Surface Textured Implants Managing Coating Flaking
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Solution Overview
Problem
Drug-eluting stents face issues with coating flaking and embolization due to radial stresses during expansion, leading to clinical complications like blood clots and flow interruption, as increasing adhesion alone does not fully address the problem of flaking and dislodgement.
Innovation Solution
A radially expandable device with surface texture features that control the size, shape, and quantity of coating fragments, incorporating peaks, valleys, and plateaus to manage stress fractures and coating detachment, ensuring fragments are too small to cause thrombi or emboli.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adhesion of the coating to the implant surface is increased to minimize flaking, then coating retention is improved, but coating fragments still crack and flake off during structural deformation causing embolism and blood clots
Solution Approach 1:
The invention changes the physical state of the coating material from rigid/semi-rigid to elastomeric, which can undergo reversible deformation. This parameter change in material flexibility allows the coating to stretch and deform with the implant during expansion and compression cycles without cracking, thereby preventing flaking and embolism while maintaining strong adhesion to the surface
Solution Approach 2:
The invention uses composite material structures including an elastomeric coating layer that can deform reversibly, and may include additional layers such as a radiopaque layer with contrasting density. The composite structure combines the adhesion benefits of surface texturing with the deformation resistance of elastomeric materials, preventing coating failure during structural changes
2Strength
If rigid and semi-rigid coatings are used on the implant, then coating strength is improved, but the coatings inevitably crack and flake off during structural deformation
Solution Approach 1:
The invention changes the mechanical properties parameter of the coating from rigid/semi-rigid to elastomeric. This parameter change enables the coating to maintain strength while gaining the ability to deform reversibly, preventing crack formation and maintaining compositional stability during structural deformation of the implant
Solution Approach 2:
The elastomeric coating is designed to be a sacrificial layer that can deform and eventually degrade or detach in a controlled manner, replacing the need for permanently rigid coatings. This approach accepts temporary coating material consumption to prevent harmful flaking and embolism
3Quantity of substance
If the surface area of the implant is increased to enhance drug delivery, then therapeutic effect is improved, but coating fragment production increases
Solution Approach 1:
The invention changes the coating material parameter to elastomeric, which prevents crack formation during deformation. This allows the implant to have increased surface area for enhanced drug delivery without the penalty of increased coating fragment production, as the flexible coating can accommodate surface irregularities and deformation without flaking
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
Devices and methods for controlling the flaking of coating fragments from medical implants and improving the delivery of therapeutic agents from such coatings are described.