Patent Publication Number: US-2019175171-A1

Title: Chisel cut staples for use in surgical staplers and a method for manufacturing surgical staples

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 62/596,353, filed Dec. 8, 2017, the entire disclosure of which is incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to surgical staples and, more specifically, to surgical staples having staple legs with chisel cut tips and methods for manufacturing such surgical staples. 
     2. Discussion of Related Art 
     Surgical stapling apparatus are employed by surgeons to sequentially or simultaneously apply one or more rows of staples to body tissue for the purpose of joining segments of body tissue together. Typically, a staple has a backspan and a leg extending away from each end of the backspan in a substantially orthogonal direction. Each staple leg has a free end spaced from the backspan. The free end of each leg has a tip which is sharpened to penetrate tissue and guide the respective leg through the tissue. 
     When the stapler is actuated, or “fired”, a drive member ejects or pushes staples from a staple cartridge towards an anvil. As the staples are pushed towards the anvil, the tips of each staple penetrate tissue and guide the legs through the tissue. As the tips of the staples contact the anvil, the tips are deflected such that the legs of the staples are formed into a desired shape. 
     In some surgical procedures, the staple legs are malformed when the tips of the staple are deflected by the anvil. This can be a result of the tips veering off target as the tips pass through tissue and/or when the tips contact the anvil. 
     Accordingly, there is a continuing need in the surgical arts to reduce the number of malformed staples during a surgical procedure. 
     SUMMARY 
     This disclosure generally relates to staples that have symmetrical tips which improve performance of staples during a surgical procedure. Specifically, the symmetrical tips improve tracking of the staple through tissue and improve the formation of staples when the tips contact an anvil. 
     This disclosure also relates to a method of forming staples with symmetrical tips. Specifically, this disclosure relates to a process of sharpening the tips of a staple with a “chisel-cut” such that the tips of the staple are sharpened in a symmetrical manner. 
     In an aspect of the present disclosure, a surgical staple includes first and second legs that are interconnected by a backspan. Each of the first and second legs defines a longitudinal leg axis and extends from the backspan along the leg axis to a tip. The tip is sharpened such that the tip is symmetrical about a longitudinal axial leg plane which includes the leg axis. 
     In aspects, the tip includes a face that defines an angle with the leg axis. The angle may be in a range of about 15 0   to about 60°. The face may have a substantially elliptical shape. The major axis of the face may be disposed at an angle with the leg axis and a minor axis of the face may be perpendicular to the leg axis. The minor axis of the face may be perpendicular to a longitudinal axis of the backspan. 
     In some aspects, the face includes a leading edge that is parallel to a minor axis of the face and is intersected by a major axis of the face. The leading edge may be configured to steer the tip through tissue. 
     In another aspect of the present disclosure, a method of manufacturing a surgical staple includes sharpening a tip of a leg of the surgical staple such that the tip is symmetrical about a longitudinal axial leg plane that includes a longitudinal leg axis of the leg. 
     In aspects, sharpening the tip of the leg includes passing a die through the tip to form a planar face on the tip that has a substantially elliptical shape. Passing the die through the tip includes moving the die in a direction along a major axis of the face. Moving the die in a direction along the major axis of the face may include moving the die along the face from a trailing edge of the face towards a leading edge of the face. Passing the die through the tip may include moving the die in a direction that defines an angle with the leg axis in a range of about 15° to about 60°. 
     In another aspect of the present disclosure, a surgical stapler includes a handle and a loading unit. The loading unit is releasably coupled to the handle. The loading unit includes an end effector having a staple cartridge that houses a plurality of staples. Each staple has first and second legs that are interconnected by a backspan. Each of the first and second legs defines a longitudinal leg axis and extends from the backspan along the leg axis to a tip. The tip is sharpened such that the tip is symmetrical about a longitudinal axial leg plane that includes the leg axis. 
     In aspects, the tip includes a face that defines an angle with the leg axis. The angle may be in a range of about 15° to about 60°. 
     In some aspects, the end effector assembly is selected from the group consisting of a linear end effector assembly, a circular end effector assembly, a transverse end effector assembly, and a curved end effector assembly. The handle may be configured to manually actuate the end effector assembly. The handle may be configured to electromechanically actuate the end effector assembly. 
