Abstract:
A surgical stapler is disclosed including a first body portion supporting an anvil plate defining a fastener forming surface, and a second body portion releasably mating with the first body portion. A disposable loading unit is removably supported in the second body portion and includes a cartridge defining a plurality of slots, a plurality of surgical fasteners disposed in the slots, a plurality of ejectors positioned adjacent the surgical fasteners, and a wedged actuator for sequentially interacting with the ejectors. An elongated actuation member is mounted for longitudinal movement within the second body portion and is releasably engageable with the wedged actuator. A locking mechanism having a locking member and a biasing member is included in the second body portion.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of copending U.S. application Ser. No. 09/765,805, filed Jan. 19, 2001, which is a continuation of U.S. application Ser. No. 09/366,583, filed Aug. 4, 1999, now U.S. Pat. No. 6,202,914, which is a divisional of U.S. application Ser. No. 08/549,580, filed Oct. 27, 1995, now U.S. Pat. No. 5,941,442. The priority of these prior applications is expressly claimed and their disclosures are hereby incorporated by reference in their entirety. 
     
    
     
       BACKGROUND  
         [0002]    1. Technical Field  
           [0003]    This application relates to surgical staplers, and more particularly, to an apparatus for sequentially applying a plurality of surgical fasteners to body tissue.  
           [0004]    2. Background of Related Art  
           [0005]    Surgical devices wherein tissue is first grasped or clamped between opposing jaw structure and then joined by means of surgical fasteners are well known in the art. In some instruments, a knife is provided to cut the tissue which has been joined by the fasteners. The fasteners are typically in the form of surgical staples however, two part polymeric fasteners are also utilized.  
           [0006]    Instruments for this purpose can comprise two elongated members which are respectively used to capture or clamp tissue. Typically, one of the members carries a cartridge which houses a plurality of staples arranged in at least two lateral rows while the other member comprises an anvil which defines a surface for forming the staple legs as the fasteners are driven from the cartridge. Where two part fasteners are used, this member carries the mating part, e.g. the receiver, to the fasteners driven from the cartridge. Generally, the stapling operation is effected by a pusher which travels longitudinally through the cartridge carrying member, with the pusher acting upon the staples to sequentially eject them from the cartridge. A knife may travel with the pusher between the staple rows to longitudinally cut and/or open the stapled tissue between the rows of staples. Such instruments are disclosed in U.S. Pat. Nos. 3,079,606 and 3,490,675.  
           [0007]    A later stapler disclosed in U.S. Pat. No. 3,499,591 applies a double row of staples on each side of the incision. This is accomplished by providing a cartridge assembly in which a cam member moves through an elongate guide path between two sets of staggered staple carrying grooves. Staple drive members are located within the grooves and are positioned in such a manner so as to be contacted by the longitudinally moving cam to effect ejection of the staples. Other examples of staplers are disclosed in U.S. Pat. Nos. 4,429,695, 5,065,929, and 5,156,614.  
           [0008]    Many of the prior art linear stapling devices discussed above include a significant number of moving parts, small components and machined structural elements that are costly to fabricate and time consuming to assemble. These factors add to the overall cost of the stapling devices and thus increase the costs incurred by hospitals and health care professionals, and ultimately, the patient upon which the devices are utilized. A linear stapler that could be manufactured and assembled less expensively would provide great benefits.  
         SUMMARY  
         [0009]    The subject application is directed to a linear surgical stapler that is constructed from fewer, less expensive components than known prior art staplers configured to sequentially apply a plurality of surgical staples to body tissue. The stapler includes a first body portion supporting an anvil plate which defines a fastener forming surface and a second body portion configured to releasably mate with the first body portion. In the detailed description which follows, the first and second body portions of the stapler are also referred to as the “anvil half-section” and “cartridge half-section,” respectively.  
