Heat-Formable Prosthetic Sockets for Precise Residual Limb Fit
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Solution Overview
Problem
The conventional process of making prosthetic sockets is time-consuming, imprecise, costly, and stressful for amputees, often requiring multiple adjustments and materials that are not reimbursed by insurance, leading to suboptimal fit and chronic pain, and existing low-temperature thermoplastics lack the durability needed for weight-bearing applications.
Innovation Solution
Prosthetic sockets are formed directly to the residual limb using proprietary thermoplastic materials that are dry-heated to become pliable and stretchable, eliminating casting and model-making processes, and utilizing a prosthetic liner to protect the limb during socket formation, with injection molding and higher temperature ranges (225° F. to 275° F.) to achieve a precise, durable, and adjustable fit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional casting and model-making processes are used to make prosthetic sockets, then the socket can be customized to fit the residual limb, but the process is time-consuming and requires multiple adjustments
Solution Approach 1:
The patent changes the temperature parameter of the thermoplastic material to achieve pliability (heating to specific temperature range), enabling direct forming over the residual limb. This eliminates multiple adjustment iterations by allowing precise conformability in a single manufacturing step, resolving the contradiction between fit precision and manufacturing time.
Solution Approach 2:
The patent utilizes the phase transition of thermoplastic materials from rigid to pliable state through heating, allowing the socket material to conform to the residual limb's exact shape during forming, then revert to rigid state for structural integrity. This single-phase-transition approach achieves precise fit without requiring multiple adjustment visits.
2Strength
If conventional high-temperature thermoplastics and fiberglass are used, then the socket has sufficient durability for weight-bearing, but the materials are toxic and require complex ventilation and disposal procedures
Solution Approach 1:
The patent employs composite materials consisting of thermoplastic polymers reinforced with fibers (such as carbon fiber, glass fiber, or organic fibers). This composite structure provides the necessary mechanical strength and durability for weight-bearing applications while avoiding the toxic properties of conventional fiberglass and resin systems, eliminating ventilation requirements and simplifying disposal.
Solution Approach 2:
The patent utilizes thermoplastic materials that can be easily formed and adjusted, allowing for cost-effective manufacturing. The materials are designed to be durable enough for the intended application lifespan but can be disposed of or replaced more easily than conventional fiberglass sockets, reducing long-term environmental and health concerns.
3Manufacturing precision
If the entire model is reduced in circumference to achieve a tight fit, then the socket fits precisely, but sensitive areas of the residual limb experience excessive pressure and pain
Solution Approach 1:
The patent applies local quality by creating varying degrees of circumferential reduction at different locations along the residual limb. The thermoplastic material is selectively heated and formed to provide tight fit in non-sensitive areas while maintaining larger circumference or creating relief areas over sensitive regions such as bone prominences and scar tissue, distributing pressure appropriately and eliminating pain while maintaining overall precision.
4Adaptability or versatility
If abrasive files and sand paper are used to adjust the model shape, then the socket can be customized to reduce contact with sensitive areas, but the process is imprecise and time-consuming
Solution Approach 1:
The patent replaces the mechanical abrasion process (files and sand paper) with a thermal-forming process. The thermoplastic material is heated to become pliable, then directly formed over the residual limb or mold to achieve the desired shape and pressure distribution. This substitution provides precise customization capability while eliminating the imprecise and time-consuming nature of manual abrasion methods.
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
This method significantly reduces the time and materials required, allows for quick adjustments, and provides a durable, lightweight socket that can be reformed as the residual limb changes, improving comfort and function while reducing equipment and travel needs.
Implementation Method 1
when heated to between about 225° F. and about 275° F.
Implementation Method 2
the conical cup and the lower portion, when heated to between about 225° F. and about 275° F. have a working time of between about five minutes and about 15 minutes before hardening
Implementation Method 3
before hardening as room temperature is approached
Data Source
AI summary
The present disclosure is directed to prosthetic limb sockets that couple prosthetic limbs to residual limbs. The sockets include a conical cup sized to engage and couple to the residual limb, and a base to secure the socket to the prosthetic limb. The sockets are direct heat-formable onto the residual limb, such that they can be heated and formed as they are secured to the residual limb.