I wonder if you have 18 ducks!
I'm not sure what can be done for a year-old injury, but here are some links you might interested in.
The first links are ideas to make a DIY duck wheelchair.
https://www.newscentermaine.com/article ... e5b4ac8601
This is for chickens but it shows ducks, too.
This is a commercial duck wheelchair.
This is a facebook group for Ducks With Disabilities started by one of our members, Sebastian's Mom.
https://www.facebook.com/people/Ducks-w ... 801984018/
This is a website about a duck with a different kind of disability, but it's a lovely website.
Hope something in one of these links will give you some ideas.