Abstract:
An end effector for a surgical instrument includes a fixed bearing member, having an end effector axis defined therethrough, with mounting surfaces for attachment to a distal end of the surgical instrument. An input shaft is configured for rotational motion relative to the fixed bearing member about the end effector axis and a force transfer member is coupled to the input shaft such that rotary motion of the input shaft generates longitudinal motion in the force transfer member. At least one jaw member couples to the force transfer member such that longitudinal motion of the force transfer member results in the jaw member moving between an open and a closed configuration relative to an opposing jaw member.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to an apparatus for remotely activating jaw members on an articulating surgical instrument. In particular, the apparatus provides an end effector capable of transferring a sufficient force to the jaw members to cause a therapeutic effect on tissue clamped between the jaw members. 
         [0003]    2. Background of Related Art 
         [0004]    Typically in a laparoscopic, an endoscopic, or other minimally invasive surgical procedure, a small incision or puncture is made in a patient&#39;s body. A cannula is then inserted into a body cavity through the incision, which provides a passageway for inserting various surgical devices such as scissors, dissectors, retractors, or similar instruments. To facilitate operability through the cannula, instruments adapted for laparoscopic surgery typically include a relatively narrow shaft supporting an end effector at its distal end and a handle at its proximal end. Arranging the shaft of such an instrument through the cannula allows a surgeon to manipulate the proximal handle from outside the body to cause the distal end effector to carry out a surgical procedure at a remote internal surgical site. This type of laparoscopic procedure has proven beneficial over traditional open surgery due to reduced trauma, improved healing and other attendant advantages. 
         [0005]    An articulating laparoscopic or endoscopic instrument may provide a surgeon with a range of operability suitable for a particular surgical procedure. The instrument may be configured such that the end effector may be aligned with an axis of the instrument to facilitate insertion through a cannula, and thereafter, the end effector may be caused to articulate, pivot or move off-axis as necessary to appropriately engage tissue. When the end effector of an articulating instrument comprises a pair of jaw members for grasping tissue, a force transmission mechanism such as a flexible control wire may be provided to open or close the jaws. For example, the control wire may extend through an outer shaft from the handle to the jaws such that the surgeon may create a tension in the control wire to cause the jaws to move closer to one another. The closure or clamping force generated in the jaws may be directly related to the tension in the control wire applied by the surgeon. 
         [0006]    One type of laparoseopic or endoscopic instrument is intended to generate a significant closure force between jaw members to seal small diameter blood vessels, vascular bundles or any two layers of tissue with the application electrosurgical or RF energy. The two layers may be grasped and clamped together by the jaws of an electrosurgical forceps, and an appropriate amount of electrosurgical energy may be applied through the jaws. In this way, the two layers of tissue may be fused together. The closure forces typically generated by this type of procedure may present difficulties when using a typical control wire to open and close the jaws of an articulating instrument. 
         [0007]    For example, a surgeon&#39;s efforts to position the jaws may be frustrated by a tendency for a control wire under tension to realign the jaws with the axis of the instrument after the jaws have been articulated off-axis. Although this tendency may be observed in any type of articulating instrument, the tendency is particularly apparent when the closure forces and necessary tension in the control wire are relatively high, as is common in an electrosurgical sealing instrument. This tendency may be created by the direction of reaction forces through the outer shaft of the instrument. 
       SUMMARY 
       [0008]    The present disclosure describes an end effector for incorporation into an articulating surgical instrument, which decouples a force application mechanism from an outer shaft of the instrument. The end effector includes a fixed bearing member, which defines an end effector axis and provides mounting surfaces for attachment to a distal end of the surgical instrument. An input shaft is configured for rotational motion relative to the fixed bearing member about the end effector axis, and a force transfer member is coupled to the input shaft such that rotary motion of the input shaft generates longitudinal motion in the force transfer member. At least one jaw member is coupled to the force transfer member such that longitudinal motion of the force transfer member results in the at least one jaw member moving relative to an opposing jaw member between an open configuration and a closed configuration. 
