Abstract:
A surgical device and end effector connection system therefor include an easy-to-engage mechanism for connecting a handle/shaft/actuation rod unit to an end effector. This mechanism may utilize an axially engageable inner ball/socket inner connection with a threaded outer connection, or an inner bayonet connection with either an outer bayonet connection or an outer threaded connection. In each of the embodiments, an outer portion of the end effector preferably is statically engaged with the shaft, and an inner portion of the end effector is engaged with the actuation rod such that axial movement of the actuation rod can actuate a tool end of the end effector. The present invention further relates to methods of use for the laparoscopy device.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to medical devices, and more specifically to a surgical device useful in laparoscopic procedures and having a removable end effector, as well as methods of use for the device. 
       BACKGROUND 
       [0002]    A wide variety of instruments are presently known and employed in the art of laparoscopic surgery, which typically involves gaining access to a patient&#39;s peritoneal cavity by way of an endoscope and/or trocars passing through the patient&#39;s abdominal wall. Many such medical instruments include an operable end effector in the form of cutting blades, forceps or other devices wherein the device is passed through a discrete opening providing access to the patient&#39;s interior. The opening may be surgically created (e.g. using a trocar) or naturally occurring (e.g., via the anterior or posterior openings of the alimentary canal). In such devices the surgeon must be able to manipulate adequately a distal, internally disposed end of the laparoscopic instrument to perform the required surgical routine. For this reason, laparoscopic devices are often designed such that a movable rod extending coaxially through a distally-projecting elongate shaft may be manipulated from the proximal, operative end of the instrument to manipulate a distal end effector of the instrument (e.g., forceps, scissor-type blades or the like). 
         [0003]    It is well known that in many such laparoscopic instruments, such as those employing cutting blades, it is periodically necessary to replace the blades by new and sharper blades, in which case it is often economically expedient merely to remove the tip of the instrument and replace it with a new tip, rather than discarding the entire instrument. Likewise, in order to promote device sterility and economy, it is often useful to provide a re-usable handle portion with disposable and/or interchangeable end effectors, collectively known as a resposable device. 
         [0004]    In a typical device wherein an actuation rod is proximally actuated to effect actuation of an end effector, a rod portion of the newly replaced end effector is connected to the actuation rod, and the outer shaft of the device upon which the end effector is to be assembled is attached to a casing portion of the end effector such that proper movement of the instrument occurs. Specifically, it is generally desirable that movement of the actuation rod within the outer shaft cause opening, closing, or other actuating movement of the end effector. 
         [0005]    As it may be desirable to replace an end effector during a surgical procedure, it is most desirable that the disconnection of an end effector to be discarded and that the connection of a new end effector be a relatively simple and economical operation. At the same time, it is desirable that the connection be secure to avoid risk of the end effector becoming loose during use in a patient body and that the connection provide for effective actuation of the end effector. Thus, prior art devices have employed a variety of connections. For example, some devices—an example of which is shown as device  100  in  FIG. 1A  (the distal portion of which is shown schematically in magnified longitudinal cross-section)—use a threaded engagement  106  between the actuation rod  102  and the end effector rod  104  as well as a threaded engagement  114  between the outer shaft  110  and the end effector casing portion  112 . Other devices—an example of which is shown as device  120  in  FIG. 1A  (the distal portion of which is shown in magnified longitudinal cross-section)—use a connection wherein the end effector casing  128  is threadedly connected to the device shaft  126 , and the end effector rod  122  includes a ball or hemispherical proximal tip  124  that fits from the side into a keyhole aperture  132  of the actuation rod  130 . It is preferable that the removal and replacement of an end effector require no special mechanical knowledge or capability on the part of the operator of the instrument, and that it may be done quickly and with a high degree of reliability, including in the low-light conditions commonly present in an operating suite during laparoscopic procedures. 
