Abstract:
A model for practicing transabdominal pre-peritoneal (TAPP) and total extraperitoneal (TEP) approaches for laparoscopic hernia repairs is provided. The model simulates an insufflated space between the abdominal muscles and peritoneum. A spring layer may be incorporated to provide a realistic resiliency to the model while in the simulated insufflated configuration. At least one hole is provided in the model from which synthetic tissue protrudes to simulate a hernia. The model is used to selectively simulate direct, indirect and femoral inguinal hernias as well as incisional hernias by removably placing the protruding simulated tissue into any one of several openings. The model contains all important anatomical structures and sits on a base frame or is connected to a rigid simulated pelvis. When located inside a laparoscopic trainer with an angled top cover, the model provides an ideal simulation for teaching and practicing laparoscopic hernia repair.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and benefit of U.S. Provisional Patent Application Ser. No. 61/823,834 entitled “Hernia model” filed on May 15, 2013 and U.S. Provisional Patent Application Ser. No. 61/973,999 entitled “Hernia model” filed on Apr. 2, 2014, all of which are incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     This application relates to surgical training tools, and in particular, to simulated tissue structures and models for teaching and practicing the repair of a hernia. 
     BACKGROUND OF THE INVENTION 
     A hernia is the protrusion of an organ or the fascia of an organ through the abdominal wall. This occurs when the abdominal walls weaken either from incorrect formation at birth, recent surgery or trauma. The most common types of hernias are inguinal and incisional. Inguinal hernias occur in the groin area in both males and females but they are most common in men to the right and left of the midline where the spermatic cords and arteries pass through the spaces in the abdominal wall. There are three possible spaces in the abdominal wall for the hernia to pass through: direct, indirect and femoral. The direct space is medial to the epigastric vessels while the indirect space is lateral to the epigastric vessels. A femoral hernia occurs when the organs protrude through a large femoral ring into the femoral canal. Incisional hernias occur after a surgery when the abdominal wall does not heal correctly, causing the internal organs and fascia to push through. 
     Hernias can be repaired by either open or laparoscopic surgery. In laparoscopic surgery, a trocar is inserted to access a body cavity and to create a channel for the insertion of a camera, such as a laparoscope. The camera provides a live video feed capturing images that are then displayed to the surgeon on one or more monitors. Another trocar is inserted to create a pathway through which surgical instruments can be passed for performing procedures observed on the monitor. The targeted tissue location such as the abdomen is typically enlarged by delivering carbon dioxide gas to insufflate the body cavity and create a working space large enough to accommodate the scope and instruments used by the surgeon. The insufflation pressure in the tissue cavity is maintained by using specialized trocars. Laparoscopic repair has many advantages over the traditional open surgery repair including quicker recovery and less pain. Therefore, it is often more desirable for the patient to undergo a laparoscopic repair. However, laparoscopic repair requires an experienced surgeon. In order for surgeons to practice laparoscopic hernia repairs, a realistic, anatomically correct model for use in a laparoscopic training device is needed. 
     Generally, there are two ways to repair an inguinal hernia laparoscopically. The first and more often taught way is called transabdominal pre-peritoneal (TAPP). The TAPP approach involves placing the laparoscopic instruments all the way into the insufflated abdominal cavity and approaching the hernia from below by cutting a hole in the peritoneum. The hernia is then resected, mesh is placed over the weakened abdominal wall and the peritoneum is closed. The second way of reducing an inguinal hernia is called total extraperitoneal (TEP). The TEP approach is more difficult since it involves entering the space between the peritoneum and the abdominal wall without puncturing the peritoneum. Once the trocar has been inserted into that space, a balloon is used to open up the space to allow for easier movement of the instruments and less blunt dissection. When the balloon is removed, the space is insufflated and the hernia is found in that same plane. When the hernia is found, it is resected back into the abdominal cavity, the peritoneum laid flat and mesh placed over the weakened abdominal wall. When surgeons are learning how to perform laparoscopic surgery, they are taught TAPP first since like most other laparoscopic procedures, it is performed inside the abdominal cavity. TEP is considered more advanced and surgeons need a way to safely learn and practice the procedure. Due to the need for a safe practice model for both beginner surgeons learning TAPP as well as more advanced surgeons learning TEP, a hernia model that allows for both procedures to be practiced is needed. 
     In order to help patient outcomes and recoveries, surgeons need a way to practice laparoscopic hernia repairs outside of the operating room. The practice model needs to be anatomically correct and include all important landmarks normally seen during surgery in order to give the surgeon or resident the most realistic practice possible. Additionally, the model should allow the surgeon to practice incisional and inguinal (TAPP and TEP) procedures. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, an anatomical model for surgical training is provided. The model includes a simulated abdominal wall located at a first end of the model. The simulated abdominal wall has an inner surface and an outer surface. The simulated abdominal wall includes at least one opening extending between the inner surface and the outer surface defining a hernia opening. The model includes a simulated peritoneum located at a second end of the model. The simulated peritoneum has an inner surface and an outer surface. The simulated peritoneum is connected and adjacent to the simulated abdominal wall such that the simulated abdominal wall and the simulated peritoneum are substantially coplanar when in an open configuration and the inner surface of the simulated abdominal wall and the inner surface of the peritoneum together define a common inner surface and an overall flexible model. The model further includes a first layer of synthetic tissue. The first layer of synthetic tissue has a bottom surface and a top surface. The first layer of synthetic tissue overlays at least a portion of the simulated abdominal wall. At least part of the first layer is selectively adhered to the simulated abdominal wall and, in another variation, at least part of the first layer is adhered to the simulated abdominal wall and to the simulated peritoneum. The model further includes a plurality of simulated tissue components positioned between the first layer and the simulated abdominal wall. At least some of the simulated tissue components are adhered, at least in part, to at least one of the first layer, the simulated peritoneum, and the simulated abdominal wall. The model has a curved configuration. When in the curved configuration, part of the simulated abdominal wall is located above the simulated peritoneum and a cavity is defined between the simulated abdominal wall and the simulated peritoneum with the first end and the second end defining, in part, an opening into the cavity. In one variation, the model includes a spring layer that extends through the simulated abdominal wall and the simulated peritoneum. 
