Spinal Set Screw Load Sensing Assembly
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Solution Overview
Problem
Conventional load assemblies and screw assemblies for spinal implants are unable to sense and wirelessly transmit the connection force between a longitudinal rod and a pedicle screw, and they cannot continuously monitor and maintain a secure connection over long time frames.
Innovation Solution
A load sensing assembly for spinal implants that includes a set screw with integrated electronic components and an antenna, capable of sensing the force between the set screw and the longitudinal member and wirelessly transmitting this data for continuous monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional load assemblies and screw assemblies are used for spinal implants, then the structure is simple and easy to manufacture, but they are unable to sense and wirelessly transmit the connection force between the longitudinal rod and pedicle screw
Solution Approach 1:
The patent combines multiple functions into the set screw assembly: the set screw serves both as a mechanical fastener to secure the longitudinal rod to the pedicle screw, and as a housing for electronic sensing components. The body of the set screw contains an internal cavity that houses the sensor, antenna, and electronic circuitry, merging mechanical fastening with wireless load sensing capabilities into a single integrated component.
Solution Approach 2:
The set screw assembly is designed to perform multiple functions simultaneously: (1) mechanical fastening of the longitudinal rod to the pedicle screw, (2) sensing the connection force through integrated sensors, (3) wirelessly transmitting load data via an antenna, and (4) providing continuous monitoring over extended periods. This multi-functional design resolves the contradiction by adding sensing capabilities without requiring separate additional components.
2Duration of action of moving object
If conventional screw assemblies are used, then the device is easy to operate and install, but they cannot continuously monitor and maintain a secure connection on relatively long time frames
Solution Approach 1:
The load sensing assembly is designed to autonomously perform monitoring functions without requiring external intervention. The sensor continuously measures connection forces, the electronic circuitry processes the data, and the antenna wirelessly transmits information to external receivers. This self-service capability enables continuous monitoring over extended periods while maintaining ease of operation during installation, as the system activates automatically upon implantation.
Solution Approach 2:
The patent replaces traditional mechanical load measurement methods with electronic sensing and wireless communication systems. Instead of requiring physical disassembly or direct mechanical measurement, the electronic sensor and antenna system provides continuous remote monitoring, extending the duration of action while simplifying long-term operation through non-invasive data collection.
3Reliability
If an integrated load sensing system with antenna and electronics is incorporated into the set screw, then continuous wireless monitoring is enabled, but the manufacturing complexity increases
Solution Approach 1:
The patent employs a nested structure where the sensor, electronic circuitry, and antenna are housed within the internal cavity of the set screw body. The sensor is positioned to directly contact or sense the interface between the longitudinal rod and pedicle screw, while the antenna and electronics are nested within the same housing. This nested arrangement integrates multiple components into a compact configuration that maintains manufacturing feasibility while enabling reliable continuous monitoring of connection integrity.
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 enables continuous monitoring of the connection force between the longitudinal rod and the pedicle screw, ensuring a secure and stable implantation over extended periods.
Implementation Method 1
the antenna is configured to transmit information received from the at least one sensor to an external device
Data Source
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Figure 3A
AI summary
A load sensing assembly for a spinal implant includes a set screw (50) having a drive interface (52), a lower cavity (54a) for receiving a cover (55), the cover including a protrusion (55a) that may engage with an anchoring member. The load sensing assembly further includes an antenna (300), and at least one sensor having an integrated circuit in communication with the antenna. In some embodiments, the integrated circuit is positioned within a sealed cavity of the set screw. In some embodiments, the antenna comprises a ferrite core (412) and a plurality of windings (416) that are oriented laterally with respect to a longitudinal axis of the set screw. In some embodiments, the sealed cavity of the set screw is hermitically sealed, and the antenna may be mechanically isolated by a bellows (440) or cylindrical can structure.