I had knee surgery. I was a catcher my entire life and tore my meniscus in half. They had to insert a gel in place of it.
I will tell you this, it will never be the same. Knee surgery sucks. It will constantly ache and she will always know when the weather is changing

hahaha
Honestly though, I was never the same with lifting legs. I can still go very heavy, but it starts to hurt if I continue for a while. The next day is brutal after doing legs. The best advice I could give her is to go easy and slow and to wear a knee brace when lifting. It helps me a lot! Hopefully she recovers well.