Biodegradable Magnesium Alloy Composition for Controlled Implant Degradation
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Solution Overview
Problem
Current metallic implant devices used in orthopedic, craniofacial, and cardiovascular applications do not degrade over time, leading to complications such as rejection by the body, stress-shielding effects, and the need for additional surgeries for removal, while existing biodegradable materials lack adequate mechanical strength and biocompatibility.
Innovation Solution
Development of biodegradable metal alloys comprising specific amounts of yttrium, calcium, zirconium, zinc, and magnesium, with optional strontium or cerium, to achieve controlled corrosion resistance and biocompatibility, minimizing hydrogen gas evolution and ensuring complete degradation within a medical timeframe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If permanent metallic implant devices (stainless steel, Co-Cr, titanium alloys) are used, then mechanical strength and stiffness are improved, but the implant does not degrade over time requiring additional surgery for removal
Solution Approach 1:
The patent changes the chemical composition parameters of metallic implants by incorporating biodegradable elements (Mg, Zn, Ca, Sr, Ce, Zr) in specific ratios. This transforms the material from permanent to biodegradable while maintaining mechanical properties through controlled alloying, allowing the implant to degrade at appropriate rates after serving its mechanical function.
Solution Approach 2:
The invention creates composite metallic alloys combining traditionally permanent metals (Ti, stainless steel, Co-Cr) with biodegradable metals (Mg, Zn, Ca, Sr, Ce, Zr). This composite approach allows the implant to exhibit both initial high mechanical strength and subsequent biodegradation capability, eliminating the need for removal surgery.
2Duration of action of stationary object
If biodegradable materials are used, then the implant degrades over time avoiding removal surgery, but mechanical strength and biocompatibility are insufficient
Solution Approach 1:
The patent modifies the composition parameters of biodegradable materials by adding specific amounts of strengthening elements (Zn: 1-10%, Ca: 0.1-5%, Sr: 0.1-3%, Ce: 0.1-3%, Zr: 0.1-5%) to pure magnesium or magnesium-based alloys. This enhances mechanical strength while preserving biodegradability, making the material suitable for load-bearing applications.
Solution Approach 2:
The invention develops composite biodegradable alloys where magnesium serves as the base metal providing biodegradability, while added elements (Zn, Ca, Sr, Ce, Zr) provide mechanical strengthening and improved biocompatibility. This composite structure achieves both adequate mechanical strength and controlled biodegradation.
3Strength
If high strength metallic alloys are used, then mechanical support is adequate, but stress-shielding effects occur reducing bone loading and stimulation
Solution Approach 1:
The patent introduces dynamic properties to the implant by making it biodegradable. The implant provides high mechanical strength initially to support bone healing, then gradually degrades over time, transferring load to the healing bone. This dynamic behavior eliminates stress-shielding effects that occur with permanent rigid implants.
Solution Approach 2:
The invention changes the temporal parameters of mechanical properties by controlling the degradation rate of the alloy. The implant maintains adequate strength during the critical healing period, then progressively reduces its mechanical properties as bone regenerates, ensuring continuous bone stimulation without stress-shielding.
4Strength
If current metallic biomaterials are used, then load-bearing capacity is sufficient, but toxic metallic ions and particles are released causing immune response and hypersensitivity
Solution Approach 1:
The patent changes the chemical composition parameters by replacing toxic elements (Ni, Cr, Co from stainless steel and Co-Cr alloys) with biocompatible biodegradable elements (Mg, Zn, Ca, Sr, Ce, Zr). This transformation maintains load-bearing capacity while eliminating toxic ion release, as these elements either form protective oxides or degrade into biocompatible ions.
Solution Approach 2:
The invention creates composite alloys using biocompatible base metals (Mg, Ti, stainless steel, Co-Cr) combined with biodegradable strengthening elements (Zn, Ca, Sr, Ce, Zr). This composite approach reduces toxic ion release by limiting the content of traditional alloying elements while maintaining mechanical properties through the biodegradable additives.
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 alloys provide adequate mechanical support during bone healing, degrade harmlessly, and avoid complications by maintaining biocompatibility and controlled corrosion, reducing the need for surgical removal.
Implementation Method 1
The alloy will degrade in a physiological environment such that it will not remain in the body when there is no longer a medical need for it
Data Source
AI summary
The invention relates to biodegradable, metal alloys, methods for their preparation and applications for their use. The alloys include magnesium and other components, such as, yttrium, calcium, zirconium, and zinc. These elements are alloyed together in specific combinations and amounts in order to achieve an alloy having desired properties and characteristics. In certain embodiments, strontium or cerium may be included as an additive. The resulting alloys are particularly suitable for forming various medical devices for implantation into the body of a patient.