Fibrinogen - A Practical and Cost Efficient Biomarker for Detecting Periprosthetic Joint Infection

Efficacy analysis of clinical serological indicators in the diagnosis of postoperative periprosthetic joint infection in patients with rheumatoid arthritis or osteoarthritis

PURPOSE

To investigate the incidence of periprosthetic joint infection (PJI) in patients with rheumatoid arthritis (RA) or osteoarthritis (OA) after primary joint arthroplasty; to analyze the optimal cut-off values of clinical serum markers C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and D-dimer for the diagnosis of PJI in RA patients; and to explore their diagnostic efficacy and clinical significance.

METHODS

Clinical data of 15,702 patients with RA (578) or OA (15,124) who underwent total joint arthroplasty from 2013 to 2021 were retrospectively analyzed. Serum CRP, ESR, and D-dimer were recorded for each patient, and subject characteristic curves were used to determine the optimal threshold values of CRP, ESR, and D-dimer for RA-PJI and OA-PJI and to compare the areas under the curves to assess the diagnostic efficacy of the optimal threshold values of serologic indices for RA-PJI.

RESULTS

The five year incidence of PJI was 6.92% in RA patients and 0.67% in OA patients. The optimal thresholds of CRP, ESR, and D-dimer for the diagnosis of RA-PJI were respectively 13.85 mg/L, 33.02 mm/h, and 796.50 ng/mL. The sensitivities of the optimal thresholds were respectively 67.6%, 62.2%, and 56.8%, and the specificities were 74.7%, 60.4%, and 74.4%.

CONCLUSION

RA patients have a higher incidence of PJI than OA patients. The optimal thresholds for CRP, ESR, and d-dimer for the diagnosis of PJI were higher in RA patients than in OA patients, but the sensitivity and specificity of the diagnosis were not as good as in OA patients.

Serum and Synovial Markers in the Diagnosis of Periprosthetic Joint Infection of the Hip, Knee, and Shoulder: An Algorithmic Approach

➤ No single test has demonstrated absolute accuracy for the diagnosis of periprosthetic joint infection (PJI).➤ Physicians rely on a combination of serological tests, synovial markers, and clinical findings plus clinical judgment to help to guide preoperative decision-making.➤ Several organizations have proposed criteria for the diagnosis of hip or knee PJI on which we now rely.➤ Given that shoulder arthroplasty has only recently become popular, it is possible that a shoulder-specific definition of PJI will be introduced in the coming years.➤ Although a number of serum and synovial markers have demonstrated high accuracy for the diagnosis of PJI of the hip and knee, further research is needed in order to identify markers that may be more suitable for the diagnosis of shoulder PJI and for the potential development and identification of specific serological tests as screening tools for PJI.

Diagnostics in Late Periprosthetic Infections-Challenges and Solutions

The rising number of arthroplasties is combined with a rising number of periprosthetic joint infections, which leads to life-concerning consequences for the patients, including extended antibiotic treatment, further surgery and increased mortality. The heterogeneity of the symptoms and inflammatory response of the patients due to, e.g., age and comorbidities and the absence of a single diagnostic test with 100% accuracy make it very challenging to choose the right parameters to confirm or deny a periprosthetic joint infection and to establish a standardized definition. In recent years, additional diagnostic possibilities have emerged primarily through the increasing availability of new diagnostic methods, such as genetic techniques. The aim of the review is to provide an overview of the current state of knowledge about the various tests, including the latest developments. The combination of different tests increases the accuracy of the diagnosis. Each physician or clinical department must select the tests from the available methods that can be best implemented for them in organizational and technical terms. Serological parameters and the cultivation of the samples from aspiration or biopsy should be combined with additional synovial tests to create an accurate figure for the failure of the prosthesis, while imaging procedures are used to obtain additional information for the planned therapeutic procedure.

To Evaluate the Efficacy of Biomarkers as Monitoring Tool in Patients with Fascial Space Infections of Odontogenic Origin: A Clinical Study

Introduction

The objective was to evaluate the efficacy of biochemical markers (WBC, CRP and fibrinogen) and the course of odontogenic space infections in 50 patients.

Material and Methods

Blood samples were taken preoperatively and postoperatively at day 0, day 4, day 8 and day 12 for measuring the levels of all three biomarkers. The trends of the biomarkers were observed and compared with assessment parameters such as dental etiology, number of teeth involved, number of spaces involved, mouth opening and pain. Active pus discharge, dysphagia, hoarseness and swelling were assessed and scored accordingly.

Results

The data were subjected to paired 't' test, McNemar's and Pearson's bivariate correlation as appropriate. Statistical analysis found strong correlation between laboratory values of markers and parameters used to measure severity of infection. All three biomarkers (WBC, CRP and fibrinogen) are significant markers for hospital stay (p < 0.01). Prospective analysis indicates that only one biomarker cannot be used to rule out specific diagnosis.

Conclusion

The combination of three biochemical markers assessed in the present study (WBC, CRP and fibrinogen) should be used as prognostic factor in assessment, clinical severity and efficacy of treatment regime for patients as these can reliably predict the clinical course of odontogenic infection.

Can C-Reactive Protein-Lymphocyte Ratio Be Used as a Screening Tool to Confirm the Diagnosis of Periprosthetic Joint Infection?

Background

This study aimed to investigate whether periprosthetic joint infection (PJI) can be predicted by the C-reactive protein-to-lymphocyte ratio (CLR), whether this ratio increases the accuracy of PJI diagnosis, and whether it is more sensitive than other blood values and ratios.

Methods

The patients were divided into two groups: the septic revision (SR) group and the aseptic revision (AR) group. In cases of septic revision, the diagnosis of PJI was made based on the criteria proposed by the European Bone and Joint Infection Society (EBJIS). The groups were compared in terms of age, sex, body mass index, comorbidity, and preoperative laboratory results. The sensitivity, specificity, and diagnostic performance of the values and ratios were analyzed and compared.

