Mechanical Properties of Titanium–Nickel Foams for Reconstructive Orthopaedics

Pure titanium and some of its alloys are widely used as implant materials under load-bearing conditions in den-tistry and orthopaedics. Titanium and some titanium al¬loys are better received by human tissue when compared to the receptivity of other metal materials. Because of their excellent mechanical properties, low density and bio-compatibility, titanium foams are attractive for structural and biomedical applications. In this work 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 and compressive fatigue. The foams obtained had an appropriate range of pore sizes and interconnectivity, which enabled 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 7.4 MPa at 110 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.