Iron-Polymer Composite for Load-Bearing Absorbable Implants
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Solution Overview
Problem
Current absorbable implantable medical devices for internal fixation, such as those made from polymers and magnesium-based alloys, lack the mechanical strength and durability needed for load-bearing applications due to limitations in bending and tensile strength, and generate insoluble corrosion products that can cause long-term biological burdens.
Innovation Solution
An iron-based alloy absorbable and implantable medical device is developed, combining an iron-based alloy with a degradable polymer, where the mass ratio of the alloy to polymer is between 1:4 and 4:1, and includes antioxidants and complexing agents to reduce the amount of insoluble corrosion products by accelerating corrosion and promoting the formation of soluble iron complexes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If absorbable polymer materials are used for internal fixation devices, then biocompatibility is improved, but mechanical strength is insufficient for load-bearing applications
Solution Approach 1:
The invention uses composite materials consisting of iron-based alloy particles dispersed in a degradable polymer matrix. The iron-based alloy provides high mechanical strength and load-bearing capacity, while the degradable polymer matrix ensures biocompatibility and gradual degradation. This composite structure allows the device to function as permanent metal during the healing period and then degrade safely over time.
2Strength
If permanent metal materials are used for internal fixation devices, then mechanical strength is improved, but long-term biological risk increases
Solution Approach 1:
The invention changes the temporal parameters of material properties by using a composite where the metal phase provides initial strength and the polymer phase degrades over time. The device transitions from a permanent metal structure to a gradually degrading composite, ultimately becoming fully absorbable. This parameter change in degradation timing eliminates long-term biological risks while maintaining necessary mechanical strength during the critical healing period.
3Strength
If magnesium-based alloy is used for internal fixation devices, then mechanical strength is improved compared to polymer, but corrosion rate is too high causing early loss of fixing effect
Solution Approach 1:
The invention applies local quality control by dispersing iron-based alloy particles throughout the polymer matrix rather than using bulk magnesium alloy. The iron-based alloy particles provide localized high-strength reinforcement where needed, while the polymer matrix controls the overall degradation rate. This local reinforcement approach achieves the necessary mechanical strength without the excessive corrosion rate problem of magnesium-based alloys.
4Strength
If iron-based alloy is used to achieve high mechanical strength, then mechanical properties are improved, but amount of insoluble corrosion products increases
Solution Approach 1:
The invention extracts only the necessary amount of iron-based alloy from the overall device structure, using it as dispersed particles within the degradable polymer matrix rather than as the bulk material. This extraction approach provides sufficient mechanical strength through reinforcement while minimizing the total amount of metal present, thereby reducing the quantity of insoluble corrosion products generated during degradation.
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 device achieves high initial mechanical properties comparable to permanent metals while minimizing the burden of insoluble corrosion products on tissues, ensuring effective and safe internal fixation for load-bearing applications.
Implementation Method 1
a degradable polymer... degradation of the polymer will generate an acidic environment
Implementation Method 2
promoting the formation of soluble iron complexes
Implementation Method 3
corrosion of the iron-based alloy may be obviously accelerated... corrosion products generated by oxygen absorption corrosion
Data Source
AI summary
An iron-based alloy absorbable and implantable medical device for internal fixation. A substrate includes an iron-based alloy and degradable polymer. The mass ratio of the iron-based alloy to the degradable polymer is between 1:4 and 4:1. The weight-average molecular weight of the degradable polymer is between 150000 to 3000000, and the polydispersity index thereof is between 1 and 6. The device further includes antioxidants. The iron-based alloy is used as a load-bearing framework or reinforcement phase of the device. By adjusting the mass ratio of the iron-based alloy to the degradable polymer and the combination mode thereof, the corrosion rate of the iron-based alloy in the late period of the implantation is accelerated, and the quantity of corrosion products poorly soluble in the iron-based alloy is reduced. Adding antioxidants to the device further reduces the quantity of the corrosion products poorly soluble in the iron-based alloy.