Thank you GKTM300 for pushing me in the right direction!
I'm currently in contact with three European doctors - Clavel, Ritter-Lang and Bertagnoli - to get their individual opinions. I have only heard back from Bertagnoli so far regarding a final opinion. He says that I have degenerative disc disease in addition to the retrolisthesis and herniation at the L5-S1 level. He is recommending the ADR surgery.
I will be meeting with my first American surgeon on Monday, followed by two more later in the month to get more opinions.
I am very concerned with having a facet issue after the surgery due to the retrolisthesis. My worst fear is that it does not correct it and I need to have a revision surgery, or at worst a fusion