title: Efficacy of a small cell-binding peptide coated hydroxyapatite substitute on bone formation and implant fixation in sheep.
abstract: Cylindrical critical size defects were created at the distal femoral condyles bilaterally of eight female adult sheep. Titanium implants with 2-mm concentric gaps were inserted and the gaps were filled with one of the four materials: allograft; a synthetic 15-amino acid cell-binding peptide coated hydroxyapatite (ABM/P-15); hydroxyapatite + βtricalciumphosphate+ Poly-Lactic-Acid (HA/βTCP-PDLLA); or ABM/P-15+HA/βTCP-PDLLA. After nine weeks, bone-implant blocks were harvested and sectioned for micro-CT scanning, push-out test, and histomorphometry. Significant bone formation and implant fixation could be observed in all four groups. Interestingly, the microarchitecture of the ABM/P-15 group was significantly different from the control group. Tissue volume fraction and thickness were significantly greater in the ABM/P-15 group than in the allograft group. Bone formation and bone ingrowth to porous titanium implant were not significantly different among the four groups. The ABM/P-15 group had similar shear mechanical properties on implant fixation as the allograft group. Adding HA/βTCP-PDLLA to ABM/P-15 did not significantly change these parameters. This study revealed that ABM/P-15 had significantly bone formation in concentric gap, and its enhancements on bone formation and implant fixation were at least as good as allograft. It is suggested that ABM/P-15 might be a good alternative biomaterial for bone implant fixation in this well-validated critical-size defect gap model in sheep. Nevertheless, future clinical researches should focus on prospective, randomized, controlled trials in order to fully elucidate whether ABM/P-15 could be a feasible candidate for bone substitute material in orthopedic practices.
authors.affiliation: Orthopaedic Research Laboratory, Department of Orthopaedic Surgery & Traumatology, Odense University Hospital, Institute of Clinical Research, University of Southern Denmark, 5000 Odense C, Denmark.
authors.forename: Ming
authors.initials: M
authors.lastname: Ding
authors.forename: Christina M
authors.initials: CM
authors.lastname: Andreasen
authors.forename: Mads L
authors.initials: ML
authors.lastname: Dencker
authors.forename: Anders E
authors.initials: AE
authors.lastname: Jensen
authors.forename: Naseem
authors.initials: N
authors.lastname: Theilgaard
authors.forename: Søren
authors.initials: S
authors.lastname: Overgaard
mesh_terms: D000818:Animals; D002417:Cattle; D020099:Coated Materials, Biocompatible / Q000494:pharmacology*; D017886:Durapatite / Q000494:pharmacology*; D005260:Female; D021621:Imaging, Three-Dimensional; D008422:Materials Testing; D010012:Osteogenesis / Q000187:drug effects*; D010455:Peptides / Q000378:metabolism*; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012756:Sheep; D055114:X-Ray Microtomography
chemical_list: D020099:Coated Materials, Biocompatible; D010455:Peptides; D017886:Durapatite
keywords: ABM/P-15; bone formation; histomorphometry; implant fixation; microarchitecture