Localized Bendable Suture Needle for Small Trocar Passage
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Solution Overview
Problem
Conventional suture needles are limited by the size of trocars, requiring smaller needles that increase surgical time and risk wound dehiscence, and larger needles cannot be easily passed through smaller trocars, leading to inefficiencies and potential tissue damage.
Innovation Solution
Manufacturing suture needles with a bendable region by heat-treating martensitic stainless steel alloys to create a flexible section while maintaining strength in the remainder of the needle, allowing for a seagull or folded configuration that reduces overall size for passage through smaller trocars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If larger suture needles are used to close surgical wounds and repair anatomical features, then surgical effectiveness and wound closure quality are improved, but the ability to pass through small trocars is worsened
Solution Approach 1:
The suture needle is divided into distinct functional segments: a rigid proximal section for strength and suture attachment, a bendable intermediate section for flexibility during passage, and a rigid distal section for tissue penetration. This segmentation allows the needle to combine large size for surgical effectiveness with the ability to navigate through small trocars via the flexible intermediate section
Solution Approach 2:
Different sections of the needle have different mechanical properties tailored to their specific functions. The proximal and distal sections maintain high strength and stiffness for structural integrity and tissue penetration, while the intermediate section has reduced stiffness to enable bending and flexibility during trocar passage, resolving the contradiction between overall needle size and passability
2Length of moving object
If smaller suture needles are used to pass through small trocars, then the ability to pass through trocars is improved, but surgical time and risk of wound dehiscence are worsened
Solution Approach 1:
By segmenting the needle into rigid and flexible sections, the invention enables use of larger overall needle dimensions while maintaining the ability to pass through small trocars via the flexible intermediate section, thereby avoiding the time loss associated with multiple passes required by smaller needles
Solution Approach 2:
The needle's mechanical properties are modified through controlled heat treatment that creates a gradient in stiffness along its length. The intermediate section is heat-treated to reduce hardness and increase flexibility, while proximal and distal sections maintain high strength, enabling the needle to bend during passage without requiring multiple attempts
3Strength
If suture needles are made with uniform high strength and stiffness, then needle durability and tissue penetration are improved, but flexibility for passage through trocars is worsened
Solution Approach 1:
The needle exhibits spatially varying mechanical properties: the proximal and distal sections are heat-treated to maintain high strength and stiffness for structural integrity and tissue penetration, while the intermediate section is selectively heat-treated to reduce hardness and increase flexibility, enabling bending during trocar passage without compromising overall needle strength
Solution Approach 2:
The needle is divided into functional segments with differentiated mechanical properties. The rigid segments provide strength and stiffness where needed, while the flexible intermediate segment provides adaptability for navigation, resolving the contradiction between uniform strength and localized flexibility
4Strength
If conventional heat treatment is applied uniformly to suture needles, then overall hardness and strength are improved, but ability to create bendable regions is worsened
Solution Approach 1:
The heat treatment process is applied non-uniformly along the needle length. The intermediate section undergoes heat treatment at temperatures and durations that reduce hardness and increase flexibility, while proximal and distal sections are heat-treated to achieve high hardness and strength, creating localized bendable regions without compromising overall needle integrity
Solution Approach 2:
The heat treatment parameters (temperature, time, cooling rate) are varied along the needle length to create different mechanical properties in different sections. The intermediate section is heat-treated to produce a softer, more flexible microstructure, while end sections are heat-treated to produce a harder, stronger microstructure, enabling both flexibility and strength in the same needle
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
Enables passage of larger suture needles through smaller trocars, reducing surgical time and minimizing tissue damage by providing flexibility where needed without compromising strength and stiffness.
Implementation Method 1
heating the suture needle to a first temperature that is greater than the austenitic transition temperature of the martensitic alloy
Implementation Method 2
quenching the suture needle to room temperature to harden the martensitic alloy
Implementation Method 3
locally heating the bendable region of the suture needle to a second temperature that is above 800 degrees Celsius, but below the austenitic transition temperature of the martensitic alloy so that the bendable region is softened
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3~4B
AI summary
A method of making a suture needle (10) having a bendable region includes obtaining a suture needle made of a martensitic alloy having an austenitic transition temperature. The suture needle has a proximal section, a distal section with a sharpened tip, and a bendable region located between the proximal and distal sections. The method includes heating the suture needle to a first temperature that is greater than the austenitic transition temperature of the martensitic alloy and quenching the suture needle to room temperature to harden the martensitic alloy. After heating and quenching, the bendable region of the suture needle is heated locally to a second temperature that is above 800 degrees Celsius, but below the austenitic transition temperature of the martensitic alloy so that the bendable region is softened and made more flexible relative to the proximal and distal sections of the suture needle. The locally heating of the bendable region is by electrical resistance heating, laser heating, induction heating, flame heating, or hot gas heating. The suture needle is tempered to improve ductility.