title: Hydroxyapatite granule/carrier composites promote new bone formation in cortical defects.
abstract: BACKGROUND
  A great deal of interest has been focused on finding substitutes for autogenous bone grafts. Among the most interesting materials are different calcium phosphate compositions (e.g., hydroxyapatite [HA]), due to their biocompatible properties in hard and soft tissue.
  
  
  OBJECTIVE
  The bone response to porous ceramic HA granules in combination with two lipid and one polysaccharide carrier was evaluated in an experimental bone defect model in rabbits.
  
  
  METHODS
  Circular defects (Ø 4 mm) were made in both tibias of 32 rabbits. The 64 defects were divided into four groups. Group A was augmented with a composite of HA granules and a phospholipid-diacetyl-glycerol carrier, group B with HA granules and a phospholipid carrier, group C received HA granules and a sodium hyaluronan carrier, and group D served as control. The animals were killed after 6 weeks and ground sections were evaluated using light microscopic morphometry. X-ray microfluorescence (XRF) was applied in order to evaluate the suitability of this method to examine bone-biomaterial interfaces. Calcium distribution was studied using x-ray fluorescence line scans at selected interface regions of two sections in group B.
  
  
  RESULTS
  The HA/phospholipid composites were easier to shape and handle than the HA/hyaluronan composite. Group A had 36% newly formed bone area within the defect. Groups B and C showed significantly more newly formed bone within the defect (47% and 49%, respectively) compared to the control group (31%). The XRF analysis revealed that the amount of calcium in the newly formed bone was similar to that observed for the HA granules and slightly lower when compared to the mature, lamellar bone.
  
  
  CONCLUSIONS
  Synchrotron radiation may be a new, suitable technique to study the interface between bone and biomaterials with regard to mineral content. The results suggest that HA granule/lipid and HA granule/hyaluronan composites have interesting properties as bone-substitute materials.
authors.affiliation: Institute of Anatomy and Cell Biology, Göteborg University, Box 420, SE-405 30 Göteborg, Sweden.
authors.forename: E L
authors.initials: EL
authors.lastname: Liljensten
authors.forename: A G
authors.initials: AG
authors.lastname: Attaelmanan
authors.forename: C
authors.initials: C
authors.lastname: Larsson
authors.forename: H
authors.initials: H
authors.lastname: Ljusberg-Wahren
authors.forename: N
authors.initials: N
authors.lastname: Danielsen
authors.forename: J M
authors.initials: JM
authors.lastname: Hirsch
authors.forename: P
authors.initials: P
authors.lastname: Thomsen
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use; D001847:Bone Diseases / Q000473:pathology / Q000628:therapy*; D018786:Bone Substitutes / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use*; D002118:Calcium / Q000032:analysis; D002516:Ceramics / Q000627:therapeutic use; D003238:Connective Tissue / Q000473:pathology; D003931:Diacetyl; D004337:Drug Carriers; D017886:Durapatite / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use*; D004577:Electron Probe Microanalysis; D005260:Female; D005990:Glycerol; D006820:Hyaluronic Acid; D008297:Male; D010012:Osteogenesis / Q000502:physiology*; D010713:Phosphatidylcholines; D010743:Phospholipids; D011817:Rabbits; D013052:Spectrometry, X-Ray Emission; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013977:Tibia / Q000473:pathology
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D004337:Drug Carriers; D010713:Phosphatidylcholines; D010743:Phospholipids; D006820:Hyaluronic Acid; D017886:Durapatite; C017251:1,2-oleoylphosphatidylcholine; D003931:Diacetyl; D005990:Glycerol; D002118:Calcium