Abstract:
A surgical instrument for being endoscopically or laparoscopically inserted into a surgical site for simultaneous stapling and severing of tissue includes force adjusted spacing between an upper jaw (anvil) and a lower jaw (staple cartridge engaged to an elongate staple channel) so that the height of staple formation corresponds to the thickness of the tissue, yet does not exceed the height range that may be accommodated by the length of the staples. In particular, resilient structures are formed into an E-beam firing bar that includes a cutting surface (knife) that severs tissue between a top pin that engages the anvil and a middle pin and lower foot that engage the lower jaw. The resilience responds to the force exerted by clamped tissue to vary the spacing.

Description:
FIELD OF THE INVENTION 
   The present invention relates in general to surgical stapler instruments 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 stapler instruments and improvements in processes for forming various components of such stapler instruments including adding bolstering material to the severed and stapled tissue. 
   BACKGROUND OF THE INVENTION 
   Endoscopic and laparoscopic surgical instruments are often preferred over traditional open surgical devices since a smaller incision tends to reduce the post-operative recovery time and complications. The use of laparoscopic and endoscopic surgical procedures has been relatively popular and has provided additional incentive to develop the procedures further. In laparoscopic procedures, surgery is performed in the interior of the abdomen through a small incision. Similarly, in endoscopic procedures, surgery is performed in any hollow viscus of the body through narrow endoscopic tubes inserted through small entrance wounds in the skin. 
   Laparoscopic and endoscopic procedures generally require that the surgical region be insufflated. Accordingly, any instrumentation inserted into the body must be sealed to ensure that gases do not enter or exit the body through the incision. Moreover, laparoscopic and endoscopic procedures often require the surgeon to act on organs, tissues and/or vessels far removed from the incision. Thus, instruments used in such procedures are typically long and narrow while being functionally controllable from a proximal end of the instrument. 
   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 receives a staple cartridge having 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 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. 
   Recently, an improved “E-beam” firing bar was described for a surgical stapling and severing instrument that advantageously included a top pin that slides within an internal slot formed in the upper jaw (anvil) and has a middle pin and bottom foot that slides on opposite sides of a lower jaw of an end effector, or more particularly a staple applying assembly. Distal to the middle pin, a contacting surface actuates a staple cartridge held within an elongate staple channel that forms the lower jaw. Between the contacting surface and the top pin, a cutting surface, or knife, severs tissue clamped between the anvil and the staple cartridge of the lower jaw. Since both jaws are thus engaged by the E-beam, the E-beam maintains a desired spacing between the jaws to ensure proper staple formation. Thus, if a lesser amount of tissue is clamped, the E-beam holds up the anvil to ensure sufficient spacing for the staples to properly form against an undersurface of the anvil. In addition, if a greater amount of tissue is clamped, the E-beam draws down the anvil to ensure that the spacing does not exceed the length of the staple such that ends of each staple are not sufficiently bent to achieve a desired degree of retention. Such an E-beam firing bar is described in U.S. patent application Ser. No. 10/443,617, entitled “Surgical Stapling Instrument Incorporating an E-Beam Firing Mechanism”, filed on May 20, 2003, the disclosure of which is hereby incorporated by reference in its entirety. 
   While an E-beam firing bar has many advantages for a surgical stapling and severing instrument, often it is desirable to sever and staple tissue of various thicknesses. A thin layer of tissue may result in staples that only form loosely, perhaps requiring the need for bolstering material. A thick layer of tissue may result in formed staples that exert a strong compressive force on the captured tissue, perhaps resulting in necrosis, bleeding or poor staple formation/retention. Rather than limiting the range of tissue thicknesses that are appropriate for a given surgical stapling and severing instrument, it would be desirable to accommodate a wider range of tissue thickness with the same surgical stapling and severing instrument. 
   Consequently, a significant need exists for an improved surgical stapling and severing instrument that incorporates a staple applying assembly (end effector) that adjusts to the amount of tissue that is clamped. 
