/- <NUM> degrees between first disc <NUM> and second disc <NUM>. Joint <NUM> may provide even greater ranges of motion between discs <NUM>, <NUM>, such as a maximum range of motion (roll angle limit) of more than +/-<NUM> degrees to about +/- <NUM> degrees between first disc <NUM> and second disc <NUM>, or a maximum range of motion of about +/- <NUM> degrees to about +/- <NUM> degrees between first disc <NUM> and second disc <NUM>, although even higher ranges of motion (roll angle limits) between discs <NUM>, <NUM> may be accomplished.

Due to the enhanced range of motion provided by joint <NUM>, a wrist including joint <NUM> may provide a desired amount of motion, such as +/- <NUM> degrees in a pitch or yaw direction, in a more efficient manner with fewer parts. In previous wrist structures in which each joint is limited to a maximum roll angle of about <NUM> degrees, several such joints in series are needed to relatively large roll angle for the entire wrist mechanism. But, in accordance with aspects of the invention, fewer joints (and thus discs) may be required to achieve a relatively large range of motion in structures where each joint has a more limited range of motion than the overall range of motion for the structures. And as illustrated, a single joint can provide up to a <NUM>-degree roll angle limit, so that two joints with a <NUM>-degree roll angle limit are needed to achieve the same roll angle. In addition, the single-joint implementation has a shorter end effector throw distance from the centerline of the instrument shaft to the end effector tip, which allows better end effector access in small surgical sites. As a result, a manufacturing cost and complexity for a wrist that includes one or more joints <NUM> may be reduced while still achieving desired control over articulation. In addition, the plurality of teeth and corresponding plurality of pins included in discs <NUM>, <NUM> of joint <NUM> can provide enhanced timing to assist with accurately positioning discs <NUM>, <NUM>, including, for example, returning discs to a neutral position (e.g., zero angle roll alignment), and to enhance smoothness of the motion between discs <NUM>, <NUM>, such as when discs <NUM>, <NUM> are rotated in direction <NUM> relative to one another. In addition, the single-joint implementation has a shorter end effector throw distance from the centerline of the instrument shaft to the end effector tip, which allows better end effector access in small surgical sites. According to an exemplary embodiment, a wrist may include a plurality of joints <NUM> to achieve higher ranges of motion (up to roll limit angles), such as, for example, wrists having a range of motion of up to +/- <NUM> in a pitch or yaw direction. As shown in the exemplary embodiment of <FIG>, a wrist <NUM> may include a first joint <NUM> including a first disc <NUM> and a second disc <NUM> and a second joint <NUM> including a third disc <NUM> and a fourth disc <NUM> to achieve higher ranges of motion.

Joint features also may include other configurations to assist with how teeth and pins of the joint engage with one another. According to an exemplary embodiment, a recess <NUM> may be provided between teeth <NUM>, <NUM> of disc <NUM>, with recess <NUM> shaped to receive a central pin <NUM> of disc <NUM>, as shown in <FIG> and <FIG>. Further, joint features <NUM> of disc <NUM> may include recesses to receive the teeth <NUM>, <NUM>. For example, a recess <NUM> may be located between pins <NUM>, <NUM> to receive tooth <NUM> and a recess <NUM> may be located between pins <NUM>, <NUM> to receive tooth <NUM>, as shown in <FIG> and <FIG>. Providing recess <NUM> to receive pin <NUM> and recesses <NUM>, <NUM> to receive teeth <NUM>, <NUM> may permit closer coupling of teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM>, such as to permit teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> to extend further between each other. As a result, motion between discs <NUM>, <NUM> may be made even smoother and the timing of joint <NUM> may be enhanced. For instance, the ability of discs <NUM>, <NUM> to substantially return to the straight configuration shown in the exemplary embodiment of <FIG> after being rotated relative to one another, as shown in the exemplary embodiment of <FIG>, may be enhanced, which in turn enhances the ability of a wrist including joint <NUM> to repeat the rotation shown in <FIG> in substantially the same manner, for example, over multiple cycles.

According to an exemplary embodiment, pin recesses <NUM>, <NUM> also may be provided in locations lateral to or outside teeth <NUM>, <NUM>, as shown in <FIG> and <FIG>. Pin recesses <NUM>, <NUM> may be configured to receive pins <NUM>, <NUM> when discs <NUM>, <NUM> are rotated relative to one another, as illustrated in <FIG> (with recess <NUM> receiving pin <NUM>). As a result, pin recesses <NUM>, <NUM> may also assist with enhancing engagement between teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> (in other words to maintain tooth <NUM> in the recess between the pins <NUM>, <NUM> as depicted in <FIG>), even when discs <NUM>, <NUM> are rotated relative to one another at relatively high ranges of motion, such as up to about +/- <NUM> degrees or more, for example.

According to an exemplary embodiment, joint members that include a plurality of teeth may have at least one of the teeth become disengaged with corresponding pins during articulation of a joint. Intermesh and engage, as used herein when discussing joint features, such as teeth and pins, does not necessarily mean that joint features are in contact. As will be discussed below, joint features, such as teeth and pins, may be spaced apart from one another and not in contact during normal conditions, or joint features may be in contact with one another under normal conditions, such as to provide surfaces that bear a compressive load. For example, when intermeshed or engaged teeth and pins are not normally in contact during normal conditions, teeth and pins may subsequently come into contact with one another, such as when a lateral force and/or a torque causes discs to shift relative to one another in a lateral direction. Teeth and pins may also contact one another when discs shift relative to one another along a longitudinal direction, particularly when discs are already rotated relative to one another. When this occurs, a gap between at least one tooth and one or more pins closes, causing the intermeshed tooth and the pin(s) to contact one another, which substantially prevents further lateral movement between the discs and potential dislocation of the joint. As a result, the relative positions of the discs may be maintained, which enhances the timing of a joint including the discs and the minimization or elimination of the degree of freedom for movement of discs in a lateral direction, even when intermeshed or engaged joint features do not normally contact one another. In another example, intermeshed or engaged teeth and pins may be normally in contact with one another, such as when teeth and pins themselves serve as load bearing surfaces. For instance, in the exemplary embodiments of <FIG>, teeth <NUM>, <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may themselves serve as load bearing surfaces without additional load bearing projections.

