Patent Publication Number: US-2020275934-A1

Title: Reverse loading surgical clip applier

Description:
BACKGROUND 
     Minimally invasive surgical (MIS) tools and procedures are often preferred over traditional open surgical approaches due to their propensity toward reducing post-operative recovery time and leaving minimal scarring. Endoscopic surgery is one type of MIS procedure in which a surgical tool operably connected to an elongate shaft is introduced into the body of a patient through a natural bodily orifice. Laparoscopic surgery is a related type of MIS procedure in which a small incision is formed in the abdomen of a patient and a trocar is inserted through the incision to form a surgical access pathway for a surgical tool and elongate shaft. Once located within the abdomen, the surgical tool engages and/or treats tissue in a number of ways to achieve a diagnostic or therapeutic effect. Manipulation and engagement of the surgical tool may take place via various components passing through the elongate shaft. 
     One surgical instrument commonly used with a trocar is a surgical clip applier, which can be used to ligate blood vessels, ducts, shunts, or portions of body tissue during surgery. Traditional surgical clip appliers have a handle and an elongate shaft extending from the handle. A pair of movable opposed jaws is positioned at the end of the elongate shaft for holding and forming a surgical clip or “ligation clip” therebetween. In operation, a user (e.g., a surgeon or clinician) positions the jaws around the vessel or duct and squeezes a trigger on the handle to close the jaws and thereby collapse the surgical clip over the vessel. 
     More recently, however, robotic systems have been developed to assist in MIS procedures. Instead of directly engaging a surgical instrument, users are now able to manipulate and engage surgical instruments via an electronic interface communicatively coupled to a robotic manipulator. With the advances of robotic surgery, a user need not even be in the operating room with the patient during the surgery. 
     Robotic surgical systems are also now capable of utilizing robotically controlled clip appliers. Such clip appliers include features for robotically feeding and forming surgical clips. Advances and improvements to the methods and devices for applying surgical clips to vessels, ducts, shunts, etc. is continuously in demand to make the process more efficient and safe. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following figures are included to illustrate certain aspects of the present disclosure, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, without departing from the scope of this disclosure. 
         FIG. 1  is a block diagram of an example robotic surgical system that may incorporate some or all of the principles of the present disclosure. 
         FIG. 2  is an isometric top view of an example surgical tool that may incorporate some or all of the principles of the present disclosure. 
         FIG. 3  is an isometric bottom view of the surgical tool of  FIG. 2 . 
         FIG. 4  is an exploded view of the elongate shaft and the end effector of the surgical tool of  FIGS. 2 and 3 . 
         FIG. 5  is an exposed isometric view of the surgical tool of  FIG. 2 . 
         FIG. 6  is a side view of an example surgical tool that may incorporate some or all of the principles of the present disclosure. 
         FIG. 7  illustrates potential degrees of freedom in which the wrist of  FIG. 1  may be able to articulate (pivot). 
         FIG. 8  is an enlarged isometric view of the distal end of the surgical tool of  FIG. 6 . 
         FIG. 9  is a bottom view of the drive housing of the surgical tool of  FIG. 6 . 
         FIG. 10  is an isometric exposed view of the interior of the drive housing of the surgical tool of  FIG. 6 . 
         FIG. 11  is an enlarged isometric view of an example end effector. 
         FIGS. 12A-12D  are progressive isometric views of the end effector of  FIG. 11  during example loading operation. 
         FIGS. 13A-13B  are exposed, partial cross-sectional side views of the end effector of  FIG. 11  during example operation. 
         FIG. 14  is an isometric view of another example embodiment of the end effector of  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is related to surgical systems and, more particularly, to surgical clip appliers with jaws that are rotatable to feed surgical clips between opposed jaw members. 
     Embodiments discussed herein describe improvements to clip applier end effectors. The end effectors described herein include a body having a proximal end and a distal end, a clip cartridge coupled to the body and containing one or more surgical clips, and a head rotatably coupled to the distal end. First and second jaw members are mounted to the head such that rotation of the head correspondingly moves the first and second jaw members. The head may be rotatable between a loading position, where the first and second jaw members are aligned to receive a distal-most surgical clip of the one or more surgical clips, and a clamping position, where the first and second jaw members are positioned to crimp a surgical clip interposing the first and second jaw members. 
     In contrast to conventional clip appliers, the surgical clips may be received by the jaw members crown first, which helps mitigate catching the surgical clips on any sharp corners that might obstruct their distal advancement. Moreover, the presently described jaw members may comprise independent or separate plate-like structures that may prove advantageous in facilitating parallel closure of the jaw members, which can reduce the force required to crimp a surgical clip. 
       FIG. 1  is a block diagram of an example robotic surgical system  100  that may incorporate some or all of the principles of the present disclosure. As illustrated, the system  100  can include at least one master controller  102   a  and at least one arm cart  104 . The arm cart  104  may be mechanically and/or electrically coupled to a robotic manipulator and, more particularly, to one or more robotic arms  106  or “tool drivers”. Each robotic arm  106  may include and otherwise provide a location for mounting one or more surgical tools or instruments  108  for performing various surgical tasks on a patient  110 . Operation of the robotic arms  106  and instruments  108  may be directed by a clinician  112   a  (e.g., a surgeon) from the master controller  102   a.    
     In some embodiments, a second master controller  102   b  (shown in dashed lines) operated by a second clinician  112   b  may also direct operation of the robotic arms  106  and instruments  108  in conjunction with the first clinician  112   a . In such embodiments, for example, each clinician  102   a,b  may control different robotic arms  106  or, in some cases, complete control of the robotic arms  106  may be passed between the clinicians  102   a,b . In some embodiments, additional arm carts (not shown) having additional robotic arms (not shown) may be utilized during surgery on a patient  110 , and these additional robotic arms may be controlled by one or more of the master controllers  102   a,b.    
     The arm cart  104  and the master controllers  102   a,b  may be in communication with one another via a communications link  114 , which may be any type of wired or wireless telecommunications means configured to carry a variety of communication signals (e.g., electrical, optical, infrared, etc.) according to any communications protocol. 
     The master controllers  102   a,b  generally include one or more physical controllers that can be grasped by the clinicians  112   a,b  and manipulated in space while the surgeon views the procedure via a stereo display. The physical controllers generally comprise manual input devices movable in multiple degrees of freedom, and which often include an actuatable handle for actuating the surgical instrument(s)  108 , for example, for opening and closing opposing jaws, applying an electrical potential (current) to an electrode, or the like. The master controllers  102   a,b  can also include an optional feedback meter viewable by the clinicians  112   a,b  via a display to provide a visual indication of various surgical instrument metrics, such as the amount of force being applied to the surgical instrument (i.e., a cutting instrument or dynamic clamping member). 
     Example implementations of robotic surgical systems, such as the system  100 , are disclosed in U.S. Pat. No. 7,524,320, the contents of which are incorporated herein by reference. The various particularities of such devices will not be described in detail herein beyond that which may be necessary to understand the various embodiments and forms of the various embodiments of robotic surgery apparatus, systems, and methods disclosed herein. 
       FIG. 2  is an isometric top view of an example surgical tool  200  that may incorporate some or all of the principles of the present disclosure. The surgical tool  200  may be the same as or similar to the surgical instrument(s)  108  of  FIG. 1  and, therefore, may be used in conjunction with the robotic surgical system  100  of  FIG. 1 . Accordingly, the surgical tool  200  may be designed to be releasably coupled to a robotic arm  106  ( FIG. 1 ) of a robotic manipulator of the robotic surgical system  100 . Full detail and operational description of the surgical tool  200  is provided in U.S. Patent Pub. 2016/0287252, entitled “Clip Applier Adapted for Use with a Surgical Robot,” the contents of which are hereby incorporated by reference in their entirety. 
     While the surgical tool  200  is described herein with reference to a robotic surgical system, it is noted that the principles of the present disclosure are equally applicable to non-robotic surgical tools or, more specifically, manually operated surgical tools. Accordingly, the discussion provided herein relating to robotic surgical systems merely encompasses one example application of the presently disclosed inventive concepts. 
