Unfortunately, it's one of those things that you know the risks in the back of your head but it's better to not dwell on it unless you have to cross that bridge.
I don't know why your DH is having back surgery. If it makes him feel better my DD had to have spinal fusion last year for scoliosis. She has 2 rods & 23 screws in her back now but other than never playing football or tumbling, she will be able to go back to normal. She should get the green light at her 1 year post-op to go on roller coasters.
Her recovery was a bit difficult but that was only because the pain meds made her sick since she didn't want to eat but if you don't eat, it makes you sick to your stomach -- so you see the cycle we got into. It was like having a toddler with an attitude during recovery but by the time her 7 weeks were up & she could go back to school, we were both ready for her to get out of the house.
She ended up doing an acting performance at about 8-9 weeks out since she was an understudy & the person who was to play a part wasn't allowed back in school (that was when the new restrictions for H1N1 had been put in place). Six months after surgery she was on stage doing her first pageant.
Other than the scar on her back and her restrictions, you would never know she had the surgery.
Hopefully this will ease some of the fear.
Wow, Becky, I almost could have written this post myself! My DD had scoliosis surgery a little over 8 weeks ago, and except for her scars, and a little stiffness, you would never know she had anything done. Her recovery sounds very similar to your DD's; it did feel like having a toddler again! I had to help her dress, shower, use the bathroom, etc., and we would cheer her little milestones like we did when she was little, "Yea! She sat up by herself! Yea, she rolled over! Yea, she's walking!". But now, she's almost completely back to normal, and it's wonderful! In fact, I think my DD recovered a bit faster, because she was back in school full time 5 weeks post-op, and has been cleared to resume all non-jarring activity. Her surgeon says she will be able to ride roller coasters when we go to Disney in June.
I did make sure to stay off the internet as much as possible in the days leading up to her surgery, though. I tried to find mostly success stories, and sites that rationally outlined the risks. I purposely avoided anything negative; her curve was 63 degrees on top, and 90 degrees on bottom, and she definitely needed the surgery!!! We really had no other choice. Reading horror stories, or sites that claim they had better treatment than "debilitating" surgery was not going to be helpful, so I didn't. We were in expert hands, and everything turned out great.
So, OP, there's another success story for you!