Potential Bone Replacement Materials Prepared by Two Methods

Natural and synthetic hydroxyapatite (HA) scaffolds for potential load-bearing bone implants were fabricated by two methods. The natural scaffolds were formed by heating bovine cancellous bone at 1325°C, which removed the organic and sintered the HA. The synthetic scaffolds were prepared by freeze-casting HA powders, using different solid loadings (20–35 vol.%) and cooling rates (1–10°C/min). Both types of scaffolds were infiltrated with polymethylmethacrylate (PMMA). The porosity, pore size, and compressive mechanical properties of the natural and synthetic scaffolds were investigated and compared to that of natural cortical and cancellous bone. Prior to infiltration, the sintered cancellous scaffolds exhibited pore sizes of 100 – 300 μm, a strength of 0.4 – 9.7 MPa, and a Young’s modulus of 0.1 – 1.2 GPa. The freeze-casted scaffolds had pore sizes of 10 – 50 μm, strengths of 0.7 – 95.1 MPa, and Young’s moduli of 0.1 –19.2 GPa. When infiltrated with PMMA, the cancellous bonePMMA composite showed a strength of 55 MPa and a Young’s modulus of 4.5 GPa. Preliminary data for the synthetic HA-PMMA composite showed a strength of 42 MPa and a modulus of 0.8 GPa.