Abstract:
A hernia repair patch ( 10 ) comprising a wire frame of a pair of overlapping v-shaped wire segments ( 12, 14 ) attached to a prosthetic fabric material ( 20 ). The vertices ( 18 ) of the v-shaped wire segments ( 12, 14 ) are disposed in opposite directions. The wire segments ( 12, 14 ) further include attached points ( 16 ) at free ends thereof. Said wire frame supporting the prosthetic fabric material may be formed of Nitinol or other suitable shape memory alloy.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to provisional application Ser. No. 60/758,445, filed Jan. 12, 2006 and which is hereby incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates generally to apparatus for use in hernia repair surgery, and more particularly to a prosthetic hernia repair patch that can be collapsed into a tube for laparoscopic delivery through a trocar and which deploys to a generally planar form when ejected from the trocar into the abdominal cavity. 
         [0004]    2. Discussion of the Prior Art 
         [0005]    Laparoscopic hernia repair procedures have been successfully used to treat inguinal, ventral, incisional and umbilical hernias for many years. Patients who utilized such laparoscopic procedures typically have recovered faster and undergone less pain than those who have undergone open surgery. 
         [0006]    In the past, when carrying out early laparoscopic hernia procedures, initially a prosthetic patch was made at the time of surgery from a sterile, woven, polypropylene mesh material. This material was folded in half to create a double layer and then cut to size, typically a 6 cm by 9 cm rectangle. Sutures were used to join the four corners of the rectangle and two additional sutures were positioned approximately midway along the unfolded edge. A slit was then created between these two additional sutures which was designed to accommodate the inferior epigastric vessels. Following dissection of the hernia sac away from the ipsilateral testicle and cord structures, the creation of a peritoneal incision and the subsequent dissection of the peritoneal flap and hernia sac away from the hernia defect and surrounding fascia and cord structures, the patch was rolled into a tube and inserted into a trocar sleeve that was then introduced through a larger diameter trocar, and delivered into the peritoneal cavity. A laparoscopic forceps was then used to unfurl the patch and place it anterior to the hernia defect and around the inferior epigastric vessels with the mesh covering both the direct and indirect hernia spaces. The mesh patch would then be held in place by stapling or suturing it to underlying fascia. Subsequently, the peritoneum was closed over the patch so that the entire piece of mesh was covered thereby. 
         [0007]    While the above procedure proved quite successful in terms of outcomes, the need to fabricate the mesh patch at the time of surgery, the later difficulty in unrolling and positioning the mesh patch material relative to the direct and indirect hernia spaces, and the need to then staple or suture the mesh patch in place necessarily added significantly to the time and expense required for carrying out the procedure. 
         [0008]    Hernia patches were thereafter developed for use in laparoscopic surgery that were prefabricated to conform to anatomical structures, as disclosed in U.S. Pat. No. 5,824,082 to Brown. These patches generally made use of an outer wire frame of an alloy having shape memory properties, and a prosthetic fabric material that attached about its periphery to this frame. The device could be readily deployed when released from a tubular laparoscopic introducer and remained in place without a need for stapling or suturing to underlying facie. This patch design, however, is somewhat difficult to manufacture as the mesh material utilized in its design required extensive stitching around its periphery to hold the wire or cable frame in place against the mesh. 
         [0009]    Therefore, a need exists for a hernia patch for use in laparoscopic surgery, which uses a simplified design that overcomes past difficulties of manufacture. The present invention fulfills that need. 
       SUMMARY OF THE INVENTION 
       [0010]    The hernia repair patch of the present invention comprises a wire frame of various designs including, but not limited to, a pair of overlapping “V” shaped wire segments with vertices disposed in opposite directions and further containing attached points at the free ends of the wire segments and a closed or slightly open circular loops near the vertices of both the “V” shaped wires. A synthetic prosthetic material, such as woven polypropylene or expanded PTFE (Gortex), is attached to the wire frame at only the few attached points although the material generally is supported by the entire wire frame. The wire frame supporting the mesh material may be formed of Nitinol or other suitable shape memory alloy. The frame can be attached to the prosthetic material so that the device has a generally rectangular shape of mesh with rounded corners when the alloy is in its austenite form and a compact shape of low profile when in a martensite form. 
