Inflatable Limb Liner Gap Filling via Pneumatic Hub
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Solution Overview
Problem
Existing air control systems for prosthetic limbs fail to effectively manage shape changes in residual limbs due to physiological changes, leading to gaps between the limb liner and the prosthetic socket, causing discomfort and instability.
Innovation Solution
An air-controlled interface system with an inflatable interface and hub assembly that allows for adjustable air flow to fill gaps between the limb liner and the prosthetic socket, using an air conduit and inflatable gap with optional open cell foam for self-inflation, and a hub assembly with mechanical fasteners to maintain the connector pin's functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a gel liner or multiple layers of knitted socks are used to fill gaps, then the gaps between the limb liner and prosthesis are filled, but the padding adds thickness to the entire limb liner causing segments that fit properly to become tight
Solution Approach 1:
The patent uses an inflatable liner system with an air pump and bladder to dynamically adjust the interface between the residual limb and prosthesis. Air can be pumped into the bladder to inflate it and fill gaps, or deflated to reduce pressure. This pneumatic system allows for adjustable pressure distribution without adding permanent thickness to the liner, resolving the contradiction between gap filling and comfort.
Solution Approach 2:
The inflatable liner system transforms a static liner into a dynamic interface that can adapt to changes in residual limb size and shape. The liner can be inflated or deflated as needed to maintain proper fit and comfort, allowing the system to respond to physiological changes without requiring permanent thickening of the liner material.
2Shape
If fabric-based liner socks are worn to fill gaps, then gaps are filled, but the liner sock becomes compressed at points of contact while remaining less compressed in areas of gaps, creating uneven pressure distribution
Solution Approach 1:
The inflatable bladder system provides uniform pressure distribution through pneumatic inflation. When air is pumped into the bladder, the pressure is transmitted evenly throughout the liner material, ensuring consistent pressure distribution across the entire interface rather than the localized compression seen with fabric socks. The system can be deflated to reduce pressure in specific areas as needed.
3Adaptability or versatility
If the residual limb undergoes physiological changes causing size and contour variations, then the limb liner configuration changes, but the socket remains fixed, creating gaps and mismatch in shape
Solution Approach 1:
The inflatable liner system provides adaptability to physiological changes by allowing dynamic adjustment of the liner's volume and pressure. As the residual limb changes size or contour, the user can inflate or deflate the bladder to maintain proper contact and fit, enabling the system to adapt to limb changes without requiring a complex removable liner system.
Solution Approach 2:
The system changes the physical parameters of the liner by adjusting air pressure and volume within the bladder. This allows the liner to expand or contract to match changes in residual limb dimensions, providing adaptability through parameter adjustment rather than through complex mechanical reconfiguration.
4Ease of operation
If gel liners are made thin to minimize discomfort, then comfort is improved, but they cannot effectively fill gaps when larger gaps exist
Solution Approach 1:
The inflatable bladder system overcomes the thickness limitation of gel liners by using pneumatic pressure to expand the liner material. When gaps are present, air can be pumped into the bladder to inflate it and fill the gaps effectively. When comfort is the primary concern, the system can be deflated to minimize pressure on sensitive areas. This provides both gap filling capability and comfort control without requiring the liner to be permanently thick.
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 ensures a secure and comfortable fit by adjusting to shape changes in the residual limb, maintaining the connector pin's interconnection and providing customizable support and pressure adjustment.
Implementation Method 1
An inflatable interface (22) is provided within the socket (16). The inflatable interface (22) has an exterior layer (26) and an interior layer (28). An inflatable gap (27) exists between the exterior layer (26) and the interior layer (28). The inflatable gap (27) can selectively expand and contract depending upon the air pressure within the gap (27).
Implementation Method 2
In the prior art, several inflatable liners have been invented for use between amputated limbs and prostheses. The inflatable liners can be selectively inflated to provide an adjustable interface between the residual limb and the prosthesis.
Data Source
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AI summary
A system for joining a limb liner (12) to a prosthesis (18). The prosthesis (18) has a socket(16) that is joined to the remainder of the prosthesis (18) using a hub assembly (34). The hub assembly (34) includes a first hub (32) and a second hub (33). The first hub (32) is disposed within the interior of the socket (16). The second hub (33)is disposed outside the interior of the socket (16). An air conduit (36) extends through the hub assembly (34) that enables air to be drawn into the socket (16) and/or vented from the socket (16). An inflatable interface (22) is disposed within the socket (16). The inflatable interface (22) receives air through the air conduit (36) in the hub assembly (34). The inflatable interface (22) is capable of filling any gaps that may exist between a limb liner (12) being worn by an amputee and the socket (16).