"Hard on soft" bearings for hip replacements comprise a polyethylene cup and a choice of metal or ceramic femoral head. With over 25 years of clinical use, ceramic femoral heads have been found to reduce the amount of polyethylene wear compared to metal heads. This is because the surface of metal heads become scratched and damaged over time, ceramic on the other hand is extremely hard (only diamond is harder) and is therefore resistant to scratches. More recently "hard on hard" bearings such as ceramic on ceramic have been developed to eliminate polyethylene wear altogether.

Two different ceramic materials are available, alumina and zirconia. Both alumina and zirconia may be used for "hard on soft" bearings, zirconia offers greater design flexibility for smaller diameter and long neck length femoral heads. Your surgeon will be able to explain which ceramic material is best for you.

Alumina is the only clinically proven material for "hard on hard" bearings comprising an alumina femoral head and an alumina cup insert.