Current Concepts in Bone Graft Substitutes

Abstract

Purpose: Bone grafting is still requested to fill bone defects in traumatology, or after tumor removal, but also in orthopedic surgery for spine, arthroplasty revisions, and osteotomies. Due to the limitations of autografts and allografts, and the progress of biomaterial research, a large number of nonhuman bony scaffolds have been developed including synthetic calcium phosphates and highly processed xenografts. The most important parameters for bone ingrowth are the macroporosity of the scaffold with the suitable biological autologous cells and factors, optimal osteoinductive, osteointegrative and osteoconductive properties can be achieved. Methods and Results: The important factors regulating these properties are discussed in this paper, which also reports preclinical and clinical results obtained with such bone graft substitutes. Conclusions: Among different bone graft substitutes available, the porosity, the accessibility of pores, the internal surface exposed to the biological components of bone repair, are present in highly processed bovine hydroxyapatites. Compared to autografts, allografts and synthetic substitutes, they associate an initial conductivity, and a long term stability suitable for some orthopedic indications.

Physical Characterization of Biphasic Materials With Different Granulation Sizes and Their Influence on Bone Repair and Inflammation in Rat Calvaria

“…Xenogeneic grafts, especially inorganic bone matrices of bovine origin, have physicochemical characteristics similar to those found in humans 7,19 . The preservation of the volume of the regenerated area is due to the presence of the particles of this biomaterial in the grafted areas for many years 2,17 .…”

“…Regenerative procedures are performed to correct bone defects caused by pathological processes, dentoalveolar trauma, periodontal diseases, alveolar ridge preservation after tooth extraction, and reconstruction of alveolar processes associated with implant treatments 2,4,7 . The combinations of various surgical techniques are necessary, which are simpli ed by the use of biomaterials, to achieve success in these reconstructive procedures 4,17 .…”

“…The particle size is closely related to the microenvironment created by the insertion and compaction of granules inside bone defects and to the three-dimensional architecture obtained in the initial phase of repair 4,10 . Although highly important for clinical practice, the description of each biomaterial's ideal particle size is not consensual in the literature 7,12 .…”

“…They must have properties that modulate the severity of in ammatory responses to integrate biomaterials into live tissues 4 . Events such as the migration and formation of blood vessels and the adhesion, migration, differentiation, and proliferation of osteoblasts within a three-dimensionally porous scaffold are directly related to the mechanical, biological, physical and chemical characteristics of biomaterials, such as crystallinity, shape and dimensions of particles, rugosity, porosity, and interconnectivity of pores 6,7,8 .…”

Biomechanical Stability and Osteogenesis in a Tibial Bone Defect Treated by Autologous Ovine Cord Blood Cells—A Pilot Study

“…Within the scaffold, the nanopores enable the uptake and retention of large volumes of blood and other fluids. The macropores can act as a conduit allowing movement and adhesion of bone building cells throughout the HA scaffolding and provide the space for blood vessel ingrowth [51]. The resistance to axial compression is 2.5 to 3 Mpa [50].…”