Abstract:
A surgical stapler includes a head in which a plurality of staples are stored. The head includes a facing surface. The stapler also includes an anvil having an anvil surface shaped and dimensioned for forming the staples upon actuation of the surgical stapler, the anvil including a facing surface opposed to the facing surface of the head for mating engagement therewith. The facing surface of the head is obliquely oriented relative to a longitudinal axis of the head creating an elliptical staple line when the head is brought into contact with anvil during actuation of the surgical stapler.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a surgical stapler for anastomosis. More particularly, the invention relates to an intraluminal surgical stapler providing for the creation of an elliptical profile during anastomosis. 
     2. Description of the Prior Art 
     Surgical staplers have long been known in the surgical art as a quick and efficient way of joining or repairing tissue. Stapling has become an acceptable alternative to suturing. In certain types of surgical procedures, the use of surgical staples has become the preferred method of joining tissue and specially configured surgical staplers have been developed for these applications. 
     Intraluminal, or circular, staplers, have been developed for use in surgical procedures known as anastomosis. An example of an intraluminal surgical stapler used in performing anastomosis is disclosed in U.S. Pat. No. 5,104,025, which is incorporated herein by reference. 
     Conventional intraluminal surgical staplers typically include an elongated shaft having a proximal actuating mechanism and a distal stapling mechanism mounted to the shaft. The distal stapling mechanism typically includes a fixed stapling cartridge containing a plurality of staples configured in a concentric circular array. A round cutting knife is concentrically mounted in the cartridge interior to the staples. The knife is moved in an axial, distal direction during operation. Extending axially from the center of the cartridge is a trocar shaft. The trocar shaft is movable axially, with respect to the cartridge. An anvil member is mounted to the trocar shaft. The anvil member has a conventional staple anvil surface mounted to it for forming the ends of the staples. The distance between the distal face of the staple cartridge and the staple anvil surface can be controlled by an adjustment mechanism mounted to the proximal end of the trocar shaft. The tissue contained between the staple cartridge and the staple anvil surface is simultaneously stapled and cut when the actuating mechanism is triggered by the surgeon. 
     As briefly discussed above, an anastomosis involves a surgical procedure wherein sections of intestine are joined together after a connecting section has been excised. The procedure requires joining the ends of two tubular sections together to form a continuous tubular pathway. Prior to the introduction of intraluminal surgical staplers, the surgical procedure was a laborious and time-consuming procedure. The surgeon had to precisely cut and align the ends of the intestine and maintain the alignment while joining the ends of the tubular sections with numerous suture stitches. The development of intraluminal surgical staplers has greatly simplified the anastomosis procedure and also decreased the time required to perform an anastomosis. 
     When performing an anastomosis using an intraluminal surgical stapler, the intestine is typically stapled using a conventional surgical stapler with double rows of staples being positioned on either side of the target section of intestine. After removing the specimen, the surgeon typically inserts the anvil of the intraluminal surgical stapler into the proximal end of the lumen, proximal of the staple line. This is done by inserting the anvil into an entry port cut into the proximal lumen by the surgeon. On occasion, the anvil can be placed transanally by placing the anvil on the distal end of the stapler and inserting the instrument through the rectum. The surgeon then ties the proximal end of the intestine to the anvil shaft using a suture or other conventional tying device. The surgeon then cuts excised tissue adjacent to the tie and the surgeon attaches the anvil to the trocar shaft of the intraluminal surgical stapler. Next the surgeon closes the gap between the anvil and cartridge, thereby engaging the proximal and distal ends of the intestine in the gap. The surgeon next actuates the intraluminal surgical stapler causing several rows of staples to be driven through both ends of the intestine thereby joining the ends and forming a tubular pathway. Simultaneously, as the staples are driven and formed, a concentric circular blade is driven through the intestine tissue, cutting the ends adjacent to the inner row of staples. The surgeon then withdraws the stapler from the intestine and the anastomosis is complete. 
     By creating the staple line of the newly formed lumen along a plane perpendicular to the longitudinal axis of the lumen, substantial stresses occur within the lumen. In particular, material passing through the lumen is confronted with all edges of the staple line simultaneously. This results in great stresses along the staple line. In addition, the strength of the staple line is limited by the diameter and, thus the circumference, of the lumen at the point of the staple line. 
