Flexible Guide for Stent Positioning Through Urethral Sphincter
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Solution Overview
Problem
Existing devices for inserting endo-urethral stents through the urinary striated sphincter often fail to accurately position the stent on both sides of the sphincter, leading to frequent reinsertion and the need for additional visualization techniques like endoscopy or trans-rectal ultrasound due to unclear tactile feedback from existing expandable members.
Innovation Solution
A guide with a flexible part that can reversibly deform from a straight to a bent position, providing significant resistance change upon passing through the sphincter, allowing for correct positioning of the stent with minimal external force and preventing injury, comprising a pusher tube, stent, and thread for secure placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an expandable member (balloon or Malecot arrangement) is used to abut against the sphincter for positioning the stent, then the stent can be inserted through the sphincter, but the tactile feedback is not clearly perceived by the operator leading to incorrect positioning
Solution Approach 1:
The guide changes its flexibility parameter dynamically: it is flexible enough to deform and follow the urethral curvature during insertion, then becomes rigid after passing the sphincter to maintain positioning. This parameter change enables clear tactile feedback (rigid state) while facilitating passage (flexible state), resolving the contradiction between ease of operation and positioning accuracy.
Solution Approach 2:
The guide transitions from a flexible state during insertion to a rigid state after passing the sphincter. This dynamic change allows the guide to adapt to the urethral geometry initially, then provide stable tactile feedback and precise positioning afterward, solving the problem of unclear tactile feedback leading to incorrect positioning.
2Object-affected harmful factors
If minimal external forces are applied to deform the device through the obstacle, then injury to the natural canal is prevented, but the device may not generate sufficient tactile feedback for accurate positioning
Solution Approach 1:
The guide's rigidity parameter changes after passing the sphincter, transforming from flexible to rigid. This allows minimal force application during insertion (preventing injury) while generating strong tactile feedback once the guide engages the sphincter anatomy (providing positioning information), thus resolving the contradiction between injury prevention and feedback signal strength.
3Ease of operation
If the lower tubular element is pushed through the sphincter, then the stent can be positioned above the sphincter, but the element is often pushed too above leading to the stent being released too far inside the bladder
Solution Approach 1:
The guide provides clear tactile feedback when it passes through the sphincter and engages the prostatic urethra anatomy. This feedback mechanism allows the operator to stop insertion at the correct position, preventing over-insertion that would cause the stent to be released too far inside the bladder, thus resolving the contradiction between ease of operation and positioning precision.
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 precise and safe insertion of stents through natural canals by providing clear tactile feedback during passage through anatomical obstacles, ensuring correct positioning without causing injury and reducing the need for additional visualization methods.
Implementation Method 1
a flexible part having a predetermined longitudinal stiffness and a lateral flexibility consisting in a reversible deformation from a straight position to a bent position so as to follow the curve of the natural canal under the application of minimal external forces applied by an operator
Implementation Method 2
The progression of the device cannot continue unless the operator applies to the device a force that will more deform the canal
Data Source
AI summary
A device for positioning a stent in a natural canal after passing through an obstacle at the level of a target organ. The device includes a stent, a pusher tube, and a guide. The guide is configured to push the stent through the lumen of the natural canal, and includes at least one flexible part having a predetermined longitudinal stiffness and a lateral flexibility that allow a reversible deformation from a straight position to a bent position so as to follow the curve of the natural canal under the application of minimal external forces exerted by an operator. The device is particularly adapted to the technical field of urology.