Spinal Interbody Device with Compliant Inner Dampener
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Solution Overview
Problem
Existing spinal interbody devices face issues with rigidity leading to subsidence and nerve agitation, or lack of compression resulting in migration and escape from the interbody space.
Innovation Solution
A spinal interbody device combining rigid and compressible components, using materials like PEEK, thermoplastic polyurethane elastomers, and mechanical springs to absorb axial loads while limiting subsidence and endplate erosion, with a design that includes top and bottom shells and an inner dampener for dynamic stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a solid sphere interbody device is used, then stabilization is achieved, but rigidity causes subsidence and nerve agitation
Solution Approach 1:
The device employs different material properties in different regions: the outer shell uses rigid material (PEEK, carbon fiber reinforced PEEK, or metal) for structural stability, while the inner core uses compressible material (hydrogel, elastomer, or foam) for load absorption. This local differentiation resolves the contradiction by providing rigidity where needed for stabilization and compressibility where needed to prevent subsidence.
Solution Approach 2:
The interbody device is constructed as a composite structure combining rigid and compressible materials. The outer shell may be made of rigid PEEK or metal while the inner core contains compressible hydrogel, elastomer, or foam materials. This composite construction allows the device to simultaneously provide structural support and compression absorption, preventing both subsidence and migration.
2Strength
If non-rigid hydrogel is used, then compression is absorbed, but migration and escape from interbody space occurs
Solution Approach 1:
The device assigns different functional zones: the inner core uses compressible materials (hydrogel, elastomer, foam) for absorption, while the outer shell uses rigid materials (PEEK, carbon fiber reinforced PEEK, or metal) for containment. This local quality differentiation allows compression absorption without migration, as the rigid shell constrains the compressible inner material within the interbody space.
Solution Approach 2:
The composite structure combines compressible inner materials (hydrogel, elastomer, foam) with rigid outer shell materials (PEEK, carbon fiber reinforced PEEK, or metal). This composite construction provides both compression absorption capability and retention reliability, preventing escape while maintaining the compression absorption function.
3Strength
If rigid material is used, then structural support is provided, but subsidence and endplate erosion occur
Solution Approach 1:
The device provides structural support through the rigid outer shell (PEEK, carbon fiber reinforced PEEK, or metal) while the compressible inner core (hydrogel, elastomer, or foam) absorbs axial loads. This local quality differentiation prevents subsidence and endplate erosion by distributing compressive forces through the compressible inner material rather than concentrating them on the endplates.
Solution Approach 2:
The composite structure uses rigid outer shell materials (PEEK, carbon fiber reinforced PEEK, or metal) for structural support and compressible inner core materials (hydrogel, elastomer, or foam) for load absorption. This composite construction provides structural support while preventing subsidence and endplate erosion through the compressible inner layer.
4Strength
If compressible material is used, then axial loads are absorbed, but device placement is not maintained
Solution Approach 1:
The device maintains placement through the rigid outer shell (PEEK, carbon fiber reinforced PEEK, or metal) while absorbing axial loads through the compressible inner core (hydrogel, elastomer, or foam). This local quality differentiation ensures that the compressible material absorbs loads without compromising placement stability, as the rigid shell provides structural containment.
Solution Approach 2:
The composite structure combines compressible inner core materials (hydrogel, elastomer, or foam) for axial load absorption with rigid outer shell materials (PEEK, carbon fiber reinforced PEEK, or metal) for placement maintenance. This composite construction achieves both load absorption and placement stability.
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 device effectively supports and absorbs spinal loads, reducing subsidence and migration, while maintaining placement and providing dynamic stabilization, with materials that restore shape and durability over time.
Implementation Method 1
compressible components include material of greater compressibility than material of rigid components
Implementation Method 2
inner dampener of second dampening material... thermoplastic polyurethane elastomers... restore shape and durability over time
Implementation Method 3
alternative embodiments, an inner dampener may comprise a mechanical spring and like compressible components
Implementation Method 4
inner dampener may comprise a mechanical spring
Data Source
AI summary
A spinal interbody device includes a compliant inner dampener in combination with outer shells. An inner dampener includes a rim with pillars and heads coupled to a complementary structure of the outer shells.