Elastomer Fixation to Rigid Substrates via Porous Attachment
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Solution Overview
Problem
Existing orthopedic devices, such as intervertebral disc prostheses, face challenges in securely attaching elastomeric members to rigid substrates, particularly in withstanding tensile forces and replicating natural motion and shock absorption, as conventional methods like adhesives and porous coatings are inadequate.
Innovation Solution
A porous attachment structure with a net porosity greater than 21.5% is integrated into the substrate, allowing an elastomeric body to impregnate and form a continuous bridge or layer, providing strong fixation by incorporating a lattice structure like perforated plates, trabecular metal, or wire mesh, which enhances the bond between the elastomeric member and the rigid substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesives or porous coatings are used to attach elastomeric members to rigid substrates, then the attachment method is simple, but the fixation strength is insufficient to withstand tensile forces
Solution Approach 1:
The patent applies porous materials by integrating a porous attachment structure (such as porous metal coatings or sintered metal layers) onto the rigid substrate surface. The elastomeric material impregnates these porous structures during molding, creating a mechanical interlock that significantly enhances fixation strength compared to smooth surfaces or simple adhesives. The porosity allows deep penetration and anchoring of the elastomer, resisting tensile forces effectively.
Solution Approach 2:
The patent employs composite materials by combining the rigid substrate with a porous attachment layer and the elastomeric material into an integrated composite structure. This multi-material composite approach creates synergistic effects where each material contributes its superior properties: the rigid substrate provides structural support, the porous layer provides mechanical interlocking, and the elastomer provides flexibility and shock absorption, collectively achieving high fixation strength.
2Strength
If mechanical interlocking undercuts or porous surfaces are used, then fixation strength improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-forming the porous attachment structure on the rigid substrate before the elastomeric material is applied. This porous structure is created in advance through processes like plasma spraying, sintering, or electrochemical deposition, allowing the elastomer to simply impregnate the pre-prepared pores during molding, thereby simplifying the overall manufacturing process while maintaining high fixation strength.
3Reliability
If the elastomeric member is firmly bonded to the rigid substrate, then shock absorption and natural motion replication improve, but the ability to withstand tensile forces may be compromised
Solution Approach 1:
The patent applies local quality by creating a gradient in the attachment structure, where the porous attachment structure provides strong mechanical interlocking at the interface to resist tensile forces, while the bulk elastomeric material maintains its inherent flexibility and shock-absorbing properties. This localized enhancement at the bonding interface allows the elastomer to remain soft and compliant in its functional regions while achieving strong attachment where needed.
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
This solution achieves a secure and stable attachment of elastomeric members to rigid substrates, significantly increasing fixation strength and resistance to deformation under load, thereby improving the performance of orthopedic devices like spinal disc prostheses by distributing stress and preventing disassociation.
Implementation Method 1
an elastomeric body having a portion adjacent to the portion of the substrate and impregnating the porous attachment structure
Data Source
AI summary
A surgical implant, especially an artificial intervertebral disc, includes a rigid substrate (513) having a porous attachment structure (512) that covers a portion of the substrate and an elastomeric body (510) that is fastened to the substrate by impregnating the porous attachment structure. The porous attachment structure has a net porosity greater than 21.5%. The porous attachment structure may be, for example, a perforated plate or a screen spaced from a substrate surface, or a layer of trabecular metal or an open-cellular material.