Combustion Synthesis Porous Nitinol for Biomedical Applications

Area of Science:

• Biomaterials Engineering
• Orthopedic Research
• Materials Science

Background:

• Porous Nitinol offers a tunable elastic modulus to match bone stiffness, minimizing stress shielding.
• Combustion synthesis (CS) enables the production of a 3D anisotropic interconnective open pore structure.

Purpose of the Study:

• To evaluate the production and performance of porous Nitinol for orthopedic applications.
• To assess the biocompatibility and osseointegration capabilities of porous Nitinol.

Main Methods:

• Porous Nitinol was fabricated using combustion synthesis (CS) of Nickel (Ni) and Titanium (Ti) powders.
• Characterization included mechanical testing (elastic modulus), microstructural analysis, and corrosion resistance evaluation.
• In vivo studies in ovine models (tibia and lumbar spine) assessed osseointegration and bone ingrowth.

Main Results:

• Porous Nitinol exhibited an elastic modulus of ~1 GPa at 60% porosity with pore sizes of 100-500 µm.
• The material showed excellent corrosion resistance (>750mV breakdown potential) and was free of Ni metal or Ni-rich phases.
• Ovine studies demonstrated rapid osseointegration (2 weeks) and complete bone growth across implants (6 weeks), with complete bone through-growth in spinal fusion models (4 months).

Conclusions:

• Porous Nitinol is a promising biomaterial for orthopedic implants due to its mechanical properties, biocompatibility, and exceptional osseointegration.
• The material's ability to promote rapid healing and long-term fixation supports its use in diverse orthopedic applications, including spinal fusion.