Page 151 - Prevention and Treatment of Incisional Hernia- New Techniques and Materials

seen to the right (contralateral) side of the colostomy. In addition di erences were observed in the thickness of the ARM in the area near the colostomy.In literature, a decrease of the general thickness of the ARM in females and in older people has been described, and similar ndings were observed in this study (20, 21). Little is known, however with regard to the e ect of abdominal incisions on changes in the abdominal wall and even less is known regarding changes after colostomy creation (15, 22, 23). Two types of changes in the abdominal wall were observed in this study which might have an in uence on wound healing and IH formation.
Midline shift
A signi cant shift to the contralateral side of the colostomy was observed when preoperative and postoperative CT-scans were compared. The observed midline shift appears to be caused by a decrease in restraining forces at the site of the colostomy. Without the pull of the abdominal wall muscles on the left (colostomy) side, a dysbalance of the muscles in favor of the muscles on the right (contralateral) side can result in the observed midline shift. This change would increase the force on some parts of the suture line. In addition, a curve instead of a straight wound line will also promote separation of the wound edges which is known to be a risk factor for IH (13). Although it is possible that in addition to the decrease in restraining forces, the excess of tissue due to colostomy creation might also induce a shift, this could not be tested in this study. During our initial mechanical modelling by testing using the Abdoman®, (the arti cial abdomen of Erasmus University Medical Center and Technology University of Delft, the Netherlands) we observed that a midline shift also occurred without the excess volume of a colostomy and that the decrease in restraining forces were the main cause of midline shift. This ndings are, however, preliminary and more research still needs to be conducted.
ARM measurements
Other observed ndings were changes in ARM thickness. The left (colostomy) ARM at the level of the colostomy was signi cantly thicker postoperatively compared to the preoperative situation. On review of the CT-scans, it was more di cult to measure the ARM thickness in the vicinity of the colostomy; the medial part of the ARM seemed to fold over itself due to pressure of the colostomy, inducing the apparent observed increase in thickness.
7
Abdominal wall changes and IH
149