I would add to what Amiga wrote...she gives you excellent advice for topical cleaning of the infection, that is, on the wound's surface. But that infection looks like it has gone into the duck's joint and could next become systemic, which would kill your duck (of a staph infection, probably).
Long story short, Lucky needs an antibiotic immediately. They sell an antibiotic that will kill staph called oxytetracycline hydrochloride at most pet food stores, in the bird section. They also may sell it at Tractor Supply stores. I need to check on the dosage, but I think that a duck would need 50 mg per kg (that is, 50 mg for every 2.2 lbs your duck weighs) of powder each day, for maybe 10 days. You would dissolve the powder in water and give it to Lucky in a few separate doses per day.
If you can't find the oxytetracycline hydrochloride powder for birds, they may sell it in the fish section of aquarium stores. If you still can't find it, then the best antibiotic alternative that's available at a supplement store is called Silver Biotics, or Sovereign Silver. Either of these silver solutions will kill any bad bacteria that have gotten into Lucky's system. You would give your duck a tablespoon of silver solution dissolved in a couple tablespoons of distilled water, on an empty stomach, every 4-6 hours. Put that solution by her all night to drink from.