Abstract:
A surgical instrument including a manipulator, a proximal joint mounted to the manipulator, a hollow elongated member mounted to the proximal joint, a distal joint mounted to the hollow elongated member, and an end effector mounted to the distal joint. The proximal joint and the distal joint may each include a base at each end with a central feature disposed between the bases. The central features may provide for articulation about two perpendicular axes, may be substantially ball-shaped, and may define guides in their surfaces to receive cables, and perpendicular slots may be provided to receive projections from the bases. Cables engage the central features to operatively couple the manipulator, proximal joint, and distal joint, and may concurrently operatively couple the manipulator and the end effector.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority of U.S. Provisional Application No. 61/642,782, filed May 4, 2012, entitled “Surgical Tool,” the contents of which are hereby incorporated by reference in their entirety. 
     
    
     BACKGROUND 
       [0002]    Embodiments described herein generally relate to surgical apparatus for tissue and suture manipulation, and more particularly to apparatus that may be applied to conducting laparoscopic and endoscopic surgery. 
         [0003]    Minimally invasive (endoscopic) surgery encompasses a set of techniques and tools, which are becoming more and more commonplace in the modern operating room. Minimally invasive surgery causes less trauma to the patient when compared to the equivalent invasive procedure. Hospitalization time, scarring, and pain are also decreased, while recovery rate is increased. 
         [0004]    Endoscopic surgery is accomplished by the insertion of a trocar containing a cannula to allow passage of endoscopic tools. Optics for imaging the interior of the patient, as well as fiber optics for illumination and an array of grasping and cutting devices are inserted through a multiple cannulae, each with its own port. 
         [0005]    Currently the majority of cutting and grasping tools are essentially the same in their basic structure. Standard devices consist of a user interface at the proximal end and an end effector at the distal end of the tool used to manipulate tissue and sutures. Connecting these two ends is a tube section, containing cables or rods used for transmitting motion from the user interface at the proximal end of the tool to the end effector at the distal end of the tool. The standard minimally invasive devices (MIDs) provide limited freedom of movement to the surgeon. The cannula has some flexibility of movement at the tissue wall, and the tool can rotate within the cannula, but such tools cannot articulate within the patient&#39;s body, limiting their ability to reach around or behind organs or other large objects. Several manually operated devices have attempted to solve this problem with articulated surgical tools that are controlled much in the same way as standard MIDs. These devices have convoluted interfaces, making them more difficult to control than their robotic counterparts. Many lack torsional rigidity, limiting their ability to manipulate sutures and denser tissue. 
         [0006]    Robotic surgical instruments have attempted to solve the problems that arise from the limitations of standard MIDs with telemetrically controlled articulated surgical tools. However, these tools are often prohibitively expensive to purchase and operate. The complexity of the devices raises the cost of purchasing as well as the cost of a service contract. These robotic solutions may also have several other disadvantages such as complications during the suturing process and in some cases a lack of haptic feedback. 
         [0007]    In the case of both articulated hand-held devices and robotic devices, the issue of compactness and strength are high priorities in terms of design. Many previously proposed articulated devices require a significant amount of space to articulate properly. 
       SUMMARY 
       [0008]    Embodiments of a surgical instrument are disclosed for use in a wide variety of roles including grasping, dissecting, clamping, or retracting materials or tissue during surgical procedures performed within a patient&#39;s body and particularly within the abdominal cavity. 
         [0009]    The surgical instrument disclosed herein may comprise a manipulator adapted to receive at least a portion of the operator&#39;s hand, a proximal joint having a first base and a second base and including a first central feature that provides for articulation about two perpendicular axes, the proximal joint first base being mounted to the manipulator, a hollow elongated member having a first end, a second end, and a longitudinal axis, the elongated member first end being mounted to the proximal universal joint second base, a distal joint having a first base and a second base and including a second central feature that provides for articulation about two perpendicular axes, the distal joint first base being mounted to the elongated member second end, an end effector including at least one movable jaw, the end effector mounted to the distal joint second base, and cables that engage the first central feature and the second central feature to operatively couple the manipulator, proximal joint, and distal joint. 
