Porosity-graded hydroxyapatite ceramics to replace natural bone.

Porous hydroxyapatite HA bodies were prepared with an aim to simulate bone tissue morphology. By varying the characteristics of starting HA powders and the impregnation strategy of cellulosic sponges with rheologically optimized slurries, a wide range of physico-chemical and mechanical properties of the porous ceramics can be obtained. The samples were characterized microstructurally, by density and porosimetry and by mechanical strength. Cylindrical specimens exhibiting a porosity gradient showed a promising behaviour after implantation in rabbits' femur: newly formed bone grew in tight contact with the ceramic in a very short time, no modified cells are induced and bone tissue fills even the inner pores.