Results

The receiver operating characteristic (ROC) analysis for the CLR gave a diagnostic value of 15.52, which provided a sensitivity of 91.1% and a specificity of 64.2% for PJI. The CLR gave lower specificity and higher sensitivity compared to the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) values. The ROC analysis showed that the CLR had a similar area under the curve (AUC) with the ESR and CRP (0.808). The CLR had a higher specificity than other ratios (platelet volume ratio, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and monocyte-to-lymphocyte ratio) and a higher value of the AUC. In the multivariate analysis, the CLR (hazard ratio, 1.088; 95% confidence interval, 1.063-1.113; p < 0.001) was found to be a significant risk factor. As CLR increased by one unit, the risk of PJI increased by 1.088 times, and it was statistically significant (p < 0.001).

Conclusions

The findings of this study suggest that CLR can serve as a valuable screening tool for diagnosing PJI. CLR demonstrated higher sensitivity in predicting PJI compared to ESR and CRP, and it exhibited greater specificity than other infection markers.

Serum procalcitonin has no significance in the diagnosis of periprosthesis joint infection before total hip and knee replacement

Background

Currently, there is no "gold standard" for early diagnosing PJI. The diagnosis of periprosthetic joint infection (PJI) is a challenging problem in the clinic. As we know, many serum markers have been used in the early diagnosis of PJI. The aim of this study was to validate the value of PCT in the diagnosis of PJI.

Methods

A retrospective review of 77 patients with revision arthroplasties from January 2013 to July 2020 was conducted. PJI was defined using the modified Musculoskeletal Infection Society (MSIS) criteria combined with follow-up results. Besides medical history, clinical and laboratory data was gathered. Preoperative blood was taken for serum PCT and other biomarkers measurement. Receiver operating characteristic (ROC) curves were generated to evaluate the biomarkers' diagnostic performance and optimal cut-off value.

Results

Forty-one patients were identified as the PJI group (27 hips and 14 knees), while thirty-six patients were identified as the aseptic loosening (AL) group (33 hips and 3 knees). The AUCs for C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), Platelets (PLT), Fibrinogen (FIB), and Procalcitonin (PCT) were 0.845 (95% CI 0.755-0.936, p < 0.001), 0.817 (95% CI 0.718-0.916, p < 0.001), 0.728 (95% CI 0.613-0.843, p < 0.001), 0.810 (95% CI 0.710-0.910, p < 0.001) and 0.504 (95% CI 0.373-0.635, p = 0.950), respectively. Higher Area under the Curve (AUC) values were obtained for the combinations of PCT and CRP (AUC = 0.870) (95% CI, 0.774-0.936), PCT and ESR (AUC = 0.817) (95% CI, 0.712-0.896), PCT and PLT (AUC = 0.731) (95% CI, 0.617-0.825), PCT and FIB (AUC = 0.815) (95% CI, 0.710-0.894). The serum PCT indicated a sensitivity of 19.51% and a specificity of 83.33% for diagnosing PJI. When the optimal cut-off value for PCT was set as 0.05 ng/ml, its positive and negative likelihood ratios were 57.1% and 47.6%, respectively.

Conclusion

In conclusion, serum PCT appeared to be no reliable biomarker in differentiating PJI from aseptic loosening before revision arthroplasties. However, PCT combined with other biomarkers further increases the diagnostic accuracy.

Utility of D-dimer in total joint arthroplasty

As the number of patients receiving total joint replacements continues to rise, considerable attention has been directed towards the early detection and prevention of postoperative complications. While D-dimer has long been studied as a diagnostic tool in venous thromboembolism (VTE), this assay has recently received considerable attention in the diagnosis of periprosthetic joint infection (PJI). D-dimer values are substantially elevated in the acute postoperative period after total joint arthroplasty, with levels often exceeding the standard institutional cutoff for VTE (500 µg/L). The utility of D-dimer in detecting VTE after total joint replacement is currently limited, and more research to assess its value in the setting of contemporary prophylaxis protocols is warranted. Recent literature supports D-dimer as a good to excellent biomarker for the diagnosis of chronic PJI, especially when using serum sample technique. Providers should exercise caution when interpreting D-dimer levels in patients with inflammatory and hypercoagulability disorders, as the diagnostic value is decreased. The updated 2018 Musculoskeletal Infection Society criteria, which includes D-dimer levels > 860 µg/L as a minor criterion, may be the most accurate for diagnosing chronic PJI to date. Larger prospective trials with transparent lab testing protocols are needed to establish best assay practices and optimal cutoff values for D-dimer in the diagnosis of PJI. This review summarizes the most current literature on the value of D-dimer in total joint arthroplasty and elucidates areas for future progress.

Complete blood platelet and lymphocyte ratios increase diagnostic accuracy of periprosthetic joint infection following total hip arthroplasty

INTRODUCTION

Systemically, changes in serum platelet to lymphocyte ratio (PLR), platelet count to mean platelet volume ratio (PVR), neutrophil to lymphocyte ratio (NLR) and monocyte to lymphocyte (MLR) represent primary responses to early inflammation and infection. This study aimed to determine whether PLR, PVR, NLR, and MLR can be useful in diagnosing periprosthetic joint infection (PJI) in total hip arthroplasty (THA) patients.

METHODS

A total of 464 patients that underwent revision THA with calculable PLR, PVR, NLR, and MLR in 2 groups was evaluated: 1) 191 patients with a pre-operative diagnosis of PJI, and 2) 273 matched patients treated for revision THA for aseptic complications.

RESULTS

The sensitivity and specificity of PLR combined with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), synovial white blood cell count (WBC) and synovial polymorphonuclear leukocytes (PMN) (97.9%; 98.5%) is significantly higher than only ESR combined with CRP, synovial WBC and synovial PMN (94.2%; 94.5%; p < 0.01). The sensitivity and specificity of PVR combined with ESR, CRP and synovial WBC, and synovial PMN (98.4%; 98.2%) is higher than only ESR combined with CRP, synovial WBC and synovial PMN (94.2%; 94.5%; p < 0.01).

CONCLUSION

The study results demonstrate that both PLR and PVR calculated from complete blood counts when combined with serum and synovial fluid markers have increased diagnostic sensitivity and specificity in diagnosing periprosthetic joint infection in THA patients.

LEVEL OF EVIDENCE

III, case-control retrospective analysis.