           [0010]    A disposable loading unit is removably supported in the second body portion and includes a cartridge defining a plurality of slots and a tissue contacting surface, a plurality of surgical fasteners disposed in the slots of the cartridge, a plurality of ejectors or pushers positioned adjacent the surgical fasteners. A wedged actuator provided in the disposable loading unit is positioned and configured to enter and translate through the cartridge to sequentially interact with the pushers.  
           [0011]    The stapler in a preferred embodiment further includes an elongated actuation member mounted for longitudinal movement within the second body portion and releasably engageable with the wedged actuator, whereby longitudinal movement of the actuation member causes the wedged actuator to interact with the ejectors, driving the surgical fasteners from the cartridge to be formed against the anvil plate.  
           [0012]    The first body portion preferably includes an elongate anvil support member and a pivoting lever handle. The anvil plate is preferably formed separate from the anvil support member and includes a plurality of staple forming pockets defining the anvil forming surface. The anvil plate also includes means for engaging the anvil support member during assembly of the surgical stapler to securely fasten the anvil plate to the support member. A notched area is defined adjacent a proximal end of the anvil support member and correspondingly positioned detents are formed adjacent a proximal end of the second body portion. The notched area and the detents cooperate to facilitate relative pivotal movement of the first and second body portions when they are mated with one another.  
           [0013]    Preferably, a pair of upstanding flanges is formed on the disposable loading unit proximal of the tissue contacting surface thereof. The flanges define a structural tissue stop to limit the movement of body tissue. The flanges are also dimensioned to engage a pair of corresponding apertures formed in the anvil plate to maintain the first and second body portions in alignment with one another when the surgical stapler is in a closed or clamped position.  
           [0014]    The wedged actuator of the disposable loading unit is preferably monolithically formed from a planar piece of sheet metal during a stamping process and includes a planar base and a pair of upstanding parallel cam wedges. An upturned flange is formed at a distal end of the actuation member for releasably engaging a complementary slot formed in the base of the wedged actuator. The wedged actuator preferably further includes an upstanding support flange to which a knife blade is fastened. The knife blade is provided to form an incision in the stapled body tissue.  
           [0015]    A retaining channel depends from a distal end of the second body portion for supporting the disposable loading unit. Preferably, the disposable loading unit and the retaining channel include complementary engagement structures for releasably securing the disposable loading unit in the retaining channel. Opposed bearing structures are formed in the retaining channel at a proximal end thereof for abutting the anvil support beam when body tissue is clamped between the anvil plate and the tissue contacting surface of the cartridge. The bearing structures serve to inhibit the anvil support beam from bending as a result of the compressive forces generated during clamping.  
           [0016]    Further features of the surgical apparatus of the subject application will become more readily apparent to those skilled in the art from the following detailed description of the apparatus taken in conjunction with the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    Various embodiments of the surgical stapling apparatus of the subject application will be described hereinbelow with reference to the drawings wherein:  
         [0018]    [0018]FIG. 1A is a perspective view of a surgical stapling apparatus constructed in accordance with a preferred embodiment with the clamping handle thereof disposed in an upright open position;  
         [0019]    [0019]FIG. 1B is a perspective view of the surgical stapling apparatus illustrated in FIG. 1A with the clamping handle disposed in a closed position;  
         [0020]    [0020]FIG. 2 is an exploded perspective view of the surgical stapling apparatus of FIGS. 1A and 1B;  
         [0021]    [0021]FIG. 3 is a perspective view of the lower body portion of the surgical stapling apparatus of FIGS. 1A and 1B;  
         [0022]    [0022]FIG. 4A is a top plan view of the retention channel of the surgical stapling apparatus of FIGS. 1A and 1B;  
         [0023]    [0023]FIG. 4B is a side elevational view of the retention channel shown in FIG. 4A;  
         [0024]    [0024]FIG. 4C is a perspective view of the retention channel of FIGS. 4A and 4B with the disposable loading unit retained therein;  
