Patent Publication Number: US-2023132795-A1

Title: Systems and methods for preventing tissue migration in surgical staplers

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 17/857,515, filed on Jul. 5, 2022, which is a continuation of U.S. patent application Ser. No. 17/700,599, filed on Mar. 22, 2022, which claims the priority benefit of U.S. Provisional Patent Application No. 63/164,837, filed Mar. 23, 2021, which are hereby incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     The disclosed inventive subject matter relates in general to medical devices and surgical instruments and more specifically to systems, devices, and methods associated with surgical staplers used for bariatric surgery performed using laparoscopic techniques. 
     Vertical sleeve gastrectomy is a commonly performed type of bariatric surgery in which a surgical stapling instrument is used to remove a portion of the stomach and staple the remaining portion of the stomach closed. Stapling instruments used for this procedure typically include an upper jaw that is connected to a lower jaw at one end thereof using a hinge. Such devices usually include a tissue stop at or near the hinge to prevent the undesirable migration of tissue into the hinged region of the stapler during use. More recently developed stapling instruments such as the TITAN® SGS23R (Standard Bariatrics) and similar instruments include an upper jaw that is connected to a lower jaw at two locations, namely at both ends of the jaws. Staplers having this design include a distal tissue stop and a proximal tissue stop formed on the lower jaws thereof. However, when in the stapler is in an open position, an area exists between the jaws adjacent to the proximal tissue stop into which tissue may migrate during use of the instrument. This migration may continue until a certain degree of closure is reached, at which point the upper jaw engages the proximal tissue stop of the lower jaw to create a tissue barrier. If a surgeon inadvertently closes the stapler on stomach tissue outside the portion of the instrument that ejects staples, transection of tissue without mechanical fastening thereof with staples may result. If this situation is not recognized by the surgeon during the medical procedure, post-operative complications such as leaks may occur. Because this is an undesirable outcome, an additional barrier or other means of preventing tissue migration in surgical stapling instruments would be beneficial. 
     SUMMARY 
     The following provides a summary of certain example implementations of the disclosed inventive subject matter. This summary is not an extensive overview and is not intended to identify key or critical aspects or elements of the disclosed inventive subject matter or to delineate its scope. However, it is to be understood that the use of indefinite articles in the language used to describe and claim the disclosed inventive subject matter is not intended in any way to limit the described inventive subject matter. Rather the use of “a” or “an” should be interpreted to mean “at least one” or “one or more”. 
     One implementation of the disclosed technology provides a system for preventing unwanted tissue migration in surgical staplers, comprising a surgical stapler having an end effector for dispensing surgical staples, wherein the end effector includes an upper jaw the upper jaw including a proximal end and a distal end; a lower jaw, the lower jaw including a proximal end and a distal end, wherein the distal end of the upper jaw is connected to the distal end of the lower jaw, and wherein the proximal end of the upper jaw is connected to the proximal end of the lower jaw; a first tissue stop formed on the distal end of the lower jaw; a second tissue stop formed on the proximal end of the of the lower jaw, wherein the second tissue stop and the proximal end of the upper jaw define a no tissue zone when the surgical stapler is in an open position; and a tissue cutting device disposed within the lower jaw for resecting tissue; and a warning, blocking, impeding, or barrier forming device for preventing the unwanted migration of tissue into the no tissue zone during surgical procedures such that resection of unstapled tissue is prevented. 
     The warning, blocking, impeding, or barrier forming device may include at least one warning label placed on the stapler for alerting a user of the stapler to the no tissue zone. The warning, blocking, impeding, or barrier forming device may include a flexible sheath, wherein the flexible cape is placed partially or completely around the proximal ends of the upper and lower jaws while permitting the opening and closing thereof. The warning, blocking, impeding, or barrier forming device may include a rigid shield, wherein the rigid shield is formed on or attached to the proximal end of the upper jaw. The warning, blocking, impeding, or barrier forming device may include a flexible band attached to the upper jaw and to the lower jaw and extending therebetween, and wherein at least a portion of the flexible band is located in front of the second tissue stop. The warning, blocking, impeding, or barrier forming device may include a post extending between the upper jaw and the lower jaw at the front end of the second tissue stop, wherein the post either rotates or telescopes when the jaws open and close. The warning, blocking, impeding, or barrier forming device may include a curved or hinged closure link extending between the proximal ends of the upper jaw and the lower jaw. The warning, blocking, impeding, or barrier forming device may include a sacrificial band of compliant material, block of compliant material, or compliant balloon positioned between the proximal ends of the upper jaw and the lower jaw. The warning, blocking, impeding, or barrier forming device may include a non-sacrificial block of rigid material or piece of expandable material positioned between the proximal ends of the upper jaw and the lower jaw and adapted to permit the tissue cutting device to pass therethrough. 
     Another implementation of the disclosed technology provides a system for preventing unwanted tissue migration in surgical staplers, comprising a surgical stapler having an end effector for dispensing surgical staples, wherein the end effector includes an upper jaw the upper jaw including a proximal end and a distal end; a lower jaw, the lower jaw including a proximal end and a distal end, wherein the distal end of the upper jaw is connected to the distal end of the lower jaw, and wherein the proximal end of the upper jaw is connected to the proximal end of the lower jaw; a first tissue stop formed on the distal end of the lower jaw; a second tissue stop formed on the proximal end of the of the lower jaw, wherein the second tissue stop and the proximal end of the upper jaw define a no tissue zone when the surgical stapler is in an open position; and a tissue cutting device disposed within the lower jaw for resecting tissue; and a mechanism for preventing the unwanted migration of tissue into the no tissue zone during surgical procedures such that resection of unstapled tissue is prevented. 
