Endoscopic Cam-Slot Mechanism for Navigating Rigid Bends
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Solution Overview
Problem
Existing endoscopic surgical instruments face challenges in navigating non-flexible bends within the working channel of an endoscope due to their rigid design, limiting the length and flexibility of end effectors that can be used during minimally invasive procedures.
Innovation Solution
The development of an endoscopic instrument with scissors blades featuring a cam-slot and cam-pin operation, allowing for rotation and a friction-enhancing tissue stop, which enables the end effector to traverse non-flexible bends and provides precise rotational manipulation, while a flexible control member with varying stiffness ensures smooth operation even in retroflexed endoscopes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If endoscopic instruments use rigid design for structural stability, then cutting precision is improved, but the ability to navigate non-flexible bends in working channels deteriorates
Solution Approach 1:
The endoscopic instrument is divided into multiple segments including a flexible tubular member, a clevis assembly, and an end effector. The flexible tubular member can bend to navigate curves while the end effector remains rigid for precise cutting. This segmentation allows different parts to have different flexibility characteristics, resolving the contradiction between overall flexibility and local rigidity.
Solution Approach 2:
The instrument incorporates a flexible tubular member with a flexible wall that can bend and conform to the curved path of the endoscope working channel. This flexible shell allows the instrument to navigate non-flexible bends while maintaining structural integrity, enabling the rigid end effector to reach positions that would otherwise be inaccessible.
2Length of moving object
If end effectors are made longer to reach deeper tissue, then surgical capability is improved, but the ability to traverse non-flexible bends deteriorates
Solution Approach 1:
The long end effector is segmented into a flexible distal portion and a rigid proximal portion. The flexible distal portion navigates the curved path through the endoscope, while the rigid proximal portion provides cutting precision. This segmentation enables the end effector to be long enough to reach deep tissue while still being able to traverse bends.
Solution Approach 2:
The end effector incorporates a flexible section that can dynamically bend and conform to the working channel path, while the cutting portion remains rigid. This dynamic flexibility allows the long end effector to navigate bends during insertion and positioning, then maintain rigidity when performing cutting operations.
3Measurement precision
If cam-slot is designed with tight fit for precise control, then rotational manipulation precision is improved, but the ability to rotate through non-flexible bends deteriorates
Solution Approach 1:
The cam-slot is designed with different geometries in different sections. The distal portion has a tighter fit for precise rotational control, while the proximal portion has a wider fit that allows greater rotational freedom for navigating bends. This local variation in slot geometry enables both precise manipulation and adaptability to curved paths.
Solution Approach 2:
The cam-slot design allows the end effector to dynamically adjust its rotational characteristics. During navigation through bends, the wider proximal section allows greater rotational movement. During cutting operations, the tighter distal section provides precise rotational control. This dynamic adaptability resolves the contradiction between precision and bend traversal capability.
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 design allows for the use of longer end effectors, enhances tissue handling by preventing slippage, and facilitates precise rotational control, improving the versatility and effectiveness of endoscopic procedures by enabling the passage of instruments through smaller entry ports and maintaining functionality within curved endoscope paths.
Implementation Method 1
The proximal end of the cam slot includes a bilaterally widened area... when the pin is fully retracted into the bilaterally widened area the end effector elements are now free to rotate together
Implementation Method 2
laterally offset from the cutting edges at least one of the blades of an endoscopic scissors, and preferably both of the blades, includes a friction enhancing tissue stop that functions to hold and/or put traction on tissue
Data Source
AI summary
An endoscopic instrument includes a tubular member having a proximal end and a distal end, a clevis at the distal end of the tubular member, and an end effector assembly mounted on the clevis. A control member extends through the tubular member and includes a cam-pin coupled to the distal end thereof. The end effectors are controlled with a cam-pin and cam-slot arrangement, with the end effectors including the cam-slot and such cam-slot having a proximal end slot bilaterally widened to permit the cam-pin additional movement therein. When the cam-pin is retracted to move the end effectors into a closed positions and then further retracted into the bilaterally widened area, the end effectors can rotate together in the same direction to facilitate movement through a rigid bend in an endoscope.