Elastic Suture Needle Design for Minimally Invasive Surgery
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Solution Overview
Problem
Surgeons face difficulties in passing larger suture needles through smaller cannulas during minimally invasive surgeries due to size limitations, leading to increased procedural time and risk of dehiscence, and challenges with securing sutures to Nitinol needles result in weak attachments and high production costs.
Innovation Solution
Development of elastic suture needles made from martensitic-aged or austenitic stainless steels that can be elastically deformed to fit through smaller cannulas, returning to their original shape for use, and utilizing a needle driver with clamping jaws to protect the tip during passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If larger suture needles are used for closing surgical wounds, then suture attachment strength and wound closure reliability are improved, but the ability to pass the needle through smaller cannulas deteriorates
Solution Approach 1:
The suture needle is designed with dynamic shape memory properties that allow it to change its configuration from a curved state (for passing through cannulas) to a straight state (for suturing operations). The needle can be deformed elastically during passage through the cannula and returns to its original curved shape after use, enabling larger needles to pass through smaller cannulas without permanent deformation
Solution Approach 2:
The needle's physical state is changed by controlling the elastic deformation parameters during cannula passage. By carefully controlling the force applied and the needle's material properties, the needle undergoes reversible elastic deformation to fit through the cannula opening and then returns to its original configuration for surgical use
2Ease of operation
If smaller suture needles are used to pass through smaller cannulas, then ease of passage is improved, but procedural time and risk of dehiscence worsen
Solution Approach 1:
The shape memory needle allows surgeons to use larger needles that require fewer passes through tissue. The needle's ability to be deformed elastically during passage and then return to its original shape enables single-pass suturing with larger needles, significantly reducing procedural time compared to using smaller needles that require multiple passes
3Ease of operation
If Nitinol superelastic suture needles are used, then ability to pass through smaller cannulas is improved, but production cost and manufacturing complexity worsen
Solution Approach 1:
The patent uses conventional stainless steel alloys (4310, 420, 304) instead of expensive Nitinol superelastic alloys. These cheaper materials achieve the same elastic deformation capability through controlled heat treatment and manufacturing processes, significantly reducing production costs while maintaining the required elastic recovery for cannula passage
Solution Approach 2:
The material's elastic properties are achieved through controlling heat treatment parameters and microstructure rather than relying on expensive superelastic alloys. The stainless steel is heat-treated to achieve the necessary elastic deformation characteristics, providing cost-effective elastic behavior without requiring Nitinol
4Strength
If larger suture needles are passed through smaller cannulas, then suture size and strength are improved, but risk of plastic deformation and needle failure worsens
Solution Approach 1:
The needle is designed to undergo reversible elastic deformation during cannula passage rather than permanent plastic deformation. The elastic deformation allows the needle to flex and straighten during passage, then return to its original curved shape for surgical use, maintaining reliability and preventing permanent damage
Solution Approach 2:
The needle's elastic properties are engineered in advance to provide a cushioning effect during passage through the cannula. The material and geometry are designed to absorb the mechanical stress of passage elastically, preventing plastic deformation and ensuring the needle returns to its original state without damage
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 the use of larger suture needles through smaller cannulas without plastic deformation, reducing procedural time and improving suture attachment strength while lowering production costs by avoiding superelastic materials like Nitinol.
Implementation Method 1
The suture needle is elastically straightened as it is passed through the cannula and the springs back to its original curvature upon being removed from an end of the cannula for use in surgery
Implementation Method 2
Development of elastic suture needles made from martensitic-aged or austenitic stainless steels that can be elastically deformed to fit through smaller cannulas, returning to their original shape for use
Data Source
AI summary
An elastic suture needle for passing through a smaller cannula used in minimally invasive surgery includes an elongated body having a proximal end, a distal end, a length extending from the proximal end to the distal end, a top surface extending along the length of the elongated body, and a bottom surface extending along the length of the elongated body. The elongated body has dimensions that are calculated using the equation T/LN< (2*σ)/(πE), where T is the thickness of the elongated body, LN is the length of the neutral axis of the elongated body, σ is the yield strength of the elongated body, and E is the Young’s modulus of the elongated body. The elongated body is made of stainless steels such as martensitic stainless steels, austenitic stainless steels, martensitic-aged (mar-aged) stainless steels, and stainless steels sold under the registered trademark ETHALLOY® Needle Alloy.