Abstract:
A flexible medical instrument includes an elongate shaft, a jaw tip on the distal end of the elongate shaft and a handle on the proximal end. The elongate shaft includes a coil tube having a distal end fixedly attached to a portion of the jaw tip and a proximal end fixedly attached to a rigid structure at the proximal end of the instrument. The coil tube is disposed within an outer sheath that includes a tubular braid. The elongate shaft and jaw tip are axially rotatable relative to the handle for rotational positioning of the jaws. An actuation element is longitudinally moveable within the shaft to open and close the jaws. The sheath prevents or restricts expansion of the coil tube during pushing of the actuation element.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to the field of medical instruments. More particularly, the present invention relates to flexible instruments for use in laparoscopic or endoscopic procedures and which have torque transmissive shafts. 
       BACKGROUND 
       [0002]    Flexible endoscopic surgical dissectors, graspers, forceps etc are conventional instruments used for endoscopic procedures. In a typical embodiment, the device&#39;s jaws are connected to a common clevis pin mounted in a clevis which is coupled to the distal end of a shaft which includes an elongate flexible coil. 
         [0003]    Advances in laparoscopic or single port surgical techniques have created new uses for flexible instruments beyond their traditional endoscopic use. For example, Applicant&#39;s co-pending U.S. application Ser. No. ______, entitled MULTI-INSTRUMENT ACCESS DEVICES AND SYSTEMS, filed Jul. 29, 2009, Attorney Docket No. TRX-2220, describes a multi-instrument access system in which flexible instruments are introduced into the body via deflectable cannulas. In one type of disclosed system, two such deflectable cannulas are disposed through a single access port in a body wall. The deflectable cannulas have actuators at their proximal ends that are responsive to movement of the handles of the instruments disposed in the cannulas. Thus, even though the instruments are not themselves actively deflectable, the user can cause deflection of the distal ends of the instruments by manipulating their handles. 
         [0004]    Conventional flexible instrument suffer from certain drawbacks when used with access technology such as that described in Applicant&#39;s co-pending application. The coil gives the shaft of the device the requisite flexibility for use in a flexible endoscope or other flexible, articulating or non-linear access device. However, the coil shaft is, at best, only torqueable in one direction, since the coil structure renders the shaft vulnerable to twisting when the torque is applied to the instrument, thus limiting the user&#39;s ability to axially rotate the jaws when needed. Moreover, the flexible proximal end of a conventional instrument shafts lack the ability to operatively couple with the actuators of a deflectable cannula of the type described above in a manner that enables the actuator to translate manipulation of the instrument handle into deflection of the distal ends of the instrument cannulas. 
         [0005]    A third drawback, which is found in conventional dissector designs, lies in their inability to deliver adequate forces both when the jaws are being opened to spread tissue and when the jaws are being closed to grasp tissue. With conventional graspers, the pull-wire is pulled to move the jaws to one position (opened or closed), and the pull-wire is pushed to move the jaws to the other position. Pulling the pull-wire places the springs in compression and allows adequate force transmission to the tissue using the jaws. However, when the pull-wire is moved forward, the coils of the spring can separate, thereby reducing the amount of force delivered to tissue by the jaws as they are moved to the closed or opened position. 
         [0006]    Instruments disclosed in the present application constitute improvements over conventional flexible instruments due to their torsional rigidity, their ability to operatively couple to actuation devices of the type described in the co-pending application, and their ability to deliver adequate forces at the jaws (e.g. dissection forces) when opened and closed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a perspective view of an embodiment of a forceps device; 
           [0008]      FIG. 2  is a perspective view of the distal end of the device of  FIG. 1  in which features of the shaft are partially exploded; 
           [0009]      FIG. 3  is a perspective view of the distal end of the shaft with the outer sheath removed; 
           [0010]      FIG. 4  is an exploded perspective view of the jaw tip; 
           [0011]      FIG. 5  is a perspective view of the jaw tip with the clevis exploded from the other components; 
           [0012]      FIG. 6A  is a partially exploded view of the proximal portion of the shaft of the device of  FIG. 1 ; 
           [0013]      FIG. 6B  is a cross-section view of the shaft taken along the plane designed  6 B- 6 B in  FIG. 1 ; 
           [0014]      FIG. 7  is a longitudinal cross-section view of the proximal portion of the shaft and the handle. 
