Patent Publication Number: US-8109427-B2

Title: End-to end anastomosis instrument and method for performing same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 12/791,181 filed Jun. 1, 2010, now U.S. Pat. No. 7,931,183 which claims the benefit of and priority to U.S. application Ser. No. 11/429,505, filed on, May 5, 2006, now U.S. Pat. No. 7,743,598, which claims the benefit of and priority to U.S. application Ser. No. 11/415,737, filed on May 1, 2006, now U.S. Pat. No. 7,195,142, which claims the benefit of and priority to U.S. application Ser. No. 10/993,544, filed on Nov. 19, 2004 now U.S. Pat. No. 7,059,510, which claims the benefit of priority to PCT Application Ser. No. PCT/US03/18295, filed May 30, 2003, which claims the benefit of and priority to U.S. Ser. No. 10/160,460, filed on May 31, 2002, now U.S. Pat. No. 6,769,594, the entire contents of each of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The present disclosure relates to a surgical instrument and method for performing anastomosis of tubular body structures, and more particularly to an instrument for joining tubular tissues, for example, during gastrointestinal procedures. 
     Surgical stapling devices for applying an annular array of staples or fasteners to tissue are well known in the art. For example, surgical stapling devices for applying an annular array of staples, as well as devices for completing a surgical anastomosis through the provision of anastomosis rings, are well known in gastric and esophageal surgery, for example in classic or modified gastric reconstruction typically formed in an end to end, end to side, or side to side manner. 
     These devices generally include a circular array of fasteners such as staples, anastomosis rings, and the like, while the anvil member includes means for completing the circular anastomosis, typically an array of bucket members that cinch the staples after the staples are expelled from the fastener assembly, or may include a locking member for the anastomosis ring. 
     In use, the anvil is positioned within the lumen of an organ such as the stomach, esophagus, or intestine and the tissue is pulled about and around the anvil member and tied off, e.g., by a purse string suture, ring mechanism or the like. The fastener assembly is then positioned within the opposite end of the lumen and the tissue is pulled about and around the fastener assembly over the staple array and also tied off. At this point the tissue is positioned between the anvil and the fastener assembly. The anvil is typically slowly retracted (or advanced) to approximate the two tissue halves prior to deformation of the staples usually by virtue of a wing-nut and worm gear assembly which allows a surgeon to methodically advance the anvil towards the staple array to hold the tissue between the anvil and the fastener assembly. Many prior art devices also provide a visual indicator to signal the surgeon when the anvil has reached a firing position adjacent the staple or fastener assembly. 
     The surgeon then unlocks a safety device deform the staples against the anvil. As the staples or the fasteners are expelled from the fastener assembly, a circular knife typically follows the application of the staples to excise unwanted tissue at the anastomosis site. The instrument is then removed from the lumen of the organ. 
     The closing mechanisms associated with the prior art stapling or fastening devices typically utilize a complex worm gear arrangement or screw bearing member to approximate the spacing between the anvil and the fastener assembly. As mentioned above, this requires additional manipulation of the instrument by the surgeon during the surgery, e.g., the surgeon must grasp the device with one hand while rotating the knob or wing-like assembly with the other hand. As can be appreciated, moving the anvil member the full distance towards the fastener assembly can be a time consuming process during the surgical procedure. For example, many of the known prior art devices require 15 to 20 full 360° rotations of the knob or wing nut assembly to fully close the instrument in order to fire or expel the staples or fasteners into the tissue. 
     As can be appreciated, it would be advantageous to eliminate many of the above steps for performing the circular anastomosis of these tissue structures to expedite the overall surgical procedure. It would also be extremely advantageous to simplify the overall anastomosis procedure and reduce the level of manual intervention by the surgeon with respect to tying off the tubular ends prior to staple deformation. Moreover, it would be advantageous to provide an instrument which can perform end-to-end anastomosis deep within a tubular structure, e.g., colon, where known prior art devices cannot reach and the surgeon is forced to perform an gastrotomy and then make an incision within the side of the tubular structure to utilize these prior art devices. 
     A need also exists to develop a device which can be useful for low anterior resection of the colon which has proven difficult with a number of prior art devices. In addition, it would be useful to provide a device where the eversion of the tissue is exterior to the colon which facilitates future repair if needed and reduces the chances of stenosis at the anastomosis site. It would also be helpful to provide an instrument which reduces the amount of healthy tissue removed from the site during the anastomosis. 
     SUMMARY 
     The present disclosure relates to a surgical instrument for performing an end-to-end anastomosis of first and second luminal structures, such as two portions of the small intestine during a gastrointestinal procedure. The instrument includes a housing having an actuator attached thereto and a selectively removable loading unit attached to a distal end of the housing. The loading unit is dimensioned to support an array of surgical fasteners at a distal end thereof. Upon activation of the actuator, the surgical fasteners simultaneously deform against a moveable anvil such that a distal end of each of the surgical fasteners secures each end of each luminal structure to complete the end-to-end anastomosis. As can be appreciated, simultaneous deformation of the surgical fasteners against the movable anvil is advantageous since it greatly reduces overall operating time compared to manual suturing and also provides uniformity across the anastomosis site which tends to reduce leakage. 
     In one embodiment, the surgical fasteners include a convexity and a base leg which cooperate after deformation of the surgical fasteners to securely retain the two luminal structures in close abutment with one another. Preferably, the distal ends of the surgical fasteners penetrate at least one of the ends of one of the luminal structures. In another embodiment, the surgical fasteners include a base leg and a proximal portion and the surgical fasteners are supported in the loading unit in an angular manner relative to a longitudinal axis extending through the loading unit. Upon deformation, the base legs of the surgical fasteners deform at an angle relative to the proximal portions of the surgical fasteners. As can be appreciated, deformation of the surgical fasteners in a radially offset manner allows the surgical fasteners to more fully deform and essentially “pinch” the two adjoining tissues in closer abutment against one another which tends to further enhance the anastomosis and reduce leakage. 
     In yet another embodiment according to the present disclosure, the loading unit is disposable and includes two halves which are pivotable relative to one another. Preferably, the two halves of the loading unit when closed form an elongated aperture for receiving the first luminal structure therethrough. Prior to activation of the actuator, the two halves of the loading unit are pivotally secured relative to one another. Upon actuation, the two halves are unsecured allowing the halves to pivot relative to one another to release the first luminal structure from within the elongated aperture. As can be appreciated, automatically releasing the first luminal structure from the loading unit after deformation is advantageous in the operating theatre since it reduces operating time and manual handling of the luminal structure after the anastomosis which may unintentionally compromise the overall integrity of the end-to-end anastomosis. 
