Abstract:
A surgical access device for permitting introduction of instrumentation within tissue, includes an elongate member defining a longitudinal axis and proximal and distal ends, a first peripheral projection disposed on an outer wall of the elongate member and defining a proximal ledge dimensioned to resist movement of the elongate member in a first longitudinal direction corresponding to a withdrawal direction of the elongate member with respect to the tissue, a second peripheral projection disposed on the outer wall of the elongate member proximal of the first peripheral projection and defining a distal ledge dimensioned to resist movement of the elongate member in a second longitudinal direction corresponding to an insertion direction of the elongate member with respect to the tissue whereby the first and second peripheral projections cooperate to retain the elongate member within the tissue.

Description:
This application claims priority from provisional application No. 60/124,855, Mar. 17, 1999. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to surgical instruments for performing laparoscopic and endoscopic surgical procedures, and, more particularly, relates to a self-retaining cannula assembly incorporating a novel retention mechanism for securing the cannula within an incision in a patient&#39;s body while preventing over insertion of the cannula during application. 
     BACKGROUND OF THE INVENTION 
     In laparoscopic and endoscopic surgical procedures, a small incision or puncture is made in the patient&#39;s body to provide access for a tube or a cannula device which is inserted into the patient&#39;s body to permit for viewing of the surgical site or for the insertion of instruments used in performing the surgical procedure. Typically, a trocar device is used to penetrate the body wall, whereby a sharpened point or tip of the trocar assembly creates the path to the surgical site. A cannula is provided as part of the trocar assembly such that when the pointed piercing mechanism is removed, the cannula remains in place to maintain access to the surgical site. Several incisions may be made to provide numerous access ports to the surgical objective, and once the cannulas are in place, various surgical instruments such as scissors, dissectors, retractors or the like, may be inserted by a surgeon to perform the surgery. Typically, a scope device is used to view the area directly, or a miniature camera is used to display the surgical site on a video monitor in the operating room. 
     In order to maintain the cannula within the incision, it has been known to provide various mechanisms such as external sleeves, expandable members, etc. which engage the tissue surrounding the incision to prevent undesired removal of the cannula. However, such known mechanisms are generally complex in nature. Moreover, these mechanisms often are potentially invasive to the surrounding tissue thereby increasing the likelihood of undesired tissue tear which consequently increases patient trauma and recovery time. Another deficiency in known cannulas of this type concerns the lack of structure to prevent over insertion of the cannula during application within the surgical site. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a cannula including a novel tissue gripping arrangement which supports the cannula in an incision in the patient&#39;s body to provide access to the abdominal cavity during, for example, a laparoscopic or endoscopic surgical procedure. In a preferred embodiment, the cannula includes tissue gripping elements which are arranged to facilitate insertion of the cannula within the cavity by, for example, minimizing insertion force required to advance the cannula relative to the operative site while also restricting removal of the cannula by increasing the withdrawal force required to remove the cannula. Furthermore, several of the tissue gripping elements are specifically adapted to engage the tissue upon insertion of the cannula a predetermined distance to thereby minimize the potential of overinsertion of the cannula relative to the operative site thereby avoiding potential consequences to underlying tissue, organs, etc. Several embodiments of the cannula with the tissue gripping elements are disclosed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various embodiments are described with reference to the drawings, wherein; 
     FIG. 1 is a side view of a trocar assembly incorporating a cannula having external fixation structure provided thereon constructed in accordance with the present disclosure; 
     FIG. 1A is an isolated view of a fixation member of the cannula of FIG. 1; 
     FIG. 2 is a partial side view illustrating a second embodiment of an external fixation structure incorporated within a cannula; 
     FIG. 3 is a partial side view illustrating a third embodiment of the external fixation structure; 
     FIG. 4 is a partial side view illustrating a further embodiment of the external fixation structure; 
     FIG. 5 is a partial side view of a further embodiment of a cannula having external fixation structure provided thereon which is similar to that provided on the embodiment of FIG. 1; 
     FIG. 6 is a partial side view of the distal end portion of a cannula illustrating another embodiment of a fixation structure pattern; 
     FIG. 7 is a partial side view of the distal end portion of a cannula having a further external fixation structure pattern formed thereon; 
     FIG. 8 is a side view of a further embodiment of the external fixation structure in the form of a helical thread; 
     FIG. 9 is a side view of a further alternative embodiment of a cannula which is similar to the embodiment of FIG. 2; 
     FIG. 10 is a partial cross-sectional view of the fixation member of the embodiment of FIG. 9; 
     FIG. 11 is a longitudinal cross-sectional view of a portion of a cannula sleeve having a further alternative external fixation structure design; 
     FIG. 12 is a longitudinal cross-sectional view of a further cannula embodiment shown during insertion of the cannula through a patient&#39;s body wall; and 
     FIG. 13 is a view similar to FIG. 12, which shows an external fixation structure deployed to a retaining position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is particularly suited for use with surgical access devices including cannulas, catheters, endoscopic tubes, sheaths or the like. Such access devices are typically utilized in conjunction with a surgical procedure for introducing/withdrawing fluids or to permit insertion of additional instrumentation required to satisfactorily perform the surgical procedure. The following description of the present invention will be focused on its use with a surgical trocar or cannula assembly; however, it is appreciated that the present invention has application in any of the surgical access devices of the type listed hereinabove. 
