[Comparative surface examinations of morse taper junctions of the MRP-Titan stem shot peened with glass beads]

Shot peening is widely used for surface treatment of hip implants. Shot peening with steel balls followed by a cleaning process with glass beads is used for introduction of negative stress in the production of morse taper junctions of the MRP-Titan stem. An increasing number of publications in maxillofacial surgery and orthopaedic surgery show that there is a significant contamination of Alumina or glass blasted surfaces. Latest research suggested an association between contaminant particles with early loosening of endoprostheses (third body wear). The aim of this study is to evaluate the amount and the effects of surface contamination with glass particles on morse taper junctions of implants and explants of the MRP-Titan stem.

The surface of morse taper junctions of the MRP-Titan stem (5 original-package implants and explants each) are analysed for glass particle contamination. A field emission scanning electron microscopy (LEO 1525) is used for the detection of the glass-particles on the implant surface with a backscattered electron detector. The relative surface area covered by particles was calculated by means of an image analyzing software (analySIS, Soft Imaging System GmbH).

The surface of the implants showed a considerable contamination with glass particles with a mean of 6.67 +/- 0.82% compared to 2.06 +/- 0.74% on the surface of the explants. The difference was statistically significant (p<0.0001).

The results of this study show that there is a relative high percentage of contamination with glass particles on shot peened morse taper junctions of the MRP-Titan stem. This contamination is significantly lower on the surface of the explants. With respect to third body wear and osteolysis in total hip arthroplasty further studies are necessary to minimize contamination while maintaining adequate surface quality.