Abstract:
The invention provides surgical or diagnostic tools and associated methods that offer improved user control for operating remotely within regions of the body, and improved methods of assembling the tools. In some embodiments these tools include a proximally-located actuator for the operation of a distal end effector, as well as proximally-located actuators for articulational and rotational movements of the end effector. Control mechanisms and methods refine operator control of end effector actuation and of these articulational and rotational movements. The articulation mechanisms comprise pairs of links, one link distal and the other proximal, configured such that movement of a proximal link is transferred to the distal link by way of tension bearing members. Embodiments of the invention include a guide for such tension bearing members that facilitates assembly of the tool. Embodiments also include improved methods for attaching tension bearing members to the links. The inventions disclosed herein may also be used with articulating devices outside of the surgical and diagnostic fields.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to the following concurrently filed US patent applications: “Tool with articulation lock” of Hegeman, Danitz, Hinman, and Alvord, “Tool with force limiter” of Hinman and Bertsch, “Tool with multi-state ratcheted end effector” of Hinman, and “Tool with rotation lock” of Hinman and Danitz. 
       INCORPORATION BY REFERENCE 
       [0002]    All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. 
       FIELD OF THE INVENTION 
       [0003]    This invention relates to articulating mechanisms and applications thereof, including the remote guidance and manipulation of surgical or diagnostic tools. 
       BACKGROUND OF THE INVENTION 
       [0004]    Surgical procedures such as endoscopy and laparoscopy typically employ instruments that are steered within or towards a target organ or tissue from a position outside the body. Examples of endoscopic procedures include sigmoidoscopy, colonoscopy, esophagogastroduodenoscopy, and bronchoscopy, as well as newer procedures in natural orifice transluminal endoscopic surgery (“NOTES”). Traditionally, the insertion tube of an endoscope is advanced by pushing it forward, and retracted by pulling it back. The tip of the tube may be directed by twisting and general up/down and left/right movements. Oftentimes, this limited range of motion makes it difficult to negotiate acute angles (e.g., in the rectosigmoid colon), creating patient discomfort and increasing the risk of trauma to surrounding tissues. 
         [0005]    Laparoscopy involves the placement of trocar ports according to anatomical landmarks. The number of ports usually varies with the intended procedure and number of instruments required to obtain satisfactory tissue mobilization and exposure of the operative field. Although there are many benefits of laparoscopic surgery, e.g., less postoperative pain, early mobilization, and decreased adhesion formation, it is often difficult to achieve optimal retraction of organs and maneuverability of conventional instruments through laparoscopic ports. In some cases, these deficiencies may lead to increased operative time or imprecise placement of components such as staples and sutures. 
         [0006]    Steerable catheters are also well known for both diagnostic and therapeutic applications. Similar to endoscopes, such catheters include tips that can be directed in generally limited ranges of motion to navigate a patient&#39;s vasculature. There have been many attempts to design endoscopes and catheters with improved steerability. For example, U.S. Pat. No. 3,557,780 to Sato; U.S. Pat. No. 5,271,381 to Ailinger et al.; U.S. Pat. No. 5,916,146 to Alotta et al.; U.S. Pat. No. 6,270,453 to Sakai, and U.S. Pat. No. 7,147,650 to Lee describe endoscopic instruments with one or more flexible portions that may be bent by actuation of a single set of wires. The wires are actuated from the proximal end of the instrument by rotating pinions (Sato), manipulating knobs (Ailinger et al.), a steerable arm (Alotta et al.), by a pulley mechanism (Sato), or by manipulation of complementary portions (Lee). U.S. Pat. No. 5,916,147 to Boury et al. discloses a steerable catheter having four wires that run within the catheter wall. Each wire terminates at a different part of the catheter. The proximal ends of the wires extend loosely from the catheter so that the physician may pull them. The physician is able to shape and thereby steer the catheter by selectively placing the wires under tension. 
