How to fix a crippled / disjointed leg?
For anyone who may stumble upon this post with the same question - I discovered his leg has a slipped tendon, or a "slipped achilles tendon in hock joint." I looked up the anatomy of a chicken - it is his hock he is walking on (in my first post I called it his knee). From what I've read, it is treatable if treated within 24-48 hours. I tried to pull the leg back and rub it into place, but it only resulted in his hock bleeding.
Here is a link that I found to be helpful: https://sites.google.com/a/poultrypedia.com/poultrypedia/poultry-podiatry
You have to scroll down to where it says "Fix Slipped Achilles Tendon in Hock Joint."