Abstract:
A medical assembly includes a cannula and a scaling cap releasably coupled to the cannula. The cap includes a body and a sealing member integrally molded with the body to form a fluid-tight seal between the cap and cannula. The cap includes a member defining an opening for passage of a medical instrument therethrough in a fluid-tight manner. The member includes a first portion surrounding the opening and being thickened to limit tearing of the first portion, and a second portion surrounding the first portion being tapered down in thickness toward the first portion to increase flexibility of the member. The assembly includes a shaft receivable in a lumen defined by an inner surface of the cannula. The shaft includes a protrusion and the inner surface further defines a protrusion receiving formation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of U.S. patent application Ser. No. 10/805,380 filed on Mar. 22, 2004. The disclosure of this prior application is incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD  
       [0002]     This invention relates to a cannula used for arthroscopic, endoscopic, or laproscopic surgery.  
       BACKGROUND  
       [0003]     A cannula can be inserted into a portal in a tissue in cooperation with an obturator or trocar that is received in the cannula and has a tapered end that extends beyond the end of the cannula. Once the cannula has been inserted into the tissue, the obturator or trocar is removed and surgical instruments can be passed through the cannula into tissue to perform arthroscopic, endoscopic, or laproscopic surgery.  
       SUMMARY  
       [0004]     According to one aspect of the invention, a medical assembly includes a cannula and a sealing cap releasably coupled to the cannula. The cannula and cap are configured to form a fluid-tight seal therebetween without the use of an additional element. Embodiments of this aspect of the invention may include one or more of the following features: The cannula has a wall with an inner surface defining a lumen, and the assembly further includes a shaft receivable in the lumen. The shaft includes a protrusion and the inner surface further defines a protrusion receiving formation, e.g., a slot.  
         [0005]     The cap includes a body and a sealing member integrally molded with the body. The sealing member is, e.g., chemically bonded with the body. The cannula includes an annular shoulder and the sealing member includes an annular projection that is compressed against the annular shoulder to form the fluid-tight seal. The cannula defines a slot, e.g., a J-shaped slot, and the cap has a projection receivable in the slot to releasably couple the cap to the cannula.  
         [0006]     The cap includes a member defining an opening for passage of a medical instrument therethrough in a fluid-tight manner. The member includes, e.g., a first portion surrounding the opening that is thickened to limit tearing of the first portion, and a second portion surrounding the first portion that is tapered down in thickness toward the first portion to increase flexibility of the member. According to another aspect of the invention, a medical assembly includes a cannula and a sealing cap releasably coupled to the cannula. The cap includes a body and a sealing member that is integrally molded with the body and configured to form a fluid-tight seal with the cannula.  
         [0007]     According to another aspect of the invention, a medical assembly includes a shaft with a protrusion, and a cannula having a wall with an inner surface defining a lumen for receiving the shaft. The inner surface defines a protrusion receiving formation, e.g., a slot extending from a proximal end of the cannula. Embodiments of this aspect of the invention may include one or more of the following features. The shaft includes a second, opposing protrusion and the inner surface defines a second, opposing protrusion receiving formation, e.g., a second slot. The second protrusion receiving formation extends from the proximal end of the cannula. The lumen has, e.g, a constant diameter or is tapered.  
         [0008]     According to another aspect of the invention, a medical cannula includes a wall with an inner surface defining a lumen. The inner wall defines a protrusion receiving formation, e.g., a slot, extending from a proximal end of the cannula.  
         [0009]     Embodiments of this aspect of the invention may include one or more of the following features. The inner surface defines a second, opposing protrusion receiving formation, e.g., a second slot. The second protrusion receiving formation extends from the proximal end of the cannula. The wall has an outer surface defining an outer slot, e.g., a J-shaped slot, and a second, opposing outer slot, e.g., a second J-shaped slot. The medical cannula further includes an annular shoulder coupled to the wall for forming a fluid-tight seal with a cap. The wall has an outer surface that is threaded. The lumen has, e.g, a constant diameter or is tapered.  
