Titanium Foam Past Present Future: State of the Art

The porous structure needs to be interconnected (raw diameter of 300 µm) to promote vascularization. In order to promote some soft tissue ingrowth, roughness has to reach some right order of magnitude, i.e., between 1 and 10 µm. The stress/strain relation of the bone should not be affected by the scaffold. Even if bulk titanium is widely used in the biomedical field, it will not be a good candidate for such an application. The bulk material’s Young’s modulus is too high and the surface is bio-inert. Usually used in the aeronautic field, the porous form can be a good alternative: the foam’s Young’s modulus being much lower than bulk titanium’s one. This could help avoid stress shielding. The foam’s interconnected pores are also adapted to the bone’s ingrowth and will give better mechanical anchors to the implant. This article gives an overview of the results of titanium foam on the biomedical field, especially on 3 different topics: 1—the different manufacturing processes and the properties of the resulting foam; 2—the surface treatments available and their advantages and drawbacks; 3—the tribocorrosion behavior of the foam and the different parameters influencing the results. The need to control the porosity and the evolution of the mechanical properties of the bones depending on the gender and age of the patient are in favor of a tailor-made foam. Additive manufacturing may be a solution to those issues.