     As illustrated, the surgical tool  200  can include an elongate shaft  202 , an end effector  204  coupled to the distal end of the shaft  202 , and a drive housing  206  coupled to the proximal end of the shaft  202 . The terms “proximal” and “distal” are defined herein relative to a robotic surgical system having an interface configured to mechanically and electrically couple the surgical tool  200  (e.g., the drive housing  206 ) to a robotic manipulator. The term “proximal” refers to the position of an element closer to the robotic manipulator and the term “distal” refers to the position of an element closer to the end effector  204  and thus further away from the robotic manipulator. Moreover, the use of directional terms such as above, below, upper, lower, upward, downward, left, right, and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward or upper direction being toward the top of the corresponding figure and the downward or lower direction being toward the bottom of the corresponding figure. 
     In applications where the surgical tool  200  is used in conjunction with a robotic surgical system (e.g., system  100  of  FIG. 1 ), the drive housing  206  can include a tool mounting portion  208  designed with features that releasably couple the surgical tool  200  to a robotic arm (e.g., the robotic arms  106  or “tool drivers” of  FIG. 1 ) of a robotic manipulator. The tool mounting portion  208  may releasably attach (couple) the drive housing  206  to a tool driver in a variety of ways, such as by clamping thereto, clipping thereto, or slidably mating therewith. In some embodiments, the tool mounting portion  208  may include an array of electrical connecting pins, which may be coupled to an electrical connection on the mounting surface of the tool driver. While the tool mounting portion  208  is described herein with reference to mechanical, electrical, and magnetic coupling elements, it should be understood that a wide variety of telemetry modalities might be used, including infrared, inductive coupling, or the like. 
       FIG. 3  is an isometric bottom view of the surgical tool  200 . The surgical tool  200  further includes an interface  302  that mechanically and electrically couples the tool mounting portion  208  to a robotic manipulator. In various embodiments, the tool mounting portion  208  includes a tool mounting plate  304  that operably supports a plurality of drive inputs, shown as a first drive input  306   a , a second drive input  306   b , and a third drive input  306   c . While only three drive inputs  306   a - c  are shown in  FIG. 3 , more or less than three may be employed, without departing from the scope of the disclosure. 
     In the illustrated embodiment, each drive input  306   a - c  comprises a rotatable disc configured to align with and couple to a corresponding input actuator (not shown) of a given tool driver. Moreover, each drive input  306   a - c  provides or defines one or more surface features  308  configured to align with mating surface features provided on the corresponding input actuator. The surface features  308  can include, for example, various protrusions and/or indentations that facilitate a mating engagement. 
       FIG. 4  is an exploded view of one example of the elongate shaft  202  and the end effector  204  of the surgical tool  200  of  FIGS. 2 and 3 , according to one or more embodiments. As illustrated, the shaft  202  includes an outer tube  402  that houses the various components of the shaft  202 , which can include a jaw retaining assembly  404 . The jaw retaining assembly  404  includes a jaw retainer shaft  406  with a clip track  408  and a push rod channel  410  formed thereon. The end effector  204  includes opposing jaws  412  that are configured to mate to a distal end of the clip track  408 . 
     The shaft  202  also includes a clip advancing assembly, which, in one example embodiment, can include a feeder shoe  414  adapted to be slidably disposed within the clip track  408 . The feeder shoe  414  is designed to advance a series of clips  416  positioned within the clip track  408 , and a feedbar  418  is adapted to drive the feeder shoe  414  through the clip track  408 . An advancer assembly  420  is adapted to mate to a distal end of the feedbar  418  for advancing a distal-most clip into the jaws  412 . 
     The shaft  202  furthers include a clip forming or camming assembly operable to collapse the jaws  412  and thereby crimp (crush) a surgical clip  416  positioned between (interposing) the jaws  412 . The camming assembly includes a cam  422  that slidably mates to the jaws  412 , and a push rod  424  that moves the cam  422  relative to the jaws  412  to collapse the jaws  412 . A tissue stop  426  can mate to a distal end of the clip track  408  to help position the jaws  412  relative to a surgical site. 
     The jaw retainer shaft  406  is extendable within and couples to the outer tube  402  at a proximal end  428   a , and its distal end  428   b  is adapted to mate with the jaws  412 . The push rod channel  410  formed on the jaw retainer shaft  406  may be configured to slidably receive the push rod  424 , which is used to advance the cam  422  over the jaws  412 . The clip track  408  extends distally beyond the distal end  428   b  of the jaw retainer shaft  406  to allow a distal end of the clip track  408  to be substantially aligned with the jaws  412 . 
     The clip track  408  can include several openings  430  formed therein for receiving an upper or “superior” tang  432   a  formed on the feeder shoe  414  adapted to be disposed within the clip track  408 . The clip track  408  can also include a stop tang  434  formed thereon that is effective to be engaged by a corresponding stop tang formed on the feeder shoe  414  to prevent movement of the feeder shoe  414  beyond a distal-most position. To facilitate proximal movement of the feeder shoe  414  within the clip track  408 , the feeder shoe  414  can also include a lower or “inferior” tang  432   b  formed on the underside thereof for allowing the feeder shoe  414  to be engaged by the feedbar  418  as the feedbar  418  is moved distally. In use, each time the feedbar  418  is moved distally, a detent formed in the feedbar  418  engages the inferior tang  432   b  and moves the feeder shoe  414  distally a predetermined distance within the clip track  408 . The feedbar  418  can then be moved proximally to return to its initial position, and the angle of the inferior tang  432   b  allows the inferior tang  432   b  to slide into the next detent formed in the feedbar  418 . 
     The jaws  412  include first and second opposed jaw members that are movable (collapsible) relative to one another and are configured to receive a surgical clip from the series of clips  416  therebetween. The jaw members can each include a groove formed on opposed inner surfaces thereof for receiving the legs of a surgical clip  416  in alignment with the jaw members. In the illustrated embodiment, the jaw members are biased to an open position and a force is required to urge the jaw members toward one another to crimp the interposing clip  416 . The jaw members can also each include a cam track formed thereon for allowing the cam  422  to slidably engage and move the jaw members toward one another. A proximal end  436   a  of the cam  422  is matable with a distal end  438   a  of the push rod  424 , and a distal end  436   b  of the cam  422  is adapted to engage and actuate the jaws  412 . The proximal end  438   b  of the push rod  424  is matable with a closure link assembly associated with the drive housing  206  for moving the push rod  424  and the cam  422  relative to the jaws  412 . 
     The distal end  436   b  of the cam  422  includes a camming channel or tapering recess formed therein for slidably receiving corresponding cam tracks provided by the jaw members. In operation, the cam  422  is advanced from a proximal position, in which the jaw members are spaced apart from one another, to a distal position, where the jaw members are collapsed to a closed position. As the cam  422  is advanced over the jaw members, the tapering recess at the distal end  436   b  serves to push the jaw members toward one another, thereby crimping a surgical clip  416  disposed therebetween. 
       FIG. 5  is an exposed isometric view of the surgical tool  200  of  FIG. 2 , according to one or more embodiments. The shroud or covering of the drive housing  206  has been removed to reveal the internal component parts. As illustrated, the surgical tool  200  may include a first drive gear  502   a , a second drive gear  502   b , and a third drive gear  502   c . The first drive gear  502   a  may be operatively coupled to (or extend from) the first drive input  306   a  ( FIG. 3 ) such that actuation of the first drive input  306   a  correspondingly rotates the first drive gear  502   a . Similarly, the second and third drive gears  502   b,c  may be operatively coupled to (or extend from) the second and third drive inputs  306   b,c  ( FIG. 3 ), respectively, such that actuation of the second and third drive inputs  306   b,c  correspondingly rotates the second and third drive gears  502   b,c , respectively. 
     The first drive gear  502   a  may be configured to intermesh with a first driven gear  504   a , which is operatively coupled to the shaft  202 . In the illustrated embodiment, the driven gear  504   a  comprises a helical gear. In operation, rotation of the first drive gear  502   a  about a first axis correspondingly rotates the first driven gear  504   a  about a second axis orthogonal to the first axis to control rotation of the shaft  202  in clockwise and counter-clockwise directions based on the rotational direction of the first drive gear  502   a.    
     The second drive gear  502   b  may be configured to intermesh with a second driven gear  504   b  (partially visible in  FIG. 5 ), and the third drive gear  502   c  may be configured to intermesh with a third driven gear  504   c . In the illustrated embodiment, the second and third drive and driven gears  502   b,c ,  504   b,c  comprise corresponding rack and pinion interfaces, where the driven gears  504   b,c  comprise the rack and the drive gears  502   b,c  comprise the pinion. Independent rotation of the second and third drive gears  502   b,c  will cause the second and third driven gears  504   b,c , respectively, to translate linearly relative to (independent of) one another. 