         [0025]    [0025]FIG. 5 is an enlarged perspective view, with parts separated for ease of illustration, of the disposable loading unit and actuation assembly of the surgical stapling apparatus of the subject application;  
         [0026]    [0026]FIG. 5A is a cross-sectional view showing the engagement of the cartridge lip and the retention channel;  
         [0027]    [0027]FIG. 6A is a perspective view of the actuation sled of the disposable loading unit shown in FIG. 5 in a pre-formed condition;  
         [0028]    [0028]FIG. 6B is a perspective view of the actuation sled shown in FIG. 6A in a formed condition with the knife blade separated therefrom for illustrative purposes;  
         [0029]    [0029]FIG. 6C is a perspective view of the formed actuation sled shown in FIG. 6B with the knife blade mounted to the blade support portion thereof;  
         [0030]    [0030]FIG. 7 is a plan view of the preformed anvil plate which is mounted to the anvil support beam of the upper body portion of the stapling apparatus shown in FIGS. 1A and 1B;  
         [0031]    [0031]FIG. 8 is a cross-sectional view of the preformed anvil plate taken along line  8 - 8  of FIG. 7;  
         [0032]    [0032]FIG. 9 is a front end view of the preformed anvil plate illustrated in FIGS. 7 and 8;  
         [0033]    [0033]FIG. 10 is a perspective view of the upper body portion of the surgical stapling apparatus of FIGS. 1A and 1B with an enlarged localized view of a distal portion thereof illustrating the connective engagement between the anvil plate and the anvil support beam;  
         [0034]    [0034]FIG. 11 is an exploded perspective view of an embodiment utilizing a lockout mechanism to prevent reactuation of the apparatus;  
         [0035]    [0035]FIG. 11A is an enlarged cross-sectional view of the T-shaped member of the lockout mechanism;  
         [0036]    [0036]FIG. 12 is an enlarged perspective view of the actuation channel having an edge for engagement by the hook of the lockout mechanism;  
         [0037]    [0037]FIGS. 13 and 13A are side views of the lockout mechanism illustrating its movement from a non-engaged to an engaged position;  
         [0038]    [0038]FIG. 14 is a side elevational view in cross-section of the surgical stapling apparatus of the subject application with the actuation sled disposed in a pre-actuated proximal position;  
         [0039]    [0039]FIG. 15 is a side elevational view in cross-section of the surgical stapling apparatus of the subject application with the actuation sled disposed in a partially advanced position; and  
         [0040]    [0040]FIG. 16 is a side elevational view in cross-section of the surgical stapling apparatus of the subject application with the actuation sled advanced to the distal end of the cartridge at the conclusion of a staple firing procedure. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0041]    In the drawings and in the description which follows, the term “proximal”, as is traditional, will refer to the end of the apparatus which is closer to the operator, while the term “distal” will refer to the end of the apparatus which is further from the operator.  
         [0042]    Referring now to the drawings wherein like reference numerals identify similar structural elements, there is illustrated in FIGS. 1A and 1B a surgical stapling device constructed in accordance with a preferred embodiment and designated generally by reference numeral  10  which includes a cartridge half section  11 A and an anvil half section  11 B. As will become readily apparent to those having ordinary skill in the art, surgical stapler  10  is constructed in such a manner so as to substantially reduce the costs associated with its fabrication and assembly as compared to prior art linear staplers.  
         [0043]    Referring to FIGS. 2 and 3, surgical stapler  10  includes a body portion  12  defining a handle for grasping and supporting the device. A retaining channel  14  is mounted in the interior cavity  15  of body portion  12  adjacent the distal end thereof. Retaining channel  14  is dimensioned and configured to support a disposable loading unit  20 , as illustrated in FIG. 4C.  
         [0044]    As shown in FIG. 5, the disposable loading unit  20  includes a cartridge  22  having a plurality of slots which support a corresponding number of surgical staples  24 , a plurality of staple pushers or ejectors  26  adapted and configured to eject the staples from the slots when acted upon by a staple driving force, and an actuation sled  28  which is mounted to translate through cartridge  22  in a longitudinal direction to transmit a staple driving force to the ejectors. The cartridge is preferably composed of liquid crystal polymer material; although other materials are contemplated. The cartridge  22  has a lip  23  which engages the retention channel  14  to prevent inward rotation of the cartridge (see FIG. 5A).  
