Fig. 3

Prosthetic debris accumulation in synovial membrane-like tissues. a Histological grading for accumulation of polymeric particles (PP) in aseptic interface membranes. b PP surrounded by macrophages (brown cells). c Same section of (H) under polarized light showing birefringent PP. d Histological grading for deposition of ZrO₂ particles in synovial membrane-like interface tissues. e H&E image of aseptic interface membrane with intense deposition of ZrO₂ particles (black arrows) using conventional light microscopy. f Same tissue region observed using Ph3 filter with white and bright particles corresponding to ZrO₂ debris (white arrows). g Macrophages (brown cells) phagocytizing ZrO₂ debris (black arrows). h SEM image of synovial membrane-like interface tissues containing clusters (Z1) and sole (Z2) ZrO₂ nanoparticles. i EDS analysis confirming the elemental composition of ZrO₂ nanoparticles. j Histological grading for entrapment of metallic particles in tissues. k Macrophages (brown cells, CD68 + cells) with phagocytized metallic particles. l Metallic particles co-localized with macrophages and high deposition of collagen (blue stain). m Necrosis (N) in regions of aseptic interface membranes with massive accumulation of metallic particles. n Tissue from an AL patient with metallosis showing metallic particles and erythrocytes. o Same tissue section shwoing bright metallic particles and erythrocytes but exhibited under Ph3 filter violet and red colors, respectively. H&E staining (e, m, n), polarized light (c), Ph3 filter (f, o), Masson’s trichrome (l) immunohistochemistry (b, g, k), SEM imaging (h) and EDS spectra (i). Scale bars correspond to 500 μm (e, m), 50 μm (b, k, l) and 20 μm (g, n, o). Semi-quantitative histological evaluation was performed in tissues retrieved from 19/20 AL patients