Stylet Cannula Locking Assembly for PCNL Access

Solution Overview

Problem

In percutaneous nephrolithotomy (PCNL) procedures, the precise placement of needles into the kidney is challenging due to the risk of the stylet popping out of the cannula, requiring significant experience and often radiological assistance, which increases operating time and patient radiation exposure.

Innovation Solution

A medical device assembly with a stylet and cannula featuring a locking mechanism, such as protrusions and channels or threaded projections, to securely couple the stylet to the cannula, preventing accidental disengagement during insertion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a stylet and cannula are used for PCNL access without a locking mechanism, then the device structure is simple, but the stylet may pop out of the cannula during insertion, reducing reliability

Engineering Contradiction:

Improvestylet retention in cannulaVSAvoidlocking mechanism structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The stylet hub is inserted into and nested within the cannula hub, with the stylet positioned inside the cannula body. The locking mechanism uses internal protrusions and channels that engage when the hubs are coupled, creating a secure nested configuration that prevents stylet disengagement while maintaining a compact overall structure.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The locking mechanism is divided into separate components: protrusions on one hub and corresponding channels on the other hub. These segmented elements can be manufactured independently and then assembled, allowing for simplified production while providing reliable mechanical interlocking to prevent stylet pop-out during insertion.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If radiological assistance is used to ensure accurate needle placement, then placement precision is improved, but operating time and patient radiation exposure increase

Engineering Contradiction:

Improveneedle placement accuracyVSAvoidoperating time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The locking mechanism is pre-configured with protrusions and channels that automatically engage when the stylet hub is inserted into the cannula hub. This preliminary mechanical arrangement ensures accurate stylet positioning and prevents pop-out during insertion, eliminating the need for continuous radiological monitoring and reducing operating time while maintaining placement precision.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If radiological assistance is used to ensure accurate needle placement, then placement precision is improved, but patient radiation exposure increases

Engineering Contradiction:

Improveneedle placement accuracyVSAvoidpatient radiation exposure

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The locking mechanism is pre-configured with protrusions and channels that automatically engage when the stylet hub is inserted into the cannula hub. This preliminary mechanical arrangement ensures accurate stylet positioning and prevents pop-out during insertion, eliminating the need for continuous radiological monitoring and reducing operating time while maintaining placement precision.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20230346422A1Locking assembly for medical device

Publication Date: 2023.11.02 BOSTON SCI LTD

AI summary

A medical device assembly may include a stylet having a distal stylet body and a proximal stylet hub, a cannula having a distal cannula body and a proximal cannula hub, and a lock for securing the stylet to the cannula, wherein the lock includes at least one abutment on at least one of the stylet hub and the cannula hub for restricting relative movement between the stylet hub and the cannula hub.