         [0006]    In some of the arrangements set forth above, problems may arise in the initial engagement of the end effector with the actuation rod and shaft. For example, with a dual threaded connection such as illustrated in  FIG. 1A , a user may experience difficulty in properly aligning and engaging both sets of threads in beginning the attachment of the new end effector to the instrument. As another example, with a side-mounted ball/socket inner connection such as illustrated in  FIG. 1B  (the distal portion of which is shown schematically in magnified longitudinal cross-section and rotated longitudinally 90° from the orientation of  FIG. 1A ), a user must spread the device handles to extend the actuation rod from the shaft, then align and place a ball structure on the end effector laterally into a side-opening keyhole aperture. Given the low-light conditions commonly present in a laparoscopy operating suite, this exacting operation can consume valuable time when replacing an end effector during a surgical procedure. 
         [0007]    Each of the threaded and the ball/socket types of connection provide desirably secure mounting and functional capacity for laparoscopic instruments. However, previous attempts to combine these connection means require exacting lateral motion during engagement. It is therefore desirable to provide a laparoscopic instrument assembly having a disposable end effector wherein an end effector rod is disposed for axial movement within a tubular tip casing structure, with the end effector rod and casing structure, and the actuation rod and shaft, containing complementary ball/socket and threaded means for attachment, in which the attachment is simple in construction and economical to produce. It is also desirable to provide a laparoscopic instrument assembly of the type described wherein a replaceable end effector is easily and quickly assembled onto the instrument assembly in low-light conditions without requiring special instructions to the user, one aspect of which is providing for axial assembly (i.e., where an end effector is generally moved only within the longitudinal axis of the laparoscopic instrument rather than requiring, for example, lateral alignment of some components). Bayonet-type connections may also provide similar advantages for axial connection of both the inner (end effector rod to actuation rod) and outer (end effector casing to shaft) connections, and are therefore also be desirable. 
       BRIEF SUMMARY 
       [0008]    In one aspect, the present invention provides a laparoscopy device having an easy-to-engage mechanism for connecting a handle/shaft/actuation rod unit to an end effector. This mechanism may utilize an axially engageable inner ball/socket inner connection with a threaded outer connection, or an inner bayonet connection with either an outer bayonet connection or an outer threaded connection. In each of the embodiments, an outer portion of the end effector preferably is statically engaged with the shaft, and an inner portion of the end effector is engaged with the actuation rod such that axial movement of the actuation rod can actuate a tool end of the end effector. The present invention further relates to methods of use for the laparoscopy device. 
         [0009]    In another aspect, the invention includes a surgical device. The surgical device includes a first handle member pivotably mounted to a second handle member, a generally tubular elongate shaft projecting distally from the second handle member, and an actuation rod disposed axially through the elongate shaft. The actuation rod is operatively connected near its proximal end to the first handle member, and a distal end portion of the actuation rod includes one of a ball member or a socketed prong assembly. The surgical device also includes an end effector assembly with an outer casing, an end effector rod disposed axially through the outer casing, and an actuatable tool end, with the end effector rod operably connected to the actuatable tool end. The outer casing is threadedly connectable to the elongate shaft and a proximal end portion of the end effector rod includes the other of a ball member or a socketed prong assembly which is complementary to and axially connectable to the opposite of a ball member or socketed prong assembly of the actuation rod. 
         [0010]    In a further aspect, the present invention includes an end effector connection system. The end effector connection system includes a first surgical device component and a second surgical device component and is configured for axially connecting the first surgical device component to the second surgical device component. The first surgical device component includes a generally tubular first member having a first rod disposed axially therethrough. The first rod includes a socketed prong assembly with a plurality of prongs, at least one of which includes an indented socket. The generally tubular first member includes a first threaded surface. The second surgical device component includes a generally tubular second member having a second rod disposed axially therethrough. The second rod includes a ball structure, sized to be axially engagingly received between the plurality of prongs and at least partially into the indented socket, and the generally tubular second member includes a second threaded surface complementary to and engageable with the first threaded surface. 
         [0011]    In yet another aspect, the invention includes an end effector connection system that includes a first surgical device component and a second surgical device component, with the system being configured for axially connecting the first surgical device component to the second surgical device component. The first surgical device component includes a generally tubular first member having a first rod disposed axially therethrough, and that first rod includes a male bayonet assembly comprising at least one boss extending from the first rod. The generally tubular first member also includes a first threaded surface. The second surgical device component includes a generally tubular second member having a second rod disposed axially therethrough. The second rod includes a female bayonet assembly, configured to axially engagingly receive the male bayonet assembly and the generally tubular second member includes a second threaded surface complementary to and engageable with the first threaded surface. 
