Abstract:
An apparatus may serve as a surgical portal for the reception of surgical instruments for use in laparoscopic or similar surgery. The apparatus may include inner and outer tubular elongate members adapted for a longitudinal translation relative to one another to effect a length adjustment of the apparatus. An interface between the two elongate members includes a helical thread providing a mechanism for the translation of the elongate members, and indentations in one of the members provides a locking mechanism for affixing the length.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/044,183 filed on Apr. 11, 2008, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates generally to an apparatus for permitting the introduction of a surgical instrument into a patient&#39;s body cavity in a laparoscopic or similar surgery. In particular, the disclosure relates to a telescoping cannula assembly configured for longitudinal extension and retraction to effect a length adjustment. 
         [0004]    2. Background of Related Art 
         [0005]    A relatively small incision is required for minimally invasive surgical procedures such as laparoscopic, arthroscopic, and endoscopic procedures as compared with conventional open procedures. Small incisions are preferred because they are inherently less traumatic to the body tissue and subject internal organs to a minimum of exposure to contaminants in the outside atmosphere. Thus, small incisions enable shorter hospital stays and faster recoveries with less pain and scarring than is common with the larger incisions required for conventional surgery. 
         [0006]    Minimally invasive surgery is possible due in part to the availability of instruments designed specifically for this purpose. A cannula, for example, is an elongated tube that may be inserted through the small incision made in a body cavity wall of a patient to provide a working conduit between an internal body cavity adjacent an operative site and the environment exterior to the patient. The body cavity is often inflated with an insufflation gas such as carbon dioxide to separate the body cavity wall from vital organs and to provide some space where a distal end of the cannula can safely protrude into the patient below the body cavity wall. 
         [0007]    The length of a cannula is generally selected to span a range of anatomies and consequently a portion of the cannula assembly which remains on the outside of the patient may extend above the body cavity wall to a greater extent than otherwise desired. The cannula assembly may need to extend into deeper regions of the body cavity, e.g., the abdominal cavity, to access remote underlying organs therein. Furthermore, because several instruments of various lengths might be required for a surgical procedure, an instrument may protrude above the cannula assembly to a greater extent than otherwise desired. Accordingly, a need exists for a cannula assembly which facilitates the introduction of surgical instruments to a surgical site, while allowing a longitudinal retraction or extension to effect an adjustment in length. 
       SUMMARY 
       [0008]    The present disclosure describes a surgical portal apparatus which permits a length adjustment to accommodate a range of body cavity wall thicknesses. The apparatus comprises a tubular elongate inner member adapted and sized appropriately for the introduction of a surgical instrument. The elongate inner member has a proximal end, a distal end and a length therebetween, with a portion of the length radially surrounded by a tubular elongate outer member. A length adjustment structure provides an adjustment interface between the elongate inner member and the elongate outer member. The length adjustment structure includes a generally helical thread on at least one of the elongate members and feature on the other for engaging the thread. A length fixation structure includes inter-engaging components for selectively and non-permanently securing a longitudinal position of the elongate inner member within the elongate outer member. 
         [0009]    The inter-engaging components may include a series of indentations arranged in a generally helical pattern corresponding to the generally helical thread. The series of indentations may be disposed on an interior surface of the generally helical thread. The surgical portal apparatus may include a housing at or near the proximal end containing a seal apparatus capable of sealing the apparatus before, during and after the introduction of a surgical instrument. The housing may include a connection for introducing an insufflation gas into the body cavity. The elongate outer member may be positioned distally of the elongate inner member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the detailed description of the embodiments given below, serve to explain the principles of the disclosure. 
           [0011]    PIG.  1  is a side view of a surgical portal apparatus in accordance with the present disclosure inserted through a body cavity wall; 
           [0012]      FIG. 2  is a partial cross-sectional view of the telescoping cannula assembly of  FIG. 1 ; 
           [0013]      FIG. 3A  is an enlarged view of the area of detail identified in  FIG. 2 ; 
           [0014]      FIG. 3B  is a view similar to view  3 A depicting an alternate length fixation structure; and 
           [0015]      FIG. 3C  is a view similar to view  3 A depicting another alternate length fixation structure. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0016]    The attached figures illustrate exemplary embodiments of the present disclosure and are referenced to describe the embodiments depicted therein. Hereinafter, the disclosure will be described in detail by explaining the figures wherein like reference numerals represent like parts throughout the several views. 
         [0017]    The present disclosure contemplates the introduction into a person&#39;s body of all types of surgical instruments including clip appliers, graspers, dissectors, retractors, staplers, laser fibers, photographic devices, endoscopes and laparoscopes, tubes, and the like. All such objects are referred to herein generally as “instruments.” In the drawings and in the description that follows, the term “proximal,” as is traditional, will refer to the direction toward the operator or a relative position on the surgical device or instrument that is closer to the operator, while the term “distal” will refer to the direction away from the operator or relative position of the instrument that is further from the operator. 
