Mechanical characterization of endoscopic surgical staples during an experimental hernia repair.

Recent developments in laparoscopic hernia repair techniques have led to the design of titanium staples. In a laparoscopic hernia repair, a polypropylene mesh is stapled over the direct and indirect hernia sites in the inguinal region. The effectiveness of these staples in holding the prosthetic mesh, and therefore providing adequate strength to the abdominal wall, has not been yet investigated. We have characterized the bursting strength (BS) of an experimental hernia mesh repair fixed with Prolene suture, which is used extensively for this procedure, and the BS of repairs fixed with two currently available staplers, the Endopath EMS endoscopic multifeed stapler and the Endo Hernia stapler. We first simulated abdominal wall hernias in 16 piglets by creating incisions on both sides of the abdomen of each animal. Each defect was then covered with a polypropylene mesh, which was fixed on one side with Prolene sutures and on the other side using either the Endopath EMS (Group 1) or the Endo Hernia stapler (Group 2). The abdominal tissue with the mesh covering the defect was then excised and the BS evaluated using an Instron machine. Since many mechanical characteristics contribute to the BS of a repair, we investigated these characteristics in vitro, including tensile properties of the staples and the prosthetic mesh as well as the suture-tearing resistance of the mesh. Polypropylene mesh exhibits the same elongation in the three directions, i.e. 0 degrees , 45 degrees and 90 degrees . This elongation was estimated at 136% (SD = 130).(ABSTRACT TRUNCATED AT 250 WORDS)