           [0015]      FIG. 8  is a perspective view of an embodiment of a second embodiment in the form of a grasping forceps device; 
           [0016]      FIG. 9  is a perspective view of the distal end of the device of  FIG. 8  in which features of the shaft are partially exploded; 
           [0017]      FIG. 10  is similar to  FIG. 9 , but shows only the clevis exploded from the other components. The outer tube is not shown in  FIG. 10 ; 
           [0018]      FIG. 11A  is a partially exploded view of the proximal portion of the shaft of the device of  FIG. 8 ; 
           [0019]      FIG. 11B  is a cross-section view of the shaft taken along the plane designed  11 B- 114 B in  FIG. 8 ; 
           [0020]      FIG. 12  is a longitudinal cross-section view of the proximal portion of the shaft and the handle. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]      FIG. 1  shows an embodiment of a medical instrument  100 . The instrument  100  includes an elongate shaft  10  having a Maryland dissector jaw tip  12  at its distal end. A handle  14  is mounted to the proximal end of the elongate shaft  10 . 
         [0022]    Referring to  FIG. 2 , the elongate shaft  10  includes an elongate coil  18  extending distally from the handle  14 . The coil is preferably formed of a stainless steel ribbon having a rectangular cross-section. A clevis  20  having a tubular collar  22  is positioned at the distal end of the shaft  10 . The tubular collar  22  of the clevis is disposed over and fixedly attached to the distal end of the coil tube  18  (also see  FIG. 3 ) such as by welding or other methods. A composite flexible outer sleeve  16  is positioned over the tubular collar  22  and the coil tube  18  and extends to the proximal end of the shaft  10 . The outer sleeve  16  is a torque transmissible sleeve formed of a polymeric inner layer (e.g. PTFE), a polymeric outer layer (e.g. Pebax), and a braid between the inner and outer layers. The braid is preferably a kink-resistant stainless steel flat wire braid woven in a diamond pattern, although other patterns might alternatively be used. The outer sleeve  16  is fixed to the tubular collar  22  of the clevis by bonding or other suitable methods. 
         [0023]    The actuation cable  24  extends from the lumen of the coil  18  into the clevis  20 . Referring to  FIG. 4 , the actuation cable  24  includes an actuation tip  26  having a head  27  pivotally coupled to upper and lower jaw links  28   a,    28   b  by proximal pins  30 . Distal pins  32  couple jaw members  34   a,    34   b  of the jaw tip  12  to the links  28   a,    28   b.  The jaw members  34   a,    34   b  are pivotable about a common clevis pin  36  that extends through holes  38  in the clevis  20 . With the illustrated arrangement of jaw links and jaw members, movement of the actuation cable  24  in a proximal direction moves the jaws from a closed position to the open position shown in the drawings. Movement of the actuation cable  24  in a distal direction closes the jaws. The jaws may be biased in the opened or closed position, or they may be unbiased. 
         [0024]    Referring to  FIGS. 6A and 6B , a rigid tube  40  is disposed around a proximal portion of the outer tube  16  proximal to the handle  14  and is attached to the outer tube by bonding or other methods. An end plate such as a washer  43  ( FIG. 4A ) is attached at the proximal end of the instrument tube  40 . The coil tube  18  is fixedly attached to the instrument tube  40  at the end plate  43 . As shown in  FIG. 7 , the handle includes a pair of grips  42   a,    42   b  pivotally coupled to one another. A knob  44  rotatably positioned on a distal portion of the handle  14  (e.g. at grip  42   a ) is fixed to the rigid tube  40  such that rotation of the knob results in axial rotation of the rigid tube, outer tube  16  and coil. The rigid tube  40 , the outer tube  16 , and the inner coil (not shown in  FIG. 7 ) comprising the proximal portion of the shaft  10  extend proximally from the knob  44  into a bore  46  in the grip  42   a  of handle  14 . The shaft  10  is rotatable within the bore  46  when it is axially rotated by the knob  44 . 