<FIG> shows an exemplary embodiment of teeth and pins engaged in a neutral state of the joint <NUM>, with tooth <NUM> intermeshed with pins <NUM> and <NUM> and tooth <NUM> intermeshed with pins <NUM> and <NUM>. Further, pin <NUM> may be received in pin recess <NUM> and teeth <NUM>, <NUM> may be at least partially received in and located at outer edges of tooth recesses <NUM>, <NUM>, respectively. When discs <NUM>, <NUM> are rotated in direction <NUM>, as shown in the exemplary embodiment of <FIG>, the rotation can result in tooth <NUM> disengaging from corresponding pins <NUM>, <NUM> and being removed from the tooth recess <NUM>. However, in the position of <FIG>, when at least one tooth becomes disengaged due to relative rotation of discs, another tooth may remain engaged with corresponding pins so that the teeth and pins may continue to affect the positioning and timing of discs <NUM>, <NUM>. For instance, when discs <NUM>, <NUM> are rotated relative to one another in direction <NUM>, tooth <NUM> may remain engaged with pins <NUM> and <NUM>. Further, a majority of tooth <NUM> is received in tooth recess <NUM>, as shown in <FIG>.

As discussed above, a joint <NUM> including discs <NUM>, <NUM> may be provided in a wrist of a surgical instrument, such as wrist <NUM> in the exemplary embodiment of <FIG>. When used in a wrist of a surgical instrument, discs <NUM>, <NUM> may be pulled together by drive tendon (not shown), which may be used to control the motion of joint <NUM>, as discussed above for the exemplary embodiment of <FIG>, and to press discs <NUM>, <NUM> against one another to hold the components of the wrist together, as those having ordinary skill in the art are familiar with. According to an exemplary embodiment, disc <NUM> may include one or more tendon passages <NUM> to accommodate a corresponding number of tendons passing through disc <NUM>, as shown in <FIG>. Similarly, disc <NUM> may include one or more tendon passages <NUM>. According to an exemplary embodiment, a disc may include more than one passage for each tendon, such as when separate portions of the disc lie in an intended path of a tendon. For instance, disc <NUM> may include tendon passage <NUM> and another tendon passage <NUM> for the same tendon in another part of disc <NUM>. According to an exemplary embodiment, passages <NUM>, <NUM> are not aligned with one another along a direction extending substantially parallel to a longitudinal axis of joint <NUM>. Tendon passages <NUM>, <NUM>, <NUM> of the exemplary embodiment of <FIG> may have a larger diameter than the diameter of a tendon to permit the tendon to move back and forth within the passages when discs <NUM>, <NUM> are rotated relative to one another, according to an exemplary embodiment. According to an exemplary embodiment, a disc may include two tendon passages (such as when push/pull actuation members are utilized), three tendon passages, four tendon passages, or a higher number of tendon passages.

A consequence of a configuration in which tendons hold discs of a joint together is that a compressive load is applied between the discs. To address these compressive loads, exemplary joint members may include one or more joint features comprising load bearing surfaces to accommodate the compressive load. <FIG> illustrates another exemplary embodiment of a joint having similar elements as the exemplary embodiment of <FIG> and <FIG> but with additional joint features. For instance, disc <NUM> may include one or more bearing projections <NUM> having a load bearing surface <NUM> configured to receive a load, such as a compressive load, and disc <NUM> may include one or more bearing projections <NUM> having a load bearing surface <NUM> configured to receive the compressive load, such as by engaging with surface <NUM> of projection <NUM>, as shown in <FIG>. According to an exemplary embodiment, surfaces <NUM>, <NUM> may be configured to remain in contact with one another throughout motion of discs <NUM>, <NUM> relative to one another as long as a compressive load is applied between discs <NUM>, <NUM>.

As shown in the exemplary embodiment of <FIG>, surfaces <NUM>, <NUM> of bearing projections <NUM>, <NUM> may have the shape of a partial cylinder. However, the surfaces of the bearing projections of the exemplary embodiments described herein are not limited to partial cylinders and may instead have other shapes. According to an exemplary embodiment, bearing projections may have surfaces with cycloidal shapes, as described in <CIT>. For instance, a first bearing projection <NUM> may have a surface <NUM> with a cycloidal shape and a second bearing projection <NUM> may have a surface <NUM> with a cycloidal shape, as described in <CIT>. According to another exemplary embodiment, bearing projections may be provided by struts, as described in the exemplary embodiments of <CIT>. A strut may be provided as a separate piece connecting two adjacent discs, as described in <CIT>, thus providing a three-piece joint. For instance, as shown in the exemplary embodiment of <FIG>, a joint <NUM> may include a first disc <NUM> and a second disc <NUM> (each shown schematically in <FIG>) and a strut <NUM> configured to connect and bear the load between discs <NUM> and <NUM>. As shown in the exemplary embodiment of <FIG>, strut <NUM> may include projections <NUM> and a ring <NUM> connecting projections <NUM>. Each of discs <NUM> and <NUM> may include features to engage projections <NUM> to connect discs <NUM> and <NUM> via strut <NUM>, such as, for example, grooves <NUM> in disc <NUM>.

