Patent Publication Number: US-7913891-B2

Title: Disposable loading unit with user feedback features and surgical instrument for use therewith

Description:
FIELD OF THE INVENTION 
     The present invention relates in general to endoscopic surgical instruments including, but not limited to, surgical stapler instruments that have disposable loading units that are capable of applying lines of staples to tissue while cutting the tissue between those staple lines and, more particularly, to improvements relating to such disposable loading units. 
     COMMONLY OWNED PATENT APPLICATION 
     U.S. Patent Application entitled Disposable Loading Unit With Firing Indicator to Steven G. Hall et al., filed on even date herewith, U.S. Patent Application Publication No. US 2009/0206135A1, the disclosure of which is herein incorporated by reference. 
     BACKGROUND 
     Endoscopic surgical instruments are often preferred over traditional open surgical devices since a smaller incision tends to reduce the post-operative recovery time and complications. Consequently, significant development has gone into a range of endoscopic surgical instruments that are suitable for precise placement of a distal end effector at a desired surgical site through a cannula of a trocar. These distal end effectors engage the tissue in a number of ways to achieve a diagnostic or therapeutic effect (e.g., endocutter, grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and energy device using ultrasound, RF, laser, etc.). 
     Known surgical staplers include an end effector that simultaneously makes a longitudinal incision in tissue and applies lines of staples on opposing sides of the incision. The end effector includes a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway. One of the jaw members supports a staple cartridge that has at least two laterally spaced rows of staples. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge. The instrument commonly includes a plurality of reciprocating wedges which, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil. 
     One type of surgical stapling instrument is configured to operate with disposable loading units (DLU&#39;s) that are constructed to support a staple cartridge and knife assembly therein. Once the procedure is completed, the entire DLU is discarded. Such instruments that are designed to accommodate DLU&#39;s purport to offer the advantage of a “fresh” knife blade for each firing of the instrument. Examples of such surgical stapling apparatuses and DLU&#39;s are disclosed in U.S. Pat. No. 5,865,361 to Milliman et al., the disclosure of which is herein incorporated by reference in its entirety. 
     Some prior disposable loading units have a slot in the bottom of the carrier channel that supports the staple cartridge. A portion of the drive beam that supports the blade extends out through the slot and a support foot or member is attached thereto. Numbered lines are printed on the bottom of the carrier to enable the clinician to ascertain the progress of the blade as it is driven through the staple cartridge. While such arrangement enables the clinician to monitor the firing progress, it requires the clinician to always be able to view the bottom of the carrier channel during the operation. However, because such units are capable of rotating, often times the unit may be oriented in such a way as to prevent viewing of the bottom of the carrier rendering such system useless. 
     Moreover, prior surgical stapling apparatuses, such as those disclosed in U.S. Pat. No. 5,865,361 and others, lack means that would enable the clinician to quickly ascertain whether the disposable loading unit was previously used. Such prior surgical stapling apparatuses also lack means for determining how many times a handle assembly was used. Those prior apparatuses also lack means for monitoring the amount of firing force that is being generated during the firing process. 
     Thus, there is a need for a surgical stapling apparatus configured for use with a disposable loading unit and also has means for monitoring the firing progress of the disposable loading unit, regardless of the position of the unit. 
     There is also a need for a disposable loading unit that is equipped with means for determining whether a disposable loading unit has ever been fired. 
     There is still another need for a surgical stapling apparatus that employs a disposable loading unit that has means for indicating the number of times that the surgical stapling apparatus has been fired. 
     Another need exists for a surgical stapling apparatus that has means for indicating the amount of stress experienced by the blade during firing of the instrument. 
     SUMMARY 
     In one general aspect of various embodiments of the present invention, there is provided a disposable loading unit for attachment to a surgical stapling apparatus. In various embodiments, the disposable loading unit may comprise a tool assembly that includes a carrier that has an anvil assembly movably coupled thereto for selective movable travel between open and closed positions relative to the carrier. A staple cartridge is supported in the carrier and operably supports a plurality of staples therein. An actuator member may be movably supported within the tool assembly and be configured to drive the plurality of staples out of the staple cartridge as the actuator member is driven from a starting position to an end position within the tool assembly. The tool assembly may further include an axial drive assembly that has a distal end portion that is constructed to move through the tool assembly and drive the actuator member from the starting to end position in response to a drive motion imparted to the axial drive assembly from the surgical stapling apparatus. The tool assembly may further comprise a spent cartridge indication system that is operably supported in the tool assembly and cooperates with the actuator member to indicate that at least some of the staples have already been driven out of the staple cartridge. 
     In still another general aspect of various embodiments of the present invention, there is provided a disposable loading unit for attachment to a surgical stapling apparatus. In various embodiments, the disposable loading unit includes a carrier that has a housing coupled thereto that is configured for operable attachment to the surgical stapling apparatus. A staple cartridge may be supported in the carrier and an anvil assembly may be movably coupled to the carrier for selective movable travel between open and closed positions relative to the staple cartridge. The disposable loading unit may further comprise an axial drive assembly that has a distal end portion that supports a blade and is constructed to move in a distal direction through the staple cartridge in response to a drive motion imparted to the axial drive assembly from the surgical stapling apparatus. A blade monitoring system may be operably associated with the axial drive assembly and be configured to transmit data relating to strain experienced by the blade to the surgical instrument to which the disposable loading unit is attached. 
     In another general aspect of various embodiments of the present invention, there is provided a surgical cutting and stapling apparatus that may include a handle assembly that has a drive system operably supported therein for selectively generating drive motions. A processor may also be operably supported in the handle assembly. An elongated body may protrude from the handle assembly and be constructed to transmit the drive motions to a disposable loading unit coupled thereto. The elongated body may be further constructed to transmit strain data from the disposable loading unit relating to strain on a blade within the disposable loading unit to the processor. 
