Biomechanics of the Abdominal Wall In case of disturbed integrity of the abdominal wall, activities of daily life such as coughing, urination and defecation are seriously hampered. For these functions, an even contraction of all muscles of the abdominal wall is needed to increase the pressure in the inner abdominal space. This might be disturbed if the arrangement of the muscular structures is broken up. The tension in case of contraction is a great strain for the individual structures of the abdominal wall. The wellknown weak points are the groin, the navel and scar tissue, where the connective tissue tends to yield and move apart. Soft tissue ruptures in the abdominal wall are caused by tensile loadings resulting from abdominal muscle activity which the abdominal wall is not able to withstand. The anatomical features of the groin and the navel clearly show that their stress resistance is very low while the low stress resistance of scar tissue can be easily explained by its tissue consistency. Therefore, hernias occur in up to 30% of cases of primary laparotomy closures, and the treatment of incisional hernias is also associated with a high recurrence rate. Our static and dynamic studies show that even a primary abdominal wall closure after median laparotomy requires reinforcement. Furthermore, our study shows that the position of the mesh in relation to the abdominal wall structures is of secondary importance for reinforcement of the tissue (onlay versus sublay technique). However, the width of the mesh overlap is one of the determinants of a recurrent hernia. Therefore, the width should be adjusted to the size of the hernial opening. The fixation of the mesh in the tissue is also very important; nearly all recurrent hernias are caused by the mesh’s separation from the tissue.