Abstract:
A disposable loading unit is provided which includes a tool assembly and a body portion. A drive assembly is movably positioned at least partly within the body portion and is operably associated with the tool assembly to operate the tool assembly. A locking mechanism is provided for maintaining the drive assembly in a prefired position prior to and during attachment of a DLU to a surgical instrument. The locking mechanism includes a locking member and a locking member actuator. The locking member actuator is movable to move the locking member to an unlocked position in response to linear insertion of an insertion tip of the DLU into a surgical instrument.

Description:
BACKGROUND  
       [0001]     1. Technical Field  
         [0002]     The present disclosure relates to a disposable loading unit (“DLU”) or single use loading unit (“SULU”) for use with a surgical device. More particularly, the present disclosure relates to a DLU or SULU for use with a surgical instrument which includes a locking mechanism for retaining a drive assembly of the loading unit in its prefired position until the loading unit is attached to a surgical device. For simplicity, hereinafter, SULU or DLU will be referred to as “DLU”, but it should be understood to include either or both a DLU or SULU.  
         [0003]     2. Background of Related Art  
         [0004]     Surgical devices for applying fasteners, e.g., staples, clips, etc., to tissue are well known. Such devices include single use devices which are preloaded with a single fastener and are disposable after a single use of the device. Such devices also include multiple use devices which are preloaded with a plurality of fasteners and are disposable after the supply of fasteners has been exhausted or a surgical procedure has been completed. If the supply of fasteners is exhausted prior to completion of a surgical procedure, a new device may be required to complete the surgical procedure. The use of additional surgical devices for a single surgical procedure can be expensive.  
         [0005]     In order to address the high expense of using multiple surgical devices for a single procedure, surgical devices having replaceable fastener cartridges have been developed. In such devices, fasteners are housed within a cartridge. When the fasteners in the cartridge have been exhausted, the cartridge can be removed from the surgical device and replaced with a new cartridge having an additional supply of fasteners.  
         [0006]     Tyco Healthcare Group, LP, the assignee of the present application, has manufactured and marketed endoscopic stapling devices having replaceable cartridges, such as the Multifire ENDO GIA™ 30 and Multifire ENDO GIA™ 60 devices, for a number of years. These devices include a surgical stapling apparatus and a DLU. Typically, the DLU includes a proximal body portion and a distal tool member and is attached to a surgical apparatus immediately prior to surgery. The distal tool member includes a cartridge housing a plurality of staples. After use, the DLU can be removed from the apparatus and replaced with a new DLU to perform additional stapling and/or cutting operations. A drive assembly is supported within the DLU and is engageable with a control rod of the surgical apparatus to facilitate operation of the apparatus.  
         [0007]     Although, these devices have provided significant clinical benefits, improvements to these devices are still possible. Accordingly, it would be desirable to provide an improved DLU for a surgical fastener applying device which retains or locks the DLU drive assembly in a prefired position until the DLU is attached to the surgical fastener applying device.  
       SUMMARY  
       [0008]     In accordance with the present disclosure, a DLU is provided which includes a body portion and a tool assembly. A drive assembly is movably supported within the body portion from a retracted position to an advanced position. A locking member is supported on the body portion and is movable from a first position engaging the drive assembly to a second position disengaged from the drive assembly. A locking member actuator is operably engaged with the locking member to move the locking member from its first position to its second position when the DLU is inserted linearly into the distal end of a surgical instrument.  
         [0009]     In one embodiment, the locking member includes a cam member which is slidably positioned within a cam slot formed in the locking member actuator. The locking member actuator is slidably positioned within a linear slot formed in the body portion and the locking member is slidably positioned within a transverse slot formed in the body portion. The locking member actuator includes an abutment member which is positioned on and extends radially outwardly from an insertion tip of the body portion. The abutment member is positioned to engage a surface on a surgical instrument when the body portion insertion tip is inserted into the distal end of a surgical instrument during attachment of the DLU to the surgical instrument. Engagement between the abutment member and the surgical instrument effects linear movement of the locking member actuator from a retracted position to an advanced position. Advancement of the locking member actuator is translated to transverse movement of the locking member from its first position to its second position via interaction between the cam member of the locking member and the cam slot of the locking member actuator.  
