The type of surgery you will be having is the gold standard when it comes to making sure the area with be as strong as possible when all is healed. It makes sense to do it that way, considering your young age and for how long you will want the results to last.
I too am familiar with the spine clinic you will be going to. Is your scoliosis something they will be dealing with during your surgery?
If you haven't found it already, there is a "stickie" note near the top of the page entitled "Post-Surgery Must-Haves" that is a collection of things others have found useful during recovery from spine surgery. It makes for interesting reading and gets you thinking about what life will be like in early recovery. It includes just about everything -- most of which you will not need, but it does help you get in the right mindset prior to surgery.
More than things you may need is setting up your environment before surgery so it will function for you when you have bending and reaching restrictions. I hope you will have some help for at least the first week or two. Beyond that, it will be convenient if your kitchen and bath are arranged so that things you use often are right at counter height.
I had a posterior fusion from L3 to S1 and some reconstruction at L3 almost two years ago. My doctor believes in using a brace, so I was in it for about 10 weeks (whenever I was out of bed). Do you know if you will wear a brace? It has become pretty much the surgeon's choice with some believing you don't need one because that is the job of the hardware.
You will want comfortable clothes that are easy to slip on and that do not have a tight waistband. I pretty much lived in "yoga" pants and a baggy top. If you do end up with a brace, you may want to stock up on long tank tops as they make the brace more comfortable.
You will be in the hospital for about 3 nights and 4 days and will be discharged when you are able to take care of your basic needs on your own. You will be gotten up and will walk fairly soon post surgery. It is challenging the first few times but it gets easier.
Your pain will be controlled with an IV drip first and probably a mechanism that allows you to push a button as needed. After a period of time, you will be switched to oral meds as they prepare you to be able to go home. You will probably awake from surgery with a catheter. If you've never had one, don't worry about it. It is actually convenient right after surgery as you won't have to ring for the nurse to take you to the bathroom. You won't really notice it and it will be just one more set of lines running in or out of your body. You may also have a small drain for a bit after surgery. All these lines will make walking a bit challenging...also repositioning yourself in the bed, but just remember that it only lasts a day or two and things do get much better fairly quickly.
Once you get home you will be encouraged to take small frequent walks. The main reason for walking early on is to stretch out the spinal nerves. This is very important because you do not want scar tissue to have a chance to attach to a nerve as it is filling in and forming. So plan on taking short walks often, even if it is just around the house. You will be having surgery at a good time as you will be able to go outside to walk. (I live in the frozen northland too and had my first fusion the beginning of January -- bad timing!)
When you are not walking or sitting briefly to eat, you will want to be reclining, with your back supported. Most surgeons limit the time spent sitting to 15-20 minutes at a time. Sitting puts 30% more stress on the discs. Given where you are going to be fused, it is really important that you keep track of your sitting time and pay attention to this limitation.
It will be very important to rest. This is a big surgery and a traumatic event to the body. It takes a lot of energy to grow new bone cells so it is important to rest when you are not taking your walks. Some people find the lack of activity during this phase of healing very difficult. I think it is easier if you are prepared ahead of time. You are not being lazy. This is the time to let others take care of you and to give yourself permission to sleep when tired and to rest. The way I looked at it is the following: you do not want to have to repeat this experience so it is very important to do everything in your power to insure the surgery is successful. Look at the surgery as your primary job for the next 4 to 6 months. Everything you do is devoted to making the outcome a success. Before doing any activity, get in the habit of asking yourself whether the particular activity will help or be potentially harmful...and then, act accordingly. This is the time to be strict with yourself...to take really good care of yourself and make wise decisions.
The first couple weeks will be rough but manageable. You will then find that recovery goes along in spurts -- some days you will feel like you are making progress and then there will be a small setback. I found it worked best to not ask myself every day how I was feeling or progressing as that can be frustrating...but when you look at it over a couple weeks or a month, you will be able to see progress.
There is no way to predict how you will react to the surgery. Even within one person who has more than one surgery, recovery can vary a lot. With my first fusion which was a one level PLIF, I was on pain meds for the first two months...and was pretty laid up. With my recent 3 level fusion, I was off all medication on the 10th day, was moving around pretty well and feeling reasonably good. This makes no logical sense to me...but that's how it was.
All you can do is take it one day at a time and know that by a year from now, this will all just be a distant memory!
I think most people start feeling someone normal by 3 months, but maybe don't have a normal amount of energy until around month 6. Keep in mind that it takes a good year for the bone to completely set up hard. If you have nerve compression, you've probably heard that nerves are notorious for healing VERY slowly. Do not be surprised if you continue to have nerve pain for some time post surgery.
After surgery it is normal for the nerves to be even more irritated for awhile. Often the surgeon has to tug on the nerves to free them and the surgery itself is nothing more than a high-tech carpentry job involving drilling, hammering and a fair amount of brute force...so the area will be somewhat traumatized for awhile.
You will not be driving until you are off pain meds or until your surgeon clears you to drive. You will need to restrict any activity that involves bending or twisting at the waist, pushing, pulling, reaching overhead or to the side, and you will have a lifting restriction...like no more than a gallon of milk at the beginning. This will gradually be increased as you heal...but you may end up with a permanent restriction so you do not do further damage to the adjoining discs. I am not supposed to lift more than 30 pounds...so I had to learn a new skill -- saying "YES" when asked if I need help carrying the large bag of bird seed or dog food! I have had to learn to be a tad less independent in order to protect my back.
Ok-- this is becoming a book. Hope I've answered some of your concerns. Feel free to ask anything else you are wondering about. You are going to a great facility for your surgery and I imagine your surgeon is top-notch. You have youth on your side so hopefully surgery itself will be uneventful and you will heal relatively quickly. I wish you all the best.