I Was Told That Since My 3 Spinal Shots Of

I was told that since my 3 spinal shots of steroids didn't effect my calf, shin and ankle pain that I need to have DRG therapy. This pain started when I had my knee replaced end of Feb 2016. The spinals relieved it about 50%, but it inhibits my walking (long) and standing Long. (1) The info the Dr gave me does not state what the implant is made of. (2) I can only find evidence of the time this procedure would last is Maximum 1 year.
(3) Then what ?