     According to another aspect of the invention, an anatomical model for surgical training is provided. The model includes a simulated abdominal wall located at a first end of the model. The simulated abdominal wall has an inner surface and an outer surface. The simulated abdominal wall has at least one opening extending between the inner surface and the outer surface. The model includes at least a portion of a simulated pelvis that is located at a second end of the model. The simulated pelvis has an inner surface and an outer surface. The simulated pelvis is connected and adjacent to the simulated abdominal wall such that the inner surface of the simulated abdominal wall and the inner surface of the simulated pelvis define a common inner surface of the model. The model further includes a first layer of synthetic tissue having a bottom surface and a top surface. The first layer of synthetic tissue overlays at least a portion of the simulated pelvis and at least a portion of the simulated abdominal wall. The first layer of synthetic tissue is adhered to at least a portion of the simulated pelvis and to at least a portion of the simulated abdominal wall. The first layer includes at least one opening aligned with the at least one opening in the simulated abdominal wall. The model includes a second layer of synthetic tissue having a bottom surface and a top surface. The second layer of synthetic tissue overlays at least a portion of the top surface of the first layer. The second layer includes at least one opening aligned with the at least one opening in the simulated abdominal wall. The model further includes a plurality of simulated tissue components positioned between the first layer of synthetic tissue and the second layer of synthetic tissue. At least some of the plurality of simulated tissue components is adhered, at least in part, to at least one of the first layer of synthetic tissue and the second layer of synthetic tissue. The model further includes a synthetic peritoneum overlaying at least one of the simulated abdominal wall and the simulated pelvis and is located above the second layer of synthetic tissue. At least a portion of the synthetic peritoneum is removably pushed into one of the openings in the simulated abdominal wall to simulate a hernia. 
     According to another aspect of the invention, a surgical simulation system for practicing hernia repair is provided. The surgical simulation system includes a hernia model placed inside a surgical training device. The hernia model includes a simulated abdominal wall located at a first end of the model. The simulated abdominal wall has an inner surface and an outer surface. The simulated abdominal wall has at least one opening extending between the inner surface and the outer surface. The hernia model includes at least a portion of a simulated pelvis located at a second end of the hernia model. The simulated pelvis has an inner surface and an outer surface. The simulated pelvis is connected to the simulated abdominal wall such that the inner surface of the simulated abdominal wall and the inner surface of the simulated pelvis define a common inner surface of the model. The hernia model includes a first layer of synthetic tissue having a bottom surface and a top surface. The first layer of synthetic tissue overlays at least a portion of the simulated pelvis and at least a portion of the simulated abdominal wall. The first layer is adhered to at least a portion of the simulated pelvis and to at least a portion of the simulated abdominal wall. The first layer includes at least one opening aligned with the at least one opening in the simulated abdominal wall. The model further includes a second layer of synthetic tissue having a bottom surface and a top surface. The second layer overlays at least a portion of the top surface of the first layer. The second layer includes at least one opening aligned with the at least one opening in the simulated abdominal wall and the at least one opening in the first layer. The hernia model also includes a plurality of simulated tissue components positioned between the first layer of synthetic tissue and the second layer of synthetic tissue. At least some of the plurality of simulated tissue components are adhered, at least in part, to at least one of the first layer of synthetic tissue and the second layer of synthetic tissue. The model further includes a synthetic peritoneum overlaying at least a portion of the simulated abdominal wall and at least a portion of the simulated pelvis. The synthetic peritoneum is positioned above the second layer of synthetic tissue. The surgical training device includes a base and a top cover connected to and spaced apart from the base to define an internal cavity. The internal cavity is at least partially obstructed from direct observation by a user and is configured for practicing laparoscopic surgical techniques. The top cover includes an aperture or penetrable simulated tissue region for the passage of surgical instruments into the internal cavity. The hernia model is positioned inside the internal cavity. 
