Conductive Stylet for Pedicle Integrity Assessment
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Solution Overview
Problem
Current spinal surgery techniques lack a reliable and intra-operative method for accurately assessing pedicle integrity, which is crucial for preventing damage to neural structures during pedicle screw placement.
Innovation Solution
A surgical tool system comprising a conductive stylet with a distal end advanceable into bone, a handle assembly, and an insulative cannula assembly, which allows for pedicle integrity assessments by transmitting an electrical current to determine if the pedicle wall is breached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging methods are used to confirm screw placement, then visualization of anatomy is provided, but neural integrity cannot be assessed and pedicle breaches cannot be detected
Solution Approach 1:
The patent combines the stylet (used for establishing trajectory) with electrical stimulation capability and visual indication system. The stylet hub integrates electrical contacts that can deliver stimulation signals, and includes visual indicators (windows, markers) to show stimulation delivery status. This merging allows pedicle integrity assessment to be performed using the same tool already present in the surgical workflow, rather than requiring separate complex assessment devices.
Solution Approach 2:
The stylet is designed to serve multiple functions: (1) establishing the pedicle screw trajectory, (2) delivering electrical stimulation signals to assess pedicle integrity, and (3) providing visual feedback on stimulation delivery. This multi-functionality eliminates the need for separate specialized tools for each task, reducing overall device complexity while improving assessment capability.
2Reliability
If electrical pedicle testing is performed to detect malpositioned screws, then immediate repositioning is enabled, but the surgical workflow becomes more complex
Solution Approach 1:
The stylet is equipped with electrical stimulation capability and visual indicators before the actual screw placement. The surgeon can perform pedicle integrity assessment during the trajectory establishment phase, before committing to final screw placement. This preliminary assessment allows potential issues to be detected and corrected early, simplifying the overall workflow by preventing the need for complex post-placement corrections.
Solution Approach 2:
The stylet hub includes visual indicators (windows, markers) that provide immediate feedback to the surgeon about whether electrical stimulation is being delivered and what the response is. This real-time feedback mechanism simplifies the operation by making the electrical pedicle testing intuitive and easy to interpret, eliminating the need for complex monitoring equipment or specialized training.
3Measurement precision
If a conductive stylet hub is used to transmit electrical current, then pedicle integrity can be assessed, but the handle integrity may be compromised
Solution Approach 1:
The stylet hub acts as an intermediary component between the handle and the stylet. It provides the electrical conduction pathway for stimulation while being mechanically connected to the handle through a non-conductive or insulated connection. This intermediary structure allows electrical current transmission without compromising the mechanical strength and integrity of the handle assembly.
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 system enables immediate and accurate detection of pedicle breaches, allowing for immediate repositioning of screws and reducing the risk of neural damage during spinal surgery.
Implementation Method 1
Electrical pedicle testing utilizes the insulating characteristics of bone (specifically, that of the walls of the pedicle) and the conductivity of the exiting nerve roots themselves. If a wall of the pedicle is breached, a stimulation signal applied to the pedicle screw and/or the pilot hole will cause the various muscle groups coupled to the exiting nerve roots to contract.
Data Source
AI summary
A surgical system may include a conductive stylet with a distal end advanceable into bone material and a proximal end coupled to a stylet hub. A handle is non-removably attached to the stylet hub, and removably attachable to an insulative cannula hub. The cannula hub is non-removably attached to a conductive cannula that surrounds the stylet when the handle is attached to the proximal end of the insulative cannula hub. An outer insulative sheath is slideably engaged to insulative cannula hub, and has a radio-opaque distal tip. An electrical signal source may be applied to the stylet hub to conduct a pedicle integrity assessment. The handle and stylet may be removed from the cannula assembly, leaving the cannula assembly in place at the surgical site.