     In still yet another embodiment, the distal end of the loading unit includes an anvil for retaining the distal ends of the surgical fasteners and for supporting an everted end of the first luminal structure. Preferably, the anvil includes an angled surface which causes the distal ends of the surgical fasteners to deform proximally during firing. As mentioned above, this is particularly advantageous because it allows the surgical fasteners to more fully deform and compress or pinch the tissue into tight abutting relationship with one another to enhance the anastomosis. 
     In another embodiment, the loading unit includes a series of elongated channels each having a distal end and a proximal end. Each distal end of each channel is radially offset from each proximal end such that the proximal and distal ends of the surgical fasteners are supported in a radially offset manner within the loading unit. 
     The surgical fasteners are deformable upon activation of the actuator such that a distal end of each surgical fastener secures each end of each luminal structure to complete the end-to-end anastomosis wherein the resulting eversion is exterior to the luminal structures. As can be appreciated, making the eversion exterior to the luminal structures is advantageous since it reduces the chances of fibrin stenosis and/or infection at the anastomosis site. 
     In another embodiment of the present disclosure, the handle includes a locking flange which locks the handle in an actuated configuration. Preferably, the locking flange is bifurcated and cooperates with a release tab to allow the user to selectively release the selectively disposable loading unit. The housing advantageously includes a thumb tab which is movable from a first position for receiving the selectively disposable loading unit to a second position for securing the selectively disposable loading unit. As can be appreciated, these features are advantageous since they tend to greatly simplify the overall operation of the surgical instrument and provide the surgeon with certain lockout controls and safety mechanisms during and after the firing processes. 
     In yet another embodiment, the actuator includes at least one cam member. Preferably, the cam member includes two cam followers which ride along two cam slots defined within the cam member. Advantageously, each cam follower mechanically engages first and second retracting sleeves, respectively, such that movement of the cam follower moves a respective retracting sleeve. 
     Preferably, one of the cam slots includes two cam stages, a first stage for retracting a first retracting sleeve for deformation of the surgical fasteners and a second stage for retracting the first retracting sleeve relative to the second retracting sleeve. Advantageously, movement of the first retracting sleeve in the second stage unsecures the halves of the selectively disposable loading unit to allow the halves to pivot relative to one another to release the first luminal structure from within the aperture. As can be appreciated and as mentioned above, this reduces unnecessary handling of the luminal structures after the anastomosis. 
     The present invention also relates to a method for creating an end-to-end anastomosis between first and second luminal structures. The method includes the steps of: providing a surgical instrument which includes: a housing having an actuator; a disposable loading unit removably mounted to the housing, the disposable loading unit being configured to releasably support a plurality of surgical fasteners; and a retractable anvil being movable to simultaneously deform the surgical fasteners. The method also includes the steps of: inserting an end of the first luminal structure into a passage defined within the loading unit; everting the first luminal structure over the retractable anvil; inserting a distal end of the disposable loading unit into an end of the second luminal structure such that a distal end of each of the plurality of fasteners and the first luminal structure are sufficiently inserted into the second luminal structure and the intimae of the two luminal structures abut one another; and activating the actuator to retract the anvil to simultaneously deform the surgical fasteners and, preferably, to cause distal and/or proximal ends of a plurality of surgical fasteners to penetrate the luminal structures and complete the end-to-end anastomosis wherein the resulting eversion is exterior to the luminal structures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanied drawings. It should be understood, however, that the drawings are designed for the purpose of illustration only and not as a definition of the limits of the invention. 
       An illustrative embodiment of the subject surgical instrument and method are described herein with reference to the drawings wherein: 
         FIG. 1  is a perspective view of a surgical instrument constructed in accordance with an embodiment of the present disclosure; 
         FIG. 2  is an enlarged, partial perspective view of a single use loading unit (hereinafter “SULU”) constructed in accordance with a preferred embodiment of the present disclosure; 
         FIG. 2A  is an enlarged, perspective view of the indicated area of detail of  FIG. 2 ; 
         FIG. 3  is a perspective view of a surgical fastener which is designed for operative engagement with the SULU for creating an end-to-end anastomosis between two luminal vessels; 
         FIG. 4  is a side view the surgical instrument of  FIG. 1 ; 
         FIG. 4A  is a left, side view of a handle/actuator assembly of the surgical instrument of  FIG. 1  shown without a cover plate attached thereto; 
         FIG. 5  is an enlarged, perspective view of a distal end of the actuator assembly shown in a pre-loading position to receivingly engage the SULU; 
         FIG. 6  is a reverse, perspective view of the SULU of  FIG. 2 ; 
         FIG. 6A  is a reverse, perspective view of a lower half of the SULU of  FIG. 2 ; 
         FIG. 7  is a perspective view with parts separated of the SULU of  FIG. 2 ; 
         FIG. 7A  is a greatly enlarged, perspective view of the indicated area of detail of  FIG. 7 ; 
         FIG. 7B  is a greatly enlarged, perspective view of the indicated area of detail of  FIG. 7 ; 
         FIG. 7C  is an enlarged, perspective view of a base portion of a first retracting sleeve; 
         FIG. 7D  is a greatly enlarged, perspective view of the indicated area of detail of  FIG. 7C ; 
         FIG. 8  is a greatly enlarged, perspective view of the indicated area of detail of  FIG. 7 ; 
         FIG. 9  is a greatly enlarged, perspective view of the indicated area of detail of  FIG. 7 ; 
         FIG. 10  is a perspective view of the actuator assembly with the cover plate shown separated; 
         FIG. 11  is a perspective view the actuator assembly of  FIG. 10  shown with parts separated; 
         FIG. 12  is a horizontal cross-sectional view of the surgical instrument of  FIG. 1  shown preloaded for firing; 
         FIG. 13  is a horizontal cross-sectional view of the indicated area of detail of  FIG. 12 ; 
         FIG. 13A  is a greatly enlarged horizontal cross sectional view of the area indicated in detail of  FIG. 13 ; 
         FIG. 14  is a top cross-sectional view of the surgical instrument taken along section line  14 - 14  of  FIG. 12 ; 
         FIG. 15  is a greatly enlarged top cross-sectional view of the area indicated in detail of  FIG. 14 ; 
         FIG. 16  is a front cross-sectional view of the surgical instrument taken along section line  16 - 16  of  FIG. 12 ; 
