Break-Off Set Screw With Embedded Load Sensing for Spinal Implants
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Solution Overview
Problem
Existing technologies face challenges in monitoring and maintaining the connection force between longitudinal members and pedicle screws or other connectors in spinal implants, making it difficult to ensure proper or acceptable force is maintained during and after implantation.
Innovation Solution
A load sensing assembly for spinal implants is introduced, featuring a set screw with a central opening containing an integrated circuit, antenna, and strain gauge, which measures the force between the set screw and longitudinal member, and can transmit data to a reader using RFID or NFC technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a set screw is used to secure the connection of a longitudinal member and a pedicle screw, then the connection is secured, but the connection force and integrity cannot be monitored
Solution Approach 1:
The patent replaces the purely mechanical set screw connection system with an integrated sensing system that includes strain gauges, antennas, and integrated circuits. The strain gauges detect mechanical force physically, but this mechanical measurement is converted into electrical signals that can be transmitted wirelessly via RFID or NFC, substituting the need for direct mechanical monitoring with an electronic information system.
Solution Approach 2:
The patent introduces an intermediary sensing system between the set screw and the longitudinal member. The strain gauge acts as an intermediary that indirectly measures the connection force by detecting strain on the set screw, and this information is then transmitted through the integrated circuit and antenna to external monitoring devices, allowing remote monitoring without direct mechanical intervention.
2Measurement precision
If an integrated circuit and strain gauge are positioned within the central opening of the set screw, then real-time monitoring is enabled, but the device complexity increases
Solution Approach 1:
The patent merges multiple functional components into a single integrated set screw assembly. The strain gauge, integrated circuit, and antenna are all positioned within the central opening of the set screw, combining sensing, processing, and communication functions into one unified component that attaches to the longitudinal member without requiring separate mounting structures.
Solution Approach 2:
The set screw is designed with multi-functionality: it serves as both the mechanical fastening element and the mounting platform for the sensing system. The central opening of the set screw universally accommodates the integrated circuit and antenna, allowing the same component to perform both structural and sensing functions simultaneously.
3Ease of operation
If the set screw is designed as a break-off type with two heads, then proper torque application is facilitated, but the manufacturing complexity increases
Solution Approach 1:
The set screw is segmented into two distinct head portions: a first head with a first opening for torque application during installation, and a second head with a second opening for torque application after the break-off point. This segmentation allows different tool access points at different stages of the process, facilitating proper torque application while enabling the break-off mechanism that removes the installation head.
Solution Approach 2:
The break-off point is pre-designed into the set screw structure during manufacturing. The first head is intentionally created as a temporary component that will be removed after serving its preliminary purpose of enabling torque application during installation. This preliminary action facilitates proper installation torque application while the break-off mechanism automatically removes the first head after the set screw is properly tightened.
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
The load sensing assembly provides real-time monitoring of the connection force, ensuring proper placement and maintenance of spinal implants, allowing for immediate adjustments and reducing the risk of loosening or failure.
Implementation Method 1
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... the strain gauge may be configured to measure a force between the set screw and a longitudinal member
Implementation Method 2
The integrated circuit may include one or more of the following radio frequency identification (RFID) chip, or a near-field communication (NFC) chip... transmit the one or more measurements to a reader when the reader is in proximity to the integrated circuit
Data Source
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.