Magnesium stents are a promising candidate in the emerging field of absorbable metallic stents (AMSs). In this study, the mechanical and corrosion performance of dog-bone specimens and a specific stent design of a magnesium alloy, WE43, are assessed experimentally in terms of their corrosion behaviour and mechanical integrity. It is shown that plastic strains that are induced in the struts of the stent during stent deployment have a critical influence in directing subsequent corrosion behaviour within the material. In addition, the deployment and scaffolding characteristics of the magnesium stent are elucidated and contrasted with those of a commercial stainless steel stent. The magnesium stent is found to support higher levels of cyclic strain amplitude than the stainless steel stent, even prior to degradation, and this may play a role in reducing in-stent restenosis. This study provides new insights into the experimental performance of a current AMS design and material whilst demonstrating the critical influence of plastic strain on the corrosion performance and scaffolding ability of an AMS.

No abstract

No abstract

Bioabsorbable magnesium (Mg) alloys have several advantages in biomedical implant applications as they reduce certain risks associated with conventional permanent implants. However, limited information is available for WE43 Mg alloy specimens with comparable size to that of biomedical implants such as cardiovascular stents and orthopaedic wires. The present work examines the corrosion and biological properties of WE43 stent precursor tubes and wire specimens suited for orthopaedic implants. The corrosion-induced loss of mechanical integrity as well as the corrosion-induced changes in surface morphology of the specimens are elucidated and compared. Cell viability assays were performed with human umbilical vein endothelial cells (HUVECs). It was observed that Mg ions released from the WE43 alloy acted as a growth stimulator of HUVECs.

In this study, the effect of fluid flow rate, surface roughness and strain level on the corrosion behavior of magnesium alloy AZ31 was characterized in a custom test bench. Specimens were prepared by mechanical polishing and subject to flow in a simulated body fluid at 37°C for 24 hrs. Compared to a specimen pre-strain of 0%, mass loss was shown to increase by approximately 6% with a specimen pre-strain of 10%. Similarly, mass loss increased by approximately 13% when the fluid flow rate was increased from 250ml/min to 500ml/min. Surface roughness had a significant influence on corrosion behavior. Compared to a specimen polished with a 1 µm diamond paste, the mass loss for a specimen polished with #600 sandpaper was 28% greater.