         FIG. 17  is a perspective view of the SULU with a first luminal structure inserted therethrough; 
         FIG. 18  is perspective of the SULU with an end of the first luminal structure everted over a distal end of the disposable unit being inserted into a second luminal structure; 
         FIG. 19A  is enlarged, cross-sectional view of the second luminal structure; 
         FIG. 19B  is enlarged, cross-sectional view of the first luminal structure shown everted atop the distal end of the SULU; 
         FIG. 20  is a side cross-sectional view showing the first and second luminal structures in position atop the distal end of the SULU prior to activation of the actuator; 
         FIG. 21  is a side view of the actuator assembly without the cover plate during a first firing stage of the instrument and showing the internal movement of a first retractor within the actuator assembly; 
         FIG. 21A  is a side cross-sectional view showing the relevant positions of the internal working components of the actuator assembly after the first firing stage; 
         FIG. 21B  is a side cross-sectional view showing the movement of the SULU during the first firing stage to deform the surgical fasteners; 
         FIG. 21C  is a greatly enlarged side cross-sectional view of the area indicated in detail in  FIG. 21B ; 
         FIG. 21D  is a greatly enlarged perspective view of the surgical fastener shown in a “stapled” configuration; 
         FIG. 21E  is a side view showing the relevant movement of a locking sleeve after the first firing stage; 
         FIG. 22  is a side cross-sectional view of the actuator assembly during the second firing stage and showing the internal movement of a second retractor within the actuator assembly; 
         FIG. 22A  is a side cross-sectional view of the SULU during the second firing stage and showing the movement of a second retracting sleeve which moves as a direct result of the movement of the second retractor to release the surgical fasteners; 
         FIG. 22B  is a greatly enlarged side cross-sectional view showing the retracting movement of a finger-like retention prong which moves as a direct result of the movement of the second retractor; 
         FIG. 23  is a perspective view of the SULU showing the pivotable movement of the two supports which open after firing to release the first luminal structure; 
         FIG. 24A  is a view showing a completed end-to-end anastomosis; 
         FIG. 24B  is an enlarged, schematic view of a completed end-to-end anastomosis utilizing a prior art device showing an eversion on the interior of the luminal structures; 
         FIG. 24C  is an enlarged, schematic view of a completed end-to-end anastomosis utilizing the presently disclosed surgical instrument showing an eversion on the exterior of the luminal structures; 
         FIG. 24D  is side view of a completed end-to-end anastomosis utilizing the presently disclosed surgical instrument; 
         FIG. 25A  is a view showing the surgical fastener staple pattern of the instrument described with respect to  FIGS. 1-24C ; 
         FIG. 25B  is a view showing one possible alternative surgical fastener staple pattern; 
         FIG. 26  is an enlarged cross-section showing the ends of the two luminal structures after anastomosis and engaged between the surgical fastener. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments of the surgical instrument and method disclosed herein will be described in terms of a gastrointestinal procedure wherein an end-to-end circular anastomosis is created by joining two sections of a two luminal structures, e.g., the colon and/or the small intestine. Alternatively, the presently disclosed surgical instrument may also be utilized in performing end-to-end anastomosis of other tubular luminal body structures for other surgical procedures. 
     In the drawings and in the description which follows, the term “proximal”, as is traditional, will refer to the end of the apparatus which is closer to the user, while the term “distal” will refer to the end which is further from the user. 
     Referring now in detail to the drawing figures in which like reference numerals identify similar or identical elements, one embodiment of the present disclosure is illustrated generally in  FIG. 1  and is designated therein as surgical instrument  10 . Surgical instrument  10  includes two principal components, namely, an actuator assembly  20  and a disposable loading unit (“DLU”) or a single use loading unit (“SULU”)  100 , which along with their internal working components, mechanically cooperate to deform a surgical fastener  260  to complete an anastomosis between luminal structures. 
     The particular surgical instrument  10  shown in the various figures is preferably designed to deform an array of surgical fasteners similar to fastener  260  shown in  FIG. 3  which is generally L-shaped and includes a base leg  264  and an upwardly extending support leg  262 . Preferably, base leg  264  includes a distal end  269  which is sufficiently shaped to penetrate a first luminal structure  320  upon deformation of the surgical fastener  260 . The upwardly extending support leg  262  is attached to base leg  264  at a pivot point  265  and includes an inwardly extending prong  267  disposed at its free end designed to surgical fastener  260  in position after the completed anastomosis. It is envisioned that pivot point  265  may also be dimensioned to include a relief or coined section (not shown) which facilitates formation of the surgical fastener  260 . 
     Turning back in detail to  FIG. 3 , a convexity  263  projects inwardly between the base leg  264  and the support leg  262  and is preferably sufficiently dimensioned to cooperate with the base leg  264  to retain the first luminal structure  320  against the second luminal structure  310  in fluid communication after anastomosis as will be explained in greater detail below with respect to  FIGS. 21B ,  24 A and  24 D. It is envisioned that the surgical fastener  260  can be arranged on the SULU in different patterns/arrays depending upon a particular purpose or to achieve a particular result. 
     As best seen in  FIGS. 1 ,  4 ,  10  and  11 , actuator assembly  20  includes a proximal end  24 , a distal end  22  and a housing  26  defined therebetween for storing the internal working components of the actuator assembly  20 . Preferably, a plate  90  covers the internal components of the actuator assembly  20  when assembled. More particularly, housing  26  includes at least one mechanical interface  23   a  which reciprocates with a corresponding mechanical interface  23   b  ( FIG. 10 ) disposed on cover plate  90  to matingly engage the two components  26  and  90 . 
     Actuator assembly  20  also includes a handle  12  which initiates firing of the surgical instrument  10  and a spring-loaded thumb tab  30  for loading the SULU  100  onto the actuator assembly  20  both of which will be explained in greater detail below. Preferably, handle  12  is provided with an ergonomic surface which is contoured and configured to be comfortably gripped by the hand of the user during operation of the instrument. 
     Turning briefly to  FIG. 11  which illustrates in detail the internal working components of the actuating assembly  20  which are preferably assembled and stored within housing  26 . More particularly, the actuating assembly  20  includes a torsion spring  70  which mounts about post  21  which protrudes from housing  26 . Spring  70  includes a lower arm  74  which is biased against a lower portion of the housing and an upper arm  72  which is biased against a rotating two-stage cam  60 . 