     These and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and, together with the general description of various embodiments of the invention given above, and the detailed description of the embodiments given below, serve to explain various principles of the present invention. 
         FIG. 1  is a perspective view of a disposable loading unit embodiment of the present invention. 
         FIG. 2  is an enlarged perspective view of a portion of the disposable loading unit embodiment of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the disposable loading unit embodiment of  FIGS. 1 and 2  taken along line  3 - 3  in  FIG. 1 . 
         FIG. 3A  is a cross-sectional view of a portion of a carrier and an axial drive assembly. 
         FIG. 3B  is a partial bottom view of the carrier and axial drive assembly of  FIG. 3A . 
         FIG. 4  is an exploded assembly view of a portion of the disposable loading unit of  FIGS. 1-3 . 
         FIG. 5  is a perspective view of another disposable loading unit embodiment of the present invention. 
         FIG. 6  is a perspective view of another disposable loading unit embodiment of the present invention. 
         FIG. 7  is a perspective view of another disposable loading unit embodiment of the present invention. 
         FIG. 8  is an enlarged perspective view of a portion of the disposable loading unit embodiment of  FIG. 7 . 
         FIG. 9  is a cross-sectional view of the disposable loading unit embodiment of  FIGS. 7 and 8  taken along line  9 - 9  in  FIG. 7 . 
         FIG. 10  is an exploded assembly view of a portion of the disposable loading unit embodiment of  FIGS. 7-9 . 
         FIG. 11  is a cross-sectional view of another disposable loading unit embodiment of the present invention. 
         FIG. 12  is a perspective view of another disposable loading unit of the present invention with the spent cartridge indicator pin extended. 
         FIG. 13  is a side cross-sectional view of a portion of a disposable loading unit embodiment of the present invention with some components shown in full view for clarity and wherein the spent cartridge indicator pin is completely received within the nose of the staple cartridge. 
         FIG. 14  is another partial side cross-sectional view of the portion of the disposable loading unit of  FIG. 13  with the spent cartridge indicator pin extended. 
         FIG. 15  is a perspective view of another disposable loading unit embodiment of the present invention. 
         FIG. 16  is a bottom perspective view of a portion of a staple cartridge embodiment of the present invention. 
         FIG. 17  is a partial perspective view of an indicator base embodiment of the present invention. 
         FIG. 18  is a bottom perspective view of an actuation sled embodiment of the present invention. 
         FIG. 19  is a side cross-sectional view of a portion of a disposable loading unit embodiment of the present invention with some components shown in full view for clarity and wherein the disposable loading is in an unfired position. 
         FIG. 20  is a bottom plan view of the surgical staple cartridge of the disposable loading unit of  FIG. 19 . 
         FIG. 21  is a side cross-sectional view of a portion of a disposable loading unit embodiment of the present invention with some components shown in full view for clarity and with the anvil in a closed position. 
         FIG. 22  is a bottom plan view of the surgical staple cartridge of  FIG. 21 . 
         FIG. 23  is a side cross-sectional view of a portion of a disposable loading unit embodiment of the present invention during a firing stroke with some components shown in full view for clarity. 
         FIG. 24  is a bottom plan view of the surgical staple cartridge of  FIG. 23 . 
         FIG. 25  is a bottom perspective view of the surgical staple cartridge of  FIG. 24  wherein the spent cartridge indicator pin has been extended indicating that the disposable loading unit has been fired. 
         FIG. 26  is a perspective view of a surgical stapling apparatus embodiment of the present invention. 
         FIG. 27  is a partial cross-sectional view of a surgical staple cartridge of an embodiment of the present invention with some of the components thereof omitted for clarity. 
         FIG. 28  is a side view of the interior of a handle assembly of a surgical stapling apparatus embodiment of the present invention. 
         FIG. 29  is a side view of the handle assembly of  FIG. 28 . 
         FIG. 30  is a perspective view of a surgical stapling apparatus embodiment of the present invention. 
         FIG. 31  is a top view of an axial drive assembly embodiment of the surgical stapling apparatus depicted in  FIG. 30 . 
         FIG. 32  is a side view of the axial drive assembly of  FIG. 31 . 
         FIG. 33  is an exploded assembly view of a portion of the axial drive assembly and a portion of a housing of a disposable loading unit embodiment of the present invention. 
         FIG. 34  is a side elevational view of the portion of the housing depicted in  FIG. 33 . 
         FIG. 35  is an exploded assembly view of a portion of a disposable loading unit and a data transmission body and a portion of a rotatable knob of an embodiment of the present invention with two orientations of the data transmission body shown for clarity. 
         FIG. 36  is an exploded assembly view of a rotatable knob and a portion of a handle assembly of an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Turning to the Drawings, wherein like numerals denote like components throughout the several views,  FIG. 1  depicts a disposable loading unit  16  of the present invention that may be used in connection with a surgical stapling apparatus such as those disclosed in U.S. Pat. No. 5,865,361, the disclosure of which has been herein incorporated by reference. It will be appreciated that the terms “proximal” and “distal” are used herein with reference to a clinician gripping a handle assembly of the surgical stapling apparatus to which the disposable loading unit  16  is attached. Thus, the disposable loading unit  16  is distal with respect to the more proximal handle assembly. It will be further appreciated that, for convenience and clarity, spatial terms such as “vertical”, “horizontal”, “up”, “down”, “right”, and “left” are used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these terms are not intended to be limiting and absolute. 