         [0007]    Recently, surgical instruments, including minimally invasive surgical instruments, have been developed that are more ergonomic and which have a wider range of motion and more precise control of movement. These instruments may include mechanisms that articulate using a series of links coupled with one or more sets of tension bearing members, such as cables. As with conventional instruments used in minimally invasive surgery, rotation of the shaft and end effector with respect to the handle is also an important feature of cable and link type instruments to aid with dissecting, suturing, retracting, knot tying, etc. With increasing complexity in the cable systems comes the possibility of undesirable interaction among cables within portions of the tool. Further associated with complexity involving the cables comes an increasing level of complexity, delicacy, and tedium in the manufacture of these instruments. To address such issues, further improvements in the features and design of surgical instruments are desirable. 
       SUMMARY OF THE INVENTION 
       [0008]    The invention provides an articulating tool with an improved tension member design as well as methods of assembling such tools. The articulating tool is appropriate for multiple uses, including medical uses such as diagnostic and surgical uses. Embodiments of the articulating tool include a shaft having a proximal and a distal end, an articulation mechanism, and an elongated guide located along at least a portion of the shaft, the guide being configured to guide the tension bearing members. The articulation mechanism includes a movable proximal element disposed at the proximal end of the shaft, a movable distal element disposed at the distal end of the shaft, and a plurality of tension bearing members extending between the proximal and distal elements such that movement of the movable proximal element with respect to the shaft causes a corresponding movement of the movable distal element with respect to the shaft. 
         [0009]    Embodiments of the guide include a plurality of channels extending along its length, each channel for receiving one of the plurality of tension bearing members. In some embodiments the channels are circumferentially closed; in other embodiments the channels are grooves. Embodiments of the channels include those that form a generally straight path, and those that form a generally helical path. Embodiments that form a helical path may revolve about 180 degrees. 
         [0010]    The guide may be generally circular in cross section with the channels spaced around the circumference of the cross section. Some embodiments of the guide are configured to guide at least three tension bearing members; others are configured to guide at least six tension bearing members. The guide may further include a central channel for receiving a tension bearing member in addition to the aforementioned plurality. In some embodiments there may be two or more such central channels, the channels for receiving operable elements of the tool. Exemplary operable elements in addition to tension-bearing and compression-bearing members, may include elements such as wires, optical fibers, and hydraulic or vacuum tubes. 
         [0011]    In some embodiments of the tool, the tension bearing members are also compression bearing members. In some embodiments of the tool, the shaft includes a tube, wherein the elongated guide has a length and a constant cross section along substantially its entire length, and wherein the guide element is located within the tube. In some embodiments of the tool, the elongated guide element is made of a flexible polymer. And in some embodiments, both the shaft and the guide are flexible. 
         [0012]    Embodiments of the tool include a fixed attachment between the movable proximal element and the proximal end of tension bearing members. In some embodiments of the tool, fixed attachment comprises a crimp in the movable proximal element; in other embodiments, the fixed attachment comprises an ultrasonic weld in the movable proximal element. 
         [0013]    In some embodiments of the tool, an end cap for guiding the plurality of tension bearing members is disposed at least one end of the shaft. In some of these embodiments, the shaft itself includes the end cap. In some of these embodiments, the end cap guides each of the tension bearing members from a first radial distance to a second radial distance from a central axis. And in some of these embodiments, end cap is located adjacent to a proximal end of the shaft, and the first and second radial distances differ by a factor of about three. In some of the tool embodiments with an end cap, the end cap and the elongated guide have inter-engaging rotational alignment features. 
         [0014]    Embodiments of the invention also include a method of assembling the above summarized tool with an elongated guide. The method includes inserting the elongated guide into a lumen of the shaft element, attaching the end cap to an end of the lumen, and inserting at least one of the tension bearing members through the end cap and the guide. 
         [0015]    This method may further include rotating at least one end of the guide around a longitudinal axis relative to an opposite end of the guide, and fixing the relative positions of the rotated ends. Embodiments of this method include a step order in which the inserting step is performed before the rotating step, as well as an order in which the rotating step is performed before the inserting step. 
         [0016]    The method may further include deforming the movable proximal element so as to attach the proximal element and the proximal end of the tension bearing element together. And it may also include deforming the movable distal element so as to attach the distal element and the distal end of the tension bearing element together. 
