title: A resorbable porous ceramic composite bone graft substitute in a rabbit metaphyseal defect model.
abstract: The success of converted corals as a bone graft substitute relies on a complex sequence of events of vascular ingrowth, differentiation of osteoprogenitor cells, bone remodeling and graft resorption occurring together with host bone ingrowth into and onto the porous coralline microstructure or voids left behind during resorption. This study examined the resorption rates and bone infiltration into a family of resorbable porous ceramic placed bilaterally in critical sized defects in the tibial metaphyseal-diaphyseal of rabbits. The ceramics are made resorbable by partially converting the calcium carbonate of corals to form a hydroxyapatite (HA) layer on all surfaces. Attempts have been made to control the resorption rate of the implant by varying the HA thickness. New bone was observed at the periosteal and endosteal cortices, which flowed into the centre of the defect supporting the osteoconductive nature of partially converted corals. The combination of an HA layer and calcium carbonate core provides a composite bone graft substitute for new tissue integration. The HA-calcium carbonate composite demonstrated an initial resorption of the inner calcium carbonate phase but the overall implant resorption and bone ingrowth behaviour did not differ with HA thickness.
authors.affiliation: Orthopaedic Research Laboratories, Orthopaedic Department, University of New South Wales, Prince of Wales Hospital, Sydney, Australia. w.walsh@unsw.edu.au
authors.forename: W R
authors.initials: WR
authors.lastname: Walsh
authors.forename: P J
authors.initials: PJ
authors.lastname: Chapman-Sheath
authors.forename: S
authors.initials: S
authors.lastname: Cain
authors.forename: J
authors.initials: J
authors.lastname: Debes
authors.forename: W J M
authors.initials: WJ
authors.lastname: Bruce
authors.forename: M J
authors.initials: MJ
authors.lastname: Svehla
authors.forename: R M
authors.initials: RM
authors.lastname: Gillies
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000648:ultrastructure; D001862:Bone Resorption / Q000188:drug therapy; D018786:Bone Substitutes / Q000494:pharmacology*; D002119:Calcium Carbonate / Q000493:pharmacokinetics; D002130:Calcium Phosphates / Q000378:metabolism; D002516:Ceramics; D018483:Diaphyses / Q000502:physiology / Q000601:surgery; D017886:Durapatite / Q000494:pharmacology*; D008855:Microscopy, Electron, Scanning; D023421:Models, Animal; D016348:Osseointegration / Q000187:drug effects*; D011817:Rabbits; D013977:Tibia / Q000502:physiology / Q000601:surgery*; D014102:Torsion Abnormality; D016474:Weight-Bearing
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; D017886:Durapatite; C020243:calcium phosphate; D002119:Calcium Carbonate; C485829:calcium phosphate, dibasic, anhydrous