It may be a slipped tendon. Google 'chick, slipped tendon' and you will find videos and links to help you determine if that's what it is and how to treat. Here is a link with some good info and instructions, scroll down to 'slipped achilles tendon in hock joint' : https://sites.google.com/a/poultrypedia.com/poultrypedia/poultry-podiatry
Hope this helps
Thank you for the link. I think i will need a vet to look at it, as it was an injury, however, not sure if what it is. Tractor Supply only said he was run over. I could not resist his strength to keep up with buddies.also felt that he,would never be purchased.