         [0045]    As best seen in FIG. 6A, actuation sled  28  is preferably monolithically formed from a single piece of sheet metal or a similar material which is folded into the desired structural configuration shown in FIG. 6C. In this configuration, actuation sled (staple actuator)  28  defines a base portion  30 , two upstanding cam wedges  32  and  34 , and an upstanding shank  35  which supports a knife blade  36 . Knife blade  36  is preferably spot welded to shank  35 , although other known fastening methods may be employed. As illustrated in FIG. 6B, a weldment port  37  and a winglet  39  are provided to facilitate the proper alignment and cohesion of knife blade  36  to shank  35  during fabrication. Cam wedges  32  and  34  are staggered with respect to one another so that one leads the other throughout the sled&#39;s translation through cartridge  22 . In doing so, the staple driving forces within cartridge  22  remain balanced during a staple driving operation. Longitudinal slots  22   a  and  22   b  accommodate the longitudinal translation of cam wedges  32  and  34 , while slot  22   c  accommodates the longitudinal translation of shank  35  (see FIG. 5). Although illustrated with a knife, it is also contemplated that the apparatus can be provided without a knife bade and therefore would staple tissue without making an incision.  
         [0046]    The base portion  30  of actuation sled  28  has a transverse slot  40  defined therein which is dimensioned and configured to releasably retain an upturned flange  42  formed at the distal end of elongated actuation channel  44  (FIG. 5). When the disposable loading unit  20  is placed into retaining channel  14  and actuation sled  28  is disposed in its proximal-most position, flange  42  releasably engages slot  40 . Thus, movement of actuation channel  44  moves actuation sled  28 . After a stapling operation, when the disposable loading unit is removed from the retaining channel, flange  42  is easily disengaged from slot  40 .  
         [0047]    With continued reference to FIG. 5, actuation channel  44  is defined by a base portion  45  and two parallel upstanding beams  46  and  48  of elongate configuration. The distal ends of beams  46  and  48  are staggered to match the staggered orientation of cam wedges  32  and  34 , respectively. The proximal end of each beam projects rearwardly to engage the mounting block  49  that is associated with firing knob  50 . A pair of slots  52  (only one of which is shown) are formed in mounting block  49  for receiving the proximal end of each of the upstanding beams  46 ,  48  of actuation channel  44  and the slots are provided with detents  54  for engaging apertures  56  in the beam ends to lockingly retain the beams in mounting block  49 . In use, longitudinal movement of firing knob  50  causes corresponding longitudinal translation of actuation channel  44  and actuation sled  28 .  
         [0048]    Referring to FIGS. 2 and 4C, retention channel  14  includes a base portion  60  and two upstanding parallel walls  62  and  64 . Numerical indicia are imprinted on the walls  62 ,  64  of retention channel  14  to indicate the length of the staple line. Retention structures are provided at the distal end of each of the walls  62 ,  64  to engage corresponding structures provided on the disposable loading unit  20 . In particular, notches  66   a  and  66   b  are provided for engaging corresponding protuberances, such as protuberance  67 , and slots  68   a  and  68   b  are provided for engaging corresponding detents, such as detent  69 . These structures inhibit lateral, longitudinal and perpendicular shifting of the cartridge  22  (and disposable loading unit  20 ) within the retaining channel  14 . Ramped engagement slots  70   a  and  70   b  are also defined in the opposed walls of retention channel  14  for interacting with a pair of opposed protuberances  72   a  and  72   b  (FIG. 5) to guide the disposable loading unit  20  into retention channel  14  when loaded into surgical stapler  10 .  
