Biomechanical study on repairing bone defect with composite of bovine bone morphogenetic protein and porous hydroxyapatite

To investigate the mechanical property (shear strength, bending strength and compressive strength) and the interface combinative ability of the composite of bovine bone morphogenetic protein (bBMP) and porous hydroxyapatite (HA) with different pore diameter. HA(1) (Phi 100-300 mu m) and HA(2) (C Phi 130-500 mu m) were used as carriers of bBMP(5mg). The 4 types material (HA(1), HA(2), bBMP /HA(1), bBMP /HA(2)) were implanted into the femur of 10 dogs (2 dogs each group) for the shear test and 15 dogs (3 dogs each group) for the bending test and compressive test. The shear strength of all kinds of materials were increased as time went on and the shear strength of bBMP/HA(1) was highest in four materials. The bending strength of bBMP /HA(1) was close to the normal femur in the 201 week. The compressive strength of all materials was lower than the cortex of the dog's femur until 24(th) week. The compressive strength of bBMP /HA(1) was the highest in four types. The compressive strength of HA(2) and bBMP /HA(2) was decreased after implantation. Implant of bBMP /HA with 100-300 mu m diameter had strong bonding with the host bone, and had better mechanical properties than that with 130-500 mu m diameter. So the porous bBMP /HA (Phi 100-300 mu m) could be a useful graft material due to its strength.