Bean-Shaped Multi-Layer Intervertebral Spacer
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Solution Overview
Problem
Current lumbar spinal pathologies treatments, such as arthrodesis and anterior disc prosthesis, face challenges including limited motion range, increased wear on neighboring discs, complex and risky installation procedures, precision difficulties, and inability to be installed via posterolateral access, which increases costs and risks of loosening and instability.
Innovation Solution
A multi-layer disc spacer with a bean-shaped design comprising a lower and upper titanium layer and an intermediate elastomeric layer, allowing for deformation and shock absorption, enabling posterolateral installation and accommodating anatomical movements without imposing specific kinematics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If arthrodesis with solid cages is used to treat lumbar spinal pathologies, then stability is improved, but the patient's range of motion is limited and neighboring discs wear out faster
Solution Approach 1:
The cage structure is transformed from a solid, rigid configuration to a modular system with adjustable parameters. The cage can be configured with different wall thicknesses, strut arrangements, and filling densities to provide variable stiffness, allowing it to maintain spinal stability while preserving physiological range of motion through controlled flexibility
Solution Approach 2:
The cage employs composite construction combining rigid structural elements (titanium alloy walls and struts) with flexible internal filling materials (bone graft or synthetic bone substitute). This composite structure provides both the stability needed for fusion and the controlled flexibility to maintain motion, resolving the contradiction between stability and range of motion
2Adaptability or versatility
If anterior disc prosthesis is implanted to restore disc movements, then range of motion is improved, but the installation procedure becomes complex and risky requiring aorta and vena cava mobilization
Solution Approach 1:
Instead of approaching the disc space from the anterior side as in traditional disc prostheses, this invention inverts the approach by accessing through the posterior or posterolateral route. This reversal of the surgical pathway eliminates the need to mobilize major blood vessels while still achieving disc space access and prosthesis implantation, thereby reducing surgical complexity and risk
3Adaptability or versatility
If two-part prosthesis with truncated spheres is used for posterior installation, then range of motion is restored, but precision difficulties occur during installation and stability is compromised
Solution Approach 1:
The prosthesis employs an asymmetric design where the upper and lower articulating surfaces have different geometries and orientations. This asymmetry creates a self-aligning mechanism that guides the components into proper alignment during implantation, eliminating the precision difficulties associated with symmetric truncated sphere designs and ensuring stable, reproducible positioning
4Ease of operation
If cylindrical prosthesis is implanted by posterior route, then installation is simplified, but stability is questionable and loosening may occur over time
Solution Approach 1:
The prosthesis utilizes spherical or spheroidal articulating surfaces instead of cylindrical geometry. This curvature provides congruent contact between articulating surfaces, distributing loads more evenly and preventing the instability and loosening problems associated with cylindrical designs, while maintaining ease of installation through the posterior approach
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 multi-layer disc spacer provides stability, tolerates positioning inaccuracies, allows for natural anatomical movements, and enhances shock absorption, reducing the risks associated with traditional methods while facilitating safer and more cost-effective posterolateral installation.
Implementation Method 1
allows shock absorption
Implementation Method 2
allowing for deformation and shock absorption
Implementation Method 3
intermediate layer being made in material different from that of the lower and upper layers and less rigid
Data Source
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AI summary
A multi-layer intervertebral spacer (1) comprises at least three superimposed layers, i.e. lower (3), top (2) and at least one intermediate (4) layers, wherein said at least one intermediate layer (4) is made of a material which differs from the material of the lower (3) and top (2) layers and is less rigid and the inventive spacer, in a view from bellow, is generally shaper in the form of a bean and can be placed by means of a posterior or pasterolateral surgery.