Hydrogel ACL Implant with Variable Stiffness
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Solution Overview
Problem
Current artificial ligaments for ACL replacement face issues such as mechanical failures, biocompatibility problems, and high complication rates, leading to poor long-term efficacy and safety concerns, with existing materials failing to replicate the mechanical properties of native ligaments and tendons effectively.
Innovation Solution
A biocompatible hydrogel-based device with a fibrous structure, comprising polyvinyl alcohol hydrogel fibers, designed to mimic the mechanical properties of native ligaments and tendons, featuring adjustable tensile strength and strain, and osseointegration-promoting substances for enhanced integration and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If non-biodegradable artificial ligaments are used, then structural integrity is maintained, but biocompatibility problems and immunogenic reactions occur
Solution Approach 1:
The patent changes the material parameter from non-biodegradable to biodegradable polymers, specifically using poly-L-lactic acid (PLLA) and polyglycolic acid (PGA) in controlled ratios. This parameter change allows the implant to maintain structural integrity during the critical healing period while gradually degrading to avoid long-term biocompatibility issues and immunogenic reactions.
Solution Approach 2:
The patent employs composite materials by combining biodegradable polymers (PLLA and PGA) in specific ratios within the braided structure. This composite approach allows optimization of both mechanical strength for structural support and controlled degradation rate for biocompatibility, resolving the contradiction between maintaining integrity and avoiding harmful immune responses.
2Object-affected harmful factors
If biodegradable scaffolds are used, then biocompatibility is improved, but control of scaffold degradation and mechanical properties remains difficult
Solution Approach 1:
The patent systematically varies the composition ratio of PLLA to PGA (e.g., 70:30, 50:50, 30:70) to precisely control both the degradation rate and mechanical properties. By changing these material parameters, the patent achieves predictable scaffold behavior that balances biocompatibility with controllable degradation, reducing the complexity of managing degradation control.
3Object-affected harmful factors
If autograft tissues are extracted, then biocompatibility is ensured, but donor-site morbidity and initial low strength occur
Solution Approach 1:
The patent creates a composite braided structure combining PLLA and PGA fibers that provides initial mechanical strength superior to autografts while maintaining biocompatibility. The interwoven architecture of the braided design distributes mechanical loads effectively, ensuring high initial strength without requiring tissue extraction from donor sites.
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 hydrogel device demonstrates improved biocompatibility, mechanical properties matching those of native ligaments, and enhanced integration with bone, reducing the risk of complications and improving the durability and safety of ACL replacement procedures.
Implementation Method 1
a biocompatible device in the form of an elongated body comprising a flexible median part between two end parts, said body having a fibrous structure formed from biocompatible hydrogel fibers
Data Source
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AI summary
The present invention relates to a hydrogel based device for use as tissue repair. The device comprises a median part between two end parts. The median and end parts have a different tensile stiffuess.