Mechanical compliance and anti-migration performance of auxetic tracheal stents with multi-circular cores

Tracheal diseases such as tracheal stenosis and tracheomalacia often have a significant impact on patients' respiratory function. Traditional tracheal stents face issues such as displacement, granulation tissue hyperplasia, and axial foreshortening during clinical use, which limit their long-term efficacy. The mechanical behavior of auxetic tracheal stents was studied, focusing on the impact of design parameters on stent performance. Finite element analysis was used to assess the effects of different unit cell strut geometries (including connecting strut shape and unit cell core design) on the stent's stress-strain behavior, expansion performance, and anti-migration properties. The results show that the curved design stent exhibits a nonlinear stress-strain relationship similar to that of the trachea. The multi-circular core design demonstrated the best overall performance, with a radial recoil rate of 6.6% and a maximum anti-migration force of 641 N, representing a 51% improvement over the straight-bar stent. The multi-circular design significantly reduces the risk of granulation tissue formation through uniform stress distribution (maximum principal stress of 136 MPa) and low tracheal wall stress (0.24 MPa), making it a promising candidate for long-term implantation. This study provides theoretical support for the optimization of tracheal stent designs and lays the foundation for the long-term implantation of auxetic tracheal stents in the future.