     As can be seen in  FIG. 1 , the disposable loading unit  16  may generally comprise a tool assembly  17  for performing surgical procedures such as cutting tissue and applying staples on each side of the cut. The tool assembly  17  may include a cartridge assembly  18  that houses a plurality of surgical staples therein. The tool assembly  17  may also include a staple-forming anvil assembly  20  that has an anvil portion  204  that has a plurality of staple deforming concavities (not shown) formed in the undersurface thereof. A cover plate  208  may be secured to a top surface of anvil portion  204  to define an anvil cavity therebetween. The anvil cavity is dimensioned to receive a distal end of an axial drive assembly  212 . The axial drive assembly  212  may comprise a drive beam  266  of the type and construction described in U.S. Pat. No. 5,865,361. A longitudinal slot (not shown) may extend through anvil portion  204  to facilitate passage of retention flange  284  of axial drive assembly  212  into the anvil cavity. A pair of pivot members  211  may be formed on the proximal end of the anvil portion  204  and be configured to be received in slots  213  that are formed in carrier  216  to enable the anvil portion  204  to pivot between the open and tissue-clamping positions. A camming surface (not shown) may be formed on a proximal end of anvil portion  204  and is positioned to engage axial drive assembly  212  to facilitate closing of the anvil assembly  20 . 
     The distal end of drive beam  266  may include a vertical support strut  278  which supports the knife blade  280 , and an abutment surface  283  which engages the central portion of actuation sled  234  during a stapling procedure. Knife blade  280  may be generally positioned to translate slightly behind actuation sled  234  through a central longitudinal slot in staple cartridge  220  to form an incision between rows of stapled body tissue. A retention flange  284  may project distally from vertical strut  278  and support a camming pin  286  at its distal end. Camming pin  286  may be dimensioned and configured to engage camming surface on anvil portion  204  to clamp anvil portion  204  against body tissue. In addition, a leaf spring (not shown) may be provided between the proximal end of the anvil portion  204  and the distal end portion of the housing  200  to bias the anvil assembly  20  to a normally open position. The disposable loading unit  16  may further include a lockout device  288  as described in U.S. Pat. No. 5,865,361. 
     The disposable loading unit  16  may further include a cartridge assembly  18 . The cartridge assembly  18  may generally include a carrier  216  which is dimensioned and configured to receive a staple cartridge  220  therein. Such staple cartridge  220  supports a plurality of fasteners (staples) and pushers as is known in the art. The staple cartridge  220  may be configured as described in U.S. Pat. No. 5,865,361 to accommodate upstanding cam wedges of an actuation sled. A central longitudinal slot may extend along the length of staple cartridge  220  to facilitate passage of a knife blade  280  formed on the axial drive assembly  212 . During operation of the disposable loading unit  16 , the actuation sled translates through longitudinal slots of staple cartridge  220  to advance cam wedges into sequential contact with the pushers that are operably supported in the staple cartridge  220  to cause the pushers to translate vertically within the staple cartridge  220  and urge the fasteners (staples) associated with the pushers into the staple deforming cavities of the anvil assembly  20 . The carrier  216  may also have an elongated bottom slot therethrough through which a portion of the vertical support strut may extend to enable the clinician to view the firing progress of the distal end of the drive beam as is described and shown in U.S. Pat. No. 5,865,361. In addition, firing indicia (numbers, lines, etc.) may be printed or otherwise provided on the bottom of the carrier  216  adjacent the bottom slot for indicating the position of the distal end of the drive beam during the firing sequence as is known in the art. 
     As can also be seen in  FIG. 1 , the disposable loading unit  16  may also have a housing portion  200  that is adapted to snap onto or otherwise be attached to the carrier  216 . The axial drive assembly  212  may include an elongated drive beam  266  that has a distal working head  268  and a proximal engagement section  270 . The proximal end of housing  200  may include engagement nubs  254  for releasably engaging elongated body of a surgical stapling apparatus. Nubs  254  form a bayonet type coupling with the distal end of the elongated body portion of the surgical stapling apparatus as described in U.S. Pat. No. 5,865,361. The drive beam  266  may be constructed from a single sheet of material or, preferably, from multiple stacked sheets. Engagement section  270  may include a pair of engagement fingers  270   a  and  270   b  that are dimensioned and configured to mountingly engage a pair of corresponding retention slots  272   a  formed in a drive connector  272 . Drive connector  272  may include a proximal porthole (not shown) that is configured to receive the distal end of a control rod as discussed in U.S. Pat. No. 5,865,361. The control rod may impart a driving motion and a retraction motion to the axial drive assembly  212  in a known manner to drive the axial drive assembly  212  from a start position wherein the knife blade has not been advanced through any tissue and an end position wherein the distal end of the axial drive assembly  212  has advanced through the staple cartridge  220  to fire all of the staples therein and sever the tissue clamped between the cartridge  220  and the anvil  20  and then back to the start position. 
     As can be most particularly seen in  FIGS. 1-4 , the disposable loading unit  16  may also include a firing indicator assembly  300 . As was discussed above, prior units employed a slot in the bottom of the carrier to enable the clinician to ascertain the progress of the blade as it is driven through the staple cartridge. While such arrangement enables the clinician to monitor the firing progress, it requires the clinician to always be able to view the bottom of the carrier channel during the operation. However, because such units are capable of rotating, often times the unit may be oriented in such a way as to prevent viewing of the bottom of the carrier rending such system useless. Various embodiments of the present invention solve that problem. For example, in various embodiments of the present invention, the firing indicator assembly  300  may include an axially extending opening  301  formed along the top dead center of the housing  200 . In some embodiments, a transparent window  302  may be mounted (e.g., glued, snapped, etc.) in the opening  301 . In other embodiments, no window is provided. In the embodiment depicted in  FIGS. 1-4 , the engagement section  270  has an indicator  310  formed thereon that is adapted to ride in the opening  301  and is viewable through the window  302 . A firing scale  320 , which may comprise various forms of indicia  322  (e.g., numbers, letters, colors or combinations of numbers, letters and/or colors), may be provided on the housing  200 . The indicia  322  may be located at positions on the housing  200  to enable the clinician to assess the progress of the firing process (i.e., the distance that the axial drive assembly  212  has been advanced axially through the staple cartridge  220 ) by viewing the position of the indicator  310  relative to the indicia  322 . 
