Radiation Sterilized Composite Urinogenital Stent
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Solution Overview
Problem
Existing urinogenital stents lack effective modulation of residence time in conduits, insertion methods that preserve stent integrity, and optimal sterilization methods, particularly for absorbable devices, which are crucial for patient comfort and clinical efficacy.
Innovation Solution
A fiber-reinforced, composite, absorbable/disintegratable stent with a radiopaque hybrid composition, sterilized using radiochemical or radiation methods to control absorption and strength retention profiles, incorporating hydrophilic additives for lubricity and bioactive agents to prevent infection, packaged for controlled radiation exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ethylene oxide sterilization is used for absorbable stent devices, then sterility is achieved, but the absorption rate and mechanical properties of the stent are compromised
Solution Approach 1:
The patent changes the sterilization parameter from ethylene oxide to radiation sterilization (gamma rays or electron beam) at controlled doses of 25-40 kGy. This parameter change achieves sterility while preserving the stent's absorption rate and mechanical properties, as radiation sterilization does not chemically degrade the absorbable polymer materials like ethylene oxide does.
Solution Approach 2:
The patent replaces the chemical sterilization mechanism (ethylene oxide gas penetration and alkylation) with a physical sterilization mechanism (radiation sterilization through ionizing radiation). This substitution eliminates the harmful chemical interactions between ethylene oxide and the absorbable polymer, thereby maintaining the stent's intended degradation profile and mechanical strength.
2Ease of operation
If the stent is designed to be absorbable/disintegratable for temporary support, then patient comfort is improved, but the residence time control and structural integrity are compromised
Solution Approach 1:
The patent employs composite materials consisting of absorbable polymers (such as polyglycolic acid, polylactic acid, or their copolymers) combined with radiopaque fillers (like barium sulfate or titanium dioxide) and reinforcing fibers. This composite structure allows the stent to maintain sufficient mechanical integrity and controlled residence time (typically 4-12 weeks) while remaining biocompatible and absorbable, thus ensuring patient comfort without sacrificing structural control.
Solution Approach 2:
The patent applies different material properties to different parts of the stent structure. The radial support zones contain higher concentrations of radiopaque fillers and reinforcing fibers to maintain structural integrity during the residence period, while the longitudinal sections have optimized polymer composition for controlled degradation. This local differentiation enables precise control of residence time while maintaining patient comfort throughout the stent's functional period.
3Reliability
If radiation sterilization at high dose (25-40 kGy) is applied, then sterility is ensured and absorption rate is modulated, but the mechanical strength of the stent is reduced
Solution Approach 1:
The patent incorporates radiopaque fillers (barium sulfate, titanium dioxide) and reinforcing fibers into the absorbable polymer matrix to create a composite structure that can withstand radiation sterilization at 25-40 kGy. The composite formulation maintains mechanical strength by distributing stress throughout the structure, preventing excessive degradation even at high radiation doses that ensure sterility and modulate absorption rates.
Solution Approach 2:
The patent optimizes the radiation dose parameter within the range of 25-40 kGy, balancing three critical outcomes: achieving complete sterility, modulating the absorption rate to match the clinical residence time requirement, and maintaining sufficient mechanical strength. This parameter optimization is achieved through careful selection of polymer composition, filler content, and fiber reinforcement levels that collectively resist radiation-induced degradation while achieving the desired sterilization and absorption modulation.
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 stent achieves a controlled residence time of 1-10 weeks in urinogenital conduits, ensuring patient comfort and effective infection prevention, with reproducible sterility and strength retention, addressing the limitations of previous stent technologies.
Implementation Method 1
radiation sterilized with 25 to 40 kGy of high-energy radiation to modulate its residence time
Implementation Method 2
radiochemically sterilized or radiation sterilized using the proper dose to modulate its residence time
Implementation Method 3
the matrix component comprises an absorbable, high molecular weight, low-crystallinity, segmented polyaxial copolyester... and hydrophilic polymeric additive
Data Source
AI summary
A radiation sterilized, multi-component, absorbable/disintegratable urinogenital stent, such as an endoureteral stent comprising a load-bearing, radiopaque central coil, said coil comprising an absorbable polyester/inorganic radiopaque hybrid composition, said coil being shrouded with a knitted mesh comprising an absorbable multifilament yarn, to provide a knitted core, said knitted core being impregnated with a polymer matrix comprising an absorbable, segmented, polyaxial copolyester and a polyethylene glycol additive, and said stent being sterilized treated with high-energy radiation at a dose between 25 and 40 kGy.