Patent Publication Number: US-2021186510-A1

Title: System for delivering an anvil assembly to a surgical site

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/194,475, filed Nov. 19, 2018, which is a continuation of U.S. patent application Ser. No. 15/831,905, filed Dec. 5, 2017, now U.S. Pat. No. 10,154,845, which is a continuation of U.S. patent application Ser. No. 14/313,283 filed Jun. 24, 2014, now U.S. Pat. No. 9,867,619, the entire contents of each of which are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to a system for delivering an anvil assembly to a surgical site. More specifically, the present disclosure relates to a system for delivering an anvil assembly to a surgical site including a retrieval suture and guide tube. 
     BACKGROUND 
     Surgical anastomosis procedures using a circular stapler often require trans-oral delivery of an anvil assembly to a surgical site. In known procedures, a suture can be attached to the anvil assembly to facilitate retrieval of the anvil assembly from the surgical site after completion of a stapling operation. During such procedures, complications can result if the retrieval suture becomes trapped in the staple line. 
     SUMMARY 
     An anvil assembly delivery system is provided which includes an anvil assembly including a center rod and an anvil head assembly secured to the center rod, and a flexible tube having a first end configured for oral insertion into a patient and a second end. The anvil assembly is connected to the second end of the flexible tube. A retrieval suture is connected to the head assembly and is positioned to extend from the anvil assembly in a direction opposite to the flexible tube. A spacer is supported on the retrieval suture adjacent the anvil head assembly. The spacer is dimensioned to prevent the suture from being clamped between the anvil head assembly and a stapling instrument and becoming trapped in a staple line. 
     In embodiments, the spacer includes a suture tube defining a suture channel and the retrieval suture extends through the suture channel. 
     In certain embodiments, the anvil head assembly is movable from a first tilted position to a non-tilted operative position. 
     In certain embodiments, the suture tube has an outer diameter or thickness of between 0.0625 inches and 0.50 inches. In other embodiments, the suture tube has an outer diameter or thickness of between 0.0625 inches and 0.25 inches. In some embodiments, the suture tube has an outer diameter or thickness of about 0.25 inches. 
     In embodiments, a tensioning member is connected to the anvil head assembly to maintain the anvil head assembly in the first tilted position. 
     In certain embodiments, the anvil head assembly defines first openings and the tensioning member includes a first suture. The first suture extends through the first openings and into an opening in the flexible tube. 
     In embodiments, the anvil head assembly is pivotal from the operative non-tilted position to a second tilted position which is different than the first tilted position. 
     In certain embodiments, the anvil assembly further comprises a rotatable cam member and a plunger. The plunger is spring biased into contact with the cam member and movable distally to rotate the cam member to effect movement of the anvil head assembly from the first tilted position to the operative non-tilted position. 
     In embodiments, the cam member is rotatable and the plunger is movable distally to move the anvil head assembly from the operative tilted position to a second tilted position different than the first tilted position. 
     In certain embodiments, an adapter is provided to connect the anvil assembly to the second end of the flexible tube. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the presently disclosed tilt anvil assembly are disclosed herein with reference to the drawings wherein: 
         FIG. 1  is a perspective view of a surgical stapling device including an embodiment of an anvil assembly according to the present disclosure; 
         FIG. 2  is a first perspective side view of the anvil assembly of  FIG. 1  in the non-tilted position; 
         FIG. 3  is a second perspective side view of the anvil assembly shown in  FIGS. 1 and 2 ; 
         FIG. 4  is an exploded side view of the anvil assembly of  FIGS. 1-3 ; 
         FIG. 5  is an end view of the anvil assembly of  FIGS. 1-3 ; 
         FIG. 6  is a cross-sectional side view of a distal end of the tilt anvil assembly of  FIGS. 1-4  taken along line  6 - 6  of  FIG. 5  and showing the head assembly in the non-tilted operative position; 
         FIG. 7  is a cross-sectional side view of a distal end of the anvil assembly of  FIGS. 1-6  taken along line  7 - 7  of  FIG. 5  and showing the head assembly in the non-tilted operative position; 
         FIG. 8  is an enlarged side view of the cam latch member of the anvil assembly of  FIGS. 1-4 ; 
         FIG. 9  is a top view of the anvil assembly of  FIGS. 1-4  supported on an anvil delivery system; 