         [0010]     According to another aspect of the invention, a sealing cap includes a body for releasable attachment to a medical cannula and a sealing member integrally formed with the body and configured to form a fluid-tight seal with the cannula without the use of an additional element.  
         [0011]     Embodiments of this aspect of the invention may include one or more of the following features. The sealing member is, e.g., chemically bonded with the body. The sealing member includes an annular projection that is compressible against the medical cannula to form the fluid-tight seal. The cap includes a projection for removably connecting the cap to the cannula. The cap includes an outer seal disposed over the body. The outer seal defines an opening for passage of a medical instrument therethrough in a fluid-tight manner. The outer seal includes a first portion surrounding the opening that is thickened to limit tearing of the first portion, and a second portion surrounding the first portion that is tapered down in thickness toward the first portion to increase flexibility of the member. The cap further includes an inner seal disposed within the outer seal. The inner seal includes an opening for passage of the medical instrument therethrough in a fluid tight manner.  
         [0012]     According to another aspect of the invention, a seal includes a member defining an opening for passage of a medical instrument therethrough in a fluid-tight manner. A first portion of the member surrounds the opening and is thickened to limit tearing of the first portion. A second portion of the member surrounds the first portion and is tapered down in the thickness toward the first portion to increase flexibility of the member.  
         [0013]     According to another aspect of the invention, a shaft includes an elongated body receivable in a medical cannula. At least two opposed protrusions extend from the body and are configured to mate with respective protrusion receiving formations in the cannula.  
         [0014]     According to another aspect of the invention, a medical assembly includes a means for forming a channel for inserting a surgical instrument into a tissue, and a means for forming a fluid-tight seal with the means for forming a channel.  
         [0015]     According to another aspect of the invention, a method includes inserting a cannula into tissue, and removing a sealing cap from the cannula as a single unit without leaving a loose element behind. Embodiments of this aspect of the invention may include one or more of the following features: removing tissue through the cannula after removing the sealing cap, and reattaching the cap to the cannula while the cannula remains in the tissue.  
         [0016]     Advantages of the invention may include one or more of the following. The integral sealing member allows the cap to be removed from the cannula without the risk of the sealing member being separated from the cap. The integral sealing member also allows the cap to be reattached to the cannula without distorting the sealing member. The protrusions on the shaft and the corresponding protrusion receiving formations in the cannula facilitate the coupling of the shaft to the cannula such that a user can apply a torque to the shaft to turn the cannula. The thickened portion and the tapered portion of the outer seal facilitate the insertion of large surgical instruments through the cannula in a fluid-tight manner.  
         [0017]     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a side view of a medical assembly shown advanced into tissue.  FIG. 2A  is a side view of a cannula of the assembly of  FIG. 1 .  
         [0019]      FIG. 2B  is a cross-sectional view of the cannula of  FIG. 2A  along line  2 B- 2 B.  
         [0020]      FIG. 3  is an end view of the cannula of  FIG. 2  along line  3 - 3 .  
         [0021]      FIG. 4  is a cross-sectional view of the removable sealing cap of the assembly of  FIG. 1 .  
         [0022]      FIG. 5  is an end view of the cap of  FIG. 4  along line  5 - 5 .  
         [0023]      FIG. 6  is a perspective view of the cap of  FIG. 4 .  
         [0024]      FIG. 7  is a perspective view of the cannula and removable cap of the assembly of  FIG. 1  shown with the cap removed from the cannula.  
         [0025]      FIG. 8  is a cross-sectional view of the cannula and removable cap of the assembly of  FIG. 1  shown with the cap coupled to the cannula.  
         [0026]      FIG. 9  is a side view of an obturator of the assembly of  FIG. 1 .  
         [0027]      FIG. 10  is a perspective view of the cannula and obturator of the assembly of  FIG. 1  shown without the cap.  
         [0028]      FIG. 11  is a cross sectional view of the assembly of  FIG. 1  along line  11 - 11 .  
