Joints are like gears. They work best if they’re well lubricated. In a healthy joint, a thick substance called synovial fluid provides lubrication, allowing bones to glide against one another. Synovial fluid acts as a shock absorber, too. In people with osteoarthritis, a critical substance in synovial fluid known as hyaluronic acid breaks down. Loss of hyaluronic acid appears to contribute to joint pain and stiffness. Osteoarthritis of the knee is one of the leading causes of disability in the world. It develops slowly and the pain it causes worsens over time. Although there is no cure for osteoarthritis, there are many treatment options available to help people manage pain and stay active, including : Changes in activity level, Weight loss, Pain relievers : acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), Physical therapy, Corticosteroid injections Another treatment option is a procedure called viscosupplementation. In this procedure, a gel-like fluid called hyaluronic acid is injected into the knee joint. Hyaluronic acid is a naturally occurring substance found in the synovial fluid surrounding joints. It acts as a lubricant to enable bones to move smoothly over each other and as a shock absorber for joint loads. People with osteoarthritis have a lower-than-normal concentration of hyaluronic acid in their joints. The theory is that adding hyaluronic acid to the arthritic joint will facilitate movement and reduce pain.