I had a very similar situation. I had anterior surgery at 15 and my parents were torn about which surgery to have; however, my mother felt so much better about me being able to bend after surgery. I have friends who have had posterior and basically they are as straight as a board and can't bend anywhere but at the waist. Having done a little golf myself, I can tell you that it will be hard for your son to play if he has the posterior. I'm very happy with my anterior surgery. I just went to the doctor this past week, and 5 years post op I'm doing very well. They are watching a curve that is below my fusion (about 20 degrees) and if it gets a lot worse then my doc will have to go down below my fusion and little above it. But he doesn't anticipate that having to happen. However, it would be nothing like posterior. I understand that you only want your son to have one surgery but there's a great chance that anterior will be the only surgery he has and he'll be fine after. Not many people have the option of anterior and if you pass it up, then you might be doing your son a disfavor by making him rigid. So I would go for it. I know that I do not regret my families' decision one bit. I had a great result and my curve that was fused is only 6 degrees now. I don't know what your doc has said about having posterior but it will fuse vertebrae from the very nape of his neck to his tailbone. I think it's about 13 vertebrae. I've only had 3 fused. Physically, I look great and my scar is so thin and very light. No one can tell that I have any problems. As far as my scar compared to posterior fusions, my scar is thinner and isn't as noticeable when I have a bathing suit on. I don't know how your son will feel when he is 50 or 60. I don't think anyone will be able to answer that. As far as surgery goes, the anterior surgery is harder to endure and possibly more painful because the docs go in from the side and remove a rib (which was the most painful part for me) and have to get around the internal organs. But I think it was worth it. I actually go to school in St. Louis at Wash U and I've heard of Dr. Bridwell because my doc, Dr, Hanson, in Houston, where I'm from , did his residency at Barnes. My surgery was done by Dr. David Bradford in San Francisco, who is the best in the field. If you have a chance to see someone else,then you should go see him. Every doc knows he is the best. My parents took me to Dallas to see Dr. Herring and then to Dr. Bradford. If it were my son, I'd give him the chance to play golf again and bend like he wants to by having the anterior surgery. There is a slight chance that he might have to have more fused later on in life but at least you will know that you gave him the opportunity to be an active teen. Posterior can have problems as well so both surgeries are risky. This is going to be a really rough time in your life but once you get past it all, you and your son will be much stronger as people. I know that I would never take back what I went through regardless of how difficult it was. I'm a much better person today because of it.
Others may not agree with me. I'm being very honest here. I tend to have a strong opinion and I hope that doesn't bother you. I just know that this is a difficult time for you and you need to hear the truth (or what I believe is to be true). I agree that it is imperative that your son have surgery now. I think he's a very lucky guy since he qualifies for anterior. Good luck and keep us updated.