The Challenge of Periprosthetic Joint Infection Diagnosis: From Current Methods to Emerging Biomarkers

Due to the increase in the life span and mobility at older ages, the number of implanted prosthetic joints is constantly increasing. However, the number of periprosthetic joint infections (PJIs), one of the most severe complications after total joint arthroplasty, also shows an increasing trend. PJI has an incidence of 1-2% in the case of primary arthroplasties and up to 4% in the case of revision operations. The development of efficient protocols for managing periprosthetic infections can lead to the establishment of preventive measures and effective diagnostic methods based on the results obtained after the laboratory tests. In this review, we will briefly present the current methods used in PJI diagnosis and the current and emerging synovial biomarkers used for the prognosis, prophylaxis, and early diagnosis of periprosthetic infections. We will discuss treatment failure that may result from patient factors, microbiological factors, or factors related to errors during diagnosis.

Decreased serum superoxide dismutase concentration has a high value for the diagnosis of periprosthetic joint infection-a single-center, retrospective study

PURPOSE

As the most serious complication of total knee arthroplasty (TKA), periprosthetic joint infection (PJI) often leads to disastrous consequences. An accurate preoperative diagnosis plays a significant role in saving prostheses and optimizing treatment outcomes. Through this retrospective case-control study, we aimed to investigate the potential of superoxide dismutase (SOD) as a novel serum biomarker in the diagnosis of PJI.

METHODS

We conducted a retrospective review of all patients who underwent TKA and received adequate follow-ups in our hospital from June 2015 to December 2021. A total of 50 patients were enrolled in the PJI group based on the 2018 International Consensus Meeting (ICM) criteria. Besides that, we enrolled 100 patients who underwent TKA in the same period and had a good postoperative course in the control group. Patient characteristics, comorbidities, laboratory results (serum, synovial, and microbial), and intraoperative findings (purulence and histopathology) were documented and compared by univariate analysis. Receiver operating characteristic (ROC) analysis was used to determine the sensitivity, specificity, and diagnostic performance.

RESULTS

The median serum SOD level in the PJI and control group was 135.95 ± 24.47 U/ml (IQR, 111.85-158.30 U/ml) and 173.83 ± 13.9 U/ml (IQR,162.83-183.5 U/ml) (p < 0.05), respectively. With the calculated cutoff of SOD at 149.5U/L, the area under the ROC curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), were 0.919, 0.72, 0.97, 0.923, and 0.874, respectively. In subgroup analysis, the specificity of SOD in diagnosing culture-negative PJI remained extremely high (0.98). Combined diagnosis of serum SOD and C-reactive protein (CRP) made AUC increase to 0.972.

CONCLUSION

Serum SOD showed great potential in the diagnosis of PJI.

Is Fibrinogen a Reliable Biomarker in the Diagnosis of Peri-Prosthetic Joint Infection? A Systematic Review and Meta-Analysis

Background: In recent years, several studies have identified closed correlations between the coagulation cascade and inflammatory mechanisms in infective diseases. Fibrinogen (PF) is emerging as promising biomarker for the diagnosis of peri-prosthetic joint infection (PJI). This study aims to investigate the diagnostic value of PF in diagnosing PJI and to explore potential causes influencing the diagnostic value of PF. Materials and Methods: PubMed, Embase, and Cochrane Library were searched regarding the role of fibrinogen as a biomarker in the diagnosis of PJI. Studies in English were included in the meta-analysis if they determined the diagnostic value of fibrinogen for PJI detection after hip or knee arthroplasty, applying the recognized diagnostic criteria for PJI. A quality evaluation of the studies included was performed. The pooled sensitivity, specificity, likelihood ratios and diagnostic odds ratio (DOR) and the area under the receiver operating characteristic curve (AUROC) were obtained using the statistical software STATA, version 17 (StataCorp, College Station, TX). Results: Ten studies (9 retrospective) were included in the study. Low publication bias was detected, but with high heterogeneity among them. Plasma fibrinogen showed a good diagnostic accuracy and clinical utility in PJI (sensitivity, 0.81 [95% confidence interval {CI}, 0.75-0.86]; specificity, 0.82 [95% CI, 0.76-0.86]; AUROC, 0.88 [95% CI, 0.85-0.91]; DOR, 19 [95% CI, 14-26]). Conclusions: The attempt to find an "ideal" biomarker is crucial to improve the sensitivity and specificity of the current diagnostic algorithms for PJI. The analysis performed in the current study indicates that plasma fibrinogen test is a valid biomarker for PJI diagnosis.

Combination of C-reactive protein and fibrinogen is useful for diagnosing periprosthetic joint infection in patients with inflammatory diseases

BACKGROUND

The screening of periprosthetic joint infection (PJI) in patients with inflammatory diseases before revision arthroplasty remains uncertain. Serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), plasma fibrinogen (FIB), monocyte/lymphocyte ratio, and neutrophil/lymphocyte ratio (NLR) can help screening PJI, but their values in patients with inflammatory diseases have not been determined.

METHODS

Patients with inflammatory diseases who underwent revision hip or knee arthroplasty at West China Hospital, Sichuan University, from January 2008 to September 2020 were divided into infected and non-infected groups based on the 2013 International Consensus Meeting criteria. Sensitivity and specificity of the tested biomarkers for diagnosing infection were determined based on receiver operating characteristic (ROC) curves, and optimal cutoffs were determined based on the Youden index. The diagnostic ability of these biomarkers was re-assessed after combining them with each other.

RESULTS

A total of 62 patients with inflammatory diseases were studied; of them 30 were infected. The area under the ROC curve was 0.813 for CRP, 0.638 for ESR, 0.795 for FIB, and 0.656 for NLR. The optimal predictive cutoff of CRP was 14.04 mg/L with a sensitivity of 86.2% and a specificity of 68.7%, while FIB had a sensitivity of 72.4% and a specificity of 81.2% with the optimal predictive cutoff of 4.04 g/L. The combinations of CRP with FIB produced a sensitivity of 86.2% and specificity of 78.1%.

CONCLUSION

CRP with a slightly higher predictive cutoff and FIB are useful for screening PJI in patients with inflammatory diseases, and the combination of CRP and FIB may further improve the diagnostic values.

TRIAL REGISTRATION

ChiCTR.org.cn, ChiCTR2000039989.

