A prosthesis comprises a femoral stem having a frustoconical femoral neck a femoral head having an articular bearing surface with an outer diameter of 26mm or more, and a frustoconically tapered internal recess and a sleeve comprising a frustoconical body for insertion into the recess of the femoral head and a frustoconically tapered internal recess for receipt of the frustoconical femoral neck. A surface of the recess of the sleeve comprises oxidised zirconium or oxidised zirconium alloy to resist or minimise mechanically assisted crevice corrosion.
