Drainage Efficiency Analysis of Different Hanging Structures for High Anal Fistula Surgery

Hanging thread drainage is a treatment for high anal fistula surgery, which mainly caused Crohn disease and has the potential perianal infection risk. By the manner of draining the tissue fluid exuded from the wound, hanging thread drainage would facilitate healing of the wound. However, the chosen of hanging structures is mainly comes from medical experience, and there is a lack of uniform standard. In this paper, the drainage efficiency of different hanging structures is studied. A typical anal fistula wound with hanging thread is modeled in SolidWorks according to the measured data of 4 patients. The viscosity characteristic of tissue fluid is tested by experiments. By the method of controlling variables, different models related to different thread material, cross-section shape and cross-section area are simulated by FLUENT. The results comparison show that: (1) In the case of the same material and same cross-section area, the drainage efficiency of circular section is better than that of square Sect. (2) In the case of the same material and same cross-section shape, the drainage efficiency of larger cross-section area is better than that of smaller cross-section area. (3) In the case of the same cross-section area and same cross-section shape, the surface roughness is applied to characterize the thread material, and the drainage efficiency of material with larger surface roughness is better than that of smaller surface roughness material. The conclusion of this paper can provide a theoretical reference for the chosen of hanging structures in the high anal fistula surgical scheme.