Measurement of the tensile strength of the ventral abdominal wall in comparison with scar tissue.

BACKGROUND: Paramedian laparotomies lead to incisional hernias in approximately 30% of cases. In contrast, incisional hernias occur very rarely in the linea alba or the ventral abdominal wall. In this setting we investigated the difference between scar tissue and the non-incised abdominal wall tissue.
METHODS: At the post mortem examination of 66 recently deceased individuals, accurately measured pieces of resected tissue from the linea alba, the anterior and the posterior rectus sheath, and scar tissue following median laparotomy, were exposed to tensile loads.
FINDINGS: In the epigastric region the tissue ruptured at a mean horizontal load of 10.0 (SD 3.4) N/mm(2) in the linea alba and 6.9 (SD 2.5) N/mm(2) in scar tissue (P<0.001), and at a mean vertical load of 4.5 (SD 2.0) N/mm(2) in the linea alba and 3.3 (SD 1.6) N/mm(2) in scar tissue (P<0.05). In the hypogastric region as well, scar tissue was significantly less resistant in the main direction of load.
INTERPRETATION: Scar tissue has a significantly lesser loading capacity than the intact ventral abdominal wall and therefore poses a permanent risk for herniation. For this reason, closure of the abdominal wall should be given due consideration and subjected to further investigation. Specifically, sustained reinforcement of scar tissue by means of suture techniques or non-absorbable sutures warrants further study. When constructing meshes for reinforcement of incisional hernias, the two-fold tensile load on the midline in horizontal direction as opposed to the craniocaudal direction must be taken into account.