Osteoinductive Potential of Porous Calcium-Phosphate Ceramics: Pilot Evaluation in Porcine Femoral Muscle

We aimed to evaluate the ectopic bone formation of porous calcium-phosphate ceramics with different compositions and porous structures following implantation into porcine femoral muscle to understand the factors contributing to osteoinduction.Porous hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) ceramics were fabricated by firing calciumphosphate fiber mixed with carbon beads.Three types of porous calcium-phosphate ceramics were fabricated for animal testing: porous HAp ceramics with 150 μm carbon beads (HAp(150)), and porous β-TCP ceramics with either 20 μm or 150 μm carbon beads (TCP(20) and TCP(150)).Individual porous calcium-phosphate ceramics were implanted into porcine femoral muscle.After 13 weeks, histological evaluation was performed.Ectopic bone formation was observed in HAp(150) and TCP(150).Multinucleated cells were present adjacent to the newly-formed bone.These findings suggested that sufficient interconnection size, large enough for monocyte infiltration, may be an important factor for graft materials to express osteoinduction.