If there is any question about what your doctor is doing, get another opinion. If non fusion occured, going "IN" isn't going to do much. Exploring can be done with MRI. I wouldn't go that route unless another doc. concured with this dx, that surgery was necessary. Do you have a bone grown stimulator?
Did you have doner bone put in? Keep in touch. You can PM me anytime. Will give you my # if you need to talk. ginnie