Abstract:
A surgical device for applying a plurality of surgical staples is provided. The device includes a staple fastening assembly attached to a surgical instrument. The staple fastening assembly includes a pair of cooperating jaws, a jaw operating mechanism, and a gap sensor. A staple magazine having a plurality of staples and an anvil member having a plurality of staple pockets are attached to the jaws. The staple magazine includes a staple crimping cam and a staple dimpling cam that are operatively coupled to the surgical instrument. The jaw operating mechanism is operatively connected to a drive assembly in the surgical instrument for moving the jaws for automatically setting a tissue gap between the cooperating jaws. The gap sensor cooperates with the jaw operating mechanism for controlling staple formation.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to surgical fastener apparatus. More particularly, the present disclosure relates to apparatus for forming variable height surgical fasteners to body tissue in surgical procedures. 
         [0003]    2. Background of Related Art 
         [0004]    Surgical devices wherein tissue is first grasped or clamped between opposing jaw structure and then joined by means of surgical fasteners are well known in the art. In some instruments, a knife is provided to cut the tissue which has been joined by the fasteners. The fasteners are typically in the form of surgical staples. 
         [0005]    Instruments for this purpose may include two elongated members which are respectively used to capture or clamp tissue. Typically, one of the members carries a cartridge which houses a plurality of staples arranged in at least two lateral rows while the other member includes an anvil which defines a surface for forming the staple legs as the fasteners are driven from the cartridge. Generally, the stapling operation is effected by a pusher which travels longitudinally through the cartridge carrying member, with the pusher acting upon the staples for sequentially ejecting them from the cartridge. A knife may travel with the pusher between the staple rows to longitudinally cut and/or open the stapled tissue between the rows of staples. 
         [0006]    A later stapler disclosed in U.S. Pat. No. 3,499,591 applies a double row of staples on each side of the incision. This is accomplished by providing a cartridge assembly in which a cam member moves through an elongate guide path between two sets of staggered staple carrying grooves. Staple drive members are located within the grooves and are positioned in such a manner so as to be contacted by the longitudinally moving cam to effect ejection of the staples. Other examples of staplers are disclosed in U.S. Pat. Nos. 4,429,695, 5,065,929, and 5,156,614. 
       SUMMARY 
       [0007]    The present disclosure is directed towards a staple fastening assembly for use with a surgical instrument to apply surgical staples. The staple fastening assembly includes cooperative first and second jaws, a jaw operating mechanism, and a staple driving assembly. One jaw is generally elongate and includes a staple magazine. The staple magazine may be fixedly attached or releasably attached to the jaw and includes a plurality of staples arranged in at least one row. A first tissue contacting surface is defined on one face of the staple magazine and includes a plurality of retention slots corresponding to the number of staples included in the staple magazine. It is contemplated that multiple rows of staples may be provided and arranged in columns. The retention slots may be longitudinally aligned or offset from one another. Each retention slot is configured and adapted for releasably receiving its respective staple. Each staple includes first and second substantially parallel legs connected by a backspan forming substantially right angles to each of the legs. 
         [0008]    The second jaw is generally elongate and movable throughout a plurality of positions between an open position and a closed position. An anvil member is disposed on the second jaw and includes a second tissue contacting surface. The second tissue contacting surface includes a plurality of staple pockets wherein the number and arrangement of staple pockets corresponds to the number and arrangement of retention slots in the staple magazine. The second tissue contacting surface is oriented such that it is in juxtaposition with the first tissue contacting surface and defines a tissue gap therebetween. 
         [0009]    Each staple pocket includes a pair of staple forming grooves for capturing the legs of each staple. The staple forming grooves are substantially symmetrical about an intermediate point and have opposing inclined surfaces. A substantially lemniscate channeling surface is formed about a perimeter of each staple pocket. Each staple forming groove urges one leg of each staple towards the other leg while maintaining lateral separation of the legs during and after staple formation. 