         [0018]    Referring initially to  FIG. 1 , a surgical portal apparatus is generally depicted as telescoping cannula assembly  10 . Telescoping cannula assembly  10  includes an elongate outer member  14 , an elongate inner member  18  and a housing  22 . Elongate outer member  14  is positioned through the skin  26  and within a layer of body tissue  28 . Skin  26  and body tissue  28  together define a body cavity wall  30  with a thickness “t.” A distal end  34  of the elongate outer member  14 ,protrudes into an interior body cavity of a patient, and housing  22  remains in an exterior environment. A proximal end  38  of elongate inner member  18  may be rigidly coupled to housing  22  such that there is no relative motion therebetween, and a distal end  40  ( FIG. 2 ) of inner member  18  is telescopically arranged within elongate outer member  14 . Using a length adjustment structure as described in greater detail below, the overall length “L” of telescoping cannula assembly  10  may be adjusted by retracting or extending elongate inner member  18 , for example to accommodate a variance in the thickness “t” of body cavity wall  30 . 
         [0019]    Referring now to  FIG. 2 , telescoping cannula assembly  10  is depicted in partial cross section. Housing  22  includes an insufflation gas valve  44  and internal seal system  46 , which may be capable of permitting the passage of an instrument while preventing insufflation gasses from escaping through a proximal end of telescoping cannula assembly  10  before, during and after introduction of the instrument. Internal seal system  46  may take any form including the form described in U.S. Pat. No. 5,603,702 to Smith et al., filed Aug. 8, 1994, the entire contents of which are hereby incorporated by reference. 
         [0020]    Elongate inner member  18  includes a longitudinal bore  50  defining a passageway adapted for the introduction of an instrument. The distal end  40  and a substantial portion of elongate inner member  18  are radially surrounded by elongate outer member  14 . A length adjustment structure defines the degree to which elongate inner member  18  is nested within elongate outer member  14  and therefore, the overall length L of telescoping cannula assembly  10 . 
         [0021]    The length adjustment structure may include a female thread  52  (shown in phantom) disposed on an outer surface  58  of elongate inner member  18 . A corresponding male protrusion  60  or rib is disposed on an interior surface  62  of elongate outer member  14  and extends into thread  52 . Male protrusion  60  may take the form of a full male thread. Alternatively, male protrusion  60  may comprise one or more narrow tabs appropriately positioned to guide the relative motion of elongate outer member  14  along thread  52 . As seen best in  FIG. 3A , thread  52  includes several interior surfaces  64  for engaging male protrusion  60 . Thread  52  may exhibit a course pitch allowing for large adjustments to be made quickly requiring only a few rotations of either the inner or outer elongate member  18 ,  14 . The overall length of cannula assembly may be adjusted by corresponding rotational movement of inner member  18  and outer member  14 . 
         [0022]    As seen in  FIG. 3B , a length fixation structure may comprise a series of indentations  66  on the exterior surface  58  of elongate inner member  18 . Indentations  66  may be discrete, incrementally spaced notches or serrations arranged along the length of elongate inner member  18 . Male rib  68  may extend into an indentation  66  to non-permanently arrest the relative motion of elongate inner and outer members  14 ,  18 . When sufficient force is applied to either the elongate inner or outer member  14 ,  18  in an axial direction, male rib  68  may be temporarily displaced to move over ridges  70  between indentations  66 . In this way, male rib  68  can act as a pawl engaging a ratchet formed from the series of indentations  66  and ridges  70  to non-permanently fix the overall length “L” of cannula assembly  10 . Male rib  68  may be formed from a flexible material, ball plunger, or other suitable arrangement. Indentations  66  and male rib  68  may encircle elongate inner member or any part thereof. 
         [0023]    Referring now to  FIG. 3C , a length adjustment interface is described that incorporates a length adjustment structure and a length fixation structure. A helical thread  72  wraps around elongate inner member  18 . Helical thread  72  is equipped with a series of internal spaced ridges or detents  74  and indentations (not visible) between ridges  74  arranged along a helical path corresponding to an inner surface  78  of thread  72 . Male protrusion  80  is equipped with male rib or pawl  88  configured to interface with the indentations between ridges  74  in, e.g., a pawl detent arrangement or in the manner described in connection with the embodiment of  FIG. 3B . Male protrusion  80  may alternatively be adapted to engage the indentations between ridges  74  directly. 
         [0024]    The positioning of the indentations may take various forms. For example, the indentations may be positioned in a helical path on the outside surface  58  of elongate inner member  18  rather than on an inside surface  78  of thread  72 . In this case a male rib  88  on the inside surface  62  of elongate outer member may engage the indentations to secure the relative positions of elongate members  14 ,  18 . Also, rather than resembling closely spaced serrations, the indentations may comprise a limited number of strategically placed detents to accommodate the use of standard sized instruments or to accommodate the most typical tissue thicknesses. 
         [0025]    In use, the overall length “L” of telescoping cannula  10  may be adjusted by rotating elongate inner member  18  along thread  72  until elongate inner member  18  reaches a satisfactory longitudinal position within elongate outer member  14 . The engagement of male rib  88  with an indentation may provide a tactile queue that such a position has been achieved. The engagement of male rib  88  is sufficiently robust to prevent any unintended longitudinal migration of elongate inner member  18  under the weight of housing  22  and other forces associated with introducing and manipulating a surgical instrument. 
         [0026]    In drawing figures and the corresponding descriptions above, the male features of the adjustment interface have been associated with the elongate outer member  14  and the female components have been associated with the elongate inner member  18 . However, this convention made for clarity may be reversed and these features may be associated with either elongate member  18 ,  14 . Also, the elongate inner member has been described as fixedly attached to the housing  22  and the elongate outer member movable relative to the housing and elongate inner member. This convention may also be reversed such that the elongate outer member is fixedly attached to the housing and the elongate inner member is movable within the elongate outer member  14 . 
         [0027]    Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims.