For about ten years prior to my bilateral TKRs, I regulary had cortisone injections in both knees and at the end, switched to Synvisc.
The Synvisc injection itself is no worse than a cortisone injection. However, as soon as the needle is pulled out, the Synvisc stings like Hell. I don't want to scare you off, but, everyone I know who has Synvisc injections agrees with me.
However, that being said, the relief that Synvisc gave me from chronic knee pain was well worth the painful sting following the injections! I got them regularly every six months until my surgery.
The only problem for me was that the relief didn't last the entire six months. I was so overweight, the relief only lasted about one month. However, that one month felt like heaven on earth.