Neutrophils in frozen section and type of microorganism isolated at the time of resection arthroplasty for the treatment of infection

The histology of periprosthetic tissue is a gold standard for the diagnosis of periprosthetic joint infection. However, the specificity and sensitivity of histology has never been 100%. In the present study we hypothesized that the type of microorganism could be related to the effectiveness of histology in the detection of infection. Frozen sections and cultures from periprosthetic tissue of 38 revision arthroplasties taken at the time of resection arthroplasty for the treatment of infection were retrospectively reviewed. Frozen sections were evaluated following Feldman's criteria. A culture was considered positive when the same microorganism was isolated in at least two samples or when pus was present around the prosthesis. The literature providing information on histology and microbiology of arthroplasty-associated infection was reviewed. Coagulase-negative staphylococcus (CNS) was the etiology in 13 cases, Gram-negative bacilli in 8, Staphylococcus aureus in 7, Candida sp in 2, Peptococcus sp in 2, Enterococcus sp in 1 and S. pneumoniae in 1. No microorganism was isolated in four cases. Almost all the frozen sections in the 38 cases were positive except in 2 of the 13 that were caused by CNS (15.3%). The articles reviewed supported our findings. Frozen section is a useful test to intraoperatively confirm an infection when preoperative septic loosening is suspected. However, histology has false-negative results when the infection is due to low-virulence microorganisms.