I have no advise either on the Rhizotomy. However, I do know that after that surgery, the physical therapy is VERY instense.....

My Megs had her 1st adductor release on her left hip when she was 14 mos old. She was in a spica cast for 6 weeks. It was not completely out of socket either. A few years later she had the right hip done, same thing, long leg casts with bar in between for 6 weeks. For Megan it was a very minimal surgery, very little pain. Had the usual discomfort any of us would have in a cast. Her hips have been ROCK solid ever since. She has had no further hip issues. Good luck in your search. If you ever have any questions feel free to ask.
Tracy