According to an exemplary embodiment, disc <NUM> may include a bearing projection <NUM> at each end of disc <NUM> with regard to the proximal-distal direction <NUM> shown in <FIG>. Similarly, disc <NUM> may include a bearing projection <NUM> at each end of disc <NUM>. When a disc includes a bearing projection at each of its ends, the projections at the opposite ends may be offset from one another by approximately <NUM> degrees in a circumferential direction, as shown in the exemplary embodiment of <FIG>. However, bearing projections are not limited to the configuration shown in <FIG> and instead may have positions in which bearing projections are substantially aligned along a longitudinal axis of discs instead of being offset from one another, such as to increase the range of motion of a wrist including the discs.

According to an exemplary embodiment, the bearing projections <NUM> and <NUM> may be separate from joint features <NUM>, <NUM> that include the teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM>, respectively. For instance, bearing projection <NUM> may be a physically separate, distinct member from pins <NUM>, <NUM>, <NUM>, as shown in <FIG>. Surface <NUM> of projection <NUM> may be a separate, distinct surface from surfaces provided by pins <NUM>, <NUM>, <NUM>. In addition, bearing projection <NUM> and bearing surface <NUM> may be a physically separate, distinct member from teeth <NUM>, <NUM>, as shown in <FIG>, and surface <NUM> of projection <NUM> may be a separate, distinct surface from surfaces provided by teeth <NUM>, <NUM>. According to an exemplary embodiment, projections <NUM>, <NUM> may be located in a different radial location than pins <NUM>, <NUM>, <NUM> and teeth <NUM>, <NUM> with respect to a central aperture <NUM> of disc <NUM> through which various control tendons, rod, and other instrument components may pass. According to an exemplary embodiment, bearing projection <NUM> may be located radially inward so that bearing projection <NUM> is located closer to central aperture <NUM> of disc <NUM> than joint feature <NUM>, which may include pins <NUM>, <NUM>, <NUM>, as shown in <FIG>. Similarly, bearing projection <NUM> may be located radially inward so that bearing projection <NUM> is located closer to central aperture (not shown) of disc <NUM> than joint feature <NUM>, which may include teeth <NUM>, <NUM>.

Although teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> and bearing projections <NUM>, <NUM> may be a part of discs <NUM>, <NUM> (i.e., have a one-piece construction with discs <NUM>, <NUM>), teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> and bearing projections <NUM>, <NUM> are not limited to such a configuration. For example, teeth <NUM>, <NUM> and/or pins <NUM>, <NUM>, <NUM> and/or bearing projections <NUM>, <NUM> may instead be provided as separate pieces connected to discs <NUM>, <NUM>.

As noted above, teeth and pins of discs may be spaced apart from one another during normal conditions, even when teeth <NUM>, <NUM> are engaged with pins <NUM>, <NUM>, <NUM>, as shown in the exemplary embodiment of <FIG>. For instance, a gap of about <NUM>" may be provided between teeth <NUM>, <NUM> and corresponding pins <NUM>, <NUM>, <NUM> under normal conditions, such as when joint <NUM> is not subjected to a lateral force and/or torque. In such a configuration, projections <NUM>, <NUM> may be used to bear compressive loads between discs <NUM>, <NUM> because teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> may not be in contact to bear compressive loads. According to another embodiment, teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> of the joint <NUM> of <FIG> may be in contact with one another when teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> are engaged. As a result, teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> may serve as bearing surfaces for a compressive load. In a configuration in which teeth and pins act as bearing surfaces, bearing projections may be omitted as load bearing surfaces, according to an exemplary embodiment, due to the teeth and pins acting as load bearing surfaces. As noted above, teeth <NUM>, <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM>, <NUM>, <NUM> in the exemplary embodiments of <FIG> may themselves serve as load bearing surfaces without additional load bearing projections.

Joint members may include various other design features other than those discussed in the exemplary embodiments above. For instance, with reference to <FIG> and <FIG>, joint feature <NUM> of disc <NUM> may form a shoulder <NUM> relative to a body <NUM> of disc <NUM> and joint feature <NUM> of disc <NUM> may include a projection <NUM> that forms a shoulder <NUM> relative to a body <NUM> of disc <NUM>, as shown in the exemplary embodiment of <FIG> and <FIG>. For instance, joint feature <NUM> may be located on a projection <NUM> that forms shoulder <NUM> relative to a body <NUM> of disc <NUM> and joint feature <NUM> may be located on a projection <NUM> that forms shoulder <NUM> relative to body <NUM> of disc <NUM>. Shoulders <NUM>, <NUM> may form an approximate right angle relative to body <NUM>, <NUM>. Bodies <NUM>, <NUM> of discs <NUM>, <NUM> may respectively include sloped surfaces <NUM>, <NUM> that may engage one another when discs <NUM>, <NUM> are rotated relative to one another to the limit of the range of motion between discs <NUM>, <NUM>, as shown in <FIG> and <FIG>. Thus, sloped surfaces <NUM>, <NUM> may serve as stops limiting rotation between discs <NUM>, <NUM>.

Also, teeth and/or tooth recesses may be relatively large and configured to provide a large degree of surface contact when intermeshed. In contrast to the use of a larger number of small teeth which can be more easily disengaged by a side load, this large surface contact can assist to minimize slippage between discs, such as under relatively high side loads. The large surface contact also minimizes rotation (in contrast to roll) between discs such as rotation about a longitudinal axis of a joint. Thus by minimizing slippage between the bearing surfaces of the discs, and relative axial rotation of the discs, the wrist can be used at large angles (e.g., more than <NUM> degrees and up to <NUM>-degrees, depending on the roll angle limit of an individual configuration) without the two discs disengaging from one another under loads experienced during surgery.

