Choi S, Liu IL, Yamamoto K, et al.
We investigated biodegradability and new bone formation after implantation of tetrapod-shaped granular artificial bone (Tetrabone(R)) or beta-tricalcium phosphate granules (beta-TCP) in experimental critical-size defects in dogs, which were created through medial and lateral femoral condyles. The defect was packed with Tetrabone(R) (Tetrabone group) or beta-TCP (beta-TCP group) or received no implant (control group). Computed tomography (CT) was performed at 0, 4 and 8 weeks after implantation. Micro-CT and histological analysis were conducted to measure the non-osseous tissue rate and the area and distribution of new bone tissue in the defect at 8 weeks after implantation. On CT, beta-TCP was gradually resorbed, while Tetrabone(R) showed minimal resorption at 8 weeks after implantation. On micro-CT, non-osseous tissue rate of the control group was significantly higher compared with the beta-TCP and Tetrabone groups (P<0.01), and that of the beta-TCP group was significantly higher compared with the Tetrabone group (P<0.05). On histology, area of new bone tissue of the beta-TCP group was significantly greater than those of the Tetrabone and control groups (P<0.05), and new bone distribution of the Tetrabone group was significantly greater than those of the beta-TCP and control groups (P<0.05). These results indicate differences in biodegradability and connectivity of intergranule pore structure between study samples. In conclusion, Tetrabone(R) may be superior for the repair of large bone defects in dogs.