     In at least one embodiment, actuation (rotation) of the third drive gear  502   c  will result in a surgical clip  416  ( FIG. 4 ) being fed into the jaws  412 . More particularly, the third driven gear  504   c  may be operatively coupled to the feedbar  418  ( FIG. 4 ) and, upon rotation of the third drive gear  502   c  in a first angular direction, the third driven gear  504   c  will advance distally and correspondingly advance the feedbar  418  a sufficient distance to fully advance a surgical clip into the jaws  412 . Rotation of the third drive gear  502   c  may be precisely controlled by an electrical and software interface to deliver the exact linear travel to the third driven gear  504   c  necessary to feed a clip  416  into the jaws  412 . 
     Upon delivery of a clip into the jaws  412 , or after a predetermined amount of rotation of the third drive gear  502   c , rotation of the third drive gear  502   c  is reversed in a second angular direction to move the third driven gear  504   c  linearly in a proximal direction, which correspondingly moves the feedbar  418  proximally. This process may be repeated several times to accommodate a predetermined number of clips residing in the shaft  202 . 
     Actuation of the second drive gear  502   b  causes the jaws  412  to close or collapse to crimp a surgical clip. More particularly, the second driven gear  504   b  may be coupled to the proximal end  438   b  ( FIG. 4 ) of the push rod  424  ( FIG. 4 ) and, upon actuation of the second drive gear  502   b  in a first angular direction, the second driven gear  504   b  will be advanced linearly in a distal direction and correspondingly drive the push rod  424  distally, which drives the cam  422  over the jaws  412  to collapse the jaw members and crimp a surgical clip positioned in the jaws  412 . Once a surgical clip is successfully deployed, rotation of the second drive gear  502   b  is reversed in the opposite angular direction to move the second driven gear  504   b  in a proximal direction, which correspondingly moves the push rod  424  and the cam  422  proximally and permits the jaws  412  to open once again. 
     The processes of delivering a surgical clip into the jaws  412  and collapsing the jaws  412  to crimp the surgical clip are not limited to the actuation mechanisms and structures described herein. In alternative embodiments, for example, the second and third driven gears  504   b,c  may instead comprise capstan pulleys configured to route and translate drive cables within the shaft  202 . In such embodiments, the drive cables may be operatively coupled to one or more lead screws or other types of rotating members positioned within the shaft  202  near the distal end and capable of advancing the feedbar  418  to deliver a surgical clip into the jaws  412  and advancing the cam  422  to collapse the jaws  412  and crimp the surgical clip. 
       FIG. 6  is an isometric top view of another example surgical tool  600  that may incorporate some or all of the principles of the present disclosure. Similar to the surgical tool  200  of  FIG. 2 , the surgical tool  600  may be used in conjunction with the robotic surgical system  100  of  FIG. 1 . As illustrated, the surgical tool  600  includes an elongate shaft  602 , an end effector  604  positioned at the distal end of the shaft  602 , a wrist  606  (alternately referred to as a “articulable wrist joint”) that couples the end effector  604  to the distal end of the shaft  602 , and a drive housing  608  coupled to the proximal end of the shaft  602 . In some embodiments, the shaft  602 , and hence the end effector  604  coupled thereto, is configured to rotate about a longitudinal axis A 1 . 
     In the illustrated embodiment, the end effector  604  comprises a clip applier that includes opposing jaw members  610 ,  612  configured to collapse toward one another to crimp a surgical clip. The wrist  606  comprises an articulatable joint that facilitates pivoting movement of the end effector  604  relative to the shaft  602  to position the end effector  604  at desired orientations and locations relative to a surgical site. The housing  608  includes (contains) various actuation mechanisms designed to control articulation and operation of the end effector  604 . 
       FIG. 7  illustrates the potential degrees of freedom in which the wrist  606  may be able to articulate (pivot). The degrees of freedom of the wrist  606  are represented by three translational variables (i.e., surge, heave, and sway), and by three rotational variables (i.e., Euler angles or roll, pitch, and yaw). The translational and rotational variables describe the position and orientation of a component of a surgical system (e.g., the end effector  604 ) with respect to a given reference Cartesian frame. As depicted in  FIG. 7 , “surge” refers to forward and backward translational movement, “heave” refers to translational movement up and down, and “sway” refers to translational movement left and right. With regard to the rotational terms, “roll” refers to tilting side to side, “pitch” refers to tilting forward and backward, and “yaw” refers to turning left and right. 
     The pivoting motion can include pitch movement about a first axis of the wrist  606  (e.g., X-axis), yaw movement about a second axis of the wrist  606  (e.g., Y-axis), and combinations thereof to allow for 360° rotational movement of the end effector  604  about the wrist  606 . In other applications, the pivoting motion can be limited to movement in a single plane, e.g., only pitch movement about the first axis of the wrist  606  or only yaw movement about the second axis of the wrist  606 , such that the end effector  604  moves only in a single plane. 
     Referring again to  FIG. 6 , the surgical tool  600  includes a plurality of drive cables (generally obscured in  FIG. 6 ) that form part of a cable driven motion system configured to facilitate operation and articulation (movement) of the end effector  604  relative to the shaft  602 . For example, selectively moving the drive cables can actuate the end effector  604  and thereby collapse the jaw members  610 ,  612  toward each other. Moreover, moving the drive cables can also move the end effector  604  between an unarticulated position and an articulated position. The end effector  604  is depicted in  FIG. 6  in the unarticulated position where a longitudinal axis A 2  of the end effector  604  is substantially aligned with the longitudinal axis A 1  of the shaft  602 , such that the end effector  604  is at a substantially zero angle relative to the shaft  602 . In the articulated position, the longitudinal axes A 1 , A 2  would be angularly offset from each other such that the end effector  604  is at a non-zero angle relative to the shaft  602 . 
       FIG. 8  is an enlarged isometric view of the distal end of the surgical tool  600  of  FIG. 6 . More specifically,  FIG. 8  depicts an enlarged and partially exploded view of the end effector  604  and the wrist  606 . The wrist  606  operatively couples the end effector  604  to the shaft  602 . To accomplish this, the wrist  606  includes a distal clevis  802   a , a proximal clevis  802   b , and a spacer  803  interposing the distal and proximal clevises  802   a,b . The end effector  604  is coupled to the distal clevis  802   a  and the distal clevis  802   a  is rotatably mounted to the spacer  803  at a first axle  804   a . The spacer  803  is rotatably mounted to the proximal clevis  802   b  at a second axle  804   b  and the proximal clevis  802   b  is coupled to a distal end  806  of the shaft  602 . 
     The wrist  606  provides a first pivot axis P 1  that extends through the first axle  804   a  and a second pivot axis P 2  that extends through the second axle  804   b . The first pivot axis P 1  is substantially perpendicular (orthogonal) to the longitudinal axis A 2  of the end effector  604 , and the second pivot axis P 2  is substantially perpendicular (orthogonal) to both the longitudinal axis A 2  and the first pivot axis P 1 . Movement about the first pivot axis P 1  provides “pitch” articulation of the end effector  604 , and movement about the second pivot axis P 2  provides “yaw” articulation of the end effector  604 . 
     A plurality of drive cables  808  extend longitudinally within the shaft  602  and pass through the wrist  106  to be operatively coupled to the end effector  604 . The drive cables  808  form part of the cable driven motion system briefly described above, and may be referred to and otherwise characterized as cables, bands, lines, cords, wires, ropes, strings, twisted strings, elongate members, etc. The drive cables  808  can be made from a variety of materials including, but not limited to, metal (e.g., tungsten, stainless steel, etc.) or a polymer. 
     The drive cables  808  extend proximally from the end effector  604  to the drive housing  608  ( FIG. 6 ) where they are operatively coupled to various actuation mechanisms or devices housed (contained) therein to facilitate longitudinal movement (translation) of the drive cables  808 . Selective actuation of the drive cables  808  causes the end effector  604  to articulate (pivot) relative to the shaft  602 . Moving a given drive cable  808  constitutes applying tension (i.e., pull force) to the given drive cable  808  in a proximal direction, which causes the given drive cable  808  to translate and thereby cause the end effector  604  to move (articulate) relative to the shaft  602 . 
