Hyaluronic Gel Injections Twin Cities Pain Clinic Natural Release Muscle GEL Four Oaks Farm Products 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 A gel injection for the knee is often used when the joint loses some of its natural lubrication, which can happen with arthritis or cartilage wear., The gel acts as a lubricant and shock absorber