         [0010]    The jaw operating mechanism is disposed in a housing that is attached to a proximal portion of the staple fastening assembly. The jaw operating mechanism includes a cam rotatably mounted to the housing, a cable, and a spring that are cooperatively coupled to one another. An approximating mechanism in the surgical instrument is operatively coupled to the jaw operating mechanism to cause proximal motion of the spring. Proximal movement of the spring is coupled to the cam via the cable. In one embodiment, the cam has an eccentric outer surface for maintaining contact between at least a portion of the outer surface of the cam and an outer surface of the second jaw. The cam may include an anti-reverse assembly (i.e. self-locking) to permit counter-clockwise rotation of the cam while inhibiting clockwise rotation of the cam. Configured thusly, counter-clockwise rotation of the eccentric cam continuously urges the second jaw towards the first jaw during proximal movement of the spring. The dimensions of the cam and the cable, as well as the dimensions and material selected for the spring, contribute towards the tissue capturing characteristics of the jaw operating mechanism. It is desirable for the jaws to capture and hold tissue in position while minimizing trauma to the tissue. Advantageously, the combination of the cam, the cable, and the spring allows for automatic adjustment of the tissue gap to accommodate different thicknesses of tissue during stapling operations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0011]    Embodiments of the presently disclosed surgical instrument are described herein with reference to the drawings, wherein: 
           [0012]      FIG. 1  is a side cross-sectional view of a staple fastening assembly in accordance with an embodiment of the present disclosure in an open position; 
           [0013]      FIG. 2  is a side cross-sectional view of the staple fastening assembly of  FIG. 1  in an intermediate position; 
           [0014]      FIG. 3  is a side cross-sectional view of the staple fastening assembly of  FIG. 1  in a closed position; 
           [0015]      FIG. 4  is a top plan view of a staple magazine of the staple fastening assembly of  FIG. 1 ; 
           [0016]      FIG. 5  is an exploded perspective view of a staple driving assembly showing the relationship among the several components; 
           [0017]      FIG. 6  is a bottom plan view of an anvil member; 
           [0018]      FIG. 6A  is a top plan view of a staple pocket; 
           [0019]      FIG. 7A  is a side view of an unformed staple; 
           [0020]      FIG. 7B  is a side view of the staple of  FIG. 7A  formed to a first configuration in accordance with the present disclosure; 
           [0021]      FIG. 7C  is a side view of the staple of  FIG. 7A  formed to a second configuration in accordance with the present disclosure; 
           [0022]      FIG. 7D  is a side view of the staple of  FIG. 7A  formed to a third configuration in accordance with the present disclosure; 
           [0023]      FIG. 7E  is a side view of the staple of  FIG. 7A  formed to a fourth configuration in accordance with the present disclosure; 
           [0024]      FIG. 7F  is a plan view of the staple of  FIG. 7B  showing an overlap between first and second legs of the staple; 
           [0025]      FIG. 8A  is an enlarged side view of a staple pocket, an unformed staple, a staple sled, and a rod sled; 
           [0026]      FIG. 8B  is an enlarged side view of the components of  FIG. 8A  showing the staple formed into a first configuration; and 
           [0027]      FIG. 8C  is an enlarged side view of the components of  FIG. 8B  showing a backspan of the staple being dimpled by the dimpling rod. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    Embodiments of the presently disclosed surgical instrument will now be described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein, the term “distal” refers to that portion of the instrument, or component thereof which is further from the user while the term “proximal” refers to that portion of the instrument or component thereof which is closer to the user. 
         [0029]    An example of a surgical stapling apparatus is disclosed in U.S. Pat. No. 5,480,089 to Blewett, currently owned by and assigned to United States Surgical, a division of Tyco Healthcare, the contents of which are hereby incorporated by reference in their entirety. Referring to  FIG. 1 , a staple fastening assembly, shown generally as  100 , includes a fixed first jaw  104 , a moveable second jaw  140 , and a jaw operating mechanism  160 . In one embodiment, staple fastening assembly  100  is adapted for use in connection with endoscopic or laparoscopic stapling instruments as are known in the art. 