         [0017]    Embodiments of the invention also include an articulating tool having a distal portion and a proximal portion as well as an articulation mechanism for manipulating angular orientation of the distal portion. The articulation mechanism includes a pair of links, the pair including a proximal link on the proximal portion of the tool and a distal link on the distal portion of the tool. The mechanism further includes a plurality of tension bearing members interconnecting the proximal and distal links such that movement of the proximal link causes corresponding relative movement of the distal link through the tension bearing members. In these embodiments, a portion of one of the links adjacent to a tension bearing member is deformed against the member, thereby fixedly attaching the member and the link together. 
         [0018]    In some of these embodiments, the link portion is deformed by a crimping process. In other embodiments, the link is formed of plastic and the link portion has been deformed by an ultrasonic welding process. In some embodiments, both of the proximal and distal links include a portion deformed against a tension bearing member. In other embodiments, one link of the pair of links includes a portion deformed against a tension bearing member and the other link includes a pocket for receiving an enlarged portion of the tension bearing member. In some of these embodiments, one link of the pair of links includes at least three of the deformed portions and the other link includes at least three of the pockets. In some of these embodiments, the pocket on the other link is located on a peripheral edge of that link. In other embodiments, the enlarged portion of the tension bearing member may only enter the pocket from a radial direction. 
         [0019]    Some embodiments of the tool include at least two pairs of links, and the tool may also include at least three tension bearing members interconnecting each pair of links. In some embodiments of the tool, the tension bearing members are also compression bearing members. 
         [0020]    Some embodiments of the articulating tool include an end effector disposed at a distal portion of the tool, a handle at a proximal portion of the tool, a shaft element supporting the end effector, an articulation mechanism for manipulating angular orientation of the end effector with respect to the shaft, and a guide element configured to guide the tension bearing members. The articulation mechanism of this embodiment includes a plurality of tension bearing members. 
         [0021]    Some embodiments of the articulating tool include an end effector disposed at a distal portion of the tool, a handle at a proximal portion of the tool, a shaft element supporting the end effector, an articulation mechanism for manipulating angular orientation of the end effector with respect to the shaft, and a guide element configured to guide the tension bearing members. The articulation mechanism of this embodiment includes a plurality of tension bearing members. In some of these embodiments, there is a connection between each member of the plurality of tension bearing members and a distal link, the link configured to manipulate or contribute to the manipulation of the angular orientation of the end effector. In some of these embodiments, the connection is formed by a crimp of the distal link against the member; in other embodiments the connection is formed by an ultrasonic weld of the distal link and the member. 
         [0022]    Some embodiments of the tool include a shaft with a proximal and a distal end, an articulation mechanism, and a plurality of channels extending the length of the shaft between the proximal and distal end. The articulation mechanism includes a movable proximal element at the proximal end of the shaft and a movable distal element at the distal end of the shaft, and a plurality of tension bearing members extending between the proximal and distal elements so that movement of the proximal element with respect to the shaft causes a corresponding movement of the distal element with respect to the shaft. In these embodiments, each channel of the plurality of channels is configured to guide one of the plurality of tension bearing members along the shaft. The channels are disposed at a radial distance from the central axis of the shaft, and in some of these embodiments the radial distance is variable along the length of the shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The novel features of the invention are set forth with particularity in the claims that follow. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings which are briefly described below. 
           [0024]      FIG. 1A  is an obliquely distal-looking perspective view of an exemplary articulating device having a handle and an end effector.  FIG. 1B  is a detailed view of the circled portion of  FIG. 1A , which includes proximal links and an end-cap housing cover of a tension bearing member guide. 
           [0025]      FIG. 2  shows the device of  FIG. 1  in a proximal-looking view, with the handle and end effector in an articulated position.  FIG. 2B  is a detailed view of the circled portion of  FIG. 2A , which includes distal links and distal end-cap housing cover of a tension bearing member guide. 
           [0026]      FIG. 3  is an exploded perspective view of certain proximal components of the articulating device. 
           [0027]      FIGS. 4-6  show details of an end cap for use with the articulating device. 
           [0028]      FIGS. 7-9  show details of a proximal end cap housing for use with the articulating device. 
           [0029]      FIGS. 10-12  show details of a distal end cap for use with the articulating device. 
           [0030]      FIG. 13A  is an end view of a tension bearing element guide for use with an articulating device. 