     The mechanism may disengage the tissue cutting device before it reaches the no tissue zone. The mechanism may stop the tissue cutting device before it reaches the no tissue zone and reverses its direction of travel toward the distal end of the lower jaw. The mechanism may use software or software and sensors associated with the operation of the stapler for detecting the presence of tissue within the no tissue zone and taking corrective action. The system may also include audible, visual, or tactile indicators, or various combinations thereof, that are triggered by the software or software and sensors when the presence of tissue is detected within the no tissue zone. 
     Another implementation of the disclosed technology provides a method for preventing unwanted tissue migration in a surgical stapler having an end effector for dispensing surgical staples, wherein the end effector includes an upper jaw having proximal end and a distal end; a lower jaw having a proximal end and a distal end, wherein the distal end of the upper jaw is connected to the distal end of the lower jaw, and wherein the proximal end of the upper jaw is connected to the proximal end of the lower jaw; a first tissue stop formed on the distal end of the lower jaw; a second tissue stop formed on the proximal end of the of the lower jaw, wherein the second tissue stop and the proximal end of the upper jaw define a no tissue zone when the surgical stapler is in an open position; and a tissue cutting device disposed within the lower jaw for resecting tissue, the method comprising providing a warning, blocking, impeding, or barrier forming device for preventing the unwanted migration of tissue into the no tissue zone during surgical procedures such that resection of unstapled tissue is prevented; or providing a mechanism for preventing the unwanted migration of tissue into the no tissue zone during surgical procedures such that resection of unstapled tissue is prevented. 
     The warning, blocking, impeding, or barrier forming device may include at least one warning label placed on the stapler for alerting a user of the stapler to the no tissue zone. The warning, blocking, impeding, or barrier forming device may include a flexible sheath, wherein the flexible cape is placed partially or completely around the proximal ends of the upper and lower jaws while permitting the opening and closing thereof. The warning, blocking, impeding, or barrier forming device may include a rigid shield, wherein the rigid shield is formed on or attached to the proximal end of the upper jaw. The warning, blocking, impeding, or barrier forming device may include a flexible band attached to the upper jaw and to the lower jaw and extending therebetween, and wherein at least a portion of the flexible band is located in front of the second tissue stop. The warning, blocking, impeding, or barrier forming device may include a post extending between the upper jaw and the lower jaw at the front end of the second tissue stop, wherein the post either rotates or telescopes when the jaws open and close. The warning, blocking, impeding, or barrier forming device may include a curved or hinged closure link extending between the proximal ends of the upper jaw and the lower jaw. The warning, blocking, impeding, or barrier forming device may include a sacrificial band of compliant material, block of compliant material, or compliant balloon positioned between the proximal ends of the upper jaw and the lower jaw. The warning, blocking, impeding, or barrier forming device may include a non-sacrificial block of rigid material or piece of expandable material positioned between the proximal ends of the upper jaw and the lower jaw and adapted to permit the tissue cutting device to pass therethrough. The mechanism may disengage the tissue cutting device before it reaches the no tissue zone. The mechanism may stop the tissue cutting device before it reaches the no tissue zone and reverses its direction of travel toward the distal end of the lower jaw. The mechanism may use software or software and sensors associated with the operation of the stapler for detecting the presence of tissue within the no tissue zone and taking corrective action Audible, visual, or tactile indicators, or various combinations thereof, that are triggered by the software or software and sensors when the presence of tissue is detected within the no tissue zone, may also be provided. 
     It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein and may be implemented to achieve the benefits as described herein. Additional features and aspects of the disclosed system, devices, and methods will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the example implementations. As will be appreciated by the skilled artisan, further implementations are possible without departing from the scope and spirit of what is disclosed herein. Accordingly, the drawings and associated descriptions are to be regarded as illustrative and not restrictive in nature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated into and form a part of the specification, schematically illustrate one or more example implementations of the disclosed inventive subject matter and, together with the general description given above and detailed description given below, serve to explain the principles of the disclosed subject matter, and wherein: 
         FIGS.  1 A and  1 B  depict, in an exploded view and a perspective view, respectively, an example surgical stapler that is hinged at two locations along the length of the stapler and that includes a no tissue zone into which tissue may unwantedly migrate during surgical procedures such as laparoscopic bariatric surgery; 
         FIG.  2    depicts the surgical stapler of  FIG.  1 A , wherein a physical label has been placed on the lower jaw of the stapler indicating that “no tissue” is to be situated within the labeled region; 
         FIG.  3    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in a closed position and wherein a flexible tissue-blocking sheath has been partially wrapped around the upper and lower jaws of the stapler; 
         FIG.  4    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein a flexible tissue-blocking sheath has been partially wrapped around the upper and lower jaws of the stapler; 
         FIG.  5    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in a closed position and wherein a flexible tissue-blocking sleeve has been circumferentially wrapped around the upper and lower jaws of the stapler; 
         FIG.  6    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein a flexible tissue-blocking sleeve has been circumferentially wrapped around the upper and lower jaws of the stapler; 
         FIG.  7    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein a flexible, braided, tissue-blocking sleeve has been circumferentially wrapped around the upper and lower jaws of the stapler 
         FIG.  8    depicts the upper jaw of the stapler of  FIG.  1 A , wherein a recessed region has been formed therein for accommodating a flexible sheath or sleeve; 
         FIG.  9    depicts the stapler of  FIG.  1 A  in a closed position, wherein the tissue cutting knife, also referred to as an I-beam or I-shaped blade, is visible near the distal pin; 
         FIG.  10    depicts a mechanical method for stopping the I-Beam from crashing into the distal pin when reversing the knife, wherein the threads on the firing lead screw stop distally, passively limiting the reverse travel of the firing nut; 
         FIG.  11    depicts a mechanical method for stopping the I-Beam from striking the distal pin when reversing the knife, where the threads on the firing lead screw stop distally, passively limiting the reverse travel of the firing nut, but where the firing screw compression spring is mobile rather than fixed; 
