Magnetic Sensor Prosthesis Tracking System
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Solution Overview
Problem
Current methods for detecting aseptic loosening in orthopedic prostheses, such as elbow joints, are inadequate due to low accuracy, high costs, and radiation exposure, limiting early detection and prolonged monitoring capabilities.
Innovation Solution
A system using a permanent magnet and magnetic sensor to measure magnetic field strength, allowing for continuous tracking of relative displacement between the prosthesis and bone, with a processor determining displacement based on magnetic field data, offering improved sensitivity, accuracy, and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If x-ray imaging is used to detect loosening at regular time intervals, then loosening can be detected, but the accuracy is low and radiation exposure occurs
Solution Approach 1:
The patent replaces the mechanical/radiological detection system (x-ray imaging) with a magnetic field-based sensing system. A permanent magnet is attached to the prosthesis and a magnetic sensor is implanted in the bone, eliminating radiation exposure while providing continuous, accurate displacement measurements through magnetic field interactions.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the prosthesis and the detection system. The permanent magnet on the prosthesis generates a magnetic field that is sensed by the magnetic sensor in the bone, allowing indirect measurement of relative displacement without direct mechanical contact or radiation.
2Measurement precision
If RSA technique is used to measure early signs of prosthesis displacement, then high precision measurement is achieved, but it can only be used in a small number of patients and requires prolonged monitoring
Solution Approach 1:
The patent extracts the sensing function from complex external imaging systems (RSA requiring radiologists and specialized equipment) and embeds it directly in the patient's body through a small magnetic sensor. This simplifies the monitoring system while maintaining high measurement precision for displacement detection.
Solution Approach 2:
The implanted magnetic sensor continuously monitors displacement autonomously without requiring external equipment or specialist intervention. The system performs self-measurement of prosthesis migration, eliminating the need for repeated RSA scans and reducing monitoring complexity.
3Measurement precision
If magnetic sensor and permanent magnet system is used for tracking relative displacement, then continuous monitoring with high accuracy is achieved, but the system complexity increases
Solution Approach 1:
The patent combines the magnet and sensor into a simple two-component system where the permanent magnet is attached to the prosthesis and the magnetic sensor is implanted in the bone. This merged system provides continuous displacement monitoring through their magnetic interaction, achieving high accuracy without complex mechanics.
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
Enables accurate, cost-effective, and prolonged monitoring of prosthesis stability, reducing the risk of aseptic loosening by providing precise tracking of relative displacement, thus enhancing the longevity of orthopedic implants.
Implementation Method 1
a permanent magnet fixed relative to the first element; a magnetic sensor fixed relative to the second element, the magnetic sensor configured to measure a magnetic field strength
Data Source
AI summary
A system for tracking relative displacement between a first element and a second element in a structure, the system includes: a permanent magnet fixed relative to the first element; a magnetic sensor fixed relative to the second element, the magnetic sensor configured to measure a magnetic field strength; and a processor configured to determine the relative displacement between the first element and the second element, based on the magnetic field strength measured by the magnetic sensor. This invention has particular applications in e.g. orthopaedic prostheses. A related method includes the steps of measuring, using the magnetic sensor, a magnetic field strength; and determining the relative displacement between the relative displacement between the first element and the second element, based on the magnetic field strength measured by the magnetic sensor.