         FIG. 10  is an enlarged exploded view of the anvil delivery system of  FIG. 9 ; 
         FIG. 11  an enlarged top view of the anvil delivery system of  FIGS. 9 and 10 , including the anvil assembly of  FIGS. 1-4  shown in the first tilted position tensioned by the suture; 
         FIG. 12  is a cross-sectional side view of the anvil assembly and anvil delivery system of  FIG. 11  taken along lines  12 - 12  of  FIG. 11 ; 
         FIG. 13  is a cross sectional side view (showing the area of detail of  FIG. 12 ) of the anvil assembly of  FIGS. 1-4 , in a pre-fired tilted position supported on the anvil delivery system of  FIG. 9 ; 
         FIG. 14  is an enlarged view of portion  14  of  FIG. 13 ; 
         FIG. 15  is an illustration of the surgical stapling instrument of  FIG. 1  and the anvil delivery system of  FIG. 9  with the anvil delivery system inserted trans-orally into a patient and the stapling instrument inserted through an incision in the stomach; 
         FIG. 16  is an enlarged side view of the distal head portion of the surgical stapling device of  FIGS. 1 and 15 ; 
         FIG. 17  is an enlarged side view of the distal head portion of the surgical stapling device of  FIGS. 1 and 15 , showing the anvil assembly of  FIGS. 1-4  received thereon. 
         FIG. 18  is an enlarged cross-sectional side view of the distal head portion of the surgical stapling device of  FIG. 1 , including the connected anvil assembly of  FIGS. 1-4  shown in an approximated pre-fired non-tilted operative position; 
         FIG. 19  is an enlarged cross-sectional side view of the distal head portion of the surgical stapling device of  FIG. 1 , including the connected anvil assembly of  FIGS. 1-4  shown in a post-fired non-tilted operative position; 
         FIG. 20  is an enlarged cross-sectional side view of the distal end of the anvil assembly of  FIGS. 1-4  in the post-fired non-tilted operative position corresponding to the position of  FIG. 19 ; 
         FIG. 21  is an enlarged cross-sectional side view of the distal end of the anvil assembly of  FIGS. 1-4  in a post-fired second tilted position; 
         FIG. 22  is a cross-sectional side view of the anvil assembly of  FIGS. 1-4  in a post-fired second tilted position (corresponding to the position of  FIG. 21 ) shown supported on an anvil retainer of the surgical stapling device of  FIG. 1 ; 
         FIG. 22A  is another cross-sectional side view of the anvil assembly of  FIGS. 1-4  corresponding to the anvil assembly position of  FIG. 22 ; 
         FIG. 23  is an enlarged view showing the designated area of detail of  FIG. 22A ; 
         FIG. 24  is a side view of the anvil assembly of  FIG. 22  supported on the anvil retainer of the surgical stapling device of  FIG. 1 ; 
         FIG. 25  is a side, perspective view of the anvil assembly including a proximal suture tube; 
         FIG. 26  is an illustration of the surgical stapling instrument of  FIG. 1  and the anvil delivery system of  FIG. 9  with the anvil delivery system, including the proximal suture tube of  FIG. 25 , inserted trans-orally into a patient and the stapling instrument inserted through an incision in the stomach; and 
         FIG. 27  is an enlarged view of the indicated area of detail shown in  FIG. 26 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of the presently disclosed anvil assembly 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. Throughout this description, the term “proximal” will refer to the portion of the instrument closer to the operator and the term “distal” will refer to the portion of the instrument further from the operator. 
       FIG. 1  illustrates an embodiment of a surgical stapling device configured for use with a tilt anvil assembly according to the present disclosure. Briefly, surgical stapling device  10  includes a proximal handle assembly  12 , an elongated central body portion  14  including a curved elongated outer tube  14   a,  and a distal head portion  16 . The length, shape and/or the diameter of body portion  14  and distal head portion  16  may also be varied to suit a particular surgical procedure. 
     With reference still to  FIG. 1 , handle assembly  12  includes a stationary handle  18 , a firing trigger  20 , a rotatable approximation knob  22  and an indicator  24 . A pivotally mounted trigger lock  26  is fastened to handle assembly  12  and is manually positioned to prevent inadvertent firing of stapling device  10 . Indicator  24  is positioned on the stationary handle  18  and includes indicia, e.g., color coding, alpha-numeric labeling, etc., to identify to a surgeon whether the device is approximated and is ready to be fired. Head portion  16  includes an anvil assembly  110  and a shell assembly  31 . A more detailed discussion of surgical stapler  10  is disclosed in U.S. Pat. Nos. 7,364,060 and 7,303,106, the contents of which are incorporated herein by reference in its entirety. 
