Histologic investigation of the biologic behavior of different hydroxyapatite plasma-sprayed coatings in rabbits

The aim of this study was to investigate bone response to and biostability of three different hydroxyapatite (HA)‐coatings. Therefore, coated and uncoated titanium implants were inserted into the tibia of rabbits. Implantation times were at 3 and 12 weeks. The histological evaluation included measurement of the amount of bone apposition to the various implant surfaces. The results demonstrated at 3 and 12 weeks no marked differences in bony reaction at the cortical level to the different implant materials. However, compared with the 3‐week specimens, at 12 weeks extensive maturation of the woven bone callus had occurred. In addition, all 12‐week implants induced bone formation in the medullary cavity. It was also noted that all HA‐coatings showed loss of coating thickness. Quantitative determination of bone contact demonstrated that all 12‐week implants showed the same high amount of bone apposition. © 1993 John Wiley & Sons, Inc.