Knitted Stent Cell Structure to Prevent C-Fold During Deployment
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Solution Overview
Problem
Conventional knitted stents face challenges in deliverability and form a 'C-fold' when improperly sized, leading to incomplete stricture resolution, stent migration, and lumen blockage.
Innovation Solution
A knitted stent design with alternating loop rows featuring open and closed cells, where closed cells are configured to absorb and elongate filament material, allowing the stent to self-adjust and expand without forming a 'C-fold, even when incorrectly sized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a knitted stent is designed with sufficient radial force to open the body lumen, then the stent can anchor and prevent migration, but the stent becomes difficult to deliver and may form C-folds when improperly sized
Solution Approach 1:
The stent is divided into multiple rows of cells with different configurations (open cells, closed cells, locked cells) that can independently deform during delivery and expansion. This segmentation allows different portions of the stent to perform different functions: some cells provide radial force while others enable flexibility for delivery
Solution Approach 2:
The stent structure transitions from a constrained delivery state to an expanded deployed state through dynamic cell deformation. The cells are designed to change shape and configuration during deployment, allowing the stent to adapt its radial force characteristics based on the deployment phase and sizing conditions
2Strength
If the stent is sized larger than the target lumen, then the stent provides sufficient radial support, but a C-fold forms causing incomplete stricture resolution and lumen blockage
Solution Approach 1:
The stent incorporates cells with varying geometric parameters (open, closed, locked configurations) that change their deformation characteristics based on sizing conditions. When oversized, the locked cells prevent excessive radial expansion that would cause C-folds, while still allowing sufficient expansion to resolve the stricture
Solution Approach 2:
The potential harm of C-fold formation is converted into a benefit by designing locked cells that deliberately restrict expansion in specific configurations. This restriction prevents the harmful C-fold while the overall stent still provides adequate radial support through other cell mechanisms
3Adaptability or versatility
If the stent uses a knitted configuration for flexibility, then the stent can adapt to body lumens, but the stent does not easily lend itself to re-constraint and repositioning
Solution Approach 1:
The knitted structure is segmented into discrete cell units with specific configurations that can be independently constrained. The locked cells and connector elements create discrete constraint points that allow the stent to be re-constrained without compromising overall flexibility
Solution Approach 2:
Different portions of the stent have different cell configurations optimized for specific functions: some areas have higher flexibility for adaptation while other areas have locked cells for re-constraint capability. This local differentiation allows the stent to possess both flexibility and re-constraint properties in different locations
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 design enhances deliverability and adaptability to varying body lumen diameters, preventing 'C-fold' formation and ensuring proper expansion without lumen blockage.
Implementation Method 1
closed cells are configured to absorb and elongate filament material, allowing the stent to self-adjust and expand
Data Source
AI summary
A knitted stent extending along a central longitudinal axis may comprise a filament forming a plurality of cells arranged in a plurality of columns and a plurality of rows. The plurality of rows may extend parallel to the central longitudinal axis. The plurality of columns may extend circumferentially around the central longitudinal axis. The plurality of rows may include a plurality of loop rows and a plurality of rung rows interposed between adjacent loop rows. Each cell within the plurality of loop rows may include a circumferential loop element connected to two longitudinally oriented connector elements. The plurality of rung rows may include a plurality of circumferential rung elements connected to adjacent loop rows. A majority of the plurality of loop rows may include open cells having an open end. At least one of the plurality of loop rows may include a plurality of closed cells having a closed end.