Elevated plasma D‐dimer concentration has higher efficacy for the diagnosis of periprosthetic joint infection of the knee than of the hip—A single‐center, retrospective study

The aim of this study is to evaluate the value of D‐dimers in the diagnosis of periprosthetic joint infection (PJI). The analysis was performed for revision total hip (rTHA) and revision total knee arthroplasty (rTKA) together and separately with two thresholds, one calculated by statistical methods and the second adopted from the ICM 2018 definition. The study group comprised 133 patients who underwent rTHA or rTKA: 68 patients diagnosed according to the ICM 2018 definition (PJI group) and 65 with aseptic implant loosening, instability, malposition, or implant failure with the exclusion of infection (aseptic revision total joint arthroplasty or arTJA group). Mean D‐dimer concentrations were 0.36 ± 0.25 μg/ml in the arTJA group and 0.87 ± 0.78 μg/ml in the PJI group (p < .001). For rTHA and rTKA together, the sensitivity and specificity of the evaluation were 75% and 73.8% according to the calculated cut‐off value (0.45 μg/ml), and 33.8% and 95.4% based on the ICM 2018 threshold (0.85 μg/ml). Separately, for rTHA, sensitivity and specificity were 62.5% and 62.1% for the calculated value (0.43 μg/ml) and 6.3% and 96.6% for the ICM 2018 threshold; for rTKA, sensitivity was 86.1% and specificity was 88.9% for the calculated threshold (0.48 μg/ml) and 58.3% and 94.4% for the ICM 2018 value. Our findings indicate that plasma D‐dimers have potential as markers of knee PJI, but moderate to low value for hip PJI.