Logan Mankins played an entire season with a torn ACL. Hell, many non-athletes who tear their ACL don't even have the surgery and just lives the rest of their lives with a torn ACL.
Never torn my ACL or had anything worse to my knees than a PCL strain that didn't hurt although my knee bent backwards and lost stability. But I can tell you having a bad ankle sprain was really painful. Probably the worst sports injury I ever had in terms of pain and I broke and dislocated a couple of fingers back in my high school football days.