Expandable Fusion Implant With Deployable Spikes for Expulsion Resistance
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Solution Overview
Problem
Existing expandable fusion devices for spinal surgery lack effective anti-expulsion features, particularly in procedures where the anterior longitudinal ligament is released, increasing the risk of the device being expelled from the disc space.
Innovation Solution
The development of an expandable fusion device with integrated deployable retention spikes that deploy from the implant body to resist expulsion, along with the ability to communicate implant information with robotic and/or navigation systems for precise placement and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the anterior longitudinal ligament is released to facilitate decompression and fusion, then the surgical access and decompression are improved, but the risk of implant expulsion from the disc space increases
Solution Approach 1:
The implant is divided into separate functional components: a main body for structural support and deployable retention spikes for preventing expulsion. This segmentation allows the implant to address both the need for surgical access (through the main body) and the need for secure retention (through the deployable spikes) without compromising either function.
Solution Approach 2:
The retention spikes are designed to be deployable rather than fixed, allowing them to transition from a retracted state during insertion to an extended state for providing retention. This dynamic feature enables the implant to adapt to different operational phases, providing secure retention only when needed while maintaining ease of insertion.
2Adaptability or versatility
If a hyperlordotic expandable cage with high adjustability is used to restore sagittal balance, then the corrective capability is improved, but the risk of anterior expulsion due to increased axial forces increases
Solution Approach 1:
The implant separates the adjustability function (main body) from the retention function (deployable spikes). This allows the main body to provide high lordotic adjustability for sagittal balance restoration while the deployable spikes independently provide anti-expulsion capability, resolving the contradiction between adaptability and reliability.
Solution Approach 2:
The deployable retention spikes provide preliminary anti-action against expulsion forces before they can cause failure. By deploying the spikes in advance or upon insertion, the implant preemptively counteracts the increased axial forces that could otherwise expel the hyperlordotic cage, allowing high adjustability without compromising retention.
3Ease of operation
If the natural barrier (anterior longitudinal ligament) is removed to access the disc space, then the decompression is improved, but the protection against anterior expulsion is lost
Solution Approach 1:
The deployable retention spikes serve as an intermediary protective feature between the implant and the expulsion forces. Since the natural barrier (anterior longitudinal ligament) has been removed to facilitate access, the spikes provide a substitute protective mechanism that mediates against the harmful expulsion forces, allowing safe access while maintaining protection.
Data Source
AI summary
Expandable fusion devices, systems, and methods. The expandable fusion device includes one or more integrated deployable retention spikes configured to resist expulsion of the device when installed in the intervertebral disc space. The implant may include upper and lower main endplates, an actuator assembly configured to cause an expansion in height of the upper and lower main endplates, and a sidecar assembly including a sidecar carrier, an upper carrier endplate engaged with an upper spike, and a lower carrier endplate engaged with a lower spike such that forward translation of the sidecar carrier pushes against the upper and lower carrier endplates, thereby deploying the upper and lower spikes.