Abstract:
A surgical instrument can comprise an elongate tube including a camming rod and an actuation mechanism operably connected to the camming rod; a first jaw spine having a first cam slot; and a second jaw spine having a second cam slot, the second jaw spine pivotally connected to the first jaw spine at a common pivot pin connected to the elongate tube. A camming pin rides along first and second interior camming surfaces and closes the jaw spines when the camming rod moves proximally. When the camming rod moves distally, a camming projection rides on first and second exterior camming surfaces on proximal sides of the first and second jaw spines and opens the jaw spines. One camming surface on each jaw spine facilitates closing the jaw spines while the other camming surface on each jaw spine facilitates opening the jaw spines. These two camming surfaces can be widely separated.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/359,836, entitled “OVERMOLDED GRASPER JAW,” filed on Jan. 26, 2009, currently pending, which is a continuation of U.S. patent application Ser. No. 10/986,993, entitled “OVERMOLDED GRASPER JAW,” filed on Nov. 12, 2004, now U.S. Pat. No. 7,494,501, which is a non-provisional application claiming the priority of provisional application Ser. No. 60/519,849, filed on Nov. 12, 2003, entitled “OVERMOLDED GRASPER JAW AND DOUBLE CAMMING ACTUATION MECHANISM.” The entireties of all of these applications are fully incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention generally relates to surgical graspers having opposing jaws and, in particular, to composite grasper jaws and mechanisms for actuating the jaws. 
         [0004]    2. Discussion of Related Art 
         [0005]    In the past, grasper jaws have been formed of metal in order to provide strength and reliability. Various processes of forming the metal have included stamping, EDM (Electrical Discharge Machining), photochemical etching, water jet cutting, laser cutting, and machining. All of these processes are relatively expensive and time consuming since the jaws must end up with outer surfaces and edges which are atraumatic to body tissue. In addition, the actuation mechanisms of the past have typically operated with a single pin moveable axially within two slots, each associated with one of the jaws. The two slots have provided four camming surfaces to open and close each of the two jaws. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is directed to a surgical instrument such as a surgical grasper comprising an elongate tube extending along an axis including a camming rod and an actuation mechanism operably connected to the camming rod, the camming rod having a camming pin and a camming projection; a first jaw spine having a first cam slot, a first interior camming surface, and a first exterior camming surface; and a second jaw spine having a second cam slot, a second interior camming surface, and a second exterior camming surface, the second jaw spine pivotally connected to the first jaw spine at a common pivot pin operably connected to the elongate tube to open and close the jaw spines in response to movement of the actuation mechanism. 
         [0007]    A feature of the invention is the camming pin rides along the first and second interior camming surfaces and operates to close the jaw spines when the camming rod is moved proximally. With this aspect, the first exterior camming surface is formed on the proximal side of the first jaw spine, the second exterior camming surface is formed on the proximal side of the second jaw spine, and when the camming rod moves distally, the camming projection rides on the first and second exterior camming surfaces and operates to open the respective first and second jaw spines. In other words, one camming surface on each jaw spine can facilitate closing the jaw spines while the other camming surface on each jaw spine can facilitate opening the jaw spines. These two camming surfaces on each jaw spine can be widely separated to provide different mechanical advantages for the opening and closing operations. With this aspect, the closing camming surfaces can be positioned further from the common pivot point to provide an increase mechanical advantage for opening the jaw spines. This is particularly beneficial during a surgical procedure involving the blunt dissection of tissue. The different mechanical advantages also can be tailored to accommodate the different loads encountered when closing and opening the jaw spines. 
         [0008]    The jaw spines can be formed of a metallic material and are overmolded with an atraumatic plastic material. The combination of the metal spine and plastic overmold provide a very rigid composite jaw while accommodating relatively inexpensive manufacturing technologies. For example, the jaw spines do not need to be manufactured with a process demanding an atraumatic outer surface. By overmolding the plastic onto the metal spine, an atraumatic outer surface can be formed of the plastic material along with a high degree of detail. Additionally, the overmolded jaws can be provided with features that facilitate application of atraumatic pads. 
