Well, to be perfectly honest the first 72 hours aren't wonderful. You are really in a lot of pain at the beginning. For me it was a different pain though. All of my pre-surgery pain was gone, and was replaced by the pain from all the work my surgeon did. I don't remember a whole lot because of all the narcotics I was on, but I'll do my best to help you out!
I was in the hospital for four days. I woke up on my back, without my brace. I was hooked up to a PCA pump with morphine (thank goodness for that!) and I had a catheter, as well as an IV with antibiotics and something else (fluids I think). I remember using the pump a lot, but sometimes it just didn't control the pain and then the nurse would give me something else for breakthrough. I was sick to my stomach a lot during my hospital stay, because of all the narcotics. They got me up the first morning after surgery, and that was not a lot of fun. I couldn't believe they were making me get up less than 12 hours after surgery (I didn't get out of recovery until around 11:30 PM because my surgery lasted almost 7 hours). I had my brace on when I was up, and I did manage to walk a little bit using a walker. I'm not going to lie, it hurt, but now I'm glad they made me do it. After that, I was up a little bit more each day. I was only on the PCA pump for 2 days (maybe 3- not sure), and then they switched me to only oral meds. I started using the bathroom myself after the second day, so that's when they took the catheter out. By the time I went home (on day 4) I was able to dress myself, climb stairs, and walk fairly well with the walker. I think my hospital stay was pretty short for a fusion, but I was really motivated to get out of there.
I hope this helped. Good luck with your surgery! Please keep us posted when you can!