     Referring now to  FIGS. 2-7 , an embodiment of the anvil assembly of the present disclosure is shown generally as reference numeral  110 . Anvil assembly  110  is shown in a non-tilted or operative position wherein the staple deforming pockets  130  face the staple slots of the instrument. Anvil assembly  110  includes a head assembly  112  and a center rod assembly  114 . Head assembly  112  includes a post  116 , a housing  118 , a backup member or plate  120 , a cutting ring  122 , a cutting ring cover  123 , an anvil plate  124 , a spacer or washer  125 , a cam latch member  126 , and a retainer member  127 . Post  116  is monolithically formed with and centrally positioned within housing  118 . Alternately, housing  118  and post  116  may be formed separately and fastened together using a known fastening technique, e.g., welding. 
     As will be discussed in further detail below, housing  118  includes openings  119   a,    119   b  sized and dimensioned to receive one or more sutures or tensioning members “S”. During use, a first suture “S 1 ” ( FIG. 11 ) is inserted through openings  119   a  and is used to retain head assembly  112  in a retracted or first tilted position ( FIGS. 11 and 12 ) during insertion of anvil assembly  110  within a patient. That is, suture “S 1 ” operates as a tensioning member to maintain the head assembly in the first tilted position. A second suture “S 2 ” is inserted through openings  119   b  and is configured to permit retrieval of tilt anvil assembly  110  from within a patient if desired. During trans-oral insertion of anvil assembly  110 , suture “S 2 ” extends from the mouth of patient, permitting the anvil assembly  110  to be retrieved trans-orally. As shown, second suture “S 2 ” extends in a direction opposite the direction of suture “S 1 ”. 
     With reference still to  FIGS. 2-7 , anvil plate  124  is supported in an outer annular recess  128  of housing  118  and includes a plurality of staple deforming pockets  130  for receiving and deforming staples. At least one tab  124   a  extends radially outwardly from anvil plate  124  and is received within a cutout  132  formed in an outer rim of housing  118 . Tab  124   a  and cutout  132  function to align or properly position anvil plate  124  within annular recess  128  of housing  118 . 
     With particular reference to  FIGS. 4, 6 and 7 , head assembly  112  will be described in detail. Backup plate  120  includes a central opening  134  which is positioned about post  116  within an inner annular recess  136  of housing  118  between post  116  and outer annular recess  128 . Backup plate  120  includes a raised platform  120   a.  Cutting ring  122  includes an opening  122   a  having a configuration substantially the same as platform  120   a.  Although platform  120   a  is illustrated as having a circular shape, other configurations are envisioned, e.g., square, rectangular, triangular, etc. In one embodiment, cutting ring  122  is formed from polyethylene and is fixedly secured to backup plate  120  using, for example, an adhesive, to form a backup plate/cutting ring assembly. Backup plate  120  is formed from a hard material, e.g., a metal. Alternately other materials of construction may be used to construct backup plate  120  and cutting ring  122 . Further, backup plate  120  and cutting ring  122 , in the alternative, can be formed as a single or unitary structure. 
     Still referring to  FIGS. 6 and 7 , a cutting ring cover  123  is secured to an outwardly facing or proximal surface of cutting ring  122  using, for example, an adhesive. In one embodiment, cutting ring cover  123  is formed from a material or materials, which have a hardness greater than that of the cutting ring, e.g., mylar. In one embodiment, cutting ring cover  123  includes two layers of mylar (not shown) which are joined together using an adhesive and a polypropylene coating. Alternately, cutting ring  122  need not have a cover. Cutting ring  122  and backup plate  120  are slidably mounted about post  116 . Backup plate  120  includes a pair of inwardly extending fingers  138  which will be described in further detail below. 
