Gradient Polymer Alloy Orthopedic Implants
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Solution Overview
Problem
Current joint replacement implants made from metal, ceramic, and UHMWPE materials cause adverse tissue responses and have limitations in strength, lubricity, and wear-resistance, leading to complications such as bone resorption, inflammation, and the need for revision surgeries.
Innovation Solution
Development of interpenetrating polymer networks (IPNs) and semi-IPNs using hydrophobic thermoset or thermoplastic polymers combined with ionic polymers to create orthopedic implants with enhanced mechanical strength, lubricity, and wear-resistance, along with a compositional gradient for improved properties like high water content and biocompatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal, ceramic, and UHMWPE materials are used for joint replacement implants, then mechanical strength and durability are improved, but adverse tissue responses such as bone resorption, inflammation, and wear particles are generated
Solution Approach 1:
The patent applies composite materials by combining hydrophobic thermoset or thermoplastic polymers with ionic polymers to create interpenetrating polymer networks (IPNs) and semi-IPNs. This composite structure integrates the mechanical strength of hydrophobic polymers with the biocompatibility and lubricity of ionic polymers, resolving the contradiction between strength and adverse tissue responses.
Solution Approach 2:
The patent applies local quality by creating compositional gradients within the implant material. The gradient transitions from regions with higher ionic polymer content (providing biocompatibility and lubricity) to regions with higher hydrophobic polymer content (providing mechanical strength), allowing different properties to be localized to different regions of the implant.
2Reliability
If traditional polymer materials are used for joint implants, then biocompatibility is improved, but mechanical strength and wear-resistance are insufficient
Solution Approach 1:
The patent combines traditional ionic polymers (providing biocompatibility) with hydrophobic thermoset or thermoplastic polymers (providing mechanical strength) to create IPNs and semi-IPNs. This composite approach allows both biocompatibility and mechanical strength to be achieved simultaneously, resolving the contradiction between these properties.
3Strength
If hydrophobic thermoset or thermoplastic polymers are used alone, then mechanical strength is improved, but lubricity and water content are insufficient
Solution Approach 1:
The patent creates composite IPN and semi-IPN structures where hydrophobic polymers (providing strength) are interpenetrated with ionic polymer networks (providing lubricity and water content). The ionic polymer phase provides hydrophilic channels that enable water absorption and lubrication, while the hydrophobic polymer matrix maintains mechanical integrity.
Solution Approach 2:
The patent applies local quality by creating compositional gradients where regions with higher ionic polymer content provide lubricity and water content, while regions with higher hydrophobic polymer content provide mechanical strength. This spatial distribution of properties resolves the contradiction between strength and lubricity.
4Ease of manufacture
If uniform composition is used throughout the implant, then manufacturing is simplified, but performance optimization is limited
Solution Approach 1:
The patent applies local quality by implementing compositional gradients within the implant structure. The gradient allows different regions to have optimized compositions for their specific functions (e.g., higher ionic polymer content at articulating surfaces for lubricity, higher hydrophobic polymer content in structural regions for strength), while still using a single continuous manufacturing process.
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 IPN and semi-IPN compositions achieve high tensile and compressive strength, low friction, high water content, and biostability, reducing adverse tissue responses and the need for revision surgeries by mimicking natural joint properties.
Implementation Method 1
an ionic polymer second network configured to exhibit a compositional gradient between the bearing surface and the attachment zone
Implementation Method 2
ionic polymers to create orthopedic implants with enhanced mechanical strength, lubricity, and wear-resistance, along with a compositional gradient for improved properties like high water content
Implementation Method 3
IPN and semi-IPN compositions achieve high tensile and compressive strength, low friction, high water content, and biostability
Data Source
AI summary
Orthopedic implants having a bone interface member and a water swellable IPN or semi-IPN with a stiffness, hydration, and/or composition gradient from one side to the other and physically attached to the bone interface member. The invention also includes an orthopedic implant system including an implant that may conform to a bone surface and a joint capsule. The invention also includes orthopedic implants with water swellable IPN or semi-IPNs including a hydrophobic thermoset or thermoplastic polymer first network and an ionic polymer second network, joint capsules, labral components, and bone interface members. The invention also includes a method of inserting an orthopedic implant having a metal portion and a flexible polymer portion into a joint, including inserting the implant in a joint in a first shape and changing the implant from a first shape to a second shape to conform to a shape of a bone.