Experimental-morphological justification of the effectiveness for the connective tissue carcass formation in the anterior abdominal wall depending on the topographic-anatomical graft implant location

Abstract

The aim — to study morphometric characteristics of the formation of connective tissue skeleton, depending on the location of the mesh between the different anatomical structures of the anterior abdominal wall.Materials and methods. An experiment was performed with 30 adult chinchilla rabbits, which had undergone implantation of a polypropylene mesh sterile pieces (PROLEN, Ethicon) of size 1.0 ´ 1.0 cm in the anterior abdominal wall lateral area. All studied animals were divided into 3 groups depending on the place of the mesh implantation: preperitoneal (n = 10), intramuscular (n = 10) and subaponeurotic (n = 10). The tissues of the anterior abdominal wall sized 1.5 ´ 1.5 cm were sampled on the 7th, 14th, 21st, 28th and 35th day after implantation. To assess the effectiveness of the connective tissue framework formation, depending on the topographic location of the implant, a morphometric study with following parameters was performed: relative area of collagen fibers, relative amount of collagen fibers with a fiber thickness more than 10 µm and less than 10 µm, the relative area of the cell component.Results and discussion. It was established that the scar tissue formation after the mesh implantation has significant differences depending on its localization. In the area of the peritoneum and the muscle the mesh implantation induced reactive changes, manifested by granulation tissue formation, rich by non­differentiable vessels, the structure of which fibrocytes and fibroblasts was dominated. Up to 21 day the connective tissue scar is formed from dense bundles of collagen fibrils. Up to 28th — 35th day a further connective tissue maturation processed, fibroblasts number reduced, the fibrous structures number increased. The mesh threads were embedded in connective tissue fibers, the strands of mature connective tissue formed between the threads, but thinner than in the filaments locations. Aponeurotic mesh implantation caused a somewhat different reaction. The signs of edema and the fibrous structures formation around and between the threads were expressed on the 7th day in the aponeurosis area. A solid layer of mature connective tissue with a large fibers and fibroblasts number was formed on the 21st day. The thickness of the scar was 5 — 6 times higher than in the muscle and peritoneum. The predominance of the fibrillar component of scar tissue over the cell, mature collagen fibers over the young fibrous structures was observed on the 21st day of the experiment, that confirmed the earlier initiation and high rate of peri­implant reparative­proliferative processes for the subaponeurotic mesh implant in comparison with preperitoneal and intermuscular ones.Conclusions. The obtained experimental data allow to postulate a better morphometric and histological characteristic of the scar formation in case of subaponeurotic mesh placement that is important for the surgical approach choice. The study results substantiate the morphological improvement of existing treatment methods in patients with a considerable distraction of aponeurotic edges with postoperative ventral hernias, as a remote complications of gunshot peritonitis surgical treatment.