人工关节置换术后外周血白细胞计数变化趋势的临床意义

Clinical significance of changes in peripheral white blood cell count after total joint arthroplasty

目的通过观察髋、膝关节置换术(TJA)后外周血白细胞计数(WBC)的变化趋势,探讨TJA后早期WBC增高是否需要进一步的检查以排除感染。方法将2019年6月至2020年6月在新疆医科大学第一附属医院关节外科行初次髋、膝TJA后1个月内未出现假体周围感染(PJI)的294例患者设为未感染组,2012年5月至2020年6月行初次髋、膝TJA后1个月内出现PJI的31例患者设为感染组,回顾性分析这325例患者的临床资料。分别于术前及术后1~5 d检测并记录外周血WBC,比较各时间点差异,采用多重线性回归分析筛选出与术后早期WBC增高相关的因素,利用受试者工作特征(ROC)曲线评价WBC对早期PJI的预测价值。结果未感染组患者的外周血WBC水平呈先升高后下降的趋势,且在术后2 d达到高峰,术后2 d较术前增加(8.08×10^(9)/L±2.33×10^(9)/L),随后开始下降,术后5 d降至略高于术前水平。术后前2 d WBC变化范围为6.24×10^(9)/L~26.32×10^(9)/L。术后前5 d WBC增高的发生率为95.6%(281/294)。与术后WBC增高相关的因素包括术前WBC和双侧手术:术前WBC每增加1.00×10^(9)/L,术后WBC平均增加0.98×10^(9)/L[β=0.984,95%可信区间(95%CI):0.821~1.148,P<0.001],行双侧手术患者的术后WBC较单侧平均增加1.03×10^(9)/L(β=1.026,95%CI:0.565~1.486,P<0.001)。WBC绝对差值(术后最大WBC值与基线的绝对差值)预测早期PJI的曲线下面积为0.655(95%CI:0.546~0.764,P<0.05),分析提供的阈值为7.96×10^(9)/L,敏感性为57.5%,特异性为74.2%。结论TJA后WBC增高是一种常见现象,代表了对手术的正常生理反应。术前WBC是术后WBC增高的预测指标。在没有异常临床症状和体征的情况下,若术后WBC未偏离其变化范围及趋势,则不需要进一步检查是否存在感染。

Objective To study whether early leukocytosis after total joint arthroplasty(TJA)requires further workup to exclude infection by observing changes in peripheral blood white blood cell(WBC)count after TJA.Methods This study included the 294 patients(infection-free group)who had undergone primary hip or knee TJA from June 2019 to June 2020 but reported no periprosthetic joint infection(PJI)within one month after surgery and the 31 patients(infection group)who had undergone the same TJA but reported infection within one month after surgery from May 2012 to June 2020 at Department of Joint Surgery,The First Affiliated Hospital to Xinjiang Medical University.Peripheral blood WBC counts were measured and recorded before surgery and 1 to 5 days after surgery.Differences were compared between time points and multiple linear regression analysis was used to screen the factors associated with early postoperative leukocytosis.The receiver operating characteristic(ROC)curve was used to evaluate the predictive value of WBC for early PJI.Results The peripheral WBC level in the infection-free group showed a trend of increasing at first and then decreasing.It reached the peak on day 2 after surgery,increasing by 8.08×10^(9)/L±2.33×10^(9)/L compared to pre-surgery,and then began to decrease to a level slightly higher than the preoperative value on day 5 after surgery.The changes in WBC count in the first 2 days after surgery ranged from 6.24×10^(9)/L to 26.32×10^(9)/L.The incidence of leukocytosis in the first 5 days after surgery was 95.6%(281/294).The factors associated with postoperative leukocytosis included preoperative WBC count and bilateral surgery.For every increase of 1.00×10^(9)/L in preoperative WBC count,the postoperative WBC value increased by an average of 0.98×10^(9)/L[β=0.984,95%confidence interval(95%CI):0.821-1.148,P<0.001].The postoperative WBC count in the patients undergoing bilateral surgery increased by an average of 1.03×10^(9)/L compared with that in the patients undergoing unilateral surgery(β=1.026,95%CI:0.565-1.486,P<0.001).The area under the curve(AUC)for prediction of early PJI by absolute WBC count difference(the absolute difference between the maximum postoperative WBC value and the baseline)was 0.655(95%CI:0.546-0.764,P<0.05),providing a threshold of 7.96×10^(9)/L,a sensitivity of 57.5%and a specificity of 74.2%.Conclusions Leukocytosis is a common phenomenon after TJA,indicating a normal physiological response to surgery.The preoperative WBC count is a predictor for postoperative leukocytosis.In the absence of abnormal clinical symptoms or signs,there is no need for further workup to check infection if the postoperative WBC does not deviate from its changing range and trend.