Any compensation you might be entitled to would be limited to coverage of your medical bills, and only then if a link between your job and the surgery could be proven.
You are free to try to submit a claim through your workers comp carrier and see what they say. It might be wise to consult with a workers comp attorney first, since you've already returned to work. But if your friend, or you, are thinking that you might be entitled to a large payout for damages, he (and you) are mistaken. A settlement when a case is closed, possibly (assuming you are able to make a case for workers comp at all). But you have not won the lawsuit lottery.
Now, as to your restrictions. Have you gone to HR and requested an accomodation under the ADA?
Two things I am tired of typing: 1.) A wrongful termination does not mean that you were fired for something you didn't do; it means that you were fired for a reason prohibited by law. 2.) The above answer, whatever it is, assumes that no legally binding contract or CBA expressly says otherwise. If it does, the terms of the contract apply.