Flexible Surgical Stapler Adapter With Cycloid Torque Multiplication

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Solution Overview

Problem

Rigid elongate shafts of surgical staplers hinder the introduction of stapling assemblies through tortuous paths within a body cavity, necessitating a flexible solution for effective surgical procedures.

Innovation Solution

A surgical adapter with a flexible elongate body, incorporating a cycloid gear assembly to increase input torque for stapling and cutting, and a push/pull cable mechanism for gross movement of the trocar member, allowing for flexible navigation through curved anatomies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a rigid elongate shaft is used in the surgical stapler, then the structural stability and torque transmission are improved, but the ability to navigate through tortuous paths within the body cavity deteriorates

Engineering Contradiction:
Improvestructural stabilityVSAvoidability to navigate tortuous paths
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The elongate shaft is divided into multiple rigid segments connected by flexible joints. Each segment maintains structural integrity while the joints between segments provide flexibility to navigate tortuous paths, resolving the contradiction between rigidity for stability and flexibility for navigation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The shaft transitions from a static rigid structure to a dynamic articulated structure where segments can relative move. This allows the shaft to adapt its configuration to navigate complex anatomical paths while maintaining rigidity within each segment for stable torque transmission.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If a flexible elongate shaft is used to navigate tortuous paths, then the adaptability to anatomical contours is improved, but the torque transmission capability and structural stability deteriorate

Engineering Contradiction:
Improveflexibility to navigate pathsVSAvoidtorque transmission stability
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

By segmenting the shaft into rigid sections connected by flexible joints, each segment maintains torque transmission capability while the inter-segment joints provide the necessary flexibility to navigate tortuous paths, preventing torque loss.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The shaft employs composite construction combining rigid materials for torque-carrying segments with flexible materials for connecting joints, achieving both high torque transmission stability and adaptability to navigate complex anatomical paths.

Inventive Principle:
Principle #40Composite materials

3Speed

If high-speed rotation is used to actuate the stapling mechanism, then the operation speed is improved, but the torque required for staple ejection and tissue cutting deteriorates

Engineering Contradiction:
Improverotation speedVSAvoidtorque for staple ejection
Core Design Contradiction:
SpeedVSForce

Solution Approach 1:

A cycloid gear assembly serves as an intermediary mechanism between the high-speed rotation source and the staple ejection mechanism. The gear assembly converts high-speed rotation into high-torque rotational motion, enabling both rapid operation and sufficient force for staple ejection and tissue cutting.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The mechanism discards rotational speed in favor of torque through the cycloid gear reduction, recovering the energy as mechanical work for staple ejection. This speed-torque conversion allows the system to operate at high speeds while delivering the necessary force.

Inventive Principle:
Principle #34Discarding and recovering

4Force

If a complex gearing arrangement is added to increase torque, then the force for staple ejection is improved, but the device complexity and manufacturing difficulty deteriorate

Engineering Contradiction:
Improvetorque for staplingVSAvoidgearing arrangement complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The cycloid gear assembly acts as a compact intermediary that efficiently multiplies torque in a space-efficient manner. Compared to alternative gearing arrangements, it achieves high torque multiplication with fewer components and simpler manufacturing requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The cycloid gear mechanism changes the mechanical parameters of the drive system by converting high-speed rotation to high-torque rotation through its geometric configuration, achieving torque multiplication without complex multi-stage gearing arrangements.

Inventive Principle:
Principle #35Parameter changes

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

Facilitates the introduction and positioning of stapling assemblies within body cavities through natural orifices or incisions, enabling precise stapling and cutting while accommodating anatomical contours.

Implementation Method 1

The firing assembly includes a cycloid gear assembly for increasing an input torque from the first drive assembly to actuate the firing assembly

Methodology Applied
Scientific EffectCycloid gear mechanism: Gear

Implementation Method 2

The second drive assembly includes a drive screw and a push/ pull cable movably secured to the drive screw by a threaded nut. The trocar member is disposed on a distal portion of the push/pull cable and rotation of the drive screw causes longitudinal movement of the push/pull cable.

Methodology Applied
Scientific EffectScrew mechanism: Screw

Data Source

PatentEP3415102B1Adapter assembly for surgical stapling instrument
Publication Date: 2021.01.27 COVIDIEN LP
  • EP3415102B1 patent drawingFigure 1
  • EP3415102B1 patent drawingFigure 2
  • EP3415102B1 patent drawingFigure 3

AI summary

A flexible surgical stapler includes an adapter having a coupling assembly configured for securing the adapter assembly to a handle assembly, an elongate body extending from the coupling assembly, a first drive assembly extending through the elongate body, and a loading unit secured to a distal portion of the elongate body. The loading unit includes a firing assembly operably connected to the first drive assembly. The firing assembly includes a cycloid gear assembly for increasing an input torque from the first drive assembly to actuate the firing assembly. The flexible surgical stapler may include an introducer assembly to facilitate introduction of a stapling portion of the surgical stapler into a body cavity of a patient.