         [0012]    In still another aspect, the invention includes an end effector connection system configured for axially connecting a first surgical device component to a second surgical device component. The first surgical device component includes a generally tubular first member having a first rod disposed axially therethrough. The first rod includes a first male bayonet assembly comprising at least one boss extending laterally from the first rod, and the generally tubular first member includes a second male bayonet assembly comprising at least one boss extending laterally from the generally tubular first member. The second surgical device component includes a generally tubular second member having a second rod disposed axially therethrough. The second rod includes a first female bayonet assembly, configured to axially engagingly receive the first male bayonet assembly, and the generally tubular second member includes a second female bayonet assembly, which is configured to axially engagingly receive the second male bayonet assembly. 
         [0013]    In still yet another aspect, the invention includes an end effector connection system comprising axially engageable first and second connecting means wherein the first connecting means includes an inner connecting means between an end effector rod and an actuation rod, and the second connecting means includes an outer connecting means between an end effector casing and an outer shaft. In order to lockingly engage the end effector rod with the actuation rod, the first connecting means requires no rotation greater than 360°. 
         [0014]    In another aspect, the invention includes an end effector connection system that includes axially engageable first and second inner connecting members and axially engageable first and second outer connecting members. The first and second inner connecting members are generally axially disposed in the first and second outer connecting members, respectively. The first inner connecting member includes a generally cylindrical body having a laterally protruding portion disposed near its distal end, and the second inner connecting member has a receiving aperture configured to axially receive the first inner connecting member. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIGS. 1A and 1B  illustrate a illustrate prior art end effector connection systems; 
           [0016]      FIG. 2A  illustrates a side view with partial cross-section of a surgical device of the present invention, disassembled; 
           [0017]      FIGS. 2B  depicts a side view with partial cross-section of a surgical device of the present invention, assembled; 
           [0018]      FIG. 2C  shows a longitudinal section view of an end effector embodiment of the present invention, with connecting means therefor; 
           [0019]      FIG. 2D  illustrates a perspective view of an end effector embodiment of the present invention, with connecting means therefor; 
           [0020]      FIG. 2E  shows a schematic view of ball/socket connecting means for an end effector of the present invention, 
           [0021]      FIGS. 3A-3E  depict a method of using an end effector connection system of the present invention; 
           [0022]      FIGS. 4A-4F  illustrate schematically the components of another end effector connection system of the present invention; and 
           [0023]      FIGS. 5A-5C  show schematically components of yet another end effector connection system of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    A first embodiment of a laparoscopy device  200  is illustrated with reference to  FIGS. 2A-2E .  FIG. 2A  shows a side view with partial cross-section of the disassembled device,  FIG. 2B  shows the same side view with partial cross-section of the assembled device, and  FIG. 2D  shows a partial perspective view of the distal end of the device. As illustrated in  FIGS. 2A-2E , the laparoscopy device includes two main components: a main body  201  and an end effector  230 .  FIGS. 2C and 2E  show detail views of the connection between the main body  201  and the end effector  230 . In a preferred embodiment, the main body  201  is reusable, and the end effector  230  is disposable and replaceable. The main body  201  includes a handle  202  and a shaft  220  extending distally therefrom. The handle  202  includes a thumb ring member  204  pivotably attached at a pivot pin  208  to a finger ring member  206 , which includes an upper barrel portion  206 a. The elongate tubular shaft  220  extends distally from the upper barrel portion  206 a of the finger ring member  206 . An actuation rod  222  extends distally from an upper portion of the thumb ring member  204  through the shaft  220 . This configuration provides for reciprocating axial movement of the actuation rod  222  in the shaft  220  upon pivoting the thumb ring member  204  relative to the finger ring member  206 . (Those of skill in the art will appreciate that the handle may be configured such that the thumb ring handle is static with a barrel portion attached to a shaft, and that the finger ring handle be pivotable relative to the thumb ring handle.) At the distal end of the shaft  220 , the end effector  230  is operably connected both to the shaft  220  and the actuation rod  222 . The distal end of the main body shaft  220  includes an outer threaded surface  221  that is complementary to the inner threaded surface  240  of the end effector casing  238 . The distal end portion of the actuation rod  222  includes a narrow portion  222   a  and a distal ball member  222   b.    