     Handle  12  includes a bushing  19  which protrudes laterally from the proximal end of the handle  12  and pivotally engages a corresponding recess  29  disposed within the proximal end  24  of housing  26  to allow pivotal movement of the handle  12  with respect to housing  26 . Handle  12  also includes a vertically extending slot  27  disposed at its proximal end  24  which receives the proximal end of a lever  16  which moves in conjunction with the handle  12 . A pair of flanges  14   a  and  14   b  downwardly extend from the handle  12  and receive lever  16  therebetween. A mechanical interface  11   a  disposed on handle  12  engages a corresponding mechanical interface  11   b  disposed on lever  16  to secure the lever  16  to the handle  12 . Preferably, lever  16  has a first recess  17  shaped to engage and control the movement of the cam  60  during downward movement of the handle  12 , the purpose of which will be explained in more detail with respect to  FIG. 21A . Lever  16  also includes a second recess  15  which helps to limit lateral movement of the torsion spring  70  within housing  26 . 
     As mentioned above, actuating assembly  20  also includes a spring-loaded thumb tab  30  which rests atop housing  26  within a longitudinally extending slot  28  disposed near the distal end  22  thereof. As best seen in  FIG. 10 , slot  28  is formed by notches  18   a  and  18   b  of the housing  26  and cover plate  90 , respectively. Tab  30  includes a thumb guide  35  which cooperates with a sliding sleeve  32  to facilitate proximal movement of the tab  30  for loading the SULU. A downwardly depending flange  34  disposed on tab  30  engages a corresponding slot  33  located in a mount  31  disposed atop the sliding sleeve  32 . Preferably, sliding sleeve  32  includes a post  36  which is dimensioned to receive a tension spring  38  thereon. Spring  38  is biased between a block  47  disposed within housing  26  and a proximal edge  37  of sliding sleeve  32  such that spring  38  biases sliding sleeve  32  to a distal-most position proximate distal end  22 . Preferably, a distal end  39  of sleeve  32  is arcuate or semi-circular and is dimensioned to slidingly engage a corresponding end  82  of a first retractor  80  to lock the SULU  100  within the actuator assembly  20  after the SULU  100  is loaded as will be discussed in more detail below. 
     Actuator assembly  20  also includes first retractor  80  and a second retractor  50  which each move by way of movement of the handle  12  which, in turn, imparts movement to the two-stage cam  60 . First retractor  80  includes distal and proximal ends  82  and  84 , respectively, and is generally tubular in dimension with the exception of an elongated furrow  83  extending proximally from distal end  82  for slidingly supporting sleeve  32 . Retractor  80  also includes a slot  85  for receiving a pin  54  for affixing the retractor  80  to the cam  60  and another pair of slots  87  and  89  located near the proximal end  84  for receiving two cam followers  51   a  and  51   b , respectively. Preferably, the proximal end  84  is bifurcated to facilitate insertion of the second retractor  50  therein. 
     As best seen in  FIGS. 11 and 16 , a guide  81  engages an elongated rib  25   a  in housing  26  and an elongated rib  25   b  in cover plate  90  to slidingly mount the retractor  80  to housing  26 . Guide  81  is dimensioned slightly longer than rib  25   a  to permit proximal movement of the first retractor  80  relative to the housing  26  upon activation of the handle  12 . Preferably, a protective tube  95  is telescopically disposed about the first retractor  80  and moves in conjunction with the sliding sleeve  32  by way of slot  96  which secures mount  31  of the sliding sleeve  32  therein. It is anticipated that protective tube  95  also helps to restrict lateral movement of the first retractor  80  during retraction. Tube  95  also includes an elongated channel  97  which generally aligns with guide  81  located in the first retractor  80  to mount both components to ribs  25   a  and  25   b.    
     It is contemplated that proximal movement of tab  30  will impart reciprocating proximal movement to the sliding sleeve  32  to expose carriages  86  and  88  disposed within the first retractor  80  which are designed to receive a pair of first and second retracting sleeves  110  and  120  ( FIGS. 7-9 ) of the SULU  100 . More particularly, and as best seen in  FIG. 5 , carriage  86  is generally circular in shape and is designed to receive an outer lip  122  formed by the union of end  122   a  and  122   b  of second retracting sleeve  120  of the SULU  100 . Preferably, carriage  86  is dimensioned larger that the lip  122  so as to permit proximal movement of the second retracting sleeve  120  relative to the first retracting sleeve  110  as will be explained in more detail with respect to  FIG. 22A . Carriage  88  is likewise circular in shape and receives outer lip  112  of the first retracting sleeve  110 . 
     Actuator assembly  20  also includes a handle lock  40  which rests atop the first retractor  80  and extends laterally between the housing  26  and the cover plate  90 . More particularly, handle lock  40  is mounted within slots  93   a  and  93   b  as best seen in  FIG. 10 . Handle lock  40  includes a post  43  which receives a spring  45  for biasing handle lock  40  against a ledge  49  of the housing  26  ( FIG. 12 ). Handle lock  40  also includes a pair of flanges  42   a  and  42   b  which align with flanges  14   a  and  14   b  disposed on handle  12 . As shown best in  FIGS. 21 and 22 , downward movement of the handle  12  forces the handle lock  40  initially distally against spring  45  until flanges  14   a  and  14   b  clear flanges  42   a  and  42   b  at which point spring  45  forces handle lock  40  proximally to lock flanges  42   a  and  42   b  atop flanges  14   a  and  14   b  and to lock handle  12  in a downwardly disposed position. Preferably, flanges  42   a  and  42   b  define a slot  41  for receiving lever  16  therebetween. 
     Actuator assembly  20  also includes a second retractor  50  which includes an elongated arm  52  having a key-like distal end  53  and a T-shaped heel section  56 . Preferably, T-shaped heel section  56  attaches to a tension spring  55  disposed proximally thereof. Second retractor  50  is preferably bifurcated at its proximal end forming two longitudinally extending fins  58   a  and  58   b  each having a slot  57  and aperture  59  for receiving cam followers  51  and  51   b , respectively. It is contemplated that spring  55  is biased against an elongated stop  65  which rests atop arm  52  and biases heel section  56  proximally when the second retractor  50  is retracted which will be explained in more detail below with respect to the operation of the surgical instrument  10 . 
     As mentioned above, the first retractor  80  is affixed to two-stage cam  60  by pin  54 . More particularly, cam  60  includes an aperture  61  located near the distal end thereof for receiving pin  54  which affixes the cam  60  to the first retractor  80 . Cam  60  also includes a pair of generally vertical arcuately-shaped slots  62  and  64  which each include two discrete stages, namely  62   a ,  62   b  and  64   a ,  64   b , respectively, for imparting movement to corresponding followers  51   a  and  51   b . A nub  66  is located near the uppermost portion of the cam  60  and is dimensioned to slideably engage recess  17  located in lever  16  as best illustrated in  FIG. 12 . 
