Electrostatic surface charge acceleration of bone ingrowth of porous hydroxyapatite/beta-tricalcium phosphate ceramics

Bone ingrowth enhancement by the surface induced charges of the electrically polarized hydroxyapatite (HA)/beta-tricalcium phosphate (beta-TCP) ceramics was histologically investigated to clarify the early stage events of ossification. The HA/beta-TCP specimens with a relatively low porosity of 45%, for bone ingrowth were polarized in a dc electric field at 400 degrees C for I h. The large preserved charges of 8 mu C cm(-2) significantly promoted the bone ingrowth process of the porous ceramics implanted in femoral diaphyses of New Zealand white rabbits. The bone formation in the pores of the polarized HA/beta-TCP specimens was observed within I week after surgery. The bone occupancy of the polarized HA/beta-TCP pores reached more than 90% at as early as 2 weeks and significantly higher than that of the nonpolarized. The electrical polarization was proved to be effective for bone penetration improvement of low porosity ceramics. The electrically polarized HA/beta-TCP bone grafts with a lower porosity and a higher mechanical strength combined high osteoconductivity generated by the induced surface charges. (C) 2009 Wiley Periodicals, Inc. J Biomed Mater Res 92A: 267-275, 2010