The effect of warfarin on the attachment of bone to hydroxyapatite-coated and uncoated porous implants.

The attachment of bone to hydroxyapatite-coated and uncoated porous implants made of cobalt-chromium-molybdenum alloy was investigated with and without postoperative administration of warfarin sodium. The implants were placed transcortically in the femoral diaphysis of adult female goats and were evaluated after three, six, and twelve weeks in situ. Mechanical push-out testing and histological evaluation revealed that the attachment strength and the ingrowth of bone at the bone-implant interface increased with time in situ for both the hydroxyapatite-coated and the uncoated implants. The administration of warfarin significantly impaired both the attachment strength and the ingrowth of bone at twelve weeks. At twelve weeks, the attachment strength and bone ingrowth of the hydroxyapatite-coated implants in the animals that had received warfarin were statistically equal to those of the uncoated implants in the control animals.