Osteoarthritis (OA), which is caused by the breakdown or wearing away of cartilage in joints, is the most common joint disorder in the United States and worldwide. Although ankle OA is much less common than knee and hip OA, pain, swelling, and stiffness due to OA in one or both ankles can adversely affect patient mobility and quality of life. Healthy joints are protected by a viscous, elastic synovial fluid that helps lubricate the joints during slow movements and helps absorb shocks during rapid movements. One of the primary components of healthy synovial fluid is hyaluronan, which is made up of long chains of sugar molecules. In patients who have OA, the chain length and amount of hyaluronan in synovial fluid is decreased. This alters the properties of the synovial fluid and can interfere with normal joint function. To attempt to improve joint function, a treatment known as
viscosupplementation therapy has been developed and it involves injection of viscoelastic fluid into the affected joints.