Characterisation of Titanium Prosthesis Manufactured with Powder Metallurgy

Abstract

In the present work, a characterisation project around the EVANS wedges manufactured by AMES Medical was developed. The mechanical properties were quantified as well as some morphological parameters and other chemical and bioactive characteristics. The main goal of this thesis is to characterise the fatigue endurance of the final EVANS wedge product made of OsteoSinter®, a titanium porous structure manufactured by AMES Medical using the space holder method. For this study, half of the product samples received a thermochemical Kokubo treatment in order to determine if the treatment, that provides an increase in bioactivity, had any substantial effect on the mechanical properties such as the fatigue endurance capacity. It has also been under observation if the Kokubo thermochemical treatment causes any unsuitable effect. First, a morphological and chemical characterization has been done. SEM-EDS and Raman analysis was performed to confirm the presence of sodium titanates layer in samples treated with Kokubo. Also Mercury Intrusion Porosimetry (MIP) was carried out to determine the micro and macroporosity of titanium structures. In addition confocal observations were also done in order to characterise the surface roughness of the samples. Finally quasi-static compressions, hysteresis compression and fatigue compression-compression tests were performed in order to mechanically characterize the sample. In order to fulfil these goals SEM has been widely used to analyse the samples after mechanical tests Sample testing has shown that the Kokubo treatment has not had a decisive effect on fatigue endurance. Nevertheless all the samples overcame the fatigue tests surpassing 5 million cycles with a deformation under 1.5 mm, the load used has been 3600N and lower. SEM observations have also shown that cracks use pores to spread wider but Kokubo samples did not have any important difference when it comes to crack amount.It can be said that Kokubo treated EVANS wedges do not suffer any important decrease of its mechanical properties when treated and therefore, it is considered an advantage use Kokubo thermochemical treatment in order to improve their osteointegration.