Spectrometral and histopathological evaluation of metal ion levels in soft tissue around uncemented implants collected during revision hip replacement.

Abstract Background The aim of the study was to measure metal ion concentration (Ti, Co, Cr, Mo, Ni, Al) around loosened uncemented hip implants and to compare their levels around the cups and steams. Methods Soft tissue samples were collected for analysis in 25 patients (25 hips) during revision hip arthroplasty for aseptic loosening in the years 2007-2009. All tissues collected during the revision arthroplasty were submitted for analysis under a light microscope and ICP –MS analysis. All tissues displayed “foreign body” type chronic inflammatory infiltration with PE and/or metal deposits and metallic inclusions. Results The Inductively Coupled Plasma Mass Spectrometry study of cementless hip implants revealed that the metal ions pass from loose elements of the implants to the surrounding tissues in significant concentrations ranging from a few hundred to several thousand μg / kg. Moreover, the tissues surrounding the loosened cups contained significantly higher concentrations of Ti and Ni metal ions than the tissue surrounding the steams. Conclusions Of all the metal ions used for construction of hip implants, the highest tissue concentration was noted in the case of Ti ions. In any case, regardless of the type of endoprosthesis, the concentrations of Ti and Ni metal ions were higher in tissues surrounding the cup rather than around the stem.