Locally Reversible Barbed Sutures With Asymmetric Geometry
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Solution Overview
Problem
Existing barbed sutures are not locally reversible without causing tissue trauma or damaging the barbs, and they are prone to damage due to the monofilament suture design, which limits their ability to approximate tissue effectively.
Innovation Solution
A flexible filament with barbs that have a leading edge, a trailing edge, and a blunt tip, where the trailing edge defines an angle of at least 68° relative to the filament's longitudinal axis, allowing for minimal resistance when passed through tissue in one direction and greater resistance in the opposite direction, reducing tissue trauma and barb damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If barbed sutures are designed with barbs cut into a monofilament suture to provide holding strength, then wound holding strength is improved, but the barbs become prone to damage and the suture loses local reversibility
Solution Approach 1:
The suture is segmented into multiple filaments (e.g., 2-10 filaments) rather than using a single monofilament. Each filament can independently flex and recover, distributing stress across multiple elements. This segmentation prevents catastrophic failure of individual barbs and maintains suture functionality even when some barbs are damaged during passage or adjustment.
Solution Approach 2:
The barb geometry parameters are optimized with specific angle ranges (acute angle between 30-60 degrees, obtuse angle between 120-150 degrees) and dimensional relationships (barb length 0.5-2.0mm). These parameter changes enable the barbs to engage tissue effectively while reducing stress concentration that leads to barb fracture or deformation.
2Strength
If barbed sutures are designed for unidirectional passage through tissue to maximize holding strength, then tissue approximation capability is improved, but local reversibility is lost causing tissue trauma when adjustment is needed
Solution Approach 1:
The barbs exhibit asymmetric geometry with distinct leading edges (acute angles 30-60 degrees) and trailing edges (obtuse angles 120-150 degrees). This asymmetry creates directional engagement where the acute leading edge cuts through tissue with minimal resistance during forward passage, while the obtuse trailing edge provides strong anchoring resistance to reverse motion, enabling controlled local reversibility when needed.
Solution Approach 2:
The suture system transitions from a static, permanently locked configuration to a dynamic system where barbs can be temporarily engaged or disengaged. The multi-filament construction with optimized barb angles allows the suture to be passed through tissue, held in position, and then locally reversed or adjusted without causing trauma or permanent damage to the barb structure.
3Ease of operation
If barbs are designed with acute leading edges to minimize drag during passage, then ease of insertion is improved, but holding strength in the opposite direction is reduced
Solution Approach 1:
The barb design employs asymmetric angles where the leading edge has an acute angle (30-60 degrees) for minimal tissue disruption during insertion, while the trailing edge has an obtuse angle (120-150 degrees) that provides strong mechanical interlocking and holding strength. This asymmetric geometry resolves the contradiction by optimizing each edge for its specific functional requirement.
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3A~3B
AI summary
A wound closure device includes a flexible filament having a first end, a second end, and a longitudinal axis extending between the first and second ends. A plurality of barbs project outwardly from the flexible filament. Each barb has a base connected with the flexible filament, a blunt tip spaced from the base, a leading edge extending between the base and the blunt tip and facing toward the first end of the flexible filament, and a trailing edge extending between the base and the tip and facing toward the second end of the flexible filament. The trailing edge of the barb and the longitudinal axis of the flexible filament define an angle of at least 68 that opens toward the second end of the flexible filament.