Passive Resonant Circuit Strain Sensor for Spinal Fusion Monitoring
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Solution Overview
Problem
Current methods for monitoring spinal fusion after lumbar surgery are inadequate, as they struggle to determine the onset of fusion, leading to prolonged immobilization and muscle atrophy due to uncertain load-sharing changes in spinal implants.
Innovation Solution
A strain-sensing apparatus with a passive electrical resonant circuit, such as an LC resonant circuit, is mounted on the implant, which generates a frequency signal indicative of strain when electromagnetically coupled, allowing for wireless monitoring of the implant's strain and load-sharing changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to monitor spinal fusion, then the monitoring process is simple, but the measurement precision is insufficient to determine the onset of fusion
Solution Approach 1:
The patent replaces conventional mechanical or radiographic monitoring methods with a strain sensing system that uses electrical/electronic sensors to measure strain on the implant. The sensor assembly includes strain gauges or similar transducers that convert mechanical strain into electrical signals, enabling precise quantitative measurement of fusion progress without the limitations of traditional imaging methods.
Solution Approach 2:
The patent introduces a sensor assembly as an intermediary element attached to the spinal implant. This sensor assembly acts as a mediator between the implant and the monitoring system, transferring strain information from the implant to external monitoring equipment through electrical signals, thereby enabling indirect but precise measurement of fusion status.
2Reliability
If prolonged immobilization is applied to ensure fusion, then the reliability of fusion is improved, but the loss of time and muscle atrophy increase
Solution Approach 1:
The patent implements a feedback mechanism where the sensor assembly continuously monitors strain on the implant and provides real-time data about fusion progress. This feedback allows clinicians to make informed decisions about when fusion has sufficient strength to reduce immobilization, optimizing the balance between fusion reliability and minimizing immobilization duration to prevent muscle atrophy.
Solution Approach 2:
The patent enables dynamic adjustment of immobilization protocols based on actual fusion progress rather than fixed time schedules. As the fusion matures and strain decreases, the immobilization can be progressively reduced, allowing the system to adapt to the changing mechanical state of the fusion site and optimize both safety and patient recovery.
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 non-invasive, real-time monitoring of spinal fusion progress, reducing the need for prolonged immobilization and minimizing muscle atrophy by providing quantitative data on bone fusion and implant stress.
Implementation Method 1
each sensor assembly can comprise a passive electrical resonant circuit configured to be selectively electromagnetically coupled to an ex-vivo source of RF energy
Implementation Method 2
a passive electrical resonant circuit that is configured to be selectively electromagnetically coupled to an ex-vivo source of RF energy
Data Source
AI summary
This application relates to an apparatus and system for sensing strain on a portion of an implant positioned in a living being. In one aspect, the apparatus has at least one sensor assembly that can be mountable thereon a portion of the implant and that has a passive electrical resonant circuit that can be configured to be selectively electromagnetically coupled to an ex-vivo source of RF energy. Each sensor assembly, in response to the electromagnetic coupling, can be configured to generate an output signal characterized by a frequency that is dependent upon urged movement of a portion of the passive electrical resonant circuit and is indicative of strain applied thereon a portion of the respective sensor assembly.