Flexible Knife Bar for Surgical Loading Unit Articulation

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Solution Overview

Problem

Existing surgical instruments face challenges in articulating end effectors without damaging knife blades due to bending moments and shear forces during endoscopic procedures, limiting access and efficiency in surgical sites.

Innovation Solution

A surgical loading unit with a flexible knife bar and elongate guide member, where the knife bar bends and shifts in a direction opposite to articulation, maintaining a larger radius of curvature to reduce stress and enhance articulation angles, combined with an articulation assembly that includes a drive nut, drive screw, and articulation link for precise movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the end effector articulates relative to the elongate body during endoscopic procedures, then access to surgical sites is improved, but the knife blade experiences bending moments and shear forces that degrade it over time

Engineering Contradiction:

Improveaccess to surgical sitesVSAvoidknife blade durability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The knife assembly is segmented into multiple components: a rigid proximal portion, a flexible intermediate portion, and a distal portion with the knife blade. This segmentation allows the flexible intermediate portion to absorb bending moments and shear forces during articulation, protecting the knife blade from degradation while enabling the end effector to articulate for improved surgical site access.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The knife bar transitions from a rigid structure to a flexible structure with specific mechanical properties. The flexible intermediate portion is designed with controlled flexibility parameters that allow it to deflect under bending moments and shear forces generated during articulation, thereby protecting the knife blade while maintaining cutting functionality.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the knife bar is made flexible to accommodate articulation, then the knife blade is protected from damage, but the guide member must maintain linearity to ensure precise cutting

Engineering Contradiction:

Improveknife blade protectionVSAvoidguide member linearity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The guide member is segmented into a rigid proximal portion that maintains linearity and a flexible distal portion that accommodates articulation. This segmentation allows the guide member to provide precise guidance for the knife blade while simultaneously protecting it from damage during end effector articulation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the guide member have different mechanical properties: the proximal portion is rigid to maintain linearity and precision, while the distal portion is flexible to protect the knife blade. This local differentiation of quality allows the guide member to fulfill both functions simultaneously.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11723660B2Surgical loading unit including an articulating end effector

Publication Date: 2023.08.15 COVIDIEN LP

AI summary

A surgical loading unit includes an elongate body, an end effector pivotably coupled to the elongate body, and a flexible knife bar extending through a distal portion of the elongate body and a proximal portion of the end effector. Articulation of the end effector relative to the elongate body in a first direction moves a first segment of the knife bar in the first direction and moves a second segment of the knife bar in a second direction, opposite the first direction.