Polydioxanone weft-knitted intestinal stents: fabrication and mechanics optimization

This paper presents the fabrication of polydioxanone weft-knitted stents and the mechanical properties optimization on process parameters. The stents can be used for treatment of intestinal obstruction and stenosis. Patients diagnosed with different phases require different mechanical stents. So, the mechanical properties of stents, radial force and circumferential strength are important for the safety and efficiency of stents. The aim of this paper was to identify the effect of process parameters on the mechanical properties of stents using the statistical modeling method, then propose optimum parameter settings. The intra-abdominal and intra-intestinal pressures of the human intestine were investigated through an intestine physical model; a full factorial experiment was employed to identify the most suitable factors and find the optimum processing parameters according to the two pressures identified. The results showed that optimum stents with radial force in the range of 1.3-2.5cN/mm and circumferential strength in the range of 20-50cN/mm could be obtained at a stitch cam setting ranging from 3.2 to 3.4mm, with fabric tension in the range of 140-160cN if the yarn tension and yarn linear density were held at 1.2cN and 150 tex, respectively. The model validation results showed that stents with different mechanical properties could be tailored through the statistical method and proposed model. In conclusion, such stents, and optimization method, may find broad applications clinically.