Fibrous Prosthetic Disc for Load Distribution
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Solution Overview
Problem
Existing artificial intervertebral disc replacements, such as ball and socket type and elastic rubber type, fail to replicate the natural disc's mechanical properties, leading to degeneration of adjacent discs due to uneven load distribution and material fatigue.
Innovation Solution
A prosthetic intervertebral disc design featuring top and bottom endplates separated by a fibrous compressible element with an annular and nuclear region, held together by fibers, which can include integrated or separate vertebral body fixation elements, mimicking the mechanical properties of natural discs and addressing material fatigue issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ball and socket type artificial discs are used to restore normal kinematics, then free rotation between vertebrae is achieved, but vertical stiffness is excessively high and load sharing capability is lost
Solution Approach 1:
The patent changes the material parameters of the core element from rigid polyethylene to compliant elastomeric polymer, and modifies the structural parameters of the metal plates from smooth flat surfaces to rough porous surfaces with compliance features. This allows the disc to maintain vertical compliance while preserving rotational capability.
Solution Approach 2:
The patent uses a composite structure combining metal plates with elastomeric polymer core. The metal plates provide structural support and bone ingrowth capability, while the elastomeric polymer provides vertical compliance and shock absorption, creating a composite material system that balances both rotational freedom and vertical stiffness requirements.
2Strength
If elastic rubber type artificial discs are used to absorb shock and bear load, then vertical compliance is improved, but material fatigue and debris generation occur after long term usage
Solution Approach 1:
The patent replaces the single elastomeric polymer material with a composite structure where the polymer is contained within a metal plate cage. This composite design allows the elastomeric polymer to provide shock absorption and load bearing, while the metal plate structure provides durability and prevents material fatigue failure, eliminating the debris generation problem.
Solution Approach 2:
The patent segments the artificial disc into distinct functional components: metal plate structures for structural support and durability, and elastomeric polymer for shock absorption. This segmentation allows each material to perform its optimal function while avoiding the weaknesses of using a single material for all functions.
3Strength
If interface surfaces of metal plates are made rough and porous to improve bonding with elastomer, then bonding strength is increased, but polymeric debris is generated after long term usage
Solution Approach 1:
The patent extracts the elastomeric polymer from direct contact with the rough porous metal plate interface by enclosing it within a metal plate cage structure. This eliminates the friction and wear at the interface that caused polymeric debris generation, while maintaining bonding strength through the containment structure.
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 prosthetic disc effectively distributes loads and maintains mechanical integrity, reducing the risk of adjacent disc degeneration and facilitating easy surgical implantation and removal, while preventing material fatigue and debris generation.
Implementation Method 1
a fibrous compressible element which has been impregnated with a polymeric component
Implementation Method 2
at least one fiber winds around at least one region of the top endplate and at least one region of the bottom endplate
Data Source
AI summary
A prosthetic intervertebral disc and methods for using the same are provided. The subject prosthetic discs are characterized by including top and bottom endplates separated by a fibrous compressible element that includes an annular region and a nuclear region. The two plates are held together at least one fiber wound around at least one region of the top endplate and at least one region of the bottom endplate. The subject discs may be employed with separate vertebral body fixation elements, or they may include integrated vertebral body fixation elements. Also provided are kits and systems that include the subject prosthetic discs.