Self-Retaining Suture Retainers with Enlarged Apex Radius
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Solution Overview
Problem
Existing sutures face challenges in maintaining secure positioning within tissue due to high stress concentrations at the retainer apex, leading to potential fracture and failure, especially when pulled in directions opposite to insertion.
Innovation Solution
The development of sutures with retainers featuring an upper surface and lower surface defined by a cutting edge, where the lower surface has a radius of curvature larger than the cutting edge, and the use of a heated cutting edge to form and anneal the retainers, reducing stress concentrations and enhancing pull-out strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If retainers are formed with a sharp cutting edge to enable clean tissue penetration, then ease of insertion is improved, but stress concentration at the retainer apex increases leading to potential fracture
Solution Approach 1:
The retainer is designed with non-uniform geometry: the leading edge maintains a sharp cutting angle for tissue penetration, while the apex (rear portion) is enlarged to a radius of curvature between 0.05mm and 0.5mm. This local variation in geometry allows the sharp edge to perform its cutting function while the enlarged apex distributes stress to prevent fracture.
Solution Approach 2:
The retainer geometry is designed in advance with an enlarged apex that acts as a stress-distributing feature. This pre-designed geometric modification cushions the concentration of forces that would otherwise occur at the sharp apex, preventing fracture before it occurs during tissue engagement.
2Manufacturing precision
If retainers are made with a small radius of curvature at the apex for precise positioning, then positioning precision is improved, but stress concentration increases reducing reliability
Solution Approach 1:
The retainer incorporates localized geometric variation where the apex radius is specifically enlarged to 0.05mm-0.5mm while maintaining precise control over the retainer's overall dimensions and orientation. This local modification improves reliability without sacrificing positioning precision.
3Strength
If retainers are designed to resist movement in the opposite direction of insertion, then anchoring strength is improved, but stress on the retainer apex increases leading to potential failure
Solution Approach 1:
The retainer geometry features a sharp leading edge for insertion and an enlarged apex with 0.05mm-0.5mm radius of curvature. This local geometric modification allows the retainer to resist pull-out forces effectively while the enlarged apex prevents stress concentration that would lead to fracture during reverse-direction loading.
Solution Approach 2:
The enlarged apex is designed into the retainer structure beforehand to cushion and distribute the high stresses that occur when the retainer resists movement in the opposite direction of insertion, preventing fracture while maintaining anchoring strength.
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 solution significantly reduces stress concentrations at the retainer apex, improving the suture's resistance to movement and reducing the likelihood of failure, thereby enhancing the suture's ability to securely anchor within tissue.
Implementation Method 1
the use of a heated cutting edge to form and anneal the retainers
Implementation Method 2
the use of a heated cutting edge to form and anneal the retainers, reducing stress concentrations
Data Source
AI summary
An embodiment of a suture for use in a surgical procedure applied to tissue comprises an elongated body having a first end and a second end, and a plurality of retainers arranged along a portion of the elongated body. The retainers substantially yield to motion of the elongated body within the tissue when the elongated body is drawn at the first end and resist motion of the elongated within the tissue when the elongated body is drawn at the second end. The retainers include an upper surface and a lower surface, the upper surface extending from a periphery of the elongated body and the lower surface having at least two facets.