I'm sorry for you little one's trouble.
LP is diagnosed in stages 1-4 or 5 I believe. We had a Yorkie once with stage 1 or 2. The vet told us she could have surgery or it may be that she would live her whole life without it troubling her. She was fine. You can do a search right here on this forum to find out how others have handled it. My prayers are with you and Roxie.
Jackie & my 
Sophie 