Undulating Prostatic Urethral Expander for Duct-Sparing Dilation
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Solution Overview
Problem
Existing prostatic stents for treating benign prostatic hyperplasia (BPH) suffer from issues such as migration, encrustation, blockage of ejaculatory and prostatic ducts, pain due to rigidity, and difficulty in removal, as they do not accommodate the unique anatomical characteristics of the prostatic urethra.
Innovation Solution
A resiliently deformable undulating ring expander with longitudinal struts and prongs configured for implantation into the prostatic urethra, allowing for minimal contact with the urethra wall, reducing encrustation and facilitating easy removal, while conforming to the urethra's shape during use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cylindrical stents are used to treat BPH, then immediate relief of urinary flow resistance is achieved, but the stents migrate from deployment position and cause side effects such as encrustation, blockage, and pain
Solution Approach 1:
The stent is divided into multiple segments or struts that can independently engage with the urethral wall, allowing each segment to anchor separately and prevent migration while maintaining overall structural integrity
Solution Approach 2:
Different portions of the stent have different properties - the proximal end has features for anchoring in the bladder neck, the distal end has features for anchoring in the prostatic urethra, and the intermediate sections provide radial support with minimal encrustation surfaces
2Stress or pressure
If circumferential rings are used to expand the prostatic urethra, then radial support is provided, but the rings impinge on the verumontanum and block ejaculatory and prostatic ducts
Solution Approach 1:
The circumferential support is segmented into discrete struts rather than continuous rings, creating gaps that allow urine and seminal fluids to pass through without blockage while maintaining radial support pressure on the urethral wall
Solution Approach 2:
The stent design transitions from a two-dimensional circumferential ring to a three-dimensional structure with longitudinal struts that provide radial support while leaving interstitial spaces for fluid flow through the prostatic ducts and ejaculatory ducts
3Stability of the object's composition
If rigid stent structures are used to maintain urethral patency, then structural stability is achieved, but the rigidity causes pain and impedes natural movements during urination and ejaculation
Solution Approach 1:
The stent incorporates flexible elements and articulation points that allow dynamic movement and deformation during urination and ejaculation, reducing pain while maintaining structural stability for urethral patency
Solution Approach 2:
The stent uses flexible materials and thin-walled structures that can deform elastically during physiological movements, providing structural support without causing pain or impeding natural urethral function
4Stress or pressure
If circumferential struts are used to provide continuous expansion, then radial support is maximized, but encrustation increases due to 90-degree contact with urine flow
Solution Approach 1:
The stent struts are designed with curved surfaces that redirect urine flow at angles other than 90 degrees, reducing turbulence and deposition of minerals that lead to encrustation while maintaining radial expansion pressure
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 undulating ring expander effectively dilates the prostatic urethra, minimizing encrustation and migration, and allows for normal anatomical function without obstructing ejaculatory ducts, providing a more comfortable and effective treatment for BPH.
Implementation Method 1
The expander is typically resiliently deformable in a radial direction between a contracted orientation suitable for transluminal delivery to the target site through the body lumen and an expanded (deployed) orientation configured to effect in-situ dilation of the body lumen at the target site
Data Source
AI summary
A delivery device for image-assisted delivery of an implantable expander in a urethra. An implantable biocompatible expander suitable for implantation into a urinary duct is resiliently deformable from a relaxed radially expanded orientation to a radially contracted orientation suitable for transluminal delivery through the urinary duct. The expander may be configured to exert an outward radial force against a wall of the urinary duct when in-situ within the urinary duct. In particular, the expander is suitable for treatment of benign prostatic hyperplasia and configured for implantation into the prostatic urethra between, and substantially spanning the prostatic urethra between, the bladder neck and external sphincter.