     It is contemplated that during downward movement of handle  12 , lever  16  will bias nub  66  downwardly such that nub  66  rides proximally along recess  17  and causes cam  60  to pivot downwardly about pin  54  as shown best in  FIGS. 21A and 22 . In turn, followers  51   a  and  51   b  will ride along slots  64  and  62  and cause the first and second retractors  80  and  50  to move in a proximal direction which will be explained in more detail below. Preferably, recess  17 , nub  66  and slots  64  and  62  can be dimensioned to control the movement and timing of the cam followers  51   a  and  51   b . For example, it is envisioned that the stages  64   a ,  64   b  and  62   a  and  62   b  can be dimensioned to control the timing and movement of the first and second retractors which, in turn, can effect the efficiency of the anastomosis. 
     Elongated stop  65  is preferably affixed to the distal end of cam  60  and rests atop the second retractor  50 . Elongated stop  65  includes a distal end  69  and a proximal end  67  which includes two extending portions  67   a  and  67   b  each having an aperture  63   a  and  63   b , respectively, disposed therethrough. Preferably, end  69  of stop  65  is sufficiently dimensioned such that it engages a corresponding biasing post  102  located within the SULU  100 . 
     Preferably, the second retractor  50 , the cam  60  and the elongated stop  65  are pre-assembled prior to insertion into the first retractor  80 . More particularly and as best illustrated in  FIGS. 10-12 , elongated stop  65  is positioned atop arm  52  of the second retractor  50  between T-shaped heel section  56  and end  53 . Apertures  63   a  and  63   b  of stop  65  align with aperture  61  of cam  60  such that once the cam  60  and the elongated stop  65  are inserted within slot  91  of the first retractor  80 , pin  54  locks the two components  65  and  60  together through slot  85 . 
     Cam  60  is positioned between the extending fins  58   a  and  58   b  of the second retractor  50  such that, when the retractor  50  and cam  60  are inserted within slot  91  of the first retractor, followers  51   a  and  51   b  are inserted through slot  87  and slot  89 , respectively, and slideably couple the two components  50  and  60  within the first retractor  80 . Handle lock  40  is then positioned atop the first retractor  80  as described above. First retractor  80  is then mounted on ribs  25   a  and  25   b  of housing  26  and cover plate  90 , respectively, and tab  30  along with sliding sleeve  32  are engaged thereon. Handle  12  and lever  16  are then assembled as described above and pivotably mounted about post  21 . Spring  70  is then positioned accordingly so as to bias handle  12  against housing  26 . 
     Turning now to  FIGS. 7-9  which show an exploded view of the internal working components of the SULU  100  which as mentioned above includes first retracting sleeve  110  and second retracting sleeve  120  which cooperate to deform fasteners  260  and securely fasten the two luminal structures  320 ,  310  in fluid communication as shown in  FIGS. 24A and 24D . 
     More particularly and as best seen in  FIGS. 7-7D , first retracting sleeve  110  includes a tube-like base  110   a  and an arcuate sleeve cap  110   b  which together define the first retracting sleeve  110 . Base  110   a  includes a circular lip  112  located at its proximal end and a semi-circular anvil  118   a  located at the opposite end. A locking tab  116   a  having an elongated slit  182   a  located therein is disposed between lip  112  and anvil  118   a . A longitudinally-extending slot  114   a  is disposed between the lip  112  and the locking tab  116   a . At least one interface  117   a  downwardly depends from base  110   a  to mechanically engage a corresponding mechanical interface  117   b  disposed on sleeve cap  110   b  ( FIG. 7 ). A flange  113   a  is preferably disposed beneath slot  114   a  and is sufficiently dimensioned to engage corresponding flanges  113   b   1  and  113   b   2  located on sleeve cap  110   b , Slot  114   a  is sufficiently dimensioned to receive a tab  138   a  ( FIG. 13 ) which projects from an upper surgical fastener support  130   a  which is explained in more detail below. 
     Sleeve cap  110   b  includes a semi-circular anvil  118   b  and a bifurcated proximal end  113  composed of flanges  113   b   1  and  113   b   2  which together define a slot  114   b  for receiving a tab  138   b  which projects from a lower surgical fastener support  130   b  which is explained in more detail below. Sleeve cap  110   b  also includes mechanical interfaces  117   b  which couples with corresponding mechanical interfaces  117   a  disposed on base  110   a  to engage sleeve cap  110   b  with base  110   a . A locking tab  116   b  having an elongated slit  182   b  located therein is disposed between proximal end  113  and anvil  118   b . A longitudinally-extending opening  111   b  is preferably disposed proximate locking tab  116   b  and aligns with a corresponding opening  111   a  in base  110   a  ( FIG. 7C ) such that the first luminal structure  320  can be received therethrough as seen best in  FIGS. 17 and 18 . 
       FIGS. 2A and 7D  show a greatly enlarged view of anvil  118   a  which includes a semi-annular array of fastener support channels or cradles  119   a  each configured and dimensioned to support a surgical fastener  260  therein. Sleeve cap  110   b  also includes fastener support channels  119   b  which, when base  110   a  and sleeve cap  110   b  are assembled, align to form a circular array about the internal surfaces of anvil  118   a  and  118   b . It is envisioned that anvils  118   a  and  118   b  can be designed to support different arrays of surgical fasteners  260  depending upon a particular purpose. Each channel  119   a  and  119   b  is preferably separated by an anchor  187   a  and  187   b  ( FIG. 7 ) which releasably retains a projecting finger  124   a ,  124   b  of second retracting sleeve  120  ( FIG. 2A ). 
     Support channels  119   a  and  119   b  each include proximal ends  186   a  and  186   b  and distal ends  184   a  and  184   b  which are radially offset from one another to seat surgical fastener  260  within channels  119   a  and  119   b  in a radially offset manner the purpose of which will be explained below with respect to the operation of the surgical instrument  10 . The distal end  184   a  of each channel  119   a  is preferably arched so as to correspond to the arcuate shape of the end of the surgical fastener  260  as best seen in  FIG. 13A . It is anticipated that arching the distal end  184   a  will cause the surgical fastener  260  to deform upwardly and proximally upon retraction of the first retracting sleeve  110  by the first retractor  80  as explained below with reference to  FIGS. 21-22 . 
