That happened to me three years ago. I was on my way downstairs to the laundry room, and the bleach fell out of my little cart and I didn't see it, and tripped over it. I went down so hard on my knees I thought I broke my kneecaps. My neighbors came out and put a chair in front of me so I could get up using the chair...but the pain was so intense I couldn't move for almost 15 minutes.