         [0010]     In one embodiment, a biasing member, e.g., a spring, is provided to urge the locking member actuator to its retracted position. In the retracted position of the locking member actuator, the locking member is maintained in its first or locked position.  
         [0011]     In one embodiment, the locking member includes a finger which is dimensioned to be received within a notch or recess formed in the drive assembly. In the first position of the locking member, the finger is positioned within the notch to prevent movement of the drive assembly from a retracted to an advanced position. Alternately, other engagement configurations are contemplated.  
         [0012]     In one embodiment, the tool assembly includes a cartridge assembly and an anvil assembly which is movable in relation to the cartridge assembly between open and approximated positions. The tool assembly may include a linear cartridge assembly which includes a plurality of linear rows of staples, e.g., six. The tool assembly may also include knife blade which can be supported on a distal end of the drive assembly. The tool assembly may also be pivotally mounted to the body portion. Alternately, the presently disclosed locking mechanism may be incorporated into other surgical devices including staplers, clip appliers and other hand held or robotically controlled devices. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     Various embodiments of the presently disclosed DLU are disclosed herein with reference to the drawings, wherein:  
         [0014]      FIG. 1  is a side perspective view from the proximal end of one embodiment of the presently disclosed DLU;  
         [0015]      FIG. 2  is a side perspective view of the distal end of the proximal body portion, the mounting assembly and tool assembly with parts separated of the DLU shown in  FIG. 1 ;  
         [0016]      FIG. 3  is a side perspective view of the mounting assembly and the proximal body portion of the DLU shown in  FIG. 1  with parts separated;  
         [0017]      FIG. 4  is a side cross-sectional view of the tool assembly of the DLU shown in  FIG. 1 ;  
         [0018]      FIG. 5  is a top perspective view of the lock member actuator of the locking mechanism of the proximal body portion shown in  FIG. 3 ;  
         [0019]      FIG. 6  is a bottom perspective view of the locking member of the locking mechanism of the proximal body portion shown in  FIG. 3 ;  
         [0020]      FIG. 7  is a top view of the proximal end of the proximal body portion of the DLU shown in  FIG. 1  with the locking mechanism in its locked position;  
         [0021]      FIG. 8  is a cross-sectional view taken along section lines  8 - 8  of  FIG. 7 ;  
         [0022]      FIG. 9  is a top view of the proximal end of the proximal body portion of the DLU shown in  FIG. 1  with the locking mechanism in its unlocked position;  
         [0023]      FIG. 10  is a cross-sectional view taken along section lines  10 - 10  of  FIG. 9 ;  
         [0024]      FIG. 11  is a side perspective view of the DLU shown in  FIG. 1  and a surgical instrument prior to attachment of the DLU to the surgical instrument;  
         [0025]      FIG. 12  is a top view of the proximal end of the DLU shown in  FIG. 1  prior to attachment to the distal end of a surgical instrument;  
         [0026]      FIG. 13  is a top view of the proximal end of the DLU shown in  FIG. 1l  as the DLU is advanced linearly into the distal end a surgical instrument;  
         [0027]      FIG. 14  is a top view of the proximal end of the DLU shown in  FIG. 12  after the DLU has been advanced linearly in relation to the distal end of a surgical instrument but prior to rotatably locking the DLU to the surgical instrument;  
         [0028]      FIG. 15  is a top view of the proximal end of the DLU shown in  FIG. 13  after the DLU has been advanced linearly in relation to and rotatably locked onto the surgical instrument; and  
         [0029]      FIG. 16  is a side perspective view from the distal end of the surgical instrument and DLU shown in  FIG. 11  attached together. 
     
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
       [0030]     Embodiments of the presently disclosed DLU will now be described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views.  
