Abdominal wall closure after selective aponeurotic incision and undermining.

The tension required to pull the anterior and the posterior rectus sheaths toward the midline was studied in 20 fresh cadavers at two levels: 3 cm above and 2 cm below the umbilicus. The quotient of the force used to mobilize the aponeurotic site to the midline and its resulting displacement was called the traction index. These indices were compared in three situations: (1) prior to any aponeurotic undermining, (2) after the incision of the anterior rectus sheath and the undermining of the rectus muscle from its posterior sheath, and (3) after additionally releasing and undermining the external oblique muscle. A significant decrease in aponeurotic resistance was observed after each dissection. The anterior sheath showed higher resistance to traction compared with the posterior sheath on both levels. No statistical difference was noted in the comparison of the values of the aponeurosis above and below the umbilicus. These results suggest that these procedures are effective in assisting in the closure of abdominal wall defects because these maneuvers decrease substantially the tension required for advancement of the aponeurotic edges.