     One or more actuation cables  810 , shown as first actuation cables  810   a  and second actuation cables  810   b , may also extend longitudinally within the shaft  602  and pass through the wrist  106  to be operatively coupled to the end effector  604 . The actuation cables  810   a,b  may be similar to the drive cables  808  and also form part of the cable driven motion system. Selectively actuating the actuation cables  810   a,b  causes the end effector  604  to actuate, such as collapsing the first and second jaw members  610 ,  612  to crimp a surgical clip (not shown). 
     More specifically, the actuation cables  810   a,b  may be operatively coupled to a cam  812  that is slidably engageable with the jaw members  610 ,  612 . One or more pulleys  814  may be used to receive and redirect the first actuation cables  810   a  for engagement with the cam  812 . Longitudinal movement of the first actuation cables  810   a  correspondingly moves the cam  812  distally relative to the jaw members  610 ,  612 . The distal end of the cam  812  includes a tapering recess or camming channel  816  formed therein for slidably receiving corresponding cam tracks  818  provided by the jaw members  610 ,  612 . As the cam  812  is advanced distally, the camming channel  816  pushes (collapses) the jaw members  610 ,  612  toward one another, thereby crimping a surgical clip (not shown) disposed therebetween. Actuation of the second actuation cables  810   b  (one shown) pulls the cam  812  proximally, thereby allowing the jaw members  610 ,  612  to open again to receive another surgical clip. 
     Although not expressly depicted in  FIG. 8 , an assembly including, for example, a feedbar, a feeder shoe, and a clip track may be included at or near the end effector  604  to facilitate feeding surgical clips into the jaw members  610 ,  612 . In some embodiments, the feedbar (or a connecting member) may be flexible and extend through the wrist  606 . 
       FIG. 9  is a bottom view of the drive housing  608 , according to one or more embodiments. As illustrated, the drive housing  608  may include a tool mounting interface  902  used to operatively couple the drive housing  608  to a tool driver of a robotic manipulator. The tool mounting interface  902  may mechanically, magnetically, and/or electrically couple the drive housing  608  to a tool driver. 
     As illustrated, the interface  902  includes and supports a plurality of drive inputs, shown as drive inputs  906   a ,  906   b ,  906   c ,  906   d ,  906   e , and  906   f . Each drive input  906   a - f  may comprise a rotatable disc configured to align with and couple to a corresponding input actuator (not shown) of a tool driver. Moreover, each drive input  906   a - f  provides or defines one or more surface features  908  configured to align with mating features provided on the corresponding input actuator. The surface features  908  can include, for example, various protrusions and/or indentations that facilitate a mating engagement. 
     In some embodiments, actuation of the first drive input  906   a  may control rotation of the elongate shaft  602  about its longitudinal axis A 1 . Depending on the rotational actuation of the first drive input  906   a , the elongate shaft  602  may be rotated clockwise or counter-clockwise. In some embodiments, selective actuation of the second and third drive inputs  906   b,c  may cause movement (axial translation) of the actuation cables  810   a,b  ( FIG. 8 ), which causes the cam  812  ( FIG. 8 ) to move and crimp a surgical clip, as generally described above. In some embodiments, actuation of the fourth drive input  906   d  feeds a surgical clip into the jaw members  610 ,  612  ( FIG. 8 ). In some embodiments, actuation of the fifth and sixth drive inputs  906   e,f  causes movement (axial translation) of the drive cables  808  ( FIG. 8 ), which results in articulation of the end effector  604 . Each of the drive inputs  906   a - f  may be actuated based on user inputs communicated to a tool driver coupled to the interface  902 , and the user inputs may be received via a computer system incorporated into the robotic surgical system. 
       FIG. 10  is an isometric exposed view of the interior of the drive housing  608 , according to one or more embodiments. Several component parts that may otherwise be contained within the drive housing  608  are not shown in  FIG. 10  to enable discussion of the depicted component parts. 
     As illustrated, the drive housing  608  contains a first capstan  1002   a , which is operatively coupled to or extends from the first drive input  906   a  ( FIG. 9 ) such that actuation of the first drive input  906   a  results in rotation of the first capstan  1002   a . A helical drive gear  1004  is coupled to or forms part of the first capstan  1002   a  and is configured to mesh and interact with a driven gear  1006  operatively coupled to the shaft  602  such that rotation of the driven gear  1006  correspondingly rotates the shaft  602 . Accordingly, rotation of the helical drive gear  1004  (via actuation of the first drive input  906   a  of  FIG. 9 ) will drive the driven gear  1006  and thereby control rotation of the elongate shaft  602  about the longitudinal axis A 1 . 
     The drive housing  608  also includes second and third capstans  1002   b  and  1002   c  operatively coupled to or extending from the second and third drive inputs  906   b,c  ( FIG. 9 ), respectively, such that actuation of the second and third drive inputs  906   b,c  results in rotation of the second and third capstans  1002   b,c . The second and third capstans  1002   b,c  comprise capstan pulleys operatively coupled to the actuation cables  810   a,b  ( FIG. 8 ) such that rotation of a given capstan  1002   b,c  actuates (longitudinally moves) a corresponding one of the actuation cables  810   a,b . Accordingly, selective rotation of the second and third capstans  1002   b,c  via actuation of the second and third drive inputs  906   b,c , respectively, will cause movement (axial translation) of the actuation cables  810   a,b , which causes the cam  812  ( FIG. 8 ) to move and crimp a surgical clip. 
     The drive housing  608  further includes a fourth capstan  1002   d , which is operatively coupled to or extends from the fourth drive input  906   d  ( FIG. 9 ) such that actuation of the fourth drive input  906   d  results in rotation of the fourth capstan  1002   d . A spur gear  1008  is coupled to or forms part of the fourth capstan  1002   d  and is configured to mesh and interact with a rack gear (not shown) also contained within the drive housing  608 . The rack gear may be operatively coupled to a feedbar (or another connecting member) which facilitates operation of a feeder shoe and associated clip track to feed surgical clips into the jaw members  610 ,  612  ( FIGS. 6 and 8 ). Accordingly, rotation of the spur gear  1008  (via actuation of the fourth drive input  906   d ) will control the feedbar and thereby control loading of surgical clips into the jaw members  610 ,  612  as desired. 
     The drive housing  608  further contains or houses fifth and sixth capstans  1002   e  and  1002   f  operatively coupled to or extending from the fifth and sixth drive inputs  906   e,f  ( FIG. 9 ), respectively, such that actuation of the fifth and sixth drive inputs  906   e,f  results in rotation of the fifth and sixth capstans  1002   e,f . The fifth and sixth capstans  1002   e,f  comprise capstan pulleys operatively coupled to the drive cables  808  ( FIG. 8 ) such that rotation of a given capstan  1002   e,f  actuates (longitudinally moves) a corresponding one of the actuation cables  808 . Accordingly, selective rotation of the fifth and sixth capstans  1002   e,f  via actuation of the fifth and sixth drive inputs  906   e,f , respectively, will cause movement (axial translation) of the drive cables  808  and thereby articulate (pivot) the end effector  604  relative to the shaft  602 . 
     The surgical tools  200 ,  600  described herein above may incorporate and facilitate the principles of the present disclosure in improving feeding and/or forming of surgical clips in robotic clip appliers. Moreover, it is contemplated herein to combine some or all of the features of the surgical tools  200 ,  600  to facilitate operation of the embodiments described herein. Accordingly, example surgical tools that may incorporate the principles of the present disclosure may include geared actuators, capstan pulley and cable actuators, or any combination thereof, without departing from the scope of the disclosure. 
       FIG. 11  is an enlarged isometric view of an example end effector  1102 , according to one or more embodiments the present disclosure. The end effector  1102  may be similar in some respects to the end effectors  204  and  604  of  FIGS. 2 and 6 , respectively. Similar to the end effectors  204 ,  604 , for example, the end effector  1102  may be incorporated into either or both of the surgical tools  200 ,  600  described herein above. Moreover, the end effector  1102  may comprise a clip applier having opposed jaw members  1104  and  1106  configured to collapse toward one another to crimp a surgical clip. As described herein, the end effector  1102  may incorporate various component parts and actuatable mechanisms or features that facilitate the feeding of a surgical clip into the jaw members  1104 ,  1106  and collapsing the jaw members  1104 ,  1106  to crimp the surgical clip when desired. 
