My opinion is in my blog. I think they submitted 2 devices late 2016 based on whats described in 10k.
There's this:
In December 2016, we re-filed an FDA 510(k) submission for clearance in the United States of a modified novel composite spinal fusion device that combines porous and solid silicon nitride, and obviates the need for bone grafts that is comparable to our commercially-available Valeo®C cervical implants.
This is Valeo C + CsC with Lumen (hole). Solid Si3N4 otter shell, porous center with a small hole to pack bone into.
Then there is this:
We have since re-filed a 510(k) premarket application with the FDA, for a modified CsC-based cervical implant that is comparable to our own commercially-available Valeo®C cervical implants.
Amedica 2016 10k pg 12
To me there are 2 different devices pending and 1 is the composite we are familiar with and the other is a porous Valeo C with no solid portion which is like Zimmers Ardis TM device. This is the device I believe the LOI is referencing.