Spring-Loaded Knee Model for Wound Closure Testing
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Solution Overview
Problem
Current benchtop models and animal models are inadequate for accurately assessing wound closure products used on human knees and flexible joints, leading to the need for more effective testing systems that can simulate human skin deformation and evaluate the performance of various wound closure products.
Innovation Solution
A mechanical system with a flexible joint, utilizing spring-loaded clamping assemblies and a substrate model that mimics human skin deformation, coupled with a motorized actuator to simulate knee movement and evaluate wound closure products such as adhesives, tapes, and sutures, to assess their effectiveness and tissue holding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If animal skin substrates (e.g., porcine skin) are used in knee models, then the model can be constructed and tested, but the substrate deformation is limited (only 5-10%) compared to human skin deformation (63.8±10.2%)
Solution Approach 1:
A synthetic substrate is introduced as an intermediary material that bridges the gap between animal skin and human skin deformation characteristics. The synthetic substrate is specifically engineered to exhibit deformation properties matching human skin (63.8±10.2% tensile strain) while being used in conjunction with animal skin substrates in the knee model, allowing accurate simulation of human wound closure during knee flexion.
Solution Approach 2:
The deformation parameters of the substrate are changed by replacing or supplementing animal skin with synthetic materials designed to match human skin mechanical properties. The synthetic substrate is formulated to achieve tensile strain values of 63.8±10.2%, fundamentally altering the substrate's elastic and deformable characteristics to accurately represent human skin behavior during knee flexion.
2Reliability
If spring-loaded clamping assemblies are used to compensate for limited substrate deformation, then the system can simulate human skin deformation, but the device complexity increases
Solution Approach 1:
The clamping assemblies are designed with spring-loaded mechanisms that provide dynamic, adjustable clamping forces rather than fixed rigid clamping. The springs allow the clamping force to adapt during knee flexion and extension cycles, accommodating the substrate's deformation while maintaining secure attachment. This dynamic design enables accurate deformation simulation (63.8±10.2% tensile strain) without requiring overly complex mechanical systems.
3Adaptability or versatility
If current bench top models are used, then orthopedic implants can be evaluated, but wound closure products cannot be assessed
Solution Approach 1:
The knee model is designed with universal applicability to evaluate multiple types of medical devices and products. By incorporating a substrate system that accurately simulates human skin deformation (63.8±10.2% tensile strain) and using spring-loaded clamping assemblies for secure attachment, the model can assess both orthopedic implants and wound closure products (sutures, adhesives, tapes, meshes) under physiologically relevant conditions, eliminating the need for separate specialized models.
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 provides a reliable method to evaluate wound closure products by simulating human skin deformation and knee movement, allowing for the identification of products that effectively keep skin edges approximated during rehabilitation exercises and determining maximum tissue holding strength.
Implementation Method 1
springs, such as compression springs, compensate for the limited deformation of the animal tissue by allowing the clamping assembly and tissue substrate to slide back and forth on the knee model during knee flexion and extension cycles
Data Source
AI summary
A system for testing substrates includes a first elongated member including an outer end, an inner end, an outer surface that extends between the outer and inner ends, and a concave surface at the inner end, and a second elongated member including an outer end, an inner end, an outer surface that extends between the outer and inner ends of the second elongated member, and a convex surface at the inner end of the second elongated member that opposes the concave surface at the inner end of the first elongated member. A joint interconnects the first and second elongated members for guiding sliding movement of the concave surface of the first elongated member over the convex surface of the second elongated member between extended and flexed positions. A first clamping assembly is coupled with the first elongated member and at least one first clamping assembly spring normally urges the first clamping assembly away from the inner end of the first elongated member. A second clamping assembly is coupled with the second elongated member and at least one second clamping assembly spring normally urges the second clamping assembly away from the inner end of the second elongated member. A substrate overlying the outer surfaces of the first and second elongated members has a first end secured to the first clamping assembly and a second end secured to the second clamping assembly.