A clear gel filled in a syringe, obtained by dissolving sodium hyaluronate or hyaluronic acid (hereinafter referred to as “HA”) in phosphate-buffered saline. It is intended for a single intra-articular injection. The product is a unique type of linear macromolecular mucopolysaccharide, which is formed by repeating disaccharide units of glucuronic acid and N-acetylglucosamine. The chemical formula is (C 14 H 21 NO 11 ) n .