New 'metal foam' that mimics bone can offer better biomedical implants

Washington, Feb 17 (ANI): American scientists have developed a new "metal foam" that mimics bone and can help create better biomedical implants.

Rigid implant materials like titanium often lead to bone rejection, but according to researchers at North Carolina State University, their metal foam is even lighter than solid aluminum and can be made of 100 percent steel or a combination of steel and aluminum.

In a new paper, which will be appear in the March issue of Materials Science and Engineering A.

The researchers claim the "modulus of elasticity" - measurement of a material's ability to deform when pressure is applied and return to its original shape on removal of pressure - of the foam is very similar to that of bone.

"When an orthopedic or dental implant is placed in the body to replace a bone or a part of a bone, it needs to handle the loads in the same way as its surrounding bone," Dr. Afsaneh Rabiei, an associate professor of mechanical and aerospace engineering and an associate faculty member of biomedical engineering at NC State and co-author of the paper.

Rabiei added: "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. This will cause the loosening of the implant and eventually ends in failure. This is known as "stress shielding". When this happens, the patient will need a revision surgery to replace the implant. Our composite foam can be a perfect match as an implant to prevent stress shielding."

To give an idea of the difference between the modulus of elasticity of bone and that of traditional implants, bone has a modulus of between 10 and 30 GPa - while titanium has a modulus of approximately 100 GPa. The new composite foam has a modulus that is consistent with bone, and is also relatively light because it is porous.

Rabiei said the rough surface of the metal foam, "will bond well with the new bone formed around it and let the body build inside its surface porosities. This will increase the mechanical stability and strength of the implant inside the body."

The research, "Evaluation of modulus of elasticity of composite metal foams by experimental and numerical techniques," was funded by the National Science Foundation.

It will appear in the March issue of Materials Science and Engineering A. (ANI)