THE ROLE OF INTRAOPERATIVE FROZEN-SECTIONS IN REVISION TOTAL JOINT ARTHROPLASTY

We performed a retrospective analysis of thirty-three consecutive tota l hip and knee (twenty-three hip and ten knee) revision arthroplasties during which intraoperative frozen sections were analyzed. Data for t he study were collected by means of a review of the charts, radiograph ic analysis, and evaluation of both frozen and permanent histological sections. The frozen sections, of periprosthetic tissue at the bone-ce ment interface or the pseudocapsule, were considered positive for acti ve infection if there were more than five polymorphonuclear leukocytes per high-power field in at least five distinct microscopic fields. Al l patients were available for follow-up, at an average of thirty-six m onths (range, seventeen to seventy-nine months) after the initial revi sion operation. The frozen sections from ten patients were positive fo r infection, and those from twenty-three patients were negative. Compa rison of the results of the analyses of the frozen sections (both posi tive and negative) with those of the analyses of the permanent histolo gical sections of similar tissue showed a correlation of 100 per cent (sensitivity, 1.00; specificity, 1.00; and accuracy, 1.00). Nine patie nts had positive intraoperative cultures, and all of them had positive frozen sections (sensitivity, 1.00). Of the twenty-four patients who had negative intraoperative cultures, twenty-three had negative frozen sections (specificity, 0.96). Of the nine patients who had positive i ntraoperative cultures, only two were found to have infection on intra operative gram-staining. The surgeon's operative assessment regarding the presence of infection, compared,vith the final pathological diagno sis, demonstrated a sensitivity of 0.70, a specificity of 0.87, and an accuracy of 0.82. All ten patients who had positive frozen sections w ere managed with excision arthroplasty; six of them subsequently had r eimplantation, and the excision was the definitive procedure in the re maining four. One patient who had had a delayed reimplantation had wit h an arthrodesis of the knee. In the group that had negative frozen se ctions, eighteen patients had a primary exchange revision arthroplasty and five had a delayed reimplantation. At the time of follow-up, one patient who had had a delayed reimplantation had radiographic loosenin g of the femoral component and was asymptomatic. One patient who had h ad a primary exchange arthroplasty was managed,vith a second revision because of aseptic loosening. There was no clinical recurrence of infe ction in any patient. The data indicate that analysis of frozen sectio ns of periprosthetic tissue is a reliable predictor of the presence of active infection during revision joint arthroplasty. We recommend its use to differentiate aseptic from septic loosening.