         [0025]    In the preferred embodiment illustrated in  FIGS. 2A-2E , the end effector  230  includes two cutting blade members  232  mounted pivotably on a pivot pin  234 . In other embodiments, one of the blade members may be fixed, or both may be replaced with, for example, forceps, graspers, needle holders, clamps, dissectors, and spreaders, or another actuatable tool end. The pivot pin  234  is mounted between distal arms  236  of a generally cylindrical end effector casing  238 . The blade members  232  each include a proximal camming aperture  232   a.  The proximal end of the end effector casing  238  includes an inner threaded surface  240 . In a preferred embodiment, the end effector casing  238  includes an electro-insulative outer coating that forms a seal with an electro-insulative outer coating of the main body shaft  220 . A generally cylindrical end effector rod  242  is mounted in a longitudinal central cavity  244  of the end effector casing  238 . 
         [0026]    The distal end portion of the end effector rod  242  includes a pair of forks  246 , between which is disposed a camming pin  248 . In the illustrated embodiment, the camming pin  248  is disposed through the camming apertures  232   a  of the blade members  232  such that distal axial movement of the end effector rod  242  cams the blade members  232  such that their distal ends move open/apart from each other, and proximal axial movement of the end effector rod  242  cams the blade members  232  such that their distal ends move closed/toward each other. The proximal end portion of the end effector rod  242  includes a socketed prong assembly having a pair of generally semi-cylindrical, proximally-extending prongs  242   a  biased toward each other. At least one of the generally flat inner prong surfaces  242   b  include one or more generally matching indentations or openings  242   c  that effectively form a socket for receiving the distal ball member  222   b  of the actuation rod  222 . In a preferred embodiment shown most clearly in  FIGS. 2C and 2E , a socket is provided by a generally cylindrical aperture  242   e  disposed perpendicular to a plane between the prongs  242   a  and disposed adjacent their distal ends. The intersection of the aperture  242   e  with the inner prong surfaces  242   b  provides a matched pair of ball-receiving openings  242   c  that form a socket for receiving the distal ball member  222   b  of the actuation rod  222 . In alternative embodiments (e.g., those embodiments with a similar or different ball member geometry), the openings  242   c  may be, for example, generally semi-cylindrical or hemi-spherical. In the embodiment shown in  FIG. 2E , the proximal ends of the generally flat inner prong surfaces  242   b  each also include a depression  242   d  configured to aid passage of the distal ball member  222   b  of the actuation rod  222  into engagement with the openings  242   c.  The ball member  222   b  may have different geometries in different embodiments within the present invention such that it may be, for example, generally spherical, generally cylindrical, or frustoconical. Also, in other embodiments within the scope of the present invention, the socketed prong assembly may include three or more prongs, at least one of which has an indentation for engaging and retaining the ball member. 
         [0027]    Together, the end effector  230  and the main body  201  include an end effector connection system. In other words, the end effector  230  is operably connectable to the main body  201  using a connecting means of the present invention as described below. When the end effector  230  is engaged with the main body  201 , the inner threaded surface  240  of the end effector casing  238  is threadedly engaged with the outer threaded surface  221  of the shaft  220 , and the distal ball member  222   b  of the actuation rod  222  is in a “snap-fit” engagement with the depressions  242   d  of the end effector proximal prongs  242 . However, those of skill in the art will appreciate that, in alternative embodiments within the scope of the present invention, the relative position of the ball and prongs may be reversed such that a proximal ball member on the end effector rod may be engagingly received by distal prongs on the actuation rod. 
