Comparative bending behaviors between fully covered and bare biodegradable polydioxanone biliary stents using a numerical approach

Abstract

A comparison of bending flexibility between bare biodegradable polydioxanone biliary stents (BBPBSs) and fully covered biodegradable polydioxanone biliary stents (FCBPBSs) developed for humans is presented in this study. Firstly, a series of BBPBSs and FCBPBSs were prepared by braiding method in order to investigate the relationship between the bending load and structure parameters (monofilament diameter and braid-pin number) through a three-point bending method. In addition, a series of three-point bending models based on actual stent specimens above was established and the bending flexibility of BBPBSs and FCBPBSs in three-point bending models was evaluated by the finite element method (FEM). Results showed that the simulation was in good agreement with the experiment, indicating that the simulation results could be used as the reference to access the mechanical behaviors of BBPBSs and FCBPBSs. Furthermore, the distinction in bending flexibility between BBPBSs and FCBPBSs was compared in this simulation and demonstrated that the existence of a nanomembrane component (NMP) in FCBPBS causes remarkable performance variation including bending load (all FCBPBSs increased by at least 0.65%), stress, plastic strain and energy conversion of the stent (the plastic dissipation energy of all FCBPBSs increased by at least 2.33J) in the bending process.