I twiste my knee, it hurts on the inside it has swelling it hurts a lot so i am limping i can't straighten it i tried i heard a grinding noise any idea?

Ligament tear: You may have experienced a ligament tear or join injury. You should be seen by an orthopedist as soon as possible.

See the doctor: There are a couple of possibilities, including a torn cartilage, loose body or problems with the surface of the lining cartilage. Particularly if you can't fully straighten your knee, you should see an orthopedic surgeon sooner rather than later.