PRIMARY SPHINCTEROPLASTY COMPARING TWO DIFFERENT STITCHES IN ANAL FISTULA TREATMENT: EXPERIMENTAL STUDY IN RATS.

BACKGROUND: Anal fistula is by definition the communication between the rectum or anal canal with the perineal region, which may be epithelialized and has cryptoglandular origin in 90% of cases. There are a large number of techniques for successfully treating trans-sphincteric fistulas of 20-50%, including primary sphincteroplasty, but it is not clear whether the material used would influence the outcome. AIM: To analyze the efficacy of polydioxanone and polypropylene wire in primary post-fistulotomy sphincteroplasty in the treatment of trans-sphincteric fistulas in rats. METHODS: Thirty Wistar rats had transfixation of the anal sphincter with steel wire, which remained for 30 days for the development of the anal fistula. After this period, it was removed and four groups were formed: A (control) without treatment; B (fistulotomy) submitted to such procedure and curettage only; C (polidioxanone) in which sphincteroplasty was performed after fistulotomy with polydioxanone wire; D (polypropylene) submitted to the same treatment as group C, but with polypropylene wire. After 30 days, euthanasia and removal of the specimens were performed for qualitative histopathological analysis, measurement of the area between the muscular cables edges and evaluation of the degree of local fibrosis. RESULTS: There was persistence of the anal fistula in all animals of group A. There were no significant differences between groups B, C and D regarding the distance of the muscular cables (p=0.078) and the degree of fibrosis caused by the different treatments (p=0.373). CONCLUSIONS: There was no difference between polydioxanone and polypropylene wires in post-fistulotomy primary sphincteroplasty, and this technique was not superior to simple fistulotomy in relation to the distance of the muscular cables nor did it present differences in relation to the degree of local fibrosis.

Evaluation of polypropylene and polyglactin sutures in primary sphincteroplasty for the treatment of anal fistula in rats / Avaliação dos fios de polipropileno e poliglactina na esfincteroplastia primária no tratamento da fístula anal em ratos

ABSTRACT Rationale: Fistulotomy followed by primary sphincteroplasty is one of the therapeutic options in transsphincteric fistulae; however, it was not known which suture would present a better result. Objective: To compare polypropylene and polyglactin sutures in primary sphincteroplasty in rats subjected to fistulotomy. Method: Thirty Wistar rats were subjected to peritoneal anesthesia with ketamine and xylazine, followed by transfixation of the anal sphincter with steel thread, which remained for 30 days to develop the anal fistula. After this period, the steel thread was removed and four groups were formed: A - Control (n = 5), without treatment; B - Fistulotomy (n = 5), performed fistulotomy only; C - Polypropylene (n = 10), in which fistulotomy was performed followed by primary sphincteroplasty with polypropylene suture; D - Polyglactin (n = 10), in which fistulotomy was performed followed by primary sphincteroplasty with polyglactin suture; after 30 days the animals were anesthetized again and submitted to euthanasia by deepening the anesthetic plane to remove the specimens, analyzing fistula closure, muscle fiber distance, and inflammatory process. Results: The fistula persisted in all animals of the control group and in none of the other groups; the distances between the muscle fibers were 1620 µm, 4665 µm, and 2520 µm, respectively in Groups B, C, and D (p = 0.067); in relation to fibrosis, the means were 2.4, 2.8, and 3.6, respectively in Groups B, C, and D, showing greater fibrosis in the latter group (p = 0.041). Conclusion: There was no persistence of the fistula in any of the treated animals; there was no difference in the distance between the muscle fibers between the groups subjected to primary sphincteroplasty with polypropylene or polyglactin, or between these groups and the one treated only by fistulotomy. There was greater fibrosis in animals treated with primary sphincteroplasty with polyglactin.

RESUMO Racional: A fistulotomia seguida de esfincteroplastia primária é uma das opções terapêuticas nas fístulas transesfincterianas, porém, não se sabe ao certo qual fio poderia apresentar melhor resultado. Objetivo: Comparar os fios de polipropileno e poliglactina na esfincteroplastia primária em ratos submetidos a fistulotomia. Método: Utilizou-se 30 ratos Wistar, confeccionada fístula por transfixação do esfíncter anal com fio de aço, que permaneceu por 30 dias. Após, o fio de aço foi removido e foram formados quatro grupos: A - Controle (n = 5), sem tratamento; B - Fistulotomia (n = 5), realizada fistulotomia apenas; C - Polipropileno (n = 10), em que foi realizada fistulotomia seguida por esfincteroplastia primário com fio de polipropileno; D - Poliglactina (n = 10), mesmo procedimento com fio de poliglactina; após 30 dias analisou-se o fechamento da fístula, afastamento dos cabos musculares e processo inflamatório. Resultados: A fístula persistiu em todos animais do grupo controle e em nenhum dos demais grupos; dos grupos tratados a área de afstamento dos cabos musculares foi 1620 µm, 4665 µm e 2520 µm, respectivamente nos Grupos B, C e D (p = 0,067); em relação à fibrose as médias foram 2,4; 2,8 e 3,6; respectivamente nos Grupos B, C e D, demonstrando maior fibrose neste último grupo (p = 0,041). Conclusão: Não houve persistência da fístula em nenhum dos animais tratados, não houve diferença no afastamento dos cabos musculares entre os grupos submetidos a esfincteroplastia primária com polipropileno ou poliglactina, e nem destes com o grupo tratado apenas por fistulotomia. Houve maior fibrose nos animais tratados por esfincteroplastia primária com poliglactina.