title: Osteoconduction in keratin-hydroxyapatite composite bone-graft substitutes.
abstract: Reconstituted keratin-hydroxyapatite (K-HA) composites have shown potential as nonload-bearing bone graft substitute material. This in vivo study investigated the bone regeneration response of keratin plus 40% HA composite materials in comparison to collagen counterparts and an unfilled defect site. The implantation site was a noncritical size defect created in the long bones (tibia) of sheep, with observations made at 1, 2, 4, 6, 8, and 12 weeks postimplantation. Porous K-HA materials displayed an excellent biocompatibility similar to collagen counterparts; however, the rate of bone regeneration at K-HA implantation sites was markedly slower than that of the collagen or unfilled defect sites. While collagen materials were undetectable by 4 weeks implantation, K-HA composite remnants were present at 12 weeks. However, there is evidence that K-HA implants participated in the natural remodelling process of bone, with bone regeneration occurring via a creeping substitution mechanism. Observations imply that the rate of bone ingrowth into the K-HA defect site was matched with the rate of K-HA resorption. These results suggest that K-HA materials may offer significant benefits as nonload-bearing bone graft substitutes where it is desirable that the degradation of the scaffolding material be well matched with the rate of bone regeneration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2034-2044, 2017.
authors.affiliation: Department of Anatomy, University of Otago, Dunedin, New Zealand.
authors.forename: George Jayantha
authors.initials: GJ
authors.lastname: Dias
authors.affiliation: Department of Anatomy, University of Otago, Dunedin, New Zealand.
authors.forename: Patricia
authors.initials: P
authors.lastname: Mahoney
authors.affiliation: Department of Pathology, University of Otago, Dunedin, New Zealand.
authors.forename: Noelyn Anne
authors.initials: NA
authors.lastname: Hung
authors.affiliation: Department of Anatomy, University of Otago, Dunedin, New Zealand.
authors.forename: Lavanya Ajay
authors.initials: LA
authors.lastname: Sharma
authors.affiliation: Center for Clinical Reserach, University of Queensland, Australia.
authors.forename: Priyakshi
authors.initials: P
authors.lastname: Kalita
authors.affiliation: Keraplast Technologies Ltd, San Antonio, Texas.
authors.forename: Robert Allen
authors.initials: RA
authors.lastname: Smith
authors.affiliation: Keraplast Technologies Ltd, San Antonio, Texas.
authors.forename: Robert James
authors.initials: RJ
authors.lastname: Kelly
authors.affiliation: Department of applied sciences, University of Otago, Dunedin, New Zealand.
authors.forename: Azam
authors.initials: A
authors.lastname: Ali
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000187:drug effects*; D018786:Bone Substitutes / Q000737:chemistry / Q000494:pharmacology*; D017886:Durapatite / Q000737:chemistry / Q000494:pharmacology*; D005260:Female; D007633:Keratins / Q000737:chemistry / Q000494:pharmacology*; D012756:Sheep; D013977:Tibia / Q000293:injuries / Q000378:metabolism / Q000473:pathology
chemical_list: D018786:Bone Substitutes; D007633:Keratins; D017886:Durapatite
keywords: bone graft substitute; creeping substitution; keratin; keratin-hydroxyapatite; osteoconduction