I was diagnosed for Scoliosis when I was 12, and I went to see an Orthopedic Surgeon. Don't let their title fool you - the fact that they're a surgeon doesn't mean they see surgery-only patients. I've never had an oporation for my scoliosis, and I've always seen and Orthopedic surgeon.
Yes, an orthopedic surgeon. If the patient is under 18, go to a pediatric orthopedic surgeon. If 18 or older, try to find a doctor who specializes in adult scoliosis, and preferably, one who has done a fellowship.