Circular Stapler Knife Retraction Mechanism
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Solution Overview
Problem
Current circular surgical staplers lack an effective mechanism for releasing tissue from the stapling head assembly after anastomosis, leading to potential adhesion and hindering the proper release of the formed anastomosis.
Innovation Solution
The design incorporates a knife retracting assembly with a knife coupling ring and cam features that allow the knife to retract after the initial firing, enabling the staple drivers to actuate a second time to push tissue off the deck surface, facilitating tissue release and preventing adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the circular surgical stapler uses a motorized actuation mechanism to drive the anvil and staple drivers, then the anastomosis formation process is automated and efficient, but there is no mechanism to release tissue from the stapling head assembly after anastomosis, causing tissue adhesion
Solution Approach 1:
The knife is designed to be movable rather than fixed, transitioning between extended and retracted positions. The motorized actuation mechanism dynamically adjusts the knife position: extending it to cut tissue during anastomosis formation, then retracting it to allow staple drivers to push tissue off the deck surface for release. This dynamic adjustment resolves the contradiction between automated anastomosis formation and tissue release capability.
2Manufacturing precision
If the knife remains extended to cut tissue during stapling, then precise cutting is achieved, but tissue adheres to the deck surface and cannot be released
Solution Approach 1:
The knife position is dynamically controlled based on the surgical phase. During the cutting phase, the knife extends to provide precise cutting action. After cutting is complete, the knife retracts to a retracted position where it no longer interferes with tissue release, eliminating the adhesion problem. This temporal separation of functions resolves the contradiction between cutting precision and tissue release.
Solution Approach 2:
The cutting and tissue release functions are segmented into distinct phases with the knife serving different roles in each phase. The knife is active only during the cutting phase and inactive during the tissue release phase, allowing each function to be optimized independently without interfering with the other.
3Strength
If the stapler forms an anastomosis by clamping tissue between the anvil and deck surface, then secure joining is achieved, but the tissue remains adhered and requires manual release
Solution Approach 1:
The system uses dynamic positioning of the knife and staple drivers to transition from the clamping phase (where strong joining is achieved) to the release phase. After anastomosis formation, the knife retracts and staple drivers are actuated to push tissue off the deck surface, providing an automated release mechanism that maintains both joining strength and release ease.
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 ensures proper release of the anastomosis by preventing tissue adhesion to the stapling head assembly, allowing for successful separation and secure joining of anatomical structures.
Implementation Method 1
The knife retracting assembly includes a knife coupling ring and cam features that allow the knife to retract after the initial firing
Data Source
AI summary
A surgical stapling instrument includes an anvil defining a plurality of staple forming pockets, and a stapling head assembly, and a retracting assembly. The stapling head assembly includes a body, a coupling member capable of actuating the anvil, a deck surface, a staple driver assembly, and a knife member. The staple driver assembly actuates through a first firing stroke and a second firing stroke. In the first firing stroke, the staple driver assembly drives a plurality of staples against the staple forming pockets. In the second firing stroke, the staple driver actuates distally past the deck surface. The knife member includes a cutting edge that can sever tissue during the first firing stroke while remaining in a retracted position that is proximal relative to the staple deck surface during the second firing stroke. The retracting assembly can drive the knife member into the retracted position during the first firing stroke.