         [0010]    The distal joint in one embodiment is controlled by four cables, which in turn also control the jaws. There are three primary motions that these cables actuate: rotation about a primary joint axis, rotation about a secondary joint axis, and the opening and closing of the jaws. The embodiment described below is such that the end effector may be controlled by a manual interface or a robotic interface. 
         [0011]    The instrument described below is one embodiment that can control the joint and jaws manually. The four cables that control the distal joint and jaws pass through the endoscopic tube section to the proximal joint. In one aspect, the cables terminate in the manipulator and the end effector. The cables follow guides in a path partially around each of a first central feature and a second central feature. 
         [0012]    A second embodiment is also described in which four cables control the proximal and distal joints and a fifth cable passes through the center of these joints to control the jaws. The joint control cables terminate in the proximal and distal joints, while the jaw control cable passes through these joints and terminates in the jaw control pin at the distal end and the trigger at the proximal end. Additionally, in either of these embodiments the four joint control cables may be designed as a composite actuation system wherein the jaw assembly and distal joint contain cables that connect to rods in the tube portion which in turn connect to cables that continue into the proximal joint and interface assembly. The added rigidity of the rod portion of this actuation system may reduce backlash in the instrument as a whole. 
         [0013]    The jaws may be of any of a variety of configurations. They may be tailored to a specific task, such as suture grasping, tissue grasping, tissue dissection or electrocautery. The embodiment described below is such that all of these specific tasks can be easily adapted to the current description. 
         [0014]    Further, in one aspect an endoscopic surgical grasper is provided with a joint such that the grasper can articulate with two degrees of freedom. 
         [0015]    In another aspect, the surgical grasper may be controlled robotically. 
         [0016]    In another aspect, the surgical grasper may be controlled by a manual interface. 
         [0017]    In another aspect, an endoscopic surgical end effector is provided that is adaptable to multiple different jaw structures for different surgical procedures. 
         [0018]    In another aspect, an endoscopic surgical instrument is provided that utilizes a proximal joint and interface to control a distal joint and jaws for performing a variety of surgical tasks. 
         [0019]    In another aspect, a hybrid actuation system is provided that utilizes a combination of rods and cables to provide articulation control with reduced backlash as compared with cables alone. 
         [0020]    Further features of the subject invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Preferred embodiments of the subject invention will be described hereinbelow with reference to the drawings, wherein: 
           [0022]      FIG. 1  is a right side perspective view of an embodiment of a surgical instrument. 
           [0023]      FIG. 2  is a right side exploded perspective view of the surgical instrument as shown in  FIG. 1 . 
           [0024]      FIG. 3  is a right side perspective view of the surgical instrument as shown in  FIG. 1  in an articulated position. 
           [0025]      FIG. 4  is a right side elevation view of the surgical instrument as shown in  FIG. 1  in an articulated position about its primary axes. 
           [0026]      FIG. 5  is a top plan view of the surgical instrument as shown in  FIG. 1  in an articulated position about its secondary axes. 
           [0027]      FIG. 6  is a right side perspective view of a distal end of the surgical instrument as shown in  FIG. 1 . 
           [0028]      FIG. 7  is a right perspective view of a distal end of the surgical instrument as shown in  FIG. 6  showing the cabling system. 
           [0029]      FIG. 8  is a right side exploded perspective view of a distal end of the surgical instrument as shown in  FIG. 7 . 
           [0030]      FIG. 9  is a right side perspective view of a distal joint for use in the surgical instrument as shown in  FIG. 1 . 
           [0031]      FIG. 10  is a right side exploded perspective view of the distal joint as shown in  FIG. 9 . 
