Her legs appear as though she has a leg bone deformity or possibly a twisted tibia. Slipped tendons do seem to cause the joint swelling of the hock, and can become scabbed. I would go ahead and add a vitamin containing riboflavin right away. Sorry that this may end up with a bad outcome, but she seems to be a fighter. I think trying to see if she can get around to get food and water.
Here is some info on leg bone deformities—varus and valgus deformity and twisted tibia in one or both legs:
https://www.researchgate.net/public..._of_the_Intertarsal_Joint_in_Broiler_Chickens
https://thepoultrysite.com/articles/leg-health-in-large-broilers
https://www.merckvetmanual.com/en-c...ctious-skeletal-disorders-in-poultry-broilers
Here is some info on leg bone deformities—varus and valgus deformity and twisted tibia in one or both legs:
https://www.researchgate.net/public..._of_the_Intertarsal_Joint_in_Broiler_Chickens
https://thepoultrysite.com/articles/leg-health-in-large-broilers
https://www.merckvetmanual.com/en-c...ctious-skeletal-disorders-in-poultry-broilers