Fusion is known to bring all sorts of problems post surgery. It is not a great option, just the only option till ADR was developed (back in the 1980's, I believe). ADR is trending towards the preferred choice for the spine of the two due to the lesser pressure put on the surrounding discs, which puts them at risk over time. Fusion also limits mobility from day one after the surgery, whereas ADR does not.I mean if we want to be real, the issue here is that Eichel is refusing to get the standard surgery for his neck and wants specifically the disc replacement surgery. Eichel's "bad neck" is only an issue because Eichel wants an "experimental" surgery. And by "experimental", I mean something that NHL players haven't done before.
It's Eichel's right to demand whatever surgery he wants, but this issue would have been resolved months ago had Eichel just been willing to take the existing surgery that is proven to work.
To sum up, fusion "works" after a fashion, but ADR was developed as an improvement, not as a lesser option to fusion. All surgeries come with risks, but pretending that ADR is fraught with them and fusion is safer is flat out wrong.