My dad has DDD, stenosis, osteoarthritis of the spine and Parkinson's
In his mid 70's.
Unfortunately they haven't found a way to rebuild /replace the whole spine yet.

Have they mentioned trying a TENS, or possibly a SCS trial?

SCS is a implanted & stronger version of a electronic pain signal blocker.

WE have a SCS sub forum here-
http://neurotalk.psychcentral.com/forum118.html

There are also implanted pain pumps that can deliver the meds right to the spinal fluid.

My dad might be looking into these options at some point.