     Those of ordinary skill in the art will appreciate that the firing indicator assembly  300  may be employed on disposable loading units that also have the slot  217  through the bottom of the carrier  216  which enables a portion of the vertical strut  278  to extend therethrough. A support member  287  is attached to the bottom of the vertical strut  278 . See  FIGS. 3A and 3B . Bottom firing indicia  279  may be provided adjacent the slot  217  to enable the clinician to monitor the advancement of the axial drive assembly also when viewing the bottom of the disposable loading unit. By combining these features with the firing indicator assembly  300  of the present invention, the clinician is able to monitor the firing progress regardless of whether the clinician is able to view the top of the unit or the bottom of the unit. 
     Other firing indicator arrangements  300 ′ of the present invention comprise an axially extending anvil slot  209  through the anvil cover plate  208  that enables the clinician to view the of retention flange  284  of axial drive assembly  212  as the axial drive assembly is driven from the start position to the end position through the cartridge  220 . Although one continuous axial slot  209  is illustrated, in various other embodiments, the slot  209  may comprise a series of slot segments (not shown). Anvil firing indicia  322 ′ may be provided on the anvil cover  208  adjacent the slot  209 . In still other embodiments, to enhance the visibility of the retention flange, the retention flange  284  may be provided with a color  211  that differs from a color  213  of the anvil assembly  20 . 
       FIG. 5  illustrates yet another firing indicator arrangement  300 ″. As can be seen in that Figure, a movable firing indicator  390  is retained on the anvil cover  208  and is arranged to be contacted by the retention flange  284  as the axial drive assembly  212  is driven from the start position to the end position. Thus, the clinician may monitor the firing progress by viewing the position of the firing indicator  390  on the anvil  20 . The person of ordinary skill in the art will understand that such an indicator  390  may also serve to strengthen the anvil cover assembly  208 . In alternative embodiments, the indicator  390 ′ may be movably mounted within the slot  209 . See  FIG. 6 . 
     Although the disposable loading units describe above comprise a non-articulatable loading unit, the person of ordinary skill in the art will understand that the advantages provided by the firing indicator assemblies  300 ,  300 ′ and/or  300 ″ may be easily employed in connection with known articulatable disposable loading units such as those disclosed in U.S. Pat. No. 5,865,361 and others. 
       FIGS. 7-9  illustrate another disposable loading unit  16 ′ that may be substantially similar to the disposable loading unit described above, except for the differences noted below. For example, in this embodiment, the firing indicator assembly  300  lacks window  302 . In various embodiments, the opening  301  may be located more to one lateral side of the housing  200 ′ and the indicator  310 ′ may actually protrude out through the opening  301  and have a pointer  312  formed thereon to coincide with the indicia  322 . Thus, in this embodiment, the indicator  310 ′ runs off of top dead center of the housing  200 ′ to enhance the ability of the clinician to view the indicator  310 ′ from one lateral side of the disposable loading unit  16 ′. As can be seen in  FIG. 9 , in various embodiments the indicator  310 ′ protrudes from the drive connector  272 . In an alternative disposable loading unit  16 ″ as depicted in  FIG. 11 , a second opening  304  is provided through housing  200 ′ on the opposing lateral side through which opening  301  extends. A second indicator  310 ″ is attached to the drive connector  272  and protrudes through the opening  304 . The second indicator  310 ″ may also have a pointer  312 ″ formed thereon that coincides with indicia  322 ′ provided adjacent the second opening  304  in correspondence with the first indicia  322 . Such arrangement permits the clinician to assess the progress of the firing process from either lateral side of the disposable loading unit  16 ″. Again, this embodiment may also be employed in connection with articulatable disposable loading units without departing from the spirit and scope of the present invention. 
       FIGS. 12-14  illustrate another disposable loading unit embodiment  116  of the present invention that may be substantially similar to the disposable loading unit embodiment  16  described above or to those disposable loading units described in U.S. Pat. No. 5,865,361, except for the unique and novel differences noted below. In particular, the disposable loading unit  116  includes a tool assembly  17 ′ that includes a carrier  216  that supports a staple cartridge  220 ′ therein. An anvil assembly  20  may be pivotally attached to the carrier  216  for selective movable travel between open and closed positions relative to the carrier  216  in the manner discussed above. In various embodiments, the tool assembly  17 ′ may include a spent cartridge indication system  400  of the present invention.  FIGS. 13 and 14  illustrate a distal portion of the staple cartridge  220 ′ in cross-section. Staple cartridge  220 ′ may comprise a staple cartridge  220  of the type and construction disclosed in U.S. Pat. No. 5,865,361, except for the provision of the spent cartridge indication system  400 . 
     Staple cartridge  220 ′ supports a plurality of fasteners and pushers as is known in the art. A plurality of spaced-apart longitudinal slots may extend through staple cartridge  220 ′ to accommodate upstanding cam wedges of an actuation member or sled  234  that is movably supported within the tool assembly  17 ′ and which is selectively movable from a staring position to an end position therein. A central longitudinal slot  282  extends along the length of staple cartridge  220  to facilitate passage of a knife blade  280  formed on the axial drive assembly  212 . During operation of the disposable loading unit  116 , actuation sled  234  translates through longitudinal slots of staple cartridge  220 ′ to advance the cam wedges of the actuation sled  234  into sequential contact with the pushers that are operably supported in the cartridge  220 ′ to cause the pushers to translate vertically within the cartridge  220 ′ and urge the fasteners (staples) associated with the pushers into the staple deforming cavities of the anvil assembly  20 . The distal end of drive beam  266  includes a vertical support strut  278  which supports the knife blade  280 , and an abutment surface  283  which engages the central portion of actuation sled  234  to impart a driving motion thereto during a stapling procedure. Surface  285  is located at the base of surface  283  and is configured to receive a support member  287  that is slidably positioned along the bottom of the carrier  216 . Knife blade  280  is generally positioned to translate slightly behind actuation sled  234  through a central longitudinal slot  282  in staple cartridge  220  to form an incision between rows of stapled body tissue. 
