Histological, mechanical, and radiological study of osteoformation in titanium foam implants

Titanium (Ti) is widely used for implants because of its high mechanical reliability and because it aids osteoformation. However, it also produces artifacts during radiological imaging. Further, Ti implants can sometimes cause the surrounding bone to break. Owing to recent advances, Ti can be transformed into sponge-like, porous materials having a three-dimensional network of pores; such materials are called Ti foams. These foams exhibit distinct characteristics that make them more suitable than nonporous Ti. The objective of this study was to evaluate Ti foams as implant materials.

Implants based on Ti foams having porosities of 80% and 90% were embedded in the femurs of 11 rabbits. Implants based on 0% porosity Ti were used as controls. Five rabbits were sacrificed 4 weeks after implantation, while the remaining were sacrificed after 12 weeks. The femurs containing the Ti implants were harvested and analyzed.

Biomechanical analyses showed that the 80% porosity implants induced greater osteoformation. There were significant differences in the average pushout strengths of the control and 80% porosity implants after 4 weeks (p = 0.048) and 12 weeks (p = 0.001). Histopathological analyses confirmed osteoformation in the case of the 80% porosity implants. Analyses of the micro-computed tomography images of the Ti foam-based implants did not suggest the presence of artifacts.

The 80% porosity Ti implants did not exhibit the shortcomings associated with conventional Ti implants. In addition, they induced greater osteoformation. Finally, the Ti foams did not produce radiological artifacts.