Expandable Spinal Cage with Linked Locking Mechanism
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Solution Overview
Problem
Conventional spinal implants fail to effectively expand and distract vertebral end plates, leading to poor interface between bone and biomaterial, resulting in nonunion and 'flatback syndrome' due to lack of resistance to movement and inadequate space for neural elements.
Innovation Solution
A spinal implant with a contracted configuration for easy insertion and an expandable configuration, featuring extendable support elements and a locking system that mechanically engages to lock the implant in place, using hydraulic or mechanical means to adjust and stabilize vertebral positions, thereby providing controlled spinal correction in three dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a static spacer is used for interbody stabilization, then the device is simple to insert, but it cannot expand to effectively distract end plates and provides poor interface between bone and biomaterial
Solution Approach 1:
The implant transitions from a static configuration during insertion to a dynamically expandable configuration after placement. The expandable cage can be adjusted post-insertion to optimize distraction force and interface stability, resolving the contradiction between ease of insertion and interface stability.
Solution Approach 2:
The implant uses a nested structure where the cage expands from a compact inserted state to a larger stabilized state. The locking mechanism nests within the cage structure, allowing the device to maintain simplicity during insertion while providing complexity for stable fixation after placement.
2Device complexity
If conventional static spacers are used, then the device structure is simple, but it cannot maintain interbody lordosis and contributes to flatback syndrome
Solution Approach 1:
The expandable cage allows dynamic adjustment of the implant's height and angle after insertion, enabling maintenance of interbody lordosis and prevention of flatback syndrome while keeping the base structure relatively simple.
Solution Approach 2:
The implant enables change in geometric parameters (height, angle, expansion ratio) after insertion to maintain proper spinal alignment and lordosis, resolving the contradiction between structural simplicity and alignment maintenance capability.
3Device complexity
If static cages are used, then the implant is simple, but it does not reliably improve space for neural elements
Solution Approach 1:
The expandable cage can be adjusted post-insertion to optimize the intervertebral space height, reliably improving space for neural elements while maintaining a relatively simple base structure that expands as needed.
4Ease of manufacture
If conventional static spacers are used, then the device is simple to manufacture, but it forms a weak interface between bone and biomaterial due to poor resistance to movement
Solution Approach 1:
The expandable cage allows for post-manufacturing adjustment to optimize the interface strength between bone and biomaterial. The simple manufacturing process is maintained while the expandable feature enables strong fixation through controlled distraction and locking.
Data Source
AI summary
A spinal implant which is configured to be deployed between adjacent vertebral bodies. The implant has at least one extendable support element with a refracted configuration to facilitate deployment of the implant and an extended configuration so as to expand the implant and effectively distract the disc space, stabilize the motion segments and eliminate pathologic spine motion. The implant has a minimal dimension in its unexpanded state that is smaller than the dimensions of the neuroforamen through which it typically passes to be deployed within the intervertebral space. The implant is provided with a locking system having a plurality of linked locking elements that work in unison to lock the implant in an extended configuration. Bone engaging anchors also may be provided to ensure secure positioning.