Static calculations for mesh fixation by intraabdominal pressure in laparoscopic extraperitoneal herniorrhaphy

In laparoscopic extraperitoneal herniorrhaphy, there have been no static calculations for nonfixed prostheses with regard to the ideal size of the prosthesis, mesh overlap on the hernial orifice, friction coefficient, and shear forces. The aim of the present study was to perform these static analyses. The friction coefficient of a polypropylene mesh was measured in an experimental setting. Based on the distribution of adhesive force and load on the mesh, we calculated the required mesh overlap over the hernial opening. The friction coefficient was determined as mu0 = 0.3. The friction surface required to immobilize the prosthesis is 4.16 times the stress surface. Assuming a safety factor of 2.5, the minimum distance between the margin of the prosthesis and that of the hernial opening should be equal to the diameter of the hernial opening. For smaller lesions we recommend a minimum mesh overlap of 2 cm over the hernial orifice. From a hernia size 2 cm and larger, the distance between the margin of the prosthesis and the hernial opening should be equal to the diameter of the orifice. From 4 cm and larger, the prosthesis should be secured with a stapler (or a similar mode of fixation) to prevent recurrence.