         [0025]    As best shown in  FIG. 6B , the actuation cable  24  extends proximally into the lumen of a rigid actuation tube  25  disposed within the rigid tube  40 . The actuation cable  24  is welded, soldered, or otherwise fixed rigid tube. The actuation tube  25  extends out of the rigid tube  40  through washer  43  as most easily seen in  FIG. 7 , and is disposed within an opening  48  in the grip  42   b.  An element  50  (e.g. the bead  50  shown in  FIG. 6B ) at the proximal end of the actuation tube  25  is captured within the opening  48  in a manner that permits the cable to axially rotate with the shaft  10  is rotated. In the drawings, the element  50  is captured within a pivot  52  in the grip  42   b.    
         [0026]    To close the jaws, the user squeezes the grips  42   a,    42   b,  causing the lower portion of grip  42   b  to pivot towards grip  42   a.  The upper portion of the  42   b  pivots proximally, pushing the actuation tube  25  and cable  24  distally. Because the proximal and distal ends of the coil  18  are fixed to the outer tube  16 , the ability of the coil  18  to stretch when the actuation tube/cable  25 / 24  are pushed is limited by the ability of the outer tube  16  to stretch. Thus, the outer tube  16  is constructed to be significantly more stretch resistant than the coil. The material forming the outer tube  16  is selected to give the outer tube a durometer that will resist stretching sufficiently allow the jaws to close with the closing forces adequate for the procedure. For any given coil, a higher durometer shaft will allow higher closing forces to be achieved at the jaws, whereas a lower durometer shaft will stretch more readily and will thus limit the closing forces that can be achieved at the jaws. 
         [0027]    To open the jaws, the grip  42   b  is pivoted forward to pull the actuation tube  25  and cable  24  proximally, thereby spreading the jaws to the opened position. 
         [0028]    To change the axial orientation of the jaws, the user rotates the knob  44 , causing the rigid tube  40 , inner coil  18 , outer tube  16  and actuation cable/tube  24 / 25  to rotate axially. The braid of the outer tube as well as the rigid coupling of the coil to both the clevis and the rigid tube provide torqueability with a substantially one to one ratio of movement between the handle and the jaw tip regardless of the direction in which the instrument is being axially rotated. 
         [0029]    It should be appreciated that the principles of the invention may be applied to other forms of devices that utilize jaws, such as graspers, scissors, clip appliers and forceps, as wells as instruments such as electrocautery hooks that do not have jaws.  FIG. 8  shows an alternative embodiment of a medical instrument  200  in the form of a blunt nose grasper. 
         [0030]    The instrument  200  includes an elongate shaft  10  having a jaw tip  112  at its distal end. A handle  114  is mounted to the proximal end of the elongate shaft  110 . 
         [0031]    Referring to  FIG. 9 , the elongate shaft  10  includes an elongate coil  18  extending distally from the handle  14 . The coil is preferably formed of a stainless steel ribbon having a rectangular cross-section. A clevis  120  having a tubular collar  122  is positioned at the distal end of the shaft  110 . The tubular collar  122  of the clevis is fixedly attached to the distal end of the coil tube  118  such as by welding or other methods. A composite flexible outer sleeve  116  is positioned over the tubular collar  122  and the coil tube  18  and extends to the proximal end of the shaft  110 . The outer sleeve  116  is a torque transmissible sleeve formed of a polymeric inner layer (e.g. PTFE), a polymeric outer layer (e.g. Pebax), and a braid between the inner and outer layers. The braid is preferably a kink-resistant stainless steel flat wire braid woven in a diamond pattern, although other patterns might alternatively be used. The outer sleeve  16  is fixed to the tubular collar  122  of the clevis by bonding or other suitable methods. 
