If you have a torn meniscus, which is the cartilage in your knee, do you need to get surgery to fix it?

Not always: Pain from meniscal tears often settle down with therapy. Surgery only needed for continues pain or locking of the knee.

Usually: If it is painful yes. If it blocks your motion yes. If you can't bend or straighten all the way yes. If you are limiting your activity due to the pain or fear of pain, yes. If your knee is swelling a lot, yes. If it doesn't hurt or limit your activity then no.