How long ago was this? And which joint? It's possible that she sustained some nerve damage. Nerves don't repair themselves, but it's also possible that new nerves will try to forge new pathways in that area to try and repair function. With that much damage, I'm not sure.
If you prick her foot with a needle, does she feel it?
Vitamin E is very helpful for neurological repair in helping to rebuild what new pathways can be built. You can give human vitamin E supplementation to that effect. You can start with an human-intended oil vitamin capsule of combined vitamin E and selenium at 400-700 IU of vitamin E - just **make sure** that the Selenium is less than 50 micrograms. If you cannot get that, you can try oil capsules of just vitamin E.
You snip the end of the capsule and give the contents to the bird in the beak or in a quickly eaten small treat, like bread, a few crumbles, applesauce, etc.
That sort of repair takes a very long time. It might help her regain some function if that's possible.
You'll also want to watch that foot carefully for sores as it may drag the ground and break the skin. Monitor it over the course of her life and treat any broken skin immediately with cleansing and antibiotic ointment like neosporin, or better yet with a dry spray so it doesn't collect dirt and instead shields the wound from dirt.