According to another exemplary embodiment, a joint <NUM> may include discs <NUM>, <NUM> that do not have shoulders or projections from a disc body that form a shoulder, as shown in <FIG>. Disc <NUM> may include teeth <NUM>, <NUM> that extend from a sloped surface <NUM> on the side of disc <NUM> instead of a shoulder. Similarly, disc <NUM> may include pins <NUM>, <NUM>, <NUM> that extend from a sloped surface <NUM> on the side of disc <NUM>. For instance, teeth <NUM>, <NUM> may extend directly from sloped surface <NUM> and pins <NUM>, <NUM>, <NUM> may extend directly from sloped surface <NUM>. Discs <NUM>, <NUM> may include other features discussed above for the discs <NUM>, <NUM> of the exemplary embodiments of <FIG> and <FIG>, such as projections <NUM>, <NUM> and recesses <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

As shown and discussed above with reference to the exemplary embodiment of <FIG>, bearing projections <NUM>, <NUM> of discs <NUM>, <NUM> may be located closer to central aperture <NUM> than pins <NUM>, <NUM>, <NUM> and teeth <NUM>, <NUM> along a radial direction, respectively. Such a configuration may lead to openings <NUM> between teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> when discs <NUM>, <NUM> are rotated relative to one another, as shown in <FIG>. If joint <NUM> is used in a wrist or other component of a surgical instrument where discs <NUM>, <NUM> are exposed to a surrounding environment, it may be desirable to design discs <NUM>, <NUM> to minimize or eliminate openings between teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM>, even for relatively large rotation of the discs <NUM>, <NUM>. For instance, openings <NUM> between teeth and pins may permit materials from the surrounding environment to enter in opening <NUM>, which can potentially hinder articulation of the joint.

Turning to <FIG>, an exemplary embodiment of a joint <NUM> is shown that includes a first disc <NUM> and a second disc <NUM>. Disc <NUM> may include a tooth <NUM> and disc <NUM> may include pins <NUM>, <NUM>. According to an exemplary embodiment, a recess <NUM> of disc <NUM> configured to accommodate tooth <NUM> may have a trochoid shape to minimize or eliminate openings between teeth and pins. As shown in the exemplary embodiment of <FIG>, tip <NUM> of tooth <NUM> may trace a curve <NUM> as first disc <NUM> and second disc <NUM> are rotated relative to one another, with the ends of curve <NUM> extended beyond the physical range of motion limits between discs <NUM>, <NUM> so that the shape of curve <NUM> is more apparent. By using a recess <NUM> with a trochoid surface in a joint <NUM>, an opening between tooth <NUM> and recess <NUM> can be minimized or eliminated, particularly when joint <NUM> includes a single tooth <NUM>. When a joint includes multiple teeth, such as in the exemplary embodiments of <FIG>, a gap or other misalignment may still occur between the teeth and pins, particularly when the joint is actuated to large ranges of motion.

Turning to <FIG>, which shows an enlarged view of area <NUM> after discs <NUM>, <NUM> have been rotated relative to one another in direction <NUM> in <FIG> to their fullest extent, tooth <NUM> remains engaged with a surface of recess <NUM>. For instance, tip <NUM> of tooth <NUM> may remain received within recess <NUM>, as shown in <FIG>, particularly when joint <NUM> includes a small number of teeth. Further, a gap between tooth <NUM> and pins <NUM>, <NUM> (and also between tooth <NUM> and the surface of recess <NUM>) may remain small, such as when tooth <NUM> and pins <NUM>, <NUM> do not contact one another under normal conditions (e.g., when no lateral force and/or torque is applied to joint <NUM>), thus minimizing or eliminating openings between tooth <NUM> and pins <NUM>, <NUM> in which materials from a surrounding environment could enter when discs <NUM>, <NUM> rotate back toward a neutral position.

Another method of addressing openings between teeth and pins is to reduce the exposure of openings between teeth and pins to a surrounding environment. In the exemplary embodiment of <FIG>, bearing projections <NUM>, <NUM> of discs <NUM>, <NUM> may be radially inward to pins <NUM>, <NUM>, <NUM> and teeth <NUM>, <NUM>, respectively, relative to central aperture <NUM>. As a result, teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> are located on a periphery of discs <NUM>, <NUM> and openings <NUM> between teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM>, such as when discs <NUM>, <NUM> are rotated relative to one another, may be exposed to a surrounding environment. In another exemplary embodiment, bearing projections may be located at a greater radial distance from a central projection than teeth or pins.

Turning to <FIG>, an exemplary embodiment of a joint <NUM> is shown that includes a first disc <NUM> and a second disc <NUM>. Disc <NUM> may include teeth <NUM>, <NUM> and a bearing projection <NUM>, as described above for the exemplary embodiment of <FIG>, but with bearing projection <NUM> at an outboard location relative to teeth <NUM>, <NUM>. For instance, bearing projection <NUM> may be located at a greater radial distance from central aperture <NUM> than teeth <NUM>, <NUM>. Disc <NUM> may include pins <NUM>, <NUM>, <NUM> and a bearing projection <NUM>, as described above for the exemplary embodiment of <FIG>, but with bearing projection <NUM> located at an outboard location relative to pins <NUM>, <NUM>, <NUM>. For instance, bearing projection <NUM> may be located at a greater radial distance from central aperture <NUM> of disc <NUM> than pins <NUM>, <NUM>, <NUM>. As a result, teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> are not located on an outer periphery of discs <NUM>, <NUM> and bearing projections <NUM>, <NUM> may shield teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> to a degree so that openings between teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> are less exposed to a surrounding environment in comparison to the exemplary embodiment of <FIG>.

According to an exemplary embodiment, projections <NUM>, <NUM> of discs <NUM>, <NUM> may include tendon passages to permit tendons to pass through discs <NUM>, <NUM>, such as tendon passages <NUM>, <NUM>, <NUM> shown in the exemplary embodiment of <FIG>. Turning to <FIG>, an exemplary embodiment of a joint <NUM> including discs <NUM>, <NUM> is shown, which may be configured according to the exemplary embodiment of <FIG>. Discs <NUM>, <NUM> may respectively include bearing projections <NUM>, <NUM>. Because bearing projections <NUM>, <NUM> are located at an outboard location relative to central apertures <NUM>, <NUM> (bearing projections <NUM>, <NUM> may be located radially outward and proximate to a periphery of discs <NUM>, <NUM>), drive tendons <NUM> extending through passages in bearing projections <NUM>, <NUM> also are located at an outboard location. Because drive tendons <NUM> are located at the periphery of discs <NUM>, <NUM> and extend between discs <NUM>, <NUM>, tendons <NUM> can provide a barrier to materials from a surrounding environment and reduce or eliminate the entry of such materials into openings between the teeth and pins of discs <NUM>, <NUM>.