         FIG.  12    depicts the stapler of  FIG.  1 A , where the jaws of the stapler are shown in a closed position and where a tissue-blocking anvil cap has been formed or placed on the upper jaw of the stapler; 
         FIG.  13    depicts the stapler of  FIG.  1 A , where the jaws of the stapler are shown in an open position and wherein a tissue-blocking anvil cap has been formed or placed on the upper jaw of the stapler; 
         FIG.  14    depicts an implementation that prevents the transection of tissue without closure thereof with surgical staples through the use of a cantilever beam; 
         FIG.  15    depicts an implementation that utilizes a reversing knife approach to preventing the transection of tissue without closure thereof with surgical staples through the inclusion of a secondary thread on the primary firing screw; 
         FIG.  16    depicts an implementation that utilizes a reversing knife approach to preventing the transection of tissue without the closure thereof with surgical staples through the inclusion of a secondary fine thread on an auxiliary firing screw; 
         FIG.  17    depicts the stapler of  FIG.  1 A , where the jaws of the stapler are shown in an open position and where a tissue-blocking elastomeric band has been mounted on an attachment screw on the upper jaw and an attachment screw on the lower jaw; 
         FIG.  18    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein a tissue-blocking elastomeric band has been mounted on two attachment screws on the upper jaw and two attachment screws on the lower jaw in a crossed configuration; 
         FIG.  19    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein a tissue-blocking elastomeric band has been mounted an attachment screw on the upper jaw and two attachment screws on the lower jaw in a triangular configuration; 
         FIG.  20    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein a tissue-blocking rotating post has been positioned between the upper and lower jaws of the stapler; 
         FIG.  21    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and where a tissue-blocking telescoping post has been positioned between the upper and lower jaws of the stapler; 
         FIG.  22    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and where a tissue-blocking curved linkage has been positioned between the upper and lower jaws of the stapler; 
         FIG.  23    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and where a tissue-blocking passive curved linkage has been positioned between the upper and lower jaws of the stapler; 
         FIG.  24    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and where a tissue-blocking pivoting double linkage has been positioned between the upper and lower jaws of the stapler; 
         FIG.  25    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and where a tissue-blocking sacrificial cut band has been positioned between the upper and lower jaws of the stapler; 
         FIG.  26    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein a tissue-blocking split band has been positioned between the upper and lower jaws of the stapler; 
         FIG.  27    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein a tissue-blocking compliant sacrificial foam block has been positioned between the upper and lower jaws of the stapler; 
         FIG.  28    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein a tissue-blocking compliant sacrificial balloon has been positioned between the upper and lower jaws of the stapler; 
         FIG.  29    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein a zero-clearance block has been positioned between the upper and lower jaws of the stapler; 
         FIG.  30    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein an accordion-like tissue blocking device has been positioned between the upper and lower jaws of the stapler; 
         FIG.  31    depicts the stapler of  FIG.  1 A , wherein the jaws of the stapler are shown in an open position and wherein an alternate accordion-like tissue blocking device has been positioned between the upper and lower jaws of the stapler; 
         FIG.  32    depicts an implementation that utilizes disengaging I-beam knife approach (normal orientation) to prevent the transection of tissue without the closure thereof with surgical staples; 
         FIG.  33    depicts an implementation that utilizes a disengaging I-beam knife approach, shown in a disengaged orientation, to prevent the transection of tissue without the closure thereof with surgical staples; and 
         FIG.  34    depicts an implementation that utilizes an external device or introducer sheath to shield a no tissue zone. 
     
    
    
     DETAILED DESCRIPTION 
     Example implementations are now described with reference to the Figures. Reference numerals are used throughout the detailed description to refer to the various elements and structures. Although the following detailed description contains many specifics for the purposes of illustration, a person of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the disclosed inventive subject matter. Accordingly, the following implementations are set forth without any loss of generality to, and without imposing limitations upon, the claimed subject matter. 
     As previously stated, surgical stapling instruments such as the TITAN® SGS23R (Standard Bariatrics) include an upper jaw that is connected to a lower jaw at two locations, namely at both ends of the jaws. Staplers having this design can include a distal tissue stop and a proximal tissue stop formed on the lower jaws thereof. However, when the stapler is in an open position, an area may exist between the jaws adjacent to the proximal tissue stop into which tissue may migrate during use of the instrument. This migration may be problematic if a surgeon inadvertently closes the stapler on stomach tissue that has migrated outside the portion of the instrument that ejects and secures tissue with staples. In such an area, where tissue has not been stapled, transection of tissue may still progress resulting in a potentially dangerous unstapled portion of the transected tissue. If this situation is not recognized by the surgeon during the medical procedure, post-operative complications such as leaks may occur. Disclosed implementations provide various structural and mechanical systems, devices, and methods for preventing the unwanted migration of tissue when staplers such as the TITAN® SGS23R are used in laparoscopic bariatric surgery. 
     Staplers compatible with the disclosed technology are described in U.S. Pat. No. 10,687,814, which is incorporated by reference herein in its entirety, for all purposes. Some implementations of the staplers disclosed in U.S. Pat. No. 10,687,814 include end effectors that are attached to a support tube that is attached to a handle that includes an actuator for the instrument. As shown in the Figures of U.S. Pat. No. 10,687,814, example end effectors found on surgical staplers include an upper jaw connected to a lower jaw by a simple hinge at the distal end of the stapler and by a master link or rigid link at the proximal end of the stapler. The upper jaw may include an anvil assembly that further includes an anvil frame, an anvil plate, and an anvil plate channel formed therein. The lower jaw may include a cartridge assembly that further includes a cartridge frame, a cartridge plate with a cartridge plate channel formed therein, and a cartridge for containing surgical staples. The cartridge frame may include a first tissue stop and a second tissue stop as well as first and second cartridge pins. A blade assembly that includes a cutting blade is disposed within the cartridge assembly. The master link may include a master link pin that cooperates with a master link slot. 
