Fabrication of octacalcium phosphate foam through phase conversion and its histological evaluation

Octacalcium phosphate (OCP) foam with an interconnected porous structure was fabricated through phase conversion via a dissolution-precipitation reaction using calcium sulfate hemihydrate (CSH: CaSO4·1/2H2O) granules as precursors in a sodium dihydrogen phosphate (NaDP: NaH2PO4) solution. The diametral tensile strength and porosity of the OCP foam were 0.15 ± 0.04 MPa and 69.4% ± 0.04%, respectively. When the OCP foam was implanted into bone defects in a rabbit femur, the OCP foam showed an excellent tissue response, and the bone penetrated into the porous structure. The osteoconductivity and bone-replacement rate were significantly higher than those of an OCP compact.