     As can be seen in  FIGS. 13 and 14 , the spent cartridge indication system  400  may comprise a spent cartridge indicator pin  420  that is supported within the distal end  410  of the staple cartridge  220 ′. The indicator pin  420  may have a proximal abutment end  422  for abutting contact by the actuation sled  234 , a tapered central portion  424 , and an indicator portion  426 . The indicator pin  420  is received in a hole  412  in the distal end  410  that has a tapered hole segment  414 .  FIG. 13  illustrates the position of the actuation sled  234  before it has reached the end position and the indicator pin is in an “unfired” position. When the staple cartridge  220 ′ has not yet been fired, the indicator portion  426  of the indicator pin  420  may be completely received within the nose portion  410  of the staple cartridge  220 ′. As the actuation sled  234  reaches the end position, the actuation sled  234  pushes on the abutment end  422  of the indicator pin  420  causing the tapered portion  424  thereof to lockably engage the internal tapered portion  414  of the hole  412 . Thus, the indicator portion  426  of the indicator pin  420  will be pushed out of the distal end  410  of the staple cartridge  220 ′ to a “fired” position and is retained in that position to indicate to the clinician that the staple cartridge  220 ′ has been spent or previously fired. See  FIG. 14 . Such arrangement enables the clinician to quickly determine whether the disposable loading unit  116  has been previously fired. Those of ordinary skill in the art will appreciate that the unique and novel spent cartridge indication system may be effectively employed in connection with articulatable and non-articulatable disposable loading units alike. 
       FIGS. 15-25  illustrate another disposable loading unit  516  of the present invention that may be substantially similar to the disposable loading unit  16  described above or to those disposable loading units described in U.S. Pat. No. 5,865,361, except for the unique and novel differences noted below. In particular, the disposable loading unit  516  includes a tool assembly  17  that comprises a carrier  216  that supports a staple cartridge  220 ″ therein. An anvil assembly  20  is pivotally supported relative to the carrier  216  and is selectively movable between open and closed positions relative thereto. The tool assembly  17  may further comprise a spent cartridge indication system  400 ′. Staple cartridge  220 ″ may comprise a conventional staple cartridge of the type and construction disclosed in U.S. Pat. No. 5,865,361, except for the differences noted below. 
     As indicated above, staple cartridge  220 ″ supports a plurality of fasteners (staples) and pushers as is known in the art. A plurality of spaced-apart longitudinal slots  235  ( FIG. 20 ) extend through staple cartridge  220 ″ to accommodate upstanding cam wedges  232  of an actuation member or sled  234 ′. See  FIG. 18 . A central longitudinal slot  282  extends along the length of staple cartridge  220 ″ to facilitate passage of a knife blade  280  formed on the axial drive assembly  212 . See  FIG. 20 . During operation of the disposable loading unit  516 , actuation sled  234 ′ translates through longitudinal slots  235  of staple cartridge  220 ″ to advance the cam wedges  232  of the actuation sled  234 ′ into sequential contact with the pushers that are operably supported in the cartridge  220 ″ to cause the pushers to translate vertically within the cartridge  220 ″ and urge the fasteners (staples) associated with the pushers into the staple deforming cavities of the anvil assembly  20 . The distal end of drive beam  266  includes a vertical support strut  278  which supports the knife blade  280 , and an abutment surface  283  which engages the central portion of actuation sled  234  during a stapling procedure. See  FIG. 19 . Surface  285  is located at the base of surface  283  and is configured to receive a support member  287  that is slidably positioned along the bottom of the carrier  216 . Knife blade  280  is generally positioned to translate slightly behind actuation sled  234 ′ through a central longitudinal slot  282  in staple cartridge  220  to form an incision between rows of stapled body tissue. 
     In various embodiments, the spent cartridge indication system  400 ′ may comprise an indicator base  600  that is movably supported within the tool assembly  17  as shown in  FIG. 16 . The indicator base  600  may have a longitudinal slot  602  therein that enables the vertical support strut  278  of the axial drive assembly  212  to pass therethrough. In addition, the indicator base  600  may have a pair of stiffening rails  604  protruding therefrom. In various embodiments, for example, the indicator base  600  may be stamped from metal or otherwise fabricated from other suitable materials. As can be seen in  FIG. 17 , the proximal end  606  of the indicator base  600  may be staggered to accommodate the staggered wedges  232  of the actuation sled  234 ′. The proximal end  606  of the indicator base  600  is adapted to be received in a recess  630  formed in the bottom of the actuation sled  234 ′. See  FIG. 18 . As can also be seen in  FIG. 18 , a pair of shear stops  632  are formed in the bottom of the actuation sled  234 ′ to engage the distal end  606  of the indicator base  600 . More specifically to engage the distal ends  605  of the stiffening rails  604 . 
     The distal end  610  of the indicator base  600  has a spent cartridge indicator pin  611  protruding distally therefrom. The indicator pin  611  may have a distal portion  614  and a locking cone portion  612 . The distal portion  614  is sized to be slidably received in a hole  414 ′ provided in the distal end  410 ′ of the staple cartridge  220 ″. Hole  414 ′ further has a tapered portion  415 ′ that is oriented to engage the locking cone portion  612  as will be discussed below. 
