What Causes Knee Pain Post Injury With History Of Knee Replacement?

I am a 37 year old female with an artificial right knee. I had the total knee replacement about 1 year ago and today I was pushed down sideways and i felt something make a horrible noise in my knee and now im scared that i have injured it :-( the pain was so severe that i buckled over and ended up and the floor in excruciating pain. I laid there for a little bit then took my time getting up because i wasnt sure i would even be able to walk. I am currently able to walk and put some weight on it but im in severe pain while doing so. I am wanting to know if you can injure a knee that has had a total knee replacement? if so what type of injuries can be caused by my accident? thank you in advance