     In the following description, as is traditional, the term “proximal” refers to the portion of the instrument closest to the operator while the term “distal” refers to the portion of the instrument remote from the operator. 
     Referring to the drawing figures wherein like reference numerals represent similar or identical elements and initially to FIG. I, there is illustrated a surgical trocar assembly  10  which incorporates the principles of the present invention. One suitable trocar assembly is disclosed in commonly assigned U.S. Pat. No. 4,601,710 to Moll, the contents of which are incorporated herein by reference. The presently disclosed cannula embodiments may be utilized in virtually any trocar assembly of the type having an outer sheath or cannula into which an obturator is inserted to provide access to a surgical site, particularly, in minimally invasive surgical procedures such as those performed, for example, endoscopically or laparoscopically. Briefly, the presently disclosed cannula embodiments provide numerous alternative designs for providing integral tissue gripping structure. Such structure is particularly advantageous in that it increases the retaining characteristics of a cannula within a body wall and also minimizes the potential of over insertion of the cannula. The structure also eliminates the need for additional separate anchoring mechanisms. 
     With reference to FIGS. 1 and 1A, trocar assembly  10  includes cannula  100  and obturator  1000  which is positionable in the cannula  100 . Obturator  1000  includes an obturator housing  1002  and an obturator portion  1004  having pointed obturator tip or blade  1006  for penetrating tissue. In use, subsequent to insertion of trocar assembly in the tissue site, obturator  1000  is removed from cannula  100  leaving the cannula  100  in the tissue to serve as a portal for introduction of instrumentation. 
     Cannula  100  includes a cannula housing  102  and a cannula sleeve  104  connected to the housing  102  and extending distally therefrom. Cannula sleeve  104  defines longitudinal axis “a” and has an outer wall  106  which defines an inner longitudinal opening therein. Cannula  100  includes a first proximal series  110  of external fixation members such as rings  112  which taper outwardly away from the surface of cannula  100  in a generally distal direction. In this manner, a generally proximal oriented surface  112   a  is formed at an oblique angle relative to a longitudinal axis of cannula  100  and a distal facing planar surface  112   b  is formed transverse to a longitudinal axis of cannula  100 . A second distal series  114  of external fixation members such as rings  116  are disposed distal of ring series  110 . Rings  116  taper inwardly towards the surface of cannula  100  in a generally distal direction and form proximally facing planar surface  116   a  which is preferably transverse to the longitudinal axis “a” and distally oriented angled surface  116   b  as best depicted in FIG.  1 A. 
     The above-noted structural arrangement provides for retention of cannula  100  in the body tissue due to the oppositely facing rings  112  and  116 . Additionally, upon insertion, angled surfaces  116   b  of distal ring series  114  helps maintain relative ease of insertion of cannula  100 . Preferably, angled surfaces  116   b  define an angle “x” ranging from about 10° to about 60° relative to the longitudinal axis “a” of cannula sleeve and, more preferably, about 45° relative to the longitudinal axis “a”. Such arrangement of angled surface  116   b  minimizes the insertion force needed to advance cannula  100  in an insertion direction, indicated as arrow I, within the tissue “t”. 
     Cannula  100  is continually advanced to a position whereby proximal ring series  110  reaches the tissue. At this juncture, planar surfaces  112   b  of series  112  engage the tissue. Planar transverse surfaces  112   b  effectively substantially increase the insertion force required to further insert cannula  100  thereby minimizing the potential of “over insertion” of the cannula  100 . Moreover, rings  112  provide a tactile indication to the user that the cannula  100  has been sufficiently inserted to access the abdominal cavity and any further inserting movement may increase the potential of contact of the cannula with underlying tissue, organs, etc. When cannula  100  is situated with respect to the tissue, the opposing planar surfaces  112   b  of ring series  110  and  116   a  of ring series  114  serve as ledges to maintain cannula  100  at a fixed position within the tissue site, i.e., planar surfaces  112   b  resist movement of the cannula  100  in the insertion direction “I” while planar surfaces  116   a  resist movement of the cannula in the withdrawal direction “W”. 
     Referring to FIG. 2, a proximal portion of cannula  200  features a series  210  of chevron or V-shaped raised surfaces  212 , the apexes  214  of which point proximally. A distal portion of cannula  200  features a series  216  of chevron shaped raised surfaces  218 , the apexes  220  of which point toward the distal end of cannula  200 . With this arrangement, the insertion force is further reduced due to the streamline profile presented by the distal series  216 . In all other respects, cannula  200  is similar to the cannula  100  of FIG.  1 . 
