Sis, I'm so sorry your sister has to go through this pain. Big {{{hugs}}} to you both. My left knee had hardly any cartilage in it. I went through orthoscopic surgery first and that didn't work so I had the knee replaced. As others said, it's major surgery and physical therapy afterwards, but in my case mine was done 4 years ago and I can walk normally, I can work without pain, I can even bowl ( not that good at bowling!) and basically do what I have to do. It's a lot to go through. but worth it. They normally do one at a time.