My girlfriend was in the same position after several failed spinal surgeries. I think you really want to find a good surgeon to do this as the operation, as described to me by my girlfriend, is quite delicate.
In general with surgery you want to find someone who does the operation you're looking for alot - so look for very experienced surgeons. My girlfriend also uses physician reviews to scout out surgeons. She also asks her doctors about their recommendations. You might also want to get in touch with heads of departments in academic centers and get their opinion.