       FIGS.  1 A- 1 B  depict[[s]] example surgical stapler having end effector  100  (e.g., TITAN® SGS23R), which includes upper jaw  120 , lower jaw  140 , blade/knife assembly  170 , and master link  180 . Upper jaw  120  includes anvil assembly  122 , which further includes anvil frame  124 , anvil plate  126 , and anvil plate channel  128 . Lower jaw  140  includes cartridge assembly  142 , which further includes cartridge frame  144 , cartridge plate  146 , cartridge  150 , distal tissue stop  152 , proximal tissue stop  154 , distal cartridge pin  156 , and proximal cartridge pin  158 . Distal cartridge pin  156  connects upper jaw  120  and lower jaw  140  in a hinged manner at the distal end of end effector  100 . Blade/knife assembly  170 , which includes I-beam or I-shaped knife  172  (see also  FIG.  9   ) is disposed within lower jaw  140 . Master link  180  connects upper jaw  120  and lower jaw  140  at the proximal end of end effector  100  in a hinged manner using master pin  182 , which is positioned in a sliding manner within master link slot  184 . End effector  100  is attached to elongated support tube  190 , which is connected to handle  200  (see also  FIGS.  5  and  6   ). Handle  200  includes various mechanical aspects that actuate end effector  100  and knife  172 . A region of concern or “no tissue zone”  160  can be any area or space into which tissue may unwantedly migrate during surgical procedures such as laparoscopic bariatric surgery. No tissue zone  160  may be located at the proximal end of the end effector, for example, but may be any area where tissue migration is problematic. 
       FIG.  2    depicts an example labeling solution to the tissue migration concern.  FIG.  2    depicts the surgical stapler of  FIG.  1 B , wherein a physical label has been placed on the lower jaw of end effector  100  indicating that “no tissue” is to be situated within the labeled region, which is no tissue zone  160 ). “No tissue” graphics may also be included on top of anvil assembly  122 , on upper jaw  120 , on the side of cartridge assembly  142 , on lower jaw  140 , or on any other surface of end effector  100  to alert the user of the risk. Labeling may be affixed to end effector  100  using adhesive, or by screen printing, laser etching, or the like, and may include additional or alternate phrases, as wells as various fonts, colors, and graphics intended to draw the attention of a user to the no tissue zone. 
       FIGS.  3 - 8    depict various implementations of a tissue-blocking shield placed around the jaws of end effector  100  for the purpose preventing tissue from migrating into region  160  while still permitting the jaws of end effector  100  to open.  FIG.  3    depicts the stapler of  FIG.  1 B , wherein the jaws of end effector  100  are shown in a closed position and flexible tissue-blocking sheath  300  has been partially wrapped around upper and lower jaws  120  and  140  of end effector  100 .  FIG.  4    depicts the stapler of  FIG.  1 B , where the jaws of end effector  100  are shown in an open position and flexible tissue-blocking elastomeric sheath  300  has been partially wrapped around upper and lower jaws  120  and  140  of end effector  100 . Sheath lock  302  is included in this implementation for locking cape  300  on end effector  100 . Sheath lock  302  may be an overmolded plastic component located on either side of lower jaw  140 . Sheath lock  302  may be affixed to lower jaw  140  with a screw or other positive fixation device such as a rivet, pin, orbital rivet, or heat stake. The proximal end of sheath lock  302  is affixed to lower jaw  140  by engaging an interlocking feature in support tube  190 . Sheath lock  302  may incorporate a jaw lock component or may engage with a jaw lock to constrain the sheath lock  FIG.  5    depicts the end effector of  FIG.  1 B , where the jaws of end effector  100  are shown in a closed position and elastomeric tissue-blocking sleeve  310  has been circumferentially wrapped around upper and lower jaws  120  and  140  of end effector  100 .  FIG.  6    depicts the end effector of  FIG.  1 B , where the jaws of end effector  100  are shown in an open position and elastomeric tissue-blocking sleeve  310  has been circumferentially wrapped around upper and lower jaws  120  and  140  of end effector  100 .  FIG.  7    depicts the end effector of  FIG.  1 B , wherein the jaws of end effector  100  are shown in an open position and flexible, braided mesh barrier  320  has been circumferentially wrapped around upper and lower jaws  120  and  140  of end effector  100 .  FIG.  8    depicts upper jaw  120  of the end effector of  FIG.  1 B , wherein recessed region  322  has been formed therein for accommodating a flexible cape or sleeve. 
     The sheath and sleeve described above may be made from a variety of elastic materials including silicone, urethane, or the like, or may be geometrically flexible such as the braided implementation of  FIG.  7   . The implementation shown in  FIG.  7    may include bands placed on both ends of the sleeve to prevent the sleeve from fraying. Alternately, both ends of the sleeve may be overmolded with an elastomeric material to prevent the sleeve from fraying. The sheath and sleeve may be lubricated to minimize drag force when inserting the stapling instrument into a trocar. Lubrication may be achieved by altering the surface finish of the sheath, adding a lubricant to the sheath such as a silicone grease, polytetrafluoroethylene (PTFE) solids or the like, or by doping the sheath material with a lubricant. Adding a stainless steel or plastic spine (not shown) to the top of the sheath may also reduce drag force. The spine may be over-molded to the sheath or rigidly attached to anvil frame  124  by the use of screws or snaps, or by welding, gluing, or other process. Sheath lock  302  member fixes sheath  300  to end effector  100  and may be made of a metal such as stainless steel, or a plastic such as nylon, and may be attached to cartridge frame  144  by a screws, snaps, or other devices. Sheath  300  and sheath lock  302  may be separate components or a single component installed on end effector  100  by over-molding sheath  300  to sheath lock  302 . Sheath lock  302  may incorporate a jaw lock component or may engage with a jaw lock to constrain the sheath lock. The previously described no tissue zone labeling may be included on some or all variants of sheath  300 . 