Calprotectin Lateral Flow Test: Consistent Across Criteria for Ruling Out Periprosthetic Joint Infection

BACKGROUND

There are multiple sets of criteria used to define periprosthetic joint infection. The objective of this study is to compare the diagnostic accuracy of the calprotectin lateral flow point-of-care (POC) test in total knee arthroplasty (TKA) patients to diagnose infection using 3 different sets of criteria: (1) 2013 Musculoskeletal Infection Society, (2) 2018 Intentional Consensus Meeting (ICM), and (3) the 2019 proposed European Bone and Joint Infection Society criteria as reference standards.

METHODS

From October 2018 to January 2020, 123 intraoperative synovial fluid samples were prospectively collected from revision total knee arthroplasty patients and tested using a calprotectin lateral flow POC assay. Data were reviewed and adjudicated by 2 independent reviewers blinded to calprotectin test results.

RESULTS

The 3 criteria sets had 91.8% agreement. Using 2013 Musculoskeletal Infection Society criteria, the POC test demonstrated a sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the curve (AUC) of 98.1%, 95.7%, 94.5%, 98.5%, and 0.969, respectively. Using the 2018 ICM, the POC test demonstrated a sensitivity, specificity, PPV, NPV, and AUC of 98.2%, 98.5%, 98.2%, 98.5%, and 0.984, respectively. Using the 2019 proposed European Bone and Joint Infection Society criteria, the POC test demonstrated a sensitivity, specificity, PPV, NPV, and AUC of 93.2%, 100.0%, 100.0%, 94.2%, and 0.966, respectively.

CONCLUSION

The calprotectin lateral flow POC test had excellent sensitivity and specificity across current available periprosthetic joint infection definitions, with the best performance observed when applying 2018 ICM criteria.

LEVEL OF EVIDENCE

Diagnostic I.

A Platelet-Rich Plasma-Derived Biologic Clears Staphylococcus aureus Biofilms While Mitigating Cartilage Degeneration and Joint Inflammation in a Clinically Relevant Large Animal Infectious Arthritis Model

The leading cause of treatment failure in Staphylococcus aureus infections is the development of biofilms. Biofilms are highly tolerant to conventional antibiotics which were developed against planktonic cells. Consequently, there is a lack of antibiofilm agents in the antibiotic development pipeline. To address this problem, we developed a platelet-rich plasma (PRP)-derived biologic, termed BIO-PLY (for the BIOactive fraction of Platelet-rich plasma LYsate) which has potent in vitro bactericidal activity against S. aureus synovial fluid free-floating biofilm aggregates. Additional in vitro studies using equine synoviocytes and chondrocytes showed that BIO-PLY protected these cells of the joint from inflammation. The goal of this study was to test BIO-PLY for in vivo efficacy using an equine model of infectious arthritis. We found that horses experimentally infected with S. aureus and subsequently treated with BIO-PLY combined with the antibiotic amikacin (AMK) had decreased bacterial concentrations within both synovial fluid and synovial tissue and exhibited lower systemic and local inflammatory scores compared to horses treated with AMK alone. Most importantly, AMK+BIO-PLY treatment reduced the loss of infection-associated cartilage proteoglycan content in articular cartilage and decreased synovial tissue fibrosis and inflammation. Our results demonstrate the in vivo efficacy of AMK+BIO-PLY and represents a new approach to restore and potentiate antimicrobial activity against synovial fluid biofilms.

Synovial-Based Tests Outperform Serum Markers to Rule Out Infection in Total Knee Arthroplasty and Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

Total knee arthroplasty (TKA) provides successful results in most patients. Periprosthetic joint infection (PJI) accounts for up to 25% of failed TKAs needing revision. In clinical practice, consensus in diagnostic strategy for excluding or diagnosing PJI is still lacking. In this systematic review and meta-analysis, we aim to provide a simplified data-driven diagnostic strategy for aseptic knee and hip revision surgeons to rule out PJI in the outpatient clinic phase.

METHODS

A literature search in EMBASE, MEDLINE, PubMed, and Cochrane was conducted. Studies involving the diagnosis of PJI in patients with failed TKAs and total hip arthroplasties needing revision were identified. Only studies using the Musculoskeletal Infection Society criteria were included. Quality was assessed using MINORS criteria. Meta-analysis was performed for each diagnostic test identified in the included studies. Pooled estimates of diagnostic accuracy measures were calculated using a bivariate model and plotted in summary receiver-operator characteristic curves. Positive and negative predictive values were calculated in a hypothetical sample of patients with a given disease prevalence.

RESULTS

Twenty-four studies met the inclusion criteria, describing a total of 2974 patients. Quality scores ranged from 13 to 19. Meta-analysis could be performed on 7 unique diagnostic tests. Highest pooled sensitivity and specificity were demonstrated for α-defensin with values of 86% and 96.6%, respectively. α-defensin and white blood cell count in synovial fluid demonstrate highest negative predictive value values.

CONCLUSIONS

We recommend, in a clinical setting with low-intermediate prevalence of PJI, performing arthrocentesis and joint fluid analysis using α-defensin and/or white blood cell count before revision TKA and revision total hip arthroplasty surgery to rule out PJI.

Serum Inflammatory Biomarkers in the Diagnosis of Periprosthetic Joint Infections

Accurate preoperative diagnosis of periprosthetic joint infections (PJIs) can be very challenging, especially in patients with chronic PJI caused by low-virulence microorganisms. Serum parameters, such as serum C-reactive protein (CRP) or the erythrocyte sedimentation rate (ESR), are—among other diagnostic test methods—widely used to distinguish septic from aseptic failure after total hip or knee arthroplasty and are recommended by the AAOS in the preoperative setting. However, they are systemic parameters, and therefore, unspecific. Nevertheless, they may be the first and occasionally the only preoperative indication, especially when clinical symptoms are lacking. They are easy to obtain, cheap, and are available worldwide. In the last decade, different novel serum biomarkers (percentage of neutrophils, neutrophils to lymphocytes ratio, platelet count to mean platelet volume ratio, fibrinogen, D-Dimer, Il-6, PCT) were investigated to find a more specific and accurate serum parameter in the diagnosis of PJI. This article reviews the diagnostic value of established (serum CRP, ESR, WBC) and ‘novel’ serum inflammatory biomarkers (fibrinogen, D-dimer, interleukin-6 (IL-6), procalcitonin, percentage of neutrophils (%N), neutrophils to lymphocytes ratio (NLR), platelet count to mean platelet volume ratio (PC/mPV)) for the preoperative diagnosis of periprosthetic joint infections.

