Glucosamine is a precursor of Hyaluronic Acid. Hyaluronic Acid in turn makes the synovial fluid. Glucosamine must combine with a glucuronic acid molecule to make Hyaluronic Acid. Often times the body is not able to join these two molecules together and the production of the much needed Hyaluronic Acid is never achieved. By administering Hyaluronic Acid, you take away the risk of this integral process not happening and may see results with Hyaluronic Acid that you did not see with glucosamine or chondroitin.