Contoured Barbed Sutures for Easy Tissue Passage and Strong Fixation
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Solution Overview
Problem
Conventional barbed sutures face limitations in achieving enhanced holding strength without increasing insertion force, stiffness, or palpability, and struggle to pass easily through tissue in one direction while maintaining maximum holding strength in the opposite direction.
Innovation Solution
A wound closure device with a stop element having a specific ratio of leading edge area to total surface area less than 10%, combined with barbs that have a unique outer edge shape and spacing to facilitate easy passage and increased holding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the surface area of the stop is increased to provide a larger stop, then the holding strength of the suture is improved, but the device becomes more palpable and the insertion force increases
Solution Approach 1:
The stop element is designed with non-uniform thickness, featuring a thinner leading edge (6-25 mils) that contacts tissue first and a thicker trailing edge (10-30 mils) that provides structural support. This local variation in thickness allows the stop to achieve adequate holding strength through its overall dimensions while maintaining a low-profile leading edge that minimizes palpability and tissue reaction.
Solution Approach 2:
Rather than increasing the surface area of the stop in the traditional planar sense, the invention utilizes the third dimension (thickness) strategically. The stop element achieves its holding function through its length (39-200 mils) and controlled thickness variation, rather than by expanding its footprint area, thereby avoiding increased palpability while maintaining structural integrity.
2Strength
If the barbs are designed to increase holding strength, then the suture secures better in tissue, but the insertion force and stiffness of the suture increase
Solution Approach 1:
The barbs are designed with asymmetric geometry, featuring a concave outer edge that creates a leading surface and a trailing surface. This asymmetry allows the barbs to engage tissue effectively in the holding direction while presenting a lower profile during insertion. The barbs extend 6-25 mils from the filamentary element, providing adequate holding strength without excessive size that would increase insertion force.
Solution Approach 2:
The barbs are distributed along specific portions of the filamentary element rather than uniformly across the entire length. This localized placement of barbs provides holding strength where needed while minimizing the overall stiffness and insertion force requirements of the suture.
3Strength
If the barbs are made larger to increase holding strength, then the suture holds better, but the suture becomes stiffer and more difficult to pass through tissue
Solution Approach 1:
The barb dimensions are precisely controlled within specific ranges: extending 6-25 mils from the filamentary element with a base width of 6-20 mils and a length of 10-30 mils. These parameter optimizations ensure the barbs are large enough to provide adequate holding strength through tissue engagement while remaining small enough to allow flexible passage through tissue without excessive stiffness.
Solution Approach 2:
The barbs feature a concave outer edge with a radius of curvature of 0.002-0.010 inches, which allows the barbs to flex and conform to tissue during insertion while maintaining their holding function. This curvature enables the barbs to pass through tissue more easily by reducing stress concentration and allowing controlled deformation during the insertion process.
Data Source
AI summary
A wound closure device includes a filamentary element having a proximal end and a distal end, and a plurality of barbs extending outwardly from the filamentary element. Each barb has a base connected with the filamentary element, a tip spaced from the base, and an outer edge that extends between the base and the tip. The outer edge includes a first section having a concave surface that extends between the base and a transition point of the barb and a second section having a convex surface that extends between the transition point of the barb and the tip of the barb. The outer edge transforms from the concave surface of the first section to the convex curve of the second section at the transition point of the barb. The tip of the barb has a convexly curved surface facing the distal end of the filamentary element. The unique dual radius shape of the outer edge of the barbs and the tips of the barbs minimizes resistance when the filamentary element is pulled in a first direction through tissue and maximizes resistance to movement when the filamentary element is pulled in an opposite, second direction through tissue for holding the wound closure device stationary.