Flexible Guide Rod Asymmetry for Bone Screw Manipulation
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Solution Overview
Problem
Flexible fastening devices, such as bone screws and reamers, often twist and deform or break when rotated, especially in medical applications, due to angular deformation, leading to difficulties in insertion, removal, and manipulation.
Innovation Solution
A system featuring a flexible guide rod with a D-shaped cross-section that engages with a complementary interior channel in the rotational device, allowing minimal rotation (less than 10 degrees) and preventing complete rotation, thereby reducing deformation and breakage, and facilitating insertion, removal, and adjustment of screws and reamers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flexible fastening device is rotated for insertion or manipulation, then the device can be inserted into curved passages or bone cavities, but the device twists and deforms or breaks due to angular deformation
Solution Approach 1:
The guide rod is given an asymmetric D-shaped cross-section instead of a symmetric circular cross-section. This asymmetric shape engages with the complementary asymmetric interior channel of the fastening device, preventing rotational movement while allowing the flexible device to be inserted into curved passages without twisting or breaking
2Ease of operation
If a guide wire is used to align fragments and provide a path for canal enlargement tools and screw, then the path can be established through fractured bone, but the screwdriver rotates with the guide wire causing misalignment and insertion difficulties
Solution Approach 1:
The D-shaped guide rod with asymmetric cross-section engages with the complementary asymmetric interior channel, creating a mechanical constraint that prevents rotation. This asymmetric engagement maintains precise alignment between the guide rod and fastening device throughout insertion, eliminating the rotation problem associated with circular guide wires while requiring no additional rotation control mechanisms
Data Source
AI summary
A system for manipulating a rotational device using a flexible guide rod with an external rod feature along its length to engage a rotational device with a complementary interior channel feature along its length. A driver having a handle and coupling element is coupled to the rotational device while the flexible guide rod extends from the handle, through the coupling element, and into the interior channel of the rotational device in order to rotate from within along the length of the device.