         [0031]     Referring to  FIG. 1 , briefly, DLU  16  includes a tool assembly  17 , a proximal body portion  200  and a mounting assembly  202 . Body portion  200  has a proximal end adapted to releasably engage the distal end of a surgical instrument  500  ( FIG. 11 ) in the manner to be discussed in detail below. Mounting assembly  202  is pivotally secured to a distal end of body portion  200  and is fixedly secured to a proximal end of tool assembly  17 . Pivotal movement of mounting assembly  202  about an axis perpendicular to a longitudinal axis of body portion  200  effects articulation of tool assembly  17  between an orientation aligned with the longitudinal axis of body portion  200  and an orientation at an angle to the longitudinal axis of body portion  200 .  
         [0032]     Referring also to  FIGS. 2-4 , tool assembly  17  includes a cartridge assembly  18  and an anvil assembly  20 . Anvil assembly  20  includes an anvil portion  28  having a plurality of staple deforming concavities  30  ( FIG. 4 ) and a cover plate  32  secured to a top surface of anvil portion  28 . Cover plate  32  and anvil portion  28  define a cavity  34  ( FIG. 4 ) therebetween which is dimensioned to receive a distal end of a drive assembly  212  ( FIG. 3 ). Cover plate  32  encloses the distal end of drive assembly  212  to prevent pinching of tissue during actuation of DLU  16 . A longitudinal slot  38  extends through anvil portion  28  to facilitate passage of a retention flange  40  of drive assembly  212 . A camming surface  42  formed on anvil portion  28  is positioned to engage a pair of cam members  40   a  supported on retention flange  40  of drive assembly  212  to effect approximation of the anvil and cartridge assemblies. A pair of pivot members  44  formed on anvil portion  28  are positioned within slots  46  formed in a cartridge assembly carrier  48  to guide anvil portion  28  between its spaced and approximated positions. A pair of stabilizing members  50  engage a respective shoulder  52  formed on carrier  48  to prevent anvil portion  28  from sliding axially in relation to staple cartridge  54  as camming surface  42  is pivoted about pivot members  44 .  
         [0033]     Cartridge assembly  18  includes carrier  48  which defines an elongated support channel  56  which is dimensioned and configured to receive staple cartridge  54 . Corresponding tabs  58  and slots  60  formed along staple cartridge  54  and elongated support channel  56 , respectively, function to retain staple cartridge  54  at a fixed location within support channel  56 . A pair of support struts  62  formed on staple cartridge  54  are positioned to rest on side walls of carrier  48  to further stabilize staple cartridge  54  within support channel  56 .  
         [0034]     Staple cartridge  54  includes retention slots  64  ( FIG. 2 ) for receiving a plurality of staples or fasteners  66  and pushers  68 . A plurality of laterally spaced apart longitudinal slots  70  extend through staple cartridge  54  to accommodate upstanding cam wedges  72  of an actuation sled  74  ( FIG. 2 ). A central longitudinal slot  76  extends along substantially the length of staple cartridge  54  to facilitate passage of a knife blade  78  ( FIG. 4 ). During operation of surgical stapler  10 , drive assembly  212  abuts actuation sled  74  and pushes actuation sled  74  through longitudinal slots  70  of staple cartridge  54  to advance cam wedges  72  into sequential contact with pushers  68 . Pushers  68  translate vertically along cam wedges  72  within fastener retention slots  64  and urge fasteners  66  from retention slots  64  into staple deforming cavities  30  ( FIG. 4 ) of anvil assembly  20 .  
         [0035]     Referring to  FIG. 3 , mounting assembly  235  includes an upper mounting portion  236  and a lower mounting portion  238 . A centrally located pivot member  284  extends from each of upper and lower mounting portions  236  and  238  through respective openings  246   a  formed in coupling members  246 . Coupling members  246  each include an interlocking proximal portion  246   b  configured to be received in grooves  290  formed in the proximal end of an inner housing which is formed from upper and lower housing halves  250  and  252 . Coupling members  246  retain mounting assembly  235  and upper and lower housing halves  250  and  252  in a longitudinally fixed position in relation to each other.  
