Abstract
In 1995, A. Fujisawa et al. had reported the development of unique cementless total hip joints applying hydroxyapatite (HA) flame coating onto the porous titanium surface which is arc-sprayed with pure titanium material. The thickness of the HA layer was between 20 and 50 micron meter considering the balance of bone conduction effect of HA and mechanical detachment of the layers from the porous titanium. At that time specific question was raised whether or not the coated HA layers would be existing in the living bone surrounding them.The results obtained from the observation for the retrieved specimens show thickness of HA coating layer is sufficient for the new bone formation after implantation, and HA would be absorbed in the body in a few years after contributing the new bone formation.
