Undulating Urethral Expander for Stable BPH Stent Placement
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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, and difficulty in removal due to their circumferential design and rigidity, which do not accommodate the unique anatomy of the prostatic urethra.
Innovation Solution
A resiliently deformable undulating ring expander with longitudinal struts and prongs that conform to the prostatic urethra's anatomy, minimizing contact area and allowing for differential flexing, reducing encrustation and facilitating easy removal while maintaining urethral patency.
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 migration to bladder or membranous urethra occurs in up to 12.5% of patients
Solution Approach 1:
The stent employs a flexible undulating ring structure with longitudinal struts that can bend and conform to the natural curvature and movements of the prostatic urethra, preventing migration while maintaining positional stability. The flexibility allows the stent to adapt to anatomical variations without dislodging.
Solution Approach 2:
The stent transitions from a static rigid structure to a dynamic flexible structure that can move with the urethra during physiological functions like urination and ejaculation. The undulating design allows dynamic adaptation to changing urethral geometry, ensuring continued stability without migration.
2Reliability
If traditional cylindrical stents are used, then urinary flow resistance is reduced, but encrustation and blockage occur in up to 27.5% of patients
Solution Approach 1:
The flexible undulating structure creates turbulent flow patterns and prevents stagnant zones where encrustation typically forms. The continuous movement and flexibility of the stent disrupts sediment deposition, reducing encrustation and blockage risks while maintaining urethral patency.
Solution Approach 2:
The undulating ring design with curved longitudinal struts promotes fluid flow along the contours of the stent, preventing stagnant areas where encrustation occurs. The curved geometry directs urine flow smoothly, reducing deposition of minerals and debris on the stent surface.
3Strength
If ring-shaped stents are used, then structural support is provided, but difficulty in removal occurs due to rings being embedded at 90° to the longitudinal axis
Solution Approach 1:
The stent is divided into multiple longitudinal segments or struts connected by flexible joints, allowing the structure to be compressed along its longitudinal axis for easy removal. The segmented design maintains structural support when deployed but enables straightforward extraction by collapsing the struts together.
Solution Approach 2:
The stent employs dynamic joints between longitudinal struts that allow the structure to transition from a rigid supported configuration during use to a compressed flexible configuration for removal. This dynamic capability enables easy extraction while maintaining structural integrity during the treatment period.
4Stability of the object's composition
If rigid ring stents are used, then structural stability is maintained, but pain occurs due to impingement on verumontanum and disruption of natural urethral movements
Solution Approach 1:
The flexible undulating structure allows the stent to move with the urethra during urination and ejaculation, preventing impingement on the verumontanum and surrounding tissues. This flexibility eliminates pain-causing friction and pressure points while maintaining adequate structural support for urethral patency.
Solution Approach 2:
The stent's physical parameters such as flexibility, curvature, and strut configuration are optimized to match the physiological parameters of the prostatic urethra. The undulating design with appropriate flexibility metrics allows natural urethral movements without causing pain or inflammation, while still providing necessary structural stability.
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, reducing encrustation and migration risks, and allows for anatomical conformity during urination and ejaculation, enhancing patient comfort and treatment efficacy.
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
Implementation Method 2
The undulating ring configuration of the expander allows for differential flexing of the expander during use, thus allowing the shape of the mirror the anatomical shape, and adhere to, and move with, the shape of the wall of the body lumen
Data Source
AI summary
A catheter for deploying an implantable expander to a target location 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.