Biodegradable Magnesium-Calcium Alloy Implants with Adjustable Degradation
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Solution Overview
Problem
Current orthopedic implants made of non-degradable metals cause stress shielding, leading to bone remodeling, pain, and increased need for secondary surgeries, while biodegradable polymer devices lack mechanical strength and have unpredictable degradation rates, which can result in misaligned bone healing or prolonged implantation.
Innovation Solution
Development of biodegradable medical devices using magnesium-calcium alloys with adjustable properties such as degradation rate, residual stress, and surface integrity through hybrid dry cutting/hydrostatic burnishing or laser shock peening, allowing for tailored mechanical strength and degradation matching the bone healing rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If non-degradable metallic implants (titanium, stainless steel, cobalt-chromium alloys) are used, then mechanical strength and durability are improved, but stress shielding and bone remodeling occur leading to pain and secondary surgeries
Solution Approach 1:
The patent changes the material parameters by using biodegradable metals (magnesium, zinc, iron-based alloys) instead of non-degradable metals, and by controlling degradation rates through alloy composition and surface treatment parameters to match bone healing rates, thereby eliminating stress shielding while maintaining mechanical strength
Solution Approach 2:
The patent employs composite material strategies by creating biodegradable metal alloys combining multiple elements (e.g., magnesium-calcium-phosphorus, zinc-magnesium-aluminum) to achieve both mechanical strength and controlled biodegradability, resolving the contradiction between durability and stress shielding
2Object-generated harmful factors
If biodegradable polymer devices are used, then stress shielding is reduced, but mechanical strength is insufficient and degradation rates are unpredictable
Solution Approach 1:
The patent transitions from polymer to metal-based biodegradable materials, fundamentally changing the material parameter of mechanical strength while controlling degradation through alloy composition and surface treatment to achieve both high strength and predictable degradation
Solution Approach 2:
The patent utilizes porous surface structures and coatings on biodegradable metals to enhance mechanical interlocking with bone while controlling degradation rates, achieving both sufficient mechanical strength and predictable biodegradability
3Productivity
If biodegradable medical devices with fast degradation rates are used, then secondary surgeries are reduced, but bone alignment and healing may be compromised
Solution Approach 1:
The patent employs surface treatment parameters (anodization, plasma electrolytic oxidation, chemical conversion coatings) to control the degradation rate of biodegradable metals, matching it to bone healing rates to ensure both timely removal and reliable bone healing
Solution Approach 2:
The patent applies surface treatments and coatings before implantation to pre-establish controlled degradation characteristics, ensuring that the device degrades at the optimal rate for bone healing without compromising bone alignment or requiring secondary surgeries
4Reliability
If biodegradable medical devices with slow degradation rates are used, then bone alignment and healing are maintained, but stress shielding and prolonged implantation occur
Solution Approach 1:
The patent utilizes alloy composition parameters and surface treatment parameters to precisely control degradation rates, ensuring devices degrade completely within the bone healing period (typically 6-24 months) to eliminate stress shielding while maintaining bone healing reliability
Solution Approach 2:
The patent incorporates degradation monitoring through surface treatment design that responds to physiological conditions (pH, enzymes), creating a feedback mechanism where degradation accelerates as bone healing progresses, ensuring complete device removal by the time healing is complete
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 biodegradable medical devices provide appropriate stiffness and mechanical strength, reducing the need for secondary surgeries and stress shielding, while ensuring proper bone alignment and healing by adjusting degradation rates to match the healing process, thus minimizing adverse effects.
Implementation Method 1
hybrid dry cutting/hydrostatic burnishing
Implementation Method 2
surface treatment (e.g., hybrid dry cutting/hydrostatic burnishing or laser shock peening)
Implementation Method 3
laser shock peening
Implementation Method 4
Through degradation and wear, cracks can easily initiate
Implementation Method 5
biodegradable material having an adjustable rate of degradation
Data Source
AI summary
Disclosed herein are biodegradable medical devices comprising biodegradable materials (e.g., magnesium-calcium alloys) having an adjustable rate of degradation that can be used in various applications including, but not limited to, drug delivery applications, cardiovascular applications, and orthopedic applications to make biodegradable and biocompatible devices. Also disclosed herein are methods of making biodegradable medical devices comprising biodegradable materials by using, for instance, hybrid dry cutting/hydrostatic burnishing.