     
    
     DETAILED DESCRIPTION  
       [0029]     Referring to  FIG. 1 , a medical assembly  10  includes a threaded cannula  20 , a sealing cap  40  removably coupled to cannula  20 , and a shaft, e.g., a trocar or obturator  80 , which is received within cannula  20  and cap  40 . Obturator  80  includes a tapered, threaded distal end  82  that extends beyond a distal end  27  of cannula  20 , and a proximal handle  84  that abuts against cap  40 . Obturator  80  is coupled to cannula  20 , as described below, such that turning proximal handle  84  of obturator  80  turns cannula  20  to insert cannula  20  into tissue  90 . When coupled, cap  40  and cannula  20  form a fluid-tight seal without the use of an additional sealing element, e.g., an O-ring, such that cap  40  can be removed from and re-coupled to cannula  20  by the user without the possibility of losing or dropping such an additional sealing element. The removal of cap  40  from cannula  20  permits, e.g., the removal of large pieces of tissue through cannula  20 .  
         [0030]     Referring to  FIGS. 2A, 2B , and  3 , cannula  20  includes a proximal portion  22 , a stopcock portion  28 , a threaded distal portion  25 , and tapered distal end  27 , with a longitudinal bore or lumen  30  extending the length of cannula  20 . Proximal portion  22  has a cylindrical wall  21  with mating features  32 ,  34  formed in outer and inner surfaces  33 ,  35 , respectively, of wall  21 . Mating features  32  are, e.g., opposing J-shaped slots for releasably locking cap  40  to cannula  20 , as discussed below. Mating features  35  are, e.g., opposing protrusion receiving formations, such as opposing longitudinal slots  34  for receiving corresponding projections on obturator  80 , as discussed below. Between proximal portion  22  and stopcock portion  28  is an annular shoulder  29  for forming a fluid-tight seal with cap  40 , as discussed below. Stopcock portion  28  includes a cylindrical portion  23  defining a section of bore  30 , and a stopcock  26  in communication with bore  30  for aspirating fluid into bore  30  or for applying suction to bore  30 . Stopcock  26  includes a port  36  for attachment to a source of fluid aspiration or suction and a manually actuatable valve  38  for controlling the amount of fluid flow or suction.  
         [0031]     Distal threaded portion  25  of cannula  20  includes threads  24  that facilitate inserting cannula  20  into tissue  90  by lifting the skin as the cannula is inserted into tissue  90 . Threads  24  also limit cannula  20  from pulling out of tissue  90  once cannula  20  has been inserted. Tapered distal end  27  also facilitates inserting cannula  20  into tissue  90  by gradually expanding the size of a portal  92  ( FIG. 1 ) in tissue  90 .  
         [0032]     Distal end  27  has a length of approximately 2.5 mm and is tapered at an angle of approximately  15  degrees from the center line, with the length and taper angle chosen for manufacturability. Distal threaded portion  25  has a length of approximately 40 to 90 mm, an outer diameter of approximately 4.5 to 12 mm, with a thread depth of approximately 0.5 to 1.5 mm, a thread angle of approximately 60 degrees, and approximately 0.17 threads per mm. The length is selected according to the depth of the tissue being accessed. Cylindrical portion  23  of stopcock portion  28  has a length of approximately 13.5 mm and an outer diameter of approximately 9 mm. Proximal portion has a length of approximately 5 mm and an outer diameter of approximately 11 mm, to facilitate mating with cap  40 , as discussed below. Longitudinal bore  30  has a length of approximately 60 to 105 mm and a diameter of approximately 2.5 to 10 mm. The length of bore  30  varies according to the length of distal threaded portion  25 . Longitudinal bore  30  and distal threaded portion  25  each has a constant diameter or is tapered, e.g., at an angle of approximately 0.125 to 2 degrees, to facilitate manufacturing by molding. Longitudinal slots  34  each have a length of approximately 6.5 mm and a width of approximately 2 mm to facilitate mating with wings of obturator  80 , as described below.  
