Affiliations: Policlínica Granollers, Granollers, Barcelona, Spain | CREB, Dpto. Ciencia de los Materiales e Ingeniería Metalúrgica, ETSEIB, Universidad Politécnica de Cataluña, Diagonal 647, 08028-Barcelona, Spain
Note: [] Corresponding author: F.J. Gil, Dept. C.Materiales e Ing. Metalúrgica, ETSEIB, Universidad Politécnica de Catalunya, Diagonal 647, 08028-Barcelona, Spain. Tel.: +34 934016708; E-mail: francesc.xavier.gil@upc.edu.
Abstract: Fifty two ceramic femoral heads have been investigated after implantation. All heads had articulated against ultra high molecular weight polyethylene (UHMWPE) cups. Examination of the heads shows changes in sphericity and surface roughness due to the wear. The behaviour of these retrieved heads after clinical use confirms the problems derived from the use of yttria-stabilised tetragonal zirconia heads. In this paper, a failure mechanism for this type of ceramic is proposed. The slow yttria dissolution produces the transformation from tetragonal to monoclinic phase with a volume change. This fact provokes an important decrease in mechanical properties favouring wear. The yttria dissolution and the zirconia solid transformation were confirmed by X-ray diffraction.
