What possible problems would I face if I don't go to physical therapy?

In all honesty, we can't really say for sure. There is evidence that people have less pain when they are involved in a PT program after surgery in the short term, but the long term results are less definitive. People tend to be the same two years later whether they did "light" or "intense" therapy after back surgery. The study to which I'm referring is one that involves microdiscectomy...you've had a fusion...we know even less about that...take into account that your fusion was because of an accident and not due to degenerative changes, we know even less...the research on it is either scant or does not exist.

From a professional standpoint, I really think there is little that needs to be done on a 2-3x a week basis...most of the exercises that would be appropriate for you should be done at home. That being said, I'd much prefer to see someone with a fusion on a 1x a week or every other weeks basis simply for home exercise program updates...but most surgeons and patients really want that 2-3 x a week contact. Which is pointless to have me watch you do the same exercises in the gym that you should be doing at home.

My advice: see someone who offers a decent cash based rate...small private clinics will typically give you a better deal than an "athletico" or "health south" or hospital based clinic. Make arrangements to see them on a 1 x a week or every other week basis to learn what you can be doing at home.