What’s wrong with my roosters leg 😢

For context, he started limping about a year ago and slowly, I noticed his leg got swollen. He would limp a bit, but it was manageable. Eventually, it started swelling up, even thicker to the point you see now and he is at the point he doesn’t even use it at all. I thought maybe it was broken and had kept him isolated in a place in the coop where he could not jump up on anything for a month or so, but that doesn’t seem to help. I’ve tried reaching out to many different organizations near me and nobody can help me.