I tend to let mine be with the flock. I have a slight bank they go up and down ranging around their large area. I put several pans of feed and water, so they can go far or eat close to the coop or in the coop and run. If one is truly struggling to walk , I will place them in a dog pen with food and water, or in a larger pen with a friend if needed. The crate can be mived to where the flock is hanging.
Some injuries need rested though. I think they will tend to limit their own activity if they are hurting, unless they are a wild one or a hormone-driven rooster. I usually recommend some vitamin B complex 1/2 tablet crushed over feed daily, just to help out in case they are lacking. High roosts can be bad on legs and hips, so I try to prevent jumping down especially. Sometimes they can spend the nights in a pen on the ground and get let out in morning to handpg with the flock.
If you need to put her down or she would die, here is a contact number for all of the state vets where you can ask questions about prices, Mareks testing, and the cheapest way to send the body which has to be refrigerated, not frozen. Also, find out if you can send it independently or if you have to deal with a local vet, which costs more. Here is the link:
http://www.metzerfarms.com/PoultryLabs.cfm