Silicone Cladding for Prosthetic Limbs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional leg prostheses face issues with structural complexity, visibility when sitting, heat transfer from sunlight, and discomfort due to the exposed profile between the thigh and lower leg parts, which affects the cosmetic and thermal insulation aspects.
Innovation Solution
A flexible silicone cladding surrounds the thigh part and stump end, with varying Shore hardnesses to secure trousers and prevent heat transfer, ensuring the prosthesis is cosmetically and thermally insulated, allowing for unhindered movement and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a rigid protective device or cover is used between the thigh part and lower leg part, then the cosmetic appearance and thermal insulation are improved, but the structural complexity and difficulty of retrofitting increase
Solution Approach 1:
The patent applies a flexible silicone cladding instead of rigid protective devices. The cladding is made of elastomeric material that can conform to the body contours while providing thermal insulation and cosmetic coverage. This flexible shell approach eliminates the need for complex rigid structures while achieving the desired protective functions.
Solution Approach 2:
The patent utilizes the elastomeric properties of silicone material, which can change its physical parameters (flexibility, hardness) based on temperature and deformation. The material transitions between soft and rigid states to accommodate different functional requirements - soft for comfort and flexibility, rigid enough for structural support and insulation.
2Shape
If a rigid cover is used to prevent trouser collapse, then the cosmetic appearance is improved, but the ease of movement and flexibility are reduced
Solution Approach 1:
The flexible silicone cladding maintains the cosmetic appearance of the prosthetic limb when the user sits down, preventing trouser collapse, while simultaneously allowing full range of motion. The elastomeric material stretches and deforms with body movements, providing both aesthetic coverage and functional flexibility.
Solution Approach 2:
The cladding is designed to be dynamic rather than static, adapting its shape and rigidity based on the movement state. During movement, the material becomes more flexible to accommodate joint rotation; during static positions like sitting, it maintains its shape for cosmetic purposes.
3Shape
If the cladding material is made uniformly hard to prevent trouser collapse, then the cosmetic appearance is improved, but the comfort and movement freedom in the knee area are reduced
Solution Approach 1:
The cladding features non-uniform hardness distribution with different Shore hardness values in different regions. The thigh area has higher hardness for structural support and trouser prevention, while the knee area has lower hardness for comfort and movement freedom. This local differentiation resolves the contradiction between cosmetic appearance and operational comfort.
Solution Approach 2:
The silicone material composition is varied across different regions of the cladding, creating gradients in physical properties. The material parameters (hardness, elasticity) are changed locally to match the functional requirements of each anatomical region, providing both cosmetic appearance and comfort.
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 effectively prevents trouser collapse and heat transfer, maintaining comfort and functionality while enhancing the cosmetic appearance of the prosthesis, particularly in the knee joint area.
Implementation Method 1
the silicone material has different Shore hardnesses such that the material in the knee area is softer than the material in the stump area
Implementation Method 2
it is ensured that the cladding prevents any direct heat influence on the prosthesis part and thus on the bone and stump
Data Source
Figure 1
Figure 2~3
AI summary
The leg prosthesis (1) has a lower leg part (4), where a foot part is arranged at the lower leg part. An upper leg part (2) is hinged at the lower leg part in a knee-joint shape. The upper leg part is provided with a covering (8) on a silicon base, where the covering is conically tapered from a butt end (5) of an upper leg front side to a knee joint (3). The covering surrounds the upper leg part and the butt end of the upper leg front side based on leg- and knee joint sides, where the covering is open at an upper leg rear side.