Enhancement of Bone Ingrowth into Porous Coated Titanium by Hydroxyapatite Coating in Experimentally-induced Osteoporosis

The authors studied ingrowth of osteoporotic bone into porous-coated titanium alloy with and without hydroxyapatite (HA) coating in a canine model by resection of the sciatic nerve. Unilateral osteoporosis of the tibia after resection of the sciatic nerve was confirmed by serial radiograph. Titanium porous-coated rods, with and without HA coating, were inserted in press fit in the lateral femoral cortex in 10 dogs. Bone ingrowth after 8 weeks was of equal amounts in non-HA coated and HA coated rods. The HA coatings showed direct osseointegration and ingrowth on its surface and deep fiber-mesh without fibrous tissue, but non-HA coatings showed a thin fibrous layer between the bone and titanium interface. Bone-implant shear strength of the HA coated rods was greater than the non-HA coated rods (28.9 MPa in HA coating rod and 18.2 MPa in non-HA coating rod, P=0.041). The results demonstrate that ingrowth of HA coating on porous-coated implants was superior to non-HA coated ones in osteoporotic bone.restrictio