     With reference still to  FIGS. 4, 6 and 7 , retainer member  127  is positioned in inner annular recess  136  between backup plate  120  and a back wall  118   a  of housing  118 . In one embodiment, retainer member  127  is annular and includes a plurality of deformable tabs  127   a  which engage a rear surface of backup plate  120 . Retainer member  127  prevents backup plate  120  and cutting ring  122  from moving or being pushed into inner annular recess  136  of housing  118  until a predetermined force sufficient to deform tabs  127   a  has been applied to the backup plate/cutting ring assembly. The predetermined force can be close to but is less than the force applied by an annular cutting blade of a surgical stapling device when it engages, for example, the cutting ring of anvil assembly  110 . In one embodiment by way of example, the predetermined force is between about ten pounds and about ninety pounds and can be about thirty (30) pounds. When the predetermined force is reached, e.g., during cutting of tissue, backup plate  120  is urged into inner annular recess  136  and compresses retainer member  127 . It is envisioned that other crushable, deformable, collapsible or movement restricting members may be used to retain the backup plate/cutting ring assembly in a fixed position until a predetermined force has been applied to the backup plate/cutting ring assembly. 
     As illustrated in  FIG. 4 , anvil center rod assembly  114  includes a center rod  152 , a plunger  154  and plunger spring  156 . A first end of center rod  152  includes a pair of arms  159  which define a cavity  159   a.  Each arm  159  has a transverse through bore  158  which is aligned with a central longitudinal axis of center rod  152 . Alternately, through bores  158  can be offset from the longitudinal axis of center rod  152 . Post  116  of anvil head assembly  112  is dimensioned to be positioned within cavity  159   a  and also includes a transverse through bore (not shown). A pivot member  162  pivotally secures post  116  to center rod  152  via the through bores such that anvil head assembly  112  may be pivotally mounted to anvil center rod assembly  114 . 
     Turning briefly to  FIG. 8 , cam latch member  126  includes a body  126   a  having a through bore  126   b.  Through bore  126   b  is dimensioned to receive pivot member  162  such that cam latch member  126  is pivotally mounted within transverse slot  172  ( FIG. 3 ) of post  116  about pivot member  162 . Referring now to  FIGS. 3, 6 and 7 , cam latch member  126  includes a first body portion  126   c  which extends partially from slot  172  of post  116  and is positioned to be engaged by a finger  166  of plunger  154 . First body portion  126   c  is configured such that the distance between the surface of first body portion  126   c  and through bore  126   b  increase in a clockwise direction about cam latch member  126 . In this manner, plunger  154  is able to move forward as cam latch member  126  rotates in a clockwise direction. Additionally, this configuration of first body portion  126   c  permits plunger  154  to be retracted as cam latch member rotates in a counter-clockwise direction. Cam latch member  126  also includes an edge  126   f,  including a tab  126   g.  A leading portion of edge  126   f  is configured to be urged into engagement with an inner periphery  120   b  of backup plate  120  by an engagement finger  166  of plunger  154  when anvil head  112  is in its non-tilted or operative position. Tab  126   g  is configured to engage backwall  118   a  of housing  118  to prevent cam latch member  126  from rotating counter-clockwise relative to housing  118 . 
     With reference to  FIG. 6 , plunger  154  is slidably positioned in a bore  164  formed in the first end of center rod  152 . Plunger  154  includes an engagement finger  166  which is offset from the pivot axis of anvil head assembly  112  and biased into engagement with edge  126   c  of cam latch  126 . Engagement of finger  166  with edge  126   c  of cam latch  126  presses a leading portion of edge  126   f  against an inner periphery of back plate  120  to urge anvil head assembly  112  to an operative or non-tilted position on center rod  152 . In this non-tilted position, finger  166  remains spaced proximally from post  116  of anvil assembly  110 . 
     Turning to  FIG. 7 , in the pre-fired operative position of head assembly  112 , i.e. when head assembly  112  has been pivoted to its non-tilted position, fingers  138  formed on backup plate  120  engage protrusions  152   b  adjacent top surface  152   a  of center rod  152  to prevent head assembly  112  from pivoting about pivot member  162 . 
     Anvil head assembly  112  may be tilted a degrees ( FIG. 13 ) relative to anvil center rod assembly  114  to the pre-fired first tilted position by the suture “S 1 ” as described below for insertion. In one embodiment, anvil head assembly  112  is tilted less than ninety degrees and preferably about seventy degrees (70°) in its pre-fired tilted position; however it should be understood that tilting head assembly  112  to other degrees is also contemplated. Tilting of anvil head assembly  112  relative to anvil center rod assembly  114  by the suture S 1  causes cam latch member  126  positioned within the inner periphery of the backup plate  120  to rotate, causing body portion  126   c  of cam latch member  126  to engage finger  166  of plunger  154 . As cam latch assembly  126  rotates counterclockwise (as viewed in  FIG. 14 ) with the tilting of anvil head assembly  112 , plunger  154  is retracted within bore  164  of anvil center rod assembly  114 , thereby compressing spring  156 . In this manner, finger  166  of plunger  154  is distally biased against body portion  126   c  of cam latch member  126 . 