       FIGS. 7-7D  also show second retracting sleeve  120  which includes an upper cuff  120   a , a lower cuff  120   b  and an outer cap  128  which together define the second retracting sleeve  120 . More particularly, upper cuff  120   a  includes a semi-annular lip  122   a  at one end and a plurality of retention fingers  124   a  at the opposite end. Upper cuff  120   a  also includes a first slot  101  which preferably aligns with slot  114   a  of the first retracting sleeve  110   a  to receive tab  138   a  of upper fastener support  130   b  therethrough. A second slot  126   a  receives locking tab  116   a  when cuff  120   a  is slideably mounted atop base  110   a . Interfaces  129   a  mechanically engage corresponding interfaces  129   b  located on lower cuff  120   b.    
     Lower cuff  120   b  includes a bifurcated proximal end  107  which comprises flanges  107   b   1  and  107   b   2  which define a slot  108  for receiving tab  138   b  of lower fastener support  130   b  therethrough and a plurality of retention fingers  124   b  which extend from the opposite end thereof. A slot  126   b  is disposed between the flanges  107   b   1 ,  107   b   2  and the fingers  124   b  for receiving locking tab  116   b  of the sleeve cap  110   b  when cuff  120   b  is slideably mounted thereon. A longitudinally-extending opening  121   b  is disposed proximate slot  126   b  and aligns with a corresponding opening  121   a  in upper cuff  120   a  and also aligns with openings  111   a  and  111   b  of the first retracting sleeve  110  such that the first luminal structure  320  can be received therethrough as seen best in  FIGS. 17 and 18 . 
     A semi-circular cuff cap  128  is disposed atop lower cuff  120   b  and Mechanically interfaces with upper cuff  120   a  such that semi-circular lips  122   a  and  122   b  form circular lip  122 . More particularly, cuff cap  128  includes a plurality of detents  123   b  which mechanically engage a corresponding plurality of notches  123   a  located in upper cuff  120   a  such that the cuff cap  128 , upper cuff  120   a  and lower cuff  120   b  all move in unison upon retraction of the second retracting sleeve  120 . Sleeve cap  128  is preferably bifurcated at its distal end forming slot  109  which is dimensioned to receive tab  138   b.    
     As can be appreciated, fingers  124   a  and  124   b  move upon retraction of the second retracting sleeve  120  to release the surgical fasteners  260  after firing. More particularly and as best seen in  FIGS. 2A and 7A , the distal end of each finger  124   a  is forked and includes a first prong  127   a  which retains a surgical fastener  260  within the fastener support channels  119   a  and a second prong  125   a  which interlocks with anchor  187   a  to releasably lock the finger  124   a  to the first retracting sleeve  110  until released by the second retractor  50  ( FIGS. 22A and 22B ) which will be explained in more detail with respect to the operation of the surgical instrument  10 . Likewise, each finger  124   b  of lower cuff  120   b  includes prongs  127   b  and  125   b  which operates in the same manner. 
     As mentioned previously, the SULU  100  also includes fastener support  130  which has an upper support  130   a  and a lower support  130   b  which, when assembled, internally house the first and second retracting sleeves  110  and  120 , respectively, along with their individual working components. Upper support  130   a  and lower support  130   b  each include a distal end  135   a  and  135   b  each having an array of braces  137   a  and  137   b , respectively, which project radially from distal ends  135   a  and  135   b . As best illustrated in  FIG. 2 , each brace  137   a  and  137   b  supports an upwardly extending support leg  262  of a surgical fastener  260  disposed within one of the channels  119   a  or  119   b . A plurality of radially extending slots  139   a  and  139   b  are disposed between each support brace  137   a ,  137   b  for retaining a surgical fastener  260  therein and for restricting unwanted lateral movement of each fastener  260 . It is anticipated that each surgical fastener  260  is positioned within a slot  139   a ,  139   b  such that convexity  263  projects outwardly from brace  137   a ,  137   b  and, after anastomosis, cooperates with the base leg  264  to retain the two luminal structures  32  and  310  in close abutment against one another ( FIGS. 21B ,  24 A and  24 D). 
     Upper support and lower support  130   a  and  130   b , respectively, also include hinges  136   a  and  136   b  which, when the SULU  100  is assembled, matingly engage one another to allow pivotable movement between the supports  130   a  and  130   b  from an open position ( FIG. 23 ) to a closed position ( FIG. 2 ). Preferably, a pin  180  secures the two hinges  136   a  and  136   b  together ( FIG. 6 ). Upper and lower supports  130   a  and  130   b  each include a longitudinally-extending opening  133   a  ( FIG. 23) and 133   b  which aligns with openings  121   a ,  121   b ,  111   a  and  111   b  described above to receive the first luminal structure  320  therethrough as seen best in  FIGS. 17 and 18 . Longitudinally oriented slots  131   a  and  131   b  are disposed adjacent openings  133   a  and  133   b  on the upper and lower support members  130   a  and  130   b , respectively, for receiving locking tabs  116   a  and  116   b  in much the same manner as described above with respect to slots  126   a  and  126   b  of the second retracting sleeve  120 . 
     Lower support  130   b  includes a pair of shoulders  132   a  and  132   b  disposed on opposite sides of opening  133   b  for slideably receiving a corresponding pair of flanges  144   a  and  144   b  associated with an upper locking sleeve  140   a . More particularly, each flange  144   a  and  144   b  extends distally from the upper locking sleeve  140   a  to define a notch  149   a  and  149   b , respectively, therein for receiving shoulders  132   a  and  132   b  of lower support  130   b.    
     Upper locking sleeve  140   a  includes a C-shaped clip  146   a  ( FIG. 8 ) disposed therein which has pair of opposing hooks  147   a  for snap-lockingly engaging slit  182   a  of locking tab  116   a  of first retracting sleeve  110 . A lower locking sleeve  140   b  operates in a similar manner and includes a pair of opposing hooks  147   b  for snap-lockingly engaging slit  182   b  of locking tab  116   b  of first retracting sleeve  110 . Upper locking sleeve  140   a  also includes an opening  141   a  which aligns with openings  133   a ,  133   b ,  121   a ,  121   b ,  111   a  and  111   b  described above to receive the first luminal structure  320  therethrough as seen best in  FIGS. 17 and 18 . It is envisioned that upon retraction of the second retracting sleeve  120 , upper locking sleeve  140   a  will move proximally relative to shoulders  132   b  and  134   b  and disengage shoulders  132   a ,  132   b  which, in turn, will allow the upper and lower supports  130   a  and  130   b  to pivot about pin  180  and release the first luminal structure  320  ( FIGS. 21E and 23 ). This will be explained in greater detail with respect to the operation of the instrument as described below. 
