Arthritis treatment. Conceptual computer artwork showing lubricating fluid treatment for an arthritic knee joint. The lubricating fluid (blue), a formula based on hyaluronic acid, washes and bathes the inflamed knee joint (orange- brown), filling the space and coating the joint. The result is pain relief and improved mobility due to the lubricating effects of the fluid. This type of treatment is known as viscosupplementation and was first approved for use in the USA in 1997. Hyaluronic acid is a naturally occurring substance found in the synovial (joint) fluid. It acts as a lubricant to enable bones to move smoothly over each other and as a shock absorber for joint loads.