   BRIEF SUMMARY OF THE INVENTION 
   The invention overcomes the above-noted and other deficiencies of the prior art by providing a surgical instrument that incorporates a firing bar that translates through a staple applying assembly having a lower jaw and a pivotally attached upper jaw, engaging each to assist in maintaining the desired spacing between inner surfaces that compress tissue in between. Advantageously, the distance between the two jaws is allowed to flex apart slightly to allow for a larger thickness of compressed tissue, yet the firing bar prevents excessive flexure that would exceed the limits on the device to form staples through the compressed tissue. Thereby, enhanced clinical flexibility is achieved with the same surgical instrument being suitable for a larger range of surgical procedures or to accommodate variations in the patient population. 
   In one aspect of the invention, a surgical instrument has a lower jaw that includes an elongate staple channel having a longitudinal channel slot formed therein that receives a staple cartridge. Staples in the staple cartridge have a staple length sized for forming a closed staple between a range of tissue thicknesses. A firing bar has a vertical portion passing through a longitudinal anvil slot in an anvil pivotally attached to the elongate staple channel and passes through the longitudinal channel slot formed in the elongate staple channel. An upper lateral surface extending from the vertical portion exerts an inward compressive force on the anvil during firing translation and a lower lateral surface extending from the vertical portion exerts an inward compressive force on the elongate staple channel during firing translation. The firing bar advantageously accommodates the range of effective staple formation by including a resilient portion that varies in height between a staple forming undersurface of an anvil and an upper surface of the staple cartridge. 
   In another aspect of the invention, a surgical instrument has an anvil that is pivotally coupled to the elongate staple channel and includes an anvil channel that is internally formed. In particular, a vertical slot inwardly opens along a longitudinal axis of the anvil and has left and right rectangular prism-shaped recesses communicating with, bisected by, and transverse to the vertical slot, wherein said left and right rectangular prism-shaped recesses extend substantially along the longitudinal length of the vertical slot. A firing device that includes a distally presented cutting edge for severing tissue is longitudinally received between the elongate staple channel and the vertical slot of the anvil channel of the anvil. An upper member of the firing device has left and right lateral upper pins sized to slidingly engage upper and lower inner surfaces of the left and right rectangular-shaped recesses of the anvil channel. A lower member of the firing device engages the channel slot in the elongate staple cartridge. A middle member of the firing device actuates the staple cartridge by distally translating a wedge member of the staple cartridge. The firing device positively engages both the elongate staple channel and the anvil during longitudinal firing travel to provide spacing in between for staple formation. Engagement of the firing device during firing maintains vertical spacing between the elongate staple channel and the anvil resisting both pinching due to an inadequate clamped tissue and partial opening due to an excessive amount of clamped tissue. This affirmative spacing is advantageously varied within an effective range of the staple length of the staple cartridge by incorporating a resilient portion in the firing device to allow some flexure to accommodate an increased compression load due to a thicker layer of clamped tissue. 
   In yet another aspect of the invention, the surgical instrument advantageously operates through an elongate shaft with a closed end effector of upper and lower jaws suitably sized for insertion through a cannula of a trocar to an insufflated body cavity or body lumen. 
   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 the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the present invention. 
       FIG. 1  is a left side view in elevation of a surgical stapling and severing instrument with an open end effector (staple applying assembly) with a shaft partially cut away to expose a firing member of a proximal firing rod and distal firing bar guided by a frame ground and encompassed by a closure sleeve. 
       FIG. 2  is a left side view of a closed end effector (staple applying assembly) with a retracted force adjusted height firing bar consistent with the present invention of the surgical stapling and severing instrument of  FIG. 1  taken in longitudinal vertical cross section along lines  2 — 2 . 
       FIG. 3  is a left isometric view of the force adjusted (compliant) height firing bar of  FIG. 2 . 
       FIG. 4  is a left side view of a distal portion (“E-beam”) of a first version of the force adjusted height firing bar of  FIG. 2  having horizontal slits formed respectively between the top pin and cutting surface and between the middle pin and the cutting surface to enhance vertical flexure. 
       FIG. 5  is a lower left isometric view of a distal portion (“E-beam”) of a second version of the force adjusted firing bar of  FIG. 2  having a relieved lower area of an upper pin to enhance vertical flexure. 
