Novel multilayer Ti foam with cortical bone strength and cytocompatibility.

Area of Science:

• Biomaterials Engineering
• Orthopaedic Research
• Materials Science

Background:

• Load-bearing orthopaedic implants require mechanical strength and biological fixation.
• Porous materials offer potential for implant applications but often face challenges in balancing porosity and strength.
• Previous work established a novel titanium (Ti) foam sheet using a slurry foaming method.

Purpose of the Study:

• To develop a novel multilayer Ti foam with mechanical properties compatible with cortical bone.
• To enhance biological fixation capabilities through optimized pore structure.
• To address the contradictory requirements of high porosity for cell infiltration and high strength for load-bearing applications.

Main Methods:

• Layer-by-layer stacking of Ti foam sheets with distinct volumetric porosities (80% and 17%).
• Mechanical compression testing to evaluate Young's modulus and yield strength.
• In vitro cell culture studies to assess cell penetration and calcification within the foam structure.

Main Results:

• The multilayer Ti foam achieved a Young's modulus of 11-12 GPa and yield strength of 150-240 MPa.
• Significant cell penetration (1.2 mm within 21 days) was observed in the 80% porosity foam, unaffected by lower porosity layers.
• Calcification was observed, indicating the Ti foam supports bone formation without inhibition.

Conclusions:

• Contradictory requirements for high porosity and high strength were successfully reconciled through role-sharing in multilayered foam sheets.
• The developed multilayer Ti foam exhibits promising characteristics for load-bearing orthopaedic implant applications.
• This novel Ti foam demonstrates potential for improved osseointegration and mechanical performance in orthopaedics.