     According to another aspect of the invention, a model that allows surgeons and residents to practice incisional and inguinal hernia repairs is provided. The model is a clam-shaped and simulates the insufflated space between the abdominal muscles and peritoneum. A hole is provided in the model from which a simulated peritoneum and/or simulated bowel protrudes to create a simulated hernia. The model contains all important anatomical structures including Cooper&#39;s ligament, the iliopubic tract, the pubic ramus bone, the medial umbilical ligament, the triangle of doom, triangle of pain and the spermatic cords. The model is covered with a layer of simulated tissue to allow users to practice dissecting in order to find and navigate the important anatomical landmarks and to safely repair the hernia. Additionally, the model is designed with a thick abdominal wall to allow the surgeon to practice tacking mesh to repair the hernia. Silicone is used to create the thick abdominal walls, simulated anatomical structures and synthetic tissue. A spring layer may be incorporated to provide realistic resiliency to the model while maintaining a simulated insufflated space configuration or curved configuration. The model may be used to selectively simulate direct, indirect and femoral inguinal hernia repairs as well as incisional hernia repairs by removably placing the protruding simulated tissue into any one of three openings in the model. The model sits on a base or frame that imparts and maintains the clam shape or is connected to a rigid simulated pelvis. When located inside a laparoscopic trainer with an angled top cover to simulate a Trendelenburg position of the patient, the model provides an ideal simulation for teaching and practicing laparoscopic hernia repair. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side perspective view of a hernia model according to the present invention. 
         FIG. 2  is a front perspective view of a hernia model according to the present invention. 
         FIG. 3  is rear perspective view of a hernia model according to the present invention. 
         FIG. 4  is a top view of an anatomical portion of a hernia model according to the present invention. 
         FIG. 5  is a top view of an anatomical portion of a hernia model according to the present invention. 
         FIG. 6  is a top view of an anatomical portion of a hernia model with human hands shown retracting simulated tissue according to the present invention. 
         FIG. 7  is a bottom perspective view of an anatomical portion of a hernia model according to the present invention. 
         FIG. 8  is bottom view of an anatomical portion of a hernia model according to the present invention. 
         FIG. 9  is a top perspective view of a frame of a hernia model according to the present invention. 
         FIG. 10  is a side perspective view of a laparoscopic trainer. 
         FIG. 11  is a side perspective view of a laparoscopic trainer with an angled top cover. 
         FIG. 12  is a side perspective view of a laparoscopic trainer with a hernia model according to the present invention. 
         FIG. 13  is a rear perspective view of a laparoscopic trainer with a hernia model according to the present invention. 
         FIG. 14  is a front perspective view of a laparoscopic trainer with a hernia model according to the present invention. 
         FIG. 15  is a front perspective view of a hernia model with human hands shown retracting simulated tissue according to the present invention. 
         FIG. 16  is a front perspective view of a hernia model with human hands shown retracting simulated tissue according to the present invention. 
         FIG. 17  is a front top perspective view of a hernia model according to the present invention. 
         FIG. 18  is a rear top perspective view of a hernia model according to the present invention. 
         FIG. 19  is a top view of a hernia model according to the present invention. 
         FIG. 20  is a top view of a hernia model according to the present invention. 
         FIG. 21  is a rear top perspective view of a hernia model according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-3 , there is shown a side, front and rear view, respectively, of a hernia model  10  according to the present invention. The hernia model  10  includes an anatomical portion  12  supported by a frame  14 . As seen most clearly in  FIG. 1 , the substantially planar anatomical portion  12  is maintained in a curved configuration such that the major part of the anatomical portion  12  is substantially C-shaped forming a half or open generally cylindrical configuration. The concavity formed inside the C-shaped disposition of the anatomical portion  12  advantageously simulates an insufflated space between an artificial muscular abdominal wall generally located at the top of the C shape and the simulated peritoneum  18  generally located at the bottom of the C shape. The simulated muscular abdominal wall forms approximately the top half or more than the top half of the C-shaped curve; whereas, the bottom half or less than the bottom half of the C-shaped curve is formed by the simulated peritoneum  18 . The open clamshell-like configuration advantageously provides a realistic surgical approach to repairing a hernia when viewed by the user from the front of the hernia model  10  as in  FIG. 2 . 
     The frame or stand  14  divides the hernia model  10  into an upper portion and a lower portion. The lower portion constitutes approximately one-third of the entire height of the hernia model  10  and simulates the abdominal cavity beneath the peritoneum. The lower portion contains that part of the anatomical portion  12  such as the simulated bowel that protrudes through the simulated peritoneum  18  and through the simulated muscular abdominal wall. The upper portion contains the anatomical portion  12 .  FIGS. 1-3  illustrate a simulated bowel residing in the lower portion and extending upwardly through an opening in the peritoneum  18  into the concavity of the upper portion. The simulated bowel crosses the concavity of the insufflated space and exits through an opening in the muscular abdominal wall to simulate a hernia. One or more exit openings in the simulated muscular abdominal wall of the anatomical portion  12  is provided to simulate the possible spaces in the abdominal wall for the hernia to pass through. Generally, there are three spaces through which a hernia may pass. These spaces are the direct space, the indirect space and the femoral space. If all three openings are provided in the hernia model, the distal end of simulated bowel is inserted into any one of the exit openings for practicing hernia repair through any of the three spaces. The surgeon practices approaching the simulated insufflated space of the hernia model  10  from the front, either from below the peritoneum or above the peritoneum for practicing TAPP or TEP, respectively. The surgeon visualizes the insufflated space, practices carefully dissecting simulated fascia layers, identifying a variety of visual anatomical markers, navigating around them to approach the bowel, resecting the hernia and placing mesh to patch and close any spaces. 
