My knee hyperextended tonight in sparring.
We were only sparring to the body, no head punches, which leads to a very close, high-intensity battle. I was sparring with a tall, fellow brown belt in his mid to late teens. We were both clinching for knee kicks, if I recall; he stepped back, and I put my weight on my recovering left leg and hyperextended it. I went down right away. I got hurt even though I was wearing my brace, which primarily prevents the knee from going sideways.
My ACL is fine, but I pulled something behind and on the side of my knee. If I try to straighten out my knee, it hurts. I am walking very carefully and will probably work from home tomorrow. I've been icing my knee, I took a naproxen, and I had a couple sips of red wine to boot.
It was heart-warming how quickly classmates and my sensei came to my aid when I fell. Everybody was worried I had re-injured my knee. Nothing popped, but it sure is sore.
My wife and daughter got me ice and cleared off the couch. I can see they're worried.