         [0033]     Referring to  FIGS. 4-6 , cap  40  is assembled from three components: a mating member or body  44 , an inner seal  70 , and an outer seal  60 . Mating member  44  has an inner wall  41  defining an opening  46  therethrough for receiving a surgical instrument, and a pair of projections  48  extending from wall  41  into opening  46 . Projections  48  are sized and configured to interlock with J-shaped slots  32  defined in proximal portion  22  of cannula  20 . As shown in  FIGS. 7 and 8 , cap  40  is coupled to cannula  20  by aligning projections  48  with J-shaped slots  32 , pushing cap longitudinally in the direction of arrow  47  and then turning cap  40  in the direction of arrow  49  to lock cap  40  to cannula  20 . Cap  40  will then lock itself in place in J-slots  32  by moving slightly in the direction opposite to arrow  47  due to the expansion of a compressed sealing member  50  (discussed below). Cap  40  is removable from cannula  20  by pushing cap  40  in the direction of arrow  47  to compress sealing member  50 , turning cap  40  in a direction opposite to the direction of arrow  49  and pulling cap  40  in a direction opposite to the direction of arrow  47 .  
         [0034]     Mating member  44  includes a locking ring  42  having a plurality of knurls  43 , which facilitate grasping cap  40  when coupling cap  40  to cannula  20  or removing cap  40  from cannula  20 . Two of knurls  43  are enlarged knurls  45  aligned with projections  48 , to facilitate aligning projections  48  with J-shaped slots  32 . Mating member  44  is made of a material having a strength similar to the strength of cannula  20 . For example, cannula  20  is made of a plastic material, such as polyester, having a tensile yield stress of approximately 45 MPa, while mating member  44  is made of a plastic material, such as acrylonitrile butadiene styrene (ABS) 2620 made by Dow Chemical, located in Midland, Mich., and having a tensile yield stress of approximately 41 MPa.  
         [0035]     Mating member  44  includes a ring-shaped sealing member  50  that is integrally molded as a component of mating member  44 , such that mating member  44  and sealing member  50  are a unitary piece. Sealing member  50  is composed of an elastomeric material that is chemically bonded with mating member  40 . For example, sealing member  50  is composed of Versaflex® OM-9-802CL, manufactured by GLS Corporation of McHenry, Ill. Locking ring  42  has a flat face  58  with an indent  59  in which sealing member  50  is located. Sealing member  50  extends beyond flat face  58  to form an annular projection  52 . Sealing member  50  also includes opposing lateral extensions  57  that facilitate molding sealing member  50  into mating member  44 . As shown in  FIG. 8 , when cap  40  is coupled to cannula  20 , sealing member  50  abuts against annular shoulder  27  of cannula  20 , and annular projection  52  is compressed to form a fluid-tight seal between cap  40  and cannula  20 . Because sealing member  50  is an integrally molded component of mating member  44 , cap  40  can easily be coupled to and decoupled from cannula  20  without sealing member  50  becoming separated from cap  40  and dropped or misplaced.  
         [0036]     Inner wall  41  of mating member  44  defines two annular grooves  54  and  56 , for receiving inner seal  70  and outer seal  60 , respectively, in a snap-fit. Inner seal  70  includes a middle section  77  defining a diagonal slit  78  for passing a surgical instrument therethrough, a wall  72  defining an open region  71  for receiving the surgical instrument, and an annular depending skirt  74  defining an open region  73  and including an inwardly projecting rib  76 . Inner seal  70  snap-fits over mating member  44  with mating member  44  in open region  73  and inwardly projecting rib  76  received in annular groove  54 , thus forming a fluid tight seal therebetween. Slit  78  permits surgical instruments to be passed through top wall  72  of inner seal  70  while limiting fluid leakage from cap  40 .  
         [0037]     Outer seal  60  includes a wall  61  and an annular depending skirt  62  defining an open region  69  and including an inwardly projecting rib  63 . Outer seal  60  snap-fits over inner seal  70  and over mating member  44  with inner seal  70  in open region  69  and inwardly projecting rib  63  received in bottom annular groove  56 , thus forming a second fluid tight seal with mating member  44 .  
