Expandable Fusion Device In Situ Spinal Stability
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Solution Overview
Problem
Conventional intervertebral fusion devices require vertebral body distraction for installation, making it difficult to maintain normal disc spacing and restore spinal stability without additional height differences.
Innovation Solution
An expandable fusion device with a central ramp and endplates that can be expanded in situ, allowing for placement at minimal distraction height and maintaining normal disc spacing through a ratcheting mechanism for adjustable expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional fusion devices are used, then vertebral bodies can be fused together, but the devices require pre-distracting the vertebral bodies to installation height, creating additional complexity and potential complications
Solution Approach 1:
The fusion device incorporates an expandable structure that transitions from a compressed delivery configuration to an expanded installed configuration. The device includes expandable cage bodies with movable endplates that can be distracted apart to increase the height of the device after insertion, eliminating the need for pre-distraction of vertebral bodies to the final device height
Solution Approach 2:
The fusion device is divided into separable components including first and second endplates that can move relative to each other, and expandable cage bodies. These segmented components allow the device to be inserted in a compressed state and then expanded to the desired height, simplifying the installation procedure by avoiding the need to maintain distraction at the target height during insertion
2Shape
If vertebral bodies are distracted to restore disc space height, then normal disc spacing can be maintained, but the height difference between distracted and device height makes installation difficult
Solution Approach 1:
The device is pre-compressed to a delivery configuration that is smaller than the final installed height, allowing insertion through the disc space without requiring pre-distraction to the final height. The compression is performed beforehand during device preparation, enabling easy insertion followed by expansion to the target disc spacing
Solution Approach 2:
The device transitions dynamically from a compressed insertion state to an expanded maintenance state. The expandable structure allows the device to be inserted at minimal height and then expanded in situ to maintain normal disc spacing, resolving the conflict between ease of installation and maintenance of proper disc geometry
3Ease of operation
If fusion devices are inserted without expansion capability, then installation is simpler, but the devices cannot maintain normal disc spacing without pre-distracting to larger heights
Solution Approach 1:
The fusion device incorporates expandable mechanisms including movable endplates and expandable cage bodies that allow the device to increase in height after insertion. This dynamic capability enables the device to be inserted in a compressed state for ease of installation and then expanded to maintain normal disc spacing, simultaneously achieving both ease of operation and proper disc spacing maintenance
Solution Approach 2:
The expandable structure acts as an intermediary mechanism between the inserted device and the vertebral bodies. The device can be inserted without significant distraction and then the expansion mechanism mediates the increase in height to achieve proper disc spacing, eliminating the need to distract to the final height before insertion
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
Enables efficient installation and maintenance of normal disc spacing without pre-distracting vertebral bodies, facilitating intervertebral fusion while allowing for adjustable expansion to restore spinal stability.
Implementation Method 1
The central ramp may be capable of moving in a first direction to push the first and second endplates outwardly and into an unexpanded configuration
Data Source
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AI summary
The present invention provides an expandable fusion device capable of being installed inside an intervertebral disc space to maintain normal disc spacing and restore spinal stability, thereby facilitating an intervertebral fusion. In one embodiment, the fusion device includes a central ramp, a first endplate, and a second endplate, the central ramp capable of being moved in a first direction to move the first and second endplates outwardly and into an expanded configuration. The fusion device is capable of being deployed down an endoscopic tube.