Excluding surgical resolution of the leg angulation, these chicks tend to fair a poor prognosis as far as correcting angulation. Bracing tends to be unsuccessful, and could very likely worsen the problem. If you have a veterinarian in your area experienced with birds, it may be worthwhile speaking to them regarding surgical resolution. If not an option, you could attempt to see how the chick gets along, offer some supportive care, but if the improvement is not seen you may consider euthanasia. Slipped tendon often occurs when there is a mineral or vitamin deficiency.
https://www.metzerfarms.com/Veterinarians.cfm?CustID=27987794