     The anatomical portion  12  of the hernia model  10  will now be described in detail with reference to  FIGS. 4-8 . Turning to  FIG. 4 , there is shown a top view of an anatomical portion  12  of the hernia model  10 . The anatomical portion  12  is a substantially planar object having varying thickness and materials. The anatomical portion  12  includes a simulated muscular abdominal wall portion  16  interconnected in substantially the same plane to a simulated peritoneum portion  18 . Aside from the relatively thicker abdominal wall portion  16  relative to the peritoneum portion  18 , both the abdominal wall portion  16  and peritoneum portion  18  are substantially coplanar. In human anatomy, the layers of the abdominal wall are from superficial to deep: 1) skin, 2) fascia, 3) muscle, which includes the rectus abdominis, external oblique muscle, internal oblique muscle and transverse abdominal muscle, 4) fascia transversalis, and 5) peritoneum. These abdominal layers are sandwiched or layered above each other to form part of the abdominal wall portion  16 . In the present invention, one or more layers representing muscle are positioned substantially coplanar with or otherwise adjacent to the simulated peritoneum portion. In this arrangement, the top side (anterior facing surface) of the simulated peritoneum  18  is substantially coplanar or adjacent to the bottom side (posterior facing surface) of the simulated muscular abdominal wall portion  16  such that when the substantially planar anatomical portion  12  is curved into a C-shape configuration the bottom side of the simulated muscular abdominal wall portion  16  faces and is spaced apart from the top side of the simulated peritoneum  18 . The interior portion of the C-shaped structure simulates an insufflated space. In real surgery, the insufflated space is created by inserting a trocar between the muscle layer and peritoneum and delivering fluid such as carbon dioxide gas under pressure from the proximal end of the trocar to the distal end of the trocar to spread apart the muscle layer from the peritoneum to create a working space. The simulated insufflation cavity of the present invention is the concavity of the C-shaped orientation which is approximately 5 inches in height and approximately 10 inches in length. As can be seen in  FIG. 4 , the simulated muscular abdominal wall portion  16  is approximately 8 inches long and approximately 7.5 inches wide and is adjacent to the simulated peritoneum  18  which is approximately 3 inches long and approximately 7.5 inches wide. When formed into a clamshell configuration, the simulated muscular abdominal wall portion  16  is disposed at the top of the hernia model  10  and follows the C-shaped curve down beyond the halfway mark of the C-shape. The simulated peritoneum  18  is disposed at the bottom of the C-shape and curves upwardly approximately a third of the way along the C-shape when the anatomical portion  12  is formed into a clamshell. Overall, the substantially planar anatomical portion  12  is approximately 7.4 inches wide and approximately 11 inches long. The anatomical portion  12  further includes a simulated fascia layer  20  located on the inner surface of the anatomical portion  12 . The simulated fascia layer  20  is a thin layer that is partially translucent and draped over the simulated muscular abdominal wall  16 . The simulated fascia layer  20  is glued with adhesive in one or more locations and generally does not extend to completely over the simulated peritoneum  18  when laid flat as shown in  FIG. 4 . The simulated peritoneum  18  includes an opening  22  simulating the location of a ruptured peritoneum through which a simulated bowel  24  protrudes above the inner or top surface of the peritoneum  18 . The simulated bowel  24  is part of the anatomical portion  12  although it is loosely connected thereto such that the simulated bowel  24  may be moved, pulled and pushed through the opening  22  and other spaces. 
     Turning to  FIG. 5 , there is shown a top view of the anatomical portion  12  with the simulated fascia layer  20  uncovering the underlying simulated muscular abdominal wall  16 . Various anatomical structures are provided on the surface of the simulated muscular abdominal wall  16 . These landmarks include but are not limited to Cooper&#39;s ligament  72 , vas deferens  88 , external iliac vessels  74 ,  76 , spermatic vessels  78 ,  80 , nerves  90 , and iliopubic tract  86  arranged as labeled in  FIG. 5 . A piece of hard plastic (not shown) may also be embedded to simulate a femoral bone. In addition to opening  22  in the simulated peritoneum  18 , one or more additional openings are formed through the simulated muscular abdominal wall  16 . These additional openings define exit openings or spaces through which the bowel protrudes in a hernia. In  FIG. 5 , a first opening  26  and a second opening  28  are formed through the simulated muscular abdominal wall  16  to simulate the direct space and indirect space, respectively.  FIG. 6  illustrates the first and second openings  26 ,  28  more clearly. Also visible in both  FIGS. 5 and 6  is the curved intersection between the simulated muscular abdominal wall  16  and the simulated peritoneum  18 . The simulated bowel  24  is passed through the opening  22  in the simulated peritoneum  18  such that the distal end resides above the inner surface and at least a portion of the simulated bowel  24  is above the top surface of the peritoneum  18 . The distal end of the simulated bowel  24  is then passed into either of the first opening  26  or second opening  28  to simulate a hernia located in the direct or indirect space, respectively. In  FIG. 4 , the simulated bowel  24  is shown passed into the second opening  28  representing the indirect space. The hernia model  10  simulates a portion of the anatomy lateral to the midline  45  of a patient. 
