Here are some links to read about the various leg bone deformities that can cause one or both legs to twist or rotate:
https://www.thepoultrysite.com/articles/leg-health-in-large-broilers...
Can you get a picture of her standing from the front or back that clearly shows her leg conformation? She could possibly have a leg bone deformity that has worsened with age. Sometimes those can eventually end up with a ruptured hock tendon. Varus and valgus deformities are the ones that are...