Cyn,
If the chick is actually able to walk on its feet, then I would think there was hope as long as that tendon is in correct position.
Mine could do nothing but walk on the hock joint, and its other foot was bad as well. I had read about the sling, but not seen the chick chair, what a wonderful idea.
I fashioned a sling for my baby from the kitchen towels that wrap around the stove handles, I had some soft knitted ones that I just cut, then hung in the brooder from a hanger with her one other hatchmate, and he was really good about not picking on her after he got used to it.
She could also reach the wet mash I fixed up, as I was afraid of doing a water dish as well. You think if you had her in a sling her leg could heal up?
Pics of what I rigged for my baby, if her leg probs hadnt been SO extensive I would not have put her down. It was such a struggle for her tho, I gave her two weeks, and it just wasnt happening, I cried to watch her try to walk when I put her in the grass. I dont have the splint on her here, but she had bent toes, spraddle leg, AND the slipped tendon, was just too much for her. I know putting those splints on or taping that tendon has to hurt but necessary evil I guess.