One consideration for disc embodiments that include teeth and pins located at a radially inward location relative to a bearing projection that provides a loading surface is the ease of manufacturing the disc. For instance, positioning the teeth and pins radially inward of the bearing projections can pose manufacturing challenges, such as when molding or machining the discs, in comparison to disc embodiments in which teeth and pins are located at a radially outward location relative to a bearing projection. In view of this consideration, various exemplary embodiments contemplate discs for a joint that are configured to facilitate manufacture of the disc, including, for example, discs that include teeth or pins at an inward radial location relative to a projection and a central aperture.

As shown in <FIG>, a joint <NUM> that includes a first disc <NUM> having teeth <NUM>, <NUM> and a second disc <NUM> having pins <NUM>, <NUM>, <NUM>, according to an exemplary embodiment. The configuration shown in the exemplary embodiment of <FIG> may be used in the exemplary embodiments of <FIG>, <FIG>, and <FIG>. Teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> are configured to engage one another when joint <NUM> is in the neutral position shown in <FIG> and as discs <NUM>, <NUM> roll relative to one another. Circular arcs (represented by dashed lines) <NUM>, <NUM> represent contact surfaces (bearing surfaces) between discs <NUM>, <NUM>. Circular arcs <NUM>, <NUM> represent a rolling surface of motion of the discs, which corresponds to a theoretical arc through the points of contact between the pins and gears. Thus, circular arcs <NUM>, <NUM> may correspond to contact surfaces (bearing surfaces) between discs <NUM>, <NUM>. For instance, when discs <NUM>, <NUM> include bearing projections, such as bearing projections <NUM>, <NUM> of the exemplary embodiment of <FIG>, and the bearing projections have a shape of a partial cylinder, circular arcs <NUM>, <NUM> correspond to the cylindrical bearing surface. Circular arcs <NUM>, <NUM>, for instance, may be projections of surfaces of bearing projections <NUM>, <NUM>, <NUM>, <NUM> discussed above with regard to the exemplary embodiments of <FIG> and <FIG> onto a plane of pins <NUM>, <NUM>, <NUM>. The plane of pins <NUM>, <NUM>, <NUM> may be, for example, the plane of the page of <FIG>. For instance, circular arcs <NUM>, <NUM> may follow the contour of the load bearing surface of a bearing projection and indicate the position of pins <NUM>, <NUM>, <NUM> relative to the load bearing surface (e.g., adjacent the load bearing surface). Thus, circular arcs <NUM>, <NUM> may trace a load bearing surface of a bearing projection of a respective disc. In other words, although pins <NUM>, <NUM>, <NUM> may be offset from bearing projections in a radial direction of joint <NUM>, as shown in the exemplary embodiments of <FIG> and <FIG>, centers <NUM>, <NUM>, <NUM> of pins <NUM>, <NUM>, <NUM> may extend in direction <NUM> to substantially the same extent as a bearing projection of disc <NUM>. As a result, discs <NUM>, <NUM> may roll relative to one another in directions <NUM> as though discs <NUM>, <NUM> act as two circles (represented by circular arcs <NUM>, <NUM>) rolling against one another. In particular, the respective centers <NUM>, <NUM>, <NUM> of pins <NUM>, <NUM>, <NUM> lie on circular arc <NUM>. For instance, in the neutral position (e.g., at a zero angle roll alignment) shown in <FIG>, joint <NUM> is straight so that a longitudinal axis <NUM> passes through centers of both of discs <NUM>, <NUM>. Further, when discs <NUM>, <NUM> are rotated relative to one another in direction <NUM>, centers <NUM>, <NUM>, <NUM> of pins <NUM>, <NUM>, <NUM> may remain on circular arc <NUM> because the distance between pin centers <NUM>, <NUM>, <NUM> and circular arc <NUM> does not substantially change.

As shown in <FIG>, teeth <NUM>, <NUM>, the recess/depression <NUM> between the teeth, and the side cutouts/recesses <NUM> on the opposite sides of each tooth <NUM>,<NUM> act as a mechanical timing feature on the first disc. Similarly, pin/projection <NUM>, the side pins/projections <NUM>, <NUM>, along with the recesses/depressions between the pins/projections <NUM>, <NUM> and <NUM>, <NUM> act as a mechanical timing feature on the second disc. In the context of the disclosed embodiments, timing refers to mechanical indexing of motion between the two discs, which are components of a wrist or similar structure, so that the angular roll relation between the two components may be precisely controlled and known after a control input is made to change the angular roll relation to a desired value. Thus, various implementations of such timing features are disclosed.

According to an exemplary embodiment, a joint may be configured to have half of the range of motion of joint <NUM>. For example, a joint may be configured similarly to joint <NUM> in the exemplary embodiment of <FIG> but have only half of the structure of joint <NUM>, such as, for example, only the structures to the left of longitudinal axis <NUM> or to the right of longitudinal axis <NUM>. Thus, if the joint has only the structures to the left of longitudinal axis <NUM> in <FIG>, the joint may rotate to the left of longitudinal axis <NUM> along directions <NUM>, with motion stopping when joint is straight (such as discs <NUM>, <NUM> in <FIG>) so that the joint has half of the range of motion of joint <NUM>. Similarly, if the joint has only structure to the right of longitudinal axis <NUM> in <FIG>, the joint may rotate to the right of longitudinal axis <NUM> along directions <NUM>, with motion stopping when the joint is straight.