     Referring to FIG. 3, a proximal half of cannula  300  features a series  310  of disjoined chevron shaped raised surfaces formed of disjoined segments  312   a  and  312   b.  A distal portion of cannula  300  features a series  314  of disjoined chevron shaped raised surfaces formed of segments  316   a  and  316   b.  This arrangement further reduces the insertion force required to insert the cannula by providing a longitudinal slot  320  as defined by the open apexes of series  310 ,  314  to which tissue displaced by the cannula during insertion may be received and pass. 
     Referring to FIG. 4, cannula  400  is the same as cannula  300  except that the proximal and distal raised surfaces  402 , 404  do not extend beyond the outer diameter of cannula  400 , as shown by proximal and distal outer wall portions  406 ,  408 , respectively, i.e., the surfaces are confined within the outer boundary of the cannula sleeve. 
     Referring to FIG. 5, cannula  500  is very similar to cannula  100  of FIG. 1 with two main exceptions. The first is that proximal and distal series  510 ,  514  are respectively displaced a predetermined distance. This provides a central tissue retaining region  512  between the two series  510 ,  514  which receives the proximal and distal surfaces of the tissue, such as, for example, the abdominal tissue, i.e., inclusive of the tissue between the epidermis and the peritoneal cavity lining. 
     Referring to FIG. 6, cannula  600  is similar to cannula  200  except that raised chevron shaped portions  616  are formed within the boundaries of the outer diameter of cannula  600 , i.e., the distance “e” across the chevron portions  116  is substantially equal to or less than the outer diameter of the cannula sleeve  602 . Additionally, cannula  600  is provided with a beveled distal end  615  which has a chamfer  617  provided thereon. Chamfer  617  facilitates the initial insertion of cannula within the tissue site. 
     Referring to FIGS. 7-11, various alternative embodiments of cannulas are shown having different external fixation structure. With reference to FIG. 7, cannula  700  is provided with a series of sinusoidal shaped raised portions  717 . Cannula  800  is provided with helical threads  816  thereon, as shown in FIG.  8 . Cannula  900  is similar to cannula  200  of FIG. 2, except cannula  900  illustrates that different numbers of raised portion elements  912 ,  916  may be provided in the proximal and distal series  910 ,  914 , respectively. FIG. 10 illustrates the cross-sectional shape of distally oriented chevron shaped raised portions  916  of FIG.  9 . Raised portions  916  have angled surfaces  916  a and  916   b.  Surface  916   a  is angled such that it forms a greater angle of attack with the tissue proximal thereto and surface  916   b  provides a lesser angle of attack than surface  916   a,  with the distal tissue. In this embodiment, the proximal surface  916   b  is not transverse to the axis, but, may range from about 60°-90°. For proximal raised surface  912 , the opposite relationship to that described in connection with raised surface  916  would apply. 
     Referring to FIG. 11, cannula  1000  is provided with a greater number of series  1002 ,  1004 ,  1006 ,  1008 , and  1010  of raised portions wherein adjacent series have raised portions oriented in the opposite direction. Additionally, the proximal and distal surfaces of each raised portion is curved or arcuate. 
     Referring to FIGS. 12 and 13, cannula  1100  is provided with a tissue retention sleeve member  1110  coaxially mounted about the cannula sleeve  1105 . Retention sleeve member  1110  may be fabricated from an elastomeric material and preferably formed, e.g., by injection molding techniques to define varying ridges  1112 ,  1114  when retention member is in an at rest condition, as shown in FIG.  13 . Preferably, retention member  1110  is secured at a distal end to cannula  1100  by conventional means and is provided with finger levers  1116 ,  1118  at a proximal end. Finger levers  1116 , 1118  may be formed of a rigid polymeric material or a suitable metal and secured to the proximal end of sleeve member by conventional means, or may be integrally formed with the sleeve member. In use, finger levers  1116 ,  1118  are retracted upon insertion of cannula  1100  through the body wall of the patient, as shown in FIG.  12 . This stretches retention member  1110  thereby smoothing out ridges  1112 ,  1114 . Once the cannula is situated in the desired position through the body wall, levers  1116 ,  1118  are released permitting ridges  1112 ,  1114  to assume their initial unactuated position thereby acting to resist proximal or distal movement of cannula  1100  with respect to the body wall. Alternatively, instead of being molded from an elastomeric material, retention member  1110  may be formed from one or more shape memory materials to achieve the above-noted results. 
     While the invention has been particularly shown and described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various modifications in form and detail may be made therein without departing from the scope and spirit of the invention. Accordingly, modification to the preferred embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit and scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown, but it is to be accorded the widest scope consistent with the principles and features disclosed herein.