Stapling Device Knife Carrier Reliability

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Solution Overview

Problem

Conventional circular stapling devices face issues with the engagement and disengagement of the knife carrier and knife carrier pusher, leading to potential damage or premature separation, due to the back angle selection being too small or large, which affects the full retraction of the knife.

Innovation Solution

The surgical stapling device incorporates a reload member with a first engagement structure on resilient legs and a second engagement structure, where the reload member includes a tapered portion to control the movement of the knife carrier from an engaged to a disengaged position, preventing premature separation and ensuring full retraction of the knife by accommodating inward movement of the resilient legs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a back angle is formed on the knife carrier pusher to facilitate separation, then the ease of operation is improved, but if the back angle is too small, the reliability deteriorates due to potential damage to the knife carrier, and if the back angle is too large, the reliability deteriorates due to premature disengagement

Engineering Contradiction:

Improveseparation of knife carrier pusher from knife carrierVSAvoidengagement and disengagement timing

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent changes the geometric parameter of the back angle on the knife carrier pusher to optimize both ease of separation and reliability. By carefully selecting the back angle within a specific range, the design achieves sufficient ease of operation while preventing both knife carrier damage and premature disengagement, thus resolving the reliability concern associated with angle selection

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The engagement structure between the knife carrier pusher and knife carrier is designed to be dynamic, allowing automatic engagement during assembly and controlled disengagement during operation. The back angle creates a mechanical interaction that naturally guides the components into proper engagement while enabling reliable separation when needed, adapting the connection state based on operational requirements

Inventive Principle:

Principle #15Dynamics

2Ease of manufacture

If the knife carrier and knife carrier pusher are separable to facilitate reload assembly separation, then the ease of manufacture is improved, but the reliability may deteriorate due to potential premature separation or damage

Engineering Contradiction:

Improveseparation of reload assembly from elongate bodyVSAvoidknife carrier pusher and knife carrier connection

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The design segments the reload assembly by making the knife carrier separable from the knife carrier pusher, allowing the reload assembly to be easily separated from the elongate body for manufacturing and reloading purposes. This segmentation is achieved through the back angle engagement structure that enables clean separation without compromising the reliability of the connection during operational phases

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The back angle engagement structure acts as an intermediary mechanism between the knife carrier pusher and knife carrier. It provides a controlled interface that allows reliable connection during operation while enabling safe separation during manufacturing and reloading, mediating between the conflicting requirements of separability and reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This solution minimizes the likelihood of premature separation of the knife carrier from the knife carrier pusher while reducing the force required for separation, ensuring reliable engagement and disengagement at appropriate times, thus maintaining the integrity of the device.

Implementation Method 1

a first engagement structure on resilient legs

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP3318200B1Stapling device with releasable knife carrier

Publication Date: 2020.01.01 COVIDIEN LP

Figure 1
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AI summary

A circular surgical stapling device includes a reload assembly that is supported on a distal end of an elongate shaft of the stapling device. The reload assembly includes a housing, a pusher assembly movably supported within the housing, a knife carrier movably supported within the pusher assembly, and an annular knife supported on the knife carrier. The elongate body includes a pusher drive member and a knife carrier pusher. The knife carrier 30 includes first engagement structure 60 that is configured to releasably engage second engagement structure 80 formed on the knife carrier pusher 70 to releasably couple the knife carrier pusher 70 to the knife carrier 30. A reload insert or member 39 is supported on or integrally formed with the housing 26 of the reload assembly 16. The reload member 39 includes a first portion 94a configured to prevent separation of the first and second engagement structures 60,80 and a second portion 94b configured to accommodate separation of the first and second engagement structures 60,80. The reload member 39 minimizes the likelihood of premature disengagement of the knife carrier 30 from the knife carrier pusher 70 while minimizing the force required to effect separation after the knife 32 has been fully retracted into the housing 26.