Gelsyn-3 Injection Hyaluronic Acid Prefilled Syringe Injection Treatments 16.8 mg /2 mL (Rx)Gelsyn 3 is a Sodium Hyaluronate Injection Syringe used to reduce knee pain due to osteoarthritis. This highly advanced product features non animal sourced sodium hyaluronate with a high molecular weight that can absorb more than 45 times it weight in water. When injected directly into the knee joint through Gelsyn 3 Injection, the gentler viscosity provides smoother application and helps knee joint movement for better access to the knee joint