     As illustrated, the end effector  1102  includes an elongate body  1108  having a proximal end  1110   a  and a distal end  1110   b . In some embodiments, the proximal end  1110   a  may be operatively coupled to an elongate shaft of a surgical tool, such as the shaft  202  of the surgical tool  200  of  FIG. 2 . In other embodiments, however, the proximal end  1110   a  may be operatively coupled to an articulable wrist joint, such as the wrist  606  of the surgical tool  600  of  FIG. 6 . 
     The end effector  1102  includes a head  1112  positioned or otherwise included at the distal end  1110   b  of body  1108 . The head  1112  may be rotatably coupled to the body  1108  at a hinge or axle  1114 , and the jaw members  1104 ,  1106  may be incorporated into or otherwise form part of the head  1112  such that rotation of the head  1112  on the axle  1114  correspondingly moves the jaw members  1104 ,  1106  in the same angular direction. 
     A pivot axis P 1  extends through the axle  1114  and is substantially perpendicular to a longitudinal axis A 1  of the effector  1102 . The head  1112  may be pivotable about the pivot axis P 1  between a loading position, where the jaw members  1104 ,  1106  are positioned to receive a surgical clip, and a clamping position, where the jaw members  1104 ,  1106  are positioned and otherwise poised to clamp (crimp) a surgical clip at a desired location. As will be appreciated, the clamping position may be any angular position away from the loading position and relative to the longitudinal axis A 1  of the effector  1102  where the jaw members  1104 ,  1106  are able to properly crimp a surgical clip at a desired location. Accordingly, it is contemplated herein to deploy (crimp) a surgical clip at any angular location as long as it does not interfere with clip loading at the loading position. As will be appreciated, one advantage of the angular versatility of the head  1112  is that a user may be able to position the jaw members  1104 ,  1106  in a reverse position (i.e., retroflexion and/or retroflex articulation) relative to target tissue, which increases the maneuverability. 
     In some embodiments, the range of potential angular movement of the head  1112  may be about 180°. In such embodiments, the clamping position may comprise any angle between the loading position and 180° from the loading position. In practice, however, and to account for the loading position, the clamping position may comprise any angle between 0° and about 160° relative to the longitudinal axis A 1 . In other embodiments, however, the range of potential angular movement of the head  1112  may be 360°. In such embodiments, the head  1112  may be capable of pivoting through the loading position in either angular direction and the clamping position may comprise virtually any angle relative to the longitudinal axis A 1 . In embodiments where the head  1112  does not pivot through the loading position in either angular direction, and to account for the loading position, the clamping position may comprise any angle between 0° and about 160° in in either angular direction relative to the longitudinal axis A 1 . 
     The end effector  1102  further includes a clip cartridge  1116  coupled to the body  1108  proximal to the head  1112  and configured to house one or more surgical clips  1118  (one partially shown). In some embodiments, the clip cartridge  1116  may be removably coupled to the body  1108 , such as through the use of one or more mechanical fasteners (e.g., screws), an interference fit, a snap fit, any combination thereof, or the like. In such embodiments, the clip cartridge  1116  may be removed from the body  1108  when the supply of surgical clips  1118  is exhausted. The clip cartridge  1116  may then either be replaced with a new cartridge containing additional surgical clips, or additional surgical clips  1118  may be added to the clip cartridge  1116 , which may then be reattached to the body  1108  for further operation. In other embodiments, however, the clip cartridge  1116  may form an integral part of the body  1108 . In such embodiments, when the supply of surgical clips  1118  is exhausted the end effector  1102  may be replaced with a new end effector having a fresh supply of surgical clips. 
       FIGS. 12A-12D  depict progressive isometric views of the end effector  1102  during an example clip loading operation, according to one or more embodiments of the disclosure. In  FIG. 12A , the head  1112  is shown in the process of being moved or rotated (pivoted) about the pivot axis P 1  toward the loading position where the jaw members  1104 ,  1106  become aligned or substantially aligned with a distal-most surgical clip  1118  to be received by the jaw members  1104 ,  1106 . The distal-most surgical clip  1118  may be one of a plurality of surgical clips  1118  contained within the clip cartridge  1116 , or may alternatively be the only or last surgical clip  1118  contained within the clip cartridge  1116 . The means for actuating the head  1112  between the clamping and loading positions will be discussed in further detail below. 
     The clip cartridge  1116  may define an opening  1202  through which the surgical clips  1118  are discharged to be received by the jaw members  1104 ,  1106 . In some embodiments, as illustrated, the crown of the distal-most surgical clip  1118  may protrude a short distance through the opening  1202  prior to being discharged from the clip cartridge  1116 . In such embodiments, the opening  1202  may be slightly smaller than the dimensions of the surgical clip  1118  to prevent the surgical clip  1118  from prematurely or inadvertently advancing out of the clip cartridge  1116 . In other embodiments, however, the distal-most surgical clip  1118  may be contained wholly within the clip cartridge  1116  prior to being discharged from the clip cartridge  1116  via the opening  1202 . 
     In  FIG. 12B , the head  1112  is shown as having moved (pivoted) to the loading position where the jaw members  1104 ,  1106  are generally aligned with the distal-most surgical clip  1118 . In some embodiments, each jaw member  1104 ,  1106  can include a channel or groove  1206  (better seen in  FIG. 13A ) formed on opposed inner surfaces thereof for receiving the distal-most surgical clip  1118 . In such embodiments, the grooves  1206  may prove advantageous in helping to capture and maintain the surgical clip  1118  in a known position between the jaw members  1104 ,  1106 . In other embodiments, however, the grooves  1206  may be omitted and the distal-most surgical clip  1118  may instead be captured or held by the jaw members  1104 ,  1106  via an interference fit or the like. 
     In some embodiments, the end effector  1102  may include a hard stop  1208  configured to receive and stop pivoting motion of the head  1112  at the loading position. In at least one embodiment, the body  1108  of the end effector  1102  may provide or define the hard stop  1208 , but the hard stop  1208  may alternatively be a structure coupled to the body  1108 . The hard stop  1208  may prove advantageous in helping maintain consistent loading alignment for the surgical clips  1118 . In other embodiments, however, the hard stop  1208  may be omitted and the actuation mechanisms that facilitate pivoting movement of the head  1112  may be configured to precisely align the jaw members  1104 ,  1106  with the distal-most surgical clip  1118 . 
     The clip cartridge  1116  is depicted in  FIG. 12B  in phantom and thereby exposing a set  1204  of surgical clips  1118  that might be contained within the clip cartridge  1116 . While seven surgical clips  1118  are shown in the set  1204 , it will be appreciated that more or less than seven may be contained within the clip cartridge  1116 , without departing from the scope of the disclosure. Indeed, in at least one embodiment, the set  1204  may comprise a single surgical clip  1118 . 
     Each surgical clip  1118  includes a crown  1210  (alternately referred to as an “apex”) and a pair of legs  1212  extending longitudinally from the crown  1210 . As illustrated, the surgical clips  1118  are positioned end-to-end within the clip cartridge  1116  with the legs  1212  of the more distal surgical clips  1118  resting on the crown  1210  of the more proximal surgical clips  1118 . Accordingly, the surgical clips  1118  are arranged within the clip cartridge  1116  with the crown  1210  leading and the legs  1212  extending proximally therefrom. As a result, the surgical clips  1118  are fed crown  1210  first into the jaw members  1104 ,  1106 . In contrast, conventional robotic clip appliers typically feed surgical clips legs first into opposed jaw members. Surgical clips are commonly designed to exhibit a slight taper, where the angle of the legs  1212  extending from the crown  1210  converge. This helps facilitate wedging the clips into the jaws legs first. One disadvantage of this clip design is that it reduces the clip-to-jaw retention capability since the legs are more tapered than the jaw. This also reduces allowable tip width between the jaw members, which correspondingly limits the size of tissue that can be treated. 
     Feeding the surgical clips  1118  crown first  1210  into the jaw members  1104 ,  1106  advantageously helps mitigate the surgical clips  1118  from getting caught on any sharp corners or the like that might obstruct their distal advancement. In embodiments including the grooves  1206  ( FIGS. 12B and 13A ) defined on each jaw member  1104 ,  1106 , the legs  1212  may spring outward and seat themselves within the grooves  1206  after having exited the clip cartridge  1116  by bypassing the smaller-sized opening  1202 . Moreover, feeding the surgical clips  1118  crown first  1210  into the jaw members  1104 ,  1106  allows a clip design where the legs  1212  can diverge, which increases clip to jaw retention and maximizes the allowable tip width between the jaw members  1104 ,  1106 , and thereby increasing the size of tissue that can be treated. 