     With reference to  FIGS. 3 and 4 , a second end of center rod  152  includes a bore  180  defined by a plurality of flexible arms  182 . Flexible arms  182  each include an opening  182   a  dimensioned to receive a projection formed on or connected to a shell assembly  31  ( FIG. 18 ). Alternatively, openings  182   a  may be configured to receive a suture for permitting retrieval of anvil assembly  110 . The proximal ends of each of the flexible arms  182  include an internal shoulder  184  dimensioned to releasably engage shell assembly  31  of surgical stapling device  10  to secure anvil assembly  110  to the surgical stapling device. A plurality of splines  186  are formed about center rod  152 . Splines  186  function to align anvil assembly  110  with the staple holding portion of a surgical stapling device. Center rod  152  also includes an annular recessed portion  190  to facilitate grasping of anvil assembly  110  by a surgeon with a grasper. Recessed portion  190  may include a roughened or knurled surface or an overmold to facilitate grasping of anvil assembly  110 . 
     With reference now to  FIGS. 9-12 , a system for delivering anvil assembly  110  within a patient is shown generally as anvil delivery system  50 . Anvil delivery system  50  includes a flexible tube  52  and an adapter  62 . Flexible tube  52  includes an open end  52   a.  Adapter  62  and anvil assembly  110  are supported on open end  52   a  of flexible tube  52 . Open end  52   a  of flexible tube  52  includes a through bore  53  extending therethrough configured to receive a locking pin  54 . In embodiments, locking pin  54  can be omitted. Open end  52   a  further includes an opening  55 , used for alignment of the printing on the tube  50  during manufacture. Closed end  52   b  of flexible tube  52  is configured for trans-oral insertion in a patient. Flexible tube  52  may include markings or other gradations  56  along the length thereof to indicate to a surgeon how much of flexible tube  52  has been received within the patient during insertion and/or to indicate the length of flexible tube  52  remaining in the patient during removal. 
     With particular reference to  FIG. 10 , adapter  62  includes a first end  62   a  configured to be received within open end  52   a  of flexible tube  52  and a second end  62   b  configured to be received within bore  180  formed in center rod  152  of anvil assembly  110 . First end  62   a  includes a series of annular rings  64  configured to frictionally retain first end  62   a  of adapter  62  within open end  52   a  of flexible tube  52 . Second end  62   b  of adapter  62  includes a longitudinal guide member  66  configured to be received between flexible arms  182  formed in center rod  152  of anvil assembly  110 . In addition, second end  62   b  of adapter  62  is sized to allow center rod  152  of anvil assembly  110  to freely slide into and off second end  62   b  of adapter  62 . Adapter  62  further includes a first through bore  70  formed in a central hub portion  62   c  as well as second and third through bores  72 ,  74  formed in first end  62   a.  Through bore  72  is configured to align with through bore  53  formed in open end  52   a  of flexible tube  52  and is sized to receive locking pin  54 . As discussed above, in embodiments the locking pin  54  can be omitted. As such bore  72  can be omitted and adapter  62  can be secured to flexible tube  52  via frictional engagement between rings  64  and an inner surface of the tube  52 . Bore  74  is configured to receive both ends of the suture  51 . Bore  70  can also receive the suture ends to enhance retention. 
     With particular reference now to  FIGS. 10-14 , anvil assembly  110  is supported on anvil delivery system  50 . Securing anvil assembly  110  to anvil delivery system  50  requires that suture “S 1 ” is thread through openings  119   a  (shown also in  FIG. 2 ) formed on anvil head  112  such that first and second ends of suture “S 1 ” are positioned on different sides of center rod  152 . Second end  62   b  of adapter  62  is positioned within through bore  180  of center rod  152  such that longitudinal guide  66  is received between two of arm members  182 . Each of the first and second ends of suture “S 1 ” is inserted through bore  74  ( FIG. 10 ) formed in adapter  64  and through open end  52   a  of flexible member  52 . Anvil head  112  is then rotated to a first tilted position as first and second ends of suture “S 1 ” are pulled through opening  74 , applying tension on the anvil head forcing it to pivot counterclockwise as viewed in the orientation of  FIG. 13 . Such pivoting forces plunger  154  proximally as described above. 
