The chicks joint might be infected as well as not aligned right. I heard someone say to try fish antibiotics if you can't get some from a vet. I took a roo with an inflamed joint from injury to a vet and the vet put him down. In retrospect I would have liked to have tried antibiotics. As for chick orthopedics chicks respond very well if done early. Essentially you try to align every thing as it should be using vet tape, rubber bands, I like electrical tape and pipe stems as that kind of tape holds well and cuts loose easy, especially if you cut along the pipe stem. Keep in mind you don't want to rehurt in the process of removing whatever you put on. Set up first cutting strips of tape and materials before you handle the chick. If necessary you can wrap the chick and a paper towel and tape him to the table to work. If his legs are splayed a rubber band pinched at the top with tape can pull his legs together but also allow some flexibility. Vet tape is also very good, I like to line that with cotton. You might consider disinfecting what looks like an open wound in the picture. At any rate study the hurt chick against the healthy chicks and try to mimic their leg placement The earlier you fix it the better chance of total recovery. Usually 24 to 48 hours is all the chick will need. Curled toes for example will fix overnight on a newborn chick, an older chick things get harder and take longer. Look around the house and be creative if necessary. Growing up my mom used to set broken wings and legs of wild birds with toothpicks. I've used a narrow mug to hold a weak chick in the right position with wads of paper. They are really pliable day one. Good luck and keep us posted.