Flexible Inner Member With Offset Cuts For Torque Transmission
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Solution Overview
Problem
Existing angled rotary tissue cutting instruments face challenges in minimizing external diameter, maximizing internal diameter, and reducing structural complexity and costs while maintaining sufficient strength and rigidity in flexible inner members to effectively transmit torque and aspirate tissue/fluid, especially when operating at high speeds and cutting hard tissues.
Innovation Solution
A flexible inner member with partial circumferential cuts formed in a tubular body, arranged in duplicate patterns of rotational offset, which allows for torque transmission and flexibility without additional structural components, minimizing annular wall thickness and maintaining internal diameter integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the flexible region is formed with multiple structural components or parts, then the ability to transmit torque and maintain strength is improved, but the structural complexity and manufacturing costs increase
Solution Approach 1:
The flexible region is segmented into multiple discrete flex elements formed by longitudinal cuts through the tubular body. These flex elements are arranged in a circumferential pattern and connected by bridging portions, creating a segmented structure that maintains torque transmission while enabling flexibility. The segmentation allows each element to deform independently, providing the necessary compliance without requiring multiple separate components.
Solution Approach 2:
The patent merges the flexible region design into a single integrated tubular body with cuts formed directly in it, eliminating the need for separate flexible components that would need to be assembled. The flex elements, bridging portions, and tubular body are combined into one piece, reducing structural complexity and manufacturing steps while maintaining the required flexibility and strength properties.
2Strength
If the annular wall thickness is increased to maintain strength during torque transmission, then the torque transmission capability is improved, but the external diameter increases and the internal diameter decreases
Solution Approach 1:
The tubular wall is segmented by longitudinal cuts that extend partially or fully through the wall thickness, creating discrete flex elements. This segmentation allows the wall to bend and flex without requiring increased overall thickness, as the cuts provide the necessary compliance. The flex elements maintain sufficient strength through their geometry and material properties while allowing reduced wall thickness compared to a solid tube.
Solution Approach 2:
The flexible region utilizes thin-walled structures with circumferential flex elements that can bend and deform elastically under torque loading. The bridging portions connect these thin flex elements, providing structural support while maintaining overall flexibility. This approach allows the use of thinner walls that would not be sufficient in a rigid structure but are adequate when configured as flexible elements with appropriate geometry.
3Strength
If the annular wall thickness is increased to maintain strength during torque transmission, then the torque transmission capability is improved, but the internal diameter decreases affecting aspiration efficiency
Solution Approach 1:
Longitudinal cuts segment the tubular wall to create flex elements, allowing the structure to achieve the necessary flexibility without increasing wall thickness. This segmentation enables the maintenance of a larger internal diameter while providing sufficient strength through the geometric configuration of the flex elements and their connections via bridging portions.
Solution Approach 2:
The flexible region employs thin-walled construction with circumferential flex elements that provide the necessary mechanical strength for torque transmission despite reduced wall thickness. This thin-walled design preserves a larger internal diameter for efficient aspiration while the flex elements and bridging portions ensure adequate structural integrity during rotation and cutting operations.
4Strength
If additional structural components are added to the flexible region, then the torque transmission and flexibility are improved, but the manufacturing costs and operational reliability decrease
Solution Approach 1:
The flexible region is integrated into the tubular body as a single piece with cuts formed directly in it, eliminating the need for separate flexible components and their associated assembly operations. This merging of the flexible region with the tubular body reduces manufacturing steps, lowers costs, and improves reliability by eliminating potential failure points at interfaces between separate components.
Solution Approach 2:
The tubular body is segmented by forming cuts directly in it during manufacturing, creating the flexible region in one integrated process. This segmentation approach allows the flexible elements to be created as part of the tubular body itself rather than as separate components requiring assembly, simplifying manufacturing and reducing costs while maintaining the necessary flexibility and strength.
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 enhances structural simplicity, reduces material and manufacturing costs, provides resistance to longitudinal stretching, and enables effective torque transmission across a broad range of bend angles, while preserving the internal diameter and minimizing external diameter, thus improving operational reliability and efficiency.
Implementation Method 1
The flexible region comprises longitudinally and rotationally offset partial circumferential cuts formed in a tubular body of the inner member
Data Source
AI summary
A flexible inner member for being rotatably disposed in an angled outer tubular member of a rotary tissue cutting instrument has a flexible region composed of a series of partial circumferential cuts formed through the wall of a tubular body of the inner member. Each cut extends along an arc that defines part of the external circumference of the tubular body. The cuts are uniformly longitudinally spaced in succession along the length of the tubular body corresponding to the flexible region. The cuts are parallel to one another and perpendicular to a central longitudinal axis of the tubular body. The cuts are grouped in duplicative patterns that repeat along the length of the flexible region, there being at least two successive cuts in each pattern. The cuts of each pattern are rotationally offset in succession in a rotational direction about the central longitudinal axis of the tubular body.