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New material that mimics bone may create better biomedical implants
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Researchers at North Carolina State University have developed a “metal foam” that has similar elasticity to bone and could lead to a new generation of implants that avoid bone rejection.
The foam is lighter than solid aluminum and can be made of 100% steel or a combination of steel and aluminum, according to a paper scheduled to be published in Materials Science and Engineering: A.
The paper highlights the “extraordinarily high-energy absorption capability” and light weight of the foam, as well as a modulus of elasticity that the team says is similar to that of bone. The rough surface of the foam is reported to foster bone growth into the implant, according to a North Carolina State University press release.
Modulus of elasticity
Modulus of elasticity determines the load bearing of an implant when placed into bone.
“If the modulus of elasticity of the implant is too much bigger than the bone, the implant will take over the load bearing and the surrounding bone will start to die,” Afsaneh Rabiei, PhD, a study co-author and associate professor of mechanical and aerospace engineering at the university, stated in the release.
“This will cause the loosening of the implant and eventually ends in failure,” she added.
Avoiding stress shielding
Rabiei reported that the modulus of elasticity for the foam is much closer to the 10 to 30 GPa of natural bone than the 100 GPa of titanium. She attributed the light weight of the foam to its porous nature.
Commenting on the ability of the foam to avoid taking on too much load bearing from the surrounding bone, Rabiei stated, “Our composite foam can be a perfect match as an implant to prevent stress shielding.”
- References:
Vendra L, Rabiei A. Evaluation of modulus of elasticity of composite metal foams by experimental and numerical techniques. To be published in the March 2010 issue of Materials Science and Engineering A.
www.ncsu.edu