         [0028]    The illustrated embodiment depicts the handle members  204 ,  206  opening in scissors-like fashion to actuate the end effector  230 . Specifically, when the handle members  204 ,  206  are together, the actuation rod  222  is retracted proximally and the blade members  232  are together in a closed state. And, as shown in  FIG. 2A , when the handle members  204 ,  206  are spread apart, the actuation rod  222  is extended distally and the blade members  232  are spread apart in an open state. This configuration allows the blade members  232  actively to be controlled for an opening motion (e.g., such as for spreading tissue) and for a closing motion (e.g., such as for grasping or cutting tissue). 
         [0029]    The above-described embodiment preferably is configured for ease of engagement by use of the following method, which is able to be conducted in low-light conditions, and which is described with reference to  FIGS. 3A-3E . First, as shown in  FIG. 3A-3B , with the device handle members  204 ,  206  (not shown) drawn together and the actuation rod  222  retracted accordingly, a user places the proximal end of the end effector casing  238  over the distal end of the main body shaft  220  and twists the end effector  220  to engage the inner end effector threads  240  with the outer shaft threads  221 . (Those of skill in the art will appreciate that, in other embodiments, the inner threads may be on the end effector, and the outer threads may be on the shaft.) Next, as shown in  FIGS. 3C-3D , the user spreads the handle members  204 ,  206  (not shown), which moves the actuation rod  222  distally such that the distal ball member  222   b  is forced axially between the prongs  242   a  of the end effector rod  242  until it is engaged by the openings  242   c  and a proximal portion of the prongs  242   a  biasedly closes about the narrow portion  222   a  of the actuation rod  222 . In a preferred embodiment, during the transition shown from  FIG. 3C , to  FIG. 3D , the user will have a tactile sensation of the snap-fit engagement of the ball member  222   b  with the socket formed by the depressions  242   d  of prongs  242   a,  and may also hear an audible click of engagement. Thereafter, as shown in  FIG. 3E , the interface of ball member  222   b  with prongs  242   a  maintains an operative engagement between the main body  201  and the end effector  230 . Specifically, the proximal ends of prongs  242   a  are captured by the main body shaft  220 , the end effector casing  238  is held generally static relative to the main body shaft  220 , and the end effector rod  242  is operatively connected to the actuation rod  222  such that actuation of the handles  204 ,  206  transmits axial movement through the actuation rod  222  to the end effector  230  to open and close the end effector blade members  232  while the end effector  230  is secured to the main body shaft  220  and actuation rod  222 . 
         [0030]    In an alternative method, the actuation rod ball member  222   b  may first be axially engaged with the end effector prongs  242   a,  and then the end effector casing  238  may be threadedly engaged with the main body shaft  220 . 
         [0031]    In preferred embodiments of the present device (such as illustrated in  FIGS. 2A-2E ), the shaft  220  includes indexed rotating means such as a rotation knob  260  with corresponding internal structure of a type known in the art, so that it can be rotated about its ( 220 ) longitudinal axis in an indexed fashion. The shaft  220  also preferably includes means for flushing its internal portion, such as a Luer port  262  with a cap  263 . Preferred embodiments of the present device  200  are configured for use with monopolar-type electrosurgical apparatus such that the exterior of the main body  201  and the end effector casing  238  are insulated, and an electrode such as a Bovie post  264  is provided to direct current from an electrosurgical generator (not shown) through the actuation rod to the tool end (e.g., blade members  232 ) where it may be used, for example, in cutting and coagulation. Those of skill in the art will also appreciate that the “ball/socket plus threaded” end effector connection system described above is also useful within the scope of the present invention for connecting a first and second surgical device component in a non-laparoscopic tool device. 
         [0032]      FIGS. 4A-4C  depict another end effector connector system  400  embodiment of the present invention. As shown in these figures, this embodiment of an end effector connection system includes an inner bayonet connection and an outer bayonet connection for connecting an end effector  402  to the main body  404  of a surgical instrument of the type shown in  FIG. 2A . 
