Thank you!In addition to the aspirin, treat for shock. Warm sugar water, a fourth of a cup water with a teaspoon of sugar and a pinch of salt and baking soda. He will probably drink it on his own as it tastes sweet. You can add a tablespoon of flavored Jello if he won't. Chickens like the red flavors.
I would splint the leg to immobilize it. Wrap the joint with several layers of gauze to pad the leg well, then use popsickle sticks and Vetrap them to the joint. Or you can slice an empty toilet paper roll length-wise and fit it over the joint so it's snug, then Vetrap it securely.