Steerable Bone Cutter with Segmented Stiffness
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Solution Overview
Problem
Conventional bone-cutting tools are either rigid and straight, requiring large incisions for access, or flexible but insufficiently stiff to modify and sculpt bone effectively during orthopedic procedures.
Innovation Solution
A medical device featuring a flexible tubular member with a lumen and a rotatable shaft, steerable by control wires, which maintains stiffness of at least 5 N/mm in a bent position, allowing for precise positioning and cutting of bone surfaces while minimizing tissue damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rigid and straight tools are used to cut bone, then cutting effectiveness is improved, but incision size and tissue damage increase
Solution Approach 1:
The tool is divided into multiple sections along its length, with each section capable of independent bending. This segmentation allows the proximal sections to flex for access while the distal section near the cutting tool remains relatively straight and stiff for effective bone cutting, thus resolving the contradiction between flexibility for access and rigidity for cutting effectiveness.
Solution Approach 2:
Different sections of the tool have different mechanical properties. The proximal sections are designed with lower stiffness to allow bending and navigation through tissue, while the distal section is designed with higher stiffness to maintain rigidity for effective bone cutting. This local differentiation of mechanical properties resolves the contradiction between flexibility and cutting effectiveness.
2Adaptability or versatility
If flexible tools are used to access hard-to-reach surfaces, then accessibility is improved, but stiffness and cutting capability deteriorate
Solution Approach 1:
The tool is divided into multiple sections with varying degrees of flexibility. The proximal sections are more flexible to navigate through tissue and reach hard-to-access surfaces, while the distal section maintains sufficient stiffness to support the cutting tool and enable effective bone modification. This segmentation resolves the contradiction between flexibility for accessibility and stiffness for cutting capability.
Solution Approach 2:
The tool's flexibility is dynamically controlled through its segmented structure, allowing it to bend in proximal sections for navigation while maintaining rigidity in the distal section for cutting. The ability to selectively flex different portions of the tool resolves the contradiction between needing flexibility for access and stiffness for cutting performance.
3Measurement precision
If the tubular member is made flexible to navigate anatomy, then positioning precision is improved, but structural stability deteriorates
Solution Approach 1:
The tubular member is segmented into multiple sections with different mechanical properties. Proximal sections are more flexible to navigate anatomical structures and achieve precise positioning, while the distal section is stiffer to maintain structural stability and prevent unintentional bending during bone cutting. This segmentation resolves the contradiction between flexibility for positioning precision and stiffness for structural stability.
Data Source
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AI summary
A system for cutting a bone of a patient may include a motor; a rotating shaft drivingly coupled to the motor; a support tube positioned around the rotating shaft and supporting the rotating shaft at a plurality of locations; a plurality of steering wires coupled to the support tube; and a bone cutter at a distal end of the rotating shaft.