Design and mechanical properties testing of a new cross-helical popliteal artery stent

The popliteal artery has complex deformations such as axial shortening, bending, squeezing and twisting, as well as specific positions across the knee joint. Up to now there is a high incidence of in-stent restenosis (ISR) after the stent treatment of the popliteal artery. This paper aimed to design a new type of popliteal artery stent -- cross-helical stent.to meet its deformation characteristics. The finite element analysis (FEA) method was used to test the mechanical properties of six stents with different winding height ratios of axial shortening, bending, plate extrusion, and torsional deformation. The results showed that the stents performance was affected by the ratio of winding height, the larger the winding height ratio, the worse the compliance, the worse the axial compressibility, but the better the radial support. And when the stent is torsional, the greater the winding height ratio is, the greater the stress is. In additon, the maximum stress was also related to the direction of torsion deformation, and the stress when the helix has the same direction with the torsion direction of the stent are was greater than that when the helix direction and torsion direction are opposite. Moreover, when the winding height ratio is 3:5, the performance of the stent is better, not only has better flexibility, its radial force, axial compression, and torsional deformation are better. It is concluded that the new cross-helical stent can adapt to the special deformation of popliteal artery and has good mechanical properties.