           [0032]      FIG. 11  is a top exploded perspective cross-section view of the joint as shown in  FIG. 10 . 
           [0033]      FIG. 12  is a right side exploded perspective cross-section view of the joint as shown in  FIG. 10 . 
           [0034]      FIGS. 13-16  are views of a ball for use in a joint as shown in  FIG. 9 . 
           [0035]      FIG. 17  is a right side perspective exploded perspective view of the joints of the cabling system as shown in  FIG. 7 . 
           [0036]      FIG. 18  is right side elevation view of a proximal end of the surgical instrument as shown in  FIG. 1 . 
           [0037]      FIG. 19  is a right side exploded elevation view of an interface assembly of the proximal end of the surgical instrument as shown in  FIG. 1 . 
           [0038]      FIG. 20  is a right side perspective view of the cabling system as shown in  FIG. 7  in an articulated position about its primary axes. 
           [0039]      FIG. 21  is a right side perspective view of the cabling system as shown in  FIG. 7  in an articulated position about its secondary axes. 
           [0040]      FIG. 22  is a right side perspective view of the cabling system as shown in  FIG. 7  with the jaws in an open position. 
           [0041]      FIG. 23  is a right side section view of the interface assembly of the surgical instrument as shown in  FIG. 1  with the trigger in an open position. 
           [0042]      FIG. 24  is a right side section view of the interface assembly of the surgical instrument as shown in  FIG. 1  with the trigger in a closed position. 
           [0043]      FIG. 25  is a right side perspective view of an alternate embodiment of a distal joint for use in the surgical instrument as shown in  FIG. 1 . 
           [0044]      FIG. 26  is a right side exploded perspective view of the joint as shown in  FIG. 25 . 
           [0045]      FIG. 27  is an exploded top section view of the joint as shown in  FIG. 25 . 
           [0046]      FIG. 28  is an exploded right section view of the joint in  FIG. 25 . 
           [0047]      FIG. 29  is a right perspective view of an alternate embodiment of a cabling system and jaw assembly for use in a surgical instrument as shown in  FIG. 1 . 
           [0048]      FIG. 30  is an exploded perspective view of the cabling system and the jaw assembly as shown in  FIG. 29 . 
           [0049]      FIG. 31  is a right side perspective view of the cabling system and jaw assembly as shown in  FIG. 31  with the jaws in an open position. 
           [0050]      FIG. 32  is a right side section view of an alternate embodiment of the interface assembly for use in the surgical instrument as shown in  FIG. 1  that corresponds to the embodiment of the cabling system and jaw assembly as shown in  FIG. 29 . 
           [0051]      FIG. 33  is a right side perspective view of the distal portion an alternate embodiment of the surgical instrument as shown in  FIG. 1  with the tube removed. 
           [0052]      FIG. 34  is a right side perspective view of the proximal portion of the embodiment of the surgical instrument as shown in  FIG. 33 . 
       
    
    
     DESCRIPTION 
       [0053]    Embodiments of a surgical instrument are disclosed for use in a wide variety of roles including, for example, grasping, dissecting, clamping, electrocauterizing, or retracting materials or tissue during surgical procedures performed within a patient&#39;s body. 
         [0054]    Certain terminology is used herein for convenience only and is not to be taken as a limitation. For example, words such as “upper,” “lower,” “left,” “right,” “horizontal,” “vertical,” “upward,” and “downward” merely describe relative positions or the configuration shown in the Figures. The components may be oriented in any direction and the terminology, therefore, should be understood as encompassing such variations unless specified otherwise. 
