Porous HA ceramic for bone replacement: role of the pores and interconnections - experimental study in the rabbit

Hydroxyapatite (HA) porous ceramics are increasingly used in biomedical applications. Their physical characteristics, such as porous volume, require perfect control of the pore shape, as well as the number and the size of their interconnections. The aim of our study was to evaluate a new HA ceramic using polymethylmethacrylate microbeads (PMMA) as the porous agent. Four interconnection sizes (30, 60, 100 and 130 microm) with a 175-260 microm pore size and three pore sizes (175-260, 260-350 and 350-435 microm) for a 130 microm interconnection size were tested. Various HA implants were appraised by microscopic evaluation in a 4.6 x 10 mm rabbit femur cancellous bone defect 12 weeks after implantation. The best osteoconduction result was obtained in the center of the ceramic by means of a 130 microm interconnection size and a 175-260 microm mean pore size. Bone formation obtained within the pores was double that obtained in our previous study where naphtalen microbeads were used as the porous agents.