title: Semipermanent volumization by an absorbable filler: onlay injection technique to the bone.
abstract: BACKGROUND
  Hyaluronic acid (HA) fillers have become the most popular tool for wrinkle treatment and volumization, although HA is generally absorbed within 6-12 months and requires repeated treatments to maintain the effects.
  
  
  METHODS
  HA was injected onto the bone for volumization with a small 30-gauge needle to examine the long-lasting effects. Of the 63 Japanese patients with 97 treated sites followed up more than 12 months, 51 had HA injections for cosmetic purposes and 12 were treated for reconstructive volumization of facial deformity such as localized scleroderma and postsurgical bony deformity. Treated sites included the forehead, temple, nasal root, mentum, tear trough, and infraorbital sulcus.
  
  
  RESULTS
  After long-term follow-up (12-93 months, mean = 21.6), persistent volumizing effects were observed in most patients. In fact, 86.6% of the treated sites showed >50% volume retention and 49.5% showed >75% retention. Magnetic resonance imaging analyses revealed that the injected space was well maintained, capsulated, and filled with heterogeneous content. Magnetic resonance imaging quantitative T2 maps indicated that much of the injected HA was replaced with other materials. Together with clinical inspection, these findings suggest that onlay injection of HA on the bone induced formation of capsule, fibrosis, and/or calcification/ossification, which contributed to persistent volumization.
  
  
  CONCLUSIONS
  Semipermanent volumizing effects can be achieved by HA injection if the target area has an underlying bony floor. Periosteal stem cells may be activated by HA injection and may contribute to persistent volumizing effects. This treatment may be a much less invasive alternative to fat or bone grafting.
authors.affiliation: Department of Plastic Surgery, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan; and the Department of Radiology, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan.
authors.forename: Takanobu
authors.initials: T
authors.lastname: Mashiko
authors.affiliation: Department of Plastic Surgery, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan; and the Department of Radiology, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan.
authors.forename: Harushi
authors.initials: H
authors.lastname: Mori
authors.affiliation: Department of Plastic Surgery, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan; and the Department of Radiology, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan.
authors.forename: Harunosuke
authors.initials: H
authors.lastname: Kato
authors.affiliation: Department of Plastic Surgery, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan; and the Department of Radiology, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Doi
authors.affiliation: Department of Plastic Surgery, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan; and the Department of Radiology, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Kuno
authors.affiliation: Department of Plastic Surgery, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan; and the Department of Radiology, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan.
authors.forename: Kahori
authors.initials: K
authors.lastname: Kinoshita
authors.affiliation: Department of Plastic Surgery, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan; and the Department of Radiology, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kunimatsu
authors.affiliation: Department of Plastic Surgery, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan; and the Department of Radiology, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan.
authors.forename: Kuni
authors.initials: K
authors.lastname: Ohtomo
authors.affiliation: Department of Plastic Surgery, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan; and the Department of Radiology, University of Tokyo School of Medicine, Bunkyo-Ku, Tokyo, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Yoshimura