         [0055]    Referring now to the drawings, wherein like reference numerals designate corresponding or similar elements throughout the several views, an embodiment of a surgical instrument or tool is shown in  FIGS. 1 and 2  and is generally designated at  100 . The surgical instrument  100  comprises an operator interface, or manipulator,  102  designated to be at a proximal end of the tool  100 , a proximal joint  104  mounted to the manipulator  102 , an elongated, hollow member or tube  106  one end of which is mounted to the proximal joint  104 , a distal joint  108  mounted to the other end of the tube  106 , and an end effector  110  mounted to the distal joint  108  and designated to be at a distal end of the tool  100 . The components of the embodiments of the surgical tool  100  described herein are largely symmetric about a vertical plane. A front of the device is designated as a front of the end effector  110  and other directions, which are intended as a means for comprehension of the design and not to constrain the design, are derived from this designation. The majority of views are given from a right perspective, as many of the components and assemblies are symmetrical. Features of asymmetric components are clarified with further views. 
         [0056]    The components of the surgical instrument  100  may be formed from a rigid, durable material such as, for example, stainless steel, rigid plastic and the like. It is understood that the scope of the embodiments of the surgical instrument  100  is not intended to be limited by the materials listed here, but may be carried out using any material which allows the construction and operation of the surgical instrument  100  described herein. 
         [0057]    The manipulator  102  and the end effector  110  are operatively connected with control cables contained within the tube  106 , as described herein below. The control cables may be stainless steel rope, aramid fiber cables, aligned polymer fiber cables, or the like. The manipulator  102  is gripped by in a hand of a user, such as a surgeon. When the surgeon actuates the manipulator  102 , the end effector  110  has corresponding movements. The surgical instrument  100  is shown in use in  FIG. 1  with a portion of the tube  106 , the distal joint  108 , and the end effector  110  having passed through a tissue wall  112  via a cannula  114 . The surgical instrument  100  is in a neutral position, not articulated, with the manipulator  102  and the end effector  110  in a closed position. 
         [0058]    The cabling arrangement enables the surgeon to angle the manipulator  102  with his or her hand relative to the proximal joint  104  to cause the distal joint  108  to move in a similar manner in the opposite direction, imitating the surgeon&#39;s movements and providing directional control of the distal portion of the surgical instrument  100 . Such corresponding pivoted positions of the manipulator  102  and the end effector  110  relative to the longitudinal axis of the tube  106  are shown in  FIGS. 3-5 , which show the manner in which the surgical instrument  100  articulates when the interface assembly  102  is moved by the user to an angle relative to the tube  106 . The end effector  110  is moved in the opposite direction to the same angle relative to the tube  106 . Thus, consistent alignment is maintained between the interface assembly  102  and the end effector  110 . The maximum angle of deflection θ in every direction from the longitudinal axis of the tube  106 , such as between top and bottom as shown in  FIG. 4  and side-to-side in  FIG. 5 , shows the range of motion at each end of the surgical instrument  100 . The range of motion is determined by the design of the proximal joint  104  and the distal joint  108  and the direction of deflection, and may vary from the approximately 45 degrees that is shown in the FIGs. 
         [0059]      FIGS. 6-8  show the distal end of the surgical instrument  100 . In  FIGS. 7 and 8 , the tube  106  is removed to expose the arrangement of the proximal joint  104 , the distal joint  108 , the end effector  110  and four control cables  120   w,    120   x,    120   y,    120   z.  As shown in  FIGS. 6-8 , the end effector  110  comprises a first jaw element  122 , a second jaw element  124 , a jaw base  126 , a first constraining link  136  and a second constraining link  138 . The first and second jaw elements  122 ,  124  are pivotally connected to the jaw base  126  by a primary jaw pin  128  in holes  123 ,  125  in the proximal ends of the first and second jaw elements and holes  129  in the distal ends of opposed, distally extending ears  127  of the jaw base  126 . 
         [0060]    The four control cables  120   w,    120   x,    120   y,    120   z  connect to protruding round features  134 ,  135  on the inside of the first and second jaw elements  122 ,  124 . Only the round feature  135  associated with the second jaw element  124  is visible in  FIG. 8 . Since the end effector  110  is rotationally symmetric about its longitudinal axis, the first jaw element  122  has the same round feature  134  as the second jaw element  124  but has been rotated  180  degrees about its longitudinal axis. 
