Expandable Interbody Cages With Nested Screw-Driven Expansion
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Solution Overview
Problem
Existing spinal fusion devices face challenges in minimizing surgical trauma while allowing for the use of larger implants due to the limitations of access ports, necessitating the development of expandable interbodies that can be inserted through small access ports and expanded in situ to provide adequate support and fusion.
Innovation Solution
The design of expandable interbodies with superior and inferior shells and a control assembly that allows for expansion or contraction, utilizing angled channels and adjustment screws to translate relative movement between cages, providing structural support and promoting bone growth through porous materials and graft windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a small access port is used to minimize surgical trauma, then patient trauma is reduced, but the size of tools and implants that can pass through is limited
Solution Approach 1:
The interbody device is designed to be expandable, transitioning from a compressed insertion state to an expanded functional state. The device includes expansion members that can be actuated to increase the interbody's dimensions after insertion through a small access port, allowing minimal invasive surgery while achieving the required implant size for adequate support and fusion.
Solution Approach 2:
The interbody device is divided into multiple components including superior and inferior shells, expansion members, and control mechanisms. This segmentation allows the device to be assembled and inserted in a compact form, then expanded in situ to achieve the desired size for spinal support and fusion.
2Strength
If traditional non-expandable interbodies are used, then the implant size is fixed and adequate support is provided, but the access port size must be large which increases surgical trauma
Solution Approach 1:
The interbody device transitions from a static non-expandable design to a dynamic expandable design. The device is inserted in a compressed state through a small access port and then expanded to provide adequate structural support, combining the benefits of minimal invasive surgery with sufficient implant size for spinal fusion.
Solution Approach 2:
The interbody device is pre-compressed to a small size for insertion through a minimal access port, then expanded in situ to achieve the required size for structural support. This preliminary compression allows passage through small openings while maintaining the ability to provide adequate support when deployed.
3Object-affected harmful factors
If expandable interbodies are designed to be inserted through small access ports, then surgical trauma is minimized, but the device complexity increases
Solution Approach 1:
The interbody device is segmented into superior and inferior shells with integrated expansion members and control mechanisms. This segmentation allows for a manageable complex structure that can be compressed for insertion and then expanded, balancing the need for minimal invasive surgery with the required functional complexity.
Solution Approach 2:
The expansion members and control mechanisms are merged with the superior and inferior shells to form an integrated expandable interbody device. This merging reduces the number of separate components and simplifies the overall structure while maintaining the expandable functionality for minimal invasive insertion and deployment.
Data Source
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AI summary
The present disclosure relates to expandable interbodies that include superior and inferior shells and a control assembly positioned between and inside of the shells, the control assembly including nested cages operably connected to each other with an adjustment screw. Rotation of the adjustment screw translates the cages relative to each other, which in turn causes the shells to open or expand.