To enhance the timing of joint <NUM> and the smoothness of motion of joint <NUM>, teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> may extend along a radial direction <NUM> so that teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> engage and intermesh to a large degree when joint <NUM> is articulated, such as by rotating discs <NUM>, <NUM> relative to one another. As a result, as shown in <FIG>, pin <NUM> extends into a recess <NUM> located between teeth <NUM>, <NUM> so that teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> may engage and intermesh with one another to a large degree. To facilitate a large range of motion (rotation) between discs <NUM>, <NUM> in such an embodiment with a high degree of engagement and intermeshing between teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM>, cutouts <NUM> may be provided in the sides of a stem <NUM> to which pin <NUM> is connected, as shown in <FIG>. As a result, when discs <NUM>, <NUM> are rotated relative to one another along directions <NUM> and pin <NUM> and one of teeth <NUM> or <NUM> move towards one another, one of the respective sides <NUM>, <NUM> of teeth <NUM>, <NUM> may be received within a cutout <NUM> of pin <NUM> to provide a high range of motion for joint <NUM>. Further, cutouts <NUM> may be located laterally to teeth <NUM>, <NUM>, such as adjacent to the base of teeth <NUM>, <NUM>, to accommodate pins <NUM>, <NUM> at high ranges of motion when discs <NUM>, <NUM> are rotated relative to one another. A shoulder <NUM> of disc <NUM> may engage with a portion of disc <NUM>, such as part of pin <NUM> or <NUM>, and act as a mechanical stop, as will be discussed below.

As discussed above with regard to the exemplary embodiment of <FIG> and <FIG>, actuation of joint <NUM> can result in a tooth disengaging from corresponding pins so as to be removed from the tooth recess between the corresponding pins. <FIG> depicts joint <NUM> during motion of joint <NUM>, such as via rotation of disc <NUM>, <NUM> relative to one another along the counterclockwise direction of arrows <NUM>. While the range of motion depicted in <FIG> is counterclockwise, those having ordinary skill in the art will appreciate that the motions described would also apply to movement in the clockwise direction of <NUM>. Thus, in the symmetrical profiles illustrated in <FIG> and various other embodiments depicted, the range of motion includes a +/(clockwise/counterclockwise) range with respect to the longitudinal axis of the wrist structure. However, wrist joints may also be configured to move in only one direction relative to the longitudinal axis and thus only half of the joint structures (for example, either to the left or the right side of the axis <NUM> depicted in <FIG>) could be provided.

As shown in <FIG>, actuation of joint <NUM> to roll as depicted causes tooth <NUM> to extend further into recess <NUM> of disc <NUM> between pins <NUM> and <NUM> as discs <NUM>, <NUM>. Conversely, tooth <NUM> begins to withdraw from recess <NUM> and disengage from pins <NUM> and <NUM>. The disengagement of tooth <NUM> from recess <NUM> between pins <NUM> and <NUM> progresses as joint <NUM> continues to rotate, as shown in <FIG> and <FIG>, which show tooth <NUM> completely removed, or disengaged, from recess <NUM> and from pins <NUM> and <NUM>. As shown in <FIG>, articulation of joint <NUM> stops once joint <NUM> has reached its full range of motion (roll limit angle), at which point tooth <NUM> is completely removed from recess between pins <NUM> and <NUM>, at least a portion (the majority of in the embodiment of <FIG>) of tooth <NUM> remains within recess <NUM> between pins <NUM> and <NUM>, and pin <NUM> engages shoulder <NUM> of disc <NUM>, which acts as a mechanical stop to assist with stopping articulation and supporting the position of the joint <NUM> in its extreme range of motion position.

As discussed above with regard to <FIG>, discs <NUM>, <NUM> may include cutouts <NUM>, <NUM> to facilitate a large range of motion (rotation) between discs <NUM>, <NUM>. Cutouts <NUM>, <NUM>, however, may be difficult to manufacture, in particular, if disc <NUM> is manufactured by a molding process, because it is difficult to form the cutouts <NUM>, <NUM> with mold surfaces and then subsequently withdraw the mold surfaces from cutouts <NUM>, <NUM> due to the shape of cutouts <NUM>, <NUM> relative to adjacent components of discs <NUM>, <NUM>, particularly when teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> are located radially inward of bearing projections, such as in the exemplary embodiment of <FIG>. In addition, when teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> are located at a radially inward location, such as in the exemplary embodiment of <FIG>, the inward location makes machining of teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> challenging.

To enhance the ease of manufacturing joint discs, joint discs may be designed with a shape having fewer cutouts or even no cutouts. Turning to <FIG>, a side view of a joint <NUM> is shown that includes a first disc <NUM> with teeth <NUM>, <NUM> and a second disc <NUM> with pins <NUM>, <NUM>, <NUM>, according to an exemplary embodiment. Circular arcs (represented by dashed lines) <NUM>, <NUM> represent contact surfaces between discs <NUM>, <NUM>. For instance, circular arcs <NUM>, <NUM> may be projections of surfaces of bearing projections <NUM>, <NUM>, <NUM>, <NUM> discussed above with regard to the exemplary embodiments of <FIG> and <FIG>, similar to circular arcs <NUM>, <NUM>. Thus, discs <NUM>, <NUM> may rotate relative to one another in directions <NUM> as though discs <NUM>, <NUM> act as two circles (represented by circular arcs <NUM>, <NUM>) rolling against one another.

