Composite Suture Needle With Nitinol Sheath for Small Cannula Access
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Solution Overview
Problem
Current surgical suture needles face challenges in being passed through smaller cannulas due to size limitations, leading to plastic deformation and reduced strength, especially in minimally invasive surgeries, where larger curved needles are needed but cannot fit through standard 5 mm cannulas, resulting in longer procedures and potential tissue damage.
Innovation Solution
A composite suture needle is developed, featuring a core made of strong stainless steel alloys and a highly elastic nitinol sheath, allowing the needle to be elastically deformed for passage through smaller cannulas without plastic deformation, maintaining strength and returning to its original shape for suturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a larger curved suture needle is used for closing surgical wounds and repairing anatomical features, then the suturing effectiveness is improved, but the needle cannot be passed through smaller cannulas (e.g., 5 mm cannulas)
Solution Approach 1:
The suture needle is divided into multiple sections with different properties: a rigid proximal section for strength and suturing, a flexible intermediate section for navigation through cannulas, and a distal section for tissue engagement. This segmentation allows the needle to兼具 large size for effective suturing and small profile for cannula passage.
Solution Approach 2:
The needle employs materials with different mechanical properties (rigid stainless steel for strength, flexible alloy for deformability) in different sections, changing the physical parameters of flexibility and rigidity along the needle length. This allows the needle to be flexible enough to pass through 5 mm cannulas while maintaining sufficient rigidity for effective suturing.
2Length of moving object
If a smaller suture needle is used to pass through smaller cannulas, then the needle can be inserted through the cannula, but the surgeon must make many more passes through tissue which lengthens the surgical procedure
Solution Approach 1:
The needle's segmented design with a large overall size allows it to engage more tissue in a single pass, while the flexible intermediate section enables it to navigate through small cannulas. This resolves the contradiction by allowing large-needle effectiveness through small-access pathways.
Solution Approach 2:
By changing the flexibility parameter along the needle length (rigid-fFlexible-rigid gradient), the needle achieves both small cannula compatibility and large tissue engagement capability, reducing the number of passes required compared to uniformly small needles.
3Length of moving object
If a smaller sized suture is attached to a smaller suture needle, then the suture can be passed through tissue, but the suture may cut through the tissue (cheese wire effect)
Solution Approach 1:
The needle's proximal rigid section provides sufficient structural support for attaching larger sized sutures, while the overall needle design remains compatible with small cannulas. This allows larger sutures to be used (improving tissue holding capability) without requiring larger cannulas.
Solution Approach 2:
The rigid stainless steel proximal section changes the mechanical parameter of stiffness, providing adequate support for larger suture attachment and preventing the cheese wire effect, while the flexible intermediate section maintains cannula compatibility.
4Length of moving object
If a suture needle made of superelastic alloys (nitinol) is used to enable curved needle to be straightened for passing through cannula, then the needle can be passed through smaller cannulas, but the needle is very difficult to process resulting in high production costs
Solution Approach 1:
Instead of making the entire needle from superelastic nitinol alloy, only the intermediate section requires high deformability. The proximal and distal sections use conventional stainless steel that is easier to process. This local application of special material properties reduces overall manufacturing complexity and cost.
Solution Approach 2:
The needle uses a gradient of material properties rather than uniform superelastic material, changing the flexibility parameter only where needed (intermediate section). This allows conventional manufacturing processes for most of the needle while achieving the required deformability for cannula passage.
5Length of moving object
If a suture needle is elastically deformed for passing through smaller cannulas, then the needle can be inserted through the cannula, but the needle undergoes plastic deformation requiring re-shaping after entering the surgical site
Solution Approach 1:
The flexible intermediate section is designed to undergo elastic deformation for cannula passage, while the rigid proximal and distal sections maintain shape stability. This local flexibility prevents plastic deformation of the critical suturing portions of the needle.
Solution Approach 2:
The needle employs a flexibility gradient along its length, with the intermediate section having high elastic deformability for navigation while the end sections maintain rigid shape stability for suturing functions, preventing permanent deformation.
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 composite suture needle effectively passes through smaller cannulas without plastic deformation, maintaining strength and returning to its original shape for optimal suturing, addressing the limitations of existing needles in minimally invasive surgeries.
Implementation Method 1
surgeons cannot pass the larger suture needles through the 5 mm cannulas so they are forced to use only smaller suture needles... suture needles made of superelastic alloys having shape memory properties, which enable a curved suture needle to be straightened for being passed through a cannula. When the superelastic suture needle is removed from the other end of the cannula for use at a surgical site, the shape memory properties of the needle return it back to the original curved shape.
Implementation Method 2
suture needles made of superelastic alloys having shape memory properties, which enable a curved suture needle to be straightened for being passed through a cannula
Implementation Method 3
A composite suture needle is developed, featuring a core made of strong stainless steel alloys and a highly elastic nitinol sheath, allowing the needle to be elastically deformed for passage through smaller cannulas without plastic deformation, maintaining strength and returning to its original shape for suturing.
Data Source
AI summary
A composite suture needle configured for passing through a smaller cannula used in minimally invasive surgery includes a curved elongated body made of stainless steel. The curved elongated body has a proximal end and a distal end with a pointed tip. The composite suture needle includes a sheath overlying the curved elongated body. The sheath is curved for conforming to the shape of the curved elongated body. The sheath is made of a material that is more elastic than the curved elongated body. The pointed tip of the curved elongated body extends distally beyond the distal end of the sheath. The curved elongated body is made of stainless steel and the sheath is made of a material, such as nitinol, that is more elastic than the elongated body.