Biodegradable Magnesium Alloys for Innovative Stents

The main drawback of a conventional stenting procedure is the high risk of restenosis. The idea of a stent that "disappears" after having fulfilled its mission is very intriguing and fascinating, since it can be expected that the stent mass decreases in time to allow the gradual transmission of the mechanical load to the surrounding tissues owing to controlled dissolution by corrosion. Magnesium and its alloys are appealing materials to design biodegradable stents. The objective of this work is to develop, in a finite element framework, a model of Magnesium degradation able to predict the corrosion rate, thus providing a valuable tool to the design of bioresorbable stents. Continuum damage mechanics is suitable for modelling several damage mechanisms, including different types of corrosion. Comparisons with experimental tests show that the developed model can reproduce the behavior of different Magnesium alloys subjected to static corrosion tests. The study shows that the parameters identification for a correct calibration of the model response on the results of uniform and stress corrosion experimental tests is reachable. Moreover, 3D stenting procedures accounting for interaction with the arterial vessel are simulated. The modelling approach gives the possibility of accounting for the combined effects of aggressive environment and mechanical loading.