     As can be seen in  FIGS. 16 and 19 , when the staple cartridge  220 ″ is in the unfired position, distal end  610  of the indicator base  600  is received within the recess  630  in the actuation sled  234 ′. A camming surface  209  is formed on a proximal end of anvil portion  204  and is positioned to engage axial drive assembly  212  to facilitate closing of the anvil assembly  20 . See  FIG. 19 . As is discussed in U.S. Pat. No. 5,865,361, the anvil assembly  20  is closed by driving the axial drive assembly  212  in the distal direction “DD” such that the camming pin  286  engages the camming surface  209  and pivots the anvil assembly  20  closed. Often times during a procedure, however, the clinician must open and close the anvil assembly  20  multiple times to manipulate tissue and to grasp and clamp the target tissue between the anvil assembly  20  and the staple cartridge  220 ″. Thus, the anvil assembly  20  may be opened and closed several times before the clinician desires to commence the firing process. In various embodiments, therefore, to avoid actuation of the indicator system  400 ′ during the opening and closing actions, a gap “G” is provided between the shear stops  632  and the corresponding proximal ends  605  of the stiffening rails  602 . See  FIG. 20 . It will be understood that the gap “G” facilitates movement of the axial drive assembly  212  and actuation sled  234 ′ in the distal direction “DD” a sufficient distance to cause the anvil assembly  20  to pivot closed without distally advancing the indicator base  600  from a “prefired” position ( FIGS. 19 and 20 ) to a “fired” position ( FIG. 23 ). 
     Operation of the spent cartridge indication system  400 ′ will now be described with reference to  FIGS. 19-25 .  FIGS. 19 and 20  illustrate the position of the indicator base  600  and the actuation sled  234 ′ prior to closing the anvil assembly  20 .  FIGS. 21 and 22  illustrate the positions of the indicator base  600  and the actuation sled  234 ′ after the axial drive assembly  212  has been advanced distally to close the anvil assembly  20 . As can be seen in those Figures, the proximal ends  605  of the stiffening bars  602  are adjacent to their corresponding shear stops  632 .  FIGS. 23 and 24  illustrate the positions of the indicator base  600  and the actuation sled  234 ′ after the firing sequence has commenced. As can be seen in those Figures, as the axial drive assembly  212  is driven in the distal direction “DD”, the shear stops  632  contact the distal ends  605  of the stabilizing bars  602  on the indicator base  600  driving the indicator base  600  in the distal direction “DD” such that the indicator pin portion  614  protrudes out of the hole portion  414 ′ and the locking cone portion  612  engages the tapered hole portion  415 ′ in the staple cartridge nose  410 ′. After the locking cone portion  612  becomes seated in the tapered hole portion  415 ′, further advancement of the axial drive assembly  212  in the distal direction “DD” causes the shear stops  632  to shear off of the actuation sled  234 ′ (or move to an orientation that permits the actuation sled  234 ′ to continue to move distally relative to the indication base  600 ). See FIGS.  24  and  25 . Thus, the indicator pin  614  of the indicator base  600  will be pushed out of the distal end  410 ′ of the staple cartridge  220 ″ and retained there to indicate to the clinician that the staple cartridge  220 ″ has been spent or previously fired. Such arrangement enables the clinician to quickly determine whether the disposable loading unit  516  has been previously fired. Those of ordinary skill in the art will appreciate that the unique and novel spent cartridge indication system may be effectively employed in connection with articulatable and non-articulatable disposable loading units alike. 
       FIG. 26  illustrates a surgical stapling apparatus embodiment  1000  of the present invention that has a disposable loading unit  1016  embodiment of the present invention coupled thereto. The surgical stapling apparatus  1000  may comprise a handle assembly  12  that has an elongated body  14  protruding therefrom. The handle assembly  12  and the elongated body  14 , as well as the components that make up such elements, may generally operate in the manner discussed in U.S. Pat. No. 5,865,361, except for the differences discussed below. In this embodiment, the disposable loading unit  1016  employs a surgical staple cartridge  1220 . The surgical staple cartridge embodiment  1220  may be substantially similar to surgical staple cartridge  220  described above, except for the improvements discussed below. In particular, as illustrated in  FIG. 27 , in this embodiment, a conventional switch  1224  (e.g., pressure switch, magnetic switch, etc.) may be positioned within the distal end  1222  such that when the actuation member or sled  234  contacts the switch  1224  or comes into close proximity therewith, a signal is transmitted through a wire or wires  1226  to an indicator  1230  mounted in the handle assembly  12 . A power source  1240 , such a battery, may be mounted in the handle assembly  12  and be coupled to the switch  1224 , such that when the switch  1224  is activated, power is permitted to travel from the power source  1240  through the switch  1224  to the indicator  1230 . The indicator  1230  may comprise a light or other suitable indication means to indicate to the clinician that the disposable loading unit  1016  has been fired. Those of ordinary skill in the art will appreciate that the staple cartridge  1220  embodiment may be effectively employed in connection with articulatable and non-articulatable disposable loading units alike without departing from the spirit and scope of the present invention. 
       FIGS. 28 and 29  illustrate another surgical stapling apparatus embodiment  1310  of the present invention that has a handle assembly  1312 . The construction and operation of various components located within the handle assembly  1312  are discussed in U.S. Pat. No. 5,865,361. In addition to those components, the handle assembly  1312  of the present invention includes a first strain gauge  1320  that operably interfaces with the driving pawl  42  that engages the toothed rack  48  on the actuation shaft  46 . The first strain gauge  1320  is electrically coupled to a processor  1330  that receives the inputs form the first strain gauge  1320  and calculates an amount of trigger pressure in pounds per square inch (PSI) associated with each activation of the movable handle  24 . The processor displays the calculated trigger pressure on a trigger pressure display  1322  mounted in the handle assembly  1312 . See  FIG. 29 . 