     With this in mind, a need currently exists for a mechanism that optimizes the strength and functionality of a staple line created by an intraluminal surgical stapler. The present invention provides such an apparatus. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide an elliptical surgical stapler including a head in which a plurality of staples are stored. The head includes a facing surface. The surgical stapler also includes an anvil having an anvil surface shaped and dimensioned for forming the staples upon actuation of the surgical stapler, the anvil including a facing surface opposed to the facing surface of the head for mating engagement therewith. The facing surface of the head is obliquely oriented relative to the longitudinal axis of the head creating an elliptical staple line when the head is brought into contact with the anvil during actuation of the surgical stapler. 
     It is also an object of the present invention to provide a surgical stapler including a head in which a plurality of staples are stored. The head includes a facing surface. The surgical stapler also includes an anvil including an anvil surface shaped and dimensioned for forming the staples upon actuation of the surgical stapler, the anvil including a facing surface opposed to the facing surface of the head for mating engagement therewith. The facing surfaces of the anvil and head define an oblique mating plane on which the anvil and head create an elliptical staple line due to angled elliptical profiles of the anvil and the head. 
     Other objects and advantages of the present invention will become apparent from the following detailed description when viewed in conjunction with the accompanying drawings, which set forth certain embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a surgical stapler of the present invention. 
         FIG. 2  is a perspective view of the head and anvil portion of a surgical stapler of the present invention. 
         FIGS. 3 ,  4 ,  5  and  6  are side views of a closing and stapling operation of the present invention. 
         FIG. 7  is an exploded perspective view of an anvil, anvil shaft and trocar of the present invention. 
         FIG. 8  is a side view in partial cross-section of the anvil taken along lines  8 - 8  of  FIG. 2 . 
         FIG. 9  is a side view in partial cross-section of a closed anvil shaft seated upon a trocar tip as described in the present invention. 
         FIG. 10  is a cross-sectional top view of an anvil shaft taken along lines  10 - 10  of  FIG. 9 . 
         FIG. 11  is a partial cut away side view of a trocar sheathing mechanism contained in the head portion of the present invention. 
         FIG. 12  is a schematic of an alternate embodiment in accordance with the present invention. 
         FIGS. 13 and 14  are detail views of the head and anvil in accordance with a preferred embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The detailed embodiments of the present invention are disclosed herein. It should be understood, however, that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the details disclosed herein are not to be interpreted as limiting, but merely as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. 
     With reference to the various figures, an intraluminal surgical stapler  10  in accordance with the present invention is disclosed. The surgical stapler  10  is substantially similar in structure and operation to intraluminal anastomotic surgical staplers such as those disclosed in commonly owned U.S. Pat. Nos. 5,104,025 to Main et al., entitled “INTRALUMINAL ANASTOMOTIC SURGICAL STAPLER WITH DETACHED ANVIL”, and 5,309,927 to Welch, entitled “CIRCULAR STAPLER TISSUE RETENTION SPRING METHOD”, both of which are incorporated herein by reference. While a preferred stapler design is disclosed in accordance with a preferred embodiment, the concepts underlying the present invention could be applied to a variety of stapler designs without departing from the spirit of the present invention. For example, it is contemplated the present invention could equally be applied to a stapler employing a detachable or non-detachable anvil. As those skilled in the art will appreciate, the term intraluminal surgical stapler is meant to refer to a class of surgical staplers designed to apply staples in a ring about the entire circumference of a vessel or organ during an anastomosis. 
     In general, the surgical stapler  10  includes a head  12 , an anvil  14 , an adjusting screw  16  and a trigger  18 . The trigger  18  acts to operate the stapler  10  when the safety is released. When the trigger  18  is activated, a firing mechanism (not shown) operates within the shaft  22  so staples are expelled from the head  12 . These staples are clinched about anvil surfaces  24  positioned circumferentially about the anvil body  26 . Simultaneously, a knife  13  (shown in broken lines) held within the head  12  acts to cut tissue held within the circumference of the surgical stapler  10  between the anvil  14  and the head  12 . The stapler  10  is then pulled through the tissue leaving stapled tissue in its place. 
     As seen in  FIGS. 1 ,  2  and  7 , the surgical stapler  10  of the present invention is disclosed. More specifically, as seen in  FIGS. 1 and 2 , there is shown a trocar shaft  28  containing a trocar tip  30 . The trocar shaft  28  is integral to the head  12  and is capable of piercing tissue. The trocar shaft  28  is surrounded by a trocar sleeve  32  that reciprocates into and out of the head  12 . The trocar sleeve  32  is held on the head  12  by a spring  34  that creates its resiliency and allows reciprocation of the trocar sleeve  32  about the trocar shaft  28 . 
