Interfacial study of some inert and active ceramics implanted in bone

Cylinders of biologically inert (Alumina and Zirconia) and active (Hydroxyapatite, Bioglass and AKRA 15 glass) ceramics, were inserted as a press-fit for 6 and 12 months in the femurs of adult Merinos sheep. It resulted that all the cylinders were surrounded by an envelope of new cortical bone; however those made up of inert ceramic were separated from the bone by a capsule of loose connective tissue, whereas a direct contact occurred between the new formed bone and the active ceramics cylinders, except for AKRA 15 rods whose surfaces appeared to be almost compietely covered by fibrous tissue. A bidirectional flow of ions occurred in the outer reactive layer of the two glasses examined. The results are discussed in relation with the biological behaviour of the tested materials in bone implants