Improved diagnosis of chronic hip and knee prosthetic joint infection using combined serum and synovial IL-6 tests

Abstract

Aims This study aimed to explore whether serum combined with synovial interleukin-6 (IL-6) measurement can improve the accuracy of prosthetic joint infection (PJI) diagnosis, and to establish the cut-off values of IL-6 in serum and synovial fluid in detecting chronic PJI. Methods Patients scheduled to have a revision surgery for indications of chronic infection of knee and hip arthroplasties or aseptic loosening of an implant were prospectively screened before being enrolled into this study. The Musculoskeletal Infection Society (MSIS) definition of PJI was used for the classification of cases as aseptic or infected. Serum CRP, ESR, IL-6, and percentage of polymorphonuclear neutrophils (PMN%) and IL-6 in synovial fluid were analyzed. Statistical tests were performed to compare these biomarkers in the two groups, and receiver operating characteristic (ROC) curves and area under the curve (AUC) were analyzed for each biomarker. Results A total of 93 patients were enrolled. There was no difference in demographic data between both groups. Synovial fluid IL-6, with a threshold of 1,855.36 pg/ml, demonstrated a mean sensitivity of 94.59% (95% confidence interval (CI) 81.8% to 99.3%) and a mean specificity of 92.86% (95% CI 82.7 to 98.0) for detecting chronic PJI. Then 6.7 pg/ml was determined to be the optimal threshold value of serum IL-6 for the diagnosis of chronic PJI, with a mean sensitivity of 97.30% (95% CI 85.8% to 99.9%) and a mean specificity of 76.79% (95% CI 63.6% to 87.0%). The combination of synovial IL-6 and serum IL-6 led to improved accuracy of 96.77% in diagnosing chronic PJI. Conclusion The present study identified that a combination of IL-6 in serum and synovial IL-6 has the potential for further improvement of the diagnosis of PJI. Cite this article: Bone Joint Res 2020;9(9):587–592.

Synovial Complement Factors in Patients with Periprosthetic Joint Infection after Undergoing Revision Arthroplasty of the Hip or Knee Joint

“…Sigmund, respectively Renz et al described the use of α-defensin in diagnosing a PJI with promising results [ 24 , 25 ]. While Grzelecki et al evaluated the utility of synovial Calprotectin, with a sensitivity of 93.3% and specificity of 87.5% [ 26 ], Quin et al analyzed the value of synovial and serum IL-6 with more than acceptable results (sensitivity: 94.6%/97.3%; specificity: 92.9%/76.8%) [ 27 ]. In comparison to these results several synovial biomarkers will outperform synovial complement factors in diagnosing a PJI.…”

Combined Serum and Synovial C-Reactive Protein Tests: An Economical and Efficient Adjunct to the Diagnosis of Chronic Prosthetic Joint Infection

“…The reasonable explanation is that CRP, a factor secreted by a variety of cells, increases to different degrees when the body is stimulated by in ammation [3,5]. Therefore, we investigated in ammatory markers of local synovial uid in joints with higher speci city [4]. Based on previous studies, detection time and economic bene ts, we focused on the value of synovial CRP in differentiating chronic PJI [13,14,23,24].…”

“…First of all, there is no clear consensus on the exact time of postoperative chronic PJI. Although the time of bio lm maturation and previous published studies were used as references in this study, cases of acute infection in included chronic PJI patients could not be completely excluded [4,28,29]. Second, this study involved a single center, and the sample size was relatively small, with only 39 cases in the chronic PJI group and 58 cases in the aseptic group.…”

“…Establishing a diagnosis of chronic PJI is challenging due to atypical symptoms, which may lead to infection with delayed healing, severe bone defects, joint dysfunction and even a higher risk of short-term mortality [3]. To date, there was no "gold standard" tests or protocol for diagnosing chronic PJI [4]. So, an accurate and timely diagnosis of chronic PJI is a key step toward implementing an effective treatment.…”

“…They also need to be supplemented by more speci c tests, such as synovial uid analysis, microbial culture, and histopathology. Among them, the detection of synovial uid (such as IL-6, CD64, and alpha-defensin) has shown great attraction in recent studies [4,6,7]. CRP is one of the most widely used in ammatory markers in the identi cation of infectious diseases, which is synthesized primarily in liver hepatocytes but also by smooth muscle cells, macrophages, endothelial cells, lymphocytes, and adipocytes [8,9].…”