           [0031]      FIG. 13B  is an end view of an alternative embodiment tension bearing element guide. 
           [0032]      FIG. 14  is a perspective view of the tension bearing element guide of  FIG. 13 . 
           [0033]      FIG. 15  is a partial exploded view of the proximal end cap of  FIGS. 7-9  and the tension bearing element guide of  FIG. 13 . 
           [0034]      FIG. 16  is a partial exploded view of the distal end cap of  FIGS. 10-12  and the tension bearing element guide of  FIG. 13 . 
           [0035]      FIG. 17  is a perspective view showing the tension bearing element guide twisted 180°. 
           [0036]      FIG. 18  is a cross-sectional view showing proximal elements of the articulating device. 
           [0037]      FIG. 19  is a partial exploded view of the articulating device shown in  FIGS. 1-18 . 
           [0038]      FIG. 20  is a perspective view showing a distal end of an articulating tool according to one embodiment of this invention. 
           [0039]      FIGS. 21 and 22  show details of a proximal link according to one embodiment of this invention. 
           [0040]      FIGS. 23 and 24  show details of another proximal link according to one embodiment of this invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0041]    Articulating tools are described in U.S. Pat. No. 7,090,637; US 2005/0107667; US 2005/0273084; US 2005/0273085; US 2006/0111209, US 2006/0111210, and US 2006/0111615. The articulating mechanisms of the tools described in those publications use multiple pairs of segments or links controlled, e.g., by multiple sets of cables, as well as tools that have a single pair of links, connected by a single set of cables, such as those described in U.S. Pat. No. 5,916,146. Depending upon the specific design of the device, the links can be discrete segments (as described, e.g., in U.S. Pat. No. 7,090,637) or discrete portions of a flexible segment (as described, e.g., in US 2005/0273085). The instrument may also include steerable or controllable links, e.g., as described in US 2005/0273084, US 2006/0111209 and US 2006/0111210. Embodiments of the invention are not specific to any particular type of link, and may include any type of link known in the art. The devices of this invention may include optional end effectors at their distal ends and end effector actuators supported by a handle at their proximal ends. When using such articulating instruments, a user may manipulate the proximal end of the instrument, thereby moving one or more distal links of the articulation mechanism. 
         [0042]      FIGS. 1A and 2A  show an articulatable tool  100  with an end effector  102  at its distal end and an end effector actuator  104  within a handle  106  at its proximal end:  FIG. 1A  shows the tool in a neutral or non-articulated configuration, while  FIG. 2A  shows the tool in an articulated position or configuration.  FIG. 1B  shows detail (encircled in  FIG. 1A ) of the proximal links of the tool and the proximal end-cap cover of a tension bearing member guide system.  FIG. 2B  shows detail (encircled in  FIG. 2A ) of the distal links of the tool and the distal end-cap cover of a tension bearing member guide system. Instrument  100  may be used, e.g., in a laparoscopic procedure requiring grasping or cutting within a patient. Exemplary embodiments of the tool  100  may also be useful in endoscopic procedures, particularly when, as in some embodiments, the tool has a flexible shaft. Still other embodiments may be used for percutaneous procedures, such as a catheter. Still other embodiments include devices that are directed toward natural orifice transluminal endoscopic surgery (“NOTES”). Embodiments of the invention may include a wide variety of tools, some with medical or diagnostic purposes, and others that are applied to other types of tasks where the articulational capabilities of the tool provide benefit. 
         [0043]    Proximal articulation links  108  and  110  extend distally from handle  106 , and distal articulation links  112  and  114  extend proximally from end effector  102 . Proximal link  108  is a spindle and is connected to and moves with handle  106 . Likewise, distal link  112  is connected to and moves with end effector  102 . An elongated shaft  116  is disposed between the proximal links and the distal links; in some embodiments the shaft is rigid, in other embodiments the shaft may be flexible. 
         [0044]    A set of tension bearing elements or control cables  118  is attached to proximal link  108 , extends through proximal link  110 , shaft  116  and distal link  114  and is attached to distal link  112 , as shown in  FIGS. 1A and 1B . A second set of tension bearing element or control cables  120  is attached to proximal link  110 , extends through shaft  116  and is attached to distal link  114 . In this embodiment, there are three control cables  118  in the first set and three control cables  120  in the second set. It should be appreciated, however, that other numbers of control cables may be used to connect corresponding proximal and distal links. In addition, tension bearing elements other than cables may be used to connect corresponding links. 
