Magnesium alloy and resorbable stents containing the same
Inventors
Stekker, Michael • Hort, Norbert • Feyerabend, Frank
Assignees
MEKO LASERSTRAHL-MATERIALBEARBEITUNGEN EK • Helmholtz Zentrum Hereon GmbH
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Publication Number
US-9566367-B2
Publication Date
2017-02-14
Expiration Date
Abstract
The present invention is directed to a magnesium alloy containing 5.0% by wt.-25.5% by wt. dysprosium, 0.01% by wt.-5.0% by wt. neodymium and/or europium, 0.1% by wt. 3.0% by wt. zinc, 0.1% by wt.-2.0% by wt. Zirconium, and balance to 100.0% by wt. magnesium, being degradable under physiological conditions and which is particularly suitable for the production of absorbable stents and to stents made thereof.
Core Innovation
The invention provides an absorbable stent made from a magnesium alloy. The magnesium alloy consists of dysprosium and neodymium and/or europium, together with zinc and zirconium, within specified weight percentage ranges based on the total weight of the alloy. The alloy further includes impurities within a defined ppm to weight percentage range, with the remainder being magnesium.
The invention defines compositional constraints that limit the total content of terbium, holmium, erbium, thulium, ytterbium, and lutetium to not more than 0.1% per wt. The magnesium alloy contains no yttrium and no gadolinium, and this absence is presented as a defined part of the absorbable stent alloy definition.
The disclosed stent is described in the context of degradation and performance requirements. The magnesium-alloy stent composition is characterized as enabling delayed/controlled corrosion kinetics while providing mechanical properties suitable for stent deformation, and it is discussed in comparison to prior Mg-Y and Mg-Gd systems. The document further indicates that imaging findings show the stents are not radio-opaque, and animal-study outcomes report successful stent behavior during and after deployment, including early re-endothelialization and in-stent restenosis comparable to reference stents.
Claims Coverage
The patent content provided includes one independent claim that defines the magnesium-alloy composition of an absorbable stent, including multiple quantitative constraints and compositional exclusions, and dependent claims that further narrow sub-ranges and specify intended anatomical applications. The inventive features are therefore centered on the alloy composition definition and on additional narrowing of zinc and zirconium ranges and application scope.
Magnesium alloy composition for an absorbable stent
An absorbable stent consisting of a magnesium alloy with dysprosium; neodymium and/or europium; zinc; zirconium; impurities; and balance magnesium, with specified weight percentage ranges for each component and an overall impurities limit.
Rare-earth element content limit and exclusion of yttrium and gadolinium
The alloy contains in total not more than 0.1% per wt. of terbium, holmium, erbium, thulium, ytterbium and lutetium, and contains no yttrium and no gadolinium.
Zinc range refinement
The absorbable stent is defined with zinc in a range of 0.1 wt.-2.0 wt.%.
Zirconium range refinement
The absorbable stent is defined with zirconium in a range of 0.1 wt.-0.3 wt.%.
Stent application to specified body systems
The absorbable stent is intended for implantation in blood vessels, urinary tracts, respiratory tracts, biliary tracts, or the digestive tract.
Overall, the claim coverage centers on a tightly defined magnesium-alloy composition for an absorbable stent, including the Dy plus Nd and/or Eu, Zn, and Zr ranges, with an explicit rare-earth total limit and explicit exclusion of yttrium and gadolinium. Dependent claims further narrow the zinc and zirconium ranges and limit the intended anatomical application to specified tracts.
Stated Advantages
Delayed/controlled corrosion kinetics.
Mechanical properties suitable for stent deformation.
Stents are not radio-opaque.
Early re-endothelialization.
In-stent restenosis comparable to reference stents in the reported animal study context.
Documented Applications
Absorbable stent implantation in blood vessels.
Absorbable stent implantation in urinary tracts.
Absorbable stent implantation in respiratory tracts.
Absorbable stent implantation in biliary tracts.
Absorbable stent implantation in the digestive tract.
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