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 im plants made of cobalt-chromium-molybdenum alloy was investigated with and without postoperative administration of warfarin sodium. The impla nts were placed transcortically in the femoral diaphysis of adult fema le goats and were evaluated after three, six, and twelve weeks in situ . Mechanical push-out testing and histological evaluation revealed tha t the attachment strength and the ingrowth of bone at the bone-implant interface increased with time in situ for both the hydroxyapatite-coa ted and the uncoated implants. The administration of warfarin signific antly impaired both the attachment strength and the ingrowth of bone a t twelve weeks. At twelve weeks, the attachment strength and bone ingr owth of the hydroxyapatite-coated implants in the animals that had rec eived warfarin were statistically equal to those of the uncoated impla nts in the control animals. CLINICAL RELEVANCE: The administration of warfarin sodium after total joint arthroplasty performed without cemen t may impair the fixation of the implant and the ingrowth of bone. Coa ting of the implant with hydroxyapatite may partially reverse this eff ect.