Spinal Rod Receiver With Strain Sensing for Connection Integrity
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Solution Overview
Problem
Conventional load assemblies and screw assemblies used in spinal implants are unable to monitor and maintain a secure connection between a longitudinal member and a pedicle screw, as they lack the capability to sense and transmit connection force, especially over extended periods.
Innovation Solution
The implementation of a load sensing spinal implant with a receiver that includes a U-shaped cavity for supporting a longitudinal rod and set screw, integrated strain gauges to detect localized forces, and antennas to transmit data using Medical Implant Communication System (MICS) technology, ensuring continuous monitoring of connection integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional load assemblies and screw assemblies are used to connect longitudinal member to pedicle screw, then the connection structure is simple and easy to manufacture, but the capability to sense and transmit connection force is lost
Solution Approach 1:
The patent combines multiple functions into the receiver component: it serves as both the mechanical connector for the pedicle screw and longitudinal rod, and as the housing for the strain gauge sensor and electronics. This integration allows force sensing capability to be added without requiring separate sensing components, thereby reducing overall system complexity while enabling measurement.
Solution Approach 2:
The strain gauge acts as an intermediary element that converts mechanical deformation (caused by connection forces) into electrical signals that can be transmitted and monitored. This mediator enables the connection force to be sensed and communicated without requiring direct mechanical measurement methods.
2Reliability
If conventional screw assemblies are used without sensing capabilities, then the device is reliable and simple, but the ability to continuously monitor connection integrity over time is lost
Solution Approach 1:
The strain gauge provides continuous feedback on the connection force between the longitudinal rod and pedicle screw. This feedback mechanism allows real-time monitoring of connection integrity, enabling detection of loosening or failure conditions without requiring complex additional monitoring systems.
Solution Approach 2:
The receiver structure is designed to inherently support the sensing function through its geometry and material properties. The strain gauge is integrated into the receiver's load-bearing path, allowing the existing structural components to serve dual purposes: mechanical connection and force sensing, rather than requiring separate dedicated sensing structures.
3Duration of action of moving object
If strain gauges and electronics are integrated into the receiver, then continuous monitoring of connection force is enabled, but the manufacturing complexity and precision requirements increase
Solution Approach 1:
The receiver is designed with pre-configured mounting features and integrated sensor pathways during the manufacturing process. The strain gauge is positioned and secured within the receiver structure before final assembly, ensuring proper alignment and reducing the need for post-manufacturing adjustments or high-precision field installation.
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 continuous monitoring and maintenance of secure connections between spinal implant components, providing real-time data on connection forces to ensure proper placement and stability, thereby preventing construct failure and enhancing treatment efficacy.
Implementation Method 1
at least one strain gauge configured to detect a localized force experienced by the receiver
Implementation Method 2
at least one antenna configured to transmit information received from the at least one strain gauge to an external device
Data Source
AI summary
A digital pedicle screw assembly may be installed inside of the body of a patient and be configured to sense various attributes of the assembly and the patient. Embodiments may include a receiver having a U-shaped cavity for supporting a longitudinal rod and set screw therein. The receiver may include a lower cavity configured to couple to a pedicle screw and a side portion integrally connected to the receiver and including a housing defining a sealed cavity for supporting a microelectronics assembly and a battery therein. Embodiments may include at least one antenna attached to an outside of the housing and being in electrical communication with the microelectronics assembly, and at least one strain gauge configured to detect a localized force experienced by the receiver and being in electrical communication with the microelectronics assembly.