     First end  62   a  of adapter  62  is inserted into open end  52   a  of flexible member  52 . The frictional contact between annular rings  64  of first end  62   a  of adapter  62  and an inner surface of flexible tube  52  secures adapter  62  to flexible tube  52  and prevents suture “S 1 ” from loosening as it is clinched between the outer wall of the adapter  62  and inner wall of flexible tube  52 . It is envisioned that more than one suture may be used to secure anvil head assembly  112  in a pre-fired tilted position. It is also envisioned that the suture S 1  need not be passed through bore  74  but instead is just clamped between the adapter  62  and the inner wall of the flexible tube  52 . 
     With reference also to  FIG. 15 , a method for delivering anvil assembly  110  to a surgical site within a patient will be described. In one method, anvil assembly  110  is provided in the first tilted position supported on anvil delivery system  50  and ready for delivery. Alternatively, a clinician secures anvil assembly  110  to anvil delivery system  50  as discussed above. With anvil assembly  110  secured to flexible tube  52 , the surgeon inserts closed end  52   b  of flexible tube  52  in the patient&#39;s mouth “M” and moves closed end  52   b  along with flexible tube  52  down through esophagus “E” to a surgical site, i.e., the stomach “St”. 
     After insertion, the surgeon then makes a first incision “I 1 ” at the surgical site (stomach “St” as shown) to create an inner access to closed end  52   b  of flexible tube  52  and then pulls closed end  52   b  of flexible tube  52  through first incision “I 1 ”. In some procedures it may be beneficial to pull flexible tube  52  through incision “I 1 ” until center rod  152  of anvil assembly  110  advances through first incision “I 1 ”. When anvil assembly  110  is properly positioned at the surgical site, the surgeon releases anvil delivery system  50  from anvil assembly  110  by cutting suture “S 1 ” and separating anvil assembly  110  from second end  62   b  of adapter  62 . Flexible tube  52  (with fitting  62 ) may then be pulled from the body through first incision “I 1 ”. 
     Severing of suture “S 1 ” permits plunger  154  ( FIG. 13 ) to extend from within bore  164  ( FIG. 6 ), thereby causing finger  166  to engage body portion  126   c  of cam latch member  126 . Rotation of cam latch member  126  (clockwise as viewed in the orientation of  FIG. 14 ) causes edge  126   f  of latch member  126 , engaged with the inner periphery of backup plate  120 , to urge anvil head assembly  112  to return to a non-tilted operative position (e.g. the position of  FIG. 6 ). Additionally, the distal end of stapling device  10  may be configured to engage finger  166  of plunger  154  as anvil assembly  110  is attached to surgical stapling device  10 . In this manner, the distal end of surgical stapling device  10  urges plunger  154  distally, thereby ensuring the rotation of cam latch  126  and anvil head assembly  112  to a non-tilted position. 
     With particular reference to  FIG. 15 , in one method, a second incision “I 2 ” is then formed at the surgical site such that distal head portion  16  of surgical stapling device  10  may be received therethrough. Alternatively, distal head portion  16  of surgical stapling device  10  may be received through first incision “I 1 ” once anvil delivery system  50  has been removed therefrom. 
     Turning briefly to  FIGS. 16 and 17 , anvil assembly  110  is operably received on an anvil retainer  32  extending from shell assembly  31  formed on a distal end of surgical stapling device  10 . Once anvil assembly  110  is received on surgical stapling device  10 , surgical stapling device  10  operates in the manner discussed in U.S. Pat. No. 7,364,060, previously incorporated herein in its entirety by reference. Note that alternatively, suture S 1  can be severed after the distal head portion  16  of the stapling device  10  receives the anvil assembly  110 . After attachment, the rotation knob  22  is rotated to approximate the anvil assembly  110  and distal head portion  16  to clamp tissue therebetween, and then the firing trigger is actuated to fires the staples as disclosed in U.S. Pat. No. 7,364,060. 
