Insulated Pedicle Access System for Nerve Damage Prevention
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Solution Overview
Problem
During minimally invasive spinal surgery, there is a risk of pedicle breach or nerve damage when placing pedicle screws, particularly during initial access, due to the difficulty in maneuvering traditional needles and varying EMG stimulation thresholds among medical instruments.
Innovation Solution
A pedicle access system comprising a cannula, stylet, and T-handle that facilitates easy handling and dynamic pedicle integrity testing by applying a stimulation signal during pilot hole formation, with a conductive elongated shaft and insulation features to prevent shunting of electrical current, allowing for secure and accurate assessment of pedicle integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional needle is used for initial pedicle access, then the procedure can be performed minimally invasively, but the needle is difficult to maneuver and the risk of pedicle breach increases
Solution Approach 1:
The pedicle access system is divided into separate components: a cannula for initial access and positioning, a stylet for pilot hole formation, and a T-handle for manipulation. This segmentation allows each component to be optimized for its specific function, improving both ease of handling and reliability compared to using a single traditional needle.
Solution Approach 2:
The cannula serves as an intermediary device that facilitates safe initial access to the pedicle. It provides a protective conduit that reduces the risk of breaching the pedicle during insertion, while still allowing the stylet to pass through for pilot hole formation. The T-handle acts as another intermediary that improves maneuverability during the procedure.
2Measurement precision
If an electrified needle is used for pedicle integrity testing, then stimulation signals can be applied, but different instruments produce different EMG stimulation thresholds leading to inaccurate assessments
Solution Approach 1:
The system changes the electrical parameters by using a conductive stylet within an insulated cannula. This configuration standardizes the stimulation signal delivery, ensuring consistent EMG thresholds across different procedures and instruments. The insulation on the cannula prevents current leakage, while the conductive stylet provides reliable electrical contact for accurate pedicle integrity assessment.
3Measurement precision
If electrical current is applied during pilot hole formation, then pedicle integrity can be assessed dynamically, but current may shunt through conductive instruments reducing testing accuracy
Solution Approach 1:
The cannula is selectively insulated along its length, with the insulation positioned to prevent current shunting while allowing current delivery at the distal tip where the stylet contacts the pedicle. This local differentiation of electrical properties ensures that stimulation current flows through the intended path (stylet to pedicle) rather than shunting through the cannula, maintaining testing accuracy.
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 reduces the risk of pedicle breach and nerve damage by enabling precise pedicle integrity testing and easy maneuverability, improving the accuracy of pedicle screw placement and reducing the need for revision surgeries.
Implementation Method 1
the elongated shaft may be composed of a conductive material, such as metal
Implementation Method 2
A polymeric coating may be provided on a substantial portion of the exterior surface of the elongated shaft such that the elongated shaft includes an insulated region and an uninsulated region
Implementation Method 3
Traditional EMG monitoring systems may be employed to augment the ability to detect such innervation
Data Source
AI summary
A pedicle access system including a cannula, a stylet, and a removable T-handle. The pedicle access system may be used to percutaneously approach the pedicle, initiate pilot hole formation, and conduct a stimulation signal to the target site for the purposes of performing a pedicle integrity assessment during the pilot hole formation. To do this, the cannula and stylet are locked in combination and inserted through an operating corridor to the pedicle target site, using the T-handle to facilitate easy movement and positioning of the cannula/stylet combination. A stimulation signal may be applied during pilot hole formation to conduct the pedicle integrity assessment. In a significant aspect, the T-handle may be detached from the cannula/stylet combination to facilitate the use of various surgical tools as necessary.