     The handle assembly  1312  may further support an impedance bar  1340  and a displacement encoder  1342  that is constrained to move on or adjacent to the impedance bar  1340 . In various embodiments, for example, the encoder  1342  may be mounted to a proximal end of the actuation shaft  46  for travel therewith. Thus, as the actuation shaft  46  is advanced in the distal direction “DD” (which results from ratcheting the movable handle portion  24  as discussed in U.S. Pat. No. 5,865,361), the signals from the encoder  1342  are communicated to the processor  1330 . A first switch  1400  may be mounted relative to the impedance bar  1340  such that as the actuation shaft  46  is moved distally a distance required to close the anvil assembly  20 , the first switch  1400  may be triggered by the encoder  1342  or other trigger arrangement mounted to the actuation shaft  46 . The first switch  1400  may be electrically coupled to the processor  1300  which may be coupled to an indicator light (not shown), a speaker  1410  and/or a vibrator  1420  mounted on the handle assembly  1312 . Thus, when the anvil assembly  20  has been moved to a closed position, the processor  1300  may provide the user with an indication in the form of a sound through the speaker  1410  and or vibration motion through vibrator  1420 . 
     As can be seen in  FIG. 29 , the handle assembly  1312  may also include a light screen or light emitting diode screen  1350 . As the actuation shaft  46  is driven in the distal direction “DD” during the firing of the apparatus  1310 , the light band  1352  on the screen  1350  will grow in the distal direction. The clinician can then determine the position of the actuation shaft  46  during the firing process based upon how far the light band  1352  extends distally on the screen  1350 . Thus, when the actuation shaft  46  has been moved to its distal-most position and the disposable loading unit coupled thereto has been completely fired, the light band  1352  may extend completely across the screen  1350 . Utilizing the input from the encoder  1342 , the processor  1330  may also calculate the number of times that the handle assembly  12  has been fired and display that information on a display  1360 . See  FIG. 29 . 
       FIGS. 30-36  illustrate another surgical stapling instrument embodiment  1500  that is equipped with a blade monitoring system  1700  of the present invention. As can be seen in  FIG. 30 , the surgical stapling instrument  1500  may include a handle assembly  1312  of the type and construction described above with a blade monitoring system  1700  of the present invention incorporated therein. As can also be seen in  FIG. 30 , the surgical stapling instrument  1500  may include a disposable loading unit  1516  that is constructed for removable attachment to the elongated body  14  that protrudes from the handle assembly  12 . The disposable loading unit  1516  may generally comprise a tool assembly  17  for performing surgical procedures such as cutting tissue and applying staples on each side of the cut. The tool assembly  17  may include a cartridge assembly  18  that houses a plurality of surgical staples therein. The tool assembly  17  may also include a staple-forming anvil assembly  20  of the type and construction described above. The disposable loading unit  1516  may also include an axial drive assembly  1512  that may have the attributes of the axial drive assembly described in U.S. Pat. No. 5,865,361 with the improvements described below. 
     In various embodiments for example, the axial drive assembly  1512  comprises a drive beam  1566 . As can be seen in  FIG. 32 , the distal end of drive beam  1566  may include a vertical support strut  1578  which supports the knife blade  1580 . A retention flange  1584  may project distally from vertical strut  1578  and support a camming pin  1586  at its distal end. Camming pin  1586  may be dimensioned and configured to engage a camming surface on the anvil assembly  20  to clamp the anvil assembly  20  against body tissue in a known manner. The drive beam  1566  may be constructed from a single sheet of material or, preferably, from multiple stacked sheets and have an engagement end  1570 . Engagement end  1570  may include a pair of engagement fingers  1570   a  and  1570   b  which may be dimensioned and configured to mountingly engage a pair of corresponding retention slots formed in drive member as is known. The drive member facilitates interconnection of the drive beam  1566  to a control rod  52  when the proximal end of disposable loading unit  1516  is coupled to the elongated body  14  of the surgical stapling apparatus  1500 . 
     The disposable loading unit  1516  may further include a housing assembly  1600  that may comprise an upper housing segment  1610  and a lower housing segment  1620  that are interconnected together to form the housing portion  1600 . The upper housing segment  1610  and the lower housing segment  1620  may be interconnected by adhesive, snap features, fasteners, etc. As can be seen in  FIG. 33 , the upper housing segment  1610  may have an elongate groove  1612  therein to receive a portion of the drive beam  1566  therein. Likewise, the lower housing segment  1620  may have an elongate groove  1622  therein for receiving a portion of the drive beam  1566  therein. 
     As can be most particularly seen in  FIG. 32 , the blade monitoring system  1700  may comprise a strain gage  1710  that is mounted to the vertical strut portion  1578  adjacent the blade  1580 . The strain gage  1710  may have a pair of gage leads  1712  that extend along the drive beam  1566  and terminate in interface terminals  1714  adjacent the engagement end  1570  of the drive beam  1566 . The gage leads  1712  are arranged for electrical contact with conductive traces  1614  and  1624  in the housing segments  1610  and  1620 , respectively, when the drive beam  1566  is received within the elongate grooves  1612  and  1622 . As can be seen in  FIGS. 33 and 34 , the conductive trace  1614  terminates in an upper reload terminal  1616  provided on a proximal end portion  1602  of the housing  1600 . Likewise, the conductive trace  1624  terminates in a lower reload terminal  1626  provided on the proximal end portion  1602  of the housing  1600 . 