     In  FIG. 12C , the distal-most surgical clip  1118  has been advanced distally out of the clip cartridge  1116  and received by the jaw members  1104 ,  1106 . As the distal-most surgical clip  1118  is received by the jaw members  1104 ,  1106 , the penultimate surgical clip  1118  may correspondingly advance distally until its crown  1210  protrudes a short distance out of the opening  1202 . In other embodiments, however, the penultimate surgical clip  1118  may remain entirely contained within the clip cartridge  1116  when the distal-most surgical clip  1118  has been received by the jaw members  1104 ,  1106 , without departing from the scope of the disclosure. 
     Advancing the set  1204  of surgical clips  1118  distally to discharge the distal-most surgical clip  1118  from the clip cartridge  1116  may be accomplished by actuating (moving) a clip pusher  1210 . The clip pusher  1210  may comprise any type of structure capable of applying an axial load on the set  1204  and thereby moving the set  1204  distally. For example, the clip pusher  1210  may comprise any rigid or semi-rigid rod, shaft, or planar structure (e.g., an elongate strip-like structure), or any combination thereof. In the illustrated embodiment, the clip pusher  1210  comprises a type of planar pusher bar, but could alternatively comprise another rigid or semi-rigid structure. The clip pusher  1210  is depicted herein as merely one example, and those skilled in the art will readily appreciate that many different configurations of the clip pusher  1210  may be employed, without departing from the scope of the disclosure. 
     In the illustrated embodiment, the clip pusher  1210  is depicted as being in contact with the legs  1212  of the proximal-most surgical clip  1118 . Because of the end-to-end arrangement of the surgical clips  1118 , pushing the proximal-most surgical clip  1118  will correspondingly move the remaining surgical clips  1118  in the set  1204  in the same direction. In other embodiments, however, the clip pusher  1210  may be configured to engage any other portion of the proximal-most surgical clip  1118 . In yet other embodiments, the clip pusher  1210  may be configured to engage a combination of two or more surgical clips  1118  to apply the required axial load on the set  1204  to move the set  1204  distally, without departing from the scope of the disclosure. 
     The clip pusher  1210  may apply an axial load on the surgical clips  1118  sufficient to advance the set  1204  distally and discharge the distal-most surgical clip  1118  from the clip cartridge  1116  via the opening  1202 . In some embodiments, actuation and distal movement of the clip pusher  1210  may be precisely controlled to deliver the exact amount of force and linear travel necessary to push (force) the distal-most surgical clip  1118  through the smaller-sized opening  1202  and feed the distal-most surgical clip  1118  into the jaw members  1104 ,  1106 . 
     In some embodiments, the clip pusher  1210  may extend proximally to a drive housing (e.g., the drive housings  206 ,  606  of  FIGS. 2 and 6 , respectively), which may include a drive input and corresponding actuating mechanisms configured to actuate (move) the clip pusher  1210  as needed. In other embodiments, the clip pusher  1210  may be operatively coupled to or otherwise form part of a clip feeding assembly including, for example, a flexible or rigid feedbar (e.g., the feedbar  418  of  FIG. 4 ) that extends from the drive housing and is actuated to correspondingly move the clip pusher  1210  distally and proximally as desired. 
     In  FIG. 12D , the head  1112  is shown as having moved (pivoted) away from the loading position to a clamping position. As mentioned above, the clamping position for the head  1112  may be any angular position away from the loading position and relative to or aligned with the longitudinal axis A 1 . In the illustrated embodiment, for example, the head  1112  is depicted as being aligned or substantially aligned with the longitudinal axis A 1 , but could alternatively be angularly offset from the longitudinal axis A 1 . 
     The surgical clip  1118  received within the jaw members  1104 ,  1106  is now ready to be deployed to ligate desired body tissue, for example, a blood vessel, a duct, a shunt, etc. Once the jaw members  1104 ,  1106  are properly positioned around or at the desired body tissue, the end effector  1102  may be actuated to collapse the jaw members  1104 ,  1106  and thereby crimp the surgical clip  1118  onto the body tissue. 
     The foregoing process of shown and described with respect to  FIGS. 12A-12D  can be repeated until the remaining surgical clips  1118  are depleted from the clip cartridge  1116 , at which point the clip cartridge  1116  may be removed to add additional surgical clips  1118 . The restocked clip cartridge  1116  may then be reattached to the body  1108  for further operation. Otherwise, the end effector  1102  as a whole may be replaced with a clip cartridge stocked with additional clips. 
     Still referring to  FIG. 12D , in some embodiments, the end effector  1102  may further include one or more proximity sensors  1214  (one shown) configured to sense and/or detect adjacent body structures or tissue during operation. In the illustrated embodiment, the proximity sensor  1214  is depicted as being coupled to or positioned on the head  1112 , but might alternatively be positioned at other locations on the end effector  1102 . The sensor  1214  may prove advantageous in helping determine when the head  1112  may safely pivot between the clamping and loading positions without coming into contact or otherwise damaging sensitive body structures or tissue. 
     The sensor  1214  may be communicably coupled (wired or wirelessly) to a robotic controller (e.g., controllers  102   a,b  of  FIG. 1 ) operated by a user, and the user may be updated in real-time as to the position of the head  1112  relative to sensitive body tissue. The real-time updates will help the user safely pivot the head  1112  without contacting anything vital or obstructing its movement. 
       FIGS. 13A and 13B  are exposed, partial cross-sectional side views of the end effector  1102 , according to one or more embodiments. More specifically,  FIG. 13A  depicts the end effector  1102  prior to crimping a surgical clip  1118  between the jaw members  1104 ,  1106 , and  FIG. 13B  shows the end effector  1102  following actuation to collapse the jaw members  1104 ,  1106 . The end effector  1102  includes a rotational actuator  1302   a  operable to move (pivot) the head  1112  between the loading and clamping positions, and further includes a linear actuator  1302   b  operable to actuate the jaw members  1104 ,  1106  to crimp the surgical clip  1118 . 
     The rotational actuator  1302   a  may comprise any device or mechanism capable of or configured to pivot the head  1112  between the loading position and any clamping position. In the illustrated embodiment, the rotational actuator  1302   a  includes an articulation pulley  1304  mounted to the axle  1114  such that rotation of the articulation pulley  1304  correspondingly rotates the axle  1114 . A first drive cable  1306   a  may be routed around the articulation pulley  1304  to cause rotation of the articulation pulley  1304  when translated longitudinally. Since the head  1112  is operatively coupled to the axle  1114 , rotation of the articulation pulley  1304 , as acted upon by the first drive cable  1306   a , simultaneously causes the head  1112  to rotate in the same angular direction. 
     The first drive cable  1306   a  may be similar to the drive cables  808  of  FIG. 8 . Moreover, the first drive cable  1306   a  may extend from a drive housing (e.g., the drive housings  206 ,  606  of  FIGS. 2 and 6 , respectively) and may be operatively coupled to a corresponding actuating mechanism or device positioned within the drive housing and configured to cause longitudinal translation of the first drive cable  1306   a . In one embodiment, for example, the first drive cable  1306   a  may be operatively coupled to one or more capstan pulleys, such as any of the rotatable capstans  1002   a - f  of  FIG. 10 . In other embodiments, the first drive cable  1306   a  may be operatively coupled and otherwise extend from one or more translatable driven gears, such as the first and second driven gears  504   a,b  of  FIG. 5 . In yet other embodiments, the first drive cable  1306   a  may be operatively coupled to any combination of capstan pulley and driven gear, without departing from the scope of the disclosure. 
     The linear actuator  1302   b  may comprise any device or mechanism capable of or configured to move (collapse) the jaw members  1104 ,  1106  toward each other and thereby crimp the surgical clip  1118  disposed therebetween. In the illustrated embodiment, for example, the linear actuator  1302   b  includes a jaw pulley  1308 , a bevel gear assembly  1310  operatively coupled to the jaw pulley  1308 , and a threaded linear drive  1312  operatively coupled to the bevel gear assembly  1310 . Rotation of the jaw pulley  1308  may cause actuation of the bevel gear assembly  1310 , which, in turn, may cause actuation of the threaded linear drive  1312 , which operates to collapse and open the jaw members  1104 ,  1106 . 
