Workers compensation deposition?

I have a workers comp claim that has been open for years. It has been accepted as 100 percent related to work. I am not represented for an attorney. I had to go in for a deposition today. I have seen a Qualified Medical Evaluator and is coming close to making a decision on my claim regarding the percentage I am disabled in any monetary compensation. Does anyone know why the insurance company would have me to do a deposition? Could this be because they are trying to reverse the decision that my claim is work related or could they be doing this to help them determine what and how much I should be compensated for?