In the exemplary embodiment of <FIG>, teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> are shaped to extend along radial direction <NUM> to a lesser extent than in the exemplary embodiment of <FIG>. As a result, pin centers <NUM>, <NUM>, <NUM> are offset from circular arc <NUM>. For instance, in the neutral position shown in <FIG>, joint <NUM> is straight so that a longitudinal axis <NUM> passes through centers of both of discs <NUM>, <NUM>. Pin centers <NUM>, <NUM>, <NUM>, for example, may be offset from circular arc <NUM> by extending toward disc <NUM> along radial direction <NUM> (which may be a radial direction toward a center of circular arc <NUM>) a lesser amount than the bearing projection represented by circular arc <NUM>. Centers <NUM>, <NUM>, <NUM> of pins <NUM>, <NUM>, <NUM> may remain on arc <NUM> when joint <NUM> is articulated. Thus, when discs <NUM>, <NUM> are rotated relative to one another in direction <NUM>, centers <NUM>, <NUM>, <NUM> of pins <NUM>, <NUM>, <NUM> may remain on circular arc <NUM> because the distance between pin centers <NUM>, <NUM>, <NUM> and circular arc <NUM> does not substantially change. Because teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> extend to a lesser degree along radial direction <NUM>, sides <NUM> of stem <NUM> may be substantially straight with no undercuts. In addition, locations <NUM> lateral to teeth <NUM>, <NUM> may also lack cutouts, such as cutouts <NUM> in the exemplary embodiment of <FIG>. Thus, discs <NUM>, <NUM> may be easier to manufacture due to fewer cutouts or a lack of undercuts, thereby minimizing or eliminating surface contours that prevent a mold surface from being withdrawn, such as due to interlocking surfaces.

However, because teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> extend to a lesser extent along radial direction <NUM>, teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> engage and intermesh to a lesser extent, such as in comparison to the exemplary embodiment of <FIG>. As a result, articulation of joint <NUM> may be less smooth, such as when discs <NUM>, <NUM> are rotated relative to one another in direction <NUM>. Further, the degree of timing provided by teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> may be diminished in comparison to a joint having greater engagement between teeth and pins, such as in the exemplary embodiment of <FIG>.

In view of these considerations, it may be desirable to provide a joint that provides a balance between ease of manufacturing a joint and engagement between teeth and pins of the joint. Turning to <FIG>, a side view is shown of an exemplary embodiment of a joint <NUM> that includes a first disc <NUM> having teeth <NUM>, <NUM> and a second disc <NUM> having pins <NUM>, <NUM>, <NUM>. Circular arcs (represented by dashed lines) <NUM>, <NUM> represent contact surfaces between discs <NUM>, <NUM>. For instance, circular arcs <NUM>, <NUM> may be projections of surfaces of bearing projections <NUM>, <NUM>, <NUM>, <NUM> discussed above with regard to the exemplary embodiments of <FIG> and <FIG>, similar to circular arcs <NUM>, <NUM>. Thus, discs <NUM>, <NUM> may rotate relative to one another in directions <NUM> as though discs <NUM>, <NUM> act as two circles (represented by circular arcs <NUM>, <NUM>) rolling against one another.

In the exemplary embodiment of <FIG>, pins <NUM>, <NUM> are configured to extend along radial direction <NUM> to a lesser extent so that pins <NUM>, <NUM> are offset from circular arc <NUM>, but pin <NUM> extends a larger amount along radial direction <NUM> than pins <NUM>, <NUM>. Because of this, the respective centers <NUM>, <NUM> of pins <NUM>, <NUM> are offset radially from circular arc <NUM> along radial direction <NUM> but the center <NUM> of pin <NUM> is located on circular arc <NUM>. In the neutral position shown in <FIG>, joint <NUM> is straight, for example, so that a longitudinal axis <NUM> passes through centers of both of discs <NUM>, <NUM>. Further, when discs <NUM>, <NUM> are rotated relative to one another in direction <NUM>, center <NUM> of pin <NUM> may remain on circular arc <NUM> because the distance between pin centers <NUM>, <NUM>, <NUM> and circular arc <NUM> does not substantially change. In addition, pin <NUM> may extend to be received in recess <NUM> located between teeth <NUM>, <NUM>. As a result, teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> engage and intermesh with one another to a greater extent than in the exemplary embodiment of <FIG>, which may provide smoother motion and enhanced timing in comparison to the exemplary embodiment of <FIG>. In addition, sides <NUM> of stem <NUM> from which pin <NUM> extends may lack undercuts and locations <NUM> lateral to teeth <NUM>, <NUM> may also lack undercuts, facilitating the manufacture of discs <NUM>, <NUM>. Thus, by providing a disc <NUM> including at least one pin that is axially offset from a circular arc <NUM> representing the contact surface between the disc <NUM> and a companion disc <NUM> of a joint <NUM> and at least one pin that is not offset from the circular arc <NUM>, a balance may be provided between ease of manufacture and engagement between teeth and pins, which affects smoothness of joint motion and joint "timing. " Although pin <NUM> is not offset from circular arc <NUM> and pins <NUM>, <NUM> are offset from circular arc <NUM> in the exemplary embodiment of <FIG>, other configurations may be used. For instance, a disc including four pins may have the two end pins offset from the circular arc representing a contact surface of the disc, while the two middle pins are not offset from the circular arc.

As described, for example with respect to the motions of the joint of <FIG>, it should be appreciated that teeth <NUM> and <NUM> of the exemplary embodiments of <FIG> and <FIG> also become removed/withdrawn from with their respective recesses depending on the direction of rotation of the discs during articulation of joints <NUM>, <NUM>. Further, the teeth of joints <NUM> and <NUM> may become disengaged from corresponding pins during articulation of joints <NUM>, <NUM>, as discussed above with regard to <FIG>. The sequence of <FIG> illustrates roll motion between two discs that include contact bearing surfaces and timing structures adjacent the contact bearing surfaces, as the discs roll from an aligned (zero angle) orientation to an example roll limit angle of about <NUM> degrees. As the two bearing surfaces roll against each other, the outer surfaces of the teeth and corresponding recesses slide past one another until the side of pin <NUM> jams against shoulder <NUM> and the outer surface of tooth <NUM> jams against the outer surface of pin <NUM> to act as roll angle limit stops. Either one of these jamming roll limit stops may be eliminated in some implementations, or both may be eliminated in other implementations in which a separate mechanical roll limit angle stop is used. In yet other implementations, a mechanical roll limit stop is not used, and the angular relationship between the two discs is controlled so that the angle does not exceed a defined angle that might cause the joint to disengage under anticipated loads.

