In-vivo degradation mechanism of Ti-6Al-4V hip joints

The degradation mechanism was concluded to be of combined mechanical and chemical nature. Wear debris is formed and accumulated in large flakes (> 100 μm). Upon further sliding the flakes are pressed into the surface and ultimately crushed into small, brittle particulate debris (< 5 μm), which is released from the surface. It is suggested, that the small brittle particulate debris has a more detrimental effect in the hip joint than the large flakes due to a stronger reaction of the peri-prosthetic tissue. Also, Al-oxide particles are formed as part of the degradation mechanism.