Expandable Interbody Implant Wedge Locking Mechanism
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Solution Overview
Problem
Existing expandable interbody implants face issues with over-expansion, disassembly, and inadequate locking mechanisms, leading to instability and potential collapse under spinal load.
Innovation Solution
The design incorporates a threaded post between opposing wedges that expands the implant in at least one plane, with aligning supports and connectors to prevent rotation and over-expansion, and a locking mechanism to secure the expanded position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple angled grooves, rails, or dovetails are used to prevent endplates from falling off, then the device structure becomes more complex, but the device still cannot prevent over-expansion or disassembly
Solution Approach 1:
The device is divided into multiple components including endplates, wedges, and connectors that can be assembled together. The connectors are configured to engage with both the endplates and the threaded post, creating a segmented structure that prevents over-expansion while maintaining ease of assembly
Solution Approach 2:
The connectors serve as intermediary elements between the endplates and the threaded post. These connectors transmit the expansion force while simultaneously preventing the endplates from separating or over-expanding, resolving the contradiction between reliability and complexity
2Adaptability or versatility
If the device is made from a plurality of smaller components, then the device can be more adaptable, but the overall device integrity is compromised as smaller pieces are weaker
Solution Approach 1:
Multiple functional components (endplates, wedges, connectors) are merged into a single integrated assembly that maintains overall structural integrity. The connectors fuse the endplates to the threaded post, creating a unified structure that is both adaptable and strong
Solution Approach 2:
The device utilizes composite construction with different materials for different components - the threaded post and connectors are made from stronger materials while the endplates can be made from lighter materials, achieving both adaptability and overall integrity
3Device complexity
If exterior pressure is used to prevent rotation of the anterior wedge, then the device can be simpler, but the implant binds and requires more force to expand
Solution Approach 1:
The threaded post and connectors are designed to automatically prevent rotation of the anterior wedge during expansion. The threaded connection creates self-aligning features that guide the wedges together without requiring external pressure or additional components, eliminating binding while maintaining simplicity
4Device complexity
If no locking mechanism is used to secure the expanded position, then the device is simpler, but the device collapses under spinal load
Solution Approach 1:
The threaded post is pre-configured with threads that engage with the connectors before expansion occurs. As the wedges are compressed together during installation, the threaded connection automatically locks the endplates in their expanded position, providing preliminary locking action that prevents collapse under spinal load
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 configuration maintains alignment of endplates, prevents unwanted rotation of wedges, and ensures the implant remains stable and locked in its expanded position, addressing issues of over-expansion and disassembly.
Implementation Method 1
a threaded post disposed between a pair of opposing wedges directs the wedges closer together as the threaded post is rotated to drive movable endplates operably engaged with the wedges radially outward from a longitudinal axis of the threaded post
Implementation Method 2
the aligning support comprises one or more rails adapted to engage with and prevent rotation of the wedges
Implementation Method 3
One or more connectors may run through the elongated connector slots and into each wedge, to secure the endplates to the wedges. These connectors, for example, pins, may allow the endplates to move along the wedge faces
Implementation Method 4
a locking mechanism, for example, a set screw may be threaded into a posterior portion of the second wedge (e.g. the posterior wedge) and against the threaded post, which may prevent the threaded post from counter-rotating
Data Source
AI summary
The present invention generally relates to an expandable interbody implant. Specifically, the present invention is an expandable interbody implant having an anterior and posterior wedge and opposing endplates. In some embodiments, a slot parallel to the wedge face may be located on each endplate, with a pin holding the endplates to the respective wedges. Additionally, in some implementations, lateral rails may extend from the anterior wedge to the posterior wedge. Furthermore, the expandable implant may include a locking mechanism configured to prevent unwanted collapse.