Cross-linked hyaluronic acid fillers

Three hyaluronic acid fillers have received U.S. Food and Drug Administration approval for "mid-to-deep dermal implantation for the correction of moderate to severe facial wrinkles and folds." As plastic surgeons incorporate these fillers into their practices, it is essential that they understand not only the uses and longevity of these three fillers but also all of the potential problems. To stabilize hyaluronic acid, the small natural molecules must be bound, or "cross-linked," to each other with repeating chemical bridges to form a much larger molecule. It is that linking that makes the hyaluronic acid resistant to mechanical and enzymatic degradation and thereby able to remain in the body for months after implantation. These chemical bridges, however, introduce additional chemicals to the natural hyaluronic acid that can potentially cause problems. Some of the reactions should be considered normal sequelae of implantation, but some may precipitate immunologic reactions and granulomas. Ongoing studies are essential for the identification and quantification of such complications. In addition, as with any procedure, technical problems may occur, such as lumpiness and discoloration. More alarming, injection of hyaluronic acid into an artery or vein can potentially result in embolization, with skin necrosis and even blindness or stroke. To give adequate informed consent, every physician should be aware not only of the uses and longevity of hyaluronic acid but also its potential complications. Copyright ©2006 by the American Society of Plastic Surgeons.