         [0049]    Referring again to FIG. 2, surgical stapler  10  further includes an elongate anvil support beam  80  which has a generally U-shaped cross-sectional configuration. Anvil support beam  80  and its associated structures are also referred to herein as the “anvil half-section.” The distal end portion  88  of the anvil support beam  80  in one embodiment is tapered in height h in a distal direction to provide additional support and reduce deflection during a staple firing operation. The proximal end portion  82  of support beam  80  has a notched area  84  for engaging a pair of corresponding detents  86  (only one of which is shown), which extend into the cavity  15  of body portion  12  adjacent the proximal end thereof. The detents  86  are engaged when the cartridge half-section  11   a  and anvil half-section  11   b  are mated with one another. The distal end portion  88  of anvil support beam  80  is configured to support a preformed anvil plate  90  against which staples are driven and formed during a stapling procedure.  
         [0050]    Referring to FIGS. 7 and 8, anvil plate  90  is formed from a unitary piece of metal and is cold formed and stamped to define a plurality of staple forming recesses or cups  91 . Each staple forming recess corresponds to a particular staple housed within cartridge  22 . Anvil plate  90 , as shown in FIG. 2, is provided with two opposed tangs  92   a  and  92   b  which extend inwardly to engage complementary engagement slots  93   b  (only one is shown) in anvil support beam  80  during fabrication and assembly (see FIG. 10). The cross-sectional configuration of anvil plate  90  is dimensioned to complement the cross-sectional geometry of support beam  80  (see FIG. 9). More particularly, the cavity  97  which extends along the length of the anvil plate  90  corresponds to a similar channel formed in support beam  80 . These areas accommodate shank  35  and knife blade  36  as it translates distally to form an incision in stapled body tissue during a stapling operation.  
         [0051]    A pair of rectangular apertures  95   a  and  95   b  are formed in anvil plate  90  adjacent the proximal end thereof for receiving a pair of correspondingly positioned flanges or projections  96   a  and  96   b  which project upwardly away from the tissue contacting surface (see FIGS. 2 and 4C). The interaction between aperture  95   a ,  95   b  and flanges  96   a ,  96   b  ensures that the cartridge  22  and the anvil plate  90  are properly aligned with one another during a stapling procedure. Flanges  96   a ,  96   b  are spaced proximally of tissue stop portion  61  of retention channel  14 . Portion  61  and the distal edge  13  of handle portion, best seen in FIG. 3, cooperate to prevent tissue from extending proximally.  
         [0052]    Referring again to FIG. 2, the anvil half-section of surgical stapler  10  further includes clamping handle  100  which is used to securely clamp tissue between the staple forming surface of anvil plate  90  and the tissue contacting surface of cartridge  22 . Clamping handle  100  is pivotably mounted to anvil support beam  80  about a transverse pivot pin which is not shown in the drawings. A pair of clamping hooks  102   a  and  102   b  depend from clamping handle  100  for interacting with the U-shaped clamping beam  104  supported within the internal cavity defined in handle portion  12 .  
         [0053]    When stapler  10  is assembled prior to use, the notched area  84  at the proximal end  82  of anvil support beam  80  is engaged with the cooperating detents  86  in the inner cavity  15  of body portion  12 . Thereupon, the anvil half-section is mated with the cartridge half-section, and clamping handle  100  is disposed in the upright unclamped position shown in FIG. 1A. Subsequently, when body tissue is properly disposed between the staple forming surface of anvil plate  90  and the tissue contacting surface of cartridge  22 , the anvil half section is pivoted toward the cartridge half section, about the detents in body portion  12 , such that the distal ends of clamping hooks  102   a  and  102   b  are positioned immediately adjacent the proximal end of the base of U-shaped clamping beam  104 . Concomitantly, flanges  96   a  and  96   b  engage apertures  95   a  and  95   b  in anvil plate  90  to ensure proper alignment of the anvil and the cartridge.  
