First, your employer tried to hide a legit w/c claim. Illegal.

Second, they fired you in retaliation for filing a claim. Also illegal.

Third, if your attorney has not discussed these two points with you and acted on them, I would shop a better attorney.

Fourth, your underlying degenerative changes should not bar getting treatment for the aggravation caused by the injury at work. And if the injury to the knee caused you to rely on the other leg more, that can be considered related. Again, a good attorney would comment on this too.

Looks like you have some work to do . . . hoping you are successful at the appeal.