I Fell Earlier Tonight In My Garage On My Right

I fell earlier tonight in my garage on my right knee. I was unable to catch myself because I had my hands full so all of my weight landed on my right knee on the concrete. It is swollen, hot, and I can't bend it or straighten it. It hurts from the top of my knee to about half way down my calf. Hard to walk on it. Is this something I need to go to the er for? I am a 40 year old female.