Ability of plasma-based or serum-based assays of D-dimer and FDP for diagnosing periprosthetic joint infection: protocol for a prospective single-centre, parallel comparative study

INTRODUCTION

Several studies have evaluated the diagnostic values of D-dimer and fibrin degradation product (FDP) for detecting periprosthetic joint infection (PJI), but their conclusions have been inconsistent. More importantly, whether the diagnostic value of these two biomarkers differs depending on whether they are assayed in plasma or serum is unclear.

METHODS AND ANALYSIS

This prospective single-centre, parallel comparative study will involve patients planning to undergo revision hip or knee arthroplasty due to an aseptic mechanical failure or PJI. After the patients provide written informed consent, their serum and plasma will be sampled and assayed for D-dimer and FDP. The diagnostic value of these two biomarkers in plasma and serum will be compared with one another and with the value of two traditional inflammatory markers (C reactive protein and erythrocyte sedimentation rate) used to diagnose PJI according to the 2013 International Consensus Meeting criteria. Diagnostic value will be assessed in terms of area under receiver operating characteristic curves, sensitivity, specificity, as well as positive and negative predictive values, all calculated based on the optimal cut-off determined from the Youden index.

ETHICS AND DISSEMINATION

This study was approved by the Ethics Committee of our hospital (approval no. 2020-859). Written informed consent will be obtained from all patients before enrollment. Study findings will be disseminated widely through peer-reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

This study was registered in the Chinese Clinical Trial Registry (ChiCTR2000038547), and it is ongoing.

Synovial Alpha-defensin at Reimplantation in Two-stage Revision Arthroplasty to Rule Out Persistent Infection

BACKGROUND/AIM

Owing to the lack of a diagnostic gold standard, ruling out persistent periprosthetic joint infection (PJI) before second-stage surgery in the setting of two-stage revision arthroplasty constitutes a major challenge. We evaluated if the alpha-defensin-1 (AD-1) test could predict successful infection eradication before reimplantation of a new prosthesis.

PATIENTS AND METHODS

Our prospective study included 20 patients who underwent two-stage revision arthroplasty for treatment of PJI. A standard quantitative enzyme AD-1 immunoassay of synovial fluid, the synovial leukocyte esterase test and routine laboratory blood testing were performed prior to explantation and reimplantation. Treatment failure was defined according to the Delphi-based consensus criteria after a minimum follow-up of 1 year.

RESULTS

A 15% of our patients met the Delphi Criteria within 1 year. None of the markers investigated were significantly different in patients with and without reinfection.

CONCLUSION

Further research is necessary to identify biomarkers more suitable for indicating persistent infection before reimplantation.

The role of fibrinogen in predicting reinfection after DAIR for periprosthetic joint infections

Background

Fibrinogen (FIB) has been found to be a promising marker in diagnosing periprosthetic joint infection (PJI), however, the value of FIB in predicting reinfection of PJI is unknown. The purpose of this study was to evaluate the value of FIB in predicting reinfection after debridement, antibiotics, and implant retention (DAIR) for PJI.

Methods

We retrospectively analyzed the clinical data of patients who were diagnosed with PJI and underwent DAIR from 2013 to 2019. The levels of the FIB, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were measured before DAIR. After DAIR, patients were followed and reinfections were identified. For both acute and chronic PJI, the predictive value of FIB was evaluated by calculating the sensitivity, specificity, and area under the curve (AUC) of the receiver operating characteristic curve (ROC), and was compared with traditional inflammatory markers including ESR and CRP.

Results

The expression of FIB differed between patients reinfected and those not reinfected in both acute and chronic PJI (p < 0.05). In patients who underwent DAIR for acute PJI, the sensitivity and specificity of FIB were 81.82 and 83.33%, respectively, which were significantly higher than that of CRP (sensitivity, 72.73%; specificity, 50%; p < 0.05), while the specificity was higher than that of ESR (specificity, 41.67%; p < 0.05). In patients who underwent DAIR for chronic PJI, the sensitivity and specificity of FIB were 80.00 and 66.66%, respectively, which were significantly higher than that of CRP (sensitivity, 53.33%; specificity, 66.66%; p < 0.05) and ESR (sensitivity was 66.00%; specificity, 16.66%; p < 0.05). The ROC curves showed that FIB demonstrated the highest AUC among the biomarkers in both acute and chronic PJI.

Conclusion

FIB is a promising indicator in predicting reinfection after DAIR for both acute and chronic PJI, and it seems to perform better than ESR and CRP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04357-8.

Role of D-dimer and Fibrinogen in the Diagnosis of Periprosthetic Joint Infection: A Systematic Review and Meta-Analysis

The diagnostic potential of D-dimer and fibrinogen to detect periprosthetic joint infection (PJI) of the hip and knee is not well-understood. The aim of this study was to determine whether D-Dimer and fibrinogen can be used as effective biomarkers to screen PJI. A systematic review of the literature indexed in Web of Science, PubMed, Cochrane Library, Embase, and Google Scholar databases was performed. All studies using D-dimer levels in serum or plasma, or fibrinogen levels in plasma, for the diagnosis of PJI were included. Meta-analysis estimates, including sensitivity, specificity, diagnostic odds ratios (DOR), and the area under the summary receiver operating characteristic curve (AUSROC), were calculated using a random-effects model, and used to assess the diagnostic accuracy of these biomarkers. A total of nine studies were analyzed, and their quality was considered to be acceptable. D-dimer gave a limited diagnostic value if serum and plasma combined: sensitivity (0.77, 95% confidence interval [CI] [0.63 to 0.87]), specificity (0.67, 95% CI [0.54 to 0.78]), DOR (6.81, 95% CI [2.67 to 17.37]), and AUSROC (0.78, 95% CI [0.74 to 0.82]). Plasma D-dimer levels were associated with less satisfactory sensitivity (0.65, 95% CI 0.57 to 0.71), specificity (0.58, 95% CI 0.50 to 0.66), DOR (2.52, 95% CI 1.64 to 3.90), and AUSROC (0.65, 95% CI 0.61 to 0.69). Serum D-dimer levels showed higher corresponding values of 0.89 (95% CI 0.79 to 0.94), 0.76 (95% CI 0.55 to 0.89), 24.24 (95% CI 10.07 to 58.32), and 0.91 (95% CI 0.88 to 0.93). Plasma fibrinogen showed acceptable corresponding values of 0.79 (95% CI 0.70 to 0.85), 0.73 (95% CI 0.57 to 0.85), 10.14 (95% CI 6.16 to 16.70), and 0.83 (95% CI 0.79 to 0.86). Serum D-dimer may be an effective marker for the diagnosis of PJI in hip and knee arthroplasty patients, and it may show higher diagnostic potential than plasma fibrinogen. Plasma D-dimer may have limited diagnostic potential.