         [0038]     Inner seal  70  and outer seal  60  are composed of an elastomeric material, such as 30-50 durometer liquid injection molded silicone. Wall or member  61  of outer seal  60  includes an inner ring  64  defining an aperture  65  therethrough, a tapered ring  66  surrounding inner ring  64 , and a peripheral ring  67  surrounding tapered ring  66 . Peripheral ring  67  has a constant thickness T 1 , except for the region of chamfered surface  79 . Tapered ring  66  tapers from thickness T 1  to a thickness T 2  that is less than T 1 . Inner ring  64  is thickened along the outer side of seal  60  to form a reinforcing rib  68 , such that inner portion has a thickness T 3  that is greater than T 2  and less than T 1 . For example, T 1  is approximately 2.5 mm, T 2  is approximately 1 mm, and T 3  is approximately 1.5 mm. Tapered ring  66  is tapered on the outer surface of seal  60  at an angle of approximately 6 degrees over a length L 1  of approximately 6 mm. Tapered ring  55  is tapered on the inner surface of seal  60  at an angle of approximately 10 degrees. Reinforcing rib  68  has a length L 2  of approximately 1.5 mm. Aperture  65  allows surgical instruments to be passed through outer seal  60  while maintaining a seal to limit fluid leakage from cap  40 . Tapered ring  66  increases the flexibility of outer seal  60  to allow introduction of a surgical instrument therethrough while thickened reinforcing rib  68  limits tearing of outer seal  60 .  
         [0039]     Referring to  FIG. 9 , obturator  80  includes distal end  82 , an intermediate portion  83 , an elongated body or shaft portion  85 , and proximal handle  84 . Handle  84  includes a plurality of cut-outs  81  that make handle  84  lighter in weight. Intermediate portion  83  has a diameter D 2  that is the same as or slightly less than the diameter of bore  30  in order to form a seal that inhibits tissue from entering bore  30  while obturator  80  and cannula  20  are being inserted into tissue. Shaft portion  85  has a diameter D 1  that is the same as or less than the diameter of cannula bore  30 , in order reduce the weight of obturator  80  and to limit the stretching of outer seal  60  in cap  40  when shaft portion  85  is passed through cap  40 . Shaft portion  85  has a distal portion  86  including a plurality of lateral flanges  87  that taper proximally in diameter from D 2  to D 1  for a smooth transition between the different diameters of intermediate portion  83  and shaft portion  85 . Distal end  82  tapers from diameter D 2  of intermediate portion  83  to a distal point  88  to facilitate enlarging portal  92  ( FIG. 1 ) in tissue  90 . Distal end  82  is threaded to cooperate with threads  24  on cannula  20  to facilitate inserting cannula  20  into tissue  90 .  
         [0040]     Referring also to  FIGS. 10 and 11 , shaft portion  85  includes opposed lateral wings or protrusions  89  that are sized and configured to be received in longitudinal slots  34  in cannula  20  when obturator  80  is inserted into cannula  20 . Lateral wings  89  releasably couple obturator  80  to cannula  20  so that when obturator  80  is rotated by turning handle  84 , cannula  20  rotates with obturator  80  to facilitate inserting cannula  20  into tissue  90 .  
         [0041]     Distal end  82  has a length of approximately 5 to 11.5 mm and is tapered at an angle of approximately 17.5 degrees to the center line. The threads on distal end  82  have a depth of approximately 0.5 to 1 mm, an angle of approximately 60 degrees and there are approximately 0.25 threads per mm. Intermediate portion  83  has a length of approximately 3 to 5 mm and a diameter D 2  of approximately 2.5 to 10 mm. Shaft portion  85  has a length of approximately 65 to 220 mm and a diameter of approximately 2.5 to 5.5 mm. Wings  89  are located on shaft portion  85  approximately 16.5 mm from a base  91  of handle  84 .  
