Evaluación y caracterización de las mallas de polietileno de alta densidad para su uso como implantes en cirugía veterinaria

Abstract

The use of synthetic materials such as polypropylene mesh for hernia repair in animals has been known for some time, but has not spread enough among veterinary surgeons. Because the high-density polyethylene (HDPE) has similar characteristics to polypropylene (PP) for surgical use in humans, this study was planned in order to assess its suitability for use as a synthetic implant to resolve quickly and efficiently hernias in animals with the significantly lower cost care advantage. In order to compare the systemic and organic effects of this materials (PP and PE), an experimental study was conducted in rats (Rattus norvegicus albinus) in accordance with national and international regulations regarding the ethical use of experimental animals. 18 Wistar rats were surgically implanted of 1 cm ² PP mesh into the left flank (control) and of 1 cm ² HDPE mesh in the right flank (experimental). They were sacrificed at day 14 (n = 5), 28 (n = 5), 42 (n = 4) and 56 (n = 4) post-implantation and cutted out the mesh and surrounding tissue for histological processing with hematoxyline and eosine. All animals healed favorably and none of them showed signs of systemic disease or rejection of the implant. There were no significant differences (p <0.05) in response to PP or HDPE for the following cells: neutrophils, plasma cells, lymphocytes, mast cells, eosinophils and basophils. For fibroblasts, significant differences (p <0.05) between PP and HDPE at 14 days were found; but afterwards they remained equal in the inflammatory response. Whith regard to macrophages, the only statistically significant difference (p <0.05) was found in the final stage of the period (56 days). Our results indicate that a chronic inflammatory reaction was similar in both treatments (PP and HDPE); therefore, no impediment was found to replace the use of PP by HDPE in the surgical repair of hernias. We subsequently proceeded to the resolution of clinical cases of hernias using HDPE as a substitute for PP. Initially, the dissection of the perineal region of 256 formalin-fixed canine cadavers and 18 fresh canine carcasses was performed to recognize each of the anatomical structures. 46 male dogs with perineal hernia and 1 dog with inguinal hernia, and a cat with post-castration abdominal hernia were surgically treated. Routine analysis was performed and patients were stabilized 9.-SUMMARY 225 before proceed to surgery in order to achieve the synthesis of hernia using HDPE mesh. All animals evolved favorably, showing a moderate swelling the first few days. In postoperative controls, one patient with local infection at the periphery of the mesh, which was quickly resolved with the cleaning up of the area and antibiotics, was recorded. Not recurrence, or fistula, or rejection of the implant were recorded, in terms of controlling 3 years on average with a range from 6 months to 7 years; and no sign or symptom that contraindicate, so far, the use of this material was observed; so we conclude that the HDPE mesh integration into the tissues was complete in all surgically treated cases, and it remained in situ for a long term. Considering that the higher prevalence of perineal hernia is seen in the elderly animals, and the risks to which the animal faces, derived from the anesthetic and surgical times; the efficiency and speed that demonstrates our technique of placing the mesh makes it ideal for treatment of this disease. For all the above reasons, the use of HDPE mesh is recommended for surgical treatment of canine perineal hernia and, although mostly applied to perineal hernias in our study, as these are the most difficult to solve, the use of high density polyethylene may be extended to any other hernias, applied in correcting defects and injuries in various surgical procedures, and used in other animal species. We conclude, on the basis of the excellent results obtained in both laboratory animal testing and in clinical cases, that the use of HDPE mesh is a good alternative and could replace polypropylene, for surgical treatment of hernias.