Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
Bone Joint J. 2021 Jun;103-B(6 Supple A):177-184. doi: 10.1302/0301-620X.103B6.BJJ-2020-2397.R1.
It remains difficult to diagnose early postoperative periprosthetic joint infection (PJI) following total knee arthroplasty (TKA). We aimed to validate the optimal cutoff values of ESR, CRP, and synovial fluid analysis for detecting early postoperative PJI in a large series of primary TKAs.
We retrospectively identified 27,066 primary TKAs performed between 2000 and 2019. Within 12 weeks, 169 patients (170 TKAs) had an aspiration. The patients were divided into two groups: those evaluated ≤ six weeks, or between six and 12 weeks postoperatively. The 2011 Musculoskeletal Infection Society (MSIS) criteria for PJI diagnosis in 22 TKAs. The mean follow-up was five years (two months to 17 years). The results were compared using medians and Mann-Whitney U tests and thresholds were analyzed using receiver operator characteristic curves.
Within six weeks, the median CRP (101 mg/l vs 35 mg/l; p = 0.011), synovial WBCs (58,295 cells/μl vs 2,121 cells/μl; p ≤ 0.001), percentage of synovial neutrophils (91% vs 71% (p < 0.001), and absolute synovial neutrophil count (ANC) (50,748 cells/μl vs 1,386 cells/μl (p < 0.001) were significantly higher in infected TKAs. Between six and 12 weeks, the median CRP (85 mg/l vs 5 mg/l (p < 0.001)), ESR (33 mm/hr vs 14 mm/hr (p = 0.015)), synovial WBCs (62,247 cells/μl vs 620 cells/μl (p < 0.001)), percentage of synovial neutrophils (93% vs 54% (p < 0.001)), and ANC (55,911 cells/μl vs 326 cells/μl (p < 0.001)) were also significantly higher in infected TKAs. Optimal thresholds at ≤ six weeks were: CRP ≥ 82 mg/l (sensitivity 70%, specificity 77%), synovial WBCs ≥ 8,676 cells/μl (83%, 90%), percentage of synovial neutrophils ≥ 88% (67%, 78%), and ANC ≥ 8,346 cells/μl (83%, 91%). Between six and 12 weeks, thresholds were: CRP ≥ 34 mg/l (90%, 93%), synovial WBCs ≥ 1,983 cells/μl (80%, 85%), percentage of synovial neutrophils ≥ 76% (80%, 81%), and ANC ≥ 1,684 cells/μl (80%, 87%).
Early PJI after TKA should be suspected within six weeks if the CRP is ≥ 82 mg/l, synovial WBCs are ≥ 8,676 cells/μl, the percentage of synovial neutrophils is ≥ 88%, and/or the ANC is ≥ 8,346 cells/μl. Between six and 12 weeks, thresholds include a CRP of ≥ 34 mg/l, synovial WBC of ≥ 1,983 cells/μl, a percentage of synovial neutrophils of ≥ 76%, and/or an ANC of ≥ 1,684 cells/μl. Cite this article: 2021;103-B(6 Supple A):177-184.
全膝关节置换术后（TKA）早期发生假体周围关节感染（PJI）仍然难以诊断。我们旨在验证 ESR、CRP 和关节液分析的最佳截断值，以在大量初次 TKA 系列中检测早期术后 PJI。
我们回顾性地确定了 2000 年至 2019 年间进行的 27066 例初次 TKA。在 12 周内，有 169 例患者（170 例 TKA）进行了抽吸。患者分为两组：≤6 周和 6 至 12 周术后评估。22 例 TKA 采用 2011 年肌肉骨骼感染协会（MSIS）的 PJI 诊断标准。平均随访时间为 5 年（2 个月至 17 年）。使用中位数和曼-惠特尼 U 检验比较结果，并使用接收者操作特征曲线分析阈值。
在 6 周内，CRP（101mg/L 与 35mg/L；p=0.011）、关节液白细胞计数（58295 细胞/μl 与 2121 细胞/μl；p≤0.001）、关节液中性粒细胞百分比（91%与 71%（p<0.001）和绝对关节液中性粒细胞计数（ANC）（50748 细胞/μl 与 1386 细胞/μl（p<0.001）在感染 TKA 中显著更高。在 6 至 12 周之间，CRP（85mg/L 与 5mg/L（p<0.001））、ESR（33mm/hr 与 14mm/hr（p=0.015））、关节液白细胞计数（62247 细胞/μl 与 620 细胞/μl（p<0.001））、关节液中性粒细胞百分比（93%与 54%（p<0.001））和 ANC（55911 细胞/μl 与 326 细胞/μl（p<0.001））在感染 TKA 中也显著更高。≤6 周的最佳阈值为：CRP≥82mg/L（敏感性 70%，特异性 77%）、关节液白细胞计数≥8676 细胞/μl（83%，90%）、关节液中性粒细胞百分比≥88%（67%，78%）和 ANC≥8346 细胞/μl（83%，91%）。在 6 至 12 周之间，阈值为：CRP≥34mg/L（90%，93%）、关节液白细胞计数≥1983 细胞/μl（80%，85%）、关节液中性粒细胞百分比≥76%（80%，81%）和 ANC≥1684 细胞/μl（80%，87%）。
TKA 后早期 PJI 应在 6 周内怀疑，如果 CRP≥82mg/L、关节液白细胞计数≥8676 细胞/μl、关节液中性粒细胞百分比≥88%和/或 ANC≥8346 细胞/μl。在 6 至 12 周之间，阈值包括 CRP≥34mg/L、关节液白细胞计数≥1983 细胞/μl、关节液中性粒细胞百分比≥76%和/或 ANC≥1684 细胞/μl。
