Wouthuyzen-Bakker M, Ploegmakers J J W, Kampinga G A, Wagenmakers-Huizenga L, Jutte P C, Muller Kobold A C
University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9700 RB, Groningen, The Netherlands.
Bone Joint J. 2017 May;99-B(5):660-665. doi: 10.1302/0301-620X.99B5.BJJ-2016-0913.R2.
Recently, several synovial biomarkers have been introduced into the algorithm for the diagnosis of a prosthetic joint infection (PJI). Alpha defensin is a promising biomarker, with a high sensitivity and specificity, but it is expensive. Calprotectin is a protein that is present in the cytoplasm of neutrophils, is released upon neutrophil activation and exhibits anti-microbial activity. Our aim, in this study, was to determine the diagnostic potential of synovial calprotectin in the diagnosis of a PJI.
In this pilot study, we prospectively collected synovial fluid from the hip, knee, shoulder and elbow of 19 patients with a proven PJI and from a control group of 42 patients who underwent revision surgery without a PJI. PJI was diagnosed according to the current diagnostic criteria of the Musculoskeletal Infection Society. Synovial fluid was centrifuged and the supernatant was used to measure the level of calprotectin after applying a lateral flow immunoassay.
The median synovial calprotectin level was 991 mg/L (interquartile range (IQR) 154 to 1787) in those with a PJI and 11 mg/L (IQR 3 to 29) in the control group (p < 0.0001). Using a cut-off value of 50 mg/L, this level showed an excellent diagnostic accuracy, with an area under the curve of 0.94. The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) was 89%, 90%, 81% and 95% respectively. The NPV was 97% in the nine patients with a chronic PJI.
Synovial calprotectin may be a valuable biomarker in the diagnosis of a PJI, especially in the exclusion of an infection. With a lateral flow immunoassay, a relatively rapid quantitative diagnosis can be made. The measurement is cheap and is easy to use. Cite this article: 2017;99-B:660-5.
最近，几种滑膜生物标志物已被纳入人工关节感染（PJI）的诊断算法中。α防御素是一种很有前景的生物标志物，具有高敏感性和特异性，但成本高昂。钙卫蛋白是一种存在于中性粒细胞胞质中的蛋白质，在中性粒细胞激活时释放，并具有抗菌活性。本研究的目的是确定滑膜钙卫蛋白在PJI诊断中的潜在诊断价值。
在这项前瞻性试点研究中，我们从19例已确诊PJI的患者的髋、膝、肩和肘关节中前瞻性收集滑液，并从42例接受翻修手术但无PJI的对照组患者中收集滑液。PJI根据肌肉骨骼感染学会的现行诊断标准进行诊断。滑液经离心处理，上清液用于通过侧向流动免疫测定法测量钙卫蛋白水平。
PJI患者的滑膜钙卫蛋白水平中位数为991mg/L（四分位间距（IQR）为154至1787），而对照组为11mg/L（IQR为3至29）（p<0.0001）。使用50mg/L的临界值，该水平显示出极佳的诊断准确性，曲线下面积为0.94。总体敏感性、特异性、阳性预测值（PPV）和阴性预测值（NPV）分别为89%、90%、81%和95%。9例慢性PJI患者的NPV为97%。
滑膜钙卫蛋白可能是PJI诊断中的一种有价值的生物标志物，尤其是在排除感染方面。通过侧向流动免疫测定法，可以进行相对快速的定量诊断。该测量成本低廉且易于使用。引用本文：2017；99-B：660-5。
