Identification of wear particles from joint prostheses in tissues by lasermicroprobe mass analysis (LAMMA)

The definite identification of wear particles from joint prostheses is of g reat importance for the development of joint replacement, as the type and q uantity of different wear particles gives information on the wear resistanc e of implant materials. From the types of prostheses nowadays in use polyet hylene wear of the sockets, bone cement wear, metallic and ceramic wear can be generated. Whereas polyethylene wear can be easily identified by its br ight luminescence in polarized light and its characteristic configuration, the distinction of the small granular wear particles of the bone cement, me tal and ceramic by light microscope is difficult. The laser microprobe mass analysis (LAMMA) is a method, which allows the analysis of single light mi croscopically detectable wear particles in tissues. Not only contrast mediu m particles of the bone cements (zirconium oxide or barium sulfate) but als o metallic and aluminum oxide particles could be definitely identified with in the pseudocapsules as well as in regional lymph nodes by LAMMA-analysis, whereby the bone cement wear predominated. In addition, the distinction be tween organic substances (as blood degradation products), which may appear similar to wear particles in configuration and colour, and the foreign mate rial is also possible with this method.