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.