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 bone- PMMA 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.