     SULU  100  also includes a biasing post  102  which mechanically aligns upper and lower supports  130   a  and  130   b  in fixed relation relative to one another. More particularly, biasing post  102  includes a proximal end  103  and a distal end  105  and has a vertically oriented cavity  106  disposed therethrough for receiving tabs  138   a  and  138   b  of the upper and lower supports  130   a  and  130   b , respectively. As mentioned above, tabs  138   a  and  138   b  pass through slots  114   a ,  114   b  of the first retracting sleeve  110  and through slots  101 ,  108  and  109  of the second retracting sleeve  120  and mechanically align with one another within cavity  106  as best seen in  FIG. 21B . 
     Turning now in detail to the loading of the SULU  100  within actuator assembly  20  as best seen in  FIG. 5 , thumb tab  30  is moved proximally by way of thumb guide  35  against spring  38  which, in turn, moves sleeve  32  and protective cover  95  proximally to expose carriages  86  and  88 . The SULU  100  is then loaded within actuator assembly  20  by placing lip  112  within carriage  88  and lip  122  within carriage  86 . As best shown in  FIG. 13 , lip  122  is positioned near the distal end of carriage  86  which allows lip  122  and, hence, second retracting sleeve  120 , to move independently from the first retracting sleeve upon activation of the second retractor  50 . In contrast, carriage  88  is dimensioned smaller than carriage  86  such that lip  112  fits snugly within carriage  88 . Once the SULU is positioned within carriages  86  and  88 , thumb tab  30  is released and spring  38  biases sleeve  32  and protective cover  95  distally over lips  112  and  122  to lock the SULU  100  within the actuator assembly  20 . 
     In use and as shown in  FIGS. 17-240 , the user inserts a free end  322  of the first luminal structure, e.g., intestine, into opening  133  of the SULU and pulls via a surgical hook or graspers the free end  322  towards the distal end of the SULU  100 . The user then everts the first luminal structure  320  over the anvils  118   a ,  118   b  of the SULU  100  such that the free end  322  is retained by end  269  of the surgical fasteners  260  (see  FIG. 19B ). Everting of the first luminal structure  320  may be achieved by any suitable known instruments and/or techniques such as by using graspers. The first luminal structure  320  is preferably everted over the full length of the base leg  264  such that the first luminal structure  320  resides in close proximity to convexity  263  as best seen in  FIG. 19B . 
     The first luminal structure  320  is then secured to the distal end of the SULU  100  by a suture or other convention means or by virtue of an additional securing mechanism (not shown) disposed on the SULU  100 . The user then inserts the end of the SULU  100  and the first luminal structure  320  into the second luminal structure  310  such that the distal end  269  of each of the plurality of fasteners  260  and the everted end portions  322  of the first luminal structure  320  are sufficiently inserted into end  312  ( FIGS. 18 and 20A ). As seen best in the enlarged view of  FIG. 20 , the support leg  262 , convexity  263  and prong  267  of each surgical fastener  260  remains outside incision  312 . The instrument is now preset for firing. 
       FIGS. 21-22  show the firing sequence of instrument  10 , i.e., when the handle  12  is depressed by the user. As best shown in  FIGS. 21 and 21A , as handle  12  is depressed downwardly in the direction of reference arrow “A”, lever  16  simultaneously imparts movement to both handle lock  40  and cam  60 . More particularly, downward movement of handle  12  causes flanges  14   a  and  14   b  of lever  16  to urge flanges  42   a  and  42   b  of handle lock  40  distally against spring  45  in the direction of reference arrow “B” ( FIG. 21 ). At the same time, handle  12  causes recess  17  of lever  16  to bias nub  66  which, in turn, causes cam  60  to deflect downwardly and proximally as best seen in  FIG. 21A . Preferably, recess  17  in lever  16  is dimensioned to control the specific movement of nub  66  within recess  17  which, in turn, controls the overall movement of cam  60 . Downward and proximal movement of cam  60  causes cam followers  51   a  and  51   b  to move within the first cam stages  64   a  and  62   a  of slots  64  and  62 , respectively, which, in turn, moves the first retractor  80  and protective cover  95  proximally in the direction of reference arrow B′. 
     As seen best in  FIG. 21 , as retractor  80  moves proximally as a result of the movement of cam followers  51   a  and  51   b  within slots  64  and  62 , slot  85  moves proximally until it abuts pin  54 . Preferably, when slot  85  abuts pin  54 , cam  60  is forced more downwardly about pin  54  such that cam followers  51   a  and  51   b  move more proximally to engage the second stages  64   b  and  62   b  of the cam slots  64  and  62 , respectively. 
     As mentioned above, the first retractor  80  retracts the first retracting sleeve  110  ( FIG. 21 ) which, in turn, causes surgical fasteners  260  to deform as shown in  FIGS. 21B and 21D . More particularly and as best shown in  FIG. 21B , proximal movement of the first retractor  80  causes both the first retracting sleeve  110  and the second retracting sleeve  120  to move proximally relative to biasing post  102  until biasing post  102  abuts the end  69  of elongated stop  65 . As a result, anvils  118   a  and  118   b  deform the distal ends  269  of surgical fasteners  260  upwardly and proximally towards braces  137   a  and  137   b , respectively, i.e., arc-like distal ends  184   a  and  184   b  cause surgical fasteners  260  to deform upwardly and proximally upon retraction of the first retracting sleeve  110 . At the same time, the second luminal structure  310  is forced slightly proximally and extending prongs  267  penetrate to hold the second luminal structure  310  in position as best seen in  FIG. 22A .  FIG. 26  illustrates the resulting deformation of clip  260  through the two luminal structures  320  and  310 . 
     It is anticipated that the radially offset orientation of the opposite ends  186   a ,  186   b  and  184   a ,  184   b  of the support channels  119   a  and  119   b , respectively will cause the opposite ends  267  and  269  of the surgical fasteners  260  to deform at an angle α relative to one another as best shown in  FIG. 21D . This allows end  269  to deform proximal to braces  137   a  and  137   b . Preferably, braces  137   a  and  137   b  have a tapered cross section to deform end  269  of surgical fastener  260  radially from end  267  during deformation. 
     It is anticipated that the presently disclosed surgical fasteners  260  can also include an end  269  which is blunt and which does not penetrate the luminal structures  320  or  310  upon deformation. As can be appreciated, this offers the user the option of performing a less traumatic anastomosis. 