         [0033]    The proximal portion of the instrument main body  404 , including its handle, is not shown. The main body  404  includes an actuation rod  406  disposed axially through an outer shaft  408 . A distal portion of the outer shaft  408  includes a male bayonet structure with a distal outer shaft portion  422  having an outer diameter less than that of the major length of the outer shaft  408 . The border of the distal portion  422  with the larger outer diameter of the outer shaft  408  is defined by a lip  408   a,  the surface of which is in a plane generally perpendicular to the longitudinal axis. A plurality of outer shaft bosses  424  extends radially from that distal outer shaft portion  422 . The illustrated embodiment includes four outer shaft bosses  424 , but those of skill in the art will appreciate that more or fewer bosses may be used in other embodiments. Although it is preferable to have a plurality of bosses, a single outer shaft boss may be used within the scope of the present invention. As is shown most clearly in  FIG. 4C , a distal portion of the actuation rod  406  includes a male bayonet structure with a distal actuation rod portion  412  having an outer diameter less than that of the major length of the actuation rod  406 . The border of the distal actuation rod portion  412  with the larger outer diameter of the actuation rod  406  is defined by a lip  406   a,  the surface of which is in a plane generally perpendicular to the longitudinal axis. A plurality of actuation rod bosses  414  extends radially from that distal actuation rod portion  412 , and preferably is radially offset relative to the plurality of outer shaft bosses  424 . The illustrated embodiment includes four actuation rod bosses  414 , but those of skill in the art will appreciate that more or fewer bosses may be used in other embodiments. Although it is preferable to have a plurality of bosses, a single actuation rod boss may be used within the scope of the present invention. 
         [0034]    The end effector  402  includes an outer casing  436 . A generally cylindrical end effector rod  438  is disposed in the outer casing  436  in a manner allowing axial (but not rotational) sliding movement to actuate a tool end in the same manner as described with reference to the embodiment of  FIG. 2A , or in another manner known to those of skill in the art. The tool end (e.g., blade members) is not shown, but a forked distal end  439  is provided for mounting the tool end. The proximal portion of the end effector rod  438  includes a female bayonet structure, which includes an inner receiving channel  440  and a plurality of curved, L-shaped boss-receiving slots  442 . The number of boss-receiving slots  442  preferably is the same as the number of bosses  414  on the actuation rod  406 . The proximal portion of each receiving slot is a groove  442   a  on the inner surface of the inner receiving channel  440 . The groove  442   a  preferably is generally parallel to the central longitudinal axis of the end effector  402 . The distal portion  442   b  of each slot  442  curves radially with the outer contour of the end effector rod  438 , and preferably is nearly perpendicular to the proximal slot portion  442   a,  but is slightly angled toward the distal end of the end effector  402 . In the illustrated embodiment, the distal slot portion  442   b  is open to the exterior of the end effector rod  438 . 
         [0035]    The outer casing  436  includes a female bayonet structure, which includes a generally cylindrical shaft-receiving channel  450  and a plurality of curved, L-shaped boss-receiving slots  452 . The number of boss-receiving slots  452  preferably is the same as the number of outer shaft bosses  424  on the outer shaft  408 . The proximal portion of each boss-receiving slot  452  is a groove  452   a  on the inner surface of the generally cylindrical shaft-receiving channel  450 . The groove  452   a  preferably is generally parallel to the central longitudinal axis of the end effector  402 . The distal portion  452   b  of each slot  452  curves radially with the outer contour of the outer casing  436 , and preferably is nearly perpendicular to the proximal slot portion  452   a,  but is slightly angled toward the distal end of the end effector  402 . In the illustrated embodiment, the distal slot portion  452   b  is open to the exterior of the end effector rod  438 . This open portion allows for visual verification of full engagement, as shown in  FIG. 4F . 
         [0036]    The actuation rod  406  preferably includes a longitudinal fin  426  projecting radially therefrom and engaging a complementarily-sized fin-receiving groove  428  on the inner surface of the outer shaft  408  in a manner allowing axial, but not rotational movement of the actuation rod  406  relative to the outer shaft  408 . In this manner, the rotational orientation of the actuation rod bosses  414  and the outer shaft bosses  424  is held consistently so that the female bayonet structures of the end effector  402  may readily be axially engaged with the male bayonet structures of the main body  404 . This configuration allows the outer shaft  408  and the actuation rod  406  to be rotated together, and permits axial actuation of the actuation rod  406  for transmitting movement to the tool end (not shown). 