         [0009]    In another aspect, the invention is directed to a surgical instrument comprising an elongate tube extending along an axis including an actuation rod; a first jaw spine having a proximal end; a second jaw spine having a proximal end, the second jaw spine being pivotally connected to the first jaw spine at a common pivot pin operably connected to the elongate tube to open and close the jaw spines in response to movement of the actuation rod; a first link having a distal end pivotally connected to the proximal end of the second jaw spine and a proximal end pivotally connected to a pivot pin on the actuation rod; and a second link having a distal end pivotally connected to the proximal end of the first jaw spine and a proximal end pivotally connected to the pivot pin of the actuation rod. 
         [0010]    In another aspect, the surgical instrument of the invention comprises an elongate tube extending along an axis including an actuation rod; a first jaw spine having a proximal end and a distal end, the proximal end having a first series of gear teeth formed around a first hole; a second jaw spine having a proximal end and a distal end, the proximal end having a second series of gear teeth formed around a second hole, the second jaw spine being pivotally joined to the first jaw spine by a pivot pin through the first and second holes that operably opens and closes the jaw spines in response to movement of the actuation rod; and the elongate tube having a first fenestration of windows extending axially on one side of the tube and a second fenestration of windows extending on an opposite side of the tube facing the first fenestration of windows such that the first series of gear teeth can be positioned to ride within the first fenestration of windows and the second series of gear teeth can be positioned to ride within the second fenestration of window. With this aspect, when the actuation rod is drawn proximally within the elongate tube, the first and second series of gear teeth are pivoted on the pivot pin by the respective first and second fenestration of windows; and when the actuation rod is moved distally relative to the elongate tube, the first and second fenestrations of windows rotate the respective first and second series of gear teeth in opposite directions to an open position. 
         [0011]    In yet another aspect, the invention is directed to a surgical instrument comprising an elongate tube extending along an axis including an actuation rod; a first jaw spine having a first cam slot, the first jaw spine being coupled to the elongate tube by a first pivot pin; and a second jaw spine having a second cam slot, the second jaw spine being coupled to the elongate tube by a second pivot pin, the second jaw spine being connected to the first jaw spine at a common pin attached to the actuation rod that rides within the first and second cam slots associated with the respective first and second jaw spines. When the actuation rod is moved distally, the common pin rides within the first and second cam slots causing the respective first and second jaw spines to rotate on the respective first and second pivot pins to an open position. When the actuation rod is pulled proximally relative to the elongate tube, the common pin moves to the proximal ends of the first and second cam slots causing the jaw spines to pivot on their respective first and second pivot pins to a generally closed position. 
         [0012]    In another aspect, the invention is directed to a surgical instrument comprising an elongate tube extending along an axis including an outer tube and an actuation rod; a first jaw spine having a first cam slot, the first jaw spine being coupled to the outer tube by a first pivot pin disposed in the first cam slot; and a second jaw spine having a second cam slot, the second jaw spine being coupled to the outer tube by a second pivot pin disposed in the second cam slot, the second jaw spine being pivotally connected to the first jaw spine at a common pin attached to the actuation rod. When the actuation rod is moved distally relative to the outer tube, the first and second jaw spines pivot on the common pin as the respective first and second pivot pins ride within the respective first and second cam slots causing the first and second jaw spines to open. 
         [0013]    In yet another aspect, the invention is directed to a surgical instrument comprising an elongate tube extending along an axis including an outer tube and an actuation rod; a first jaw spine having a first outer surface and a first stub extending outwardly of the first outer surface; and a second jaw spine having a second outer surface and a second stub extending outwardly of the second surface, the second jaw spine being pivotally connected to the first jaw spine by a common pin attached to the outer tube, wherein the actuation rod is bifurcated at its distal end to form two extensions that extend outwardly of the first and second surfaces, respectively. Each of the two extensions further comprises a slot, and the slots traverse one another and to the axis. Each of the slots of the two extensions is sized and configured to receive their respective first and second stubs associated with the respective first and second jaw spines. When the actuation rod is moved distally relative to the outer tube, the first and second stubs are forced to the distal end of their respective first and second slots causing the respective first and second jaw spines to close. When the actuation rod is pulled proximally relative to the outer tube, the first and second stubs are moved inwardly as they transition to the distal end of the respective first and second slots causing the respective first and second jaw spines to move to an open position. 
