A Study on Porous Titanium Implants by Layer Manufacturing Process

Titanium and titanium alloys have been extensively used in biomedical implants because of their excellent corrosion resistance, good biocompatibilities, reasonable mechanical properties and relatively low elastic modulus. However, the elastic modulus of titanium is still much higher than that of cortical bone. A high elastic modulus of implant may cause stress shielding effect which leads to bone resorption eventually resulting in implant failure or bone fracture. Porous titanium is an alternative to figure stress shielding problem out. Powder sintering, sponge replication and gas foaming/entrapping have been general processing routes to fabricate porous titanium so far. However, it is not easy to obtain the optimum combination between strength and pore structures by the conventional processing routes. Further, conventional foam or trabecular pore structures are not suitable to bone tissue ingrowth. On the contrary, layer manufacturing technology enables three dimensionally controlled designing and shaping of porous body so as to provide good strength and pore space for tissue ingrowth. In the present study, we have fabricated porous titanium with different pore structures by layer manufacturing. Compressive mechanical properties of porous titanium were characterized. In vitro characterization was conducted using L929 fibroblast and MG63 osteoblast-like cells. In vivo study was also carried out to evaluate bone in-growth and regeneration behavior using rat’s calvarial defect model.