A comparison of the osteoinductive potential of two calcium phosphate ceramics implanted intramuscularly in goats

The osteoinductive potential, or bone induction potency, of two calcium phosphate ceramics was evaluated after intramuscular implantation in goats. The ceramics were comprised of hydroxyapatite (HA) and biphasic calcium phosphate (BCP), the later of which contained a 85/15 mixture of hydroxyapatite and tricalcium phosphate (TCP). Both ceramics had a similar macroporosity of around 55% and a pore distribution between 100 and 800 microm. Besides the difference in chemistry, BCP was also microporous and hence had a different surface microstructure. After implantation in the back muscles of four goats for 12 weeks, all 8 BCP samples (7x7x7 mm(3)) showed the presence of bone formation in the macropores (1+/-1%), while no bone was found in any of the HA samples. The used BCP can therefore be characterized as an osteoinductive material. Having the ability to induce bone formation in soft tissues, the BCP presented herein may be a useful biomaterial for bone repair when combined with cultured osteogenic cells, growth factors or both.