I fell and injured my knee 2 days ago. It has been x-rayed and nothing broken, but when I try to put weight on it, from ankle to knee goes inward and the top goes outward. It feels like I have a rubberband holding my knee together. I did hear a pop when I fell. Is it my acl or could it be just tendons and ligaments? I have an appointment with an orthopedic in 2 days. I am just wondering if this could require surgery