         [0009]    The force transfer member may include proximal flanges disposed thereon, which abut a proximal face of the at least one jaw member when the at least one jaw member is in the closed configuration. A reactive member may be coupled between the fixed bearing member and the at least one jaw member that is adapted to contain a reactive force within the end effector. The reactive member may include a pivot boss about which the at least one jaw member pivots during movement from the open and closed configurations. 
         [0010]    One of the force transfer member and the at least one jaw member may include a cam pin and the other of the force transfer member and the at least one jaw member may include a cam slot such that the cam pin engages the cam slot to pivot the at least one jaw member about the pivot boss. 
         [0011]    The force transfer member may engage a proximal face of the at least one jaw member when the at least one jaw member is in a nearly closed configuration. The input shaft may be coupled to a power screw and the force transfer member may be coupled to a translation nut such that the translation nut translates longitudinally upon rotational motion in the power screw. The at least one jaw member may include a pair of moveable jaws. 
         [0012]    According to another aspect of the disclosure, an end effector for a surgical instrument comprises a fixed member defining an end effector axis and providing mounting surfaces for attachment to a distal end of the surgical instrument. A pair of jaw members is configured to move between an open and a closed configuration, and a force transfer member is configured for longitudinal motion with respect to the fixed member along the end effector axis. The force transfer member is configured to contact at least one the jaw members of the pair of jaw members and transfer a longitudinal force thereto when the pair of jaws is in the closed configuration. A reactive member is coupled to the fixed member and to the at least one of the jaw members of the pair of jaw members such that a reactionary force resulting from the force transferred to the at least one jaw member of the pair of jaw members is realized in the reactive member. 
         [0013]    According to another aspect of the disclosure, a surgical instrument incorporating an end effector as described above may comprise a handle portion near a proximal end for manipulation by a surgeon to control the surgical instrument, and a tubular shaft extending distally from the handle portion to define an instrument axis. The end effector may be pivotally coupled to a distal end of the tubular shaft such that the end effector may articulate relative to the instrument axis. The surgical instrument may further comprise a torsion cable or rod coupled to end effector to deliver rotational motion thereto. 
         [0014]    According to another aspect of the disclosure, a method for approximating a pair of jaws on a surgical instrument comprises the steps of providing an instrument which includes a cam pin and a corresponding cam slot for moving at least one jaw member from an open configuration to a nearly-closed configuration with respect to an opposed jaw member, where the instrument further comprises a force transfer member for engaging the at least one jaw member to move the at least one jaw member form the nearly-closed configuration to a closed configuration, moving the cam with respect to the cam slot to move the at least one jaw member to the nearly-closed configuration, and advancing the force transfer member with respect to the at least one jaw member when the jaw member is in the nearly-closed configuration such that the force transfer member engages the at least one jaw member and moves the at least one jaw member to the closed configuration. The method may also comprise the step of at least partially disengaging the cam pin from the cam slot when the at least one jaw is in the nearly closed configuration. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the detailed description of the embodiments given below, serve to explain the principles of the disclosure. 
