Knitted Endoprosthesis with Shifting Anti-Migration Loops
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Solution Overview
Problem
Current medical stents face challenges in maintaining flexibility while providing sufficient radial force to open body lumens without obstructing branch lumens, particularly in anatomies like the biliary tree, where they can block fluid flow or drainage.
Innovation Solution
An endoprosthesis with an elongated tubular member featuring knitted loops and intermediate rungs, including windows and anti-migration loops that shift radially outward to accommodate branch lumens, allowing for expanded access and drainage without compromising anchoring or migration prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a stent is designed with sufficient radial force to open the body lumen, then the stent can maintain lumen patency and anchor securely, but it may obstruct branch lumens and block fluid flow
Solution Approach 1:
The stent is divided into multiple modular segments or cells that can independently deform. This segmentation allows different portions of the stent to perform different functions: some segments provide radial support while others can collapse or deform to accommodate branch lumens, preventing obstruction while maintaining overall structural integrity
Solution Approach 2:
The stent incorporates dynamic elements such as hinge joints, articulating segments, or shape-memory materials that allow the stent to change its configuration in response to physiological conditions. This enables the stent to adapt between a compressed state for delivery and an expanded state for support, while also allowing temporary deformation to access or accommodate branch lumens
2Adaptability or versatility
If a knitted stent configuration is used to provide superior flexibility, then the stent can adapt to complex anatomy, but it has limitations with re-constrainment and repositioning
Solution Approach 1:
The stent is constructed as an assembly of discrete modular units connected by articulating joints or flexible connectors. This modular design provides flexibility to conform to complex anatomical geometries while allowing each module to be independently manipulated, facilitating repositioning and re-constrainment without requiring complete stent removal
Solution Approach 2:
The stent incorporates nested or telescoping components that allow the stent to be compressed into a compact configuration for delivery and repositioning, then expanded to the functional configuration for support. This nesting capability enables easy re-constrainment and repositioning while maintaining the flexibility needed for complex anatomy
3Strength
If a stent is placed to treat a body lumen at and/or adjacent a branch lumen, then the stent can provide structural support, but it may reduce or block fluid flow into or out of the branch lumen
Solution Approach 1:
The stent is divided into segments that can be selectively positioned relative to branch lumens. Some segments provide radial support while others are designed with gaps, hinges, or articulating joints that allow them to deform or open toward branch openings, maintaining structural support for the main lumen while preserving fluid flow pathways to branch lumens
Solution Approach 2:
Different portions of the stent are designed with different mechanical properties and geometries tailored to local anatomical requirements. Areas adjacent to branch lumens feature reduced radial strength, articulating joints, or deformable segments that allow localized adaptation to preserve branch flow, while other areas provide full structural support
Data Source
AI summary
An endoprosthesis includes an elongated tubular member including a filament forming circumferential rows having a plurality of knitted loops and intermediate rungs extending between adjacent knitted loops. The tubular member includes at least one window and may include a plurality of anti-migration loops adjacent the at least one window and configured to shift between first and second positions when unconstrained. Making the endoprosthesis includes forming the plurality of knitted loops and intermediate rungs in a first row of loops and rungs, extending the filament to form a second row of loops and rungs interwoven with the first row, and forming the at least one window without cutting the filament. Placing the endoprosthesis includes positioning the endoprosthesis within a body lumen adjacent a branch lumen, expanding the tubular member to span the branch lumen, and shifting at least some anti-migration loops toward the second position and into the branch lumen.