Abstract:
A medical instrument tool or end effector constructed of a fixed jaw having a distal grasping end and a proximal body end; a movable jaw having a distal grasping end and a proximal body end; a slide member controlled from a tool actuator, adapted for linear translation and supported between the jaws; at least one link that inter-couples between the slide member and the movable jaw; and a pivot member mounted at the fixed jaw and for engagement with a slot in the body end of the movable jaw.

Description:
RELATED CASES 
     Priority for this application is hereby claimed under 35 U.S.C. §119(e) to commonly owned and U.S. Provisional Patent Application Nos. 61/466,999 which was filed on Mar. 24, 2011 and 61/482,397 which was filed on May 4, 2011 each of which were filed in the name of William J. Peine and Andres Chamorro, and each of which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an end effector or tool construction that is used with a surgical instrument. More particularly, the present invention relates to an improved end effector construction that enables the end effector jaws to close in a more parallel manner. 
     BACKGROUND OF THE INVENTION 
     An end effector that employs a multiple bar linkage is known. One reason for using a structure of this type is to enable the jaws of the end effector to be closed in a more parallel manner. However, present end effectors of this type are not effective in providing a uniform grasping action as there is excessive lateral action upon closing the end effector. With existing jaw constructions the jaws travel, upon closing, to provide a significant undesired sheering action where the end effector jaws engage tissue or a vessel. 
     A rudimentary form of a grasper may be considered as consisting of a pair of jaws with a single pivot point and act like a pair of needle nose pliers. This type of closing action puts immense pressure on tissue portions nearest the apex of the jaws with a squeezing action forcing soft tissue outwards towards the ends of the jaws. This type of end effector can cause severe damage to delicate soft tissue. 
     An alternative style of jaws is a parallel jaws mechanism such as shown in  FIGS. 2-7 . This type of jaw mechanism exerts a more even top to bottom clamping pressure on soft tissue but still has a disadvantage in that the top, moveable jaw has a horizontal travel component that can effect a tearing action on soft tissue such as veins as the jaws are closed upon them. The end effector construction shown in  FIGS. 2-7  herein employs a multiple bar linkage for operating the end effector. 
     Reference is now made to  FIGS. 2-4 , which illustrates the fixed jaw  146  and related movable jaw  144 . The end effector  16  includes a main body portion  154  of the fixed jaw  146  that is affixed to the distal end of distal bending member  20 . A protective sheath  98  may be disposed about the distal bendable member  20  to prevents bodily fluids from entering cavities in the distal bending member. A channel  147  is formed in the main body  154  for receiving the moveable jaw  144  therein. The moveable jaw  144  is hinged to the main body  154  by means of two links  156  and  158  which are attached to fixed pivot points on both the moveable and fixed jaws. As illustrated in  FIGS. 2 and 3 , the upper ends of links  156 ,  158  extend into slot  149  formed in the moveable jaw  144  and are joined by pivot pins  162 ,  164  to bores  163 ,  165  in the jaw  144 . The lower ends of links  156 , 158  extend into slot  148  formed at the bottom of channel  147  and are joined by pivot pins  166 , 168  to bores  167 , 169  in the main body  154 . This fixed point linkage arrangement results in significant lateral action as the upper jaw  144  rocks back and forth on links  156  and  158  as can be seen in the sequence views described in  FIGS. 4-7 . 
     The actuation cable  38  is attached at its&#39; proximal end to a slider/ratchet mechanism (not shown) in the handle of a surgical tool that, instead of imparting a proximal pulling motion to cable  38  when the jaw actuation lever is squeezed, imparts a distal pushing motion to cable  38  when the jaw actuation lever is squeezed. The distal end of cable  38  is fixed to yoke  138  which is slidably mounted in the main body  154 . The yoke has tubular boss  139  which rides in guide/bore  155  in the main body  154 . The boss  139  is firmly fixed on the end of cable  38  and is free to slide proximally/distally in the bore  155 . The yoke  138  is coupled with an arm extension  160  at the proximal end of moveable jaw  144  by pin  142 . The extension arm  160  is disposed angularly to the main longitudinal axis of the movable jaw  144 . See, for example,  FIGS. 3-5  where the extension arm  160  has an elongated slot  161 . The pin  142  is force fit in bores  143  in the yoke  138  and passes through, and is free to slide vertically in, the slot  161  in the extension arm  160 . The extension arm  160  thus is free to slide vertically in relation to the yoke  138  so as to accommodate the vertical movements of the moveable jaw as it opens and closes in response to the push/pull action of the cable  38 . The jaws  144 ,  146  have opposing serrations  170  for enhanced the gripping of tissue. 
