Set Screw Load Sensing for Spinal Implant Force Monitoring
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Solution Overview
Problem
Monitoring the connection force and maintaining the integrity of longitudinal members and pedicle screws in spinal implant devices is challenging, as existing technologies lack effective methods to ensure proper force distribution and measurement during and after implantation.
Innovation Solution
A load sensing assembly with an integrated circuit, strain gauge, and antenna is used, which includes memory for storing measurements and transmitting data via RFID or NFC, allowing for real-time monitoring of forces between anchoring members and longitudinal members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional screw assemblies are used to connect longitudinal members to vertebral members, then the mechanical connection is simple and reliable, but the connection force and integrity cannot be monitored during and after implantation
Solution Approach 1:
The electronics component with integrated circuit, strain gauge, and antenna is nested within the central opening of the set screw, allowing the sensing assembly to be integrated into the existing screw structure without adding external components that would complicate implantation
Solution Approach 2:
The strain gauge replaces traditional mechanical force measurement methods with an electrical sensing system that can transmit data wirelessly, enabling force monitoring without mechanical linkages or external wiring
2Measurement precision
If sensors and electronics are integrated into the set screw, then force monitoring capability is achieved, but the device complexity increases
Solution Approach 1:
The set screw serves multiple functions: it provides mechanical fastening through thread engagement, houses the electronics component within its central opening, and enables wireless force monitoring through the integrated strain gauge and antenna system
Solution Approach 2:
The patent combines the mechanical fastening function of the set screw with the sensing and communication functions of the electronics component, strain gauge, and antenna into a single integrated assembly, reducing the number of separate components
3Adaptability or versatility
If a central opening in the set screw is used to house electronics, then the sensing assembly can be integrated, but the structural strength of the screw may be compromised
Solution Approach 1:
The central opening is positioned in a specific location within the set screw structure where it provides necessary access for the electronics component while maintaining adequate material distribution to preserve the overall structural strength and threading integrity of the screw
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 and continuous monitoring of forces, ensuring proper placement and maintaining the necessary force levels, thereby enhancing the stability and effectiveness of spinal implant procedures.
Implementation Method 1
a strain gauge located within the channel, where the strain gauge is configured to measure a force between the anchoring member and the longitudinal member
Implementation Method 2
an antenna, an integrated circuit in communication with the antenna and positioned within the central opening of the set screw... transmit the one or more measurements to a reader when the reader is in proximity to the integrated circuit
Data Source
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AI summary
A load sensing assembly for a spinal implant includes a set screw having a central opening that extends from a first end of the set screw toward a second end of the set screw. The second end of the set screw is configured to engage with an anchoring member. The load sensing assembly includes an antenna, an integrated circuit in communication with the antenna, where the integrated circuit is positioned within the central opening of the set screw, and a strain gauge in connection with the integrated circuit. The strain gauge is located within the central opening of the set screw in proximity to the second end of the set screw.