The product recall of Desmarquest Zirconia heads in 2001 was associated with specified batches of material. Despite of this fact, concerns raised over the stability of Zirconia led to a vast decrease in the use of Zirconia for hip prostheses. While there is evidence in the literature suggesting that Zirconia may become unstable, there remain many prostheses with Zirconia heads in use today. The purpose of this study was to report the condition observed in retrieved Zirconia heads not included in the product recall.

The bearing surfaces of seven retrieved 22mm diameter Zirconia on UHMWPE hip prostheses were investigated to determine whether any degradation of the Zirconia occurred in-vivo. All seven of the Zirconia heads were manufactured by Saint-Gobain Cerammiques Avancees Desmarquest and implantation time varied from 1 to 10 years. Components were analysed by Talysurf, Interferometer, SEM and XRD and compared to new components.

Talysurf of the components revealed an average surface roughness ranging from 0.004 to 0.007 micrometers Ra. This was only slightly rougher than new ceramic components which generally have an Ra of 0.003 micrometers. SEM of the surfaces did not reveal any difference between the retrieved components and new components. Further surface XRD of 4 of the 7 heads, as shown in Figure 1, showed very small percentages of monoclinic phase (28 degrees 2 theta) with predominantly tetragonal phase (30 degrees 2theta), similar to what is observed in new components. Figure 1: XRD of typical retrieved ZR head surface.

All seven retrieved heads demonstrated no evidence suggesting that degradation of the Zirconia had occurred in-vivo.