         [0037]    A method of engaging the double bayonet end effector connection system  400  is described with reference to  FIGS. 4A-4C . To engage the end effector  402  to the main body  404 , a user axially inserts the proximal portion of the end effector rod  438  into the distal end of the main body&#39;s outer shaft  408 . The user then rotates the end effector  402  relative to the outer shaft  408  (or vice versa) to align the outer boss-receiving slots  452  of the end effector outer casing  436  with the outer shaft bosses  424  of the outer shaft  408 . This action simultaneously aligns the female bayonet member of the end effector  402  with the male bayonet member of the actuation rod  406 . As shown in  FIG. 4D , once aligned, the user moves the end effector  402  and the main body  404  axially together such that the distal end of the actuation rod  406  enters the end effector rod&#39;s inner receiving channel  440 , the outer shaft bosses  424  slide into the proximal groove portion  452   a  of each boss-receiving slot  452  of the end effector outer casing  436 , and the actuation rod bosses  414  slide into the proximal groove portion  442   a  of each boss-receiving slot  442  of the end effector rod  438 . Next, as shown in  FIG. 4E , the user rotates the end effector  402  counterclockwise relative to the outer shaft  408  (or vice versa). This rotation engages the main body bosses  414 ,  424  into the respective distal slot portions  442   b,    452   b  of the end effector. Because each of the distal slot portions  442   b,    452   b  of the end effector is slightly distally angled, this boss-slot engagement forms a frictional lock as the proximal end of the end effector rod  438  is forced against the actuation rod lip  406   a  and the proximal end of the end effector outer casing is forced against the outer shaft lip  408   a.  Each of the lips  406   a,    408   a  may alternatively include a surface-mounted gasket (not shown) that is compressed and that helps to provide a frictional lock. As shown in the illustrated embodiment, this engagement method requires only a small rotational motion after the initial axial engagement. In the illustrated embodiment, the rotation required to lock in the engagement is less than  900 . In other embodiments, including those with more or fewer bosses, the rotation required is less than 360°. 
         [0038]    For the end effector system of the surgical device embodiment illustrated in  FIGS. 2A-2E , engaging the inner connecting means (i.e., those means connecting the end effector rod with the actuation rod) does not require any rotation of either the end effector or the main body. Other connection systems including means that do require rotation to engage the inner connecting means are disclosed below, but such embodiments require rotation of less than 360°, preferably less than 180°, and most preferably less than 90°. All such connection systems provide the advantage of minimizing the amount of movement a user must employ to securely engage an end effector to a main body in a surgical device, even when some rotation (e.g., for a bayonet or threaded connection) is required to secure the outer shaft to the end effector casing. Those of skill in the art will appreciate that the ball/socket inner connection means described with reference to  FIGS. 2A-2E  may be used with an outer bayonet connector as described with reference to  FIGS. 4A-4C . 
         [0039]      FIGS. 5A-5C  illustrate another end effector connection system  500  embodiment of the present invention. As shown in these figures, this embodiment of an end effector connection system includes an inner bayonet connection and an outer threaded connection for connecting an end effector  502  to the main body  504  of a surgical instrument of the type shown in  FIG. 2A . 
         [0040]    The proximal portion of the instrument main body  504 , including its handle, is not shown. The main body  504  includes an actuation rod  506  and an outer shaft  508 . A distal portion of the outer shaft  508  includes an outer threaded surface  510 . As is shown in  FIGS. 5B-5C , a distal portion of the actuation rod  506  includes a male bayonet structure including a distal actuation rod portion  512  having an outer diameter less than that of the major length of the actuation rod  506 . The border of the distal actuation rod portion  512  with the larger outer diameter of the actuation rod  506  is defined by a lip  506   a,  the surface of which is in a plane generally perpendicular to the longitudinal axis. A plurality of bosses  514  extends radially from that distal actuation rod portion  512 . The illustrated embodiment includes four bosses  514 , but those of skill in the art will appreciate that more or fewer bosses may be used in other embodiments. Although it is preferable to have a plurality of bosses, a single boss may be used within the scope of the present invention. 
