Abstract:
A cannula fixation system that allows for easy insertion and removal. A flexible sleeve with corrugations and proximal flange is attached distally to the cannula. The flange serves as a splashguard and a finger retention device. The corrugations have a variable diameter depending upon the tension applied to the proximal flange. The flange is pulled proximally to reduce the diameter of the corrugations for insertion of the cannula. Upon release of the flange, the corrugations expand because of the inherent resiliency of the sleeve to seal against the portal in the patient. The cannula body can be shifted with the sleeve remaining in sealing contact with the portal.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The field of this invention relates to cannulas through which surgical instruments are inserted and more particularly to fixation devices to hold the cannula in one or more positions with respect to the incision in the patient.  
           [0003]    2. Description of the Prior Art  
           [0004]    Endoscopic surgical procedures involve insertion of instruments through incisions or punctures as well as the placement of the scope and associated light source through other incisions or punctures. During such procedures, a variety of instruments are used through one or more cannulas for access to different locations. As a result, the cannula through which the instruments are inserted and manipulated must be shifted to gain better access to the specific location. Additionally, in arthroscopic procedures (a subset of the category of endoscopic procedures), to allow better viewing of the surgical site, the site is kept under a slight liquid flow pressure to facilitate access and to keep body fluids from occluding the scope. For this reason it is advantageous to maintain a seal between the cannula and the body even if the cannula position requires shifting. Allowing the seal to be broken can result in fluids escaping and hitting the surgeon. Apart from a need to have the option of repositioning the cannula after fixation, another objective of the cannula should be simple and reliable insertion or removal. These benefits are found in the present invention of the cannula fixation system.  
           [0005]    Fixation devices have been used in the past on catheters. The purpose of these devices has been to hold the catheter in position, after setting, for the duration of the procedure. An example of a urinary catheter with a corrugated expanding sleeve is shown in U.S. Pat. No. 3,970,090 (Loiacono). This device is intended to be retained in a tubular passageway and, like all catheters is not open at the end to accept surgical instruments. Other examples of passageway catheters with multifold sleeves are U.S. Pat. Nos. 5,827,304 (Hart) and  6 , 254 , 571  (Hart). These two patents show the use of the sleeve to remove occlusive material from a body passage. There are patents showing cannulas with dual fold or dual element sleeves, such as U.S. Pat. Nos. 5,122,122 (Allgood) and  5 , 836 , 913  (Orth et al.) although these devices are difficult to use and not adjustable.  
           [0006]    The following U.S. patents show slots forming strips that expand on compression to anchor but not to seal cannulas or catheters: U.S. Pat. No. 1,621,159 (Evans); U.S. Pat. No. 3,108,595 (Overment); U.S. Pat. No. 3,261,357 (Roberts et al.); U.S. Pat. No. 3,896,804 (Ekbladh et al.); U.S. Pat. No. 3,938,530 (Santomieri); U.S. Pat. No. 4,043,338 (Homm et al.); U.S. Pat. No. 4,608,965 (Anspach et al.); U.S. Pat. No. 4,699,611 (Bowden) and U.S. Pat. No. 5,053,009 (Herzberg). Some patents use spirally cut strips instead of longitudinally oriented strips such as GB 955,490 (Brooke) and U.S. Pat. No. 5,275,975 (Foshee). Yet other US designs involve inflatable fixation devices, such as: U.S. Pat. No. 3,915,171 (Shermeta); U.S. Pat. No. 3,952,742 (Taylor); U.S. Pat. No. 4,077,412 (Moossun); U.S. Pat. No. 4,861,334 (Nawaz); U.S. Pat. No. 5,002,557 (Hasson) and U.S. Pat. No. 5,147,316 (Castillenti). Other US designs employ collet fingers to anchor, such as: U.S. Pat. No. 3,039,468 (Price); U.S. Pat. No. 3,717,151 (Collett) and U.S. Pat. No. 5,445,615 (Yoon). Finally of general interest in the areas of fixation devices for catheters or cannulas are U.S. Pat. No. 4,655,752 (Honkanen et al.)(cannula body with fixed annular ribs); U.S. Pat. No. 5,009,643 (Reich et al.) (threaded cannula body) and U.S. Pat. No. 5,234,455 (Mulhollan) (cannula with distal annular radially extending lip).  
