Background: 

The preoperative diagnosis of periprosthetic joint infection (PJI) depends on a series of blood biomarkers. Previous studies have shown that CD64 expression on blood neutrophils and monocytes has a good diagnostic efficacy for diagnosing systemic and local infections. The purpose of the present study was to investigate the role of blood CD64 in the diagnosis of PJI.

Methods: 

On the basis of estimations made before the study was performed, 62 patients were recruited for joint revision surgery following the failure of primary hip or knee replacement. Venous blood was obtained within 24 hours after patient admission, and flow cytometry was performed to evaluate the CD64 expression of 3 groups of white blood cells (WBCs). CD64 expression was measured as CD64 mean fluorescence intensity (CD64MFI). The neutrophil CD64 index (nCD64 index; neutrophil CD64MFI [nCD64MFI]/lymphocyte CD64MFI [lCD64MFI]) and monocyte CD64 index (mCD64 index; monocyte CD64MFI [mCD64MFI]/lCD64MFI) were then calculated. The C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) at admission, synovial fluid indicators, leukocyte esterase test results, intraoperative histological results, and tissue or synovial fluid culture results were recorded. According to the modified Musculoskeletal Infection Society (MSIS) criteria, patients were divided into the PJI group and the non-PJI group. These blood indicators were then analyzed for the diagnosis of PJI.

Results: 

The PJI group included 18 patients, and the non-PJI group included 44 patients. The diagnostic value of the area under the receiver operating characteristic curve (AUC) was low for lCD64MFI, the nCD64 index, and the mCD64 index. The diagnostic value for nCD64MFI was moderate, with an AUC of 0.735 (95% confidence interval [CI], 0.595 to 0.874; p = 0.004). The diagnostic value for mCD64MFI was high, with an AUC of 0.898 (95% CI, 0.821 to 0.975; p < 0.001). The cutoff value for mCD64MFI was 28,968, with a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 1, 0.75, 0.62, and 1, respectively. This result was confirmed by internal validation with a different antibody.

Conclusions: 

Flow cytometry can be used for patient screening before revision surgery, and blood mCD64MFI is a promising indicator for PJI.

Level of Evidence: 

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

中文翻译：

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评估血液单核细胞上CD64表达的临床先导研究，作为骨膜周围关节感染的指标。

背景： 

假体周围关节感染（PJI）的术前诊断取决于一系列血液生物标志物。先前的研究表明，血液中性粒细胞和单核细胞上CD64的表达对于诊断全身和局部感染具有良好的诊断功效。本研究的目的是调查血液CD64在PJI诊断中的作用。

方法： 

根据研究进行前的估计，招募了62例因初次髋关节或膝关节置换失败而进行关节翻修手术的患者。患者入院后24小时内获得静脉血，并进行流式细胞术以评估3组白细胞（WBC）的CD64表达。测量CD64表达，作为CD64平均荧光强度（CD64MFI）。然后计算中性粒细胞CD64指数（nCD64指数；中性粒细胞CD64MFI [nCD64MFI] /淋巴细胞CD64MFI [lCD64MFI]）和单核细胞CD64指数（mCD64指数；单核细胞CD64MFI [mCD64MFI] / lCD64MFI）。入院时的C反应蛋白（CRP）和红细胞沉降率（ESR），滑液指标，白细胞酯酶测试结果，术中组织学结果，并记录组织或滑液的培养结果。根据修改后的肌肉骨骼感染学会（MSIS）标准，将患者分为PJI组和非PJI组。然后对这些血液指标进行分析，以诊断PJI。

结果： 

PJI组包括18例患者，非PJI组包括44例患者。对于lCD64MFI，nCD64指数和mCD64指数，接收器工作特性曲线（AUC）下区域的诊断值较低。nCD64MFI的诊断值为中等，AUC为0.735（95％置信区间[CI]为0.595至0.874； p = 0.004）。mCD64MFI的诊断价值很高，AUC为0.898（95％CI，0.821至0.975； p <0.001）。mCD64MFI的临界值为28,968，灵敏度，特异性，阳性预测值（PPV）和阴性预测值（NPV）分别为1、0.75、0.62和1。通过使用另一种抗体进行内部验证证实了该结果。

结论： 

流式细胞术可用于翻修手术前的患者筛查，血液mCD64MFI是PJI的有前途的指标。

证据级别： 

诊断级别II。有关证据水平的完整说明，请参见《作者说明》。