     Further, to the extent consistent, any of the aspects described herein may be used in conjunction with any or all of the other aspects described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of the present staples are described hereinbelow with reference to the drawings, which are incorporated in and constitute a part of this specification, wherein: 
         FIG. 1  is a perspective view of a manually actuated circular stapler useful in applying staples provided in accordance with the present disclosure to tissue; 
         FIG. 2  is an enlarged perspective view of an end effector assembly of the circular stapler of  FIG. 1  with an assembly of the end effector assembly separated from a loading unit of the end effector assembly; 
         FIG. 3  is a perspective view, with parts separated, of a portion of the loading unit shown in  FIG. 2 ; 
         FIG. 4  is a perspective view of a manually actuated linear stapler useful in applying staples provided in accordance with the present disclosure to tissue; 
         FIG. 5  is a perspective view, with parts separated, of the end effector assembly of the linear stapler of  FIG. 4 ; 
         FIG. 6  is a perspective view of an electromechanical surgical system and a plurality of loading units that are selectively attachable to a handle of the surgical system useful in applying staples provided in accordance with the present disclosure to tissue; 
         FIG. 7  is a perspective view of a prior art staple and a die for forming tips of the staple; 
         FIG. 8  is an enlarged view of the indicated area of detail of  FIG. 8 ; 
         FIG. 9  is a side view of a tip of the prior art staple of  FIG. 7 ; 
         FIG. 10  is a perspective view of the tip of the prior art staple of  FIG. 7 ; 
         FIG. 11  is a perspective view of a staple and a die for forming tips of staples provided in accordance with the present disclosure; 
         FIG. 12  is an enlarged view of the indicated area of detail of  FIG. 11 ; 
         FIG. 13  is a side view of a tip of the staple of  FIG. 11 ; 
         FIG. 14  is a perspective view of the tip of the staple of  FIG. 11 ; and 
         FIG. 15  is a plan view of a tissue contacting surface of an anvil of the circular stapler instrument of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present staples are now described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein, the term “clinician” refers to a doctor, a nurse, or any other care provider and may include support personnel. Throughout this description, the term “proximal” refers to the portion of the device or component thereof that is closest to the clinician and the term “distal” refers to the portion of the device or component thereof that is farthest from the clinician. 
     With reference to  FIG. 1 , a circular surgical stapler  100  useful in applying staples in accordance with the present disclosure includes a handle assembly  110 , an elongate portion  120  extending distally from the handle assembly  110 , and an end effector  130  secured to a distal portion of the elongate portion  120 . The end effector  130  includes a loading unit  140  and an anvil  160 . The handle assembly  110  has a movable handle  112  and a fixed handle  114 . The movable handle  112  is movable towards the fixed handle  114  to actuate or fire the loading unit  130 . For a detailed description of a similar circular surgical stapler, reference can be made to U.S. Pat. No. 8,789,737 (“the &#39;737 Patent”), the entire contents of which are hereby incorporated by reference. 
     Referring to  FIGS. 2 and 3 , the loading unit  140  includes a staple cartridge  150  pusher driver  152 , an annular ring of pushers  154 , and staples  10  supported within the staple cartridge  150 . The pusher driver  152  is positioned in abutting relation to a proximal end of the pushers  154 . The staples  10  are supported within the staple cartridge  150  and are arranged in one or more rings with a pusher  154  of the annular ring of pushers  154  associated with one or more of each of the staples  10 . The staple cartridge  150  defines a plurality of openings  157  that receive with the staples  10  and the pushers  154  such that as the loading unit  130  is fired, the pushers  154  eject or push the staples  10  towards the anvil  160  through the openings  157 . 
     The anvil  160  includes a shaft  162  that passes through the loading unit  140  and is secured to the elongate portion  120  ( FIG. 1 ) such that the handle assembly  110  draws the anvil assembly  160  towards the staple cartridge  150  when the handle assembly  110  is actuated to fire the staples  10  such as described in more detail in the &#39;737 Patent. The anvil  160  also defines staple pockets  164  on a tissue contacting surface of the anvil  160  that is opposed to the staple cartridge  150 . Each staple pocket  164  is aligned with a respective staple  10  when the anvil  160  is secured to the elongate portion  120  such that when the staples  10  are pushed towards the anvil  160 , each staple  10  is received within a respective staple pocket  164  such that the staple  10  is formed in tissue disposed between the loading unit  140  and the anvil assembly  160 . 
     Referring to  FIG. 4 , a linear surgical stapler  200  useful in applying staples in accordance with the present disclosure includes a handle assembly  210 , an elongate portion  220  extending distally from the handle assembly  210 , and a loading unit  230  secured to a distal portion of the elongate portion  220 . The loading unit  230  includes an end effector assembly  240 . The handle assembly  210  has a movable handle  212  and a fixed handle  214 . In embodiment, the movable handle  212  is movable towards the fixed handle  214  to move the end effector assembly  240  towards a clamped position and actuate or fire end effector assembly  240  of the loading unit  230 . For a detailed description of an exemplary linear surgical stapler, reference can be made to U.S. Patent Publication No. 2015/0297216, the entire contents of which are hereby incorporated by reference. Alternatively, the stapler  200  may include separate handles for effecting clamping and firing of the stapler  200 . 
