Hyaluronan
"I got three injections, a week apart.  The first two didn't hurt at all, but I got the third one from a different doctor and it hurt.  

After the first injection, my knee felt swollen on the inside and stiff, it got worse with each new injection.

I used to have pain pretty much only when I went on the stairs or twisted the wrong way.  Now it feels swollen in the joint and on my leg from a few inches above the knee to a few inches below the knee.  Like I am wearing a super tight bandage.  The pain has increased to the point it is really painful to go up or down the stairs and even at night lying in bed, it's hard to find a comfortable position because it feels like someone is drilling into my knee."