Biodegradable Magnesium Alloy Composition for Orthopedic Implants
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Solution Overview
Problem
Current orthopedic implants made from metallic, polymer, or ceramic materials face issues such as mismatch with bone, implant failure, low strength, deformation, or brittleness, necessitating a material with improved chemical inertness, strength, rigidity, biocompatibility, tissue receptivity, and corrosion resistance.
Innovation Solution
Development of a biodegradable Mg—Zn—X alloy, where X represents —Ca—Mn or —Dy—Sr, with specific weight percentages of Zn, Ca, Mn, Dy, and Sr, produced through a multilayer melting and atomization process without toxic flux materials, ensuring homogenization and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional metallic materials (stainless steel, titanium, chromium-cobalt alloys) are used for orthopedic implants, then strength and mechanical properties are improved, but biocompatibility and tissue receptivity deteriorate due to mismatch with bone, leading to implant loosening and failure
Solution Approach 1:
The patent changes the chemical composition parameters by using magnesium as the base metal and adding specific amounts of zinc (0.1-3.0 wt%), calcium (0.1-1.5 wt%), manganese (0.1-0.9 wt%), and either dysprosium (0.1-0.7 wt%) or strontium (0.1-0.9 wt%). This parameter optimization achieves both high strength and improved biocompatibility, resolving the contradiction between mechanical properties and tissue receptivity
Solution Approach 2:
The patent creates a composite alloy system Mg-Zn-Ca-Mn-Dy/Sr that combines the advantages of different elements: magnesium provides biocompatibility and biodegradability, zinc enhances strength and corrosion resistance, calcium promotes bone growth, manganese improves mechanical properties, and dysprosium or strontium further enhance biocompatibility. This composite approach simultaneously achieves strength and reliability
2Reliability
If polymers (polyethylene, polymethylmethacrylate) are used for orthopedic implants, then biocompatibility is improved, but strength and rigidity deteriorate, causing deformation and unsuitability for heavy load applications
Solution Approach 1:
The patent changes the material class from polymer to biodegradable metal alloy, optimizing the chemical composition to achieve both high strength (yield strength >100 MPa, tensile strength >150 MPa) and biocompatibility. The specific alloying elements and their controlled concentrations enable the material to withstand heavy loads while maintaining tissue receptivity
3Reliability
If ceramics (aluminum oxide, silicon oxide, zirconium oxide, calcium phosphate) are used for orthopedic implants, then chemical inertness and biocompatibility are improved, but mechanical properties deteriorate due to brittleness
Solution Approach 1:
The patent changes from ceramic materials to a metal alloy system, optimizing the composition to achieve both chemical inertness and high mechanical strength. The magnesium-based alloy with zinc, calcium, manganese, and dysprosium/strontium provides yield strength >100 MPa and tensile strength >150 MPa while maintaining chemical stability and biocompatibility suitable for orthopedic applications
4Reliability
If alloying elements are added to improve mechanical properties and biocompatibility, then material performance is improved, but cost increases
Solution Approach 1:
The patent uses partial additions of expensive alloying elements (zinc at 0.1-3.0 wt%, calcium at 0.1-1.5 wt%, manganese at 0.1-0.9 wt%, and dysprosium or strontium at 0.1-0.9 wt%) rather than high concentrations. This partial action approach achieves the required biocompatibility and mechanical properties while controlling material costs, making the alloy economically viable for orthopedic implants
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The alloy achieves zero cytotoxicity, low cost, and effective biocompatibility for orthopedic applications, with improved mechanical properties and corrosion resistance, suitable for temporary implants.
Implementation Method 1
melting the alloy components at about 700° C. to about 850° C.
Implementation Method 2
atomizing the melt of step (c) into millimeter size droplets using jets of inert gas
Data Source
AI summary
The present invention relates to a biodegradable alloy of Formula (I): Mg—Zn—X, wherein X represents —Ca—Mn or —Dy—Sr, wherein Zn is about 0.1 wt % to about 3.0 wt %, Dy is about 0.1 wt % to about 0.7 wt %, Sr is about 0.1 wt % to about 0.9 wt %, Ca is about 0.1 wt % to about 1.5 wt %, Mn is about 0.1 wt % to about 0.9 wt % and Mg is balance with impurities. The present invention further relates to a method for producing alloys, wherein the method comprises: (a) placing alloy components in a crucible, wherein the alloy components are placed in the crucible in a multilayer arrangement; (b) melting the alloy components at about 700° C. to about 850° C.; (c) stirring the melt of step (b) at about 400 rpm to about 500 rpm; (d) atomizing the melt of step (c) into millimeter size droplets using jets of inert gas; and (e) cooling and depositing the atomized alloy melt to obtain an ingot.