       FIGS. 4-7  show a sequence of action as the jaws clamp down on an object such as a the illustrated vein V.  FIG. 4  shows the moveable jaw  144  in a fully open position about to close down on the vein V. In this position the tip  174  of the movable jaw  144  is situated a maximum distance D MAX  proximally from the tip  176  of the fixed jaw  146 . As the jaw actuation lever (not shown) is squeezed, the cable  38  is urged distally (arrow  172 ) and the serrations  170  on jaw  144  make contact with a top contact point TCP on vein V while the serrations  170  on jaw  146  make contact with bottom contact point BCP on vein V as shown in  FIG. 5 . As the moveable jaw  144  closes down upon the vein (arrow  178 ) a rolling action is imparted to the vein V as indicated by the vector of arrow  178 . By the time the jaws have closed to the extent illustrated in  FIG. 6  the top contact point TCP has traveled an average distance DAVG in relation to the bottom contact point BCP. This rolling motion in conjunction with the serrations  170  can cause a significant tearing action in any soft tissue and is a major drawback to this type of jaw actuation mechanism. The distance DAVG may be slightly less than DMAX due to the offset of TCP and BCP according to how far distal or proximal they occur along the length of the jaw serrations in relation to the size of the tissue grabbed.  FIG. 7  shows the jaws fully closed without any tissue present. 
     Accordingly, it is an object of the present invention to provide an improved end effector construction, and in particular one that has the jaws of the end effector close without any substantial lateral motion between the jaws. 
     Another object of the present invention is to provide an improved end effector construction with absolute minimum lateral motion between the jaws, and with a structure that is relatively simple, operates effectively and can be manufactured relatively inexpensively. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a parallel jaws end effector of the invention as used on a surgical instrument such as a laparoscopic instrument; 
         FIG. 2  is an enlarged perspective view of an existing parallel jaws end effector by itself; 
         FIG. 3  is an enlarged perspective view of the parallel jaws end effector of  FIG. 2  but with some portions shown in phantom for clarity; 
         FIGS. 4-7  are schematic cross-sectional views of the parallel jaws in a sequence of positions from fully open to completely closed; 
         FIG. 8  is an enlarged perspective view of the parallel jaws end effector of the present invention used on the instrument of  FIG. 1 ; 
         FIG. 9  is an enlarged perspective view of the parallel jaws end effector of  FIG. 8  but with some portions shown in phantom for clarity; 
         FIG. 10  is an exploded perspective view of the end effector of  FIG. 8 ; 
         FIGS. 11-14  are schematic cross-sectional views of the parallel jaws end effector of the present invention in a sequence of positions from fully open to completely closed; 
         FIG. 15  is an enlarged perspective view of an alternate embodiment of the parallel jaws end effector of the present invention; 
         FIG. 16  is an enlarged perspective view of the parallel jaws end effector of  FIG. 15  but with some portions shown in phantom for clarity; 
         FIG. 17  is an exploded view of the end effector of  FIG. 15 ; and 
         FIGS. 18-21  are schematic cross-sectional views of the parallel jaws end effector of  FIGS. 15-17  in a sequence of positions from fully open to completely closed. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a parallel jaws end effector mechanism of the present invention as used on a surgical instrument, such as the instrument described in previously filed and co-pending application Ser. No. 12/661,765 filed on Mar. 3, 2010, and hereby incorporated by reference herein in its entirety. Endoscopic instruments such as the instrument shown in  FIG. 1  are used in a variety of procedures requiring a variety of end effector tools, one of which may be a grasper to manipulate, position or hold delicate body parts such as tissue, veins, etc. during various surgical procedures. The improved parallel jaws mechanism of the present invention effects an absolute minimal horizontal travel component which practically eliminates any lateral tearing action whatsoever as will be describe in greater detail below. 