           [0007]    None of the foregoing prior art devices have all the benefits afforded by the present invention which presents a cannula that is easily inserted or removed and whose position can be easily altered while it remains sealingly in contact with the incision in the patient. (The term “incision” will be understood to mean any portal through which the cannula is inserted, regardless of how the portal was created.) These and other advantages and aspects of the present invention will be more readily appreciated by those skilled in the art from a review of the description of the preferred embodiment and the claims which appear below.  
           [0008]    Accordingly, it is an object of this invention to produce a cannula fixation system enabling a user to, with one hand, place a cannula into a portal, secure it within the portal and subsequently adjust the cannula position and re-secure it.  
           [0009]    It is also an object of this invention to produce a cannula fixation system which sealingly secures a cannula in a portal while enabling adjustments of the cannula position within the portal without destroying the seal.  
         SUMMARY OF THE INVENTION  
         [0010]    These and other objects of this invention are achieved by the preferred embodiment disclosed herein which is a cannula which features a fixation system that allows for easy insertion and removal. A flexible sleeve with corrugations and a proximal flange is slidably attached to the cannula. The distal end of the sleeve is fixedly attached near the distal end of the cannula, while the proximal end of the sleeve remains unattached. The flange serves as a splashguard and a finger retention device. The flange is pulled distally to stretch the sleeve and thereby reduce the outer diameter of the corrugations for insertion or movement of the sleeve. Upon release of the flange, the corrugations expand thereby creating a seal against the tissue surrounding the portal in the patient. The cannula body can be shifted longitudinally relative to the sleeve without destroying the sealing contact between the sleeve and the portal. 
       
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a perspective view of the cannula ready for insertion or removal.  
         [0012]    [0012]FIG. 2 is the view of FIG. 1 showing the cannula in a deployed state. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    Referring to FIGS. 1 and 2, the cannula C has a tubular body  10  having a distal end  12  and a proximal end  14 . It has an axial passage  16  that extends from the proximal end  14  to the distal end  12 . Lateral passage  18  extends into passage  16  for connection of a vacuum (or fluid) source, in a known manner. Corrugated sleeve  20  is attached at its distal end  22  to body  10 . This connection can be fixed or adjustable but in the preferred embodiment is preferably fixed. Fixation can be achieved with an adhesive or with ultrasonic welding or other suitable means. The point of attachment is not shown to scale relative to the proximal and distal ends of cannula C. In the preferred embodiment a cannula with an axial passage diameter of approximately 1 cm would have a length L on the order of 8-9 cm for shoulder arthroscopic procedures and the sleeve distal end would then be attached approximately 1 cm away from the cannula distal end  12 . Other sizes of cannulas may be produced for other procedures with appropriate adjustments in sleeve size and placement. The purpose of the connection of the distal end  22  to body  10  is to enable motion of the corrugations of sleeve  20  relative to the cannula to thereby alter the diameter of sleeve  20 . Thus, the point of attachment of end  22  could vary along the length of body  10  and could be adjustable. Once selected, however, the end  22  should be secured to body  10  sufficiently to enable sleeve  20  to be stretched and compressed as will be understood below.  
         [0014]    The sleeve  20  may be color coded for the size of the passage  16  in the body  10 . At its proximal end it has an annular flange  24 , which serves as a finger grip and splashguard. Flange  24  has an internal diameter large enough to accommodate body  10 , so that the flange can easily slide along the body, and an outer diameter sufficient to enable it to serve as a grasping element and a splash shield. Between its distal end at  22  and flange  24 , sleeve  20  is provided with corrugations  26  having ridges  26   a  and grooves  26   b . Sleeve  20  is made of a resilient material such that ridges  26   a  have a normal, unbiased outer diameter D1 (best seen in FIG. 2). Flange  24  may be pulled proximally to stretch the sleeve to thereby decrease the outer diameter of ridges  26   a  to diameter D2, the position shown in FIG. 1, for insertion or removal of the cannula C. The ridges decrease in diameter when the flange  24  is pulled toward proximal end  14  because sleeve  20  is attached to the body  10  at  22 . The individual ridges along the length of sleeve  20  may have equal or varying outer diameters and can be tapered or have a larger diameter between the ends of sleeve  20  than at the ends. The outer surface  27  of sleeve  20  can be textured to promote gripping and sealing. The inner diameter of the grooves  26   b  is variable as the sleeve is stretched, but should always allow the sleeve proximal end to slide relative to the cannula body.  
