Cannula Retention Anchor With Switchable Friction Locking
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Solution Overview
Problem
Surgical access devices face challenges in maintaining secure fixation within tissue during minimally invasive procedures, particularly in preventing retropulsion and over-insertion of cannulas during instrument manipulation and withdrawal, which can compromise the integrity of the pneumoperitoneum and surgical access.
Innovation Solution
A retention anchor system comprising an annular body and a washer, where the washer transitions between a slidable and a locking configuration, providing a friction fit to secure the cannula in place, is used in conjunction with an expandable anchor to prevent longitudinal movement of the cannula relative to the tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a retention anchor is designed to provide strong fixation force on the surgical access device, then the reliability of securing the device in tissue is improved, but the force required to move the retention anchor relative to the surgical access device increases
Solution Approach 1:
The retention anchor employs a dynamic locking mechanism where the washer can transition between a locked position (providing strong fixation) and an unlocked position (allowing easy movement). The resilient arm enables the system to shift from a high-friction state during insertion to a low-friction state for adjustment, resolving the contradiction between strong fixation and ease of movement.
Solution Approach 2:
The friction coefficient between the washer and cannula shaft is dynamically changed through the resilient arm mechanism. When the resilient arm is depressed, the washer moves to engage the cannula shaft with high friction for secure fixation. When released, the washer can slide easily along the shaft, allowing repositioning without excessive force.
2Stability of the object's composition
If the retention anchor is designed to prevent retropulsion and over-insertion of the cannula, then the stability of the surgical access device in tissue is improved, but the ease of operation for adjusting the retention anchor position deteriorates
Solution Approach 1:
The retention anchor system allows dynamic adjustment during surgery. The resilient arm enables the surgeon to temporarily overcome the locking force to reposition the anchor, then re-engage the lock to restore stability. This dynamic capability resolves the contradiction between maintaining stable position and allowing easy adjustment when needed.
Solution Approach 2:
The resilient arm provides automatic locking and unlocking functionality. When the surgeon applies force to reposition the anchor, the resilient arm automatically disengages the washer from the locked position, allowing movement. Once positioning is complete, the resilient arm naturally returns to lock the washer, providing self-service stability without requiring additional locking actions.
3Reliability
If the washer is designed to engage the elongated shaft to fix the retention anchor in place, then the reliability of securing the surgical access device is improved, but the ease of manufacture and assembly deteriorates
Solution Approach 1:
The retention anchor is divided into distinct functional segments: the annular body, the resilient arm, and the washer. This segmentation allows each component to be manufactured independently using optimized processes, then assembled through a simple snap-fit or press-fit mechanism, reducing overall manufacturing complexity while maintaining reliable engagement.
Solution Approach 2:
The resilient arm is designed as a thin, flexible component that can be easily formed from sheet material or molded as a thin-walled structure. This flexible element provides the necessary elastic properties for locking and unlocking while being simple to manufacture and assemble, resolving the contradiction between reliable securing and ease of manufacture.
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 retention anchor system effectively secures the surgical access device, minimizing the force required for movement and enhancing fixation, thereby maintaining the integrity of the pneumoperitoneum and preventing cannula displacement during surgical procedures.
Implementation Method 1
The inner side surface of the annular body frictionally engages the elongated shaft of the cannula
Data Source
AI summary
A surgical access assembly includes a cannula and a retention anchor including an annular body and a washer secured to the annular body. The annular body includes an inner side surface defining an opening therethrough, and the washer includes an inner terminal edge defining an opening therethrough that is aligned with the opening of the annular body. The elongated shaft of the cannula extends through the openings. The washer is transitionable between a first configuration in which the inner terminal edge of the washer is coincident with or disposed radially outwardly of the inner side surface of the annular body so that the retention anchor is slidable along the elongated shaft, and a second configuration in which the inner terminal edge of the washer extends radially inwardly of the inner side surface of the annular body and engages the elongated shaft to fix the retention anchor to the elongated shaft.