BACKGROUND The leukocyte esterase (LE) strip is considered as a helpful method to detect infection, which might be influenced by other inflammatory diseases. This study aims to explore whether the centrifugation of synovial fluid could influence the positive result of LE strip caused by inflammatory arthritis during the diagnosis of periprosthetic joint infection (PJI). METHODS From March 2016 to December 2018, 64 patients who were diagnosed as PJI or aseptic arthritis and another 20 patients with inflammatory arthritis were enrolled in our study. After synovial fluid samples were obtained, the LE strip test was performed with and without centrifugation. Then clinicians read the color changes 3 min after the samples were dropped and classify the results based on the instruction of strip. The differences between septic and aseptic arthritis patients and septic and inflammatory arthritis patients were analyzed. RESULTS Among the included 21 PJI samples, 19 of them showed positive results (++) of LE strip before centrifugation. After centrifugation, two samples changed from two-positive (++) to one-positive (+), which is also considered as positive. Before centrifugation, 29 of the LE strip tests in the aseptic arthritis group (43 samples included) were ++ or +. After centrifugation, 16 of the samples yielded negative results. Among 20 samples with inflammatory arthritis, LE strip of 18 samples were positive (++ or +) before centrifugation, among which only 3 samples remained as positive after centrifugation. CONCLUSION LE strip test results could be influenced by inflammatory arthritis during the diagnosis of PJI. Centrifugation should be performed for LE strip tests to determine whether the result is a true positive or a false positive influenced by inflammatory arthritis.

中文翻译：

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炎性关节炎对白细胞酯酶剥离的影响导致假体周围关节感染的诊断。

背景技术白细胞酯酶（LE）条被认为是检测感染的有用方法，感染可能受到其他炎症性疾病的影响。本研究旨在探讨在关节假体周围感染（PJI）的诊断过程中，滑液的离心分离是否会影响由炎症性关节炎引起的LE条带的阳性结果。方法从2016年3月至2018年12月，我们纳入了64例被诊断为PJI或无菌性关节炎的患者和另外20例炎性关节炎的患者。获得滑液样本后，在有和没有离心的情况下进行LE剥离测试。然后，临床医生在滴下样品3分钟后读取颜色变化，并根据试纸的说明对结果进行分类。分析了化脓性和无菌性关节炎患者与化脓性和炎性关节炎患者之间的差异。结果在21个PJI样本中，有19个在离心前显示LE条带阳性（++）。离心后，两个样品从二阳性（++）变为一阳性（+），这也被视为阳性。离心之前，无菌关节炎组中的29条LE试纸（包括43个样品）为++或+。离心后，有16个样品产生阴性结果。在20例炎性关节炎样本中，离心前的LE条带18个样本为阳性（++或+），其中只有3个样本在离心后保持阳性。结论LE试纸条检测结果可能受PJI诊断过程中炎性关节炎的影响。