title: The effects of microporosity on osteoinduction of calcium phosphate bone graft substitute biomaterials.
abstract: The effect of increasing strut porosity on the osteoinductive ability of silicate substituted calcium phosphate (SiCaP) biomaterials was investigated in an ectopic ovine model. Implants with strut porosities of 22.5%, 32.0% and 46.0% were inserted into the parapsinalis muscle. At 8, 12 and 24 weeks histological sections were prepared. Sections were examined using backscattered scanning electron microscopy and un-decalcified histology. Bone area, implant area and bone-implant contact were quantified. At 8 weeks there was no significant difference between the groups in terms of bone area and implant area. However at 12 weeks, the amount of bone formation observed was significantly greater in SiCaP-46 (6.17 ± 1.51%) when compared with SiCaP-22.5 (1.33 ± 0.84%) p=0.035. Results also showed significantly increased amounts of bone-implant contact to the SiCaP-46 scaffold (3.30 ± 1.17%) compared with SiCaP-22.5 (0.67 ± 0.52%, p=0.043) at 8 weeks and 12 weeks; (SiCaP-46 (21.82 ± 5.59%) vs SiCaP-22.5 (3.06 ± 1.89%), p=0.012). At 24 weeks, bone formation and graft resorption had significantly increased in all groups so that the level of bone formation in the SiCaP-46 group had increased 75-fold to 30.05 ± 8.38%. Bone formation was observed in pores <10 μm. Results suggest that bone graft substitute materials with greater strut porosity are more osteoinductive.
authors.affiliation: John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculoskeletal Science, Division of Surgery and Interventional Science, University College London, The Royal National Orthopaedic Hospital, Stanmore, Middlesex, UK. oliver.chan@doctors.org.uk
authors.forename: O
authors.initials: O
authors.lastname: Chan
authors.forename: M J
authors.initials: MJ
authors.lastname: Coathup
authors.forename: A
authors.initials: A
authors.lastname: Nesbitt
authors.forename: C-Y
authors.initials: CY
authors.lastname: Ho
authors.forename: K A
authors.initials: KA
authors.lastname: Hing
authors.forename: T
authors.initials: T
authors.lastname: Buckland
authors.forename: C
authors.initials: C
authors.lastname: Campion
authors.forename: G W
authors.initials: GW
authors.lastname: Blunn
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology*; D018786:Bone Substitutes / Q000494:pharmacology*; D016025:Bone Transplantation; D002130:Calcium Phosphates / Q000494:pharmacology*; D005260:Female; D020007:Implants, Experimental; D008855:Microscopy, Electron, Scanning; D016348:Osseointegration / Q000187:drug effects*; D010012:Osteogenesis / Q000187:drug effects; D016062:Porosity / Q000187:drug effects; D019919:Prosthesis Implantation; D012756:Sheep; D054457:Tissue Scaffolds / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D002130:Calcium Phosphates; C020243:calcium phosphate