Tribocorrosion behavior at the taper–trunnion interface of artificial hip prostheses with different femoral head materials

The tribocorrosion damage at the taper–trunnion interface of the artificial hip prostheses restricts their effectiveness and service life. Existing investigations on the tribocorrosion mechanism primarily relied on simplified ball-on-disk models. They neglected the inherent complexity and uniqueness of the loading and motion condition at the real taper–trunnion interface. This study aimed to use a hip joint simulator to conduct a comparative investigation of the tribocorrosion behavior of Ti6Al4V  femoral stems paired with traditional ball head materials of CoCrMo alloy and zirconia-toughened alumina (ZTA) ceramic as well as with the innovative material zirconium–niobium (ZrNb) cermet, in an attempt to simulate the real physiological conditions. The results indicated that material loss in all three pairings was primarily dominated by wear. The CoCrMo–Ti6Al4V pairing demonstrated the largest material loss, whereas the ZTA–Ti6Al4V and ZrNb–Ti6Al4V pairings demonstrated comparable, but much smaller, material loss. This could be explained by the difference in variations in the wear and corrosion behavior among different material pairings. Further, the CoCrMo–Ti6Al4V pairing led to galvanic corrosion, thereby increasing the corrosion susceptibility. ZTA ceramic and ZrNb cermet with electrical insulation properties maintained a lower corrosion susceptibility. The ZTA–Ti6Al4V and ZrNb–Ti6Al4V pairings demonstrated a similar material loss in terms of mechanical wear, which was slightly lower than that with the CoCrMo–Ti6Al4V pairing. The relatively low hardness of CoCrMo alloy made it susceptible to the plowing effect induced by oxides during tribocorrosion, leading to substantial material loss and damage. Conversely, ZTA ceramic and ZrNb cermet ball heads showed significantly limited damage due to their higher hardness. Thus, the CoCrMo–Ti6Al4V pairing demonstrated a much higher wear-induced material loss. In conclusion, the tribocorrosion performance of ZTA–Ti6Al4V and ZrNb–Ti6Al4V pairings was comparable and significantly superior to that of CoCrMo–Ti6Al4V pairing.