         [0011]    The shape memory property of Nitinol may be either stress-induced or temperature-induced. When temperature-induced, the atomic percent of nickel in the alloy is such that the alloy exhibits a transformation temperature at about 37° C. (body temperature). Thus, when the patch is cooled, it can be readily formed into a compact configuration for placement in a delivery trocar. When ejected out of the trocar into the patients abdominal cavity, the patch warms to the point where the alloy is in its austenite form so that it springs into its functional, predetermined configuration. The central portion of the patch accommodates the inferior epigastric vessels and cord structures while the opposed end lobes cover the direct and indirect hernia space. Because the frame is integral to the patch, it does not migrate and, accordingly, need not be sutured or stapled in place. It remains anchored following its being covered by the peritoneum in a sandwich or laminated fashion. 
         [0012]    The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is an enlarged plan view of the hernia repair patch of the present invention; 
           [0014]      FIG. 2  is an enlarged plan view of the hernia repair patch in a collapsed configuration; and 
           [0015]      FIG. 3  is an enlarged view of one of the wires used to hold the frame member in place before attachment to the mesh material. 
           [0016]      FIG. 4  is an enlarged view of an alternative embodiment of one of the wires used to hold the frame member in place before attachment to the mesh material. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]    Referring first to  FIG. 1 , there is shown an enlarged view of the hernia repair patch of the present invention. The patch device is generally indicated by numeral  10  and includes an outer frame of wire members  12  and  14 . These wire members are preferably made up of a shape memory alloy of nickel and titanium commonly referred to as Nitinol. The shape memory properties of Nitinol can be especially useful in this device. For example, by proper adjustment of the relative concentration of nickel in the alloy, the wire frame can be made to exhibit a transition between austenitic form to martensitic form at about body temperature, thereby allowing for transformation to a convenient shape for either delivery or use. 
         [0018]    Alternatively, by proper adjustment of the relative concentration of nickel in the alloy, the wire frame can be made to exhibit a transition between austenitic form and martensitic form based upon stress-induced shape memory properties. In this case, a small amount of stress is placed on the Nitinol wire for deformation during delivery of the device before the wire regains its shape upon deployment and removal of that stress, irrespective of temperature. Although Nitinol wire (2-2.5 mm diameter) is preferred, wire members  12  and  14  may also be made of stainless steel, medical grade plastic, or other suitable material exhibiting a resilient property. The frame wires  12  and  14  are preferably radiopaque. While not utilizing the shape memory properties of Nitinol, these devices can be sufficiently collapsed and deployed if desired. 
         [0019]    Wire members  12  and  14  are separate, overlapping “V” shaped wire segments disposed in inverse orientations. The two ends of each wire are attach points  16 . At the attach points  16 , the wire may be bent in a circular, rounded fashion such that closed loops of approximately 540 degrees are formed. Near the vertices  18  of the wire frame members, they are bent in a rounded fashion so as to form either a closed loop of about 540 degrees or a slightly open loop where the two sides of the wire converge. Both wire frame members  12  and  14  have sides of unequal length where one side is typically 5-10 mm shorter than the other. This design allows for a slimmer profile when the device is collapsed for delivery, as will be discussed later. Generally, the manufactured shape of the wire is originally formed with a wide angle of 90-120 degrees between the two sides of the wire. (See  FIG. 3 ) This dimension is narrowed to about 30 degrees when the wire is being attached to the mesh member so as to provide more spring expansion with a slimmer wire. 
         [0020]    Alternatively, wire member  12  may be configured as in  FIG. 4 . Here, the wire member  12  includes a unshaped and apex  34 . Whereas in the preferred embodiment shown in  FIGS. 1-3  the vertices  18  of the wires is a coiled loop, in this alternative embodiment the apex  34  is u-shaped and uses a suture loop to secure it to the mesh while allowing some slippage. Furthermore, the attachment points  36  are circular or slightly oval-shaped loops as opposed to the circular coils used in the preferred embodiment. The attachment points  36  use a suture loop to secure the mesh to the wire member. In the alternative embodiment, as in the preferred embodiment, the wire member has sides of unequal lengths. 