         [0045]    As shown in  FIGS. 1A ,  1 B,  2 A, and  2 B, movement of handle  106  and proximal link  108  with respect to proximal link  110  moves end effector  102  and distal link  112  in a relative and corresponding manner. Likewise, movement of proximal link  110  with respect to shaft  116  moves distal link  114  with respect to shaft  116  in a relative and corresponding manner, also as shown in  FIG. 2 . This relative articulation movement provides a way for a user to remotely manipulate the end effector through movement of the handle. It should be understood that the proximal and distal links can be connected by the tension bearing elements so as to move in the same direction with respect to the shaft (thereby providing a mirror image movement) or in opposite directions with respect to the shaft, depending on whether the tension bearing elements connect the corresponding links on the opposite sides or on the same sides of the links, respectively. In addition, the degree of relative movement can be determined by the relative diameters of the cables&#39; connections to corresponding links as well as through the use and specific design of bushings or spacer links separating the connected proximal and distal links. For example, in the embodiment shown in  FIGS. 1-20 , the cables&#39; radial spacing on the proximal links is about three times greater than their radial spacing on the distal links. This means that a movement of about 5° in a proximal link will cause a corresponding movement of about 15° in a distal link. Further details of these links are provided in US2005/0273085, which is hereby incorporated by this reference. 
         [0046]    In the embodiment illustrated in  FIG. 1 , the end effector  102  is a pair of jaws. Actuation force is transmitted from end effector actuator  104  through a transmission that includes a linearly movable rod and a rotatable rod actuator (not shown). Other end effectors (surgical, diagnostic, etc.) and end effector actuators may be used with the articulating tool of this invention. In some embodiments, the distal links, themselves, can comprise an end effector, such as, for example, a retractor. The movable rod may comprise any flexible material; in some embodiments Nitinol offers particular advantages as it is sufficiently flexible to accommodate articulation, and yet can still carry a compressive load sufficiently, for example, to be able to push open an end effector, such as a set of jaws. In some embodiments, a series of proximal links, themselves, can comprise a “handle” with no other rigid handle being provided. In other words, the proximal links may be formed into a particular shape which is emulated by a corresponding series of distal links. More details of such embodiments are provided in U.S. Pat. No. 7,090,637. 
         [0047]      FIG. 3  shows an exploded view of certain proximal components of the articulating tool. The tension bearing elements have been omitted for clarity. As shown, a double headed bushing  109  is disposed between links  108  and  110 , and another bushing  111  is disposed between links  110  and a proximal end cap  300 . The interaction of bushings  109  and  111  with links  108  and  110  and with proximal end cap  300  is described in more detail in U.S. 2005/0273084, U.S. 2006/0111209, and U.S. 2006/0111210. If the tension bearing cables  118  and  120  were shown in  FIG. 3  as they are in  FIGS. 1 and 2 , the proximal ends of the three cables  118  would terminate in openings  1806  of link  108 , and the cables would pass through openings  1820  in link  110  and openings  304  in end cap  300  before entering shaft  116 . Likewise, the proximal ends of three cables  120  would terminate in openings  1822  of link  110  and would pass through openings  304  in proximal end cap  300  before entering shaft  116 . A tapered end cap housing or cover  306  is rigidly fixed to shaft  116  and provides a transition from end cap  300  to shaft  116 . 
         [0048]      FIGS. 4-6  show details of end cap  300 . Cable openings  304  lead to channels  308  extending distally from the end cap proximal face. Channels  308  taper the radial distance between the cables within the proximal links  108  and  110  to a radial distribution suitable for the diameter of shaft  116 . Channels  308  depicted are in the form of grooves. In other embodiments (not shown) channels may be in a circumferentially enclosed form. An opening  310  is provided for passage of the end effector actuation rod. A pair of pins  312  connect the end cap  300  to the end cap housing, as explained below. A pair of tines  314  connect with a shaft cable guide, as is also explained below. 
