I have a little experience in this area (as the patient). When it comes to back surgery, they really really really don't want to do it if they can. It's a lot more delicate than trying to fix a leg because it is the spinal cord. Obviously the route of doing it without surgery failed.
Honestly, I'm not counting on him being back and as good as before basically ever. If he is, I'll be happily surprised.
Edit: for the avoidance of doubt… I think now we know why, despite having 5 center backs already for only two spots on paper next year, we started looking for a center back a few weeks ago.
Edit2: He posted this to instagram; it looks like he's on one of those beds that kind of inflate and deflate parts automatically so he doesn't get bed sores; I wonder how much he's able to move his legs right now.
https://www.instagram.com/p/DYXLDaLtOEv/?igsh=MWI1Z2tka2NzNGRubA==