         [0036]     Upper housing half  250  and lower housing half  252  are contained within an outer sleeve  251  of body portion  200 . Body portion  251  includes a cutout  251  a dimensioned to receive a boss or projection  250   a  formed on upper housing half  250   a . The positioning of projection  250   a  within cutout  251   a  prevents axial and rotational movement of upper and lower housing halves  250  and  252  within outer sleeve  251  of body portion  200 . In one embodiment, boss  250   a  has a substantially rectangular configuration having a greater axial dimension than lateral dimension. The greater axial dimension provides increased surface area for preventing rotation of upper and lower housing halves  250  and  252  within sleeve  251 . A proximal portion  250   b  of boss  250   a  is ramped. Ramped proximal portion  250   b  allows sleeve  251  to be slid over boss  250   a  as upper and lower housing halves  250  and  252  are positioned within sleeve  251 . It is envisioned that boss  250   a  may assume other configurations, e.g., circular, square, triangular, etc., and still achieve its intended function. Further, boss  250   a  can be repositioned anywhere along upper housing half  250  or, in the alternative, be positioned on lower housing half  252  or partly on each housing half  250  and  252 .  
         [0037]     The proximal end or insertion tip  193  of upper housing half  250  includes engagement nubs  254  for releasably engaging the distal end of a surgical instrument in a bayonet type fashion. Housing halves  250  and  252  define a channel  400  for slidably receiving axial drive assembly  212  therein. An articulation link  256  is dimensioned to be slidably positioned within a slot  402  formed between upper and lower housing halves  250  and  252 . A pair of H-block assemblies  255  are positioned adjacent the distal end of housing portion  200  and adjacent the distal end of axial drive assembly  212  to prevent outward buckling and bulging of drive assembly  212  during articulation and firing of surgical stapling apparatus  10 . Each H-block assembly  255  includes a flexible body  255   a  which includes a proximal end fixedly secured to body portion  200  and a distal end fixedly secured to mounting assembly  235 .  
         [0038]     A retention member  288  is supported on engagement section  270  of axial drive assembly  212 . Retention member  288  includes a pair of fingers  288   a  which are releasably positioned within slots or recesses  252   a  formed in lower housing half  252 . In operation, when SULU  16  is attached to a surgical instrument and axial drive assembly  212  is actuated by applying a predetermined force to an actuation member  516  of the surgical instrument  500  ( FIG. 11 ), axial drive assembly  212  is advanced distally to move drive assembly  212  and retention member  288  distally. As retention member  288  is advanced distally, fingers  288   a  are forced from recesses  252   a  to provide an audible and tactile indication that the surgical instrument has been actuated. Retention member  288  is designed to prevent inadvertent partial actuation of DLU  16 , such as during shipping, by maintaining axial drive assembly  212  at a fixed position within DLU  16  until a predetermined axial force has been applied to axial drive assembly  212 .  
         [0039]     Axial drive assembly  212  includes an elongated drive beam  266  including a distal working head  268  and a proximal engagement section  270 . In one embodiment, drive beam  266  is constructed from multiple stacked sheets of material. Engagement section  270  includes a pair of resilient engagement fingers  270   a  and  270   b  which mountingly engage a pair of corresponding retention slots formed in drive member  272 . Drive member  272  includes a proximal porthole  274  configured to receive distal end of a control rod  520  ( FIG. 11 ) of a surgical instrument when the proximal end of DLU  16  is engaged with the body portion  412  of a surgical instrument  500 .  
         [0040]     Referring also to  FIGS. 5-10 , DLU  16  further includes a locking mechanism including a locking member  300  and a locking member actuator  302 . Locking member  300  ( FIG. 6 ) is rotatably supported within a longitudinal or axial slot  310  ( FIG. 7 ) formed in a proximal portion of upper housing half  250  of body portion  200  of DLU  16 . Locking member  300  is movable from a first position ( FIGS. 7 and 8 ), in which locking member  300  maintains drive assembly  212  in a prefired position, to a second position ( FIGS. 9 and 10 ), in which drive assembly  212  is free to move axially.  
         [0041]     As illustrated in  FIG. 6 , locking member  300  includes semi-cylindrical body  312  which is slidably positioned within transverse slot  310  formed in upper housing half  250  of body portion  200 . Body  312  includes a radially inwardly extending cam member  314  and a radially inwardly extending finger  316 . Finger  316  is dimensioned to be slidably received within a notch or slot  270   c  ( FIG. 3 ) formed in drive assembly  212 . Engagement of finger  316  in notch  270   c  of drive assembly  212  prevents drive assembly  212  from moving linearly within body portion  200  and, thus, prevents actuation of DLU  16 .  
