Most likely you had your knee injected with a product called hyaluronic acid (HA). This thick liquid helps restore the knee's natural lubrication. There are many types of HA on the market.

The two major kinds are cross-linked and noncross-linked. Studies show the cross-linked HA can result in a minor adverse reaction. The increase in local pain and swelling doesn't last long. Researchers don't think it damages the knee either.

This type of reaction may be what happened in your case. There are other causes of the local symptoms you've described. Make sure your doctor knows about these changes. The doctor may be able to treat the problem early on and prevent more damage to the joint.