- The Chiarian
Depending on how bad the injury was to begin with. Sprains can take a few days to several weeks to heal. Is he still separated from the other one so that he doesn't run around too much and cause re-injury or delay in healing? He probably just needs some more time to heal. If it's swollen you may have to do another soak as explained in the other thread you created for duck leg (see link below).
Did you follow the instructions I gave you on your other thread?
Did you see the post from @CMV from another of your threads?
If they are continually fighting for dominance then you may have to separate them permanently or exchange one for a female.
On a side note for your information to help you get better assistance in the BYC forum. You had started 3 threads on the same topic. If you start a thread on a specific topic, continue to use that thread instead of making new ones. It keeps all the responses organized so everyone can see what advice you have been getting and better assist you.