Impact of biphasic calcium phosphate bioceramics on osteoporotic hip bone mineralization in vivo six months after implantation

Calcium phosphate bone substitutes are successfully used for local recovery of osteoporotic bone and filling of bone defects. Previous studies reveled that biphasic calcium phosphate (BCP) show better bioactivity in compare to pure calcium phosphate (CaP) or hydroxyapatite (HAp). Also increased porosity of material promotes better bone tissue response. Aim of this experiment was to evaluate immunohistologically response of osteoporotic bone of experimental animal to implantation of granules with hydroxyapatite/β-tricalcium phosphate (HAp/β-TCP) ratio of 90/10. CaP was synthesized by aqueous precipitation technique from calcium hydroxide and phosphoric acid and sintered granules in size range from 1.0 to 1.4 mm were prepared with pore sizes around 200 nm. Nine female rabbits with induced osteoporosis were used in this experiment. Six animals in study group underwent implantation of BCP in hip bone defect and three animals in control group left without BCP implantation. After 6 months animals were euthanized, bone samples collected and proceeded for detection of bone activity and repair markers: osteocalcin (OC), osteopontin (OP) and osteoprotegerin (OPG). Controls demonstrated the presence of experimental bone osteoporosis. In experimental group bone showed partially resolved bioceramic material and in some samples new bone formation near the granules was observed. Increase of OC and OPG up to twice as to compare to control group were detected as well. Implantation of BCP HAp/βTCP 90/10 bioceramic in osteoporotic rabbit bone increases expression of OC and OPG indicating the activation of osteoblastogenesis and bone mineralization in vivo.