       FIG.  9    depicts end effector  100  in a closed position where tissue cutting knife  172 , also referred to as an I-beam or I-shaped blade, is visible near distal pin  156 . Regarding  FIG.  9   , one implementation of the disclosed technology provides a reversing knife solution to the previously discussed tissue migration concern. This approach eliminates the problem of transecting unstapled tissue by stopping knife  172  before it reaches the no tissue zone at the proximal end of the end effector  100 . After transecting only stapled portions of tissue, the knife  172  can be distally to its starting position, tangent to distal pin  156 , as shown in  FIG.  9   . Using this method, knife  172  will not cut tissue without also firing staples along the cut line. 
     The solution reversing the knife  172 , as described above, may be accomplished using software included with commercially available stapling instruments such as, for example, the TITAN® SGS23R “Standard Power Unit” (SPU) software. Once a knife band (see U.S. Pat. No. 10,687,814) activates a limit switch at the proximal limit of firing, such as at the proximal end of the end effector  100 , the SPU software can reverse the polarity of the firing motor, to reverse the direction of the knife band. To stop the I-Beam from striking the distal pin  156  when reversing the knife, the SPU can actively monitor the presence of the I-Beam at the distal tip of the end effector  100 . A distal limit switch may be attached to end effector  100 , stopping the firing motor when the I-Beam has reached its distal position (see  FIG.  9   ). The distal limit switch may be a digital switch that operates in a binary on/off nature depending on whether the I-Beam is at its distal position or not, or an analog sensor that provides a range of values depending on where the I-Beam is located in the firing stroke. If the switch is binary, it may be an off-the-shelf (OTS) single pole single throw (SPST) limit switch that is mounted to a printed circuit board (PCB), a stand-alone OTS limit switch wired back to the SPU by way of a power cable, or a custom limit switch consisting of a movable component that electrically connects (normally open, “NO”) or disconnects (normally closed, “NC”), two terminals connected to the SPU. In one implementation, the I-Beam and distal pin  156  cooperate to complete an electric connection and act as a binary switch. If the switch is analog, it may be an OTS analog sensor that is mounted to a PCB or a stand-alone OTS limit switch wired back to the SPU by way of a power cable such as a proximity sensor, ultrasonic sensor, time of light sensor (ToF), laser sensor, light detecting and ranging (LIDAR) sensor, or the like, or a custom analog sensor connected to the SPU. Some implementations include various indicators such as, for example, audible, visual, or tactile indicators, or combinations thereof, that are triggered by the software and sensors when the presence of tissue is detected within no tissue zone  160 . 
     In some implementations, a rotary encoder is included with the firing motor to stop the I-Beam from crashing into distal pin  156  when reversing knife  172 , to provide closed-loop feedback of the motor&#39;s rotary position. With an encoder, the SPU software monitors the number of motor turns required to activate the proximal firing limit switch and repeats the same number of motor turns to return the knife band to its starting position. Suitable motor encoder technology may be mechanical, optical, or magnetic (hall-effect) to track the rotation of the motor shaft. The SPU may also monitor real-time electrical motor current in amperes to compare to preset current limits when using a device such as the TITAN® SGS23R. The current limits may mitigate damage to the device when in use. The SPU may further monitor the firing motor current when reversing the knife, monitoring for a current spike above a preset threshold to determine when the I-Beam contacts distal pin  156 . System software may, for example, only monitor for the current spike at a percentage of the return sequence by means of time or using an encoder as described above. In a similar manner, in an alternate implementation, the SPU monitors the closure motor current for the presence of tissue in the no tissue zone. Tissue in the no tissue zone induces a spike in current on the closure motor within a fixed window of time or closure stroke. Identifying this minimum current spike allows the SPU to detect tissue in the no tissue zone and warn the user of imminent tissue damage and/or prevent the user from firing the device. 
       FIG.  10    depicts another implementation for stopping the I-Beam from striking distal pin  156  when reversing knife  172 , wherein the threads on firing lead screw  402  stop distally, passively limiting the reverse travel of firing nut  406 . In this implementation, firing nut  406  exhausts the threads on firing lead screw  402  and slips on the threads as firing lead screw  402  continues to turn to drive firing nut  406  distally. Fixed firing screw compression spring  410  applies a load proximally on firing nut  406  and allows firing nut  406  to reengage with firing lead screw  402  when firing lead screw  402  rotates to drive firing nut  406  proximally. Fixed firing lead screw  402  is constrained laterally by firing bushing  412  and the threads of firing lead screw  402 , limited by its inner diameter (ID) being less than the major diameter of the threads of firing lead screw  402 . 
       FIG.  11    depicts another implementation for stopping the I-Beam from crashing into distal pin  156  when reversing knife  172 , wherein the threads on firing screw  402  stop distally, passively limiting the reverse travel of firing nut  406 , but where firing screw compression spring  410  is mobile rather than fixed. In this implementation, mobile firing screw compression spring  410  is constrained by nut plate  414  and firing nut  406 , and spring  410  travels along the threaded and unthreaded portion of firing lead screw  402  as firing nut  406  and nut plate  414  travel. Nut plate  414  is unthreaded, unlike firing nut  406 , and slides along the threaded and unthreaded portion of firing lead screw  402  like mobile firing screw compression spring  410 . When firing nut  406  exhausts the threads on firing lead screw  402 , it will slip on the threads as firing lead screw  402  continues to turn to drive firing nut  406  distally. Unlike the previous implementation, this variant anticipates a crash of the I-Beam and distal pin  156 , but mobile firing screw compression spring  410  provides a compliant power transfer from firing nut  406  and knife band  408  when firing nut  406  is driven distally. 
