Squats with safety bar

Reverse hyper extensions saved Loiuse Simmons career after he buggered his back a few decades ago.
I’d suggest only back exercises that allow you to lay down for now.

If you don’t have reverse hyper machine, do oyou have a very sturdy box/apparatus/bench where-by you can grab something with 90+ degree elbow bend, whilst your lowerback/glutes/hams take resistance at the other end? Atatch resistance to ankles. (usually stretch bands/bungee cord type resistance if u don’t have a machine.)