New Bone Implants Baked to Withstand Stress

Engineers can now produce complex bone components with the aid of rapid prototyping technology, developed initially for the lightweight construction industry.

Researchers at the Fraunhofer-Gesellschaft Institute (Munich, Germany) used a rapid prototyping simulation program to calculate the internal structure and density distribution of bone material. They were then able to derive the material structure needed for other components, thus calculating and simulating how the structure needs to be built from different materials in order to meet the specified requirements. The method allows the engineers to produce particularly lightweight components--customized for each application--that are also extremely robust. The procedure involves coating surfaces with wafer-thin layers of specialized metallic powders. A laser beam then heats (or sinters) the powdered metal in the exact places that need to be firmer.

The researchers have further enhanced the process to the point where they can actually change the internal structure of the parts after production by means of precision drilling. This makes the technique very attractive to a number of industries, including aircraft, automobile, lightweight construction industry, and machine manufacturers. Among them are also manufacturers of bone implants, who can now produce individual implants with an internal structure that resembles the patient's bone. Metallic powders made of biomaterials such as titanium and steel alloys make it possible to reconstruct other bone elements, such as parts of the knee.

"It's like baking a cake,” said Andreas Burblies, spokesman for the Fraunhofer numerical simulation of products and processes alliance. "Any remaining loose powder is subsequently removed. The end product is an open-pored element; each point possesses exactly the right density and thus also a certain stability.”

Basic bone structure is composed of the cortical (outer layer) of bone, which forms 80% percent of skeletal bone mass. The cancellous bone--also called trabecular bone--is an inner spongy structure that resembles honeycomb, and accounts for the remaining 20% of bone mass. This spongy mesh–like bone is designed for strength, similar to steel rods within a concrete structure; the combination of firm and compact bone in certain places and very porous bone in others helps bone withstand extremely heavy loads.


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Fraunhofer-Gesellschaft Institute