Characterisation of alumina nip-joint wear by FIB microscopy

The wear of hip-Joints is a significant clinical problem, which causes adverse tissue reactions leading to bone absorption and consequent loosening of the fixation. Artificial hip joints retrieved after use and tested on simulators typically exhibit a 'stripe' wear area on the surface of the alumina bearing components. Focused Ion Beam (FIB) microscopy has been used to investigate the sub-surface damage mechanisms in worn alumina hip-joints for the first time. The alumina acetabular cup, both inside and outside the 'stripe' wear trace, has been cross-sectioned by FIB milling. The sub-surface microstructures revealed by the FIB machining, outside, inside and at the edge of the 'stripe' have been imaged by SEM and FIB and are compared with the microstructure of unworn bulk material. The advantage of this technique is that it enables site specific selected areas of the worn surface to be analysed.