Denied because they say my injury is from a pre-existing condition

Well, it finally happened. I got the denial letter in the mail yesterday and I've been stewing on it ever since. I hurt my lower back about four months ago while moving equipment at work, and the insurance company is now claiming that my MRI shows degeneration that existed before the accident, so they're denying the whole claim. The thing is, yeah, I'm in my forties and I've had some stiffness over the years, but I was working full duty with no restrictions before that day I felt something pop while lifting. Now my own doctor is saying the acute injury definitely happened at work, but the insurance doctor is pointing at the MRI and saying it's all pre-existing. I feel like they're twisting the truth to get out of paying for something that clearly happened on the job. I've been trying to figure out what my next move is because I know I have a limited time to challenge this, and I'm pretty sure I need someone who handles these appeals. I found a New Paltz workers comp appeal attorney online that seems to deal with exactly this kind of situation where the insurance company tries to blame everything on prior issues. Has anyone here successfully appealed a denial based on the pre-existing condition argument? I'm trying to get a sense of what I'm up against before I commit to anything, because this whole process has already been exhausting enough without having to start over.