     Referring to  FIG. 5 , the end effector assembly  240  includes a first jaw  250  defining a channel  252 , a staple cartridge  260  releasably received within the channel  252 , and a second jaw  270  having an anvil  272  defining staple pockets  274 . The staple cartridge  250  includes a body  262 , pushers  264 , and staples  10 . In embodiments, the staples  10  are arranged in one or more rows with one of the pushers  264  associated with one or more of the staples  10 . The body  262  defines a plurality of openings  262  that receive the staples  10  and the pushers  264  such that as the end effector assembly  240  is fired, the pushers  264  eject or push the staples  10  through the openings  262  towards the anvil  272 . As the each staple  10  is received within a respective staple pocket  274  of the anvil  272 , the staple  10  is formed in tissue disposed between the staple cartridge  260  and the anvil  272 . 
     Referring to  FIG. 6 , an electromechanical surgical instrument or system  300  useful in applying staples in accordance with the present disclosure includes a powered handle  310 , an adapter  320 , and one or more loading units  330 ,  430 ,  530 ,  630  which may be selectively attached to the adapter  320 . The loading unit may include, but is not limited to a linear loading unit  330 , a circular loading unit  430 , a transverse loading unit  530 , or a curved loading unit  630 . Each of the loading units  330 ,  430 ,  530 ,  630  includes a staple cartridge  360 ,  460 ,  560 ,  660  having a plurality of staples, e.g., staples  10  ( FIG. 3 ). For a detailed description of an exemplary electromechanical surgical system  300  reference can be made to U.S. Patent Publication No. 2016/0310134, the entire contents of which are hereby incorporated by reference. 
     In addition, it is contemplated that the staples  10 , detailed below, may be used with a loading unit secured to a robotic surgical system such that the robotic surgical system actuates an end effector assembly of the loading unit to clamp tissue and/or to fire staples from the loading unit. An exemplary robotic surgical system is disclosed in U.S. Pat. Nos. 8,828,023 and 9,301,691, the entire contents of which are incorporated herein by reference. 
     The above surgical instrument, e.g., instruments  100 ,  200 , and electromechanical surgical system  300  are meant to be exemplary surgical instruments and systems which may include one or more of the staples  10  detailed below. For example, the staple  10  may also be used with a transverse stapling instrument and/or a manually actuated curved stapling instrument. 
     With reference to  FIGS. 7-10 , a prior art staple  1010  and a method of sharpening legs of the prior art staple  1010  are described in an effort to illustrate the advantages of the method of sharpening the legs of the presently disclosed staples  10 . With particular reference to  FIG. 7 , the staple  1010  includes legs  1020  interconnected by a backspan  1030 . Each leg  1020  defines a longitudinal leg axis L and has a tip  1022  that is spaced apart from the backspan  1030 . Each of the tips  1022  is sharpened to a tapered point that allows the tip  1022  to pierce tissue and to direct the legs  1020  toward an anvil, e.g., anvil  160  ( FIG. 3 ), such that the staple  1010  is properly formed upon actuation of an end effector assembly, e.g., end effector assembly  130  ( FIG. 3 ). 
     Generally, the tip  1022  is formed using a cross-cut process. In a cross-cut process, a die tool  1050  is punched or extended through the tip  1022  of each of the legs  1020  of the staples  1010  in a direction perpendicular to the longitudinal leg axis L of the staple leg  1020  as shown by the arrow CC in  FIG. 7 . Engagement of the die tool  1050  and the tips  1022  of the legs  1020  forms a tapered tip  1022 . 
     With particular reference to  FIGS. 9 and 10 , the cross-cutting process forms a tip  1022  with is not symmetrical in shape about the leg axis L. Specifically, as the die  1050  cuts the tip  1022 , material of the tip  1022  is moved in the direction of travel of the die  1050 , as shown by arrow CC ( FIG. 7 ). This may result in distortion D on the tip  1022 . This distortion D has been shown to steer the staple legs  1020  off target as the tip  1022  travels through tissue, especially in thick tissue indications, and towards an anvil assembly. 
