Prosthetic Liner with Low Extensibility Strips
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Prosthetic liners with uniform extensibility fail to address pistoning and skin breakdown issues, as they either constrain knee flexion or lead to distal distraction due to uniform longitudinal elongation, and existing solutions are costly and limited in customization.
Innovation Solution
A prosthetic liner with differentiated knit fabric exterior and low extensibility strips, allowing for variable stretch regions, particularly reduced longitudinal stretch at the distal end and increased transverse stretch, using computerized flatbed knitting machines and various stitches to create customizable, cost-effective solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform extensibility is used throughout the liner, then the liner is simple to manufacture, but it causes pistoning and distal distraction
Solution Approach 1:
The liner incorporates low extensibility strips at specific locations (distal end and other targeted areas) rather than uniformly throughout. These strips are strategically placed to prevent pistoning and distal distraction only where needed, while maintaining normal extensibility in other regions for comfort and knee flexion. This localized application resolves the contradiction by providing differential extensibility properties only where clinically required.
Solution Approach 2:
The liner is divided into distinct functional zones: regions with low extensibility strips and regions without them. The distal end contains strips to prevent pistoning, while other areas may remain unstrengthened or have different strip configurations. This segmentation allows each zone to perform its specific function independently, preventing uniform constraint while addressing localized problems.
2Reliability
If low extensibility strips are added to reduce longitudinal stretch, then pistoning is reduced, but transverse stretch may be compromised
Solution Approach 1:
The low extensibility strips are applied selectively to specific regions (primarily the distal end) rather than uniformly across the entire liner. This localized reinforcement provides longitudinal stability where needed to prevent pistoning, while leaving other areas with full extensibility to accommodate knee flexion and movement. The directional properties of the strips also allow transverse stretch to be preserved while restricting longitudinal movement.
Solution Approach 2:
The liner's extensibility parameters are modified locally by adding low extensibility strips that specifically reduce longitudinal stretch while maintaining or allowing transverse stretch. This selective parameter modification changes the mechanical properties of the liner in a controlled manner, reducing pistoning through longitudinal constraint while preserving the ability to flex the knee through maintained transverse compliance.
3Adaptability or versatility
If custom-made liners are used to address individual needs, then patient-specific requirements are met, but manufacturing cost increases
Solution Approach 1:
The liner system uses modular low extensibility strips that can be independently applied to different regions of a standard liner. This allows customization for different patient needs (distal distraction prevention, pistoning control, localized support) without requiring completely custom-made liners. The strips can be selectively placed based on individual patient requirements, providing adaptability while using standardized components for cost-effective manufacturing.
Solution Approach 2:
Rather than customizing the entire liner for each patient, the solution applies localized low extensibility strips only to the specific regions where support is needed. This allows a standard liner to be adapted to individual patient requirements through selective strip placement, maintaining manufacturing efficiency while achieving patient-specific functionality.
Data Source
AI summary
A prosthetic liner having a lower longitudinal stretch in the distal region than in either the proximal or optional intermediate region. The distal region may stretch anywhere from 0-30% vertically and 10-200% horizontally as compared to the proximal region's vertical stretch of 55-125% and 100-175% horizontally. A variety of stitches may be used at the distal end to implement this lowered longitudinal stretch. The liner also has an interior layer of elastomer gel. The design of this prosthetic liner is primarily to prevent the “pistoning” of the amputee's residual limb within the liner and for comfort over pressure-sensitive areas of the residual limb. The liner also includes the use of a low extensibility material which is adhered to the fabric portion of a prosthetic liner or orthotic liner either internally or externally and limits the longitudinal movement while allowing for transversal movement.