Behavior of β-tricalcium phosphate granules composed of rod-shaped particles in the rat tibia

Porous spherical granules of β-tricalcium phosphate (β-TCP) composed of rod-shaped particles were prepared via a hydrothermal route. The biological significance of implantation of the spherical β-TCP granules for healing of bone defects was analyzed by implantation into 2 mm diameter and 3 mm deep defects created in tibiae of 9-week-old Wistar rats. Implantation of spherical β-TCP contributed to regeneration of bone tissue. At 2 and 4 weeks after implantation, numerous alkaline phosphatase-positive cells appeared around the implant and newly formed bone. At 8 weeks after implantation, residual implants were mostly embedded in bone tissue. Without implantation, bone defects healed with a much lower amount of bone. In addition, bone marrow adipocytes were considerably fewer in tibiae with implants compared to tibiae without implants at 4 and 8 weeks after the operation. These data suggested that implanted β-TCP granules worked as scaffolds to maintain alkaline phosphatase-positive cells and also resulted in less fatty change of bone marrow.