Biocompatibility and Osteoconductive Effect of Hydroxyapatite-Tricalcium Phosphate Composite in a Rabbit Femoral Condyle Model

Purpose: Bone grafting is always used in the treatment of bone defects. However, bone harvesting may cause postoperative complications and sometimes does not provide a sufficient quantity of bone. To avoid this adverse issue, we used a synthetic biomaterials as an alternative to autogenous bone grafts in an animal experiment. The objective of this study was to evaluate the repair of bone defects in a rabbit femoral condyle defect model by consisting largely hydroxyapatite (HA) or hydroxyapatite and tricalcium phosphate (HA/TCP) cement mixture. Materials & Methods: One 6-mm diameter defect was made at the lateral condyle site on either side of leg in 12 rabbits and filled with these two kinds of bioceramic material. The rabbits were separately killed at 1 and 3 months after surgery and tissue samples were analyzed by radiography and histology. Results: By the first month, the defects filled with HA grafts or HA/TCP bioceramic material showed similar volumes of bone tissue ingrowth within the defect. The difference in the volume of bone at 3 months between the two groups was statistically significant, revealing a better osteoconductive effect in the SinboneHT group than in the Sinbone group. Conclusions: Hydroxyapatite and tricalcium phosphate (HA/TCP) and hydroxyapatite (HA) implanted in the bone defects all facilitated new bone formation. The amount of new bone formation in HA/TCP was more than that of HA. Thus an HA-TCP composite is a good choice of bone defect filler.