         [0061]    Two cables  120   w,    120   x  engage the round feature of the first jaw element  122 . The other two cables  120   y,    120   z  engage the round feature  135  of the second jaw element  124 . It is understood that the cable  120   y  follows a path that mirrors the path of cable  120   w.  When cables  120   w  and  120   z  are retracted, the first and second jaw elements  122 , 124  are moved to an open position. When cables  120   x  and  120   y  are retracted, the first and second jaw elements  122 ,  124  are moved to a closed position. 
         [0062]    Opposed constraining links  136 , 138  each has a distal transverse post received in corresponding openings  137 ,  139  at the proximal ends of the first and second jaw elements  122 ,  124 . A sliding pin  140  connects the constraining links  136 ,  138  via slots  142  in the ears  127  of the jaw base  126 . The constraining links  136 ,  138  can thus translate in a longitudinal direction within the slots relative to the jaw base  126 . Specifically, when the first jaw element  122  rotates in a clockwise direction, the first constraining link  136  rotates such that the sliding pin  140  translates longitudinally in the slots  142  in a distal direction. This will in turn similarly move the second constraining link  138  causing the second jaw element  124  to rotate in a counterclockwise direction. Thus, the described configuration of the linkage system constrains the first and second jaw elements  122 , 124  such that they may only move in opposite directions. 
         [0063]    The jaw base  126  is mounted to a distal end  130  of the distal joint  108 . The proximal end  132  of the distal joint  108  is in turn mounted to the distal end of the tube  106 . The proximal joint  104  and the distal joint  108  are operatively connected with the cables  120   w,    120   x,    120   y,    120   z  such that movement of the proximal joint  104  controls the movement of the distal joint  108 . The proximal joint  104  and the distal joint  108  may be joints that allow pivoting about two intersecting, perpendicular axes, and provide two degrees of freedom, being free to move in any combination of directions deflecting relative to the longitudinal axis of the tube  106 , such as, for example, a ball-and-socket joint. 
         [0064]      FIGS. 9-12  show the structure of the distal joint  108 . The components of the proximal joint  104  are identical to the components of the distal joint  108 . However, a proximal joint ball  194  and a distal joint ball  150  face opposite directions in use, such that they mirror each other. All components of both the proximal and distal joints  104 ,  108  are symmetric about perpendicular longitudinal planes. As seen in  FIGS. 9-12 , the distal joint  108  is a ball-and-socket joint comprising a distal end base  130 , a ball  150  and a proximal end base  132 . The ball  150  ( FIGS. 13-16 ) has a proximal slot  152  and an opposed distal slot  154  which is perpendicular to the proximal slot  152 . The proximal slot  152  receives a central axial tab  156  extending distally from the proximal end base  132  for engaging a round feature  158  in the slot  152 . The end of the tab  156  has a corresponding curved surface for smooth movement against the round feature  158  in the ball  150 . In this arrangement, the ball  150  can pivot relative to the proximal end base  132  about a primary axis perpendicular to the longitudinal axis of the round feature  158 . The distal end base  130  has a similar central axial tab  160  extending proximally from the distal end base  130 . The end of the tab  160  has a curved surface that engages and moves against a second round feature  162  in the slot  154 . The distal end base  130  may thus pivot relative to the ball  150  about a secondary axis perpendicular to the second round feature  162  in the ball  150 . This configuration of cooperating tabs and slots for modifying a standard ball-and-socket joint allows for precise linear control of the relative position of the components, as well as improved transmission of torsional motion as compared with a standard ball-and-socket joint. It is understood that the ball  150  need not be a ball shape, but may be any configuration that provides articulation of the components about two perpendicular axes, which may be intersecting axes as configured, and may include round features. 
