title: Healing of segmental bone defects with granular porous hydroxyapatite augmented with recombinant human osteogenic protein-1 or autologous bone marrow.
abstract: Hydroxyapatite is a synthetic bone graft, which is used for the treatment of bone defects and nonunions. However, it is a rather inert material with no or little intrinsic osteoinductive activity. Recombinant human osteogenic protein-1 (rhOP-1) is a very potent biological agent, that enhances osteogenesis during bone repair. Bone marrow contains mesenchymal stem cells, which are capable of new bone formation. Biosynthetic bone grafts were created by the addition of rhOP-1 or bone marrow to granular porous hydroxyapatite. The performance of these grafts was tested in a sheep model and compared to the results of autograft, which is clinically the standard treatment of bone defects and nonunions. A 3 cm segmental bone defect was made in the tibia and fixed with an interlocking intramedullary nail. There were five treatment groups: no implant (n=6), autograft (n=8), hydroxyapatite alone (n=8), hydroxyapatite loaded with rhOP-1 (n=8), and hydroxyapatite loaded with autologous bone marrow (n=8). At 12 weeks, healing of the defect was evaluated with radiographs, a torsional test to failure, and histological examination of longitudinal sections through the defect. Torsional strength and stiffness of the healing tibiae were about two to three times higher for autograft and hydroxyapatite plus rhOP-1 or bone marrow compared to hydroxyapatite alone and empty defects. The mean values of both combination groups were comparable to those of autograft. There were more unions in defects with hydroxyapatite plus rhOP-1 than in defects with hydroxyapatite alone. Although the differences were not significant, histological examination revealed that there was more often bony bridging of the defect in both combination groups and the autograft group than in the group with hydroxyapatite alone. Healing of bone defects, treated with porous hydroxyapatite, can be enhanced by the addition of rhOP-1 or autologous bone marrow. The results of these composite biosynthetic grafts are equivalent to those of autograft.
authors.affiliation: Department of Surgery/Traumatology, VU University Medical Centre, de Boelelaan 1117, 1081 HV Amsterdam, The Netherlands. frankdenboer@hotmail.com
authors.forename: Frank C
authors.initials: FC
authors.lastname: den Boer
authors.forename: Burkhard W
authors.initials: BW
authors.lastname: Wippermann
authors.forename: Taco J
authors.initials: TJ
authors.lastname: Blokhuis
authors.forename: Peter
authors.initials: P
authors.lastname: Patka
authors.forename: Fred C
authors.initials: FC
authors.lastname: Bakker
authors.forename: Henk J Th M
authors.initials: HJ
authors.lastname: Haarman
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology*; D001696:Biomechanical Phenomena; D016026:Bone Marrow Transplantation; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D016025:Bone Transplantation; D003131:Combined Modality Therapy; D004359:Drug Therapy, Combination; D017886:Durapatite / Q000494:pharmacology*; D005260:Female; D017102:Fracture Healing / Q000187:drug effects* / Q000502:physiology; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology; D006801:Humans; D011859:Radiography; D011994:Recombinant Proteins / Q000494:pharmacology; D012756:Sheep; D013977:Tibia / Q000000981:diagnostic imaging / Q000293:injuries / Q000502:physiology; D014102:Torsion Abnormality; D016212:Transforming Growth Factor beta; D014182:Transplantation, Autologous
chemical_list: C525819:BMP7 protein, human; D001672:Biocompatible Materials; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D017886:Durapatite