ZIRCONIUM OXIDE SURFACE LAYERS ON ORTHOPAEDIC DEVICES TO INCREASE LIFETIME

IMPLANTABLE ORTHOPAEDIC FEMORAL COMPONENTS ARE METALLIC BECAUSE OF THE TENSILE FORCES PRESENT. CERAMIC MATERIALS, SUCH AS AL2O3 OR ZRO2, GENERALLY EXHIBIT MANY DESIRABLE PROPERTIES INCLUDING LOWER ION RELEASE, LESS CUP WEAR, AND GOOD BIOCOMPATIBILITY, BUT ARE POOR IN TENSION. COATINGS ARE UNDESIRABLE BECAUSE ADHESION CANNOT BE GUARANTEED. HIGH ENERGY ION IMPLANTATION IS ACCEPTED AS A METHOD THAT CAN PROVIDE THE NEEDED ADHESION BECAUSE THE ATOMS ARE INJECTED WELL BELOW THE SURFACE, RATHER THAN DEPOSITED ONTO IT. A TECHNIQUE FOR GROWING A THICK SURFACE LAYER OF ZRO2 ON ORTHOPAEDIC DEVICES USING ION IMPLANTATION IS DESCRIBED. THE LAYER INTERFACES INTO THE SUBSTRATE THROUGH A BLENDED TRANSITION REGION THAT SPANS A ZONE UP TO 0.1 MICROMETERS IN THICKNESS, ZRO2 LAYERS UP TO THREE MICROMETERS THICK ARE POSSIBLE, PROVIDING A LONG LIFETIME ARTICULATING SURFACE.