The effect of titanium plasma-sprayed implants on trabecular bone healing in the goat.

The bone response to different titanium plasma-sprayed implants was evaluated in a goat model. Therefore, beam-shaped implants were installed into the trabecular femoral condyles of 10 goats. These implants were provided with three different titanium plasma-sprayed coatings (Ti2, Ti3 and Ti4) with a Ra of 16.5, 21.4 and 37.9 microm, respectively. An Al2O3 grit-blasted implant (Ti-un) with a Ra of 4.7 microm was used as control. After an implantation period of 3 months, the implants were evaluated histologically and histomorphometrically. Only one implant (Ti3) was not recovered after the evaluation period. Light microscopy showed a limited amount of bone for the various implants. Most of the implants showed a different degree of fibrous tissue alternating with direct bone contact. Complete fibrous encapsulation of the implants was observed in some of the sections. No signs of delamination of the plasma-sprayed coating was visible. No significant difference in bone contact were measured between the different types of implants (P > 0.05). Histomorphometrical analysis revealed significantly higher bone mass close to the implant (0-500 microm) for the Ti3, Ti4 and Ti-un implants placed in the medial femoral condyle and the Ti4 implants placed in the lateral condyle. At distance (500-1500 microm), no difference in bone mass measurements between the different implants was observed (P > 0.05).