     The operation of anvil assembly  110  will now be described with reference to  FIGS. 18-23 . When anvil assembly  110  is in its pre-fired non-tilted position (e.g.  FIG. 18 ), backup plate  120  is spaced from backwall  118   a  of housing  118  by retainer  127  and protrusions  152   b  of center rod  152  engage fingers  138  of backup plate  120  (also shown in  FIGS. 6 and 7 ) to prevent tilting of anvil head assembly  112  about pivot member  162 . Finger  166  of plunger  154  is urged by spring  156  into engagement with body portion  126   c  of cam latch member  126  to urge cam latch member  126  in a clockwise direction (as viewed in  FIG. 18 ), about pivot member  162  such that edge  126   f  of cam latch member  126  engages inner periphery  120   b  of backup member  120 . 
     The firing of surgical stapling device  10  causes a knife blade  33  thereof to engage cutting ring  122  to move cutting ring  122  and backup plate  120  into annular recess  136  of housing  118  of anvil head assembly  112 . Arrows “W” in  FIG. 19  indicate how cutting ring  122  and backup plate  120  move as a result of the firing of surgical stapling device  10 . When such movement occurs, deformable tabs  127   a  of retainer  127  (labeled in  FIGS. 6 and 7 ) are deformed against backwall  118   a  of housing  118  and fingers  138  of backup member  120  move away from protrusions  152   b  of center rod  152 . Further, inner periphery  120   b  of backup plate  120  moves past edge  126   f  of cam latch member  126  such that cam latch member  126  is urged to pivot about pivot member  162  (clockwise as viewed in the orientation of  FIG. 21 ) in the direction indicated by arrow “X” in  FIGS. 21 and 22  by plunger  154  (spring biased distally) to a position in which body portion  126   e  of cam latch  126  is positioned in front of and engages backup plate  120 . Engagement of plunger  154  with cam latch member  126  urges cam member  126  to further rotate clockwise which due to its configuration enables spring biased plunger  154  to move further distally so angled surface  167  of plunger  154  contacts the surface of post  116  of anvil head assembly  112  to move the anvil head assembly  118  to a second tilted position ( FIGS. 22A and 23 ). It is noted that anvil head assembly  112  will not immediately tilt to its second tilted position upon firing of surgical stapling device  10  because, upon firing, anvil head assembly  112  is in an approximated position, i.e., the anvil head assembly  112  is in close alignment with shell assembly  31  of stapling device  10 , and, therefore, does not provide room for head assembly  112  to pivot. As such, the anvil head assembly  112  will only begin to tilt when anvil assembly  110  and shell assembly  31  of surgical stapling device  10  are being unapproximated and there is a sufficient gap between the anvil assembly  110  and the distal head portion  16  of the stapling device  10 . 
     As anvil head assembly  112  pivots towards its forward or second tilted position, finger  166  of plunger  154  maintains surface  126   e  of cam latch member  126  in contact with backup plate  120  to prevent backup plate  120  from sticking to the knife blade as the knife blade is retracted. It is noted that curved surface  126   e  of cam latch member is configured to eliminate any gap and ensure contact between surface  126   e  of cam latch member  126  and backup plate  120  to hold backup plate  120  in place during and after the knife blade is retracted such that the cutting ring and backup plate assembly stay in their correct position during continued tilting of anvil assembly  112 . Anvil assembly  110  is configured such that anvil head assembly tilts to a forward or second tilted position 13 degrees ( FIG. 24 ) relative to center rod assembly  114 . As can be appreciated, the anvil head assembly therefore pivots in a first direction from an initial (first) tilted position to an untilted operative position for application of staples. After firing of the instrument, the anvil head pivots in the same direction to a second tilted position. In one embodiment, anvil head assembly  112  is tilted less than ninety degrees and preferably about seventy degrees (70°) to its second tilted position such that the total pivoting movement of the anvil from the retracted or first tilted position to the forward or second tilted position is about one-hundred and forty degrees (140°). It should however be noted that the tilting of anvil head assembly  112  to other degrees for the first and/or second tilted position is also contemplated. 
