What's wrong with my duck's leg? Swollen with a growth

Does anyone know what's wrong with my duck? She's a year and a half old Golden 300 duck. She'd started limping a while back, and figured she'd get better, as two other ducks had limped for a day and then got better. But, she didn't get better, and we noticed that her leg looked swollen. I finally got a good look at her let (needed to get my husband to help catch her), and noticed a growth of some sort protruding from her leg. I tried to get a picture of it, but she's skiddish and my camera has horrid zoom. Here's the best picture I could get. I'll try to get a better one tomorrow.

Anyone have any ideas what's going on with her leg?

I have no idea what is wrong with yours, but we have a duck we named Gimpy that has had a broken leg for at least two years. She's doing fine, even if she limps a lot and doesn't explore as much as the rest of the duck collective. (I miss Evan's duck tales.)