       FIG. 6  is a front view in elevation of an upper portion of the E-beam of  FIG. 5  taken in vertical and transverse cross section through the upper pin along lines  6 — 6 . 
       FIG. 7  is a front view of an upper portion of a third version of the E-beam of  FIG. 5  taken in vertical and transverse cross section along lines  6 — 6  but further including relieved upper root attachments of the top pin for enhanced vertical flexure. 
       FIG. 8  is a front view of an upper portion of a fourth version of the E-beam of  FIG. 5  taken in vertical and transverse cross section along lines  6 — 6  but including a resilient inner vertical laminate layer instead of a relieved undersurface of the top pin for enhanced vertical flexure. 
       FIG. 9  is a front view of an upper portion of a fifth version of the E-beam of  FIG. 5  taken in vertical and transverse cross section along lines  6 — 6  but including an upper pin formed of a resilient material instead of a relieved undersurface of the upper pin for enhanced vertical flexure. 
       FIG. 10  is an upper left isometric view of a distal portion (“E-beam”) of a sixth version of the force adjusted firing bar of  FIG. 2  having resilient material upon a bottom foot to enhance vertical flexure. 
       FIG. 11  is a front view in elevation taken in vertical and transverse cross section through the padded lower foot of the end effector (staple applying assembly) of the surgical stapling and severing instrument of  FIG. 1 . 
       FIG. 12  is a left view in elevation of a distal portion (“E-beam”) of a seventh version of the force adjusted firing bar of  FIG. 2  having a proximally and upwardly extended spring arm attached to a lower foot to enhance vertical flexure. 
       FIG. 13  is a left top isometric view of a distal portion (“E-beam”) of an eighth version of the force adjusted firing bar of  FIG. 2  having a spring washer encompassing a lower foot to enhance vertical flexure. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Turning to the Drawings, wherein like numerals denote like components throughout the several views, in  FIG. 1 , a surgical stapling and severing instrument  10  includes a handle portion  12  that is manipulated to position an implement portion  14  including a fastening end effector, depicted as a staple applying assembly  16 , distally attached to an elongate shaft  18 . The implement portion  14  is sized for insertion through a cannula of a trocar (not shown) for an endoscopic or laparoscopic surgical procedure with an upper jaw (anvil)  20  and a lower jaw  22  of the staple applying assembly  16  closed by depression of a closure trigger  24  toward a pistol grip  26  of the handle portion  12 , which advances an outer closure sleeve  28  of the elongate shaft  18  to pivot shut the anvil  20 . 
   Once inserted into an insufflated body cavity or lumen, the surgeon may rotate the implement portion  14  about its longitudinal axis by twisting a shaft rotation knob  30  that engages across a distal end of the handle  12  and a proximal end of the elongate shaft  18 . Thus positioned, the closure trigger  24  may be released, opening the anvil  20  so that tissue may be grasped and positioned. Once satisfied with the tissue held in the staple applying assembly  16 , the surgeon depresses the closure trigger  24  until locked against the pistol grip  26 , clamping tissue inside of the staple applying assembly  16 . 
   Then a firing trigger  32  is depressed, drawn toward the closure trigger  24  and pistol grip  26 , thereby distally advancing a firing member, depicted as including a proximal firing rod  34  attached to a distal firing bar  36 , that is supported within a frame ground  38  that connects the handle portion  12  to the staple applying assembly  16 . The firing bar  36  engages an elongate staple channel  40  and actuates a staple cartridge  42  contained therein, both forming the lower jaw  22 . The firing bar  36  also engages the closed anvil  20 . After releasing the firing trigger  32  to retract the firing bar  36 , depression of a closure release button  44  unclamps the closure trigger  24  so that the closure sleeve  28  may be retracted to pivot and open the anvil  20  to release the severed and stapled tissue from the staple applying assembly  16 . 
