Department of Orthopedics and Tumour Orthopedics, Muenster University Hospital, Albert-Schweitzer-Campus 1, 48149, Muenster, Germany.
J Orthop Traumatol. 2022 Nov 19;23(1):52. doi: 10.1186/s10195-022-00672-5.
Synovial fluid markers (synovial leukocyte count and differential) have been shown to be most accurate in diagnosing prosthetic joint infection (PJI). An inverse correlation for synovial leukocyte count and synovial pH is known assuming that leukocyte metabolism causes synovial fluid acidosis. This study's purpose is to analyze the use of synovial pH as a potential diagnostic marker for PJI.
92 patients who presented with painful total joint arthroplasty (TJA) of the hip (THA; n = 25) or knee (TKA, n = 67) were prospectively investigated. In our cohort 33% (30/92) had PJI and 67% (62/92) were diagnosed non-infected based on the modified Musculoskeletal Infection Society (MSIS) criteria of 2018. Receiver operating curves and the Youden's index were used to define an ideal cut-off value for synovial pH and the sensitivity and specificity were calculated using cross-tables. Additionally, the sensitivity and specificity were calculated for synovial white blood cell (WBC) count (cut-off > 3000 leukocytes) and percentage of neutrophils (PMN%, cut-off > 80%).
The median synovial pH level was significantly lower in the group with chronic PJI compared to implants with aseptic failure (7.09 vs. 7.27; p < 0.001). The calculated optimal cut-off value was 7.11 (AUC 0.771) with a sensitivity of 53% and specificity of 89%. However, the sensitivity and specificity of synovial WBC count were 90% and 88% and for synovial PMN% 73% and 98%, respectively.
Synovial pH may be a useful adjunct parameter in the diagnosis of chronic PJI after hip or knee arthroplasty, but showed low sensitivity in this preliminary cohort. Future studies with larger numbers are needed.
2a, diagnostic study. Trial registration German Clinical Trials Register (Registration number: DRKS00021038).
滑膜液标志物（滑膜白细胞计数和分类）在诊断人工关节感染（PJI）方面最为准确。已知滑膜白细胞代谢会导致滑膜液酸中毒，因此滑膜白细胞计数与滑膜 pH 值呈负相关。本研究旨在分析滑膜 pH 值作为 PJI 潜在诊断标志物的用途。
前瞻性调查了 92 例因髋关节（THA；n=25）或膝关节（TKA，n=67）全膝关节置换术（TJA）出现疼痛的患者。在我们的队列中，33%（30/92）患有 PJI，67%（62/92）根据 2018 年改良肌肉骨骼感染协会（MSIS）标准诊断为非感染。使用接收器工作曲线和 Youden 指数来定义滑膜 pH 值的理想截断值，并使用交叉表计算敏感性和特异性。此外，还计算了滑膜白细胞计数（截断值>3000 个白细胞）和中性粒细胞百分比（PMN%，截断值>80%）的敏感性和特异性。
与无菌性失败的植入物相比，慢性 PJI 组的滑膜 pH 值中位数明显较低（7.09 与 7.27；p<0.001）。计算出的最佳截断值为 7.11（AUC 0.771），敏感性为 53%，特异性为 89%。然而，滑膜白细胞计数的敏感性和特异性分别为 90%和 88%，而滑膜 PMN%的敏感性和特异性分别为 73%和 98%。
滑膜 pH 值可能是髋关节或膝关节置换术后诊断慢性 PJI 的有用辅助参数，但在本初步队列中敏感性较低。需要进行更大规模的未来研究。
2a 级，诊断研究。试验注册德国临床试验注册处（注册号：DRKS00021038）。