Circulating D-Dimer versus Fibrinogen in the Diagnosis of Peri-Prosthetic Joint Infection: A Meta-Analysis

Background: Circulating D-dimer and fibrinogen are both emerging as promising biomarkers for the diagnosis of peri-prosthetic joint infection (PJI), but their clinical values still remain disputable. This study aims to evaluate and compare the accuracy of circulating D-dimer and fibrinogen in the diagnosis of suspected PJI. Methods: We conducted a comprehensive literature search in PubMed, EMBASE, and the Cochrane Library to retrieve diagnostic accuracy studies in which PJI was investigated with circulating D-dimer or fibrinogen from the time of database inception to August 1, 2019. The pooled sensitivity, specificity, likelihood ratios and diagnostic odds ratio (DOR), summary receiver operating characteristic (sROC) curves, and area under the sROC curve (AUC) were constructed using a meta-analysis framework. Results: Seven eligible studies (1,374 patients) were included in the quantitative analysis. The mean levels of circulating D-dimer and fibrinogen were all significantly higher in patients with PJI. The plasma fibrinogen illustrated relatively higher sensitivity (0.84, 95% confidence interval [CI]: 0.78-0.98) and specificity (0.80, 95% CI: 0.76-0.84) than circulating D-dimer (0.74, 95% CI: 0.69-0.78; 0.66, 95% CI: 0.62-0.69, respectively) for the diagnosis of PJI. The pooled DOR of D-dimer, fibrinogen, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) to diagnose PJI was 7.00 (95% CI, 2.50-19.59), 12.40 (95% CI, 5.85 to 26.28), 10.71 (95% CI, 7.76 to 14.78) and 16.22 (95% CI 11.71-22.46), respectively, while the pooled AUC was 0.84 (95% CI, 0.77-0.90), 0.87 (95% CI, 0.85-0.89), 0.82 (95% CI, 0.78-0.85) and 0.87 (95% CI, 0.86-0.88), respectively. Conclusions: This meta-analysis reveals that it could be concluded that plasma fibrinogen is an excellent biomarker for diagnosing PJI, comparable to serum CRP and ESR, while the diagnostic value of circulating D-dimer is only moderate. Large-scale, prospective studies are still needed to confirm current findings.

Plasma fibrinogen in the diagnosis of periprosthetic joint infection

Periprosthetic joint infections (PJIs) have become the most catastrophic complication for patients after arthroplasty. Although previous studies have found that many biomarkers have good performance for diagnosing PJI, early diagnosis remains challenging and a gold standard is lacking. This study aimed to investigate the diagnostic accuracy of plasma fibrinogen (FIB) in detecting PJI compared to other traditional biomarks (CRP, WBC and ESR). A total of 156 patients (including 57 PJI and 99 non-PJI patients) who underwent revision arthroplasty were retrospectively reviewed from 01/2014 to 01/2020. The diagnostic criteria of PJI were mainly based on the definition from the evidence-based definition for periprosthetic joint infection in 2018. The optimal plasma FIB predictive cutoff was 4.20 g/L, the sensitivity of the plasma fibrinogen was 0.860, the specificity was 0.900, the positive predictive value (PPV) was 0.831, and the negative predictive value (NPV) was 0.908. The area under the curve (AUC) value of plasma fibrinogen was 0.916 (95% CI 0.869-0.964), and the CRP, ESR and WBC levels had AUCs of 0.901, 0.822 and 0.647, respectively. Plasma FIB demonstrated better diagnostic strength compared with that of other serum biomarkers before revision arthroplasty. It represents a new horizon for the diagnosis of PJI due to the diagnosis values and cost-effective features.

Fibrinogen performs better than D-dimer for the diagnosis of periprosthetic joint infection: a meta-analysis of diagnostic trials

Purpose

D-dimer and fibrinogen, both belonging to coagulation parameters, are controversial for the diagnosis of periprosthetic joint infection (PJI). This meta-analysis was conducted to compare their diagnostic accuracies for PJI by synthesizing currently available evidence.

Methods

Cochrane Library, MEDLINE, Web of Science, and Embase up to March 1, 2020, and other relevant articles were searched. Five hundred and eighty-one articles were identified after initial research, and 11 studies were included finally. No threshold effects were found between studies. The pooled sensitivity, specificity, and positive and negative likelihood ratio were reported to evaluate the diagnostic performance with heterogeneity analysis. Z test statistics was used to analyze the difference of diagnostic performance between D-dimer and fibrinogen.

Results

The pooled sensitivity, specificity, and positive and negative likelihood ratio of D-dimer for PJI were 0.79 (95% [CI], 0.72–0.85), 0.77 (0.67–0.84), 3.38 (2.21–5.18), and 0.27 (0.18–0.41), respectively. As for fibrinogen, the pooled sensitivity, specificity, and positive and negative likelihood ratio for PJI were 0.75 (0.68–0.80), 0.85 (0.82–0.88), 5.12 (4.22–6.22), and 0.30 (0.23–0.37), respectively. Great heterogeneity was found in studies for D-dimer, and univariate meta-regression analysis revealed that number of involved joints, disease spectrum, comorbidities influencing D-dimer, and sample sources were the source of heterogeneity. Z test found that the pooled specificity of fibrinogen was significantly higher than D-dimer (0.85 ± 0.01 versus 0.77 ± 0.04, p = 0.03). The pooled positive likelihood ratio of fibrinogen was significantly higher than D-dimer (5.12 ± 0.51 versus 3.38 ± 0.74, p = 0.03).