         [0021]    Supported on the wire members  12  and  14  is a prosthetic fabric  20 , preferably woven of polypropylene plastic of expanded PTFE (Gortex). The overall shape of the fabric is rectangular with rounded corners. There may also be slight indentations along the upper and lower borders of this mesh, although this is optional. Various sizes of mesh could be used with wire lengths adjusted accordingly. This material allows the device to be steam sterilized. When placed in a patient&#39;s body, the two sides of fabric mesh  20 , referred to as lobes  22  and  24 , are adapted to be positioned over the direct and the indirect hernia spaces, respectively. When this is done, the central portion at the intersection of the wire members  12  and  14 , indicated generally by numeral  26 , will allow placement without interference with the inferior epigastric vessels. 
         [0022]    The manner in which the fabric is held to the wires differs significantly from prior art devices. First, at each of the four attach points  16  of the wires, elastic suture material  28  is used to hold the fabric mesh  20  to the wires  12  and  14 . Using elastic sutures helps to accommodate elongation as the wire frame members are squeezed closed to pass through a cannula during insertion of the device into a body. The curvatures  18  at the vertices of the wires use a suture loop  30  to secure mesh while allowing slippage. Allowing this slippage and expansion of the vertices  18  of the wire member is necessary as these midpoints tend to expand outward when squeezed together. When the device is constructed in this way, there is a substantial savings of time and effort to manufacture the prosthetic as only six fastening points are required at the ends and midpoints, rather than the hundred or so used to secure mesh to its frame in some prior art devices. The simple design and easy to manufacture construction make for an extremely useful device. 
         [0023]    Additionally, or alternatively, slipping the loops at the ends and midpoints of the members  12  and  14  over one or two strands of mesh can facilitate attachment to the mesh. This operates in a similar fashion to slipping a key in to a key ring. Attaching mesh this way eliminates the need for using any type of fastening sutures and reduces manufacturing and assembly costs. Also, loops  32  of polypropylene or similar thread-like material are preferably placed around wires  12  and  14  at their two cross over points and through the mesh for wire stabilization. These would be loose enough to allow the wire to slide through it when compressed for delivery. 
         [0024]    For additional comfort and protection of a patient, the mesh material  20  is folded over the somewhat pointed ends of the frame members and secured to make the ends of the wire  16  less traumatic. 
         [0025]    Assuming members  12  and  14  are Nitinol and that they are cooled below the transformation state so that they are in their martensitic form, the prosthesis  10  can be collapsed in an accordion-type manner to form a generally cylindrical structure as illustrated in  FIG. 2 . Note the way that a slim profile results, facilitating delivery due to the rounded ends of the frame wires  12  and  14  being located at various locations as best seen in  FIG. 2 . 
         [0026]    Typically, the outside diameter of the attach points and vertices  16  and  18  would be around 3 mm to facilitate fitting though a 5 mm cannula when the mesh is attached. This collapsed shape allows the prosthesis to be introduced into the abdominal cavity through a tubular trocar. As the shape memory alloy members  12  and  14  warm up to body temperature, they transform to their austenitic form as shown in  FIG. 1 . Using a laparoscopic forceps, the prosthesis  10  of  FIG. 1  can be grasped and repositioned by the surgeon until the lobes  22  and  24  and the narrowed center section  26  are appropriately located for covering the hernia defect. Observing this placement of the device is possible as the device is visible when viewed on an x-ray machine. 
         [0027]    Those skilled in the art will appreciate that the prosthesis may be manufactured in a variety of shapes and sizes to accommodate children, adults, males and females and especially the type of hernia encountered. It can be contained in a sterile pack until ready for use. While Nitinol is the preferred shape memory alloy, other alloys, such as gold-cadmium, nickel-aluminum and manganese-copper would also be suitable. Moreover, the prosthetic fabric material  20  need not be polypropylene mesh, but can also comprise other suitable materials, such as body-compatible biaxially oriented polymeric films. 
         [0028]    Without limitation, the major axis of the prosthesis  10  is typically in a range of about 8-16 cms long and the minor axis typically is about 5-12 cms wide. Such device can be tightly fitted into a cylinder, as shown in  FIG. 2 , so as to fit within the internal lumen of a trocar or introducer sheath. 
         [0029]    The invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.