     Turning now to  FIGS. 7 and 8 , there is shown a perspective and bottom view of the outer surface of the anatomical portion  12 . The anatomical portion  12  is built upon a layer of flexible wire mesh  30  such as chicken wire. The wire mesh material  30  is made of thin, flexible galvanized steel wire crisscrossing to form small square or other-shaped windows. The outer surface of the wire mesh layer  30  is covered with a first layer of silicone  32  which is glued to the wire mesh layer  30 . The inner surface of the wire mesh layer  30  is covered with a second layer of silicone  34  sandwiching the wire mesh layer  30  between the first and second layers of silicone  32 ,  34  forming the simulated muscular abdominal wall  16  at one end of the anatomical portion  12 . At the other end of the anatomical portion  12 , the inner surface of the wire mesh  30  is covered with a yellow foam layer  36  forming the simulated peritoneum  18 . The yellow foam layer  36  that is approximately 1/16 of an inch thick is adhered to inner surface of the mesh layer with adhesive with the outer edges of the yellow foam layer  36  being wrapped over the outer edges of the mesh layer  30 . The yellow foam layer  36  forms the finished inner surface of one end of the anatomical portion  12 . The simulated muscular abdominal wall  16  comprising the first and second silicone layers  32 ,  34  and wire mesh layer  30  is approximately 0.75 inches thick. The same wire mesh layer or frame  30  extends throughout the anatomical portion  12  defining the general plane of the anatomical portion  12 . The simulated peritoneum  18  is substantially thinner than the simulated muscular abdominal wall  16  although still generally coplanar and adjacent to the simulated abdominal wall  16 . The thick simulated muscular abdominal wall  16  permits the surgeon to tack surgical mesh to the abdominal wall to practice patching the hernia. 
     With reference back to  FIGS. 5-6 , the inner surface of the second silicone layer  34  is populated with a variety of anatomical landmarks as mentioned above. The second silicone layer  34  is textured and additional silicone layers may be employed above the second layer  34  to complete the anatomical geography. The tubular simulated vessels and nerves are made of silicone and have diameters of approximately 0.185 inches. The simulated Cooper&#39;s ligament  72 , iliopubic tract  86  and vas deferens  88  are also made of silicone and have diameters of approximately 0.25 inches. The thick external iliac vessels  74 ,  76  are made of silicone and have a diameter of approximately 0.25-0.375 inches. These tubular structures are made by pouring uncured silicone into straw like tubes and removed them after they solidify. The simulated bowel  24  is made from a thin layer of pink-colored silicone. The silicone comprising the iliopubic tract  86 , Cooper&#39;s ligament  72  and vas deferens  88  is colored white, the nerves are colored yellow, the external iliac vein  74  and spermatic vein  78  are blue, the external iliac artery  76  and the spermatic artery  80  are red and the remaining vessels are red or pink. 
     Turning now to  FIG. 9 , there is shown a perspective view of a frame  14  configured to hold the anatomical portion  12  of the hernia model  10  according to the present invention. The frame  14  includes a rectangular lower frame portion  38  and an upper frame receiving portion  40 . The lower frame portion  38  is configured to house excess simulated bowel  24  that is simulated to reside below the peritoneum. The lower frame portion  38  includes a base and two or more upwardly extending side walls to form a rectangular container with a top wall. At least one opening is provided, for example via an open side, into the lower frame portion  38 . The upper frame portion  40  is configured to receive the anatomical portion  12  and retain the anatomical portion  12  in a clamshell or C-shaped orientation. As such, the upper frame portion  40  includes a C-shaped receiving portion to receive and retain the anatomical portion in a C-shaped configuration. In  FIG. 9 , the C-shaped receiving portion is formed by two upwardly extending C-shaped claws or prongs  42 ,  44  that are attached to a top wall of the lower frame portion  38 . Any number of C-shaped prongs  42 ,  44  including a wide singular prong may be employed to retain the anatomical portion  12 . The lower frame portion  14  is approximately 10.5 inches wide, approximately 4 inches deep and 3.5 inches tall. The C-shaped prongs  42 ,  44  are approximately 6 inches in height and each have a concavity that is approximately 4 inches deep. 
     As described above, the anatomical portion  12  is substantially planar and made of flexible silicone, flexible foam and flexible wire mesh. The wire mesh layer  30  advantageously imparts the anatomical portion  12  with a resiliency that permits the planar anatomical portion  12  to be bent into a substantially semi-cylindrical or C-shaped configuration and placed into the C-shaped receiving prong(s) of the frame  14 . The mesh layer  30  acts as a spring layer such that when the anatomical portion  12  is bent and inserted into the frame  14 , it exhibits a biasing force against the frame  14  advantageously keeping the anatomical portion  12  in position. Removability of the anatomical portion  12  allows for interchangeability of the anatomical portion  12  after it has been used several times for replacement, repair, reconstruction and compact transport. When the anatomical portion  12  is removed from the frame  14 , the resilient mesh layer  30  aids in springing the anatomical portion  12  back to its substantially planar orientation. Hence, the mesh spring layer advantageously keeps the silicone and foam layers  32 ,  34  and  36  from collapsing onto itself while in the clam shape. 
     Although the hernia model  10  is described above to be comprised of an anatomical portion  12  that is separate from the frame  14 , one skilled in the art will recognize that, in an alternative variation, the hernia model  10  can be constructed such that the frame  14  and anatomical portion  12  is formed integrally as one piece. Furthermore, although the hernia model  10  of the present invention may be used to practice hernia repair in a simulated open surgical procedure, the hernia model  10  is also advantageously configured for practicing laparoscopic hernia repair, in particular, employing the TEP approach. As such, the hernia model  10  of the present invention is configured to function together with a specialized laparoscopic trainer which will now be discussed in detail. 
     Turning now to  FIG. 10 , there is shown a laparoscopic trainer  46 . The laparoscopic trainer  46  is described in co-pending U.S. patent application Ser. No. 13/248,449 entitled “Portable laparoscopic trainer” and filed on Sep. 29, 2011 by Pravong et al. to Applied Medical Resources Corporation and published as U.S. Patent Publication No. 2012/0082970, hereby incorporated by reference in its entirety herein. The laparoscopic trainer  46  includes a top cover  48  connected to a base  50  by a pair of legs  52  spacing the top cover  48  from the base  50 . The laparoscopic trainer  46  is configured to mimic the torso of a patient such as the abdominal region. The top cover  48  is representative of the anterior surface of the patient and the space between the top cover  48  and the base  50  is representative of an interior of the patient or body cavity where organs reside. The laparoscopic trainer  46  is a useful tool for teaching, practicing and demonstrating various surgical procedures and their related instruments in simulation of a patient. Surgical instruments are inserted into the cavity through pre-established apertures  58 ,  60  in the top cover  48 . These pre-established apertures may include seals that simulate trocars or may include simulated tissue  60  that simulates the patient&#39;s skin and abdominal wall portions. Various tools and techniques may be used to penetrate the top cover  48  to perform mock procedures on model organs placed between the top cover  48  and the base  50  such as the hernia model  10 . When placed inside the cavity of the trainer  46 , the hernia model  10  is generally obscured from the perspective of the user who can then practice performing surgical techniques laparoscopically by viewing the surgical site indirectly via a video feed displayed on a video monitor. 
     A video display monitor  54  that is hinged to the top cover  48  is shown in a closed orientation in  FIG. 10  and in an open orientation in  FIGS. 11-14 . The video monitor  54  is connectable to a variety of visual systems for delivering an image to the monitor  54 . For example, a laparoscope inserted through one of the pre-established apertures  58 ,  60  or a webcam located in the cavity and used to observe the simulated procedure can be connected to the video monitor  54  and/or a mobile computing device to provide an image to the user. In another variation, the top cover  48  does not include a video display but includes means for supporting a laptop computer, a mobile digital device or tablet such as an IPAD® and connecting it by wire or wirelessly to the trainer  46 . 
     When assembled, the top cover  48  is positioned directly above the base  50  with the legs  52  located substantially at the periphery and interconnected between the top cover  48  and base  50 . The top cover  48  and base  50  are substantially the same shape and size and have substantially the same peripheral outline. Although the trainer  46  has no sidewalls, the legs  52  partially obscure the internal cavity from view from an otherwise open-sided trainer  46 . The top cover  48  includes a first insert  56  removable and replaceable with respect to the top cover  48 , in particular, insertable into and removable from an opening formed in the top cover  48 . The first insert  56  includes a plurality of apertures  58  to serve as fixed insertion ports for a variety of instruments. The apertures  58  may include various seals. The first insert  56  also includes a tissue simulation region  60  for simulating the skin or several layers of tissue. In one embodiment, the tissue simulation region  60  is configured as a second insert provided within the first insert  56 . The second insert is removable and replaceable via snap-fit, friction fit or threaded engagement or other means with respect to the top cover  48  or with respect to the first insert  56  if provided. 
     Turning now to  FIG. 11 , the laparoscopic trainer  46  includes a top cover  48  that angulates with respect to the base  50 . The legs  52  are configured to permit the angle of the top cover  48  with respect to the base  50  to be adjusted.  FIG. 11  illustrates the trainer  46  adjusted to an angulation of approximately 30-45 degrees with respect to the base  50  and in another variation approximately 30-35 degrees. The angulation of the trainer  46  advantageously simulates a patient in a Trendelenburg or reverse Trendelenburg position. In the Trendelenburg position the body is tilted such that it is laid flat on the back with the feet higher than the head or vice versa. The Trendelenburg position allows better access to the pelvic organs as gravity pulls the intestines away from the pelvis to thereby prevent encroachment of the intestines upon the pelvic operating field to provide more working space inside the abdominal cavity in which the surgeon can more easily manipulate organs. The selected angulation of the top cover  48  is locked by tightening thumbscrews provided on the legs  52 . The angulation of the top cover  48  of the trainer  46  with respect to the base  50  is particularly advantageous with respect to accommodating the hernia model  10  of the present invention. 
     With the top cover  48  angled as shown in  FIG. 11 , the hernia model  10  is inserted into the cavity of the trainer  46  and positioned between the top cover  48  and base  50  as shown in  FIG. 12 . The rear view of the trainer  46  with the hernia model  10  inserted is shown in  FIG. 13 . As described above, the anatomical portion  12  of the hernia model  10  is held in a C-shaped configuration in frame  14  such that the opening to the C-shape or opening to the clamshell is oriented approximately 90 degrees from the vertical. In other words, if the anatomical portion  12  is considered to be substantially U-shaped with the opening to the U facing upwardly, when the U is turned 90 degrees on its side, a substantially C-shaped configuration is created. With the hernia model  10  inserted into the trainer  46 , the opening of the C shape faces the front of the trainer  46  or, in other words, the opening or concavity of the C shape faces the top cover  48 . If the top cover  48  was not angled, the concavity of the C shape would not face the top cover  48  and, instead, the opening of the C shape would face the front side between the top cover  48  and the base  50 . The top cover  48  is angled such that the top cover  48  is positioned between the user and the hernia model  10  obscuring the opening of the C shape from the user. The direction of approach by the user is depicted in  FIG. 12  by the arrow  62 . It is substantially along this direction  62  that instruments will be inserted through the tissue simulation region  60  and apertures  58  in the top cover  48  to access the hernia model  10 . In one variation, the simulated fascia layer  20  is connected to the trainer  46  with clips (not shown) that are connected to the trainer  46 . The clips may be retractable and attached to the top cover  48 , base  50 , or legs  52 . When clipped with the clips, the simulated fascia layer  20  is suspended within the cavity of the trainer  46  between the top cover  48  and the base  50  such as from the top cover  48 . A gooseneck laparoscope holder  64  is provided on the trainer  46  to hold a scope (not shown). The scope is inserted into the trainer cavity via one of the apertures  58  or region  60  to capture video images of the obscured hernia model and display them to the user via the video monitor  54 . Users practicing hernia repair will pass other instruments in addition to the scope into the cavity of the trainer to access the hernia model inside the trainer  46 . 
       FIG. 14  is a front view of the laparoscopic trainer  46  with the first insert  56  removed to provide a view of the hernia model  10  from the perspective of the user. The combination of the hernia model  10  and trainer  46  is particularly unique because it permits hernia repair training in a laparoscopic simulation. The hernia model  10  itself simulates an insufflation cavity formed between the muscular abdominal wall and the peritoneum via the C-shaped construct and without the need for any insufflation gas in the training simulation. This C-shaped construct is resiliently held in position by the reinforced metallic mesh layer  30  which provides support to the silicone tissue features attached thereto. The metallic mesh layer  30  and silicone layers  32 ,  34  further provide a springy feel that is realistic to an abdominal wall distended outwardly by insufflation gas. The selected colors and materials employed in the anatomical portion  12  including the yellow foam for the peritoneum and the pink silicone and translucent fascia layer and bowel mimic a real live surgical situation. Because the hernia model  10  includes an anatomical portion  12  that is angled 90 degrees, the resulting visual mimics the angles encountered in a real hernia repair situation. Furthermore, the angled top cover  48  of the trainer  46  allows the tall hernia model  10  to be received with ease. Also, the angled top cover  48  further mimics the outer anterior body of the patient with an insufflated abdominal region that is enlarged in the area of the hernia. 
     The hernia model  10  combined with the angled trainer  46  provides a unique wedge-shaped approach to the target site of hernia repair via arrow  62  into a triangular or wedge-shaped cavity. This triangular shaped cavity is best seen in  FIG. 12  wherein one side of the triangle, generally the hypotenuse of the triangle, is formed by the top cover  48 . The base  50  of the trainer  46  forms the other side of the triangle that is substantially perpendicular to the hernia model  10  which forms the third side of the triangle. This triangle across the width of the trainer  46  defines a wedge-shaped cavity inside the trainer  46 . With the angle of the top cover  48  being less than 45 degrees, an elongated wedge is created having a confined approach following arrow  62  or narrow cavity near the front of the trainer  46  that expands towards the rear of the trainer  46  where the hernia model  10  is located. This wedge-shaped cavity provides for an extremely realistic, confined and challenging surgical approach for the surgeon to practice both TEP and TAPP hernia repairs.  FIG. 15  shows a view of the hernia model  10  as a surgeon practitioner would see in practice. The simulated fascia layer  20  is shown lifted by hand whereas, the surgeon practitioner would employ instruments to lift and dissect the simulated fascia layer  20 .  FIG. 15  illustrates a bowel portion  24  extending through the direct space  26 .  FIG. 16  illustrates a front view of the hernia model  10  with the simulated bowel portion  24  resected from the direct space  26  and still protruding through the opening  22  in the peritoneum  18 . 
     Turning now to  FIGS. 17-21 , there is shown another variation of the hernia model  10  where like reference numbers will be used to describe like parts. The hernia model  10  is substantially similar to the one described above and is configured for both practicing both the TEP and TAPP approaches. The model  10  of  FIGS. 17-21  has an inner surface and an outer surface and is also substantially C-shaped in which the inner surface is concave. A simulated muscular abdominal wall  16  is connected to a simulated pelvis  66 . The simulated muscular abdominal wall  16  forms approximately the top half or more of the model  10  or C-shaped curve. Instead of the bottom half or less than the bottom half of the C-shaped curve being formed by a simulated peritoneum as described above, it is formed by the simulated pelvis  66 . The pelvic base  66  is molded and is shown in the figures to represent approximately half of a human pelvis approximately lateral to the midline  45  of the anatomy to illustrate a right-sided hernia model  10 . The natural shape of the simulated pelvis  66  contributes to the curvature of the C-shape of the model  10 . The pelvic base  66  is connected to the simulated muscular abdominal wall  16  which is made of foam material and reinforced and connected to the simulated pelvis  66  with wires  70  as can be seen in  FIG. 18 . 
     The simulated pelvis  66  is covered with a first silicone layer  68 . The thin silicone layer  68  is not powdered and is cured after optionally being calendared over foam to impart the silicone layer  68  with at least one textured surface. The silicone layer  68  also covers the simulated muscular abdominal wall  16  at the inner surface. The silicone layer  68  is adhered to both the simulated pelvis  66  and to the simulated muscular abdominal wall  16  with adhesive. The silicone layer  68  is formed around, conformingly applied and adhered to the contours of both the simulated pelvis  66  and the simulated abdominal wall  16  including the first opening  26  which simulates the direct space and the second opening  28  which simulates the indirect space through which a hernia may extend. The model  10  may also be provided with a third opening that would simulate a femoral space through which the hernia may extend. The first silicone layer  68  includes two holes that are aligned with the first and second openings  26 ,  28 . A third opening is included in the first silicone layer  68  if a third opening is formed in the simulated abdominal wall  16  to simulate a femoral space. 
     With particular reference to  FIG. 19 , a variety of anatomical structures or body tissue components are overlaid onto the first silicone layer  68 . Included among them is a simulated Cooper&#39;s ligament  72 . The simulated Cooper&#39;s ligament  72  is made of a strip of silicone material that is white in color and overlaid onto the silicone layer  68 . A white tube  86  representing the iliopubic tract is laid over the silicone layer  68 . Then a simulated external iliac vein  74 , simulated external iliac artery  76 , simulated spermatic vein  78 , simulated spermatic artery  80  are overlaid onto the silicone layer  68  and over the simulated iliopubic tract  86 . A simulated epigastric vein  82  and simulated epigastric artery  84  extend upwardly from the simulated external iliac vein  74  and simulated external iliac artery  76 , respectively, and are overlaid onto the silicone layer  68 . The model  10  includes a simulated vas deferens  88  made of translucent silicone and additional nerves  90  also made of silicone that are placed over the silicone layer  68 . The end of one or more of the simulated spermatic vein  78 , spermatic artery  80  and vas deferens  88  are placed inside the first opening  26 . 
     A second silicone layer  92  is placed over the anatomical structures to sandwich them between the first silicone layer  68  and the second silicone layer  92 . The second silicone layer  92  includes two holes aligned with the two holes in the first silicone layer  68  and aligned with the first opening  26  and second opening  28 . The second silicone layer  92  includes a third hole in a variation that includes a third opening aligned with a third opening in the first silicone layer  68  and third opening in the simulated abdominal wall  16  for the femoral space: The second silicone layer  92  is wrapped around the model  10  as shown in  FIGS. 20 and 21  and attached with adhesive to the first silicone layer  68 . The second silicone layer  92  may be selectively adhered along the edges such as to the back side of the model  10  and/or to the first silicone layer  92  between the anatomical landmarks and/or to the anatomical landmarks. In one variation, the second silicone layer  92  is attached to the spermatic vessels  78 ,  80  and to the vas deferens  88 . The second silicone layer  92  is attached closely to the contours of the model  10  and the layer is formed through the first and second openings  26 ,  28  as shown in  FIGS. 17-18 . The second silicone layer  92  is translucent and thin and may include a textured outwardly-facing surface like the first silicone layer  68 . The layer  92  is unpowdered, clear, white or pink in color. 
     The model  10  further includes a third layer  94  of silicone visible in  FIGS. 20 and 21 . The third layer  94  is configured to simulate the peritoneum. The third layer  94  is also unpowdered, thin and red in color and may include a textured outer-facing surface formed by calendaring the uncured silicone between one or more foam surfaces. The third layer  94  is pushed through one of the first or second opening  26 ,  28  or through the third opening that simulates the femoral space. In  FIGS. 20-21 , the third layer  94  is shown with a portion of the third layer  94  pushed through the second opening  28  to simulate the appearance of a hernia extending through the indirect space. The third layer  94  is attached with adhesive to the rest of the model  10 . The third layer  94  is wrapped and glued around its edges to the backside of the model  10  as shown in  FIG. 21 . The third layer  94  may also be selectively adhered to portions of the underlying second silicone layer  92 . The first silicone layer  68 , second silicone layer  92  and third silicone layer  94  are all incisable with a blade and configured in thickness and tear strength to mimic real human tissue. 
     With the model  10  assembled as described, it is then inserted into the laparoscopic trainer  46  with the trainer  46  top cover  48  being angled or not angled with respect to its base  50  or with respect to a table top. The model  10  is inserted into the trainer  46  such that the concavity of the C-shape is positioned facing the first insert  56 , apertures  58 , and/or tissue simulation region  60  such that instruments inserted through these locations may readily observe or approach the concavity of the C-shape. The user will practice incising the second silicone layer  92  from the spermatic vessels,  78 ,  80  and vas deferens  88 . With the model  10  inserted into the trainer  48 , practitioners may practice resolving the hernia employing the TAPP or TEP procedures. For practicing TAPP procedures, the trainer  46  includes clips and the third layer  94  or simulated peritoneum is clipped to the surgical training device. The top cover of the surgical trainer may be angled to form an inner acute angle with respect to a horizontal plane in order to simulate a Trendelenburg positioning of the patient. The inner surface of the model faces the inner acute angle such that the inner surface of the model is approachable with instruments inserted into the internal cavity through the apertures  58  or penetrable simulated tissue region  60 . 
     The hernia model  10  of the present invention is particularly suited for laparoscopic procedures; however, the invention is not so limited and the hernia model of the present invention can be used in open surgical procedures equally effectively. 
     It is understood that various modifications may be made to the embodiments of the hernia model disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure.