Department of Orthopaedic Surgery, Keck School of Medicine of USC, Los Angeles, California, USA.
Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois, USA.
Bone Joint J. 2020 Jun;102-B(6_Supple_A):138-144. doi: 10.1302/0301-620X.102B6.BJJ-2019-1679.R1.
In patients with a "dry" aspiration during the investigation of prosthetic joint infection (PJI), saline lavage is commonly used to obtain a sample for analysis. The aim of this study was to investigate prospectively the impact of saline lavage on synovial fluid analysis in revision arthroplasty.
Patients undergoing revision hip (THA) or knee arthroplasty (TKA) for any septic or aseptic indication were enrolled. Intraoperatively, prior to arthrotomy, the maximum amount of fluid possible was aspirated to simulate a dry tap (pre-lavage) followed by the injection with 20 ml of normal saline and re-aspiration (post-lavage). Pre- and post-lavage synovial white blood cell (WBC) count, percent polymorphonuclear cells (%PMN), and cultures were compared.
A total of 78 patients had data available for analysis; 17 underwent revision THA and 61 underwent revision TKA. A total of 16 patients met modified Musculoskeletal Infection Society (MSIS) criteria for PJI. Pre- and post-lavage %PMNs were similar in septic patients (87% vs 85%) and aseptic patients (35% vs 39%). Pre- and post-lavage synovial fluid WBC count were far more disparate in septic (53,553 vs 8,275 WBCs) and aseptic (1,103 vs 268 WBCs) cohorts. At a cutoff of 80% PMN, the post-lavage aspirate had a sensitivity of 75% and specificity of 95%. At a cutoff of 3,000 WBCs, the post-lavage aspirate had a sensitivity of 63% and specificity of 98%. As the post-lavage synovial WBC count increased, the difference between pre- and post-lavage %PMN decreased (mean difference of 5% PMN in WBC < 3,000 vs mean difference 2% PMN in WBC > 3,000, p = 0.013). Of ten positive pre-lavage fluid cultures, only six remained positive post-lavage.
While saline lavage aspiration significantly lowered the synovial WBC count, the %PMN remained similar, particularly at WBC counts of > 3,000. These findings suggest that in patients with a dry-tap, the %PMN of a saline lavage aspiration has reasonable sensitivity (75%) for the detection of PJI. Cite this article: 2020;102-B(6 Supple A):138-144.
在疑似人工关节感染（PJI）患者中，“干抽”时通常会使用生理盐水灌洗来获取分析样本。本研究旨在前瞻性地研究在翻修关节置换术中生理盐水灌洗对关节滑液分析的影响。
纳入因任何感染或非感染原因接受翻修髋关节（THA）或膝关节（TKA）置换术的患者。术中，在切开关节前，尽可能抽吸最大量的关节液以模拟“干抽”（预灌洗），随后注入 20ml 生理盐水并再次抽吸（后灌洗）。比较预灌洗和后灌洗的关节滑液白细胞（WBC）计数、中性粒细胞百分比（%PMN）和培养物。
共 78 例患者的数据可用于分析；17 例接受了 THA 翻修，61 例接受了 TKA 翻修。共有 16 例患者符合改良肌肉骨骼感染协会（MSIS）的 PJI 标准。在感染组（87% vs 85%）和非感染组（35% vs 39%）中，预灌洗和后灌洗的 %PMN 相似。在感染组（53553 vs 8275 个 WBC）和非感染组（1103 vs 268 个 WBC）中，预灌洗和后灌洗的关节滑液 WBC 计数差异很大。PMN 后灌洗的截断值为 80%时，其敏感性为 75%，特异性为 95%。PMN 后灌洗的截断值为 3000 个 WBC 时，敏感性为 63%，特异性为 98%。随着后灌洗关节滑液 WBC 计数的增加，预灌洗和后灌洗 %PMN 之间的差异减小（WBC < 3000 时PMN 差异为 5%，WBC > 3000 时PMN 差异为 2%，p = 0.013）。在 10 例预灌洗时阳性的滑液培养中，只有 6 例在后灌洗时仍为阳性。
虽然生理盐水灌洗抽吸显著降低了关节滑液 WBC 计数，但 %PMN 仍保持相似，尤其是在 WBC 计数> 3000 时。这些发现表明，在干抽的患者中，PMN 后灌洗抽吸对 PJI 的检测具有合理的敏感性（75%）。