       FIG.  12    depicts end effector  100 , wherein the jaws of end effector  100  are shown in a closed position and wherein tissue-blocking anvil cap  330  has been formed or placed on upper jaw  120  of end effector  100 .  FIG.  13    depicts end effector  100 , wherein the jaws of end effector  100  are shown in an open position and wherein tissue-blocking anvil cap  330  has been formed or placed on upper jaw  120  of end effector  100 . In this implementation, anvil cap  300  may be formed on anvil frame  124  or may be rigidly attached thereto as a separate structure using welding, adhesives, or attachment hardware such as bolts or screws. Anvil cap  330  cooperates with second proximal tissue stop  154  on cartridge frame  144  to create a shield for preventing tissue from entering no tissue zone  160 . When upper and lower jaws  120  and  140  are closed, anvil cap  330  may not protrude past the bottom edge of cartridge frame  144 . When upper and lower jaws  120  and  140  are open, anvil cap  330  can shield the no tissue zone. 
       FIG.  14    depicts an implementation that prevents the transection of unstapled tissue. This implementation is referred to as the “cantilever beam” and includes disengaging I-beam knife  172 . In  FIG.  14   , I-Beam knife  172  is shown as a cantilevered beam knife. In this implementation, the feature responsible for clamping down anvil plate  126  is set in front of knife  172 , which transects the tissue. In this way, knife  172  cannot cut tissue without the tissue already being fastened with staples because the cantilever beam escapes anvil assembly  122  before knife  172 , allowing end effector jaws  120  and  140  to be opened when knife  172  is in the proximal position. In this implementation, if tissue is present in the no tissue zone, the tissue may be stapled but will not be cut. 
       FIG.  15    depicts an implementation that utilizes a reversing knife approach to preventing the transection of unstapled tissue through the inclusion of a secondary thread on the primary firing screw. Formed along most of the length of firing screw  500  is a primary coarse thread  502  that provides enough travel to drive firing nut  504  from the distal end of end effector  100  to the proximal end thereof, cutting and firing staples longitudinally along the end effector. On the proximal end of firing screw  500  secondary thread segment  506  is formed having thread  506 , which is finer that primary thread  502 . The pitch and travel of secondary thread  506  are proportional to primary thread  502 . Firing nut  504  rides along primary coarse thread  502  only and limit switch nut  508  rides along secondary fine thread  506  only. When firing screw  500  is turning, firing nut  504  and limit switch nut  508  move in the same direction but at different linear velocities and therefore travel different distances. Limit switch nut  508  will travel in between two limit switches, distal limit switch  510  and proximal limit switch  512  (see  FIG.  15   ). Before end effector  100  is fired, firing nut  504  will be at the distal end of the end effector and limit switch nut  508  will be activating distal limit switch  510 . After end effector  100  has fired, firing nut  504  will be at the proximal end of the end effector and limit switch nut  508  will be activating proximal limit switch  512 . 
       FIG.  16    depicts an implementation that utilizes a reversing knife approach to preventing the transection of unstapled tissue through the inclusion of a secondary fine thread on an auxiliary firing screw. This implementation is similar to what shown in  FIG.  15   ; however, auxiliary firing screw  514  obtains its rotation from firing screw  502  by way of meshed gears  516  and  518 . In either implementation, primary firing screw  500  or auxiliary firing screw  514  may be any combination of left-handed or right-handed threads. 
       FIG.  17    depicts an implementation of end effector  100 , wherein the jaws of end effector  100  are shown in an open position and where tissue-blocking elastomeric band  348  has been mounted on attachment screw  340  on upper jaw  120  and attachment screw  342  on lower jaw  140 .  FIG.  18    depicts end effector  100 , where the jaws of end effector  100  are shown in an open position and where tissue-blocking elastomeric band  348  has been mounted on attachment screws  340  and  344  on upper jaw  120  and attachment screws  342  and  346  on lower jaw  140  in a crossed configuration.  FIG.  19    depicts end effector  100 , wherein the jaws of end effector  100  are shown in an open position and where tissue-blocking elastomeric band  348  has been mounted on attachment screw  340  on upper jaw  120  and attachment screws  342  and  344  on lower jaw  140  in a triangular configuration. Elastic band  348  may be silicone, urethane, or similar material, and may be a full loop or an elastic string. In alternate implementations, the attachments screws are replaced with rivets, glued posts, welded posts, or stamped or molded features formed on upper and lower jaws  120  and  140 . 
       FIG.  20    depicts an implementation of end effector  100 , where the jaws of end effector  100  are shown in an open position and wherein tissue-blocking rotating post  350  has been positioned between upper and lower jaws  120  and  140  of end effector  100 . In the implementation shown in  FIG.  20   , attachment point  342  includes a torsional spring that biases post  350  in a vertical position. When jaws  120  and  140  are open, the torsional spring rotates post  350  upward, perpendicular to cartridge frame  144 . When jaws  120  and  140  close, a moment is applied to post attachment point  342  by way of anvil frame  124  on the end of post  350  that counteracts the force on the torsional spring and rotates post  350  counterclockwise or clockwise until post  350  is parallel, or nearly parallel, to cartridge frame  144 .  FIG.  20    also depicts an alternate configuration, wherein the end of post  350  opposite attachment point  342  is constrained by cam profile  352  on anvil frame  124 , and wherein the end of post  350  opposite attachment point  342  acts as cam follower  354 . As jaws  120  and  140  open, cam profile  352  forces cam follower  354  into a vertical position, perpendicular to cartridge frame  144 . As jaws  120  and  140  close, cam profile  352  forces cam follower  354  into a horizontal position, parallel, or nearly parallel, to cartridge frame  144 . This implementation may include any combination of a torsional spring, and cam profile and cam follower. 
       FIG.  21    depicts an implementation of end effector  100 , wherein the jaws of end effector  100  are shown in an open position and wherein tissue-blocking telescoping post  360  has been positioned between upper and lower jaws  120  and  140  of end effector  100 . In the implementation shown in  FIG.  21   , post  360  does not rotate but telescopically translates in a vertical manner. Telescoping post  360  may be biased upward using a compression spring that is compressed when jaws  120  and  140  close. When jaws  120  and  140  open, the compression spring forces the inner telescopic members of post  360  upward. A structure such as, for example, a ball and socket joint, may be included on anvil frame  124  for constraining the lateral movement of telescoping post  360  and providing a surface for compressing post  360 . This structure or feature may be attached to anvil frame  124  using screws, rivets, glue, welding, or by using features stamped or molded into anvil frame  124 . 
