A substance called hyaluronan, which is part of your normal joint fluid, helps to lubricate and cushion the joints and keep them working properly. Injections of hyaluronic acid into joints may help relieve pain in some people with mild to moderate knee OA. The most common side effect is pain where the needle went in. Examples of hyaluronic acid injections include Euflexxa, Hyalgan, Orthovisc, Supartz, and Synvisc.