BONE INGROWTH ANALYSIS AND INTERFACE EVALUATION OF HYDROXYAPATITE-COATED VERSUS UNCOATED TITANIUM POROUS BONE IMPLANTS

Fourteen titanium porous-coated implants with a cylindrical shape (len gth 22 mm and diameter 5 +/- 0.3 mm) were prepared. Bead size was 250- 350 mu m. Seven implants were plasma-sprayed with hydroxyapatite and t he other seven remained uncoated. Implants, both hydroxyapatite-coated and uncoated, were randomly selected and press fitted longitudinally into the proximal femoral cancellous bone bilaterally in seven dogs. A fter 12 weeks the dogs were euthanized and push-out and histomorphomet ric backscattered electron microscopy studies were carried out. No sta tistical differences in the mechanical tests were observed. Comparing hydroxyapatite-coated versus uncoated implants, the histomorphometric results showed statistical significance in the percentage of bone (p = 0.01); and in bone index, ratio between bone ingrowth and bone ongrow th (p = 0.01). The size of the bone implant interface was smaller in t he hydroxyapatite-coated implants than in the uncoated (p = 0.029). Be neficial effects of hydroxyapatite applied to spherical bead titanium porous coatings were demonstrated. These morphological and histomorpho metric results support the concepts involved with the use of hydroxyap atite as a coating for uncemented porous prosthetic devices.