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 How to keep joints lubricated Baptist Health Jacksonville, FL Lubricating Injections Can Soothe Knee Osteoarthritis Natural Joint Lubrication: How to Keep Your Joints Healthy Liv Hospital 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