       FIGS. 25-27  illustrate an alternate embodiment of the anvil assembly delivery system shown generally as  50 ′ ( FIG. 26 ). Anvil assembly delivery system  50 ′ is substantially identical to anvil delivery system  50  but further includes a spacer supported on the second or retrieval suture “S 2 ”. The spacer is dimensioned to prevent the retrieval suture “S 2 ” from being clamped between the anvil head assembly  112  and a stapling device  10  ( FIG. 1 ) and becoming trapped in a staple line when the stapling device  10  is fired. In one embodiment, the spacer includes a suture tube  210  which will be discussed in further detail below. It is also envisioned that the spacer may comprise any structure which can be supported on the suture “S 2 ” to prevent approximation of the anvil head assembly  112  and the stapling device  10  to a degree to enable firing as will be discussed below. 
     Known stapling devices have lockouts which prevent the surgical stapling device from being fired until the anvil assembly and the shell assembly of the surgical stapling device have been closely approximated into a firing zone. See, e.g., U.S. Pat. No. 7,364,060. Providing a lockout to lock the stapling device to prevent firing of the stapling device until the anvil head assembly and stapling device are approximated into the firing zone ensures that staples ejected from the shell assembly are close enough to contact the anvil assembly  112  and be properly formed by the anvil assembly  112  when fired from the stapling device  10 . 
     In the anvil delivery system  50 ′, the spacer, e.g., suture tube  210 , is supported on the suture “S 2 ” adjacent the anvil head assembly  112 . The suture tube  210  has a thickness or configuration to prevent approximation of the anvil assembly and shell assembly into the firing zone when the spacer  210  is positioned between the anvil assembly and the shell assembly. As such, when the suture “S 2 ” and, thus, the suture tube  210 , is inadvertently clamped between the anvil head assembly  112  and the stapling device  10 , the anvil head assembly  112  is prevented from being approximated in relation to the stapling device  10  into the firing zone to prevent firing of the stapling device  10 . This ensures that the retrieval suture “S 2 ” will not become trapped in the staple line when the stapling device  10  is fired. 
     As discussed above, the retrieval suture “S 2 ” is positioned through the openings  119   b  ( FIG. 25 ) formed in the housing  118  of the head assembly  112  of the anvil assembly  110 . The ends  200  of the suture “S 2 ” extend from the mouth “M” of the patient “P”. In one embodiment, the ends  200  extend through a suture tube  210  and are connected to a reel assembly  202  which is configured to house and manipulate the retrieval suture “S 2 ” during delivery of the anvil assembly  110  to the surgical site. Such a reel assembly is disclosed in U.S. application Ser. No. 14/078,766 which is incorporated herein by reference in its entirety. 
     In use, the suture “S 2 ” is secured to the anvil assembly  110  during delivery of the anvil assembly  110  to a surgical site and during operation of the stapling device  10 . As illustrated, the proximal suture tube  210  defines a suture channel  212  that receives the suture “S 2 ”. The proximal suture tube “S 2 ” is positioned adjacent to the head assembly  112  and functions to prevent the suture “S 2 ” from being clamped between the anvil assembly  110  and the stapling device  10  and getting caught in the staple line as discussed above. More specifically, when the proximal suture tube  210  is positioned between the anvil assembly  110  and the stapling device  10 , the proximal suture tube  210  has a thickness which prevents approximation of the anvil assembly  110  and the stapling device  10  into the firing zone. As such, when the suture tube  210  is clamped between the anvil assembly  110  and the stapling device  10 , the stapling device  10  will be locked out and cannot be fired. In embodiments, the proximal suture tube  210  has an outer diameter or thickness of between 0.0625 inches and 0.50 inches. In other embodiments, the proximal suture tube  210  has an outer diameter or thickness of between 0.0625 inches and 0.25 inches. In some embodiments, the suture tube has an outer diameter or thickness of about 0.25 inches. Alternatively, the suture tube  210  can have any thickness or configuration which prevents the surgical stapling device  10  and anvil assembly from being approximated to within the firing zone. 
     It is noted that, in certain embodiments, the suture tube  210  may extend the full distance, or a substantial portion of the distance, from the anvil assembly to a position externally of a patient&#39;s mouth. In addition to preventing the retrieval suture from becoming trapped in the suture line, such an elongated suture tube  210  also functions to maintain the cleanliness of the suture and prevent contaminants on the suture from contacting the anastomosis during withdrawal of the suture from the surgical site. 
     It will be understood that various modifications may be made to the embodiments disclosed herein. For example, the suture tube  210  need not be tubular but rather can include any structure or configuration attachable to the suture S 2  capable of preventing approximation of the stapling device and the anvil assembly into the firing zone. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.