Joint fluid fills the small space between the ends of bones and acts like a natural lubricant. The synovial membrane creates this thick, silky fluid using long molecules that hold water and give it a How Do Synovial Joints Work? Hyaluronic acid injections are designed to support joint lubrication and improve knee functionhelping to ease symptoms in some people with knee osteoarthritis. They work best as part of a bigger plan, Painful joints? They might need lubrication. Life Force Physiotherapy How to Increase Grease in Knees Naturally?