     With reference to  FIG. 1  there is illustrated a medical instrument  10  that is basically comprised of a handle  12 , proximal bendable member (not shown), instrument shaft  14 , distal bendable member  20  and tool or end effector  16 . The shaft  14  may be considered as having a longitudinal axis U. Similarly, the handle  12  may be considered as having a longitudinal axis T, and the end effector  16  may be considered as having a distal tip axis P. In  FIG. 1  all of the axes U, T and P are in-line. A bending of the handle  12  with respect to the shaft  14  is shown in  FIG. 1  by virtue of the double arrows that show an angle B 1 . This bending at the proximal bendable member causes a corresponding bending at the distal bendable member, via bend control cables (not shown in  FIG. 1 ), resulting in a bend indicated by the double arrows at an angle B 2  between the instrument shaft  14  and end effector  16 . When the handle is bent downwardly, the end effector bends upwardly. The ratio of bending angle is determined by the ratio of the diameters of the proximal bending member and the distal bending member  20 , which, in turn, determines the distance each cable is actuated. 
     With further reference to  FIG. 1 , there are illustrated several different instrument motions indicated by rotational arrows. Rotation arrow R 1  represents the rotation of the rotation knob  24  about handle axis T. This action, in turn, causes a rotation illustrated by rotation arrow R 2  of the shaft about axis U. The rotation knob  24  supports the proximal bendable member  18  which, in turn, supports the instrument shaft  14 . The rotation R 2  is transmitted to rotation R 3  of the end effector  16  about axis P by way of the distal bendable member  20 . The actuation cables are anchored at one end at end effector  16  and at the opposite end at the rotation knob  24 . The cables control, in a push and pull manner, the end effector  16  as it is rotated to keep axis P at its&#39; preset angle that is fixed by the angle locking means  140 . The distal bendable member  20  is generally smaller in diameter than the proximal bendable member and has discs, ribs and slots such as described in the aforementioned Ser. No. 12/661,765. The distal bendable member  20  also preferably has a sheath  98  encasing it to prevent bodily fluids from infiltration. 
     The surgical instrument of  FIG. 1  has a pistol grip style handle  12  with a horn  13  to nestle in the grip of the hand of the surgeon. The shaft portion  14  is inserted through a cannula or port of entry device (not shown) in a patients abdomen and the end effector  16  can be observed with an endoscopic camera and manipulated within the distended abdomen of a patient by using the cannula or port of entry device as a fulcrum for bending action B 1 , B 2  of the handle and end effector. Angle locking mechanism  140  uses an over center lock/release lever  220  to clamp or release the ball  120  in the hub  202  by means of the cinch ring  200 . Locking in the angle of the end effector tool axis P with regard to the shaft axis U frees up the surgeons motions to further manipulate the end effector. 
     A rolling motion can be carried out with the instrument of the present invention. This can occur by virtue of the rotation of the rotation knob  24  relative to the handle  12  about a longitudinal shaft axis. This is represented in  FIG. 1  by the rotation arrow R 1 . When the rotation knob  24  is rotated, in either direction, this causes a corresponding rotation of the instrument shaft  14 . This is depicted in  FIG. 1  by the rotational arrow R 2 . This same motion also causes a rotation of the distal bendable member and end effector  16  about an axis that corresponds to the instrument tip, depicted in  FIG. 1  as about the longitudinal tip or tool axis P. In  FIG. 1  refer to the rotational arrow R 3  at the tip of the instrument. 
     Any rotation of the rotation knob  24 , using the finger indents  31 , while the instrument is locked (or unlocked) maintains the instrument tip at the same angular position, but rotates the orientation of the tip (tool). For a further explanation of the tip rotational feature refer to co-pending application Ser. No. 11/302,654, filed on Dec. 14, 2005, particularly FIGS. 25-28, which is hereby incorporated by reference in its entirety. 
     By pushing the handle  12  further into the cannula or port of entry the surgeon can then place the open jaws in position to close about the target object. The surgeon can then use the jaw clamping means  30  to close the jaws on the target object by squeezing the jaw actuation lever  22 . This squeezing action is translated into a proximal pulling motion of the push/pull cable  38  through a slider mechanism (not shown). A ratcheting action is normally incorporated into the clamping means  30  to hold jaw clamping pressure when the actuation lever  22  is released. A release button  92  is used to release the clamping pressure and a return spring in the slider returns the jaws to a fully open position. A ratchet disengage slide button  318  may also be incorporated into the handle to disable the ratcheting action if so desired. 