         [0049]      FIGS. 7-9  show details of the end cap housing  306 . A pair of holes  320  mate with the pins  312  of end cap  300 . Channels  322  may be formed on the inner surface of housing  306 . These channels  322  line up with channels  308  of end cap  300  to help guide the cables as they transition from the proximal links into the shaft. A stepped distal opening  307  surrounds the proximal end of the shaft  116  (as shown in  FIG. 18 ). The proximal end cap  300  and end cap housing  306  cooperate to provide a smooth transition between the cables&#39; radial distribution within the shaft and their radial distribution on the proximal links. As shown in  FIG. 18 , cables  118  and  120  are constrained by the cooperating channels of end cap  300  and end cap housing  306  to limit any lateral movement of the cables. 
         [0050]      FIGS. 10-12  show details of a distal end cap  400 . Like the proximal end cap, distal end cap  400  cooperates with a link bushing in the articulation mechanism and therefore has a socket  402  on its distal face and other features to interface with a bushing. Openings  404  line up with channels  406  to guide the tension bearing cables to the distal links. A pair of tines  408  connect with the shaft cable guide, and a tab  409  indexes end cap  400  with the shaft. An opening  410  permits passage of the end effector actuation rod. 
         [0051]    Some embodiments of the invention have a tension bearing element guide extending along part or all of the shaft. One purpose of this guide is to maintain the relative position and orientation of the cables or other tension bearing members within the shaft. The guide also aids in the initial assembly of the tool, as discussed below. 
         [0052]      FIGS. 13-19  show one embodiment of a shaft cable guide  420  and its interaction with proximal end cap  300  and distal end cap  400 . Guide  420  has channels  422  in which the cables  118  and  120  or other tension bearing elements or elements may be disposed. Channels  422  depicted are in the form of grooves. In other embodiments ( FIG. 13B ) channels may be in a circumferentially enclosed form. In this embodiment, the proximal ends of channels  422  line up with channels  308  in proximal end cap  300  (as shown in  FIG. 15 ) and the distal ends of channels  422  line up with channels  406  in distal end cap  400  (as shown in  FIG. 16 ). To help with alignment, tines  314  of proximal end cap  300  can mate with the proximal ends of alignment channels  424  in guide  420  (as shown in  FIG. 15 ), and tines  408  of distal end cap  400  can mate with the distal ends of alignment channels  424  (as shown in  FIG. 16 ). 
         [0053]    Some embodiments may include a central channel or lumen  426  in guide  420  ( FIG. 13A ) that permits passage of an operable element such as the articulating tool&#39;s movable actuation rod  125  (as shown in  FIG. 18 ), which further functions to prevent buckling of the actuation rod during its movement. The rod  125 , in some embodiments, in addition to being a tension bearing member may further be a compression bearing member. Central channel or lumen  426  should be understood as being generally centrally-located, the channel need not be dead centrally located, and may be off-center. In some embodiments the guide may include one or more additional channels or lumina  426 ′ and  427 , as seen in  FIG. 13B , with four exemplary channels. These channels  426 ′ and  427  are generally centrally-disposed, in contrast to the more circumferentially disposed channels  422  or  422 ′. Such separate channels  426 ′ and  427 , in addition to accommodating movable actuation rod  125 , may further accommodate other operable elements or components such as any type of tension bearing member or compression bearing member, wires, cables, hydraulic lines, vacuum lines, optical fibers, or any element useful in the operation of the distal portion of the tool. Separation of the central lumen into separate lumina provides for segregation of components or elements contained therein, and may facilitate the assembly of the tool, or the independence of the operation of the elements contained therein. As seen in  FIG. 13B , tension member channels  422 ′ and alignment channel  424 ′ may have a closed configuration. Guide  420 ′ of  FIG. 13B  may be used within a shaft tube as described below. Alternatively, in some embodiments, guide  420 ′ may itself serve as a shaft. 