     As seen in  FIGS. 3 and 11 , the trocar shaft  28  is generally covered by the sleeve  32  so that purse-stringed tissue may be placed over the trocar sleeve  32 . Nonetheless, the trocar tip  30  is capable of puncturing through tissue when pressure is applied. This is especially useful when connecting purse-stringed tissue. In this way, the trocar sleeve  32 , with the trocar tip  30  exposed, is capable of being forced through a purse-stringed tissue so the purse-string is not broken. After the trocar sleeve  32  is forced through the tissue, the trocar sleeve  32  surrounds the trocar tip  30  so no further damage will be done and, yet, the lumen is adequately attached over the trocar sleeve  32 . 
     Corresponding to the trocar shaft  28 , trocar tip  30  and trocar sleeve  32 , there is the anvil  14 . As mentioned above, the anvil  14  includes anvil surfaces  24  positioned circumferentially around the anvil body  26 . The anvil surfaces  24  correspond to staples held circumferentially within the head  12 . As will be noticed in  FIG. 3 , the anvil  14  may be placed within a lumen of tissue, and then the tissue purse-stringed about the anvil shaft  36 . An alignment mechanism (see  FIG. 8 ) is contained within the anvil  14 . As shown in  FIG. 8 , serrations  38  are formed along the anvil body  26 . These serrations  38  correspond with indentations or recesses  52  contained on the trocar tip  30 . When the anvil  14  is placed over trocar shaft  28 , the serrations  38  find corresponding recesses  52  and, therefore, are able to align the anvil surfaces  24  with the staples placed circumferentially about the head  12 . 
     In accordance with first and second embodiments of the present invention, the respective elliptical, annular facing surfaces  40 ,  40 ′,  42 ,  42 ′ of the head  12 ,  12 ′ and anvil  14 ,  14 ′ are oriented at an oblique angle relative to the longitudinal axis of the lumen through which they are passing. In the case of a surgical stapler having a straight supporting shaft with a longitudinal axis (see  FIGS. 1 through 11 ), the facing surface  40 ,  42  of the head  12  and anvil  14  are oriented at an oblique angle relative to the longitudinal axis of the supporting trocar shaft  28 . By orienting the facing surfaces  40 ,  42  of the head  12  and anvil  14  in this way, the resulting cut edges of the tissue acted upon by the present surgical stapler  10  are actually elliptically oriented when viewed normal to the cutting plane. 
     Since an elliptical ring cut obliquely to the longitudinal axis of a lumen will have greater surface area than a circle cut perpendicular to the same lumen, the cut surfaces created in accordance with the present invention provide for greater surface area in the stapling of adjacent tissue. This results in stronger coupling of the adjacent sections of the lumen and reduced interferences as bodily fluids pass by the cut surfaces of the lumen. 
     With reference to  FIGS. 1 through 11 , and in accordance with a first embodiment of the present invention, respective distal and proximal ends of the head  12  and anvil  14  are formed with angled facing surfaces  40 ,  42  defining an oblique mating plane on which the anvil  14  and head  12  will meet. By employing the angled facing surfaces  40 ,  42  in this manner, an elliptical staple line is created due to the tilting elliptical profiles of the proximal end of the anvil  14  and the distal end of the head  12 . The arc of the ellipse is a function of the inverse cosine of the angle of the tilt, and those skilled in the art will appreciate that the ellipse may be enlarged and\or reduced by simply altering the angle at which the respective proximal and distal facing surfaces  40 ,  42  of the head  12  and anvil  14  lie. In other words, the more the tilt, the greater the area of the ellipse and, therefore, the greater the area of the lumen left by the device. 
     Those skilled in the art will certainly appreciate that the specific staples are not disclosed in accordance with the disclosure of present invention. However, it should be understood that it is preferred that the staples exit the head perpendicularly from the facing surface of the head so that they meet the anvil perpendicularly to its facing surface. This way the staples can remain symmetrically constructed while allowing variable opening of the mouth of the instrument and still meet the anvil when fired. Such a design will require that the trocar also exits the instrument (where the staples exit from the head) and meets the anvil perpendicularly from the angled cut surface (where the pockets of the anvil are formed). 