         [0042]     In use, referring to  FIG. 1 , with cap  40  coupled to proximal end  22  of cannula  20  and obturator  80  located in cannula bore  30  with lateral wings  89  received in longitudinal slots  34 , the user inserts threaded distal tip  82  of obturator  80  into a small incision or portal  92  that has been made in tissue  90  to form a channel  95  in tissue  90 . The user then rotates handle  80  clockwise, inserting threaded distal portion  25  of cannula  20  into tissue  90 .  
         [0043]     Once distal portion  25  of cannula  20  is inserted into tissue  90 , the user removes obturator  80  from tissue  90  and cannula  20  by pulling handle  84  while holding cannula  20  in place in tissue  90 . Fluid can be aspirated or suction can be applied through cannula  20  by attaching a source of fluid or suction to port  36  of stopcock  26  and adjusting the opening of valve  38 . The user passes surgical instruments into tissue  90  by passing them through outer seal  60 , inner seal  70 , and bore  30  in cannula  20  to perform an arthroscopic, endoscopic, or laproscopic surgical procedure. Outer seal  60  and inner seal  70  form a seal around the surgical instrument when the surgical instrument is located within cannula  20 , and seal off cannula  20  when no surgical instrument is located therein.  
         [0044]     During the surgical procedure, the user can remove cap  40  from cannula  20 , e.g., to permit tissue that is too large to pass through cap  40  to be removed through cannula  90 . The user can reattach cap  40  to cannula  20  to again provide the sealing function of cap  40 . Cap  40  can be removed and reattached to cannula  20  as many times as desired during a surgical procedure. Once the user has completed the surgical procedure, the user removes cannula  20  from tissue  90  by rotating cannula counterclockwise.  
         [0045]     A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, the cannula can have a smooth outer surface rather than being threaded. The cannula also can have a valve other than a stopcock for aspirating fluid and applying suction. The distal threaded portion and the bore therethrough need not be tapered, e.g., when the cannula is manufactured by machining. The cannula can include more than two protrusion receiving formations. The protrusion receiving formations can be formed on an outer surface of the cannula.  
         [0046]     The cap can be releasably coupled to the proximal end of the cannula by a mechanism other than a J-lock, such as a quick release or a spring loaded ball with a detent. The cap can be aligned with the cannula by other than an enlarged knurl on locking ring, such as by printed material or engraved lines on the cap. The cap can include protrusion receiving formations for receiving corresponding protrusions on the obturator to facilitate turning the cap and cannula assembly by turning the obturator. The cap can be tethered to the cannula, such as by a flexible tie, to avoid losing cap when it is detached from the cannula. The cap can include a smaller or larger number of seals to limit leakage of fluid when a surgical instrument is inserted therethrough. The integral sealing member can be mechanically attached to the mating member, such as be forming pin holes through the mating member and the sealing member including rod shaped projections extending through the pin holes and each being capped with a head.  
         [0047]     The inner seal and outer seal can be attached to the cylindrical member by other than a snap-fit, such as by an adhesive. The inner seal can have an opening other than the slit therethrough, such as a circular or oblong aperture. The aperture through outer seal can have a shape other than circular, such as an elongated slot. The reinforcing rib on the outer seal can be on the inner side or the outer side of the outer seal, or both. The top wall of the outer seal also can include two or more reinforcing ribs surrounding the aperture. The top wall of the outer seal also can be of constant thickness.  
         [0048]     The obturator can be of constant diameter throughout. The obturator can include a smaller or larger number of lateral projections that correspond to an equal or greater number of longitudinal slots inside the cannula. Other types of interlocking mechanisms between the obturator and the cannula can be used. The distal end of the obturator can be smooth and the handle can be solid.  
         [0049]     In addition to the materials discussed above, the cannula, the cylindrical member, and the obturator can be made from any rigid biocompatible material such as a plastic, a metal, or a ceramic. Similarly, the integral seal, the inner seal, and the outer seal can be made of any elastomeric material such as latex or rubber.  
         [0050]     In use, the obturator can be inserted into the cannula with the cap removed when the cannula is being inserted into the tissue. The obturator can be reinserted into the cannula at the end of the surgical procedure to facilitate removing the cannula from the tissue. These and other embodiments are within the scope of the following claims.