     Reference is now made to  FIGS. 8-14  for an illustration of a first embodiment of the improved parallel jaw mechanism of the present invention. A second embodiment of the instrument is illustrated in  FIGS. 15-21 . The first embodiment uses a pulling action for jaw closure while the second embodiment uses a pushing action for jaw closure. The first embodiment is first described. 
     In  FIGS. 8-14  the same reference numbers are used where applicable, as previously identified in the instrument shown in  FIGS. 2-7 , such as the distal bendable member  20 , the tool actuation cable  38 , links  156 ,  158  and pivots  162 ,  164 ,  166  and  168 . Instead of fixed pivot points for the lower ends of links  156 ,  158  (pins  166 ,  168  in  FIG. 2  fixed with the lower jaw  146 ) the end effector construction of the present invention utilizes sliding pivot locations by means of the lower ends of the links  156 ,  158  being supported for translation by engagement with the yoke  180 . The yoke  180  essentially functions as a slide member controlled from the actuation cable  38 . The yoke  180  includes a boss  181  having extending therefrom elongated arms that each include upper arms  182  and lower arms  186  that are interconnected by an angled transition section. The pins  166 ,  168  are received in respective bores  188 , 190  formed in the lower arms  186  of the yoke  180 . As illustrated in  FIG. 10 , the arms  182  and  186  each include a pair of parallel spaced apart arms, with the lower arms  186  each have the respective aligned bores  188 ,  190 . 
     The yoke  180  travels proximally when the cable  38  is pulled (arrow  194  in  FIG. 12 ) to move the end effector jaws toward a closed position. It is to be noted that, while in the prior art embodiment described herein in  FIGS. 2-7 , the actuation cable  38  is pushed distally (see arrow  172  in  FIGS. 5 and 6 ), in the present invention, in the first embodiment described herein, the actuation cable  38  is pulled proximally (see arrows  194  in  FIGS. 12 and 13 ). The closing action involves having the pin  142  ride in the slot  161  of the extension arm  160  for controlling the action of the movable jaw  144 . The extension arm  160  is somewhat elongated, as is the slot  161 , and the extension  160  is integral with and extends substantially orthogonal to the length of the movable jaw  144  and the length of the upper arms  182  such as shown in  FIG. 12 . The action between the cable  38 , yoke  180 , pin  142  and movable jaw  144  causes a substantially parallel closing as illustrated by the arrow  196  in  FIG. 12 . 
     The pin  142  is anchored in bores  192  and serves as a pivot location for the moveable jaw  144  thus controlling the distal travel of the moveable jaw to a relatively flat arc about pin  142  as indicated by the arrow  196 . As illustrated in  FIGS. 9 and 10  the upper ends of links  156 ,  158  extend into a slot  149  in the moveable jaw  144  and are joined by pivot pins  162 ,  164  to bores  163 ,  165  in the jaw  144 . The lower ends of the links however, extend between the spaced apart lower arms  186  of yoke  180  and pivot pins  166 ,  168  join the lower ends of the respective links  156 ,  158  to bores  188 ,  190 . Tilt axis  157  is defined between pins  162  and  166 , while tilt axis  159  is defined between pins  164  and  168 . Pin  168  in this embodiment is longer than pin  166  so as to extend into and ride in the respective slots  150  in the main body  154  of fixed jaw  154 . The slots  150  are provided on opposite sides of the channel  147 . This interlocking between the links and jaws provides a support guide to the yoke  180  as pressure is applied to the moveable jaw  144  as the yoke is slid distally and the jaw closes upon an object. 
     Pivot pin  142  also passes through slots  184  in upper arms  182  of yoke  180  and is force fit in bores  192  in the sides of main body  154  of the fixed jaw  146 . This anchors the pivot pin  142  to the fixed jaw  146 , and provides a pivot location for the moveable jaw, while further providing a support guide for the yoke  180 . The slot  161  of extension arm  160  is elongated allowing the pin  142  to transition along the slot  161  as the slide member moves linearly as the jaws move to a closed position. Note the transition of the pin  142  in slot  161  from  FIG. 11  to  FIG. 14  where the jaws are fully closed. This translation occurs while maintaining the jaws in a parallel relationship with little or no lateral movement. The yoke  180  has a tubular guide or boss  181  which rides in bore  155  in the main body  154  of the fixed jaw  146 . The boss  181  is firmly fixed on the end of cable  38  and is free to slide proximally/distally in the bore  155 . 