           [0016]      FIG. 1A  is a perspective view of an articulating laparoscopic surgical instrument that may incorporate the features of the present disclosure; 
           [0017]      FIG. 1B  is a perspective view of an embodiment of an articulating surgical instrument according to one embodiment of the present disclosure; 
           [0018]      FIG. 2A  is a perspective view of an end effector in accordance with an embodiment of the present disclosure in an open configuration; 
           [0019]      FIG. 2B  is a perspective view of the end effector of  FIG. 2A  in a closed configuration; 
           [0020]      FIG. 3  is a top view of the end effector of  FIG. 2A  in the open configuration; 
           [0021]      FIG. 4A  is a side view of the end effector of  FIG. 2A  in the open configuration; 
           [0022]      FIG. 4B  is a side view of the end effector of  FIG. 2A  in the closed configuration; 
           [0023]      FIG. 5A  is an enlarged, side view of a pivoting portion of the end effector of  FIG. 2A  in a nearly closed configuration; 
           [0024]      FIG. 5B  is an enlarged, side view of the pivoting portion of the end effector of  FIG. 2A  in the closed configuration; 
           [0025]      FIG. 6A  is a partial top view of an alternate embodiment of an end effector in accordance with the present disclosure; 
           [0026]      FIG. 6B  is a side view of the end effector of  FIG. 6A ; 
           [0027]      FIG. 7A  is a top view of another alternate embodiment of an end effector in accordance with the present disclosure; 
           [0028]      FIG. 7B  is a side view of the end effector of  FIG. 7A  in an open configuration; and 
           [0029]      FIG. 7C  is a side view of the end effector of  FIG. 7A  in a closed configuration. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    Referring initially to  FIG. 1A , an articulating endoscopic instrument is depicted generally as  10 . The instrument  10  includes a handle portion  12  near a proximal end, an end effector  16  near a distal end and an elongated shaft  18  therebetween. Elongated shaft  18  defines an instrument axis “A 1 ” to which end effector  16  aligns for insertion through a cannula (not shown) or other suitable introducer. End effector  16  is articulatable off-axis (as indicated in phantom) to appropriately engage tissue. Handle portion  12  is manipulatable by the surgeon from outside a body cavity to control the movement of the end effector  16  positioned inside the body at a tissue site. For example, the surgeon may separate and approximate a pivoting handle  20  relative to a stationary handle  22  to respectively open and close jaw members  24 ,  26 . Also, a surgeon may pivot lever  30  to cause the end effector  16  to articulate or pivot in a horizontal plane about a pivot pin  32 . A more complete description of the components and operation of instrument  10  may be found in U.S. Patent Application Publication No. 2006/0025907 to Nicholas et al. 
         [0031]    Another type of known articulating surgical instrument is depicted generally as  40  in  FIG. 1B . Instrument  40  includes a handle portion  42  that is manipulatable to control the movement of end effector  46 . Handle portion  42  is coupled to end effector  46  through a flexible shaft  48  that moves into and out of alignment with instrument axis “A 2 .” 
         [0032]    Both articulating instruments  10 ,  40  provide for off-axis operation of the respective end effectors  16 ,  46 . Both instruments  10 ,  40  may exhibit a tendency to align themselves to the respective instrument axes A 1 , A 2  when the end effectors  16 ,  46  are operated if the instruments  10 ,  40  are equipped with a force transmission mechanism that generates reaction forces in outer shafts  18 ,  48 . Accordingly, an end effector  100  as described below may be incorporated into instruments similar to instruments  10 ,  40  to decouple any reactionary forces from outer shafts of the instruments. End effectors in accordance with the present disclosure may also be incorporated into a non-articulating instrument. 
         [0033]    Referring now to  FIGS. 2A through 5B , an end effector in accordance with the present disclosure is depicted generally as  100 . End effector  100  includes jaw members  102  and  104  that are selectively movable between an open configuration as seen in  FIG. 2A  and a closed configuration as depicted in  FIG. 2B . This motion of the jaw members  102 ,  104  is achieved upon the application of a torsion force to end effector  100 . Therefore, a control wire placed in tension, which as discussed above may generate reactionary forces in the outer shaft of an instrument and tend to frustrate the articulation of the instrument, is not necessary. 
         [0034]    End effector  100  is adapted to receive a torsion force through input shaft  106  such that input shaft  106  may rotate about an end effector axis “e” as indicated by arrows “r.” Input shaft  106  includes a bore  108  ( FIG. 3 ), which provides connectivity to a suitable external source of rotational motion (not shown). The rotational motion may be generated, for example, by an electric motor, or alternatively by a surgeon using a manual control surface at a handle portion of the instrument. If the rotational motion is generated in a handle portion of the instrument, a flexible torsion cable (shown in phantom in  FIG. 3 ) may be positioned through the instrument shaft to transmit rotational motion from the handle to the end effector  100 . 