     More specifically, the jaw pulley  1308  may be rotatably mounted to the axle  1114 , but loosely mounted such that rotation of the jaw pulley  1308  does not rotate or otherwise act on the axle  1114 . A second drive cable  1306   b  may be routed around the jaw pulley  1308  to cause rotation of the jaw pulley  1308 . Similar to the first drive cable  1306   a , the second drive cable  1306   b  may be similar to the drive cables  808  of  FIG. 8  and may extend from a drive housing (e.g., the drive housings  206 ,  606  of  FIGS. 2 and 6 , respectively) where it is operatively coupled to a corresponding actuating mechanism or device configured to cause longitudinal translation of the second drive cable  1306   b.    
     The bevel gear assembly  1310  may include a beveled drive gear  1314   a  coupled to or forming part of the jaw pulley  1308  and a corresponding beveled driven gear  1314   b  positioned to be driven (rotated) by the drive gear  1314   a . Moreover, the threaded linear drive  1312  may include a worm gear  1316  operatively coupled to or extending from the driven gear  1314   b , and a threaded gear plate  1318  that provides a female threading  1320  configured to threadably mate with or engage the helical threading defined on the worm gear  1316 . 
     Example operation of the rotational actuator  1302   a  and the linear actuator  1302   b  is now provided. To move (pivot) the head  1112  between any clamping position and the loading position, and otherwise about the pivot axis P 1 , the first drive cable  1306   a  may be translated (moved) in either longitudinal direction. Movement of the first drive cable  1306   a  rotates the articulation pulley  1304 , which correspondingly rotates the axle  1114  about the pivot axis P 1 . Since the head  1112  is operatively coupled to the axle  1114 , rotation of the axle  1114  will simultaneously cause the head  1112  to rotate in the same angular direction. The longitudinal movement of the first drive cable  1306   a  may be precisely controlled to place the jaw members  1104 ,  1106  in the loading position and to otherwise accurately align the jaw members  1104 ,  1106  with a distal-most surgical clip for loading. Likewise, longitudinal movement of the first drive cable  1306   a  may be precisely controlled to position or otherwise orient the head  1112  in a desired clamping position away from the loading position. 
     When it is desired to crimp the surgical clip  1118  positioned between the jaw members  1104 ,  1106 , the second drive cable  1306   b  may be translated (moved) in a first driving direction, as indicated by the arrows A ( FIG. 13B ). As the second drive cable  1306   b  translates, the jaw pulley  1308  and the drive gear  1314   a  are correspondingly rotated relative to the axle  1114 , and the drive gear  1314   a  transmits a rotational load to the driven gear  1314   b , which correspondingly rotates in a first angular direction, as indicated by the arrow B ( FIG. 13B ). As the driven gear  1314   b  rotates, the helical threading on the worm gear  1316  interacts with the female threading  1320  on the gear plate  1318  and thereby urges (drives) the gear plate  1318  in a first linear direction, as indicated by the arrow C ( FIG. 13B ). 
     As illustrated, the jaw members  1104 ,  1106  comprise independent or separate plate-like structures that are configured to move laterally relative to one another to collapse and crimp the surgical clip  1118 . Each jaw member  1104 ,  1106  may provide and otherwise define one or more angled slots  1322  that extend at an angle offset from the longitudinal axis A 1  of the end effector  1102 . While two angled slots  1322  are shown on each jaw member  1104 ,  1106 , it will be appreciated that more or less than two may be employed, without departing from the scope of the disclosure. The angled slots  1322  of each jaw member  1104 ,  1106  may extend at equal but opposite angles. More particularly, the slots  1322  of the first jaw member  1104  may extend at a positive angle relative to the longitudinal axis A 1 , while the slots  1322  of the second jaw member  1106  may extend at a negative angle of the same magnitude relative to the longitudinal axis A 1 . As a result, depending on the axial direction, the angled slots  1322  diverge from or converge toward each other along the longitudinal axis A 1  of the end effector  1102 . 
     As illustrated, one or more transition pins  1324  extend from the gear plate  1318  and extend through the angled slots  1322  of each jaw member  1104 ,  1106  when the jaw members  1104 ,  1106  are installed in the end effector  1102 . The jaw members  1104 ,  1106  may be positioned within the head  1112  such that they are prevented from moving axially relative to the head  1112 , but able to move laterally and thus collapse towards one another or open. As the rotating worm gear  1316  rotates, the gear plate  1318  correspondingly moves in the first linear direction C ( FIG. 13B ), which simultaneously moves the transition pins  1324  in the same direction. The transition pins  1324  slidingly engage the angled slots  1322  and, because of the oppositely angled configuration of the angled slots  1322 , the transition pins  1324  will urge the jaw members  1104 ,  1106  to transition (move) laterally with respect to each other, as indicated by the oppositely directed arrows D ( FIG. 13B ). As the jaw members  1104 ,  1106  collapse toward each other in the direction D, the surgical clip  1118  will be crimped or crushed therebetween. 
     The jaw members  1104 ,  1106  may be re-opened to receive another un-crimped surgical clip by reversing the foregoing procedure. More specifically, the second drive cable  1306   b  may be translated (moved) in a second driving direction opposite the first driving direction A, which will rotate the jaw pulley  1308  and the drive gear  1314   a  in the opposite direction relative to the axle  1114 , and the driven gear  1314   b  will correspondingly rotate in a second angular direction opposite the first angular direction B. Rotating the driven gear  1314   b  in the second angular direction will unthread the worm gear  1316  from the gear plate  1318 , which urges (drives) the gear plate  1318  in a second linear direction opposite the first linear direction C. As the gear plate  1318  moves in the second linear direction, the transition pins  1324  also move in the same direction within and slidingly engage the angled slots  1322 , which urges the jaw members  1104 ,  1106  to separate from each other in a direction opposite the direction D. 
     In some embodiments, as the head  1112  is rotated via actuation of the rotational actuator  1302   a , the bevel gear assembly  1310  may be affected and may inadvertently reverse rotate as driven gear  1314   b  walks along the drive gear  1314   a  in the direction of rotation of the head  1112 . To prevent the worm gear  1316  from unintentionally advancing caused by the bevel gear assembly  1310  reverse rotating during movement of the head  1112 , the bevel gear assembly  1310  may be actuated to compensate for the reverse rotation. More specifically, the second drive cable  1306   b  may be actuated to back rotate the jaw pulley  1308  and the coupled drive gear  1314   a  to cancel out inadvertent movement of the bevel gear assembly  1310  during movement of the head  1112 . As will be appreciated, such back rotation of the jaw pulley  1308  may be automated, such as through a software-driven application. 
     The independent or separate plate-like structures of the jaw members  1104 ,  1106  may prove advantageous in effecting parallel closure of the jaw members  1104 ,  1106 , which dramatically reduces the force required to crimp a surgical clip. As used herein, the phrase “parallel closure” refers to the relative parallel disposition of the opposing inner surfaces of the jaw members  1104 ,  1106  throughout their entire range of motion as the jaw members  1104 ,  1106  move between open and closed positions. Parallel closure is often used with respect to medical device end effectors and is desirable to minimize tissue damage due to non-uniform pressure or milking (squeezing out) of tissue from between opposed jaw members. 
     Conventional clip appliers typically include a cam that moves distally to slidingly engage opposed and connected jaw members. As the cam advances over the jaw members, the jaw members act as individual cantilever beams as they are urged toward one another by the cam. Because the jaw members act as cantilever beams, the distal ends or “tips” of the jaw members come together first, at which point each jaw member is effectively converted into a fixed-pinned beam, which increases the stiffness of the system. As opposed fixed-pinned beams, the lateral force required to fully close the jaw members along the length of the grooves defined on each jaw member increases dramatically. Consequently, this requires more expensive and powerful actuators to move (actuate) the cam and necessitates more robust materials used to make the jaws, the cam, and other intervening structural elements that facilitate jaw actuation. 
