From Bench Testing to Virtual Implantation: A Comparative Study Between Poly-l-Lactic Acid and Nickel-Titanium Braided Stents

Bioresorbable braided stents represent a promising solution for the treatment of peripheral artery disease, providing temporary mechanical support before gradually degrading into biocompatible byproducts. Previous studies have highlighted their lower mechanical performance compared to permanent metallic stents. However, their implantation in lower limb arteries remains unexplored, leaving uncertainty on whether their mechanical performance is sufficient for effective treatment. The aim of the present study was to evaluate the performance of a poly-l-lactic acid (PLLA) braided stent for the treatment of lower limb arteries through in silico analysis and compare it with that of a nickel-titanium (NiTi) device. A finite element (FE) model of the PLLA stent was implemented and validated against experimental bench test data. Subsequently, the mechanical characteristics of the PLLA device were compared to those of a NiTi stent, with identical geometrical features, through FE simulations of two bench tests (i.e., parallel plate compression and crimping tests). Finally, a virtual implantation procedure of both devices in a patient-specific lower limb artery was conducted by FE analysis, accounting for three different arterial wall conditions, to compare the stents' treatment performance. The FE analysis of the bench tests confirmed that the PLLA stent generated much lower force magnitudes than the NiTi device. Moreover, the virtual implantation procedure indicated the limited short-term performance of the PLLA stent for the treatment of peripheral artery disease in terms of risk for permanent deformations, low lumen gain, high values of incomplete stent apposition and a nonuniform distribution of contact pressure on the arterial wall.