A recent study from Sweden compared the results of patients with chronic low back pain (CLBP) who had a fusion to those who didn't. They found the cost was about twice as much for the fusion group. The fusion group also had twice as many patients that got better and went back to work.
There's no way to tell if you'll be in the back-to-work group or not. Returning part-time may be better than not at all for some patients. A good attitude goes a long way toward return to work. Good, overall health will also help. Follow your surgeon's advice about rehab and exercise after the operation.