title: A preliminary report of percutaneous craniofacial osteoplasty in a rat calvarium.
abstract: OBJECTIVE
  To evaluate the potential for injectable, permanent bone augmentation by assessing the biocompatability and bioactivity of subperiosteal hydroxylapatite (Radiesse) deposition in a rat model.
  
  
  METHODS
  Randomized controlled animal model.
  
  
  METHODS
  Fourteen adult Sprague Dawley rats were injected in the parietal skull with 0.2 ml of hydroxylapatite (10 animals) or 0.2 ml of a carrier gel control (4 animals), using a subperiosteal injection technique on the right and a subcutaneous injection technique on the left. At 1, 3, and 6 months, three rats (1 negative control, 2 variables) were sacrificed and the calvaria were harvested. At 12 months, the remaining five rats were sacrificed. After each harvest, the specimens were processed and then examined under both light and polarized microscopy for new bone growth at the injection sites.
  
  
  RESULTS
  The inflammatory response was limited with both hydroxylapatite and carrier injections. Injectables were still present 12 months after the injection. New bone formation was only observed when the injection was located deep to a disrupted periosteum The odds of new bone formation was 48.949 times higher (95% confidence intervals CI [2.637, 3759.961]; P=0.002) with subperiosteal hydroxylapatite injections compared to all other combinations of injection plane and injectable.
  
  
  CONCLUSIONS
  This preliminary report of subperiosteal hydroxylapatite (Radiesse) injection in a rat model has verified the biocompatibility of injectable hydroxylapatite at the bony interface and suggests the potential for new bone formation.
  
  
  METHODS
  N/A.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, U.S.A.
authors.forename: William J
authors.initials: WJ
authors.lastname: Parkes
authors.forename: Jewel
authors.initials: J
authors.lastname: Greywoode
authors.forename: Brian J
authors.initials: BJ
authors.lastname: O'Hara
authors.forename: Ryan N
authors.initials: RN
authors.lastname: Heffelfinger
authors.forename: Howard
authors.initials: H
authors.lastname: Krein
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage; D060826:Cementoplasty / Q000379:methods*; D004195:Disease Models, Animal; D017886:Durapatite / Q000008:administration & dosage*; D007267:Injections; D010294:Parietal Bone / Q000601:surgery*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012887:Skull Fractures / Q000601:surgery*
chemical_list: D001672:Biocompatible Materials; D017886:Durapatite
keywords: Osteoplasty; hydroxylapatite