Design, manufacture and evaluation of a NiTi stent for colon obstruction.

We have designed, manufactured and evaluated a prototype of a new stent based on the superelasticity of the NiTi alloy for colon obstruction, which is the first clinical manifestation of colorectal cancer in up to 29% of cases. The stent is auto-expandable diamond cell type, manufactured from a NiTi tube with 4.5 mm in diameter, in which longitudinal grooves were performed by cutting laser technique. The expansion process to the final shape was made by deformation in the martensite state. The stent reaches a high free expansion rate of 7, with a longitudinal variable radial strength and a bell-shaped profile in the extremes in order to avoid migration. Finite elements models were used for simulating the mechanical behaviour. The prototype was evaluated by implantation in a colon stenosis model of 6 mm in diameter performed in a porcine speciment. The stent gave a good deployment, fixation and capability to open the gap up to 15 mm in diameter.