Expandable Implant Ratchet Block Position Switching
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Solution Overview
Problem
Conventional expandable corpectomy devices using a rack and gear assembly often skew during expansion and lack a mechanism to turn off the ratchet, making it difficult to collapse or remove the device once expanded.
Innovation Solution
An expandable implant with a base, extension arm, and a ratchet block that can move between two positions, allowing upward movement and selectively preventing downward movement to prevent unwanted collapse, enabling controlled expansion and collapse for repositioning or removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ratchet mechanism is used to prevent unwanted collapse, then the device maintains stability after expansion, but the device cannot be collapsed for removal or replacement
Solution Approach 1:
The ratchet block is made movable between a first position (blocking downward movement) and a second position (allowing downward movement). This dynamic configuration allows the device to transition from a stable, locked state after expansion to a collapsible state for removal or repositioning, resolving the contradiction between reliability and adaptability.
2Device complexity
If a single rack and gear assembly is used for expansion, then the device structure is simplified, but the device skews to one side during expansion
Solution Approach 1:
The expansion mechanism is segmented into multiple rack and gear assemblies (first rack and gear, second rack and gear) positioned at different locations. This segmentation allows each component to work independently to expand opposite extension arms simultaneously, preventing skewing while maintaining reasonable structural complexity.
3Reliability
If the ratchet is always engaged to prevent collapse, then the device maintains its expanded position, but the device cannot be repositioned or removed
Solution Approach 1:
The ratchet block's ability to move between engaged and disengaged positions provides dynamic control over the locking function. When in the first position, it maintains the expanded position reliably; when moved to the second position, it allows easy collapse for repositioning or removal, resolving the contradiction between reliability and ease of operation.
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 solution provides a controlled and efficient method for expanding and collapsing the implant, preventing skewing and allowing for easy removal or repositioning by allowing the ratchet block to switch positions, enhancing the usability of the device in spinal surgical procedures.
Implementation Method 1
a ratchet block that is movably disposed between a first position and a second position in the ratchet block cavity. The ratchet block when disposed in the first position allows movement of the extension arm in an upward direction out of the extension arm cavity and blocks movement of the extension arm in a downward direction into the extension arm cavity
Data Source
AI summary
An implant is disclosed. The implant has a base including an extension arm cavity and a ratchet block cavity that intersects the extension arm cavity, an extension arm that is movably disposed in the extension arm cavity, and a ratchet block that is movably disposed between a first position and a second position in the ratchet block cavity. The ratchet block when disposed in the first position allows movement of the extension arm in an upward direction out of the extension arm cavity and blocks movement of the extension arm in a downward direction into the extension arm cavity. The ratchet block when disposed in the second position allows movement of the extension arm both in the upward direction out of the extension arm cavity and the downward direction into the extension arm cavity.