Abstract
Introduction: The present series of studies were performed in order to investigate the effect of hydroxyapatite coating on bone ingrowth into cementless implants when subjected to pathological and mechanical conditions mimicking the clinical situation.
Material & methods and results: Hydroxyapatite (HA) and titanium alloy (Ti) coated implants were inserted into the femoral condyles in mature dogs. The observation period ranged between 4 and 16 weeks and the results were evaluated by mechanical push-out test and histomorphometric analysis.
The HA coating yielded superior effect on bone ingrowth compared to Ti when surrounded by a gap-whereas no effect was found in the press fit situation.
Allogeneic bone graft packed around the implant enhanced the anchorage of Ti implants, but HA coating alone without bone graft offered almost the same improvement in anchorage in 2 mm defects. Only minor improvement was obtained when bone graft was used together with hydroxyapatite.
Another interesting study showed that HA coating was able to prevent polyethylene particles to migrate around the implant by creating a seal of bony ingrowth.
HA coating on a porous surface resulted in significantly stronger fixation compared with HA coating on a grit blasted surface.
A clinical study (using roentgen stereophotogrammetric analysis, RSA) on total hip arthroplasty showed that HA coated femoral components were stable 3 months after surgery whereas migration of Ti coated components continued resulting in significantly less migration of HA coated components at 60 months.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
