Last night, I was walking and my left knee twisted and popped. Afterwards, there was an extreme amount of pain and it hurt to walk. Today, I haven t noticed any swelling but it still hurt for most the day. I took some pain relievers and the pain has gone down, but I am unsure of whether the pain will return. Is it possible that I tore a ligament or could it just be a muscle strain? I have hurt my other knee before, and it was a torn ligament.