         [0014]    These and other features and advantages of the invention will become more apparent with the description of the invention and reference to the associated drawings. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0015]    The accompanying drawings, which are included in and constitute a part of this specification, illustrate the embodiments of the invention and, together with the description, explain the features, advantages and principles of the invention. In the drawings: 
           [0016]      FIG. 1  is a top plan view of a grasper of the invention including a single pivot pin and a double cam mechanism; 
           [0017]      FIG. 2  is a bottom plan view of the grasper jaw of  FIG. 1  illustrating in greater detail four camming surfaces associated with the jaws; 
           [0018]      FIG. 3  is a perspective view of a grasper jaw in accordance with another embodiment of the invention including linkage in an actuation mechanism; 
           [0019]      FIG. 4  is a perspective view of an actuation mechanism of a grasper jaw in accordance with another embodiment of the invention including a rack and pinion; 
           [0020]      FIG. 5  is a perspective view of the actuation mechanism shown in  FIG. 4  in an open position; 
           [0021]      FIG. 6  is a top perspective view of the top jaw of the grasper jaw of  FIG. 4 ; 
           [0022]      FIG. 7  is a bottom perspective view of the bottom jaw of the grasper jaw of  FIG. 4 ; 
           [0023]      FIG. 8  is a side elevation view of an actuation mechanism of a grasper jaw in accordance with another embodiment of the invention including a separate pivot for each of the jaws; 
           [0024]      FIG. 9  is a top plan view of an actuation mechanism of a grasper jaw in accordance with another embodiment of the invention having a double pivot and slotted jaws; 
           [0025]      FIG. 10  is a bottom plan view of the grasper jaw of  FIG. 9 ; 
           [0026]      FIG. 11  is a top plan view of an actuation mechanism of a grasper jaw in accordance with another embodiment of the invention including a double pivot and a double cam; 
           [0027]      FIG. 12  is a bottom plan view of the grasper jaw of  FIG. 11 ; 
           [0028]      FIG. 13  is a top plan view of an actuation mechanism of a grasper jaw in accordance with another embodiment of the invention having a reversed slot with a pivot; 
           [0029]      FIG. 14  is a bottom plan view of the grasper jaw of  FIG. 13 ; 
           [0030]      FIG. 15  is a top plan view of an actuation mechanism of a grasper jaw in accordance with another embodiment of the invention having a slotted actuation rod; and 
           [0031]      FIG. 16  is a bottom plan view of the grasper jaw of  FIG. 15 . 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0032]    A surgical grasper is illustrated in  FIG. 1  and designated by the reference numeral  10 . The grasper is an elongate device having an axis  12  which extends between a proximal end  14  and a distal end  16 . A pair of opposing jaw spines  18  and  21 , disposed at the distal end  16 , are operable between opened and closed positions by an actuation mechanism  23 . A shaft assembly  25  extends along the axis  12  and includes an outer tube  27  and an inner actuation rod  30 . The spines  18  and  21  are pivotally attached to the outer tube  27  by a common pivot pin  32 . 
         [0033]    The actuation mechanism  23  includes a distal camming pin  34  and a proximal camming projection  36 . Both the pin  34  and projection  36  are carried by the actuation rod  30  which is moveable axially within the outer tube  27 . 
         [0034]    The camming pin  34  rides on two interior camming surfaces  38  and  41  each of which defines a slot in one of the jaw spines  21  and  18 , respectively. When the actuation rod  30  is moved proximally, the camming pin  34  rides along the camming surfaces  38  and  41  and operates to close the jaw spines  18  and  21 . 
         [0035]    The camming projection  36  operates with respect to exterior camming surfaces  43  and  45  that are formed on the proximal side of the jaw spines  21  and  18 , respectively. When the actuation rod  30  is moved distally, it rides on the exterior camming surfaces  43  and  45 , and operates to open the jaw spines  18  and  21 . 
         [0036]    Thus, this embodiment includes two pairs of camming surfaces, namely the surfaces  38  and  41  and the surfaces  43  and  45 , which can be disposed at different angles with respect to the axis  12 . In this manner, the opening and closing of the jaws can be accomplished with different mechanical advantages. This enables the actuation mechanism  23  to be structured so that there is a higher mechanical advantage for closing the jaws when an increased load is encountered, and a lower mechanical advantage for opening the jaws when a higher speed may be desired. 
