Surgical Stapling Instrument Firing Member Return Mechanism

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Solution Overview

Problem

Surgical staplers face challenges in preventing the end effector from being articulated after closure, which can apply shear forces to soft tissue, and require significant force to extend the cutting member and manage the return spring, leading to premature return and multiple trigger strokes.

Innovation Solution

A surgical instrument with a firing drive and reversing drive mechanism, including a pawl and gear train, that advances and retracts the firing member, and an anti-backup mechanism with an indexing mechanism to prevent unintended movement of the firing member, allowing controlled advancement and retraction with fewer strokes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a return spring is used to retract the cutting member, then the cutting member can be returned to its starting position, but the force required to extend the spring is significant and can cause premature return

Engineering Contradiction:

Improvecutting member retraction controlVSAvoidforce required to extend return spring

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

A return carriage acts as an intermediary mechanism between the trigger and the cutting member. The carriage translates the trigger's distal movement into proximal movement of the cutting member through a rack and pinion gear system, eliminating the need for a high-force return spring while maintaining reliable retraction control

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The traditional spring-based mechanical return system is replaced with a gear-driven mechanical advantage system. The return carriage engages a pinion gear that rotates a rack attached to the cutting member, providing controlled retraction through mechanical advantage rather than elastic force

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If multiple trigger strokes are required to advance the cutting member, then complete advancement can be achieved, but the operation becomes more complex and time-consuming

Engineering Contradiction:

Improvecutting member advancement controlVSAvoidnumber of trigger strokes required

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The firing trigger provides continuous useful action by maintaining engagement with the return carriage throughout its distal movement. This single continuous action advances the cutting member completely through the channel without requiring multiple discrete strokes, improving operational efficiency while maintaining precise control

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system dynamically transitions between different operational modes within a single trigger stroke. The return carriage selectively engages and disengages from the trigger at appropriate points during its travel, enabling both advancement and retraction phases to occur within one continuous triggering action

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If the end effector can be articulated after closure, then repositioning is possible, but shear force is applied to the soft tissue

Engineering Contradiction:

Improveend effector repositioning capabilityVSAvoidshear force on soft tissue

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system takes preliminary anti-action by preventing articulation of the end effector after the jaw members are closed. A locking mechanism engages to prohibit further articulation, thereby preventing shear force from being applied to the captured soft tissue while maintaining the ability to reposition before closure

Inventive Principle:

Principle #9Preliminary anti-action

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 solution enables precise control over the firing member's movement, reducing tissue damage and the force required for operation, while ensuring complete advancement and retraction with fewer trigger strokes, improving the efficiency and reliability of the surgical stapler.

Implementation Method 1

a return spring which retracts the cutting member relative to the staple cartridge after a release button or toggle switch on the surgical stapler has been actuated

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a gear mechanism engaged to the rack, a handle containing the rack, firing mechanism and gear mechanism, and a retraction member mounted for rotation external to the handle and coupled for rotation to the gear mechanism

Methodology Applied

Scientific EffectMechanical Advantage: Mechanical Advantage

Data Source

PatentEP2455006B1Surgical stapling instrument with a firing member return mechanism

Publication Date: 2023.06.28 ETHICON ENDO SURGERY INC

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AI summary

A surgical instrument including a firing drive configured to selectively advance a firing member and/or cutting member relative to an end effector and, in addition, a reversing drive configured to selectively retract the firing member and/or cutting member relative to the end effector. In various embodiments, the surgical instrument can further include a switch including relatively movable first and second portions, wherein the first portion can be configured to operably disengage the firing drive from the firing member and, in addition, operably engage the reversing drive with the firing member. In at least one embodiment, the second portion can include a handle extending therefrom which can be motivated by the surgeon in order to engage the second portion with the first portion and move the first portion into position.