Titanium Foams Resemble Structural Configuration of Natural Bone

A new titanium material features a foam-like structure. Source: Fraunhofer

A new implant, made of titanium foam, resembles the inside of a bone in terms of its structural configuration. Not only does this make it less stiff than conventional implants, it also promotes ingrowth into surrounding bones. Developed by Fraunhofer, the TiFoam material is the result of a powder metallurgy-based moulding process that has already proven its value in the industrial production of ceramic filters for aluminum casting.

The Ti6Al4V titanium alloy is durable, stable, resilient and well tolerated by the body. But it is somewhat difficult to manufacture: titanium reacts with oxygen, nitrogen and carbon at high temperatures, for example. This makes it brittle and breakable. The range of production processes is equally limited.

There are still no established processes that can be used to produce complex internal structures. This is why titanium implants are often used to repair defects in load-bearing bones. Many of these possess structured surfaces that provide bone cells with firm support. But the resulting bond remains relatively weak. Moreover, the traits of such implants are different from those of the human skeleton: they are substantially stiffer, and, thus, carry higher loads. “The adjacent bone bears hardly any load any more, and even deteriorates in the worst case. Then the implant becomes loose and has to be replaced,” explains Dr.-Ing. Peter Quadbeck of the Fraunhofer Institute for Manufacturing and Advanced Materials IFAM.

Open-cell polyurethane (PU) foams are saturated with a solution consisting of a binding medium and a fine titanium powder. The powder cleaves to the cellular structures of the foams. The PU and binding agents are then vaporised. What remains is a semblance of the foam structures, which is ultimately sintered. “The mechanical properties of titanium foams made this way closely approach those of the human bone,” Quadbeck says. “This applies foremost to the balance between extreme durability and minimal rigidity.” The former is an important precondition for its use on bones, which have to sustain the forces of both weight and motion. Bone-like rigidity allows for stress forces to be transmitted; with the new formation of bone cells, it also fosters healing of the implant. Consequently, stress can and should be applied to the implant immediately after insertion.

More information on the research is available from Fraunhofer.

For other blog posts from medtechinsider on advances in bone replacement materials, see:

Titanium Coating with Protein Nanoclusters Strengthens Implant Attachment

Synthetic Bone Graft Recruits Stem Cells to Facilitate Bone Healing

New Resorbable Compound Facilitates Bone Regeneration

Tags: bone, bone reconstruction, bone replacements, bone research, bone-like material, Fraunhofer, Ti6Al4V, TiFoam Project