       FIGS. 11-13  show a sequence of action as the jaws clamp down on an object such as a vein V.  FIG. 11  shows the moveable jaw  144  in a full open position about to close down on vein V. In this position the tip  174  of the jaw  144  is situated a maximum distance DMAX proximally from the tip  176  of the fixed jaw  146 . As the jaw activation lever  22  of instrument  10  ( FIG. 1 ) is squeezed, the cable  38  is urged proximally (arrow  194 ) and the serrations  170  on jaw  144  make contact with top contact point TCP on vein V. as this occurs, the serrations  170  on jaw  146  make contact with bottom contact point BCP on vein V as shown in  FIG. 12 , squeezing down on the vein V. As the moveable jaw  144  closes down on the vein (arrow  196 ) very little rolling (lateral) action is imparted to the vein V as can be seen by the vector of the arrow  196 . When the jaws have closed upon the vein V to the extent shown in  FIG. 13  the TCP has traveled an average distance DAVG in relation to the point BCP. This greatly reduced rolling motion and practically eliminates any tearing action on soft tissue.  FIG. 14  shows the jaws fully closed without any tissue present. 
     There are described herein two basic embodiments of the present invention. The first embodiment that has just been described employs a pulling action that does have the advantage of being able to impose a greater closing force. However, the principles of the present invention also apply to an end effector construction wherein a pushing action is used. This embodiment is now described in  FIGS. 15-21 . 
     In  FIGS. 15-21  the same reference numbers are used, as previously identified in the instrument shown in  FIGS. 8-14 , such as the distal bendable member  20 , the tool actuation cable  38 , links  156 ,  158  and pivots  162 ,  164 ,  166  and  168 . Instead of fixed pivot points for the lower ends of links  156 ,  158  the end effector construction of the present invention utilizes sliding pivot locations by means of the lower ends of the links  156 ,  158  being supported for translation by engagement with the yoke  180 . The yoke  180  essentially functions as a slide member controlled from the actuation cable  38 . The yoke  180  includes a boss  181  having extending therefrom elongated arms that each include upper arms  182  and lower arms  186  that are interconnected by an angled transition section. The pins  166 ,  168  are received in respective bores  188 , 190  formed in the lower arms  186  of the yoke  180 . As illustrated in  FIG. 17 , the arms  182  and  186  each include a pair of parallel spaced apart arms, with the lower arms  186  each have the respective aligned bores  188 ,  190 . 
     The yoke  180  travels distally when the cable  38  is pushed (arrow  198  in  FIG. 19 ) to move the end effector jaws toward a closed position. This closing action involves having the pin  142  ride in the slot  161  of the extension arm  160  for controlling the action of the movable jaw  144 . The extension  160  is somewhat elongated, as is the slot  161 , and the extension  160  is integral with and extends substantially orthogonal to the length of the movable jaw  144  and the length of the upper arms  182  such as shown in  FIG. 18 . The action between the cable  38 , yoke  180 , pin  142  and movable jaw  144  causes a substantially parallel closing like that illustrated by the arrow  196  in  FIG. 12 . The result is that there is little or no lateral action between the respective jaws upon jaw closure. 
     The pin  142  is anchored in bores  192  and serves as a pivot location for the moveable jaw  144  thus controlling the distal travel of the moveable jaw to a relatively flat arc about pin  142  alike that indicated by the arrow  196  in  FIG. 12 . As illustrated in  FIGS. 16 and 17  the upper ends of links  156 ,  158  extend into a slot  149  in the moveable jaw  144  and are joined by pivot pins  162 ,  164  to bores  163 ,  165  in the jaw  144 . The lower ends of the links however, extend between the spaced apart lower arms  186  of yoke  180  and pivot pins  166 ,  168  join the lower ends of the respective links  156 ,  158  to bores  188 ,  190 . Tilt axis  157  is defined between pins  162  and  166 , while tilt axis  159  is defined between pins  164  and  168 . Pin  168  is preferably longer than pin  166  so as to extend into and ride in the respective slots  150  in the main body  154  of fixed jaw  154 . The slots  150  are provided on opposite sides of the channel  147 . This interlocking between the links and jaws provides a support guide to the yoke  180  as pressure is applied to the moveable jaw  144  as the yoke is slid distally and the jaw closes upon an object. 
