Knee osteoarthritis is a chronic degenerative joint disease characterized by destruction of articular cartilage with resultant para-articular bone changes. It is a major cause of disability in older persons and is managed by surgical and nonsurgical interventions. Pharmacotherapy includes acetaminophen, nonsteroidal anti-inflammatory agents, and intra-articular steroids. Another treatment option is viscosupplementation with intra-articular injection of hyaluronan (HA). The full mechanism of action of exogenous HA is uncertain, but studies indicate that it may promote endogenous HA production, reduce inflammation, prevent degeneration of cartilage and promote cartilage regeneration. Clinically, HA may improve symptoms of osteoarthritis and delay time to total knee replacement surgery. However, clinical studies are heterogenous and of varying quality, and thus there is a need for more robust studies to determine the place of viscosupplementation in the management of knee osteoarthritis.