Foam mimics bone

A titanium foam capable of mimicking the traits of human bone has been created by German scientists, and could be used instead of bulky titanium implants to support injured bones.

Scientists at the Fraunhofer Institute for Manufacturing and Advance Materials – as part of the TiFoam project – have created a foam-like structure that resembles the spongiosa inside human bone. They hope it can be used instead of traditional titanium implants that are stiffer than ordinary bones, and can even cause bones to deteriorate.

The new material is made through a powder metallurgy-based moulding process that is also used in the production of ceramic filters for aluminium casting. Open-cell polyurethane (PU) foams are saturated with a solution of a binding medium and a fine titanium powder, which cleaves to the cellular structures of the foam. The PU and binding agents are vaporised and what remains is a foam structure that is sintered.

“The mechanical properties of titanium foams made this way closely approach those of the human bone,” said Dr Peter Quadbeck who coordinated the research, “This applies foremost to the balance between extreme durability and minimal rigidity.

Quadbeck hopes that this foam could be used especially for those bones which have to sustain weight and movement – both of which can be restricted with bulky titanium bars. The bone-like rigidity of the foam allows for stress forces to be transmitted and the porosity allows new blood vessels and bone cells to form as it would in normal bone.