     With this in mind, and in accordance a preferred embodiment of the present invention as disclosed with reference to  FIGS. 13 and 14 , the mating surfaces of the anvil  114  and head  112  are stepped, or otherwise offset, to create the elliptical surface desired in accordance with the present invention. More particularly, the respective distal and proximal ends of the head  112  and anvil  114  are formed with angled facing surfaces  140 ,  142  defining an oblique mating plane on which the anvil  114  and head  112  will meet. The angled facing surfaces  140 ,  142  respectively include a stepped construction composed of a series of lands  143  and risers  145 . The lands  143  and risers  145  extend about the respective angled facing surfaces  140 ,  142  in a manner creating a facing surface which lies in a plane which is obliquely oriented relative to the longitudinal axis of the surgical stapler  110 . 
     The staples used in accordance with this embodiment exit the head  112  in a direction perpendicular to the land  143  with which it is associated and form against the land  143  of the anvil  114  aligned therewith. As a result, the use of a stepped configuration addresses the staple formation concerns mentioned above by providing staple actuation which is oriented perpendicular to the contact surface of the anvil  114  and exit surface of the head  112 . 
     As discussed above, by employing the angled facing surfaces  140 ,  142  in this manner, an elliptical staple line is created wherein the arc of the ellipse is a function of the inverse cosine of the angle of the tilt. The use of a stepped construction further enhances the ability of the head  112  and anvil  114  to reliably and consistently close based upon the proper alignment of the lands  143  and risers  145  making up the angled facing surfaces  140 ,  142 . 
     Although a stepped surface is disclosed above in accordance with a preferred embodiment of the present invention, those skilled in the art will appreciate other offset constructions achieving an elliptical configuration may be employed without departing from the spirit of the present invention. 
     Referring to  FIG. 12 , the elliptical shape offered in accordance with the present invention may also be provided by tilting the entire distal end of the stapler such that the head  12 ′ and anvil  14 ′ meet in a plane which is obliquely oriented relative to the longitudinal axis of the shaft of the stapler  10 ′. More particularly, the elliptical, annular facing surface  40 ′ at the distal end of the head  12 ′ is oriented obliquely to the longitudinal axis of the lumen through which it is passing and to the longitudinal axis of the head  12 ′ as a whole. The elliptical, annular facing surface  42 ′ at the proximal end of the anvil  14 ′ is oriented obliquely to the longitudinal axis of the lumen through which it is passing but is perpendicular to the longitudinal axis of the anvil  14 ′ itself. As such, the anvil  14 ′ is moved into contact with the head  12 ′ along a line substantially perpendicular to the plane in which the facing surface  42 ′ along the distal end of the head  12 ′ lies. 
     In operation as seen in  FIGS. 3 ,  4 ,  5  and  6 , the anvil  14  with two lumens attached to both the trocar shaft  28  and tubular anvil extension  36 , respectively, is ready for surgery. As seen in  FIG. 4 , the anvil  14  is placed onto the trocar shaft  28  such that the trocar tip  30  is exposed and fits within the anvil shaft  36 . The trocar sleeve  32  is pushed to an exposed position so it is telescoped within the head  12 . When the trocar is adequately seated within the anvil head  26 , locking clip  46 , which contains the wedge shape spring, is caused to open and then grip about the indentation  50 . Because the recesses  52  have aligned themselves with serrations  38  in the trocar shaft  28 , it is ensured that the anvil surfaces  24  are aligned with the staples contained in the head  12 . As better seen in  FIG. 7 , the serrations  38  have been aligned with the anvil surfaces  24  during manufacture through accurate placement of bosses  52  into holes  54  when connecting the anvil head  26  to the tubular anvil extension  36 . The instrument now appears as two proximate pieces of lumen, as in  FIG. 5 . The adjusting screw  16  then pulls the tissue closer to each other. 
     As seen in  FIG. 6 , the staples have been fired into the anvil surfaces  24  through the tissue. Once the staples are clinched, a knife  13  cuts tissue held within the circumference of the staples. Once this cutting occurs the stapler  10  is pulled in the direction of the head  12  and through the lumen so that a circumferentially closed lumen with an inner tubular opening is now created. 
     After removing the stapler  10 , the excess lumen held in the stapler  10  is disposed. The release  44  on anvil  14  is pressed, as seen in  FIGS. 2 and 10 . This causes the locked mechanism as seen in  FIG. 9  to open as alluded to in  FIG. 7 . The locking clip  46  now opens, allowing the user to slide the anvil shaft  36  from the stapler head  12 . The tissue is held within the anvil  14  and head  12  is then removed. 
     In this way there has been proper purse-stringing and puncture by the trocar shaft  28 , alignment between the recesses  52  and the serrations  38 , pull through of the anvil body  26 , the locking clip  46  about the indention, and proper stapling and cutting of the tissue. 
     While the preferred embodiments have been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention.