My first thoughts looking at your chick would be mushy chick disease (omphilitis) as your chicks leg is very deformed in its leg I am presuming it can't stand? If it can't stand the open navel from hatch will have been exposed to the brooder floor and it's so easy to get infection in there.
Unless you can keep that area of the chick exceptionly clean and the brooder too the infection could kill the chick. Mushy chick can be deadly even for chicks that can stand. For me personally I would cull this chick if it were mine, not being able to stand is going to make the job of keeping things clean really hard. I am quite sure this is not want you want to hear but for sake of the chick I would cull.