   In  FIG. 2 , the staple applying assembly  16  is closed upon compressed tissue  46 . In  FIGS. 2–3 , the firing bar  36  has a proximal portion  48  that is attached to a distal E-beam  50  that translates within the staple applying assembly  16 . As depicted with the firing bar  36  retracted, a vertical portion  52  of the E-beam  50  resides essentially aft of the staple cartridge  42 , as after a new staple cartridge  42  has been inserted into the elongate staple channel  40 . An upper pin  54  that extends laterally from an upper portion of the vertical portion  52  of the E-beam  50  initially resides within an anvil pocket  56  recessed near a proximal pivoting end of the anvil  20 . As the E-beam  50  is distally advanced during firing, the vertical portion  52  passes through a narrow longitudinal anvil slot  58  ( FIGS. 1 ,  11 ) formed in an undersurface  60  of the anvil  20 , a proximally open vertical slot  62  formed in the staple cartridge  42  and an underlying longitudinal channel slot  64  formed in the elongate staple channel  40 . 
   In  FIGS. 2 ,  11 , the narrow longitudinal anvil slot  58  ( FIG. 2 ) communicates upwardly to a laterally widened longitudinal anvil channel  66  sized to slidingly receive the upper pin  54 . The longitudinal channel slot  64  communicates downwardly to a laterally widened longitudinal channel track  68  that receives a lower foot  70 , which is sized to slide therein and is attached at a bottom of the vertical portion  52  of the E-beam  50 . A laterally widened middle pin  72  extending from the vertical portion  52  of the E-beam  50  is positioned to slide along a top surface of a bottom tray  74  of the staple cartridge  42 , which in turn rests upon the elongate staple channel  40 . A longitudinal firing recess  75  formed in the staple cartridge  42  above the bottom tray  74  is sized to allow the middle pin  72  to translate through the staple cartridge  42 . 
   A distal driving surface  76  of the vertical portion  52  of the E-beam  50  is positioned to translate through the proximally open vertical slot  62  of the staple cartridge  42  and distally drive a wedge sled  78  proximally positioned in the staple cartridge  42 . The vertical portion  52  of the E-beam  50  includes a cutting surface  80  along a distal edge above the distal driving surface  76  and below the upper pin  54  that severs the clamped tissue  46  simultaneously with this stapling. 
   With particular reference to  FIG. 11 , it should be appreciated that the wedge sled  78  drives upwardly staple drivers  82  that in turn drive upwardly staples  83  out of staple apertures  84  formed in a staple body  85  of the staple cartridge  42  to form against the undersurface  60  of the anvil  20  ( FIG. 2 ). 
   In  FIGS. 2 ,  11 , advantageously, the illustrative spacing, denoted by arrow  86  ( FIG. 2 ), between the upper pin  54  is compliantly biased toward a compressed state wherein 0.015 inches of compressed tissue  46  is contained in the staple applying assembly  16 . However, a larger amount of compressed tissue  46  up to about 0.025 inches is allowed by an inherent flexure of the E-beam  50 . Excessive flexure, of perhaps up to 0.030 inches, is avoided should the length of staples be insufficient to form with the additional height. It should be appreciated that these dimensions are illustrative for a staple height of 0.036 inches. The same would be true for each category of staple, however. 
   In  FIG. 4 . a first version of a compliant E-beam  50   a  includes top and bottom horizontal slits  90 ,  92  from a distal edge of the vertical portion  52   a , perhaps formed by electro drilling machine (EDM). The vertical portion  52   a  thus contains a vertically compliant top distally projecting arm  94  containing the upper pin  54 , a knife flange  96  containing the cutting surface  80 , and a lower vertical portion  98  containing the distal driving surface  76 , middle pin  72  and lower foot  70 . The horizontal slits  90 ,  92  allow a compliant vertical spacing by allowing the top distally arm  94  to pivot upwardly to adjust to increased force from compressed tissue  46  (not shown). 
   In  FIGS. 5–6 , a second version of a compliant E-beam  50   b  includes left and right lower relieved areas  110 ,  112  formed into an upper pin  54   b  to each side of the vertical portion  52 , leaving left and right lower bearing points  114 ,  116  respectively. The outboard position of the bearing points  114 ,  116  provides a long moment arm to exert the force to flex. It should be appreciated given the benefit of the present disclosure that the dimensions of the relieved areas  110 ,  112  and the choice of materials for the compliant E-beam  50   b  may be selected for a desired degree of flexure, given the staple size and other considerations. 
