Prosthetic Materials and Adhesion Formation

Abstract

Fibrovascular adhesions are found in 50 to 95{%} of patients who have undergone open abdominal surgery.I-3 Mechanical trauma, thermal injury, infections, tissue ischemia, and foreign materials are the most important contributing causes of adhesion forma-tion. 4 Foreign bodies have been reported in 61 to 69{%} of post-operative adhesions. In 50 to 68{%} of cases the foreign material was talc; other materials included sutures, cotton lint, filaments from dressings, starch, extruded gut contents, and prosthetic im-plants. Combinations of different materials have also been noted (usually talc and thread).2.5 The common pathway leading to adhesion formation is in-flammation, which produces exudates containing high quantities of fibrinogen. 6--8 Fibrin clots develop and cause adhesions, at least temporarily, between surfaces otherwise unattached. Granulation tissue results after colonization of the fibrin network by fibroblasts, macrophages, and new blood vessels. A healthy and well-vascular-ized peritoneum has an effective fibrinolytic system due to a plas-minogen activator, which is able to completely absorb the newly developed fibrinous attachments. 4 • 9 Prosthetic materials can con-siderably impair the fibrinolytic activity by two different mecha-nisms: 1. Tight suturing and grafting induce peritoneal ischemia. Is-chemic tissues are potent stimuli to adhesion formation and ac-tively inhibit fibrinolysis in adjacent peritoneal tissue. 6 .8-11 Thus, retention of vascularization is essential for proper, adhesion-free peritoneal healing.6.I2.I3 2. Mesothelial cell proliferation seems to be another inhibitor of adhesion formation 14 .I5; its reduction, observed in infected wounds and in those where a prosthetic mesh is applied, cor-responds with a decreased fibrinolytic activity.I5 A number of experimental and clinical studies have been con-ducted to better understand the mechanism of adhesion forma-tion and prevention. One of the major difficulties encountered has been the development of an animal model that could be re-producible, quantifiable, and reliable. The rabbit uterine horn model has gained widespread popularity.I6 This model involves a traumatic deperitonealization of the rabbit uterine horn. The re-sulting raw surface can develop adhesions with other raw surfaces within the abdominal cavity in approximately 2 weeks.