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Aim-To characterise the number and nature of the inflammatory cells seen in cases of septic or aseptic loosening of hip arthroplasty, and to establish reliable histological criteria to distinguish between these two conditions. Methods-Histological examination of paraYn sections of periprosthetic tissues (pseudocapsule, femoral and acetabular pseudomembranes) of 523 cases of aseptic loosening and 79 cases of microbiology culture proven septic loosening. The cellular composition of the inflammatory cell infiltrate was determined semiquantitatively. Results-The finding of a 2+ or greater neutrophil polymorph infiltrate (one or more cells per high power field (×400) on average after examination of 10 fields) in arthroplasty tissues correlated strongly with the microbiological diagnosis of septic loosening: diagnostic sensitivity 100%, specificity 97%, accuracy 99%, positive predictive value 92%, negative predictive value 100%. The finding of a 3+ neutrophil polymorph infiltrate (five or more cells on average per high power field) had a diagnostic sensitivity of 72%, specificity 100%, accuracy 98%, positive predictive value 100%, and negative predictive value 97%. In some cases of septic loosening the finding of a heavy lymphocytic and plasma cell infiltrate was of low diagnostic sensitivity. A neutrophil polymorph infiltrate (generally less than one cell per 10 high power fields) was also seen in cases of aseptic loosening. Conclusions-The presence of 2+ or more (more than one neutrophil polymorph per high power field (×400) on average after examination of at least 10 high power fields) in periprosthetic tissues provides the most sensitive and accurate histopathological criterion for distinguishing between septic and aseptic loosening of hip arthroplasty. (J Clin Pathol 1999;52:118-123)

We assessed the efficacy of intraoperative frozen-section histology in detecting infection in failed arthroplasties in 106 hips and knees. We found inflammatory changes consistent with infection (an average of one or more neutrophil polymorphs or plasma cells per high-power field in several samples) in 18 cases; there was a significant growth on bacterial culture in 20 cases. Compared with the bacterial cultures, the frozen sections provided two false-negative results and three false-positive results (sensitivity, 90%; specificity, 96%; and accuracy, 95%). The positive predictive value was 88%, the negative value, 98%. These results support the inclusion of intra-operative frozen-section histology in any protocol for revision arthroplasty for loose components.

B-lineage cells reconcile the competing needs of proliferation and genome stability.

LDR exposure enhanced the function of macrophages and responses of CD8(+) T cells in C57BL/6 mice.

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An assessment of clinical and laboratory findings is generally required to distinguish between septic and aseptic loosening of a hip implant. In order to evaluate the diagnostic utility of histological and microbiological investigative techniques to differentiate between these two conditions, we analysed their results in 617 patients with hip implant loosening. Histology and microbiology study confirmed the clinical diagnosis of septic loosening in approximately 98% and 89%. respectively. The clinical diagnosis of aseptic loosening was confirmed by histology in 99% of cases. In all but 2 of 81 cases of septic loosening, in which an organism was isolated on microbiological culture, the histological diagnosis of septic loosening was made on the basis of the degree of the acute inflammatory infiltrate (i.e. the presence of 1 or more neutrophil polymorphs per high power field (x 400) on average after examination of at least 10 high power fields) in periprosthetic tissues. In 10 patients for whom there was a strong clinical suspicion of septic loosening but no organisms were isolated on microbiological culture, the histological findings, using the above criteria, were in keeping with the clinical diagnosis of septic loosening. As almost 11% of cases of septic loosening would not have been diagnosed by microbiological investigation alone, our findings indicate that histological examination of periprosthetic tissues should form part of the investigative protocol to distinguish between aseptic and septic loosening.