Reaming Tool with Offset Connecting Piece for Trapezium Bone
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Solution Overview
Problem
Existing tools for reaming the trapezium bone during thumb joint prosthesis implantation face challenges in achieving central and straight reaming, which can lead to suboptimal cup fitting and increased tissue pressure, complicating the implantation process.
Innovation Solution
A tool with a head and handle aligned along an axis, featuring a connecting piece that extends around the thumb, allowing for straight-on reaming of the trapezium bone without significant thumb displacement. The tool includes a rasp on its outer surface and a spherical head for accurate cup fitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thumb is pushed aside and the trapezium bone is approached at an angle with conventional tools, then access to the trapezium bone is achieved, but central and straight reaming becomes difficult and tissue pressure increases
Solution Approach 1:
A connecting piece is introduced as an intermediary element between the handle and head of the reaming tool. This connecting piece extends around the thumb, allowing the handle and head to be positioned straight in front of the trapezium bone without requiring the thumb to be pushed aside. The intermediary connecting piece enables straight-on approach while avoiding collision with the thumb, thereby achieving both central/straight reaming precision and ease of operation
Solution Approach 2:
The connecting piece is positioned at a distance from the axis between the head and handle, creating a three-dimensional configuration that allows the tool to approach the trapezium bone from a straight direction while the connecting piece extends around the thumb in another dimension. This spatial arrangement resolves the conflict between achieving straight reaming and avoiding thumb collision
2Reliability
If the thumb is pushed aside to access the trapezium bone, then reaming can be performed, but the cup fitting becomes suboptimal and tissue pressure increases
Solution Approach 1:
The connecting piece acts as a mediator that enables straight-on reaming without displacing the thumb. This straight approach ensures the cup fits optimally in the reamed trapezium bone and prevents excessive pressure on surrounding tissues, thereby improving cup fitting quality and reducing harmful tissue pressure simultaneously
Data Source
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Figure 3~3A
AI summary
Tool (1) for reaming a trapezium bone (2) when implanting a joint prosthesis (15, 16, 17) in the thumb (4), in which the tool has a head (5) and a handle (6) which extend along an axis (7), in which a connecting piece (8) is provided between the head and the handle, which connecting piece lies at a distance (9) from the axis in such a way that when rotating the head back and forth (13) using the handle the connecting piece moves at a distance from the thumb while the axis runs through the thumb.