| abstract |
This invention relates to a biojoint prosthesis comprising: a) a prosthetic comprising a first component, such as a femural head, having an outer surface comprising at least 90 mol % zirconia, and b) a second component, such as an acetabular cup, having a surface comprising a ceramic such as alumina, shaped to receive the outer surface of the first component, wherein the outer surface of the first component is received on the surface of the second component, and wherein (i) at least a portion of the surface of the second component receiving the first component comprises a ceramic having a surface roughness of no more than 100 nm, and (ii) the outer surface of the first component has a surface roughness of no more than 100 nm. Maintaining the surface roughness Ra at each surface below 100 nm substantially prevents surface damage nucleation when the articulation is in the low force regime common to hip joint prosthesis articulating surfaces. To attain low wear rates, surfaces are made smooth. Controlling the surface roughness of each surface to less than 15 nm reduces wear even more significantly. |