       FIG.  22    depicts an implementation of end effector  100 , where the jaws of end effector  100  are shown in an open position and wherein tissue-blocking curved linkage  362  has been positioned between upper and lower jaws  120  and  140  of end effector  100 . In the implementation shown in  FIG.  22   , curved linkage  362  is used to clamp upper jaw  120  to lower jaw  140 . Curved linkage  362  is pinned in anvil frame  124  wherein it rotates freely. Curved linkage  362  pivots or slides near cartridge  150  as it is pushed or pulled from inside support tube  190  to open or close jaws  120  and  140 . Curved linkage  362  is present inside the no tissue zone, thereby shielding tissue from entering it, and is bowed to allow adjacent tissue in jaws  120  and  140  to be pushed out of the no tissue zone. 
       FIG.  23    depicts an implementation of end effector  100 , where the jaws of end effector  100  are shown in an open position and wherein tissue-blocking passive curved linkage  362  has been positioned between upper and lower jaws  120  and  140  of end effector  100 . In the implementation shown in  FIG.  23   , curved linkage  364  includes a passive band that cooperates with a separate linkage. The band is pinned on upper jaw  120  at  340  and pivots in lower jaw  140  at pivot point  342 . The passive band does not mechanically clamp jaws  120  and  140  together but shields the no tissue zone. The passive band is pulled underneath the separate link when jaws  120  and  140  are closed. When jaws  120  and  140  are opened, the passive band is bowed and present in the no tissue zone. 
       FIG.  24    depicts an implementation of end effector  100 , where the jaws of end effector  100  are shown in an open position and where a tissue-blocking pivoting double linkage  365  has been positioned between upper and lower jaws  120  and  140  of end effector  100 . Double linkage  365 , which has an additional degree of freedom compared to other disclosed implementations, includes first link  366  connected to second link  370  at pivot point  370 . When jaws  120  and  140  are closing, pivot point  370  pushes tissue out of the no tissue zone, if present, and double linkage  365  then folds into cartridge frame  144 . When jaws  120  and  140  are opening, the double linkage unfolds and becomes a rigid member that shields the no tissue zone. Double linkage  365  is connected to anvil frame  124  in a hinged manner at attachment point  340 . 
       FIG.  25    depicts an implementation of end effector  100 , wherein the jaws of end effector  100  are shown in an open position and where a tissue-blocking sacrificial cut band  372  has been positioned between upper and lower jaws  120  and  140  of end effector  100 . In the implementation shown in  FIG.  25   , sacrificial cut band  372  occupies the entire distance between upper and lower jaws  120  and  140  and the entire width of both cartridge frame  144  and anvil frame  124 . Sacrificial cut band  372  is cut or destroyed when I-Beam knife  172  fires through the band at the end of the firing stroke of knife  172 . The sacrificial band is typically made from a soft material, such as silicone, urethane, or any other suitable material, so that knife  172  can effectively fire through the band. The band shields tissue from the no tissue zone while also allowing the jaws of the end effector device to close. 
       FIG.  26    depicts an implementation of end effector  100 , where the jaws of end effector  100  are shown in an open position and wherein a tissue-blocking split band  373  has been positioned between upper and lower jaws  120  and  140  of end effector  100 . In the implementation shown in  FIG.  26   , split band  373  includes first band portion  374  and separate second band portion  376  for allowing I-Beam knife  172  to pass through the separate band portions when fired. Split band  373  may be attached to cartridge frame  144  or cartridge  150  on lower jaw  140  and to anvil frame  124  on upper jaw  120 . Split band  373  shields tissue from the no tissue zone while also allowing the jaws of the end effector device to close. 
       FIG.  27    depicts an implementation of end effector  100 , wherein the jaws of end effector  100  are shown in an open position and where tissue-blocking compliant sacrificial foam block  380  has been positioned between upper and lower jaws  120  and  140  of end effector  100 .  FIG.  28    depicts an implementation of end effector  100 , where the jaws of end effector  100  are shown in an open position and wherein tissue-blocking compliant sacrificial balloon  382  has been positioned between upper and lower jaws  120  and  140  of end effector  100 . Both compliant sacrificial foam block  380  and compliant sacrificial balloon  382  can permit I-beam knife  172  to pass through the area of end effector  100  occupied by these elements or features. Compliant sacrificial foam block  380  may be attached to anvil frame  124 , cartridge frame  144 , cartridge  150 , or may be simply constrained by the components surrounding the no tissue zone. The block is compliant, in an example, and may be fabricated from an open cell foam or closed cell foam, and allows upper and lower jaws  120  and  140  to clamp together. The block can include a specific density that allows I-Beam knife  172  to fire through it when compressed. The compliant block may be sacrificial and may be destroyed from the firing sequence of end effector  100 . Compliant sacrificial balloon  382  can be a gas filled compliant balloon, rather than a block, that allows upper and lower jaws  120  and  140  to clamp together without bursting and may be destroyed from the firing sequence of end effector  100 . The compliant balloon may be attached to anvil frame  124 , cartridge frame  144 , cartridge  150 , or may be simply constrained by the components surrounding the no tissue zone. 
