Mesh augmentation in abdominal wall repair. How much is enough?

Incisional hernia is one of the most frequent long-term complications after abdominal surgery, with an incidence of 2-20% in the general patient population. In high risk patients (i.e. morbidly obese and people with abdominal aortic aneurysm), incidence can increase to more than 30%.

Other known risk factors for poor wound healing include smoking, hypoproteinemia, anemia, malignant disease and wound infection.Incisional hernia can cause morbidity and can have a negative effect on patients’ quality of life and body image. Furthermore, there is a risk of bowel obstruction and strangulation and perforation. For these reasons, incisional hernia repair is a frequent surgical procedure. Even though repair with mesh reinforcement has a lower risk of recurrence compared with primary suture, the recurrence rate is high still.The use of laparoscopic techniques has not yielded better results with respect to recurrence of incisional hernia and in some cases, midline laparotomy is unavoidable. Many studies have evaluated different types of incision, suture materials, and closure techniques to reduce the incidence of incisional hernia.Several randomized controlled trials suggest that mesh-augmented repair is feasible and effective in the treatment and prevention of incisional hernias after midline laparotomy, especially in high-risk patients.

Regarding mesh size, it is rarely discussed in clinical studies. Papers that discuss mesh size appear to comply with the recommendations to use larger mesh to decrease the chance of recurrence due to insufficient coverage or mesh retraction. Clinical studies have been published on inguinal hernia repair suggesting an ideal size, but results vary widely. Experimental studies do suggest that a mesh should overlap the wall defect by 3cm or more.

Regarding mesh integration, it depends on the tissue reaction to the biomaterial and it plays an important role in the success of the repair. In fact, the role of fixation sutures or adhesives is to hold the mesh in place while it integrates. Once the mesh is integrated to the surrounding tissue, mesh contraction and migration decrease.

Mesh contraction and migration following implantation can occur after hernia repair and are both associated with hernia recurrence. Regardless of the mesh composition, all undergo retraction. Studies show that mesh that detaches from the fixation points presents the greatest contraction, as it begins before it can start to integrate into the tissue. Other factors that influence the inflammatory reaction are the characteristics of the mesh and size of the mesh surface in contact with the tissue. The larger the pores are, the faster the tissue ingrowth resulting in less contraction. The smaller the quantity of biomaterial is, the lesser the inflammatory reaction and less shrinkage.