         [0032]    The actuation cable  124  extends from the lumen of the coil  118  into the clevis  120 . Referring to  FIG. 10 , the actuation cable  24  includes an actuation tip  126  having a head  127  pivotally coupled to upper and lower jaw links  128   a,    128   b  by proximal pins  130 . Distal pins  132  couple jaw members  134   a,    134   b  of the jaw tip  112  to the links  128   a,    128   b.  The jaw members  134   a,    134   b  are pivotable about a common clevis pin  136  that extends through holes  138  in the clevis  120 . With the illustrated arrangement of jaw links and jaw members, movement of the actuation cable  124  in a proximal direction moves the jaws from an opened position to the closed position shown in  FIG. 9 . Movement of the actuation cable  124  in a distal direction opens the jaws. The jaws may be biased in the opened or closed position, or they may be unbiased, depending on the application for the instrument. 
         [0033]    Referring to  FIGS. 11A and 11B , a rigid tube  140  is disposed around a proximal portion of the outer tube  116  proximal to the handle  114  and is attached to the outer tube by bonding or other methods. An end plate such as a washer  143  ( FIG. 11A ) is attached at the proximal end of the instrument tube  140 . The coil tube  118  is fixedly attached to the instrument tube  140  at the end plate  143 . As shown in  FIG. 12 , the handle includes a pair of grips  142   a,    142   b  pivotally coupled to one another. A knob  144  rotatably positioned on a distal portion of the handle  114  (e.g. at grip  142   a ) is fixed to the rigid tube  140  such that rotation of the knob results in axial rotation of the rigid tube, outer tube  116  and coil. The rigid tube  40 , the outer tube  116 , and the inner coil (not shown in  FIG. 12 ) comprising the proximal portion of the shaft  110  extend proximally from the knob  144  into a bore  146  in the grip  142   a  of handle  114 . The shaft  110  is rotatable within the bore  146  when it is axially rotated by the knob  144 . 
         [0034]    As best shown in  FIG. 11B , the actuation cable  124  extends proximally into the lumen of a rigid actuation tube  125  disposed within the rigid tube  140 . The actuation cable  124  is welded, soldered, or otherwise fixed rigid tube. The actuation tube  125  extends out of the rigid tube  140  through washer  143  as most easily seen in  FIG. 12 , and is disposed within an opening  148  in the grip  142   b.  An element  150  (e.g. the bead  150  shown in  FIG. 11B ) at the proximal end of the actuation tube  125  is captured within the opening  148  in a manner that permits the cable to axially rotate with the shaft  110  is rotated. In the drawings, the element  150  is captured within a pivot  152  in the grip  142   b.    
         [0035]    To close the jaws, the user squeezes the grips  142   a,    142   b,  causing the lower portion of grip  142   b  to pivot towards grip  142   a.  The upper portion of the  142   b  pivots proximally, pulling the actuation cable  124  proximally. To change the axial orientation of the jaws, the user rotates the knob  144 , causing the rigid tube  140 , inner coil  118 , outer tube  116  and actuation cable/tube  124 / 125  to rotate axially. The braid of the outer tube as well as the rigid coupling of the coil to both the clevis and the rigid tube provide torqueability with a substantially one to one ratio of movement between the handle and the jaw tip regardless of the direction in which the instrument is being axially rotated. 
         [0036]    While certain embodiments have been described above, it should be understood that these embodiments are presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. This is especially true in light of technology and terms within the relevant art(s) that may be later developed. 
         [0037]    Any and all patents, patent applications and printed publications referred to above are incorporated by reference.