My wife is the poster-child for this surgery. Here's our story:
My wife was a police officer for 16 years. Back in 2003, she was taking a drunk lady to jail, and had to walk her up the steps at the courthouse. The drunk lady passed out, my wife went to catch her, and herniated 6 discs in her lumbar region.
After months of therapy and intense, debilitating pain, she had spinal fusion surgery. Keep in mind in most cases people do not qualify for disc replacement as it is only available for very specific types of conditions.
The spinal surgery limited her movement and appeared to cause some nerve damage. This lead to chronic pain, to which she was perscribed pain meds and steriods. Over long term use, pain meds lose their effectiveness, so you have to keep upping the dose and trying alternatives. At one point she was taking 800mg of oxycodone, percocet, and a couple drugs...pretty much making her sleep 16 hours a day. This and a combination of the steroids caused severe weight gain, which in turn caused swelling and even more pain. She was diagnosed with fibromyalgia (which is doctor speak for "we don't know what's wrong with you"), and she was given even more meds. She was up to 20+ pills a day.
This went on for a good 10 years or so, and we just figured she was going to end up dying from liver failure in her 50s. Then, two years ago, after a ton of research, we met up with a doctor that finally figured it out. He said the pain was initially from the spinal healing process, which can take years, but that subsided, and now she's just dealing with pain from swelling issues and side effects from medications! He prescribed medications they give drug addicts to ween them off of pain meds, and weightloss surgery.
It took a year for the doctor to convince the insurance company that the weightloss surgery wasn't for cosmetic reasons...it was needed to get rid of her chronic pain. If she can't move, she can't exercise, and she needs to exercise to drop body mass and build up muscle.
She had the surgery last year, dropped over 100 lbs, and since then has stopped all medications! She looks and feels great (hell...she looks HAWT!), and this year started working as a teaching assistant full time helping special needs kids. I got my wife back
So, my advice to take out of this experience: do not let doctors overprescribe medications, the surgery will not remove all pain immediately, and force yourself to keep moving to speed the healing process. Good luck!