       FIG. 21C  shows the resulting position of the spacer  104  of the biasing post  102  after the first retractor  80  retracts the first and second retracting sleeves  110  and  120 , respectively. More particularly, spacer  104  frictionally locks the first retracting sleeve  110  relative to the second retracting sleeve  120  and prevents the first retracting sleeve  110  from recoiling after firing. 
       FIG. 21E  shows the proximal movement of the locking sleeve  140   a  as a result of the movement of the first retracting sleeve  110 . More particularly, when the first retracting sleeve  110  is retracted proximally, locking tab  116   a  retracts within slot  131   a  of support  130   a  and biases locking sleeve  140   a  in a proximal direction as well as seen by reference arrow “C”. Proximal movement of the locking sleeve  140   a  relative to support  130   a  disengages flanges  142   a  and  144   a  from shoulders  132   b  and  134   b , respectively, of support  130   b  which, in turn, unlocks supports  130   a  and  130   b  from one another thus permitting pivotal movement of the support members  130   a ,  130   b  as best seen in  FIGS. 21E and 23 . 
     Continued downward movement of handle  12  results in both proximal movement of the second retractor  50  and engagement of the handle lock  40  with the handle  12 . More particularly and as best illustrated in  FIG. 22 , as the user continues to move the handle  12  in a downward direction, flanges  14   a  and  14   b  clear corresponding flanges  42   a  and  42   b  and spring  45  biases handle lock  40  proximally in the direction of reference arrow “D” to lock the handle  12  in position. Simultaneously, cam  60  is rotated about pin  54  to a point where the second stages  64   a  and  62   a  of the cam slots  64  and  62  effect the movement of the cam followers  51   a  and  51   b . More particularly, as cam  60  is forced downwardly, the second stage  62   a  of cam slot  62  moves cam follower  51   b  proximally which, in turn, moves the second retractor  50  proximally. The second stage  64   a  of cam slot  64  is generally vertically oriented and, as a result, cam follower  51   a  moves vertically upon continued downward movement of handle  12 . Slot  57  of retractor  50  allows the second retractor  50  to slide proximally relative to cam follower  51   a.    
     As mentioned above, second retractor  50  moves the key-like end  53  of the second retracting sleeve  120  within carriage  86  relative to the first retracting sleeve  110  as illustrated by reference arrow “E” of  FIG. 22A . Proximal movement of the second retracting sleeve  120  retracts the prongs  127   a  and  127   b  of fingers  124   a ,  124   b , respectively, which releases the surgical fasteners  260  as illustrated by reference arrow “E” of  FIG. 22B . 
     It is envisioned that the surgical instrument  10  and/or the SULU  100  may need to be manipulated to assure consistent and tactful release of the surgical fasteners  260  from the SULU. For example, it is contemplated that after and/or simultaneously with activation of the handle  12 , the presently disclosed methods described herein may include the step of manipulating the surgical instrument  10  or SULU  100  relative to the surgical fasteners  260  to facilitate release thereof, e.g., rotational or off-axis manipulation relative to axis “A” (See  FIG. 5 ), vertical manipulation, horizontal manipulation, pivotal manipulation and/or any simultaneous or sequential combination of these aforedescribed manipulative movements. 
     Further, it is contemplated that the surgical instrument  10  or the SULU  100  may be manufactured to include an additional activator, lever, handle, pivot element, linkage or the like (not shown) which upon activation thereof will manipulate the surgical instrument  10  and/or SULU  100  relative to the surgical fasteners  260  in one of the manners described above to facilitate consistent and tactful release of the surgical fasteners  260 . 
     As mentioned above, after sleeve  110  is retracted, locking sleeve  140   a  moves proximally to allow the two supports  130   a  and  130   b  to pivot away from one another as shown in  FIG. 23  to permit the removal of the intestine  320  from within the SULU thereby completing the end-to-end anastomosis as shown in  FIGS. 24A and 24D .  FIG. 26  illustrates a side view of the resulting deformation of surgical fastener  260  through the two luminal structures  320  and  310 . As can be appreciated, the deformation of the surgical fastener  260  forms a series of folds  510  in the tissue  310  which help maintain the anastomosis. 
       FIG. 25A  shows a schematic diagram of the surgical fastener staple pattern which is formed upon actuation of the instrument described above with respect to  FIGS. 1-25B . More particularly, the surgical fasteners are supported by the fastener support braces  137   a ,  137   b  in a normal manner relative to a longitudinal axis “A” ( FIG. 5 ) extending through the SULU. It is envisioned that other surgical fastener staple patterns, e.g., spiral, tangential or angular relative to axis “A”, may be utilized to achieve hemostasis between luminal structures ( FIG. 25B ). For example, it is contemplated that arranging the surgical fasteners  260  in one of the aforedescribed patterns may enable more surgical fasteners  260  to be employed within the same spatial considerations which may achieve a more consistent and/or more reliable hemostasis between luminal structures  320 ,  310 . 
     As can be appreciated, the presently disclosed instrument and method as described herein allows the user to perform an end-to-end anastomosis deep within the colon or small intestine without the need for a gastrotomy and/or other procedures necessary for the proper insertion of the surgical instrument. For example, the presently disclosed instrument  10  may be particularly useful in low anterior resection of the colon whereas prior devices and techniques normally require complex manipulation and positioning of the instrument to reach the low anterior section of the colon and to successfully complete the anastomosis. In many cases, open surgical conditions were required to access the surgical area and properly manipulate the instrument for stapling. 
     As can be appreciated, the a large majority of the prior art end-to-end anastomosis devices produce an eversion  500  which is interior to the lumen, e.g., colon, which may cause fibrin stenosis at the anastomosis site requiring further resection and/or other operative measure to resolve the condition (see  FIG. 24B ). The presently disclosed instrument and method described herein produces an eversion  500  which is exterior to the colon which reduces the likelihood of stenosis at the site (see  FIG. 24C ). Further, a number of known end-to-end anastomotic devices include a knife-like assembly which cuts away healthy tissue beyond the anastomosis to complete the anastomosis. As can be appreciated, the presently disclosed instrument does not include a knife (or the like) to complete the anastomosis hence reducing the amount of healthy tissue lost during the anastomosis. 
     It will be understood that various modifications may be made to the embodiment shown herein. For example, the instrument may be sized to perform an anastomosis for other vessels and luminal tissue. Moreover, although the various internal components of the instrument  10  are shown engaged by particular mechanical interfaces it is envisioned that other types of mechanical interfaces can be employed to achieve the same or similar purpose, e.g., snap-fit, tongue and groove, press fit, etc. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiment. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.