         [0035]    Input shaft  106  rotates inside a fixed bearing member  110 . Fixed bearing member  110  provides mounting surfaces for direct or indirect fixed coupling to an articulating distal end of an instrument shaft, which remains stationary relative thereto. In this way, the entire end effector  100  is supported by the instrument and may be caused to articulate relative to an instrument axis. Fixed bearing member  110  also supports a reactive member  114  on an outer surface thereof. As best seen in  FIG. 3 , reactive member  114  extends distally from fixed bearing member  110  and comprises a pivot boss  118  ( FIG. 3 ) extending into jaw member  102 . Jaw member  102  is pivotable about pivot boss  118  as the end effector  100  is moved between the open and closed configurations. Although removed from the figures for clarity, an additional reactive member  114  is supported by fixed bearing member  110  so as to mirror the reactive member  114  shown and provide a pivot boss  118  about which jaw member  104  may rotate when end effector  100  is moved between the open and closed configurations. Reactive member  114  remains stationary relative to fixed bearing member  110  as jaw members  102 ,  104  pivot open and closed. 
         [0036]    A power screw  120  is supported at a distal end of input shaft  106 . The power screw  120  is coupled to the input shaft  106  such that both the power screw  120  and the input shaft  106  rotate together. Rotation of the power screw  120  drives a translation nut  122  longitudinally along end effector axis “e.” For example, rotation of power screw  120  in a first direction advances translation nut  122  from the position depicted in  FIG. 4A  where the translation nut is disposed at a distance “d” from the fixed bearing member  110 , to the position depicted in  FIG. 4B  where the translation nut  122  is a greater distance “D” from the fixed bearing member  110 . Likewise, rotation of power screw  120  in an opposite direction withdraws translation nut  122  such that translation nut  122  becomes closer to the fixed bearing member  110 . 
         [0037]    A force transfer member  126  is supported at a distal end of translation nut  122 . Force transfer member  126  may be coupled to translation nut  122  or may be formed integrally therewith such that the force transfer member  126  translates along with the translation nut  122 . Force transfer member  126  is formed with a central web  128  having a pair of proximal flanges  130  extending therefrom in opposite directions. The proximal flanges  130  exhibit sloped base portions  132  at their lower ends. An opposed pair of cam pins  134  also protrudes from central web  128 . 
         [0038]    The cam pins  134  work in conjunction with proximal flanges  130  to open and close the jaw members  102 ,  104 . Cam pins  134  engage a pair of cam slots  138  on the jaw members  102 ,  104  as the cam pins  134  translate distally along with force transfer member  126 . Distal translation of cam pins  134  through cam slots  138  cause the jaw members  102 ,  104  to move from the open configuration of  FIG. 4A  to the nearly-closed configuration of  FIG. 5A . In the nearly-closed configuration, the sloped base portions  132  of the proximal flanges  130  contact proximal faces of jaw members  102 ,  104 . Also at the nearly closed configuration, each of the cam pins  134  reach a curve  144  in the respective cam slots  138  that allows force to be transferred from the cam pins  134  to the proximal flanges  130  of the force transfer member  126 . Further distal translation of the force transfer member  126  will move the jaws from the nearly-closed configuration of  FIG. 5A  to the closed configuration of  FIG. 5B  as the sloped base portions  132  press against the proximal faces of the jaw members  102 ,  104 . 
         [0039]    In the closed configuration of  FIGS. 2B ,  4 B and  5 B, the jaw members  102 ,  104  may generate a significant clamping force that can be directed at tissue positioned between the jaw members  102 ,  104 . As the proximal flanges  130  press distally against the jaw members  102 ,  104 , the jaw members  102 ,  104  press distally on the pivot bosses  118  of reactive member  114 . An opposite reaction force is realized as a tensile force in the reactive member  114 , which links the jaw members to the fixed bearing member  110 . Because the reaction force is contained entirely within the end effector  100 , this arrangement allows an articulating instrument to which the end effector  100  is attached to close jaw members  102 ,  104  without creating a tendency for the end effector to conform to an axis of the instrument. 
         [0040]    Referring now to  FIGS. 6A and 6B , an alternate embodiment of an end effector in accordance with the present disclosure is depicted generally as  200 . End effector  200  defines a lever cam arrangement and comprises a jaw member  202 , a reactive member  214 , which supports a pivot boss  218 , and a force transfer member  226 . Jaw member  202  is configured to pivot about pivot boss  218  (as indicated by arrows “p”) in response to longitudinal translation (as indicated by arrows “I”) of the force transfer member  226  at some lateral distance from the pivot boss  218 . End effector  200  may be equipped with an opposing jaw member (not shown), stationary or moveable, such that jaw member  202  is moved between an open and closed configuration as it pivots about pivot boss  218 . The force transfer member  226  is coupled to the jaw member  202  such that distal translation of the force transfer member  226  moves jaw member  202  to the closed configuration, and proximal translation of the force transfer member  226  moves jaw member  202  to the open configuration. 
         [0041]    Reactive member  214  is supported at a proximal end by a fixed member (not shown) as part of a motion conversion mechanism that converts rotational motion to longitudinal motion. For example, a motion conversion mechanism may include an arrangement of a power screw and translation nut as described above. Alternatively, a worm gear arrangement may be configured to drive force transfer member  226  longitudinally relative to reactive member  214 . This arrangement would also allow reactive member  214  to carry reactive forces entirely within the end effector  200 . Reactive member  214 , however, would be placed in compression as jaw member  202  is moved to the closed configuration. 
         [0042]    Referring now to  FIGS. 7A through 7C , another alternate embodiment of an end effector in accordance with the present disclosure is depicted generally as  300 . End effector  300  includes a jaw member  302 , which is movable between an open configuration and a closed configuration as described below. End effector  300  is adapted to receive a torsion force from an external source through input shaft  306 . Input shaft  306  rotates inside a fixed bearing member  310 . Fixed bearing member  310  is coupled to an articulating distal end of an instrument shaft and remains stationary relative thereto. In this way, the entire end effector  300  is supported by the instrument and may be caused to articulate relative to an instrument axis. 
         [0043]    Fixed bearing member  310  also supports a reactive member  314  on an upper surface thereof. Reactive member  314  is formed from a thin strip of conformable material such as spring steel or a shape memory alloy, and extends distally from fixed bearing member  310  to jaw member  302  through a pivot channel  318 . Longitudinal motion of the reactive member  314  through the pivot channel  318  causes reactive member  314  to flex in an upward or downward direction to move jaw member  302  between an open configuration as depicted in  FIG. 7B  and a closed configuration as depicted in  FIG. 7C . 
         [0044]    A power screw  320  is supported at a distal end of input shaft  306  such that both the power screw  320  and the input shaft  306  may rotate together. Rotation of the power screw  320  drives a translation nut  322  longitudinally with respect to fixed bearing member  310 . For example, rotation of power screw  320  in a first direction advances translation nut  322  from the position depicted in  FIG. 7B  where a gap “g” separates translation nut  322  from fixed bearing member  310 , to the position depicted in  FIG. 7C  where a larger gap “G” separates translation nut  322  from fixed bearing member  310 . Likewise, rotation of power screw  320  in an opposite direction withdraws translation nut  322  such that it becomes closer to the fixed bearing member  310 . 
         [0045]    A force transfer member  326  is supported at an upper end of translation nut  322 . Force transfer member  326  may be coupled to translation nut  322  or formed integrally therewith such that the force transfer member  326  translates along with translation nut  322 . Pivot channel  318  is extends entirely through force transfer member  326  at a distal end such that force transfer member  326  exhibits a forked configuration as best seen in  FIG. 7A . When end effector  300  is in the closed configuration depicted in  FIG. 7C , a distal end of the forked force transfer member  326  contacts a proximal face of the jaw member  302 . This allows force to be transferred from the reactive member  314  to the force transfer member  326 . Further distal translation of the translation nut  322  will result in force transfer member  326  pressing against the proximal face of the jaw member  302  such that jaw member  302  may generate a substantial clamping force. When the force transfer member  326  presses against the jaw member  302 , a reaction force is realized as a tensile force in the reactive member  314 . Since the reaction force is contained within the end effector  300 , the closure of jaw member  302  does not tend to frustrate the articulation of an instrument to which end effector  300  is coupled. 
         [0046]    Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims.