Mechanical properties of nickel–titanium foams for reconstructive orthopaedics

Porous NiTi materials were obtained in order to allow the ingrowth of living tissue, thus increasing the mechanical anchorage of implants. This promotes long-term fixation without the need for bone grafting. This study focuses mainly on the determination of mechanical properties: compression, bending and compressive fatigue. The foams obtained had an appropriate range of pore sizes and interconnectivity, which enabled a morphology similar to that of bone to be achieved. Their mechanical properties proved to be highly compatible with those of bone (an elastic modulus similar to that of cancellous bone), and the compressive fatigue limit was 7.5 MPa at 107 cycles with samples exhibiting significant plastic deformation. SEM examination showed cracking at strut junctions 45° to the axis of the applied load. The results indicate that the material provides structural support while bone ingrowth is taking place.