Metal foam : New material that mimics bone may create better biomedical implants

Orthosupersite
North Carolina State University Researchers developed a “METAL FOAM”  having similar elasticity to bone heading to a new generation of implants that avoid bone rejection.
Characteristics:
- lighter than solid aluminum

- made of 100% steel or a combination of steel and aluminum
- “extraordinarily high-energy absorption capability”
- light weight
- modulus of elasticity similar to that of bone.
- its rough surface  foster bone growth into the implant

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,”
- “This will cause the loosening of the implant and eventually ends in failure.

Avoiding stress shielding

- modulus of elasticity for the foam is much closer to the 10 to 30 GPa of natural bone than the 100 GPa of titanium.
- light weight of the foam is attributed to its porous nature.
- on ability of the foam to avoid taking on too much load bearing from the surrounding bone “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