Flexible Endoscopic Torqueable Scissors
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Solution Overview
Problem
Current endoscopic surgical scissors with rigid constructions are inadequate for minimally invasive procedures through flexible endoscopes, as they fail to provide comparable performance to laparoscopic scissors, especially when lengths exceed 300 cm, resulting in poor performance characteristics.
Innovation Solution
A flexible endoscopic scissor instrument featuring a coaxial arrangement of an elongate hollow multi-wire stranded cable and a helically wound coil, secured by welds, allows for precise orientation and actuation of scissor blades through a flexible shaft, enabling effective use within a working channel of a flexible endoscope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rigid construction is used for endoscopic surgical scissors, then precise orientation control and ease of cutting are achieved, but the instrument cannot be used through flexible endoscopes and cannot adapt to minimally invasive procedures
Solution Approach 1:
The patent replaces the rigid tubular shaft with a flexible shaft constructed from multiple wire strands (including hollow strands) that can bend and conform while maintaining structural integrity. This flexible construction allows the instrument to pass through the flexible endoscope's working channel while still providing adequate support for blade actuation and orientation control at the distal end.
Solution Approach 2:
The shaft employs a composite construction combining multiple wire strands of different materials and properties (solid wires for strength, hollow wires for flexibility and potential fluid passage) twisted together. This composite structure achieves a balance between flexibility for navigation and rigidity for torque transmission and precise control of the scissor blades.
2Length of moving object
If the shaft length is increased to exceed 300 cm for deeper surgical access, then minimally invasive procedures through natural orifices become possible, but performance characteristics deteriorate with rigid constructions
Solution Approach 1:
The flexible wire strand construction maintains reliability over extended lengths (100-350 cm) by allowing the shaft to naturally conform to body cavities and passages without creating excessive stress concentrations or losing structural integrity. The flexibility enables the long shaft to navigate complex anatomical pathways while maintaining adequate torque transmission to the distal end.
Solution Approach 2:
The shaft is segmented into multiple independent wire strands that can move relative to each other, allowing the long instrument to bend and flex along its entire length. This segmentation prevents the development of excessive stresses that would occur in a rigid construction of equivalent length, thereby maintaining performance characteristics throughout the extended shaft length.
3Adaptability or versatility
If a flexible construction is used for the shaft, then adaptability to minimally invasive procedures is improved, but torque transmission to the distal end and precise orientation control are reduced
Solution Approach 1:
The composite wire strand construction includes solid wires providing tensile strength and torque resistance, combined with hollow wires enhancing flexibility. The specific arrangement and material selection of these composite strands optimize the balance between flexibility for navigation and stiffness for torque transmission, ensuring adequate force delivery to actuate the scissor blades at the distal end.
Solution Approach 2:
The shaft exhibits varying local properties along its length, with the wire strand configuration and material composition optimized for different functional zones. The proximal portion may have higher stiffness for operator control, while distal portions maintain flexibility for navigation, with intermediate sections providing the transition and torque transmission necessary for reliable blade actuation.
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 flexible design enhances the ability to perform minimally invasive procedures by providing precise control and adaptability, matching the performance of laparoscopic scissors while maintaining flexibility suitable for various endoscopic and open surgical procedures.
Implementation Method 1
an elongate flexible torque transmitting shaft member... Rotation of the proximal end of the shaft member causes the distal end of the shaft member to rotate accordingly
Implementation Method 2
The hollow cable is secured to the coil in at least two locations along the length of the shaft, preferably at the proximal and distal ends and preferably by laser welding
Data Source
AI summary
An elongate flexible endoscopic surgical scissor instrument includes an actuating means at the proximal end and a blade assembly that includes pair of pivotable scissor blades at the distal end. The actuating means is adapted to place the scissor blades in an opened or closed configuration. The scissors include a torque-transmitting shaft assembly that couples the proximal end of instrument to the blade assembly positioned at the distal end. Rotation of the torque transmitting shaft assembly at the proximal end causes the distally-located blade assembly to similarly rotate in both the open and closed configurations, which can provide precise targeting.