Frangible Retaining Member for Anvil Tilting in Staplers
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Solution Overview
Problem
Existing tiltable anvil assemblies in circular anastomosis staplers face issues where the backup plate may stick to the knife blade upon retraction, preventing the anvil head from tilting due to residual proximal forces, which can cause the backup plate to return to its original position and prevent tilting of the anvil assembly.
Innovation Solution
An anvil assembly design featuring a frangible retaining member that maintains the backup plate in a proximal position until a predetermined force is applied, allowing it to move distally during firing, and includes a cam latch member to prevent the backup plate from returning to its original position, ensuring the anvil head can tilt properly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a retainer member with deformable tabs is used to hold the backup plate in the proximal position, then the backup plate is securely retained before firing, but a residual proximal force is produced during tab deformation that may cause the backup plate to return to its original position and prevent the anvil head from tilting
Solution Approach 1:
The retainer member is divided into a body portion and a frangible portion that can separate from each other. The frangible portion engages the backup plate to provide retention, while the body portion remains stationary. This segmentation allows the frangible portion to be discarded after serving its purpose, eliminating residual forces that would prevent tilting.
Solution Approach 2:
The frangible portion of the retainer member is designed to be discarded after use. It separates from the body portion following backup plate movement, allowing the backup plate to remain in the distal position without residual restraining forces. The discarded frangible portion has served its function of secure retention during the firing process.
2Ease of operation
If the backup plate is allowed to move distally during firing, then the anvil head can tilt properly, but the backup plate may stick to the knife blade upon retraction and return to its original position, preventing tilting
Solution Approach 1:
The frangible retainer member acts as an intermediary between the backup plate and the housing. It provides controlled engagement and retention during firing, then separates to allow the backup plate to remain in its distal position without sticking to the knife blade, ensuring reliable anvil head tilting.
3Reliability
If deformable tabs are used to prevent distal movement of the backup plate, then retention is achieved until predetermined force is applied, but the residual proximal force acts on the backup plate after firing and prevents tilting
Solution Approach 1:
The retainer member is segmented into a body portion and a frangible portion. This simple segmentation provides the needed retention function during firing while eliminating complex deformable tab mechanisms that produce residual forces. The frangible portion can be easily manufactured and discarded after use.
Data Source
AI summary
An anvil assembly includes a retaining member having a body portion and a frangible portion connected to the body portion, where the frangible portion is positioned to engage a backup member and separates from the body portion during movement of the backup member from a first, proximal position to a second, distal position. The retaining member keeps the backup plate in the proximal position prior to firing of the stapling assembly, and upon separation of the frangible portion allows the backup plate to move to the distal position during firing of the stapling assembly. Proximal force on the backup plate after firing of the stapling assembly is avoided, thereby helping to ensure titling of the anvil assembly.