Abstract
Background: In many cases, incisional hernia repair requires the use of prosthetic
materials. The aim of this experimental study in a rat model was to assess the role of polyglactin 910 mesh and fluoropassivated polyester mesh in the prevention of formation of adhesions.
Methods: In the first experiment, the formation of peritoneal adhesions was assessed
after insertion of polypropylene, polypropylene combined with polyglactin 910, or no mesh. In the second experiment, adhesion formation was compared after insertion of fluoropassivated polyester, polypropylene and no mesh.
Results: The first experiment showed no significant difference in adhesion formation
between polypropylene mesh and the combined mesh; however, when no mesh was used, There were significantly fewer adhesions in both experiments (p<0.01). The second experiment showed a significant lower degree of adhesions and a lower Adhesion Index after insertion of fluoropassivated polyester mesh than when polypropylene mesh was used (p=0.04).
Conclusions: Adding polyglactin 910 mesh to polypropylene mesh to prevent the
formation of adhesions is not an effective measure. Fluoropassivated polyester meshes could appear to provide a better alternative to the use of polypropylene meshes for incisional hernia repair in humans in terms of the formation of adhesions.
Mesh for Incisional Hernia Repair
5.1 Introduction
Incisional hernias occur in 11 % of patients after laparotomy. Repair of these hernias frequently requires the use of prosthetic materials. Polypropylene mesh is commonly employed for this purpose [Leber 1998, Molloy 1991]. There is some concern among surgeons about the use of prosthetic material because of the risk of infection of the mesh, the formation of enterocutaneous fistulas and the development of adhesions between the viscera and the mesh. To prevent fistulas and adhesions, some authorities recommend that the parietal peritoneum be preserved during incisional hernia repair because it forms a barrier between the viscera and the mesh. When the parietal peritoneum cannot be kept intact, the surgeon may attempt to place the greater omentum between the abdominal contents and the prosthetic material.
However, in daily practice, it is often not feasible either to preserve the parietal peritoneum or to use the greater omentum. In these cases, some surgeons insert a resorbable polyglactin 910 mesh between the intestines and the polypropylene mesh or use a composite of polyglactin 910 and polypropylene meshes. Alternatively, ePTFE (expanded polytetrafluoroethylene, Gore-tex) meshes, which supposedly induces fewer adhesions, or human tissue such as dura can be employed; however, these alternatives are costly.
The search for new biomaterials for incisional hernia repair has resulted in the development of fluoropassivated polyester. Fluoropassivation of the polyester surface is expected to diminish the formation of adhesions. The cost of fluoropassivated polyester meshes is comparable to that of polypropylene meshes. We performed two experimental studies in rats to evaluate the role of polyglactin 910 and fluoropassivated polyester in the prevention of the formation of adhesions.
5.2 Materials and methods Animals
Female Wistar rats of reproductive age weighing 200-250 g were obtained from Harlan, Zeist, The Netherlands. They were bred under specific pathogen-free conditions and kept under standard laboratory conditions (temperature, 20-24°C, relative humidity, 50-60%, 12 h light and 12 h dark). The rats were given standard rat chow and water ad libitum. The experimental protocol adhered to rules laid down by the Dutch Animal Experimentation Act and was approved by the Committee on Animal Research of Erasmus University, Rotterdam.
Prosthetic material
The evaluated prosthetic materials were nonabsorbable polypropylene mesh in a double-filamented form (Prolene; Ethicon Inc., Somerville, NJ, USA), absorbable polyglactin 910 mesh (Vicryl, Ethicon Inc, Somerville, NJ) and nonabsorbable multi- filament fluoropassivated polyester mesh (Fluorosoft; Sulzer Vascutek Ltd., Renfrewshire, Scotland). Fluoropassivated polyester was developed to combine the strength, handling, and healing characteristics of polyester with the inertness and biocompatibility of expanded polytetrafluoroethylene (ePTFE, Gore-Tex; W.L. Gore, Flagstaff, AZ, USA). It is more resistant to bacterial binding than polypropylene [Kelso 1997]. The price of fluoropassivated polyester mesh is considerably lower than that of ePTFE mesh. In the Netherlands, ePTFE mesh costs $365-$820
depending on size and number of pieces required, whereas a fluoropassivated polyester mesh costs $100-$125 and a polypropylene mesh costs $35-$70.
Model
The experiment was executed in a validated uterus horn model in the rat, allowing semiquantitative scoring of adhesions according to Van den Tol et al. [1997] and
Bakkum et al. [1994]. In the rat the uterus horn is a Y-shaped structure with two
horns of approximately 4 cm length. Under ether anesthesia and aseptic but not sterile conditions, the abdomen was shaved and cleaned with alcohol. Laparotomy was performed using a lower midline incision of 5 cm. Bilaterally, 1.5 cm downwards from the abdominal incision, a mesh of 1.5 x 1.0 cm was positioned between the uterus horn and the abdominal wall and then sutured to the abdominal wall with three 5.0 Surgilene sutures at 0.7 cm intervals (Fig 5.1).
Figure 5.1 The mesh was fixed to the lateral abdominal wall with three
sutures 0.7 cm apart. Then the uterus horn that was previously rubbed with gauze was tightened to the abdominal wall without strong tension
Standard surgical trauma to induce adhesion formation [Thompson 1965] was inflicted on the uterus horn by rubbing it with a surgical gauze using a device enabling the application of a constant pressure of 120 g/cm2. The uterine horn was rubbed ten times over its total length, then tightened to the lateral abdominal wall with two 5.0 Surgilene sutures. If a mesh was inserted between abdominal wall and uterus horn, it was fixed with the three 5.0 Surgilene sutures. This procedure was performed bilaterally.
ovarium