Leg deformities usually cannot be fixed. Some have had success treating a slipped tendon if you read all of the threads about it on BYC, but leg bone deformities tend to worsen as the chick grows, many times causing the hock tendon to rupture. About the only thing I could suggest is to treat with vitamins and minerals, and try and let the chick get along as normalcy as possible with it's handicap. If it gets in too much pain, or the quality of life goes down, then helping it out of it's misery would be the right thing to do.