         [0065]    Referring to  FIG. 17 , the control cables  120   w,    120   x,    120   y,    120   z  extend proximally from the end effector  110  and through two openings  164  in the distal end base  130  of the distal joint  108 . The openings  164  are radially spaced from opposite sides of the central axial tab  160 . The ball  150  defines a continuous oval groove  166  in the surface of the ball  150 . The groove  166  functions as a cable guide. The ball  150  is symmetric about both its central perpendicular planes such that the groove  166  presents identical features functioning as cable guides on the opposite faces of the ball  150 . 
         [0066]    The control cable  120   w  exits a slot in the jaw base  126  and enters an opening  164  in the distal end base  130  of the distal joint  108 . The control cable  120   w  passes around the groove  166  on the bottom surface and side of the ball  150  and passes through an opening  168  in the proximal end base  132  of the distal joint  108 . After exiting the distal joint  108 , the control cable  120   w  continues through an opening  170  in the distal end base  190  of the proximal joint  104 , along a groove  174  in a ball  194  and through an opening  172  in the proximal end base  192  of the proximal joint  104 . 
         [0067]    The control cable  120   x  exits the same slot in the jaw base  126  as control cable  120   w  and enters the opposite opening  164  in the distal end base  130  of the distal joint  108 . The control cable  120   x  passes around the groove  166  on top of the ball  150  and passes through the same opening  168  in the proximal end base  132  of the distal joint  108  as control cable  120   w.  After exiting the distal joint  108 , the control cable  120   x  continues through the same opening in the distal end base  190  of the proximal joint  104 . The control cable  120   x  passes over the groove  174  in the proximal ball  194  and through an opening  172  in the proximal end base  192  of the proximal joint  104  opposite from the opening for the control cable  120   w.    
         [0068]    Control cable  120   y  exits a slot in the jaw base  126  opposite the slot passing the control cables  120   w,    120   x.  The control cable  120   y  passes through the same opening  164  in the distal end base  130  as the control cable  120   w.  The control cable  120   y  passes around the groove  166  on the bottom surface and side of the ball  150  and passes through an opening  168  in the proximal end base  132  opposite the opening passing the control cables  120   w,    120   x.  After exiting the distal joint  108 , the control cable  120   y  continues through an opening  170  in the distal end base  190  of the proximal joint  104 . The opening  170  in the proximal end base  192  is opposite the opening passing the control cables  120   w ,  120   x.  The control cable  120   y  passes over the groove  174  in the proximal ball  194  and through an opening  172  in the proximal end base  192  of the proximal joint  104  which is the same opening for passing the control cable  120   w.    
         [0069]    Control cable  120   z  exits the same slot in the jaw base  126  as control cable  120   y  and passes through the same opening  164  in the distal end base  130  as control cable  120   x.  The control cable  120   z  passes in the groove  166  around the ball  150  and through the same opening in the proximal end base  132  of the distal joint  108  as the control cable  120   y.  After exiting the distal joint  108 , the control cable  120   z  continues through the same opening  170  in the distal end base  190  of the proximal joint  104  as the control cable  120   y.  The control cable  120   z  passes over the ball  194  in the groove  174  and through the same opening  172  in the proximal end base  192  of the proximal joint  104  as the control cable  120   x.    
         [0070]      FIGS. 18 and 19  show the structure of the proximal end of the surgical instrument  100 , including the interface or manipulator assembly  102 . The manipulator assembly  102  comprises a handle  180  and a trigger  182  which is pivotally mounted to the handle  180  by a pin  184  that allows the trigger  182  to rotate about the pin  184 . The trigger  182  is biased into a first home position by a spring  186 . 
