Prosthetic Limb Rotation Control via Bone-Embedded Magnet
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Solution Overview
Problem
Current prosthetic limb rotation control methods, such as osseointegration and artificial epicondyles, are cumbersome, prone to infections, and lack proprioceptive feedback, making them inefficient and unnatural for amputees, especially for lower limb prostheses which lack adaptive control mechanisms.
Innovation Solution
A motorized prosthetic limb system that uses a permanent magnet attached to the residual bone with magnetic sensors to detect rotation and a microprocessor-controlled motor to instantaneously convert residual bone rotation into prosthetic limb rotation, maintaining proprioceptive awareness and allowing for natural movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If osseointegration or artificial epicondyles are used to physically couple residual bone to prosthesis, then proprioceptive feedback is preserved, but risk of infection and skin breakdown increases
Solution Approach 1:
The patent introduces magnetic field interaction as an intermediary mechanism between the residual bone and prosthesis. A magnet embedded in the residual bone interacts with a magnetic sensor in the prosthesis, enabling rotation control without direct physical penetration of the skin. This mediator approach preserves proprioceptive feedback through magnetic coupling while eliminating the infection risks associated with skeletal implants that penetrate the skin.
2Strength
If skeletal implants are used for rotation control, then direct bone-to-prosthesis connection is achieved, but surgical complexity and integration time increase
Solution Approach 1:
The patent replaces the mechanical implant system with a magnetic field-based system. Instead of using titanium bolts or epicondyle implants that require complex surgical procedures for integration, the invention uses a magnet embedded in the residual bone that interacts wirelessly with a magnetic sensor in the prosthesis. This substitution maintains strong connection for rotation control while dramatically reducing surgical complexity and integration time.
3Ease of operation
If body-powered or myoelectric control is used, then active rotation control is achieved, but proprioceptive awareness is lost and cognitive burden increases
Solution Approach 1:
The patent enables the residual bone itself to control the prosthesis rotation through its natural movement. The magnet embedded in the bone moves with the bone's rotation, and this movement is detected by the magnetic sensor to automatically control prosthesis rotation. This self-service approach eliminates the need for external muscle control systems, preserving proprioceptive awareness while providing intuitive active control.
4Adaptability or versatility
If passive femoral rotators are used, then lower limb rotation is provided, but control is manual and requires stable objects for manipulation
Solution Approach 1:
The patent replaces manual mechanical control of passive rotators with a magnetic field-based detection system. Instead of requiring users to manually manipulate devices against stable objects, the invention uses a magnetic sensor to detect the rotation of a magnet embedded in the residual bone and automatically controls prosthesis rotation. This substitution provides rotation capability while enabling intuitive, hands-free control that does not require external stable objects.
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 solution provides improved rotational control with reduced cognitive burden, minimizing the risk of infections and surgical complications while enabling accurate and natural rotation of prosthetic limbs, and can be integrated with other control sources for enhanced functionality.
Implementation Method 1
A permanent magnet having a magnetic field is attached adjacent to the distal end of the rigid bone
Data Source
AI summary
A method and apparatus for improving the control of prosthetic limb rotation in amputees in which a permanent magnet is implanted into the distal end of a residual bone and the bone rotation is sensed from movement of the magnetic field of the magnet and used to effect corresponding rotation of the prosthetic limb.