         [0037]    In the embodiment of  FIG. 3 , elements of structure similar to those previously described are designated with the same reference numeral followed by the lower case letter “a.” It can be seen that this embodiment includes the shaft assembly  25   a , the outer tube  27   a  and the actuation rod  30   a , as well as the jaw spines  18   a  and  21   a  that are pivotally connected on the common pivot pin  32   a . However, in this embodiment the proximal ends of the jaw spines  18   a  and  21   a  are coupled to the actuation rod  30   a  by a pair of links  50  and  47 , respectively. These links  47  and  50  are pivotally connected through a common pivot pin  52  to the actuation rod  30   a . At their distal ends, the links  47  and  50  are individually connected to the jaw spines  21   a  and  18   a , respectively. Thus, the link  47  is coupled to the jaw spine  21   a  by a pivot pin  54  and the link  50  is coupled to the jaw spine  18   a  through a pivot pin  56 . 
         [0038]    In operation, the embodiment of  FIG. 3  also functions with the actuation rod  30   a  being moved axially relative to the outer tube  27   a . When the actuation rod  30   a  is moved distally, the pivot pin  52  approaches the pivot pin  32   a . This causes the distal ends of the links  47  and  50  to spread, resulting in the separation or opening of the jaw spines  18   a  and  21   a . When the actuation rod  30   a  is pulled proximally relative to the outer tube  27   a , the pin  52  moves away from the pin  32   a  causing the distal end of the links  47  and  50  to draw inwardly thereby closing the jaw spines  18   a  and  21   a.    
         [0039]    Referring to  FIG. 4 , elements of structure similar to those previously discussed will be designated with the same reference numeral followed by the lower case letter “b.” Thus, this embodiment includes the outer tube  27   b , actuation rod  30   b , as well as the jaw spines  18   b  and  21   b . In this case, the outer tube  27   b  is provided with a fenestration of windows  58  extending axially on one side of the outer tube  27   b . A similar fenestration of windows  61  extends axially on the opposite side of the outer tube  27   b.    
         [0040]    The jaw spines  18   b  and  21   b  are best illustrated in the perspective views of  FIGS. 6 and 7 . On the proximal end of the jaw spine  18   b , a series of gear teeth  63  are centered on a hole  65  that is offset from the longitudinal dimension of the jaw spine  18   b . The jaw spine  21   b  is similarly constructed with a plurality of gear teeth  67  centered on a hole  70  that is offset from the longitudinal dimension of the jaw spine  21   b.    
         [0041]    In operation, the jaw spines  18   b  and  21   b  are joined by the pivot pin  32   b  ( FIG. 5 ), which extends through the holes  65  and  70 . The pin  32   b  can be further extended into at least one axial slot  72  in the outer tube  27   b . This axial slot  72  is positioned between the fenestration of windows  58  and the fenestration of windows  61 . 
         [0042]    With this configuration, the gear teeth  63  of the jaw spine  18   b  can be positioned to ride within the fenestration of windows  58 . Similarly, the gear teeth  67  of the jaw spine  21   b  can be positioned to ride within the fenestration of windows  61 . 
         [0043]    As with the previous embodiments, the actuation rod  30   b  is movable axially relative to the outer tube  27   b . This movement is restricted in this embodiment by the length of the axial slot  72 . When the actuation rod  30   b  is drawn proximally within the outer tube  27   b , the gear teeth  58  and  67  are pivoted on the pin  32   b  by the fenestration of windows  58  and  61 , respectively. With the windows  58  and  61  disposed on opposite sides of the outer tube  27   b , the jaw spines  18   b  and  21   b  are moved in different directions, in this case to a closed position as illustrated in  FIG. 4 . 
         [0044]    When the actuation rod  30   b  is moved distally relative to the outer tube  27   b , the fenestration of windows  58  and  61  rotate the gear teeth  63  and  67 , respectively, in opposite directions, in this case, to an open position as illustrated in  FIG. 5 . 
         [0045]    Another embodiment of the invention is illustrated in the side elevation view of  FIG. 8  where elements of structure similar to those previously discussed are designated with the same reference numeral followed by the lower case letter “c.” Thus, in this embodiment the jaw spines are designated by the reference numeral  18   c  and  21   c , while the outer tube and actuation rod are designated with the reference numerals  27   c  and  30   c , respectively. As illustrated in  FIG. 8 , the jaw spine  18   c  is pivotally attached to the outer tube  27   c  by a pivot pin  72 . Similarly, the jaw spine  21   c  is pivotally attached to the outer tube  27   c  by a pivot pin  74 . The jaw spines  18   c  and  21   c  are also attached to the actuation rod  30   c  by a common pivot pin  76 . 
         [0046]    As in previous embodiments, the device is operated by moving the actuation rod axially relative to the outer tube  27   c . With the common pivot pin  76  disposed inwardly of the individual pins  72  and  74 , the actuation rod  30   c  can be pulled proximally relative to the outer tube  27   c  to close the jaw spines  18   c  and  27   c . These jaw spines rotate on their individual pins  72  and  74  to a closed position as illustrated in  FIG. 8 . If the actuation rod  30   c  is pushed distally relative to the outer tube  27   c , the jaw spines  18   c  and  27   c  rotate on their respective pivot pins  72  and  74  outwardly to an open position. 
         [0047]    The embodiment of  FIG. 9  contains elements of structure which are similar to those previously disclosed. In this case, these elements are designated with the same reference numeral followed by the lower case letter “d.” Thus, this embodiment includes the outer tube  27   d , the actuation rod  30   d  and the jaw spines  18   d  and  21   d . The jaw spines  18   d  and  21   d  are coupled to the outer tube  27   d  by individual pivot pins  78  and  81 , respectively. With this embodiment, a common pin  83  is provided that is attached to the actuation rod  30   d , which rides within a pair of intersecting slots  85  and  87  associated with the jaw spines  21   d  and  18   d , respectively. 
         [0048]    As in previous embodiments, this device is operated by moving the actuation rod  30   d  axially relative to the outer tube  27   d . When the actuation rod  30   d  is moved distally, the common pin  83  rides within the respective slots  85  and  87  of the jaws  21   d  and  18   d . This causes the jaw spines  18   d  and  21   d  to rotate on the individual pivot pins  78  and  81 , respectively, to an open position as illustrated in  FIG. 9 . When the actuation rod  30   d  is pulled proximally relative to the outer tube  27   d , the common pin  83  moves to the proximal ends of the slots  85  and  87 . This causes the jaw spines  21   d  and  18   d  to pivot on their respective pins  81  and  78  to a generally closed position. 
         [0049]    In each of the above embodiments of the invention, the jaw spines such as jaw spines  18   d  and  21   d  can be overmolded with plastic to form a composite structure. In the example shown in  FIG. 9 , one of the composite jaws can be formed with the metal interior jaw spine  18   d  and an outer plastic overmold  90 . A similar outer plastic overmold  92  can be formed on the metal jaw spine  21   d . As noted, the plastic overmolds  90  and  92  can be easily and inexpensively provided with features such as a coupling detent  94  which is adapted to receive an atraumatic jaw pad  96 . It is these features which can be easily and inexpensively molded into the plastic overmold  90  but which would be economically impossible to form on metal jaws. Thus the rigid composite jaw formed of the jaw spine  18   d  and overmold  90  is not only practical but also cost effective and accordingly facilitates the application of additional features such as the disposable atraumatic pads  96 . 
         [0050]    The embodiment of  FIG. 11  is similar to that of  FIG. 9  where elements of structure similar to those previously discussed are designated with the same reference numeral followed by the lower case letter “e.” Thus, this embodiment includes the outer tube  27   e , the actuation rod  30   e , as well as the jaw spines  18   e ,  21   e  and associated overmolds  90   e  and  92   e , respectively. 
         [0051]    This embodiment is similar to that of  FIG. 9  in that it includes the individual pins  78  and  81 , as well as the common pin  83 . In this embodiment, however, the common pin  83  is disposed to pivotally connect the jaw spines  18   e  and  21   e  with the actuation rod  30   e . In other words, the common pin  83  is not disposed in slots, but rather is disposed in holes associated with the jaw spines  18   e  and  21   e . By comparison, it will be noted that the individual pins  78  and  81  are not disposed in holes, as is the case with the embodiment of  FIG. 9 , but rather are disposed in associated slots. 
         [0052]    In operation, as the actuation rod  30   e  is moved distally relative to the outer tube  27   e , the jaw spines  18   e  and  21   e  pivot on the common pin  83   e  as the individual pins  78   e  and  81   e  ride within the respective slots  101  and  98 . This movement causes the jaws  18   e  and  21   e  to open. Closure of the jaws  18   e  and  21   e  is achieved by drawing the actuation rod  30   e  proximally relative to the outer tube  27   e.    
         [0053]    A further embodiment of the invention is illustrated in  FIG. 13  wherein elements of structure similar to those previously disclosed are designated with the same reference numerals followed by the lower case letter “f.” Thus, this embodiment includes the outer tube  27   f , actuation rod  30   f , jaw spines  18   f  and  21   f , overmolds  90   f  and  92   f , as well as the common pivot pin  83   f , and slots  98   f  and  101   f . In this case, however, the slots  98   f  and  101   f  intersect so that the individual pins  81   e  and  78   e  (not shown) in the embodiment of  FIG. 11  can be combined into a common pin  103  which is fixed to the outer tube  27   f . With this exception involving the intersecting slots  98   f  and  101   f  in combination with the common pin  103 , the embodiment of  FIG. 13  functions in the same manner as that of  FIG. 11 . 
         [0054]    The embodiment of  FIG. 15  contains elements of structure which are similar to those previously disclosed. Accordingly, they are designated with the same reference numerals followed by the lower case letter “g.” Thus, this embodiment includes the outer tube  27   g , the actuating rod  30   g , the jaw spines  18   g  and  21   g  together with the associated overmolds  90   g  and  92   g . In this embodiment, the jaw spine  18   g  has an outer surface  107  while the jaw spine  21   g  has an outer surface  110 . A stub  112  is fixed, typically by welding, to the jaw spine  18   g  and extends outwardly of the surface  107 . In a similar manner, a separate stub  114  can be fixed to the jaw spine  21   g  to extend outwardly from the surface  110 . The jaw spines  18   g  and  21   g  are overlapped in a scissors configuration and held in a pivotal relationship with the outer tube  27   g  by a common pin  105 . 
         [0055]    The actuation rod  30   g  is bifurcated at its distal end to form two extensions  116  and  118  that extend outwardly of the surfaces  107  and  110 , respectively. These extensions  116  and  118  are provided with slots  121  and  123 , respectively, which are transversed to the axis  12   g  and also transverse to each other. In this embodiment, the slot  121  associated with the extension  116  is sized and configured to receive the stub  112  associated with the jaw spine  18   g . Similarly, the slot  123  associated with the extension  118  is sized and configured to receive the stub  114  associated with the jaw spine  21   g.    
         [0056]    In operation, the jaw spines  18   g  and  21   g  pivot about the common pin  105  between an open position and a closed position. As the actuating rod  30   g  is moved distally relative to the outer tube  27   g , the stubs  112  and  114  are forced to the distal end of their respective slots  121  and  123 . This causes the jaw spines  18   g  and  21   g  to close as they move toward each other. When the actuating rod  30   g  is pulled proximally relative to the outer tube  27   g , the stubs  112  and  114  are moved inwardly as they transition to the distal end of the respective slots  121  and  123 . This causes the associated jaw spines  18   g  and  21   g  to move to an open position as they separate. When the actuating rod  30   g  is pushed distally relative to the outer tube  27   g , the stubs  112  and  114  are moved outwardly as they transition to the proximal end of the respective slots  121  and  123 . This causes the associated jaw spines  18   g  and  21   g  to move to a closed position as they come together. 
         [0057]    There are many other embodiments of the invention which are operable with an actuating rod movable relative to an outer tube. Among these embodiments will be those which function by moving one of the jaw spines, such as the spine  18 , with the actuating rod  30  and then moving the other of the jaw spines, such as the spine  21 , with the first spine, such as the spine  18 . Various configurations of common pins, individual pins, and slots can be used for these embodiments.