New Bone Implants Baked to Withstand Stress

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New Bone Implants Baked to Withstand Stress
By medinews.com staff writers
Posted on Engineers can now produce complex bone components with the aid ofrapid prototyping technology, developed initially for thelightweight construction industry.

Researchers at the Fraunhofer-Gesellschaft Institute (Munich,Germany) used a rapid prototyping simulation program to calculatethe internal structure and density distribution of bone material.They were then able to derive the material structure needed forother components, thus calculating and simulating how the structureneeds to be built from different materials in order to meet thespecified requirements. The method allows the engineers to produceparticularly lightweight components--customized for eachapplication--that are also extremely robust. The procedure involvescoating surfaces with wafer-thin layers of specialized metallicpowders. A laser beam then heats (or sinters) the powdered metal inthe exact places that need to be firmer.

The researchers have further enhanced the process to the pointwhere they can actually change the internal structure of the partsafter production by means of precision drilling. This makes thetechnique very attractive to a number of industries, includingaircraft, automobile, lightweight construction industry, andmachine manufacturers. Among them are also manufacturers of boneimplants, who can now produce individual implants with an internalstructure that resembles the patient's bone. Metallic powders madeof biomaterials such as titanium and steel alloys make it possibleto reconstruct other bone elements, such as parts of the knee.

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

Basic bone structure is composed of the cortical (outer layer) ofbone, which forms 80% percent of skeletal bone mass. The cancellousbone--also called trabecular bone--is an inner spongy structurethat resembles honeycomb, and accounts for the remaining 20% ofbone mass. This spongy meshlike bone is designed for strength,similar to steel rods within a concrete structure; the combinationof firm and compact bone in certain places and very porous bone inothers helps bone withstand extremely heavy loads.
Related Links: Fraunhofer-Gesellschaft Institute