Prosthetic Liner With Inelastic Tensile Elements

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Solution Overview

Problem

The production of prosthesis liners is complex and expensive due to the large number of textile elements that need to be sewn together, leading to potential pressure points and reduced wearing comfort.

Innovation Solution

Incorporating tension elements made of inelastic materials into the textile layer, particularly in the connection area, to reduce elasticity and distribute tensile forces more evenly, thereby simplifying production and enhancing comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple textile elements are sewn together to create the liner, then the liner can provide necessary elasticity and fit, but the production becomes complex and expensive, and seams create pressure points

Engineering Contradiction:
Improveliner fit and elasticityVSAvoidproduction complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges multiple separate textile elements into a single continuous textile layer. Instead of sewing together multiple elastic panels to achieve the desired fit and elasticity, the invention uses one continuous layer that is stretched and molded during the injection molding process to conform to the stump's shape, thereby eliminating seams and reducing production complexity while maintaining adaptability

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs a thin, flexible textile layer that is integrated into the injection-molded prosthetic liner. This textile layer acts as a flexible membrane that provides the necessary elasticity and conformability to the user's stump while being formed as a single piece during manufacturing, avoiding the need to assemble multiple components

Inventive Principle:
Principle #30Flexible shells and thin films

2Adaptability or versatility

If multiple textile elements are sewn together to create the liner, then the liner can provide necessary elasticity and fit, but the production cost increases

Engineering Contradiction:
Improveliner fit and elasticityVSAvoidproduction cost
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent combines multiple textile components into a single integrated textile layer that is incorporated during the injection molding process. This eliminates the need for separate procurement, storage, and assembly of multiple textile elements, thereby reducing production costs while maintaining the liner's elasticity and adaptive fit

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The textile layer is designed to be self-integrating during the injection molding process. The textile is positioned in the mold cavity and the liquid plastic material flows around and bonds to it, automatically creating the finished liner structure without requiring additional assembly operations or manual sewing, thus reducing labor costs and simplifying manufacturing

Inventive Principle:
Principle #25Self-service

3Ease of operation

If elastic material is used throughout the liner, then the liner can be easily applied and fit different stump shapes, but tensile forces concentrate on the distal area causing milking effect

Engineering Contradiction:
Improveliner application easeVSAvoidmilking effect on stump
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies different material properties to different regions of the liner. The textile layer has varying knit structures in different zones: a first knit structure in the distal region with different elasticity characteristics than a second knit structure in other regions. This local variation in textile structure allows the distal area to better manage tensile forces and reduce the milking effect while maintaining overall ease of application and fit

Inventive Principle:
Principle #3Local quality

4Reliability

If fastening elements are used to secure the liner to the socket, then the connection is secure, but all tensile forces act on the distal area placing high mechanical load there

Engineering Contradiction:
Improveconnection securityVSAvoidmechanical load on distal area
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent creates a localized connection area with modified textile properties at the distal end of the liner. This connection area has reduced elasticity in the longitudinal direction compared to other regions, allowing it to better withstand and distribute the mechanical loads from fastening elements while maintaining secure connection to the prosthetic socket

Inventive Principle:
Principle #3Local quality

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 solution reduces the complexity and cost of producing prosthesis liners while improving wearing comfort by evenly distributing tensile forces and reducing pressure on the amputation stump.

Implementation Method 1

the textile layer in a section extending proximally from the connection area has at least one tensile element by which the elasticity of the textile layer in the textile direction of the base body is reduced and which has fibers and/or threads made of an inelastic material

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3886770B1Prosthetic liner
Publication Date: 2023.07.19 OTTOBOCK SE & CO KGAA
  • EP3886770B1 patent drawingFigure 1~2
  • EP3886770B1 patent drawingFigure 3~4
  • EP3886770B1 patent drawingFigure 5

AI summary

The invention relates to a prosthesis liner (2) with • - a main body made of an elastic liner material, which has • o an open proximal end, • o a closed distal end opposite the proximal end and • o a longitudinal extent running from the proximal end to the distal end, • - a bi-elastic textile layer which is arranged on or in the liner material, and • - a connection region (18) which is arranged and configured to be connected to a prosthesis socket, wherein the textile layer, in a portion extending proximally from the connection region, has at least one tensioning element (8), by which the elasticity of the textile layer is reduced in the longitudinal direction of the main body.