You'll need to immobilize the chick - dragging the leg around will definitely not help. Look up "chick chair" - there are lots of ways to do it- then have little water and food dish in easy reach. I used the cups from on top of the Nyquil bottle after a major washing - poked a little hole in the top and used a twisty-tie to secure it. A chick chair is basically a sling that lets the leg hang instead of getting banged around. It's important
Yes, I pretty much left the bone out- there wasn't much else I could do. I manipulated both sides and sought to cast the leg in the most natural possible position. He was bleeding heavily, so my first problem wasn't so much the break- it was stopping the bleeding. Given his size, it wasn't likely that I was going to accomplish anything else - it's been said with young animals that if you have a break and you put the two halves in the same room together, they'll grow together.
The wound was open for over a month because so much of the skin and surrounding tissue was damaged from him trying to free himself. I thought it was just about done … then had that nice infection come spewing out, but since then the skin has healed.
I had a couple things going for me- my guy continued to eat and drink through the whole thing, and while he was with his mom and siblings when the accident happened, he was big enough to be comfortable indoors without special heat etc. Going under momma hen isn't going to be good for that leg- baby can be in the same area with others but will need to be supported- kind of like confining a patient to bed.
And I still had some toe/lower leg movement. Now when I go to stretch the bad side, there's a little bit of flexion in the foot but not like the undamaged side. And the hock has some flexibility but not a normal range of motion as the bones had to heal whichever way they could with the support of the cast.
He can stand, walk, and run if he uses his wings- by no means 100%.