     In various embodiments, the elongated body  14  supports a data transmission body  1650  which is configured to operably support the control rod  52  therein. As can be seen in  FIG. 35 , the data transmission body  1650  may have a distal end  1652  that is configured for removable attachment with the proximal end  1602  of the housing  1600  similar to the bayonet-type connection described in U.S. Pat. No. 5,865,361. As can be seen in  FIGS. 30 and 36 , a rotatable knob  28  may be mounted on the forward end of the handle assembly  1312  to facilitate rotation of elongated body  14  with respect to handle assembly  1312  about longitudinal axis “L-L” of the stapling apparatus  1500 . The rotatable knob  28  may be formed from knob segments  28   a  and  28   b  that are fastened together by snap features, adhesive, fasteners, etc. The knob segments  28   a  and  28   b  may each have a radial projection  132  formed thereon that is adapted to extend into corresponding openings (not show) in an outer casing  124  of the elongated body  14  and into depressions  1662   a ,  1662   b  in a proximal end  1660  of the data transmission body  1650 . Projections  132  fixedly secure rotation knob  28  and the elongated body  14  in relation to each other, both longitudinally and rotatably. Rotation of rotation knob  28  with respect to handle assembly  1312  thus results in corresponding rotation of elongated body  14  about longitudinal axis L-L with respect to handle assembly  1312 . It will also be appreciated that because the disposable loading unit  1516  is coupled to the distal end of the elongated body  14 , rotation of the elongated body  14  also results in the rotation of the disposable loading unit  1516 . 
     As can be seen in  FIG. 35 , the data transmission body  1650  has a right data lead  1670  that penetrates through the distal end  1652  to form a lower body penetration  1672  that is oriented for electrical contact with the lower reload terminal  1626  when the proximal end  1602  of the housing  1600  is coupled to the distal end  1652  of the data transmission body  1650 . Likewise, the data transmission body  1650  further has a left data lead  1680  that penetrates through the distal end  1652  to form an upper body penetration  1682  that is oriented for electrical contact with the upper reload terminal  1616  when the proximal end  1602  of the housing  1600  is coupled to the distal end  1652  of the data transmission body  1650 . The right data lead  1670  extends through the data transmission body  1650  and terminates in mounting depression  1662   a  to form a right termination end  1674  and the left data lead  1680  extends through the data transmission body  1650  and terminates in the other mounting depression  1662   b  to form a left terminal end  1684 . See  FIG. 35 . 
     As can be further seen in  FIGS. 35 and 36 , the right knob segment  28   a  has a right hand shroud lead  1690  supported therein that terminates at a proximal right terminal end  1692 . The right hand shroud lead  1690  also terminates through the projection  132  formed in the right hand knob segment  28   a  such that when the projection  132   a  extends into the depression  1662   a  in the proximal end  1660  of the data transmission body  1650 , an electrical connection is formed between the right hand shroud lead  1690  and the right termination end  1664 . Likewise, the left hand knob segment  28   b  has a left hand shroud lead  1700  supported therein that terminates at a proximal left terminal end  1702 . The left hand shroud lead  1700  also terminates through the projection  132   b  formed in the left hand knob segment  28   b  such that when the projection  132   b  extends into the depression  1662 , an electrical connection is formed between the left hand shroud lead  1700  and the left termination end  1684 . 
     In various embodiments, the distal end portion  1313  of the handle assembly  1312  has a right conductive annular band  1810  thereon which is connected to the processor  1330  by a lead  1812  and a left conductive annular band  1820  which is also connected to the processor by a lead  1822 . The right knob segment  28   a  has an inwardly extending attachment flange portion  29   a  formed thereon adapted to be received in an annular groove  1315  formed in the distal end  1313  of the handle assembly  1312 . Similarly, the left knob segment  28   b  has an inwardly extending attachment flange portion  29   b  formed thereon adapted to be received in the annular groove  1315 . Thus, when the right knob segment  28   a  is coupled to the left knob segment  28   b  (by adhesive, snap features, fasteners, etc., the attachment flange portions  29   a ,  29   b  serve to retain the knob  28  on the housing  1312  while facilitating rotational travel of the knob  28  relative thereto. In addition, when the knob  28  is rotatably supported on the handle assembly  1312 , the right terminal end is in electrical contact with the right conductive annular band  1810  and the left terminal end is in electrical contact with the left conductive annular band  1820 . Thus, when the disposable loading unit  1516  is coupled to the elongate body  14 , electrical connections are established between the strain gage  1710  and the processor  1330 . 
     As the axial drive assembly  1512  is driven distally through tissue clamped in the tool assembly  17 , the blade  1580  will experience forces “F” the magnitude of which may depend upon the amount of tissue clamped in the tool assembly  17 . See  FIG. 32 . Such forces “F” will tend to elongate the vertical support strut  1578  which supports the knife blade  1580 . As the forces “F” are applied to the vertical support strut  1578 , the strain gauge  1710  will detect an amount of strain experienced by the vertical support strut  1578  and communication such data to the processor  1330 . The processor  1330  then manipulate the strain data in a known manner and transmits the data on a display  1322  mounted in the handle assembly  1312 . In other embodiments, the processor  1330  can activate the vibrator  1420  to cause the vibrations of the vibrator to increase as the amount of strain experienced by the vertical support strut  1578  and the blade  1580  increase. Thus, the blade monitoring system  1700  provides feedback to the clinician during the operation of the instrument concerning the magnitude of strain being experienced by the blade which is related to the amount of and type of tissue clamped within the tool assembly  17 . 
     While several embodiments of the invention have been described, it should be apparent, however, that various modifications, alterations and adaptations to those embodiments may occur to persons skilled in the art with the attainment of some or all of the advantages of the invention. For example, according to various embodiments, a single component may be replaced by multiple components, and multiple components may be replaced by a single component, to perform a given function or functions. This application is therefore intended to cover all such modifications, alterations and adaptations without departing from the scope and spirit of the disclosed invention as defined by the appended claims. 
     Any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material. 
     The invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. The embodiments are therefore to be regarded as illustrative rather than restrictive. Variations and changes may be made by others without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such equivalents, variations and changes which fall within the spirit and scope of the present invention as defined in the claims be embraced thereby.