     Pivot pin  142  also passes through slots  184  in upper arms  182  of yoke  180  and is force fit in bores  192  in the sides of main body  154  of the fixed jaw  146 . This anchors the pivot pin  142  to the fixed jaw  146 , and provides a pivot location for the moveable jaw, while further providing a support guide for the yoke  180 . The slot  161  is elongated allowing the pin  142  to transition along the slot  161  as the slide member moves linearly as the jaws move to a closed position. Note the transition of the pin  142  in slot  161  from  FIG. 18  to  FIG. 21  where the jaws are fully closed. This translation occurs while maintaining the jaws with little or no lateral movement. The yoke  180  has a tubular guide or boss  181  which rides in bore  155  in the main body  154  of the fixed jaw  146 . The boss  181  is firmly fixed on the end of cable  38  and is free to slide proximally/distally in the bore  155 . 
       FIGS. 18-21  show a sequence of action as the jaws clamp down on an object such as a vein V.  FIG. 18  shows the moveable jaw  144  in a full open position about to close down on vein V. In this position the tip  174  of the jaw  144  is situated a maximum distance DMAX proximally from the tip  176  of the fixed jaw  146 . As the jaw activation lever  22  of instrument  10  ( FIG. 1 ) is squeezed, the cable  38  is urged distally (arrow  198 ) and the serrations  170  on jaw  144  make contact with top contact point TCP on vein V. As this occurs, the serrations  170  on jaw  146  make contact with bottom contact point BCP on vein V like that shown in  FIG. 12 , squeezing down on the vein V. As the moveable jaw  144  closes down on the vein very little rolling (lateral) action is imparted to the vein V. When the jaws have closed upon the vein V to the extent shown in  FIG. 20  the TCP will have traveled an average distance DAVG in relation to the point BCP. This greatly reduced rolling motion and practically eliminates any tearing action on soft tissue.  FIG. 21  shows the jaws fully closed without any tissue present. 
     As can be seen in the sequential views of  FIGS. 18-21 , the axes  157 ,  159  respectively of links  156 ,  158  shift along with the lower pivot points (bores  188 ,  190 ) from a more proximal position (jaws open) relative to upper pivot points (pins  162 , 164 ) to more distal position (jaws closed) relative to the upper pivot points (pins  162 ,  164 ) as the cable  38  is pushed distally. To state this in another way, and in connection with the sequential views of  FIGS. 18-21 , as the jaws move from an open position to a closed position, the axes  157 ,  159  tilt from a left position relative to the pins  166 ,  168 , to a right position relative to the pins  166 ,  168 . This is the reverse action of the pull version of the instrument illustrated  FIGS. 11-14 . In  FIGS. 11-14 , the axes  157 ,  159  respectively of links  156 ,  158  shift along with the lower pivot points (bores  188 ,  190 ) from a more distal position (jaws open) relative to upper pivot points (pins  162 , 164 ) to more proximal position (jaws closed) relative to the upper pivot points (pins  162 ,  164 ) as the cable  38  is pulled distally. To state this in another way, and in connection with the sequential views of  FIGS. 11-14 , as the jaws move from an open position to a closed position, the axes  157 ,  159  tilt from a right position relative to the pins  166 ,  168 , to a left position relative to the pins  166 ,  168 . 
     Having now described embodiments of the present invention, it should now be apparent to one skilled in the art that there are numerous other embodiments, and modifications thereof, that are anticipated as falling within the scope of the present invention. For example, the end effector construction described herein has been explained as associated with a pistol grip instrument. However, the end effector construction may also be used with a variety of other instrument constructions including, but not limited to, straight instruments as well as articulating instruments. The particular end effector construction may also be used in surgical robotics, wherein there may be motorized control and/or tele-operated control. Another variation is that the profile of the motion can be readily changed by adjusting the lengths of the links  156 ,  158 . Also, the locations of the pivot points for the links can be varied. For example, the pivot points (pins  162 ,  164 ,  166  and  168 ) may be adjusted so that the tip of the jaws close first, or slightly before the remainder of the jaw surfaces  170  fully close. In the drawings the slot  161  is illustrated as straight. However, the slot  161  can also have other configurations such as an arcuate shape. The previous description references the grasping of a vessel, but the end effector can also be used in an application of vessel sealing, or other surgical procedure applications.