         [0041]    The end effector  502  includes an outer casing  516 . A generally cylindrical end effector rod  518  is disposed in the outer casing  516  in a manner allowing axial sliding movement to actuate a tool end in the same manner as described with reference to the embodiment of  FIG. 2A , or in another manner known to those of skill in the art. The tool end (e.g., blade members) is not shown, but a forked distal end  519  is provided for mounting the tool end. The proximal portion of the end effector rod  518  includes a female bayonet structure, which includes an inner receiving channel  520  and a plurality of curved, L-shaped boss-receiving slots  522 . The number of boss-receiving slots  522  preferably is the same as the number of bosses  514  on the actuation rod  506 . The proximal portion of each receiving slot is a groove  522   a  on the surface of the inner receiving channel  520 . The groove  522   a  preferably is generally parallel to the central longitudinal axis of the end effector  502 . The distal portion  522   b  of each slot  522  curves radially with the outer contour of the end effector rod  518 , and preferably is nearly perpendicular to the proximal slot portion  522   a,  but is slightly angled toward the distal end of the end effector  502 . In the illustrated embodiment, the distal slot portion  522   b  is open to the exterior of the end effector rod  518 . 
         [0042]    The end effector outer casing  516  includes two portions. A distal casing portion  516   a  is attached to the forked distal end  519  in a manner allowing axial movement as described above. A proximal casing portion  516   b  is rotatably connected to the distal casing portion  516   a  such that it can be rotated about the central longitudinal axis of the end effector  502  without moving significantly axially. The proximal casing portion  516   b  includes an inner threaded surface  524  that is complementary to the outer threaded surface  510  of the main body&#39;s outer shaft  508 . And, the proximal casing portion  516   b  preferably includes a textured outer surface  516   c  that provides enhanced friction for gripping the proximal casing portion  516   b  and rotating it (e.g., to engage the inner threaded surface  524  with the outer threaded surface  510  of the main body&#39;s outer shaft  508 ). 
         [0043]    A method of engaging the threaded-plus-bayonet end effector connection system  500  is described with reference to  FIGS. 5A-5C . To engage the end effector  502  to the main body  504 , a user axially inserts the proximal portion of the end effector rod  538  into the distal end of the main body&#39;s outer shaft  508 . The user then rotates the end effector  502  relative to the outer shaft  508  (or vice versa) to align the boss-receiving slots  522  of the end effector rod  518  with the bosses  514  of the actuation rod  506 . Once aligned, the user moves the end effector  502  and the main body  504  axially together such that the distal end of the actuation rod  506  enters the end effector rod&#39;s inner receiving channel  520 , the actuation rod bosses  514  slide into the proximal groove portion  522   a  of each boss-receiving slot  522  of the end effector rod  518 . Next, the user rotates the end effector  402  counterclockwise relative to the outer shaft  408  (or vice versa). This rotation engages the bosses  514  into the distal slot portions  522   b  of the end effector rod  518 . Because each of the distal slot portions  522   b  of the end effector is slightly distally angled, this boss-slot engagement forms a frictional lock as the proximal end of the end effector rod  518  is forced against the actuation rod lip  506   a.  As shown in the illustrated embodiment, this engagement method requires only a small rotational motion after the initial axial engagement. In the illustrated embodiment, the rotation required to lock in the engagement is less than 90°. In other embodiments, including those with more or fewer bosses, the rotation required is less than 360°. Finally, the user rotates the proximal casing portion  516   b  to engage its inner threaded surface  524  with the outer threaded surface  510  of the main body&#39;s outer shaft  508 . Those of skill in the art will appreciate that the male and female bayonet portions described herein may be reversed in orientation in other embodiments, within the scope of the present invention. 
         [0044]    Those of skill in the art will also appreciate that other variants of the surgical device and end effector connector system embodiments described herein may also be practiced within the scope of the present application. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting. It should be understood that the following claims, including all equivalents, are intended to define the spirit and scope of this invention.