     According to embodiments of the present disclosure, the independent or separate plate-like jaw members  1104 ,  1106  eliminate distal tip-to-tip closure. Rather, the jaw members  1104 ,  1106  may be designed to achieve parallel (or substantially parallel) closure. As used herein, the term “substantially parallel” can refer to true relative parallelism between opposing members or near true relative parallelism, without departing from the scope of the disclosure. Eliminating tip-to-tip closure eliminates the need to deflect the jaw members  1104 ,  1106  between supported ends, which may prove advantageous in eliminating the additional reaction load from the opposing jaw member and minimizing jaw length. 
     Parallel closure dramatically reduces the force required to collapse the jaw members  1104 ,  1106  and helps facilitate uniform crimping of the surgical clip  1118 . This advantageously allows smaller actuators to be used to collapse the jaw members  1104 ,  1106 . Moreover, this allows the jaw members  1104 ,  1106  to be made of less-expensive materials and manufactured through less-expensive manufacturing processes. In some embodiments, for example, the jaw members  1104 ,  1106  may be made of an injection molded plastic. In other embodiments, the jaw members  1104 ,  1106  may be made of a metal and molded through a metal injection molding process. In yet other embodiments, the jaw members  1104 ,  1106  may be made of a plastic or a metal and manufactured via an additive manufacturing process (e.g.,  3 D printing). In even further embodiments, the jaw members  1104 ,  1106  may be made of a metallic base with plastic overmolding, without departing from the scope of the disclosure. 
       FIG. 14  is an isometric view of another example embodiment of the end effector  1102 . In some embodiments, as briefly mentioned above, the range of potential angular movement of the head  1112  about the pivot axis P 1  of the axle  1114  may be about 180°. In the illustrated embodiment, however, the range of potential angular movement of the head  1112  is depicted as being potentially 360° in either angular direction. This may prove advantageous in allowing the jaw members  1104 ,  1106  to be articulated to a wide range of angular clamping positions for clamping and deploying a surgical clip. 
     Embodiments disclosed herein include: 
     A. An end effector for a surgical clip applier includes a body having a proximal end and a distal end, a head arranged at the distal end, first and second jaw members mounted to the head, and a linear actuator arranged within the head and operable to collapse and open the first and second jaw members. 
     B. An end effector for a surgical clip applier includes a body having a proximal end and a distal end, a clip cartridge coupled to the body and containing one or more surgical clips, each surgical clip having a crown and a pair of legs extending from the crown, a head arranged at the distal end, and first and second jaw members mounted to the head, wherein the first and second jaw members are alignable with the clip cartridge to receive a distal-most surgical clip of the one or more surgical clips, and wherein the distal-most surgical clip is fed crown first into the first and second jaw members from the clip cartridge. 
     C. A surgical clip applier includes a drive housing, an elongate shaft that extends from the drive housing, and an end effector arranged at a distal end of the elongate shaft. The end effector includes a body having a proximal end and a distal end, a head arranged at the distal end, first and second jaw members mounted to the head, and a linear actuator arranged within the head and operable to collapse and open the first and second jaw members. The surgical clip applier further includes a drive cable extending from the drive housing to the end effector and actuatable to operate the linear actuator. 
     Each of embodiments A, B, and C may have one or more of the following additional elements in any combination: Element 1: wherein the linear actuator comprises a jaw pulley, a drive cable routed around the jaw pulley to cause rotation of the jaw pulley, a bevel gear assembly operatively coupled to the jaw pulley, and a threaded linear drive operatively coupled to the bevel gear assembly, wherein rotation of the jaw pulley causes actuation of the bevel gear assembly, which actuates the threaded linear drive and thereby operates to collapse or open the first and second jaw members. Element 2: wherein the threaded linear drive comprises a threaded gear plate providing female threading, and wherein the bevel gear assembly comprises a drive gear rotated by the jaw pulley, a driven gear intermeshed with the drive gear, and a worm gear extending from the driven gear and defining helical threading threadably matable with the female threading of the threaded gear plate. Element 3: further comprising a first angled slot defined in the first jaw member and extending at a positive angle relative to a longitudinal axis of the end effector, a second angled slot defined in the second jaw member and extending at a negative angle relative to the longitudinal axis, wherein the negative angle is of a same magnitude as the positive angle, and a transition pin that extends from a gear plate of the linear actuator and through the first and second angled slots, wherein actuation of the linear actuator moves the gear plate in a linear direction and correspondingly moves the transition pin to slidingly engage the first and second angled slots and thereby urge the first and second jaw members laterally with respect to each other. Element 4: wherein the first and second jaw members comprise independent structures laterally movable relative to one another, and wherein opposing inner surfaces defined on the first and second jaw members remain parallel to each other as the first and second jaw members laterally move relative to one another. Element 5: further comprising a clip cartridge coupled to the body and containing one or more surgical clips, each surgical clip having a crown and a pair of legs extending from the crown, wherein the one or more surgical clips are arranged within the clip cartridge with the crown leading and the pair of legs extending proximally therefrom. Element 6: wherein the first and second jaw members are alignable with the clip cartridge to receive a distal-most surgical clip of the one or more surgical clips, and wherein the distal-most surgical clip is fed crown first into the first and second jaw members from the clip cartridge. Element 7: further comprising a groove defined in an inner surface of each of the first and second jaw members, wherein the groove of each jaw member is aligned with the distal-most surgical clip. 
     Element 8: wherein the one or more surgical clips are arranged within the clip cartridge with the crown leading and the pair of legs extending proximally therefrom. Element 9: further comprising a clip pusher configured to apply an axial load on the one or more surgical clips to position the distal-most surgical clip between the first and second jaw members. Element 10: wherein the clip cartridge is removably coupled to the body. Element 11: further comprising a linear actuator operable to collapse and open the first and second jaw members, the linear actuator including a jaw pulley, a drive cable routed around the jaw pulley to cause rotation of the jaw pulley, a bevel gear assembly operatively coupled to the jaw pulley, and a threaded linear drive operatively coupled to the bevel gear assembly, wherein rotation of the jaw pulley causes actuation of the bevel gear assembly, which actuates the threaded linear drive and thereby operates to collapse or open the first and second jaw members. Element 12: wherein the first and second jaw members comprise independent structures movable laterally relative to one another, and wherein opposing inner surfaces defined on the first and second jaw members remain parallel to each other as the first and second jaw members open or close. Element 13: further comprising a first angled slot defined in the first jaw member and extending at a positive angle relative to a longitudinal axis of the end effector, a second angled slot defined in the second jaw member and extending at a negative angle relative to the longitudinal axis, wherein the negative angle is of a same magnitude as the positive angle, and a transition pin that extends from a gear plate of the linear actuator and through the first and second angled slots, wherein actuation of the linear actuator moves the gear plate in a linear direction and correspondingly moves the transition pin to slidingly engage the first and second angled slots and thereby urge the first and second jaw members laterally with respect to each other. 
     Element 14: wherein the linear actuator comprises a jaw pulley about which the drive cable is routed to cause rotation of the jaw pulley, a bevel gear assembly operatively coupled to the jaw pulley, and a threaded linear drive operatively coupled to the bevel gear assembly, wherein rotation of the jaw pulley causes actuation of the bevel gear assembly, which actuates the threaded linear drive and thereby collapses or opens the first and second jaw members. Element 15: wherein the first and second jaw members comprise independent structures laterally movable relative to one another, and wherein opposing inner surfaces defined on the first and second jaw members remain parallel to each other as the first and second jaw members laterally move relative to one another. Element 16: further comprising a clip cartridge coupled to the body and containing one or more surgical clips, each surgical clip having a crown and a pair of legs extending from the crown, wherein the one or more surgical clips are arranged within the clip cartridge with the crown leading and the pair of legs extending proximally therefrom. Element 17: wherein a distal-most surgical clip of the one or more surgical clips is fed crown first into the first and second jaw members from the clip cartridge. 
     By way of non-limiting example, exemplary combinations applicable to A, B, and C include: Element 1 with Element 2; Element 5 with Element 6; Element 5 with Element 7; Element 12 with Element 13; and Element 16 with Element 17. 
     Therefore, the disclosed systems and methods are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the teachings of the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope of the present disclosure. The systems and methods illustratively disclosed herein may suitably be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the elements that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted. 
     As used herein, the phrase “at least one of” preceding a series of items, with the terms “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list (i.e., each item). The phrase “at least one of” allows a meaning that includes at least one of any one of the items, and/or at least one of any combination of the items, and/or at least one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or at least one of each of A, B, and C.