Sorry, I can'd give you any advice, but I can tell you what these medical words mean. Spondlolsis, is a spinal disorder in wihch the arch of the 5 th vertebra consists of soft fibrous tissue instead of normal bone. Spondylolisthesis is a (forward) or(backward) of L5 over S1 in your case. Does your Dr. want to do surgery? I would just ask, if I were you. If you are in a lot of pain, this is probably why. I am not a doctor, so I can't tell you.
Good Luck and keep us informed.
Fancylady