   In  FIG. 7 , a third version of a compliant E-beam  50   c  is as described above in  FIGS. 5–6  with further flexure provided by left and right upper narrow relieved areas  120 ,  122  formed into opposite top root surfaces of an upper pin  54   c  proximate to the vertical portion  52 . 
   In  FIG. 8 , a fourth version of a compliant E-beam  50   d  is as described for  FIGS. 2–3  with an added feature of a composite/laminate vertical portion  52   d  that includes a central resilient vertical layer  130  sandwiched between left and right vertical layers  132 ,  134  that support respectively left and right portions  136 ,  138  of an upper pin  54   d . As the left and right portions  136 ,  138  are flexed either up or down, the resulting bowing of the left and right vertical layers  132 ,  134  are accommodated by a corresponding compression or expansion of the central resilient vertical layer  130 . 
   In  FIG. 9 , a fifth version of a compliant E-beam  50   e  is as described for  FIGS. 2–3  with an added feature of a discrete upper pin  54   e  formed of a more flexible material that is inserted through a horizontal aperture  140  through a vertical portion  52   e . Thus, left and right outer ends  142 ,  144  of the discrete upper pin  54   e  flex in accordance with loading forces. 
   Alternatively or in addition to incorporating flexure into an upper pin  54 , in  FIGS. 10–11 , a sixth version of a compliant E-beam  50   f  as described for  FIGS. 2–3  further includes resilient pads  150  that are attached to upper surfaces  152  of the bottom foot  70 . The resilient pads  150  adjust the spacing of the upper pin  54  in accordance to the compression force experienced at the bottom foot  70 . 
   In  FIG. 12 , a seventh version of a compliant E-beam  50   g  is as described above for  FIGS. 2–3  with the added feature of a bottom foot (shoe)  70   g  having an upwardly aft extended spring finger  160  that resiliently urges the E-beam  50   g  downwardly to adjust vertical spacing in accordance with loading force. 
   In  FIG. 13 , an eighth version of a compliant E-beam  50   h  is as described above in  FIGS. 2–3  with the added feature of an oval spring washer  170  resting upon the bottom foot  70  encircling the vertical portion  52  and having an upwardly bowed central portion  172  that resiliently urges the E-beam  50   h  downwardly to adjust vertical spacing in accordance with loading force. 
   While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications may readily appear to those skilled in the art. 
   For example, while a manually operated surgical stapling and severing instrument  10  is depicted for clarity, it should be appreciated that robotically manipulated and/or controlled fastening devices may incorporate a force controlled firing bar. 
   For another example, a compliant E-beam consistent with aspects of the present invention may include engagement to an anvil similar to the engagement in the illustrative versions of two structures that slide against opposite sides of the elongate staple channel. Similarly, a compliant E-beam may engage a lower jaw by having a laterally widened portion that slides internally within a channel formed in a lower jaw structure. 
   As yet an additional example, in the illustrative version, the staple cartridge  42  is replaceable so that the other portions of the staple applying assembly  16  may be reused. It should be appreciated given the benefit of the present disclosure that applications consistent with the present invention may include a larger disposable portion, such as a distal portion of an elongate shaft and the upper and lower jaws with a staple cartridge permanently engaged as part of the lower jaw. 
   As yet another example, the illustrative E-beam advantageously affirmatively spaces the upper and lower jaws from each other. Thus, the E-beam has inwardly engaging surfaces that pull the jaws together during firing in instances where a larger amount of compressed tissue tends to spread the jaws. Thereby the E-beam prevents malformation of staples due to exceeding their effective length. In addition, the E-beam has outwardly engaging surfaces that push the jaws apart during firing in stances where a small amount of tissue or other structure attributes of the instrument tend to pinch the jaws together that may result in staple malformation. Either or both functions may be enhanced by applications consistent with aspects of the invention wherein inherent flexure in the E-beam adjusts to force to allow a degree of closing of the jaws or of opening of the jaws.