         [0054]    In the orientation shown in  FIG. 14 , tension member guide  420  guides the cables or other tension bearing members axially along the shaft so that the cables&#39; entry and exit points are at the same circumferential positions about the circumference of the shaft to provide movement of distal links that is opposite to the movement of their corresponding proximal links. For example, in this orientation of the guide  420 , movement of a proximal link to the right of the shaft will cause movement of the corresponding distal link to the left of the shaft. To provide mirrored movement of proximal and distal links, the cables or other tension bearing elements must connect to the distal links at positions 180° opposite to their circumferential connection position on the corresponding proximal links. To accomplish this shift in circumferential position without entanglement of the cables, guide  420  may be twisted 180° from proximal to distal end, as shown in  FIG. 17 . It should be understood that guide  420  may also be twisted more or less than 180°, as desired. 
         [0055]    In one embodiment, guide  420  may be made of plastic through an extrusion process. The guide can be formed with any desired amount axial twist, a twist of about 180° being typical, or the twist can be added during the assembly process, as described below. Further, other types of manufacturing processes known in the art may be used to form the guide, and in some embodiments it may be desirable to assemble multiple components into a whole to form the guide. 
         [0056]    A variety of protocols and procedural steps may be used to assemble an articulating tool with embodiments of the tension member guide. The following procedure is provided merely by way of example. When assembling the articulating tool of the embodiment shown, the proximal end cap housing  306  may be rigidly attached to shaft  116 . The proximal end cap  300  may also be rigidly attached to the proximal end of guide  420  by pressing tines  314  into the corresponding channels  424  in the guide and then gluing, if necessary. The proximal end cap/guide subassembly may then be inserted into the proximal end of end cap housing  306 , as suggested by  FIG. 19 , by inserting pins  312  into holes  320  in the end cap housing. The tines  408  of distal end cap  400  may then be inserted into the distal ends of guide channels  424 . Distal end cap  400  and the distal end of guide  424  may then be twisted 180° (or any other angle), if desired, before attaching by inserting tabs  409  into corresponding slots in the distal end of shaft  116 . As mentioned above, other variations on assembly can by recognized by those practiced in manufacturing arts. Briefly, for example, the guide  420  could be fixed to proximal end cap  300 , or guide  420  could be fixed to distal end cap  440 , or guide  420  could be inserted into the shaft  116  and then end caps fixed thereto, or tension members or cables could be first inserted into the guide, and the guide thence into the shaft. After assembly of the shaft, end cap housing, end caps, and tension bearing element guide, the cables and links may be assembled. 
         [0057]    As would be clear to those practiced in manufacturing arts, the threading of cables may be performed by threading either the proximal ends or the distal ends forward in their respective appropriate direction. Further, any number of cable sets may be threaded during a threading procedure, in any order. The following detailed procedure is provided merely by way of an example wherein a single cable set is threaded in a particular direction. In the embodiment shown in  FIGS. 1-20 , three cables  118  extend from distal link  112  to proximal link  108 , and three cables  120  extend from distal link  114  to proximal link  110 . Proximal ends of cables  120  may be passed through openings  440  distributed about the circumference of distal link  114  such that they emerge from the openings on the proximal face of distal link  114 , as best seen in  FIG. 20 . Proximal ends of cables  120  may then be passed through openings  404  and channels  406  in distal end cap  400 , and into channels  422  in guide  420 . Channels  422  guide the proximal ends of cables  120  to channels  308  and openings  304  in proximal end cap  300 , either with or without a twist, depending on the orientation of guide  420 . The proximal ends of cables  120  then exit the proximal end cap  300  in the proper orientation for attachment of cables  120  and proximal link  110  to each other. Such attachment or anchoring may be accomplished by one or more of a variety of attachment methods, such as by crimping, ultrasonic welding, gluing, or by applying set screws. Some examples of these attachment methods are further described below. While  FIG. 20  shows an end effector  102  with jaws, it should be understood that other kinds of end effectors or no end effector may be used with the articulating tool of this invention. 
         [0058]    By use of an embodiment of the tension member guide  420  through any of the methods as described above, or an equivalent method, it can be understood that the threading of cables from one end (proximal or distal) of the guide to the other end (or if already assembled within a shaft, from one end of to a shaft assembly to the other end) becomes quite simple and fool proof. Inserting one of a member into an end cap opening and thence into a guide channel assures the direction of that member end to the appropriate opening on at the opposite end cap opening. Thus, a benefit of the inventive guide and associated methods relates to the creation of a significant saving of time required for assembly of the tool. 
