Cannula Electrode Assembly for Nerve Ablation Positioning

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Solution Overview

Problem

Existing medical assemblies for nerve ablation procedures face challenges in precisely repositioning the electrode after it is removed and reinserted, leading to increased procedure time due to difficulties in maintaining the same distal extension of the electrode during the ablation step.

Innovation Solution

The assembly features a cannula with a hub having contiguous bores and a stop mechanism that allows the electrode to be slip-fitted and locked in place with minimal force, ensuring consistent distal extension and easy interchange with a syringe, facilitating zero-force insertion and withdrawal of the electrode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the electrode is removed and reinserted into the cannula during a nerve ablation procedure, then the syringe can be used to deliver anesthetic, but the electrode cannot be precisely repositioned to extend the same distance out of the cannula

Engineering Contradiction:

Improveinterchangeability of electrode and syringeVSAvoidelectrode distal extension position

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The electrode and syringe heads feature self-aligning complementary geometries (polygonal outer surfaces matching corresponding inner surfaces) that automatically ensure correct positioning when inserted into the cannula hub, eliminating the need for manual alignment and ensuring consistent distal extension without requiring precise measurement or adjustment

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The electrode and syringe heads incorporate asymmetric polygonal outer surfaces with specific numbers of sides (e.g., hexagonal, octagonal) that mate with corresponding asymmetric inner surfaces in the cannula hub, creating unique orientation references that ensure each component can only be inserted in the correct rotational position, thereby maintaining precise and repeatable electrode distal extension

Inventive Principle:

Principle #4Asymmetry

2Measurement precision

If the electrode is manually repositioned after removal, then the distal end can be placed back in the cannula, but significant time is required to achieve precise positioning

Engineering Contradiction:

Improveelectrode distal extension positionVSAvoidprocedure time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The cannula hub, electrode, and syringe are pre-configured with complementary geometric features (polygonal surfaces, tapered sections, and matching bore dimensions) that automatically guide and lock the electrode into the correct position upon insertion, eliminating the need for time-consuming manual repositioning and ensuring consistent distal extension immediately upon insertion

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The self-aligning geometric features on the electrode and syringe heads automatically perform the positioning function when inserted into the cannula hub, requiring no manual intervention for alignment or adjustment, thereby eliminating the time loss associated with manual repositioning while ensuring precise and repeatable electrode distal extension

Inventive Principle:

Principle #25Self-service

3Ease of operation

If conventional cannula hubs are used with large diameter bores, then the electrode can be inserted, but significant force is required and precise positioning becomes difficult

Engineering Contradiction:

Improveelectrode insertion easeVSAvoidelectrode distal extension position

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The cannula hub bore and electrode/syringe head interfaces feature localized geometric features (polygonal outer surfaces matching inner surfaces, tapered sections with specific angle ranges) that provide precise alignment and positioning guidance at the insertion point, while the overall bore diameter remains optimized for easy insertion with minimal force, combining ease of operation with precise positioning

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The asymmetric polygonal surfaces create unique mechanical interlocking features that guide the electrode into the correct rotational orientation during insertion, ensuring precise distal extension position is achieved automatically without requiring excessive force or manual adjustment, as the asymmetric geometry self-aligns the components

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS11678929B2Assembly for sequentially percutaneously applying an electrode and an anesthetic to tissue

Publication Date: 2023.06.20 STRYKER CORP

AI summary

An assembly for performing an electrosurgical procedure. A cannula includes a cannula hub defining a middle bore having a smaller diameter than a proximal bore. An electrode includes an electrode head having an outer diameter smaller than the proximal bore and greater than the middle bore. A syringe includes a syringe head having a length sufficient to extend past the proximal bore, and an outer diameter sized to engage the middle bore to form an annular seal at an interface between the syringe and the cannula. A step may define a transition surface between the proximal bore and the middle bore, and at least one notch may be within the step to maintain fluid communication between the middle bore and the proximal bore when the electrode head is engaging the step. The cannula head may include first and second locking features configured to engage the syringe and electrode, respectively.