         [0071]      FIGS. 20-22  depict the manner in which the motion of the proximal joint  104  and the distal joint  108  and the control cables  120   w,    120   x,    120   y,    120   z  combine to control articulation of the end effector  110 . If control cables  120   x  and  120   z  are fixed relative to the proximal end base  192  of the proximal joint  104 , then rotating the proximal end base  192  and the ball  194  of the proximal joint  104  about its primary axis will retract control cables  120   z  and  120   z  in the tube  106  portion of the surgical instrument  100 . This will cause a corresponding rotation of the distal ball  150  and the proximal end base  132  of the distal joint  108 . The end effector  110  will be unaffected by retraction of these cables due to the constraints applied by the linkage system. 
         [0072]    If control cables  120   y  and  120   z  are fixed relative to the proximal end base  192  of the proximal joint  104 , then rotating the proximal end base  192  about the secondary axis of rotation will retract control cables  102   y  and  120   z  in the tube  106  section of the surgical instrument  100 , which will cause a corresponding rotation of the distal end base  130  of the distal joint  104 . If cables  120   w  and  120   z  are retracted, this will not affect either the proximal joint  104  or the distal joint  108  since the control cables  120   w  and  120   z  are diagonally opposed and would act in opposition to one another to control either axis of motion of the proximal and distal joints  104 ,  108 . This retraction produces an opening motion in the jaw elements  122 , 124  of the end effector assembly  110 . 
         [0073]      FIGS. 23 and 24  show two positions of the interface assembly  102  for producing the described cable retractions. After the control cables  120   w,    120   x,    120   y ,  120   z  exit the proximal end base  192 , the control cables  120   w,    120   x,    120   y,    120   z  enter the handle  180  and are connected to the trigger  182 . Control cables  120   w  and  120   z  are connected at the top of a round feature  183  of the trigger  182 . Control cables  120   x  and  120   y  are connected at the bottom of the round feature  183 . If the trigger  182  is rotated clockwise to a closed position ( FIG. 24 ), control cables  120   x  and  120   y  are retracted, which closes the jaw elements  122 ,  124 . If the trigger  182  is rotated counterclockwise to an open position ( FIG. 23 ), control cables  120   w  and  120   z  are retracted, which opens the jaw elements  122 ,  124 . If the interface  102  and proximal end base  192  are rotated about the primary axis of the proximal joint  104 , control cables  120   x  and  120   z  are retracted, as previously described. This will have no effect on the interface  102  as control cables  120   x  and  120   z  are in opposition to one another relative to the motion of the trigger  182 . Similarly, motion about the secondary joint axes will not affect the interface  120  because control cables  120   y  and  120   z  are in opposition to each other relative to the motion of the trigger  182 . 
         [0074]      FIGS. 25-28  show an alternate embodiment of a ball-and-socket joint, generally designated at  200 , for use in the surgical instrument  100 . In this embodiment, a proximal end base  202  has a central axial passage  204  through a central, distally extending tab  206  to allow passage of a fifth central control cable  208 . Similarly, the ball  205  has a pass through opening  207  and the distal end base  210  defines a central axial passage  212  through a central proximally extending tab  214 . The series of openings through the components allow the central control cable  208  to pass completely through the joint  200 . 
         [0075]    Referring to  FIGS. 29-31 , the four control cables  120   w,    120   x,    120   y,    120   z  are used to control the proximal joint  220  and the distal joint  222  in a manner identical to the previous embodiment described hereinabove. The ends of the control cables  120   w,    120   x ,  120   y,    120   z  terminate in the distal end base  224  of the distal joint  222  and the interface handle  182 . 
