Update on endoprosthesis pathology: Particle algorithm for particle identification in the SLIM

When it comes to endoprosthesis pathologies, for example, implant-allergic/toxic problems, as a cause of implant failure, particle identification has an important role to play in the histopathological diagnostics of the neosynovial/periprosthetic membrane (synovial-like interface membrane, SLIM). The variability of materials in endoprosthetics and differences in particle pathogenesis explain the particle heterogeneity that hampers the diagnostic identification of particles. For this reason, a histopathological particle algorithm has been developed that, with minimal methodical complexity, offers a guide to particle identification. Light microscopic–morphological as well as enzyme–histochemical characteristics and polarization–optical properties have been defined. Particles are characterized in accordance with a dichotomous principle. Based on these criteria, identification and validation of the particles was carried out in 105 joint endoprosthesis pathological cases. A particle score is proposed that summarizes the most important information for the orthopedist.