Star-Configuration Stone Extracting Cannula for Reliable Capture
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Solution Overview
Problem
Current medical stone extracting devices face challenges in capturing stones in larger renal environments due to limited radial expansion, leading to opening malfunctions and incomplete stone capture.
Innovation Solution
The introduction of more than four annularly arranged tubular elements with wire elements connected to non-adjacent tubular elements, forming a star configuration that prevents inversion and ensures proper radial expansion for effective stone capture, as seen in five and six element devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If four wire elements are used in a four-pointed star configuration, then the device structure is simple, but the device experiences opening malfunctions and cannot reliably capture stones in larger renal environments
Solution Approach 1:
The device is divided into multiple independent wire elements (five or six) that can be individually connected to tubular elements. This segmentation allows the system to overcome the limitations of four-element configurations by distributing the mechanical load and geometric constraints across more segments, preventing the inversion and opening malfunctions that occur in four-pointed star configurations.
Solution Approach 2:
The patent transitions from a two-dimensional four-pointed star configuration to a three-dimensional arrangement of five or six wire elements connected to non-adjacent tubular elements. This dimensional change creates a more robust geometric configuration that maintains stability during radial expansion and prevents the wire elements from inverting or closing the open center.
2Area of stationary object
If the radial expansion of tubular elements is increased to capture larger stones, then the capture space is enlarged, but the distance between adjacent backup tubular elements increases making stone capture problematic
Solution Approach 1:
The backup tubular elements are segmented into multiple discrete components (five or six elements) arranged annularly. This segmentation allows the structure to expand radially to capture larger stones while maintaining multiple contact points with the stone surface, ensuring reliable capture even at expanded configurations.
Solution Approach 2:
The wire elements are strategically connected to non-adjacent tubular elements rather than adjacent ones, creating a distributed geometric pattern. This local quality arrangement ensures that when the tubular elements expand radially, the wire elements maintain appropriate tension and geometric relationships that facilitate stone capture across various sizes.
3Ease of manufacture
If wire elements are connected to adjacent tubular elements in a four-element device, then the structure is straightforward, but the device cannot maintain proper opening configuration and experiences inversion
Solution Approach 1:
The patent employs asymmetric connections where wire elements are connected to non-adjacent tubular elements rather than adjacent ones. This asymmetric arrangement creates a geometric configuration that prevents inversion and maintains stable opening throughout the radial expansion cycle, while the manufacturing process remains relatively simple through standardized connection techniques.
Data Source
AI summary
A medical device comprising a cannula having a stone extracting unit on its distal end and a hand piece on its proximal end for operating the unit through the cannula. The unit includes more than four annularly arranged tubular elements with fixed proximal ends and distal ends movable between opened and closed position by the movement of an equal number of wire elements extending through the tubular elements with their distal free ends fixed to the distal ends of tubular elements so as to define a 5 or 6 pointed star configuration.