Biopsy Needle Assembly With Excising Finger for Full-Core Sampling
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Solution Overview
Problem
Existing core biopsy devices face challenges in obtaining full core samples without damaging the sample or causing excessive tissue damage, particularly with non-notched stylet cannulas, and in ensuring secure extraction of the sample during withdrawal.
Innovation Solution
A full core biopsy device with a spoon cannula and coring cannula assembly, featuring an excising finger that severs the sample without rotation, allowing for controlled advancement and separation of the biopsy specimen from the tissue mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a non-notched stylet cannula is used to obtain a full core biopsy sample, then the sample size is increased (full core vs partial core), but the sample may not be securely severed from the tissue mass and could be pulled out during withdrawal
Solution Approach 1:
The cutting edge is divided into two distinct components: a first cutting edge on the stylet that partially severs the tissue, and a second cutting edge on the cannula that completes the severing. This segmentation allows the stylet to create an initial cut while the cannula finalizes the separation, ensuring secure full-core sample retention without requiring the stylet alone to complete the entire cutting action.
Solution Approach 2:
The stylet with its first cutting edge performs a preliminary cutting action by partially severing the tissue before the cannula is withdrawn. This preliminary action creates a pre-cut that reduces the force required for complete separation and ensures the sample is already partially detached, making the subsequent complete severing by the second cutting edge more effective and secure.
2Reliability
If the cannula is rotated during biopsy to attempt severing the sample, then sample retention may be improved, but tissue damage is increased
Solution Approach 1:
The cutting function is segmented between two non-rotating components: the stylet's first cutting edge and the cannula's second cutting edge. This eliminates the need for rotational motion to achieve complete severing, as the linear advancement of these two cutting edges working in sequence accomplishes the same result without the harmful rotational forces that damage surrounding tissue.
Solution Approach 2:
Instead of using rotation to achieve severing (conventional approach), the invention inverts the approach by using linear advancement of a second cutting edge on the cannula to complete the cut initiated by the stylet. This inverted methodology achieves secure sample retention through translational motion rather than rotational motion, thereby reducing tissue damage.
3Reliability
If a notched stylet is used to securely retain the sample, then sample retention is improved, but the sample cross section is reduced (partial core instead of full core)
Solution Approach 1:
The cutting action is segmented between the notched stylet and the cannula with the second cutting edge. The stylet's notch creates a partial core cut, and the cannula's second cutting edge completes the full core severing. This segmentation allows the final sample cross-section to match the full cannula diameter rather than being limited to the smaller stylet notch diameter, while still maintaining secure retention through the combined cutting action.
Solution Approach 2:
The notched stylet performs a preliminary cutting action that creates a partial core, preparing the tissue for complete severing. This preliminary action by the stylet, followed by the completing action of the cannula's second cutting edge, allows the final sample to achieve full core dimensions while the stylet notch provides initial retention security during the process.
Data Source
AI summary
A full core biopsy device includes a needle assembly having stylet, spoon, and at least one coring cannula. A window is located in at least one of the spoon and coring cannula. An excising finger is configured to prolapse through the window into a lumen of the inner spoon or cannula to sever a tissue sample upon translation or axial advancement of the excising finger.