Joints <NUM>, <NUM>, <NUM> of the exemplary embodiments of <FIG> may also include bearing projections (not shown), as described above in the exemplary embodiments of <FIG> and <FIG>, to bear compressive loads. As noted above, the bearing projections may provide surfaces represented by circular arcs <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. Such bearing projections may permit teeth and pins of joints <NUM>, <NUM>, <NUM> to remain spaced apart from one another. For instance, bearing projections included in joint <NUM> of the exemplary embodiment of <FIG> may permit teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> to be spaced from one another during normal circumstances (e.g., when a lateral force and/or torque is not applied to joint <NUM>), as indicated in the exemplary embodiment of <FIG>. Alternatively, the joints of the exemplary embodiments of <FIG> may lack bearing projections, with teeth and pins of the joints bearing compressive loads. In particular, joints <NUM> and <NUM> of <FIG> and <FIG> could lack projections, with teeth <NUM>, <NUM> and pins <NUM>, <NUM>, <NUM> of joint <NUM> bearing compressive loads and recess <NUM> and teeth <NUM>, <NUM> bearing compressive load with pin <NUM> of joint <NUM> when discs <NUM>, <NUM> are in the positions shown in the exemplary embodiment of <FIG>.

By utilizing a configuration in which one or more pins are offset from a circular arc, a shape of the pins and teeth may be altered. For instance, teeth <NUM>, <NUM> may be more asymmetrically shaped than teeth <NUM>, <NUM> in the exemplary embodiment of <FIG> (in which pin centers <NUM>, <NUM>, <NUM> lie on circular arc <NUM>), with a first side <NUM> of tooth <NUM> following a curvature different than second side <NUM> of tooth <NUM>. Asymmetrically shaped teeth can affect the engagement between teeth and pins, as well as the reduction or elimination of cutouts. Turning to <FIG>, an exemplary embodiment of a disc <NUM> is shown, with line <NUM> outlining a shape of teeth <NUM>, <NUM> when corresponding pins (not shown) are offset from a circular arc, such as in the exemplary embodiment of <FIG>. In contrast, line <NUM> represents the shape of teeth <NUM>, <NUM> when corresponding pins (not shown) are not offset from a circular arc, such as in the exemplary embodiment of <FIG>. When some pins are offset and some are not, such as in the exemplary embodiment of <FIG>, teeth <NUM>, <NUM> may have a shape that is a hybrid of lines <NUM>, <NUM>. Lines <NUM>, <NUM> may be longitudinal axes of teeth <NUM>, <NUM> and may extend through tips <NUM> of teeth <NUM>, <NUM>, as shown in <FIG>. A comparison between lines <NUM>, <NUM> shows line <NUM> provides a more symmetrical shape for teeth <NUM>, <NUM> than line <NUM>. Further, line <NUM> reduces or eliminates cutouts <NUM> (indicated by line <NUM>), which would otherwise be located at lateral locations <NUM>. In addition, line <NUM> may result in a reduction of the amount that tooth tips <NUM> extend along direction <NUM>, in comparison to the tooth tips <NUM> provided by line <NUM>.

The exemplary embodiments and methods described herein have been described as being utilized with surgical and other instruments for teleoperated surgical systems. However, the exemplary embodiments and methods described herein may be used with other types of devices, such as laparoscopic instruments and other hand held instruments that use jointed motion.

Further modifications and alternative embodiments will be apparent to those of ordinary skill in the art in view of the disclosure herein. For example, the systems and the methods may include additional components or steps that were omitted from the diagrams and description for clarity of operation. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the present teachings. It is to be understood that the various embodiments shown and described herein are to be taken as exemplary. Elements and materials, and arrangements of those elements and materials, may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the present teachings may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of the description herein. Changes may be made in the elements described herein without departing from the scope of the present teachings and following claims.

It is to be understood that the particular examples and embodiments set forth herein are non-limiting, and modifications to structure, dimensions, materials, and methodologies may be made without departing from the scope of the present teachings.

Claim 1:
A medical instrument (<NUM>, <NUM>) comprising:
a wrist (<NUM>, <NUM>) comprising a first member (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and a second member (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) coupled in series at a joint (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), the first member and the second member articulatable relative to each other about the joint from a neutral position;
wherein the joint comprises:
a first joint feature (<NUM>, <NUM>) extending from the first member,
the first joint feature having a first end surface profile defining a central protrusion (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), a first outer protrusion (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), a second outer protrusion (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), a first recess (<NUM>, <NUM>), and a second recess (<NUM>, <NUM>), wherein the first recess and the second recess are on opposite sides of the central protrusion and between the first outer protrusion and the second outer protrusion, and wherein the central protrusion, the first outer protrusion, and the second outer protrusion have a rounded end surface profile, and
a second joint feature (<NUM>, <NUM>) extending from the second member,
the second joint feature having a second end surface profile defining a central recess (<NUM>, <NUM>, <NUM>, <NUM>), a first outer recess (<NUM>, <NUM>, <NUM>, <NUM>), a second outer recess (<NUM>, <NUM>, <NUM>, <NUM>), a first protrusion (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) between the first outer recess and the central recess, and a second protrusion (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) between the second outer recess and the central recess, and
wherein, in the neutral position of the wrist, the central protrusion of the first joint feature is received within the central recess of the second joint feature, and
wherein the first protrusion and the second protrusion have a tooth shaped end surface profile different from the rounded end surface profile of the first outer protrusion, the second outer protrusion, and the central protrusion, and different from the shape of the first recess and the second recess.