     In several test firings of a circular stapling cartridge with only a single ring of staples  1010  loaded in the circular stapling cartridge, e.g., cartridge  150  ( FIG. 3 ), there was an average of about 5 malformed staples for each firing of the cartridge. These malformed staples may be a result of a distorted tip  1022  steering the leg  1020  of the prior art staple  1010  out of alignment with the anvil assembly as the tip  1022  travels through tissue. 
     Referring now to  FIGS. 11-14 , the staple  10  and a method of sharpening and/or cutting a tip  22  of the legs  20  of the staple  10  is disclosed in accordance with the present disclosure. The staple  10  has legs  20  interconnected by a backspan  30 . Each of the legs  20  defines a longitudinal leg axis L and has a tip  22  spaced apart from the backspan  30 . The tip  22  has a planar face  23  that is generally elliptical in shape with a minor axis  26  that is perpendicular to both the longitudinal leg axis L and a longitudinal axis of the backspan  30  and a major axis  28  defining an angle θ relative to the longitudinal leg axis L in a range of about 15° to about 85°, in embodiments about 35°. The major axis intersects the longitudinal leg axis L between the foci of the planar face  23  and intersects an edge of the planar face  23  at a trailing point  28   a  and a leading point  28   b  with the trailing point  28   a  being closer to the backspan  30  along the longitudinal leg axis L than the leading point  28   b.  The planar face  23  includes a trailing edge  29   a  adjacent the trailing point  28   a  and a leading edge  29   b  adjacent the leading point  28   b.  The leading edge  29   b  may be linear and define an axis that is parallel to the minor axis  26  with the leading point  28   b  being positioned substantially at a center point of the leading edge  29   b.  The leading edge  29  is configured to penetrate tissue and to steer the tip  22  through tissue. 
     To sharpen or cut the tips  22  of the staple  10  by a chisel cut process, the die  50  is moved along the major axis  28  in a direction parallel to a face  23  of the respective tip  22  which is represented by arrow C. As shown, the die  50  is moved along the major axis  28  from the trailing edge  29   a  towards the leading edge  29   b;  however, the die  50  may be moved along the major axis  28  from the leading edge  29   b  towards the trailing edge  29   a.  By sharpening the tip  22  by the chisel cut process, the tip  22  when formed, is symmetrical about a longitudinal axial leg plane which includes the longitudinal leg axis L. 
     Because the tip  22  is symmetrical, the tip  22  is better able to travel straight through tissue without veering off target. By traveling straight through tissue, the accuracy of the tip  22  striking the anvil is increased by an order of magnitude when compared to the prior art staples  1010 . For example, in testing, the tip  22  of the staple legs  20  struck an anvil, e.g., anvil  160  ( FIG. 3 ), within about ±0.001 inches of a target area. In contrast, the tips  1022  of the prior art staples  1010  struck an anvil within about ±0.01 inches of a target area. The increase in accuracy may also improve staple formation, especially in thick tissue procedures, when compared to the prior art staples  1010  where the distortions D of the prior art staples  1010  ( FIGS. 9 and 10 ) may steer the tip  1022 , and thus the leg  1020 , off target which can lead to malformed staples. In testing, the number of malformed staples with the staple  10  was reduced to an average of about 0 malformed staples for each firing of the cartridge when compared to an average of about 5 malformed staples for similar firings of the prior art staples  1010  as detailed above. 
     With reference to  FIG. 15 , strike patterns of the prior art staple  1010  and the staple  10  are shown on the tissue contacting surface  161  of the anvil  160  of the circular stapling instrument  100 . The strike pattern of the prior art staple  1010  is dependent on the direction that the staple  1010  is loaded in the cartridge  150  ( FIG. 3 ). For example, when the staple  1010  is loaded in a first direction with the distortion D ( FIGS. 9 and 10 ) positioned towards the outside of the anvil  160 , the staple  1010  tracks away from the center of the anvil  160  as the tip  1022  of the prior art staple  1010  passes through tissue to form strikes  1060 . Alternatively, when the staple  1010  is loaded in a second direction with the distortion D positioned towards the inside of the anvil  160 , the staple  1010  tracks towards the center of the anvil  160  as the tip  1022  of the prior art staple  1010  passes through tissue to form strikes  1070 . In contrast, when the tip  22  of the staples  10  passes through tissue, the tip  22  stays straight and contacts the tissue contacting surface  161  of the anvil  160  such that the tip  22  tracks directly towards the other tip  22  as shown by the track  60 . By having a predictable and repeatable track, e.g., track  60 , the likelihood of malformed staples is reduced when using staple  10  when compared to staple  1010 . 
     While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Any combination of the above embodiments is also envisioned and is within the scope of the appended claims. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope of the claims appended hereto.