         [0030]    First jaw  104  includes a staple magazine  120  having a first tissue contacting surface  122 . A plurality of retention slots  124  is included in staple magazine  120  where they are arranged in rows  126  on first tissue contacting surface  122  (see  FIG. 4 ). Each row  126  generally extends along a longitudinal axis of first jaw  104 . First tissue contacting surface  122  is generally elongate. Each retention slot  124  is configured for receiving a staple  110  and a staple ejector assembly. The staple ejector assembly includes a staple ejector  132 , a dimpling rod  138  (see  FIG. 5 ), a staple sled  134 , and a rod sled  136 . It is contemplated that staple magazine  120  may be removably attached to first jaw  104 . In a configuration where staple magazine  120  is a removable structure, once its complement of staples  110  have been expended, it may be removed and a new staple magazine  120  is attached to first jaw  104 . Each staple magazine  120  includes a full complement of staples  110  and at least one staple driving assembly  130  (shown in  FIG. 5  and discussed in detail below). 
         [0031]    Staple magazine  120  includes a plurality of longitudinal channels  128  (see  FIGS. 3 and 4 ) that are adapted for slidably receiving staple sled  134  and rod sled  136 . The number of channels  128  corresponds to the number of rows  126  of staples  110  included in staple magazine  120 . In one embodiment, staple magazine  120  include at least two rows  126  of staples  110 , although the procedure being performed, characteristics of the tissue to be fastened, and other considerations are factors in determining the number of rows  126 , as well as the number of staples  110 , included in each staple magazine  120 . Each row  126  in the plurality of rows has an identical quantity of staples  110 . 
         [0032]    Referring now to FIGS.  5  and  8 A- 8 C, in conjunction with  FIGS. 1-3 , staple driving assembly  130  is shown and it includes a staple ejector  132 , staple sled  134 , rod sled  136 , and a dimpling rod  138 . Each staple sled  134  is operatively coupled to a drive mechanism (not shown) of the surgical stapling instrument using structures that are known in the art. An example of such an instrument that includes a drive mechanism and an actuation mechanism is disclosed in U.S. Pat. No. 6,669,073 to Milliman et al., currently owned by and assigned to United States Surgical, a division of Tyco Healthcare, the contents of which are hereby incorporated by reference in their entirety. In embodiments that include a plurality of rows  126 , staple sleds  134  are operatively coupled to the drive mechanism such that their longitudinal travel is synchronized for ejecting a column  127  of staples  110  (see  FIG. 4 ) substantially simultaneously during an actuation sequence. Operation of the drive mechanism results in proximal and distal movement of the respective cams in response to actuation of the actuation mechanism. 
         [0033]    Staple sled  134  is a generally elongate structure having a pair of inclined surfaces  135   a ,  135   b  oriented towards the distal end of staple magazine  120 . Inclined surfaces  135   a,    135   b  are laterally spaced apart to define a passage  135   c  therebetween. Passage  135   c  is substantially flat and dimensioned for slidably receiving rod sled  136 . Rod sled  136  is a generally inclined structure having a substantially similar incline to that of staple sled  134 . Further still, staple ejector  132  includes a pair of legs  132   a,    132   b  that are laterally spaced apart and angled at their distal ends for readily engaging inclined surfaces  135   a,    135   b.  A throughhole  132   c  is centrally disposed in body  132   d  of staple ejector  132  and is dimensioned for slidably receiving dimpling rod  138 . 
         [0034]    Upon actuation of the actuation mechanism, staple sled  134  is driven through staple magazine  120  in a generally distal direction by the drive mechanism. As it translates through staple magazine  120 , staple sled  134  sequentially engages each staple ejector  132 . Staple sled  134  and staple ejector  132  have engaging surfaces with complementary angles such that distal horizontal motion of staple sled  134  results in vertical motion of staple ejector  132  which, in turn, drives staple  110  in a generally vertical direction towards anvil member  142 . During distal movement of staple sled  134 , rod sled  136  remains stationary in a proximal region of the magazine. In instances where a staple height of less than about 2.5 mm is desirable, as determined by tissue gap  102 , the actuation mechanism actuates the drive mechanism and drives rod sled  136  distally as will be discussed in detail hereinafter. 
         [0035]    With reference to  FIGS. 2 and 3 , a gap sensor  106  is disposed in a proximal portion of staple fastening assembly  100 . Gap sensor  106  is a generally elongate structure having a throughhole  109  disposed near one end. Further still, gap sensor  106  is fixedly attached to second jaw  140  and slidably received in an opening  105 . A dimple window  103  is disposed near a proximal portion of first jaw  104  and is configured for slidably receiving a dimpling rod driver  107 . Dimpling rod driver  107  is operatively coupled to the actuation mechanism and engages staple dimpling cam  136  when dimple window  103  is aligned with dimpling rod driver  107 . Gap sensor  106  is configured and dimensioned such that dimpling window  103  is aligned with dimpling rod driver  107  only when tissue gap  102  indicates that a staple height of less than about 2.5 mm is desired. 
