Quantitative rates of in vivo bone generation for Bioglass and hydroxyapatite particles as bone graft substitute

Rates of in vivo bone generation were characterized by point-counting analysis of particulate Bioglass and synthetic hydroxyapatite (HA) in rabbit femora. New bony tissue was observed in approximately 20% of the image area around Bioglass particles at 1 wk, and the degree of trabecular bone growth increased with time. The interparticle space of Bioglass was filled by 80% bonding bone between 6 and 12 wk. The rate constants of trabecular bone growth in the presence of Bioglass were approximately 10.9x10(-3) d(-1) at the periphery of the implantation site. HA particles led to smaller rate constants of approximately 4.6x10(-3) d(-1) at the periphery, and the HA particles developed very small amounts of bridging bone. The quantitative rate of bone growth matched well with previously measured bioactive indices of the materials.