Introduction

The hernia word designates an organism portion dislocating throughout a natural or acquired cavity. The inguinal or perineal herniation is frequent, resulting from pelvic diaphragm and abdominal cavity muscular wall defects, mainly intestinal loops and/or urinary vesicles, although hernia can present themselves in different positions in the abdominal cavity as well as in the thoracic region, insinuating throughout diaphragm (Waldrom et al. 1986). Reducing hernia reappearance has been a challenge (Read 1984). The search for biocompatible prosthesis to correct anatomical imperfections has begun in 1894 using silver row "tissue" (De Debord 1998). Metallic tissue were substituted for more flexible and shapely materials such as Fortison, polyvinyl, "nylon", silicone, Teflon, carbonate fiber, polyester, polypropylene, polytetrafluorethylene (PTFE) and polyglycolic acid (Dexon) (Scales 1953). The polypropylene prosthesis introduced in Brazil, in 1969 by Falci, are the most used in our environment avoiding excessive tension in the aponeurotic border suture line (Lichtenstein 1989). The incisional hernia recurrence rates after corrections by primary repairs vary from 10% to 50% (Kather 1997), while using prosthesis they occur from 3% to 17% of the cases (Usher 1962). According to Arnid (1997) the best results for complex hernia treatment are obtained with prosthesis reinforcement. Meanwhile, complications can emerge, such as intestinal fistulas, inflammatory reactions and chronic pain (Losanoff 2002). The aim of this paper is to evaluate the efficacy of nylon tissue fixed with absorbed row (cat gut n° 3-0) correcting imperfections in dog's abdominal wall, verifying the recurrent incidence.

Material and Methods

There have been used 8 healthy dogs, with no defined breed, both sexes, adults, with weight varying from 5 to 15kg, proceeding from the Zoonoses Control Center of Uberlandia, Minas Gerais, Brazil. The animals were housed in individual dog-houses where received commercial food and water ad libitum. After abdominal trichotomy the dogs were induced and maintained in anesthetics plan with ketamine chloridrate (10mg/kg) associated to xylazine (1mg/kg) administered intramuscularly. The pre- surgical protocol is constituted by antibiotic therapy with sodium cefazolin (30mg/kg), flunixin meglumine application as antiinflammatory (1mg/kg) and anti sepsis with a 10% pyrrolidone polyvinyl solution. In each animal were produced a ventral incisional hernia in the medial retro umbilical region, incising skin, subcutaneous tissue and linea Alba, with approximately 10cm extension, such as the developed model by Aydos et al (1997). After these procedures, the hernia was reduced throughout adjust and fixation of the "nylon" tissue at the peritoneum and muscles, using simple isolated dots and 3-0 chromed cat gut row. The implant was recovered with subcutaneous tissue (zigzag suture with 3-0 chromed cat gut row) for abolition of the dead space and the skin synthesis (isolated simple pattern with 3-0 "nylon" row), ended the surgical procedure. The post surgical protocol consisted in antibiotic therapy with sodium cefazolin (30mg/kg 8/8hr/ 7 days), flunixin meglumine application as anti-inflammatory (1mg/kg/5 days) and daily curative with 0,9% saline solution. At the 21st post surgical day, the dogs were anesthetized again and submitted to laparotomy to macroscopic evaluations and incisional biopsies at the implant region. The experiment was executed following the rules from the institution ethic committee.

Results

During the 21 days of post surgical clinical accompaniment there weren't any recurrence of the reduced hernias using "nylon" tissue implants. Neither was observed, inspecting the abdominal cavity through laparotomy, presence of transudates, exudates, fistula or any other signal of dehiscent or rejection to the prosthesis. In non cases adherence was registered among the prosthesis and abdominal viscera, although in all of them the omentum adhered to the implanted "nylon" tissue. It has been noticed the presence of granulation tissue with neovascularization characteristics in 100% of the lesions.

Discussion and Conclusions

The primary aponeurotic suture done at the median line is the most simple and anatomic technique to abdominal cavity closing, although produces an elevated tension on the suture line, predisposing to dehiscence and post surgical complications such as infection on the surgical wound, peritonitis and significant incisional hernia incidence (Yeh et al. 1996). In the present investigation there wasn't registered dehiscence, infections, peritonitis or incisional hernia recurrence, proving the biocompatible character and the resistance of "nylon" implant used in abdominal incisional hernia reduction. According to Swift et al (1999), studies demonstrated the collagen concentration in cutaneous wounds, conferring resistance to them. In this study it has been observed granulation tissue with peculiar angiogenesis infiltrating in the implant, indicating the prosthesis incorporation to the tissue and consequent maintenance and/or increment of the resistance and integrity of the abdominal wall. The "nylon" tissue prosthesis used to correct abdominal incisional hernias integrated to the abdominal musculature, promoting the necessary resistance to prevent recurrence.

References

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