       FIG.  29    depicts an implementation of end effector  100 , wherein the jaws of end effector  100  are shown in an open position and wherein tissue-blocking zero clearance block  383  having top portion  384  and bottom portion  386  has been positioned between upper and lower jaws  120  and  140  of end effector  100 . In the implementation shown in  FIG.  29   , zero clearance block  383  is neither compliant nor sacrificial, but rather is a rigid tapered block attached to both upper and lower jaws  120  and  140  that pushes clamped tissue out of the no tissue zone. Both top portion  384  and bottom portion  386  can include a centrally placed channel or gap that permits I-beam knife  172  to travel through each portion. Rigid tapered block  383  may be a structure integrated into anvil frame  124  and cartridge frame  144  (or cartridge  150 ) or it may be a separate component fabricated from rigid plastic such as nylon or from metal such as stainless steel. If the rigid tapered block is a separate component, it may be attached to upper and lower jaws  120  and  140  by gluing, welding, snap features, or with hardware such as bolts or screws. The rigid block may produce zero clearance in the no tissue zone when the jaws of end effector  100  are closed. 
       FIGS.  30  and  31    depict alternate devices and methods of shielding the no tissue zone by using an accordion-like shield that can “fan out” when the jaws of the end effector are open and “fold in” when the jaws of the end effector are closed. Example devices can be attached to upper and lower jaws  120  and  140  to give the shield two or more anchor points when pulled apart. These accordion-like devices may be fabricated from a rigid or flexible metal or plastic or any other suitable material.  FIG.  30    depicts an implementation of end effector  100 , where the jaws of end effector  100  are shown in an open position and where accordion shield  388  has been positioned between upper and lower jaws  120  and  140  of end effector  100 . Accordion shield  388  extends along each side of the no tissue zone and maintains its overall footprint when extended. In this implementation, I-Beam knife  172  can travel in-between the two sides of the accordion shield.  FIG.  31    depicts an implementation of end effector  100 , where the jaws of end effector  100  are shown in an open position and where fan shield  390  has been positioned between upper and lower jaws  120  and  140  of end effector  100 . In the implementation shown in  FIG.  31   , fan shield  390  fans out distally when extended and extends in a semi-circular pattern from a central axis inside the no tissue zone. Fan shield  390  may be sacrificial, destroyed by knife  172  during the firing sequence of end effector  100 , or it may be split into two separate fans to allow knife  172  to pass through the no tissue zone. 
       FIG.  32    depicts an implementation that utilizes a disengaging I-beam knife approach (normal orientation) to prevent the transection of unstapled tissue and  FIG.  33    depicts an implementation that utilizes a disengaging I-beam knife approach (disengage orientation) to prevent the transection of unstapled tissue. In the implementations shown in  FIGS.  32  and  33   , I-beam top shelf  174  can be disengaged from anvil plate  126  at proximal tissue stop  154 . In these implementations, knife  172  stops at proximal tissue stop  154  or in front of the no tissue zone, but I-beam top shelf  174  may continue on a separate linear travel mechanism until it clears anvil plate  126  as shown in  FIG.  33   . Alternately, I-beam top shelf  174  may become free from I-Beam  170  by means of a mechanical fuse or the like, thereby allowing upper jaw  120  to open relative to lower jaw  140 . In a similar fashion, I-beam bottom shelf  176  may be disengaged. I-beam top shelf  174  may be disengaged from anvil frame  124  and I-beam bottom shelf  176  may become disengaged from cartridge frame  144  by a trap door or a moving door mechanism, allowing the end effector jaws to open without being constrained by the top and/or bottom shelf 
       FIG.  34    depicts an implementation that utilizes an external device referred to as an introducer sheath to shield the no tissue zone. In the implementation shown in  FIG.  34   , introducer sheath  600  is not fixed to end effector  100 , but slides longitudinally along the stapling instrument and may be concentric to the end effector  100 . Introducer sheath  600  may cooperate with a trocar, a shielding sheath, or another device. Shielding sheath  602  may be flexible in the no tissue zone location, allowing the end effector jaws to open, close, and fit through a trocar while still shielding the no tissue zone. 
     All literature and similar material cited in this application, including, but not limited to, patents, patent applications, articles, books, treatises, and web pages, regardless of the format of such literature and similar materials, are expressly incorporated by reference in their entirety. Should one or more of the incorporated references and similar materials differs from or contradicts this application, including but not limited to defined terms, term usage, described techniques, or the like, this application controls. 
     As previously stated and as used herein, the singular forms “a,” “an,” and “the” refer to both the singular as well as plural, unless the context clearly indicates otherwise. The term “comprising” as used herein is synonymous with “including,” “containing,” or “characterized by,” and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. Although many methods and materials similar or equivalent to those described herein can be used, particular suitable methods and materials are described herein. Unless context indicates otherwise, the recitations of numerical ranges by endpoints include all numbers subsumed within that range. Furthermore, references to “one implementation” are not intended to be interpreted as excluding the existence of additional implementations that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, implementations “comprising” or “having” an element or a plurality of elements having a particular property may include additional elements whether or not they have that property. 
     The terms “substantially” and “about” used throughout this specification are used to describe and account for small fluctuations, such as due to variations in processing. For example, these terms can refer to less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%, and/or 0%. 
     Underlined and/or italicized headings and subheadings are used for convenience only, do not limit the disclosed subject matter, and are not referred to in connection with the interpretation of the description of the disclosed subject matter. All structural and functional equivalents to the elements of the various implementations described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and intended to be encompassed by the disclosed subject matter. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the above description. 
     There may be many alternate ways to implement the disclosed inventive subject matter. Various functions and elements described herein may be partitioned differently from those shown without departing from the scope of the disclosed inventive subject matter. Generic principles defined herein may be applied to other implementations. Different numbers of a given module or unit may be employed, a different type or types of a given module or unit may be employed, a given module or unit may be added, or a given module or unit may be omitted. 
     It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail herein (provided such concepts are not mutually inconsistent) are contemplated as being part of the disclosed inventive subject matter. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. While the disclosed inventive subject matter has been illustrated by the description of example implementations, and while the example implementations have been described in certain detail, there is no intention to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the disclosed inventive subject matter in its broader aspects is not limited to any of the specific details, representative devices and methods, and/or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept.