Ali M Linsk, MD1, Darren S Tavernelli, RN, RRT2, Michael McBride, BSN2, David Fobert, BA, ALM2, Daniel Jones, MD, MS, FACS3, Steven D Schwaitzberg, MD, FACS4. 1Cambridge Health Alliance, Beth Israel Deaconess Medical Center, 2Beth Israel Deaconess Medical Center, 3Beth Israel Deaconess Medical Center, Harvard Medical School, 4Cambridge Health Alliance, Harvard Medical School
We developed a correlate to the FLS pattern cutting task to assess transfer of learning from the FLS task to a more clinically orientated surrogate. Our objective was to build a low-cost, robust hernia simulator, with the initial focus on the first step of a (TAPP) hernia repair, the creation of a peritoneal flap.
Our model uses a piece of heavy-duty plastic obtained from a large trashcan that is curved to mimic the size and shape of the human abdomen and pelvis. A frame is placed around the edges of the plastic to maintain the desired curvature and it is then secured to a wooden base on three sides. A hinge mechanism is placed to keep the fourth side mobile and to provide access to the inside of the simulator so that the materials can be easily manipulated in between trials.
Trocar sites are created in the plastic and a piece of material that is smooth on the top side and foam on the bottom side is attached along the outside of the plastic as the abdominal skin. Corresponding holes for the trocar sites are placed through the skin. We designed a rectangular silicone mold to serve as a model of a left-sided pelvis. The mold is glued into the inside of the plastic in the anatomical location of the left pelvis. Plastic tubing of different sizes, shapes and colors is implanted into the mold to mimic the following anatomical structures: the medial umbilical ligament, the inferior epigastric vessels, the spermatic vessels/round ligament, the internal inguinal ring, the femoral vein, Cooper’s ligament, and landmarks for indirect, direct, and femoral hernia defects.
Power Mesh, a stretchy fabric, often used to make bathing suits, is then treated with silicone and cut into pieces that match the size of the mold. This serves as the peritoneum and adheres well to the mold to allow for visualization of the landmarks just behind the peritoneum. The peritoneum is clipped in place for extra security. The user will incise the peritoneum starting at the medial umbilical ligament and simulate the TAPP incision used clinically based on the simulator landmarks. The user will need to be sure to place traction on the peritoneum with their dissector in order to cut only through the peritoneum and not into the abdominal wall or vessels.
Our next stage of development is to design the molds and materials for the remaining TAPP steps: identification and dissection of the hernia sac, placement of the mesh, and closure of the peritoneum. We will use our prototype to develop a right-sided model and merge the two together to create a comprehensive bilateral laparoscopic hernia simulator. This simulator will provide unique training opportunities for medical students and residents and cost less than $125 to build.