         [0036]    In an embodiment having a staple height of less than about 2.5 mm, staple sled  134  leads rod sled  136  ( FIG. 5 ) during their travel through staple magazine  120 . As staple sled  134  translates distally through staple magazine  120 , rod sled  136  follows it after a predetermined time delay. Rod sled  136  is guided along its path by passage  135   c  of staple sled  134 . Therefore, staple sled  134  ejects staple  110  and drives it against anvil member  142  to form a staple having a height of about 2.5 mm as discussed above. Once staple  110  has been driven into staple pocket  150 , and before staple sled  134  passes staple ejector  132  (i.e. the delay between the sleds), sled  136  engages dimpling rod  138 . As rod sled  136  translates distally with staple sled  134 , it contacts dimpling rod  138  causing vertical motion thereof to engage backspan  116 . Rod sled  136  drives dimpling rod  138  such that it forms a depression in the center of backspan  116  and further increasing the holding strength of the formed staple  110 . 
         [0037]    As shown in  FIG. 4 , staple magazine  120  may have a plurality of rows  126  where retention slots  124  in each row  126  may be longitudinally offset from retention slots  124  in an adjacent row  126 . Since retention slots  124  are longitudinally offset, staple crimping cams  134  are operatively arranged and synchronized to eject the first staple  110  from each row  126  and advancing sequentially towards a distal end of staple magazine  120  and sequentially ejecting staples  110  from each row  126 . 
         [0038]    As shown in  FIGS. 1-3 , second jaw  140  is spaced apart from first jaw  104  defining a tissue gap  102  therebetween. Second jaw  140  is moveable through a plurality of positions between an open position and a closed position. In one embodiment, first jaw  104  and second jaw  140  are substantially parallel to one another throughout the plurality of positions. During operation, discussed in detail below, of staple fastening assembly  100 , second jaw  140  is moved towards first jaw  104  by jaw operating mechanism  160  that maintains a substantially parallel relationship between jaws  104  and  140 . 
         [0039]    Referring to  FIG. 1 , jaw operating mechanism  160  is disposed in a housing  170  and includes a cam  162 , a cable  164 , and a spring  166 . Cam  162 , cable  164 , and spring  166  are operatively connected to one another. A proximal portion of second jaw  140  is disposed within housing  170  and secured thereto. In particular, spring  166  is operatively coupled to an approximating mechanism (not shown) of the stapling instrument by structures as are known in the art. The approximating mechanism causes spring  166  to move proximally. Since cable  164  is operatively connected to spring  166 , this proximal movement of spring  166  results in proximal movement of cable  164  and counter-clockwise rotation of cam  162 . 
         [0040]    At least a portion of cam  162  contacts an outer surface  146  of second jaw  140  and it is self-locking in the counter-clockwise direction of rotation. Cam  162  has a centrally disposed orifice  163  for rotatably attaching it to housing  170 . Although orifice  163  is substantially circular, cam  162  has a generally eccentric shape, particularly along an outside surface, such that counter-clockwise rotation of cam  162  causes at least a portion of cam  162  to maintain contact with outer surface  146  thereby urging second jaw  140  towards first jaw  104  during counter-clockwise rotation. After cam  162  has rotated a desired amount, it locks in position such that no clockwise rotation is possible (i.e. self-locking), but additional counter-clockwise rotation is possible. A release mechanism, as is known in the art, operatively couples jaw operating mechanism  160  to the surgical stapling instrument. After a complete actuation sequence, the release mechanism is actuated to unlock cam  162  and permit clockwise rotation of cam  162 . Thusly, second jaw  140  is urged away from first jaw  104  by a biasing mechanism as is known in the art to separate the jaws and allow removal of the surgical stapling instrument. 
         [0041]    In one embodiment, cam  162 , cable  164 , and spring  166  are selected such that tissue T is captured and maintained between jaws  104 ,  140  using a minimum amount of applied pressure. The advantageous combination of cam  162 , cable  164 , and spring  166  captures different thicknesses of tissue T (i.e. each tissue thickness corresponds to a particular tissue gap  102 ) while minimizing trauma to tissue T as jaws  104 ,  140  capture tissue T therebetween. 
         [0042]    Referring now to  FIG. 6 , an anvil member  142  is illustrated. Anvil member  142  is generally elongate and includes a plurality of staple pockets  150  (see  FIG. 6A ) disposed on an second tissue contacting surface  144  where the number and arrangement of staple pockets  150  correspond to the number and arrangement of retention slots  124  in first tissue contacting surface  122 . An example of a staple pocket is disclosed in U.S. Pat. No. 5,480,089 to Blewett. With reference now to  FIG. 6A , each staple pocket  150  has a first staple leg forming groove  152  and a second staple leg forming groove  154  for forming respective legs  112 ,  114  of staple  110  (see  FIG. 7A ). Each staple forming groove  152 ,  154  is dimensioned to accommodate legs  112 ,  114  respectively. 
         [0043]    Staple leg forming grooves  152  and  154  are symmetrical about an intermediate point  156 . A substantially lemniscate (figure-eight shaped curve) channeling surface  158  is also formed in second tissue contacting surface  144  around a perimeter of staple pocket  150 . Each channeling surface  158  forms an angle θ, with respect to a plane defined by second tissue contacting surface  144 , wherein 0°&lt;θ&lt;90°. Each staple forming groove  152 ,  154  has a different slope than that of adjacent channeling surface  158 . More particularly, each staple forming groove  152 ,  154  has a sloped end  152   a,    154   a  to direct a corresponding staple leg  112 ,  114  towards a backspan  116  of staple  110 . Sloped ends  152   a,    154   a  are longitudinally opposed to one another. 
         [0044]    During an actuation sequence, staple  110  is ejected from retention slot  124  and directed towards anvil member  142  thereby driving legs  112  and  114  through tissue T to enter staple forming grooves  152 ,  154  respectively. As staple  110  contacts staple pocket  150 , staple forming grooves  152 ,  154  direct legs  112 ,  114  towards each other while maintaining lateral separation of legs  112 ,  114  so that they overlap one another as shown in  FIG. 7F . In particular, with reference to  FIGS. 7B-7D , during formation of staple  110 , staple forming groove  152 , in cooperation with channeling surface  158 , directs leg  112  towards backspan  116  alongside and substantially parallel to an unformed portion of leg  114 . Similarly, staple forming groove  154 , in cooperation with channeling surface  158 , directs leg  114  towards backspan  116  alongside and substantially parallel to an unformed portion of leg  112 . The amount of parallel overlap between leg  112  and the unformed portion of leg  114  is a function of tissue gap  102 . Similarly, the amount of parallel overlap between leg  114  and the unformed portion of leg  112  is also a function of tissue gap  102  that is controlled by the thickness of tissue T and operation of jaw operating mechanism  160 . 
         [0045]    Thusly, a larger tissue gap  102  results in a larger staple  110  height (e.g. about 4.8 mm as shown in  FIG. 7B ) while a smaller tissue gap  102  yields a smaller staple  110  height (e.g. about 2.5 mm as shown in  FIG. 7D ). In one embodiment, the actuation mechanism, in cooperation with staple magazine  120  and anvil member  142 , forms staples  110  having a height of between about 4.8 mm (i.e. the open position of second jaw  140 ) and about 2.5 mm (i.e. the closed position of second jaw  140 ) as determined by the thickness of tissue T and tissue gap  102 . It is to be understood that staples  110  may be formed having any height that is in the range of about 4.8 mm and about 2.5 mm as determined by the thickness of tissue T (an example is illustrated in  FIG. 7C ). In instances where tissue T thickness indicates a need for a smaller staple  110  height (i.e. less than about 2.5 mm or the dimpling position as seen in  FIG. 7E ), the actuation mechanism of the stapling instrument operates a second drive member that is operatively coupled to rod sled  136 , as discussed hereinabove. 
         [0046]    It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. For example, the staple forming structure disclosed herein can be adapted and configured for use in EEA, TA, and endoscopic staplers with similar effect. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.