Rigid Kidney Stone Extractor With Segmented Cannula Control
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Solution Overview
Problem
Current surgical retrieval devices for kidney stones and calculi often cause tissue damage and bleeding due to their flexible and difficult-to-control nature, and may not effectively remove stones larger than 6mm in diameter.
Innovation Solution
A rigid extractor system comprising a fixed outer cannula and a handle-actuated inner cannula with a removable extraction device, such as a basket or grasper, made from shape-memory materials, which provides better control and minimizes tissue trauma by using atraumatic designs and adjustable force mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flexible catheters and wires are used to engage and remove stones, then the device can navigate through body passages, but the device becomes difficult to control and causes tissue damage and bleeding
Solution Approach 1:
The device is divided into distinct segments: a rigid outer cannula for structural support and navigation, a removable inner cannula for controlled movement, and a separate extraction device (basket or grasper) for stone engagement. This segmentation allows each component to perform its specific function optimally while minimizing tissue trauma.
Solution Approach 2:
The rigid outer cannula acts as an intermediary structure that provides stable support and control during the extraction procedure. It serves as a mediator between the operator's manual control and the delicate extraction device, enabling precise positioning and reduced tissue damage compared to fully flexible devices.
2Adaptability or versatility
If flexible graspers are used for stone removal, then the device can adapt to different positions, but the flexibility makes the device difficult to control precisely
Solution Approach 1:
The device separates the adaptability function (extraction device that can open and close) from the control function (rigid cannula that provides stable positioning). The extraction device adapts to different stone positions while the rigid cannula maintains precise control during manipulation.
Solution Approach 2:
The inner cannula is designed to be removable and interchangeable, allowing dynamic adaptation of the extraction device based on the specific procedure requirements. The rigid outer cannula remains static for stable control while the inner components can be changed to suit different extraction needs.
3Ease of operation
If rigid extractors are used to control extraction devices, then control and precision are improved, but the device complexity increases
Solution Approach 1:
The rigid extractor system is segmented into modular components: outer cannula, inner cannula, and extraction device. This segmentation allows for standardized manufacturing of each component and simplifies assembly and sterilization procedures despite the overall system complexity.
Solution Approach 2:
The rigid outer cannula serves multiple functions: providing structural support, enabling precise positioning, protecting surrounding tissues, and facilitating the removal of the inner cannula and extraction device. This multi-functionality reduces the need for additional specialized components.
4Manufacturing precision
If conventional graspers are used for kidney stones, then small stones can be removed, but stones larger than 6mm cannot be effectively removed
Solution Approach 1:
The extraction device parameters (basket size, grasper jaw dimensions) can be changed by replacing the inner cannula and extraction device assembly. This allows the same rigid outer cannula system to handle stones of varying sizes from small fragments to stones exceeding 6mm in diameter, improving both precision and productivity.
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 system allows for safer and more controlled retrieval of kidney stones and calculi, reducing tissue damage and bleeding, and enabling the removal of stones up to 6mm or larger in diameter with greater precision and efficiency.
Implementation Method 1
The inner cannula is made from a shape-memory material and has a transformed shape in which the extraction device is extended from the outer cannula
Data Source
Figure 1a~2c
Figure 1b
Figure 1c~1d
AI summary
A rigid extractor (10) is revealed, a rigid device for use in percutaneous procedures to remove kidney stones directly from the kidneys. The rigid extractor (10) uses a handle (16) fixed to an outer rigid cannula (12), and an inner cannula (14) to control an extraction device (18) that may be removable from the inner cannula (14). The extractor (10) is desirably used with a fluoroscope, in which the surgeon maneuvers the extractor (10) with the aid of a view of the operating field provided by the fluoroscope. The surgeon then maneuvers the extractor (10) to grasp the kidney stones and remove from the patient. The extractor (10) may also be used with a nephroscope. The device may be used with a removable extraction device (18) such as a basket, a grasper, a pair of jaws, or a pair of scissors.