title: Effect of increased strut porosity of calcium phosphate bone graft substitute biomaterials on osteoinduction.
abstract: The effect of increasing strut porosity on the osteoinductivity of porous calcium phosphate (CaP) and silicate-substituted calcium phosphate (SiCaP) bone substitute materials was investigated in an ovine ectopic model. One to two millimeter-sized granules or block implants with strut porosities of 10, 20, or 30% were inserted into the left and right paraspinalis muscle. At 12 weeks, histological sections were prepared through the center of each implant and bone contact, bone area and implant area quantified. Backscattered scanning electron microscopy (bSEM) was used to visualize bone within small pores in the struts of the scaffolds. Increased bone formation was measured in the SiCaP with 30% strut porosity (5.482% ± 1.546%) when compared with the nonsilicate CaP with the same morphology (1.160% ± 0.502%, p = 0.02), indicating that silicate substitution may increase osteoinduction. Greater bone formation was seen in scaffolds with increased strut porosity. No bone growth was found in any of the SiCaP scaffold with 10% porosity. There was no significant difference between block and granule specimens. Scanning electron microscopy and EDX in combination with histology demonstrated bone formation within pores <5 μm in size. The use of silicate-substituted CaP material with increased strut porosity may further augment repair and regeneration in bony sites.
authors.affiliation: Division of Surgery and Interventional Science, John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculoskeletal Science, University College London, Royal National Orthopaedic Hospital, Stanmore, United Kingdom. m.coathup@ucl.ac.uk
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Coathup
authors.forename: Karin A
authors.initials: KA
authors.lastname: Hing
authors.forename: Sorousheh
authors.initials: S
authors.lastname: Samizadeh
authors.forename: Oliver
authors.initials: O
authors.lastname: Chan
authors.forename: Yvette S
authors.initials: YS
authors.lastname: Fang
authors.forename: Charlie
authors.initials: C
authors.lastname: Campion
authors.forename: Thomas
authors.initials: T
authors.lastname: Buckland
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Blunn
mesh_terms: D000818:Animals; D018786:Bone Substitutes / Q000737:chemistry / Q000378:metabolism*; D002130:Calcium Phosphates / Q000737:chemistry / Q000378:metabolism*; D010012:Osteogenesis; D016062:Porosity; D012756:Sheep; D017640:Silicates / Q000737:chemistry / Q000378:metabolism; D054457:Tissue Scaffolds / Q000737:chemistry
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; D017640:Silicates; C020243:calcium phosphate