Oh here this looks like a good site... the whole site seems good but for your situation.....
COPIED FROM WEBSITE
http://sites.google.com/a/larsencreek.com/chicken-orthopedics/leg-braces
"Fix Slipped Achilles Tendon in Hock Joint
Use to treat Slipped Achilles Tendon (tendon that runs down through the groove on the back of a chick's hock has slipped out of place off to the side). If a leg has this problem, the joint will look swollen and the back of the hock will look flat (Compare to other leg to double-check). The chick can't straighten its leg if this is what's wrong with it.
Gently pull the upper part of chick's leg a bit behind normal position and then carefully straighten the leg as though chick were stretching its leg back. The tendon should pop back into place pretty easily and cause little if any pain.
◦Some sources recommend pushing the tendon back in place just by pressing with your finger. However, stretching the leg back is a much less painful method.
Swelling on hock:
◦If infection is part of what is causing joint to swell, you will find pus. Recovery would be very difficult and the chick should probably be put down.
◦If it is just caused by displacement, swelling will go down in 2-4 days.
Put the chick in a Chick Chair and/or put its leg in a cast (such as one made from a drinking straw) for a few days (~5) while re-alignment stabilizes.
◦It is important that the legs not be able to touch the ground at all. The chick needs to hang with them bent and be discouraged from using its legs until the tendon has stretched and adjusted back to the right place and shape.
Note: It may take a few days for the groove to be fully developed on a young chick and you may have to fix the tendon more than once.
If there is pus in the joint,
[More info needed.]"