         [0059]    In one exemplary embodiment of cable and link attachment, the distal ends of cables  120  have enlarged portions that may be received within openings  440  as shown in  FIG. 20  to prevent the distal ends from being pulled proximally through distal link  114 . Likewise, the proximal ends of cables  118  are passed through openings  442  distributed about distal link  112 , through distal link  114 , distal end cap  400 , down guide  420  through shaft  116 , through proximal end cap  300  and proximal link  110 , and are attached to proximal link  108 . Guide  420  once again provides the proper position and orientation for cables  118 . 
         [0060]      FIGS. 21 and 22  show details of one embodiment of a tension member attachment method.  FIGS. 21 and 22  are distal-looking perspective views of proximal link  110  before and after, respectively, being deformed by a crimping process. Holes  1820  are provided through proximal link  110  for receiving cables  118  and holes  1822  are provided for receiving cables  120  (cables  118  and  120  can be seen in  FIGS. 1 ,  2 ,  18  and  20 ). In the embodiment shown, cables  118  slidably pass through holes  1820  in proximal link  110  to terminate at proximal link  108  (as discussed below), and cables  120  terminate in holes  1822  of proximal link  110 . To anchor cables  1822  to proximal link  110 , a portion  1824  of circumferential surface  1826  may be inwardly deformed to collapse each hole  1822  ( FIG. 22 ) onto a cable  120 . Hole  1828  through the center of proximal link  110  (see  FIG. 18 ) may be provided with an appropriately small or fitted diameter to constrain rod  125  from undesirable lateral movement, flexion, or buckling as it passes through link  110 . 
         [0061]      FIGS. 23 and 24  show further details a crimp as applied to proximal link  108  which is integrated with a spindle element  117 . (Further details of spindle  117  may be found in co-pending US patent application titled “Articulating Tools with Rotation Lock,” filed concurrently with this application.). Through holes  1806  may be provided in link  108  for receiving the proximal ends of cables  118  (shown in  FIGS. 1 ,  2 ,  18  and  20 ) that interconnect proximal link  108  with distal link  112 . In the embodiment shown in the figures, only three of the six holes of proximal link  108  are used (i.e. holes  1806  are used but holes  1807  are not). Alternatively, the proximal ends of cables  120  may pass freely through the three vacant holes  1807  of proximal link  108  after being attached to proximal link  110  as described above so that all six cables can be cut at the same location proximal to link  108 . The proximal ends of cables  118  may be secured within holes  1806  of link  108  by a crimping process, such as described above in relation to  FIGS. 21 and 22 . Alternatively, a smaller crimping die may be pressed radially inward from the circumferential surface  1808  of link  108  to deform the material adjacent to the cable end, leaving an indentation  1810  and securing the cable end from axial movement relative to link  108 . 
         [0062]    Other means may be used to secure proximal and/or distal ends of cables  118  and  120  to links  108 ,  110 ,  112 , or  114 , such as soldering, ultrasonic welding, clamping, use of set screws, glue or other adhesives. Links  108 ,  110 ,  112 , or  114  may be made from a variety of materials suitable for the particular attachment process used, such as metals, plastics or ceramics. Further, the side pockets for accommodating terminating cables, for example opening  440  as shown  FIG. 2B  in the context of distal link  114 , may also be applied to cables that terminate proximal links. 
         [0063]    While the inventive surgical instruments and devices with an improved tension member guide have been described in some detail by way of illustration, such illustration is for purposes of clarity of understanding only. It will be readily apparent to those of ordinary skill and in the art in light of the teachings herein that certain changes and modifications may be made thereto without departing from the spirit and scope of the appended claims. For example, while the tool embodiments described in here have typically been in the context of tools with an articulating mechanism comprising at least two links, the tension member guide system may be used in an instrument comprising only a single link, a multiplicity of links, and with any number of tension members such as cables, or numbers of cable sets operably connecting the links. Further, the tension member guide system may be used in tools that are absent various features that may be associated with some articulatable instruments, such as handles, rotatability features, and dedicated end effectors. Finally, while the context of the invention is considered to be surgical or medical diagnostic procedures, the tension member guide system or tool having such a system may have utility in other non-medical contexts as well.