Back in June, those brainy folks over at Germany’s Fraunhofer research group announced the development of Resobone, a material designed to replace the titanium plates used to patch holes in peoples’ skulls. Now, perhaps a little ironically, they’ve announced the creation of TiFoam – a titanium foam to be used for replacing injured bone. Unlike Resobone, TiFoam is intended for load-bearing areas, where a balance of strength and flexibility are essential. Like Resobone, however, it’s designed to encourage surrounding bone to grow into the implant.
Typically, the more stress a bone has to endure, the thicker and stronger it gets. Traditional titanium bone replacements tend to be stiffer than the bone to which they’re attached, so the implant ends up taking most of the load of activities such as walking, lifting, or even just standing. This results in the bone not having to take as much of that load itself, and thus not retaining its strength. In some cases the bone can even deteriorate, to the point that the implant has to be reattached.
TiFoam, on the other hand, is designed to be as flexible as the adjacent bone. Patients are advised to engage in load-bearing activities immediately after insertion, as these will encourage bone cells and blood vessels to grow into the foam’s interior matrix, incorporating the implant into the skeletal structure.
The material is made by saturating open-cell polyurethane foam with a fine titanium powder and a binding agent. Once the titanium has bonded to the various nooks and crannies, the foam and the binding agent are vaporized. What’s left is nothing but titanium, which is then heated and compressed to form something with a structure very much like that of the spongiosa inside bones.