Replacement of segmental bone defects using porous bioceramic cylinders: Abiomechanical and X-ray diffraction study

A porous ceramic material [hydroxyapatite-tricalcium phosphate (HA-TCP)] wa s implanted in the femora of 30 dogs to investigate the possibility of usin g this material to repair segmental bone defects. A bone segment, 1.5 cm in length, was removed from the diaphysis of one femur in each dog to create the defect. Cylinders of corresponding size were inserted into the defects. The animals were divided into three groups with recovery times of 2 months , 4 months, and 6 months, respectively. The implants were harvested and sub jected to biomechanic tests (bending strength) and X-ray diffraction analys is. The bending strengths of the implant construct increased gradually over time postoperatively. The values of strength for the three different time groups had significant variations (p < 0.05). The X-ray diffraction analysi s indicated that the peaks of the TCP included in the cylinders decreased i n intensity after implantation and tended to be similar to those of natural bone by 6 months after operation. Conversely, the peaks for the HA had few er changes compared with preimplantation values. Based on the results of th is experiment it was concluded that the porous HA-TCP ceramic cylinders hav e potential for repair of segmental bone defects if assisted by adequate st abilizing fixtures during the early postoperative period. (C) 2000 John Wil ey & Sons, Inc. J Biomed Mater Res 54: 407-411, 2001.