Periprosthetic joint infections (PJI) are severe complications after total joint arthroplasty (TJA). Up to now, a gold standard in the diagnostics of PJI is missing. Small extracellular vesicles (sEVs) are secreted by all types of cells and play a key role in immune response in presence of infection (1). In this prospective study, the diagnostic accuracy of sEVs in the synovial fluid to detect PJI of knee, hip and shoulder joints was investigated. We hypothesized increased surface markers of sEVs in PJI compared to aseptic complications (e.g. implant loosening, stress shielding related pain). Synovial fluid from 48 patients with painful arthroplasty was examined. The distinction between aseptic and infectious cases was made on the basis of the 2018 Definition of Periprosthetic Hip and Knee Infection (2). 35 (72,9%) probands assigned to aseptic and 13 patients (27,1%) to PJI group. Immuno-fluorescence flow cytometry served to document the concentrations of CD9, CD63, CD66b, CD82 and HLA-DR on sEVs.Aim
Method
78 patients (41 male and 37 female) with a revision total knee or hip arthroplasty were enrolled in this prospective study to evaluate the role of new laboratory markers in the diagnostic of deep implant infection. The average age at the time of surgery was 64 years. Based on intraoperative cultures, 21 patients had a septic and 57 patients had an aseptic revision total joint arthroplasty. White blood cell counts, erythrocyte sedimentation rate, C-reactive protein levels, interleukin-6, procalcito-nin and TNF-alpha were measured in preoperative blood samples. Diagnostic cut of values were determined by Receiver Operating Characteristic curve analysis. If patients with rheumatoid arthritis and other concomitant infections are excluded the C-reactive protein (>
3.2md/dl) and interleukin 6 (>
12 pg/ml) have the highest sensitivity (0.95). Interleukin 6 is less specific than the C-reactive protein (0.87 versus 0.96). Combining C-reactive protein and interleukin identifies all patients with deep implant infection. Procalcitonin (>
0.3 ng/ml) and TNF-alpha (>
40 ng/ml) are very specific (0.98 versus 0.94)) but have a low sensitivity (0.33 versus 0.43). The combination of C-reactive protein and interleu-kin 6 is an excellent screening tests for deep implant infection. Highly specific marker like procalcitoninn as well as preoperative joint aspiration might be useful to identify patients with true positive CRP and/or interleu-kin 6 levels.
This prospective study evaluates the role of new laboratory markers in the diagnosis of deep implant infection in 78 patients (41 men and 37 women) with a revision total knee or hip replacement. The mean age at the time of operation was 64.0 years (19 to 90). Intra-operative cultures showed that 21 patients had a septic and 57 an aseptic total joint replacement. The white blood cell count, the erythrocyte sedimentation rate and levels of C-reactive protein, interleukin-6, procalcitonin and tumour necrosis factor (TNF)-α were measured in blood samples before operation. The diagnostic cut-off values were determined by Received Operating Characteristic curve analysis. C-reactive protein (>
3.2 md/dl) and interleukin-6 (>
12 pg/ml) have the highest sensitivity (0.95). Interleukin-6 is less specific than C-reactive protein (0.87 The combination of C-reactive protein and interleukin-6 measurement provide excellent screening tests for infection of a deep implant. A highly specific marker such as procalcitonin and pre-operative aspiration of the joint might be useful in identifying patients with true positive C-reactive protein and/or interleukin-6 levels.
