Twenty-three neutrophil granulocytes in 10 high-power fields is the best histopathological threshold to differentiate between aseptic and septic endoprosthesis loosening
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Updated: Jun 21, 2026
Morphological and Compositional Analysis of Neutrophil Extracellular Traps Induced by Microbial and Chemical Stimuli
Published on: November 4, 2022
Lars Morawietz1, Obbe Tiddens, Michael Mueller
1Institute of Pathology, Charité University Hospital, Berlin, Germany. lars.morawietz@charite.de
Aims:
The histopathological diagnosis of infection in periprosthetic tissue from loose total joint endoprosthesis has been the subject of controversy. The aim was to define a histological criterion that would best differentiate between aseptic and septic endoprosthesis loosening.
Methods And Results:
Neutrophilic granulocytes (NG) were enumerated histopathologically in 147 periprosthetic membranes obtained from aseptic and septic revision surgery, using periodic acid-Schiff (PAS) stains and CD15 immunohistochemistry. Cell numbers were correlated with the results of microbiological culture and the clinical diagnoses. Using receiver-operating characteristics, an optimized threshold was found at 23 NG in 10 high-power fields (HPF). Using this threshold, histopathological examination had a sensitivity of 73% and specificity of 95% when compared with microbiological diagnosis (area under the curve 0.881), and a sensitivity of 77% and specificity of 97% when compared with clinical diagnosis (area under the curve 0.891).
Conclusions:
We therefore recommend a counting algorithm with a threshold of > or =23 NG in 10 HPF (visual field diameter 0.625 mm) for the histopathological diagnosis of septic endoprosthesis loosening. If the enumeration of NG is difficult in conventional haematoxylin and eosin-stained slides, CD15 immunohistochemistry should be performed, whereas the PAS stain has not proven to be helpful.