         [0042]     Referring to  FIGS. 3, 5  and  7 , a locking member actuator  302  is slidably positioned within a axial slot  320  ( FIG. 7 ) formed in upper housing half  250  of body portion  200  of DLU  16 . Actuator  302  includes a proximal abutment member  322 , a distal spring guide  324 , and a central cam slot  326 . Axial slot  320  intersects transverse slot  310  such that cam member  314  of locking member  300  is slidably positioned within cam slot  326  of locking member actuator  302 . A biasing member or spring  328  ( FIG. 7 ) is positioned about spring guide  324  between a distal surface  330  of actuator  302  and a wall  332  ( FIG. 7 ) defining the distal end of axial slot  320 . Spring  328  urges actuator  302  to its retracted position within axial slot  320 . In its retracted position, abutment member  322  is positioned on and extends radially outwardly of the proximal end of DLU  16  adjacent insertion tip  193  of proximal body portion  200  and cam slot  326  is positioned to locate cam member  314  such that finger  316  of lock member  300  is positioned within notch  270   c  of drive assembly  212 .  
         [0043]      FIGS. 11-16  illustrate DLU  16  and surgical instrument  500  prior to and during attachment of DLU  16  to surgical instrument  500 . Referring to  FIGS. 11-13 , surgical instrument  500  includes a handle portion  510  and body portion  512 . Handle portion  510  includes a stationary handle  514  and a movable handle  516 . Movable handle  516  is movable in relation to stationary handle  514  to advance a control rod  520  which projects from a distal end of body portion  512 . Surgical instrument  500  may be the stapling instrument disclosed in U.S. Pat. No. 6,330,965 which is incorporated herein in its entirety by reference.  
         [0044]     Prior to attachment of DLU  16  onto surgical instrument  500 , spring  328  urges actuator  302  to its retracted position to move lock member  300  to its locked position as discussed above. When insertion tip  193  DLU  16  is linearly inserted into the open end  522  ( FIG. 11 ) of the body portion  512  ( FIG. 13 ) of a surgical instrument  500 , nubs  254  move linearly through slots (not shown) formed in open end  522  of body portion  512 . As nubs  254  pass through the slots, the proximal end  322   a  of abutment member  322 , which is angularly offset from nubs  254 , abuts a wall  276   c  defining the slots for receiving nubs  254 . As DLU  16  is moved further into body portion  512 , locking member actuator  302  is moved from its retracted position to its advanced position in the direction indicated by arrow “T” in  FIG. 14 . As actuator  302  is moved to its advanced position, lock member  300  is cammed in the direction indicated by arrow “U” in  FIG. 14  from its locked position ( FIG. 8 ) engaged with drive assembly  212  to its unlocked position ( FIG. 10 ) to move finger  316  from notch  270   c . The locking mechanism including locking member  300  and locking member actuator  302  prevents accidental or inadvertent advancement or manipulation of the drive member of DLU  16  such as during loading of DLU  16  onto a surgical instrument  500 .  
         [0045]     When DLU  16  has been moved linearly in relation to instrument  500  to a position wherein a proximal surface  530  of body portion  200  abuts inner surface  276   c  of body portion  512  ( FIG. 15 ), DLU  16  can be rotated in relation to body portion  512  in a bayonet type action to position nubs  254  within openings  536  of body portion  512  to lock DLU  16  onto body portion  512 . It is envisioned that other coupling types besides bayonet couplings may be used to connect DLU  16  to instrument  500 , e.g., spring detent or snap-fit couplings, friction fit couplings, interlocking members, threaded couplings etc.  
         [0046]     It will be understood that various modifications may be made to the embodiments disclosed herein. For example, the above-described lock assembly may be incorporated into a variety of surgical instruments which include DLU&#39;s and is not limited to use on linear staplers. Further, the DLU may be configured to receive an insertion tip of surgical instrument in contrast to that disclosed. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.