         [0054]    Then, to securely clamp the captured body tissue, clamping handle  100  is pivoted from the position illustrated in FIG. 1A to that which is shown in FIG. 1B. At such a time, clamping hooks  102   a  and  102   b  engage the base of clamping beam  104 , locking the stapler in a clamped condition. During clamping, the captured body tissue exerts a counter-force against the tissue contacting surface of cartridge  22  and the fastener forming surface of the anvil plate  90 , urging the two structures apart. To overcome these forces and prevent the proximal portion  82  of anvil support beam  80  from bending, bearing surfaces are defined within the retention channel  14  to support the compressive forces generated during clamping. In particular, as illustrated in FIG. 4A, opposed bearing shelves  110   a  and  110   b  are stamp formed in the opposed walls  62  and  64  of retention channel  14 . The bearing shelves are positioned to abut the medial section of anvil support beam  80  proximate the clamping handle pivot point.  
         [0055]    It may also be desirable to provide a locking mechanism to prevent reactuation of the apparatus after it has been actuated. For example, a locking member  120  shown in FIG. 11 can be positioned in the retaining channel  114 . The locking member  120  is biased to an upward engagement position and each end extends through a window  141 ,  143  in the channel  114 . A T-shaped member  124  is positioned between the cam wedges  132 ,  134  to bias the hook portion  122  out of engagement with the actuation channel  144 . Head portion  126  of T-shaped member  124  (FIG. 11A) is initially retained in the cartridge by a pair of detents in the cartridge which extend into the knife slot. When the stapler is actuated, head portion  126  of T-shaped member  124  is positioned in the knife slot. A second pair of detents (not shown) at the distal end of the knife slot engages head portion  126  of T-shaped member  124  to hold it at the distal end of cartridge  122  when the cam wedges  132 ,  134  are advanced to the distal position. When actuation channel  144  is retracted from the post-actuated position to the pre-actuated position, the T-shaped member  124  remains forward allowing hook portion  122  to return to the upward position and extend through the window  141  in retaining channel  114  to engage edge  143  (see FIGS. 12 and 13A) of actuation channel  144  to prevent advancement of the actuation channel. FIGS. 13A, 13B illustrate movement of the locking member  120  from an initial non-engaged position (FIG. 13A) out of engagement with actuation channel  144  to an engaged position (FIG. 13B) in engagement with actuation channel  144  to prevent distal movement thereof.  
         [0056]    Referring now to FIGS.  14 - 16 , there is illustrated, in sequential order, a staple firing operation in which a plurality of staples are ejected from cartridge  22  and driven against the staple forming surface of anvil plate  90 . In operation, prior to firing surgical stapler  10 , actuation sled  28  is in the proximal-most position shown in FIG. 14. At such a time, knife blade  36  is enclosed in a protective housing  25  formed adjacent the proximal end of disposable loading unit  20 . To fire the apparatus, firing knob  50  is moved in a distal direction. Accordingly, as illustrated in FIG. 15, actuation channel  44  drives actuation sled  28  distally into and through cartridge  22 . During its distal translation, the angled leading surfaces of cam wedges  32  and  34  sequentially contact ejectors  26 , urging them in a direction transverse to the direction of movement of actuation sled  28 . As a result, the ejectors  26  push the staples  24  from their individual slots, driving each staple into a respective staple forming cup  91  in anvil plate  90 .  
         [0057]    Sequential firing of the staples continues until actuation sled  28  is advanced to the distal end of cartridge  22 , at which time, all of the staples once housed within the cartridge  22  will have been ejected (see FIG. 16). Thereafter, the firing knob  50  is retracted to its original position, the cartridge and anvil sections are separated, and the spent disposable loading unit  20  is removed from retaining channel  14 . Subsequently, a new, fully loaded disposable loading unit can be positioned in retaining channel  14  such that the slot  40  of the actuation sled  28  engages the flange  42  of actuation channel  44  to enable re-use of the apparatus.  
         [0058]    Although the subject apparatus has been described with respect to preferred embodiments, it will be readily apparent to those having ordinary skill in the art to which it appertains that changes and modifications may be made thereto without departing from the spirit or scope of the subject apparatus as defined by the appended claims.