Prosthetic Intervertebral Discs with Compressible Core
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current artificial intervertebral discs, such as ball and socket or elastomer types, fail to replicate the natural disc's biomechanical functions effectively, leading to degeneration of adjacent discs due to uneven load distribution and lack of compressibility, and suffer from interface issues like polymeric debris generation and shear-fatigue failure.
Innovation Solution
Prosthetic intervertebral discs with upper and lower endplates separated by a compressible core member, where the endplates are held together by high tensile strength fibers or an engagement mechanism, and optionally include adjustable core structures and vertebral body fixation elements to mimic the natural disc's biomechanics and load-sharing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ball and socket type artificial discs are used to allow free rotation between vertebrae, then mobility is improved, but load sharing capability deteriorates and adjacent disc degeneration occurs
Solution Approach 1:
The patent changes the physical parameters of the artificial disc by incorporating a compressible core member with specific elastic modulus values (0.1-10 MPa for the core, 1-100 MPa for the endplates) to replicate the biomechanical properties of natural discs, enabling both mobility and load sharing
Solution Approach 2:
The patent uses composite material construction with different materials for the core member (elastomer, hydrogel, or foam) and endplates (metal, ceramic, or polymer), creating a multi-material system that provides both compressibility for load sharing and rotational freedom for mobility
2Strength
If elastomer type artificial discs are used to absorb shock and provide load bearing capability, then vertical direction shock absorption is improved, but interface bonding reliability deteriorates due to polymeric debris generation and shear-fatigue failure
Solution Approach 1:
The patent extracts the elastomer material from direct contact with metal plates, placing it only in the core member that does not interface with vertebral bodies, thereby eliminating the source of polymeric debris while maintaining shock absorption capability
Solution Approach 2:
The patent copies the functional properties of natural disc materials (annulus fibrosus and nucleus pulposus) using elastomer and hydrogel/foam materials in the core member, replicating the biomechanical behavior without using metal-polymer interfaces
3Strength
If artificial discs with metal plates and bearing surfaces are used to provide structural support, then stiffness is improved, but compressibility and instantaneous access of rotation deteriorate
Solution Approach 1:
The patent changes the material parameters by selecting endplate materials with elastic modulus of 1-100 MPa and core materials with 0.1-10 MPa, creating a gradient of stiffness that provides both structural support and compressibility
Solution Approach 2:
The patent introduces dynamic characteristics by making the core member compressible and the endplates flexible enough to allow instantaneous access of rotation, replicating the natural disc's ability to adapt to varying loads and motions
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 discs effectively distribute loads and maintain disc integrity by replicating the natural disc's biomechanics, reducing adjacent disc degeneration and providing long-term stability with improved bonding and wear resistance.
Implementation Method 1
a compressible core member disposed between the two endplates
Implementation Method 2
the elastic properties of the fibers...enable the prosthetic disc structure to mimic the functional characteristics and biomechanics of a normal-functioning, natural disc
Implementation Method 3
The two plates are held together by at least one fiber wound around at least one region of the top endplate and at least one region of the bottom endplate. The fibers are generally high tensile strength fibers with a high modulus of elasticity
Data Source
AI summary
Prosthetic intervertebral discs, systems including such prosthetic intervertebral discs, and methods for using the same are described. The subject prosthetic discs include upper and lower endplates separated by a compressible core member. The subject prosthetic discs exhibit stiffness in the vertical direction, torsional stiffness, bending stiffness in the saggital plane, and bending stiffness in the front plane, where the degree of these features can be controlled independently by adjusting the components, construction, and other features of the discs.