         [0076]    In the embodiment shown, a first jaw element  226  and a second jaw element  228  of an end effector assembly  230  are controlled by the central control cable  208  passing through the central axis of the joints  220 ,  222 . Referring to  FIG. 30 , the jaw elements  226 ,  228  of the end effector assembly  230  are pivotally connected by a pin mounted in holes in ears of a jaw base  134 . A jaw driver  136  comprises a transverse pin  137  extending through longitudinal slots in the proximal ends of the jaws  126 ,  128 . The ends of the pin  137  are received in opposed slots  140  in the ears of the jaw base  234 . The driver  236  is thus able to reciprocate relative to the jaw base  234  in a longitudinal direction. The driver  236  is distally biased by a spring  242  disposed between the jaw base  234  and the driver  236 . The distal end of the central control cable  208  is connected to the driver  236 . When the driver  136  translates longitudinally proximally, the jaws  226 ,  228  close ( FIG. 29 ). When the driver  236  translates longitudinally distally the jaws  226 ,  228  open ( FIG. 31 ). The translation of the driver  236  is controlled by the central control cable  208 , which is in turn controlled by the trigger ( FIG. 32 ). Thus, in this embodiment, only one cable  208  is needed to control the position of the jaw elements  226 ,  228 . 
         [0077]    In all embodiments described herein, the control cables may be affixed at their termination point by welding or other fusion method, by adhesive, or by swaging. For example, holes may be drilled in the trigger  182  to facilitate the swaging or adhesive attachment methods. Similar attachment methods may be used to attach the central control cable  208  to the driver  236 . Other attachment methods may also be utilized depending on the material of the cables and other components of the surgical instrument  100 . 
         [0078]      FIGS. 33 and 34  show a distal end  252  and a proximal end  254 , respectively, of a hybrid actuation system  250 . The hybrid actuation system uses both cables and solid rods to control the surgical instrument  100  described in the first embodiment. In the hybrid actuation system, ends of the four control cables  120   w,    120   x,    120   y,    120   z  connect to four rods  260   w,    260   x,    260   y,    260   z  positioned intermediate the lengths of the cables. Holes may be drilled in the ends of the rods  260   w,    260   x,    260   y,    260   z  to facilitate the attachment of the control cables  120   w,    120   x,    120   y,    120   z  by welding or other fusion methods, or by adhesive or swaging. It is understood that other suitable methods of attachment may also be utilized. The control rods  260   w,    260   x,    260   y,    260   z  are slidingly received in a distal guide  262  and a spaced proximal guide  264 , such that the rods  260   w ,  260   x,    260   y,    260   z  can reciprocate longitudinally relative to the guides  262 ,  264  in a proximal and or a distal direction. The operation and function of the surgical instrument  100  is unaffected by this configuration. However, backlash may be reduced by the using the rigid rods  260   w,    260   x,    260   y,    260   z  to replace most of the lengths of control cables in the hybrid actuation system  250 . 
         [0079]    As described hereinabove, the distal joint  108  and the end effector  110  articulate in a direction opposite the direction of articulation of the interface assembly  102  and the proximal joint  104 . This arrangement maintains a constant orientation of the end effector  110  relative to the interface assembly  102 , providing simple control to the user. It is understood that the degree of articulation shown in the FIGs. is meant for demonstrative purposes and is not an indication of any limitation of the design. It is also understood that the design of the end effector in the first embodiment herein is meant to be generalized to any assembly utilizing four control cables for actuation which is constrained such that the first and second jaw elements  126 ,  128  may only move in opposite directions and may produce motion in a plurality of objects, which include but are not limited to cauterizing contacts, pliers, and scissor blades. It is further understood that the design of the end effector  230  in the second embodiment described herein is meant to be generalized to any assembly utilizing a single cable for actuation and for producing motion of a plurality of objects, which include but are not limited to cauterizing contacts, pliers, and scissor blades. 
         [0080]    Although the surgical instrument  100  has been shown and described in considerable detail with respect to only a few exemplary embodiments thereof, it should be understood by those skilled in the art that I do not intend to limit the surgical instrument  100  to the embodiments since various modifications, omissions and additions may be made to the disclosed embodiments without materially departing from the novel teachings and advantages of the surgical instrument  100 , particularly in light of the foregoing teachings. Accordingly, I intend to cover all such modifications, omissions, additions and equivalents as may be included within the spirit and scope of the description and surgical instrument as defined by the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.