Fuchs Michael, Kirchhoff Felix, Reichel Heiko, Perka Carsten, Faschingbauer Martin, Gwinner Clemens
RKU Department of Orthopaedic Surgery, University Ulm Medical Centre, Ulm, Baden-Württemberg, Germany.
Department of Orthopaedic Surgery, Charite Universitatsmedizin Berlin, Berlin, Berlin, Germany.
Bone Jt Open. 2021 Aug;2(8):566-572. doi: 10.1302/2633-1462.28.BJO-2021-0109.
Current guidelines consider analyses of joint aspirates, including leucocyte cell count (LC) and polymorphonuclear percentage (PMN%) as a diagnostic mainstay of periprosthetic joint infection (PJI). It is unclear if these parameters are subject to a certain degree of variability over time. Therefore, the aim of this study was to evaluate the variation of LC and PMN% in patients with aseptic revision total knee arthroplasty (TKA).
We conducted a prospective, double-centre study of 40 patients with 40 knee joints. Patients underwent joint aspiration at two different time points with a maximum period of 120 days in between these interventions and without any events such as other joint aspirations or surgeries. The main indications for TKA revision surgery were aseptic implant loosening (n = 24) and joint instability (n = 11).
Overall, 80 synovial fluid samples of 40 patients were analyzed. The average time period between the joint aspirations was 50 days (SD 32). There was a significantly higher percentage change in LC when compared to PMN% (44.1% (SD 28.6%) vs 27.3% (SD 23.7%); p = 0.003). When applying standard definition criteria, LC counts were found to skip back and forth between the two time points with exceeding the thresholds in up to 20% of cases, which was significantly more compared to PMN% for the European Bone and Joint Infection Society (EBJIS) criteria (p = 0.001), as well as for Musculoskeletal Infection Society (MSIS) (p = 0.029).
LC and PMN% are subject to considerable variation. According to its higher interindividual variance, LC evaluation might contribute to false-positive or false-negative results in PJI assessment. Single LC testing prior to TKA revision surgery seems to be insufficient to exclude PJI. On the basis of the obtained results, PMN% analyses overrule LC measurements with regard to a conclusive diagnostic algorithm. Cite this article: 2021;2(8):566-572.
当前指南将关节穿刺液分析，包括白细胞计数（LC）和多形核细胞百分比（PMN%）视为假体周围关节感染（PJI）的主要诊断依据。尚不清楚这些参数是否会随时间发生一定程度的变化。因此，本研究的目的是评估无菌性翻修全膝关节置换术（TKA）患者的LC和PMN%的变化情况。
我们对40例患者的40个膝关节进行了一项前瞻性、双中心研究。患者在两个不同时间点进行关节穿刺，两次干预之间的最长间隔时间为120天，且在此期间没有发生其他关节穿刺或手术等任何事件。TKA翻修手术的主要指征为无菌性植入物松动（n = 24）和关节不稳定（n = 11）。
总体而言，对40例患者的80份滑液样本进行了分析。两次关节穿刺之间的平均时间间隔为50天（标准差32）。与PMN%相比，LC的百分比变化明显更高（44.1%（标准差28.6%）对27.3%（标准差23.7%）；p = 0.003）。应用标准定义标准时，发现LC计数在两个时间点之间来回跳跃，超过阈值的情况高达20%，与欧洲骨与关节感染学会（EBJIS）标准下的PMN%相比显著更多（p = 0.001），与肌肉骨骼感染学会（MSIS）标准下的PMN%相比也显著更多（p = 0.029）。
LC和PMN%存在相当大的变化。根据其较高的个体间差异，LC评估可能会在PJI评估中导致假阳性或假阴性结果。TKA翻修手术前单次LC检测似乎不足以排除PJI。基于所获得的结果，就确定性诊断算法而言，PMN%分析比LC测量更具优势。引用本文：2021；2(8):566 - 572。