         [0015]    The cannula body  10  is preferably a plastic material of sufficient column strength so that it does not kink or buckle during insertion or use. The sleeve  20  is preferably rubber, a resilient elastomeric material or some other biocompatible material with memory so that it goes back to a neutral shape having a larger diameter D1 after the flange  24  is released and the body  10  is in proper position with a portal. Clearly, the portal size must be smaller than diameter D1 to enable the cannula to be “locked” in place. The tendency for the ridges  26   a  to spring outwardly on release of flange  24  helps to maintain the seal in the portal as well as the position of the body  10 . The attachment at  22  is preferably with an adhesive, although other types of fixed or movable attachments are contemplated. The shape, size and number of corrugations  26  can be varied according to the sealing and fixation needs for the size of the opening or passage  16  in cannula C. Similarly the resiliency and flexibility of the material of sleeve  20 , and the design (thickness, etc.) of the corrugations may vary depending upon the work site or intended use of the cannula. Various colors can be used for the sleeve  20  consistent with the size of the body  10  or other parameters. Preferably, the flange  24  should extend sufficiently radially outward to make it easy to grip with a fingertip.  
         [0016]    Those skilled in the art can see that the cannula C of the present invention has the advantage of being easily inserted and removed. Once cannula C is inserted and the flange  24  is released, ridges  26   a  expand radially for an anchoring and sealing grip. Thereafter a fluid seal is maintained between the portal and the corrugations of the sleeve. This seal enables the body  10  to be repositioned with respect to the sleeve  20  while the corrugations  26  maintain the anchoring function and the sealing function. That is, cannula C may be shifted inwardly and outwardly without moving the sleeve&#39;s point of contact with the portal. The corrugations inherently provide the cannula with the ability to slidably move longitudinally relative to the portal. The ridges and grooves in contact with the portal are held in place by the portal. Any movement of the cannula distal end away from the portal (i.e. pushing the cannula in) will tend to stretch the distal end of the sleeve. That is, the ridges of the corrugations at the distal end will become further apart. Similarly, movement of the cannula distal end toward the portal (i.e. pulling the cannula out) will tend to compress the distal end of the sleeve. Also, the cannula may be tilted relative to the portal axis to allow access to another site without splashing the surgeon because the seal remains intact. This frequently occurs in endoscopic surgery as access to various portions of the work site is necessary during the procedure. To do this the body  10  is simply shifted without a pull force on the flange  24 . The shifting can occur in either one of two opposite directions. The flange  24  also serves as a splashguard if the seal in the incision around the corrugations  26  is broken for any reason.  
         [0017]    The connection of the sleeve to the cannula may be accomplished without adhesive. For example, the cannula body may be made with a tapered distal end and the sleeve may be made with a fixed diameter, resilient distal end. If the diameter of the sleeve distal end is smaller than the largest diameter of the taper then the sleeve will effectively be fixed to the cannula when the flange is pulled proximally If the sleeve distal end is resilient, it will in effect be secured to the cannula by frictional engagement. In such an embodiment the sleeve could be made separately from the cannula and could be made to fit a variety of cannula sizes.  
         [0018]    While corrugations  26  are shown in the preferred embodiment, it will be understood that sleeve  20  could comprise a “smooth” outer surface devoid of ridges and grooves. That is, a sleeve body could be biased so as to be capable of adopting an unbiased, large diameter and a stretched or biased small diameter. Texturing the “smooth” outer surface would facilitate the frictional engagement of the sleeve with the portal. Thus, the term “corrugated” as used herein is intended to encompass such alternatives.  
         [0019]    It will be understood by those skilled in the art that numerous improvements and modifications may be made to the preferred embodiment of the invention disclosed herein without departing from the spirit and scope thereof.