Conclusion

Based on currently available evidence, the meta-analysis suggests that fibrinogen performs better than D-dimer as a rule-in diagnostic tool for its higher specificity. However, more prospective trials with larger size are still needed to provide further confirmation.

Trial registration

This meta-analysis was prospectively registered on PROSPERO (International prospective register of systematic reviews), and the registering number was CRD42020177176.

Reliability of circulating fibrinogen in the diagnosis of prosthesis-related infections: a systematic review and meta-analysis

Background

Fibrinogen (FIB) has recently been used as a biomarker to diagnose periprosthetic joint infection (PJI), but its reliability is still questionable. The aim of this study was to investigate the accuracy of FIB in the diagnosis of PJI after joint replacement.

Methods

We searched for literatures published in PubMed, EMBASE, and the Cochrane Library from the time of database inception to September 2020 and screened the studies according to the inclusion criteria. Then, we calculated the diagnostic parameters of FIB, including the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), area under the curve (AUC), and diagnostic odds ratio (DOR). In addition, we implemented subgroup analyses to identify the sources of heterogeneity.

Results

Seven studies including 1341 patients were selected in our meta-analysis. The pooled sensitivity, specificity, PLR, NLR, and DOR of FIB for PJI diagnosis were 0.78 (95% confidence interval [CI], 0.73–0.82), 0.83 (95% CI, 0.81–0.86), 4.60 (95% CI, 3.30–6.42), 0.24 (95% CI, 0.18–0.34), and 20.13 (95% CI, 14.80–27.36), respectively, while the AUC was 0.896.

Conclusion

The present study indicated that FIB was a reliable detection method and might be introduced into the diagnostic criteria for PJI. However, more robust studies are still needed to confirm the current findings, because most of the included studies were retrospective and had small sample sizes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-020-02171-x.

Inferior performance of established and novel serum inflammatory markers in diagnosing periprosthetic joint infections

Purpose

Besides other diagnostic test methods, established serum inflammatory markers such as serum C-reactive protein or leukocyte count are widely used preoperatively to aid in diagnosing periprosthetic joint infections (PJI). Although low accuracies were reported, these parameters are easily accessible and routinely available. Novel biomarkers with promising results in diagnosing PJI (platelet count to mean platelet volume ratio) or other infectious conditions (percentage of neutrophils, neutrophils to lymphocytes ratio) were described. The purpose of this study was to investigate the diagnostic value of established and novel serum inflammatory biomarkers for the diagnosis of PJI so as to compare the results to find the serum inflammatory marker with the best performance.

Methods

In 177 patients with a previous total hip (n = 91) or knee (n = 86) arthroplasty and indicated revision surgery, the diagnostic value of the routinely available serum inflammatory markers C-reactive protein (CRP), white blood cell count (WBC), percentage of neutrophils (%N), neutrophils to lymphocytes ratio (NLR), fibrinogen and platelet count to mean platelet volume ratio (PC/mPV) were examined retrospectively via receiver operating characteristic curve analysis (AUC). The curves were compared using the z-test.

Results

Sensitivities of serum CRP, WBC, %N, NLR, fibrinogen and PC/mPV were calculated with 68%, 36%, 66%, 63%, 69% and 43%, respectively. Specificities were 87%, 89%, 67%, 73%, 89% and 81%, respectively. Serum CRP (0.78) and fibrinogen (0.79) showed significantly better AUCs compared with serum WBC (0.63), %N (0.67), NLR (0.68) and PC/mPV (0.62) (p < 0.0001). Patients with PJI caused by a low-virulent microorganism (median CRP: 17.6 mg/L) obtained lower CRP levels compared with infections caused by high-virulent microorganisms (median CRP: 49.2 mg/L; p = 0.044). The combination of CRP and fibrinogen showed a better sensitivity (77%) with similar specificity (83%) than one method alone but not at a significant level (CRP (p = 0.200); fibrinogen (p = 0.437)).

Conclusion

Serum CRP and fibrinogen showed the best accuracies among these widely available serum inflammatory parameters. However, due to the insufficient performance, these biomarkers can only be recommended as suggestive criteria in diagnosing PJI. The preoperative workup should always be complemented by more specific tests such as synovial fluid analysis.

Plasma Fibrinogen as a Diagnostic Marker of Infection in Patients with Nonunions

Background

The timely and accurate diagnosis of infected nonunion is challenging, and there is a need for more efficient biomarkers. Previous studies have shown that fibrinogen plays an important role in mediating inflammation in bacterial infections and, therefore, could be a valuable biomarker for infected nonunion. The purpose of this study was to evaluate and compare the performance of plasma fibrinogen and other traditional blood markers for the diagnosis of infected nonunion.

Materials and Methods

We retrospectively studied 146 patients who underwent surgery for primary nonunion between January 2018 and January 2020. The patients were divided into those with infected nonunion (n = 55) and those with aseptic nonunion (n = 91). The preoperatively analyzed parameters were plasma fibrinogen, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) level, and white blood cell (WBC) count. Receiver operating characteristic (ROC) curve analysis was used to assess the sensitivity and specificity of the biomarkers, and Youden's index was calculated to determine their optimal cut-off values.

Results

The plasma fibrinogen values were significantly higher (p < 0.001) in the patients with infected nonunion than in those with aseptic nonunion. ROC curve analysis showed that plasma fibrinogen had a high value of area under the curve (0.816), which indicated that it had good diagnostic ability. Further, at the optimal threshold value of 2.75 g/L, plasma fibrinogen had the highest sensitivity (78.2%; 95% CI = 64.6-87.8) and good specificity (82.4%; 95% CI, 72.7-89.3).

Conclusion

In comparison to the traditional markers of infection, plasma fibrinogen showed good diagnostic ability for the detection of infected nonunion. It may have potential as a practical and cost-efficient biomarker for the diagnosis of infected nonunion.

Current Clinical Methods for Detection of Peri-Prosthetic Joint Infection

Background: Currently, one of the most pressing problems in the field of orthopedic surgery is peri-prosthetic joint infection [PJI]. While there are numerous ways to detect PJI, current clinical detection methods differ across institutions and have varying criteria and protocols. Some of these methods include the Modified Musculoskeletal Infection Society system, culturing, polymerase chain reaction, the determination of the presence of certain biomarkers, testing for the presence of alpha defensin peptides, and leukocyte level testing. Methods: This review summarizes the most recent publications in the field of PJI detection to highlight current strengths as well as provide future directions to find the system for the quickest, cost-effective, and most accurate way to diagnose these types of infections. Results: The results of this literature review suggest that, while each method of diagnosis has its advantages, each has various drawbacks as well. Current methods can be expensive, take days to weeks to complete, be prone to contamination, and can produce ambiguous results. Conclusions: The findings in this review emphasize the need for a more comprehensive and accurate system for diagnosing PJI. In addition, the specific comparison of advantages and drawbacks can be useful for researchers and clinicians with goals of creating new diagnostic tests for PJIs, as well as in clinical scenarios to determine the correct treatment for patients.

Comparison of a Comprehensive Set of Fibrinolytic Markers With C-Reactive Protein and Erythrocyte Sedimentation Rate for the Diagnosis of Periprosthetic Joint Infection

BACKGROUND

The diagnosis of periprosthetic joint infection (PJI), a serious complication after primary total joint arthroplasty, remains challenging. Recently, fibrinolytic activities have been shown to be closely related to infections and inflammation. However, data assessing the value of fibrinolytic markers for the diagnosis of PJI have been sparse until now.

METHODS

We retrospectively enrolled 157 patients undergoing revision for aseptic loosening (n = 106, group A) or revision for chronic PJI (n = 51, group B) from January 2014 to August 2019. PJI was defined using the Musculoskeletal Infection Society criteria. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), D-dimer, fibrin degradation product (FDP), and fibrinogen were measured preoperatively. The diagnostic values of each biomarker were analyzed and compared using receiver operating characteristic curves, sensitivity, and specificity.

RESULTS

Compared with group A, group B had significantly higher levels of CRP, ESR, D-dimer, FDP, and fibrinogen (P < .001). The area under the curve of fibrinogen was 0.914, which was slightly lower than that of CRP (0.924). FDP and D-dimer had area under the curve values of 0.808 and 0.784, respectively. The optimal threshold, sensitivity, and specificity were 3.56 g/L, 86.27%, and 83.96% for fibrinogen; 1.22 mg/L, 66.67%, and 85.85% for D-dimer; and 3.98 μg/mL, 72.55%, and 80.19% for FDP, respectively.

CONCLUSION

Fibrinolytic markers provided promising diagnostic support for PJI, especially fibrinogen, which had a diagnostic efficiency similar to that of CRP and ESR.

Combined serum biomarker analysis shows no benefit in the diagnosis of periprosthetic joint infection

Purpose

In many cases, the diagnosis of a periprosthetic joint infection (PJI) consisting of the clinical appearance, laboratory tests, and other diagnostic tools remains a difficult task. Single serum biomarkers are easy to collect, are suitable for periodical assessment, and are a crucial tool in PJI diagnosis, but limited sensitivity or specificity is reported in literature. The aim of this study was to combine the best-performing single serum biomarkers into a multi-biomarker model aiming to improve the diagnostic properties.

Methods

Within a 27-month period, 124 surgical procedures (aseptic or septic revision total knee arthroplasty (TKA) or total hip arthroplasty (THA)) were prospectively included. The serum leukocyte count, C-reactive protein (CRP), interleukin-6, procalcitonin, interferon alpha, and fibrinogen were assessed 1 day prior to surgery. Logistic regression with lasso-regularization was used for the biomarkers and all their ratios. After randomly splitting the data into a training (75%) and a test set (25%), the multi-biomarker model was calculated and validated in a cross-validation approach.

Results

CRP (AUC 0.91, specificity 0.67, sensitivity 0.90, p value 0.03) and fibrinogen (AUC 0.93, specificity 0.73, sensitivity 0.94, p value 0.02) had the best single-biomarker performances. The multi-biomarker model including fibrinogen, CRP, the ratio of fibrinogen to CRP, and the ratio of serum thrombocytes to CRP showed a similar performance (AUC 0.95, specificity 0.91, sensitivity 0.72, p value 0.01).

Conclusion

In this study, multiple biomarkers were tested for their diagnostic performance, with CRP and fibrinogen showing the best results regarding the AUC, accuracy, sensitivity, and specificity. It was not possible to further increase the diagnostic accuracy by combining multiple biomarkers using sophisticated statistical methods.

A Novel Adjunct Indicator of Periprosthetic Joint Infection: Platelet Count and Mean Platelet Volume

BACKGROUND

Diagnosing a periprosthetic joint infection (PJI) is difficult and often requires a combination of objective findings. The purpose of this study is to determine whether platelets, a known acute phase reactant, would be able to further aid in the diagnosis of PJI.

METHODS

A single-institution retrospective review study was performed on all revision total hip and knee arthroplasties done between 2000 and 2016 (n = 4939). PJI was defined by Musculoskeletal Infection Society criteria (n = 949). Platelet count and mean platelet volume were assessed from each patient's preoperative complete blood count. These values were then assessed as a ratio via receiver operating characteristic (ROC) curve analysis.

RESULTS

The platelet count to mean platelet volume ratio for PJI patients was 33.45 compared to 25.68 for patients in the aseptic revision cohort (P < .001). ROC curve analysis demonstrates that a ratio of 31.70 has a sensitivity of 48.10 (95% confidence interval 44.9-51.4) and a specificity of 80.85 (95% confidence interval 79.6-82.1). This specificity was higher than that of both estimated sedimentation ratio (ESR) and C-reactive protein (CRP) for the same cohorts using optimal values determined via ROC curve analysis. When used in conjunction with ESR and CRP, there was a statistically significant increase in the diagnostic performance of the model used to assess PJI relative to the model that just employed ESR and CRP (P < .05).

CONCLUSION

Our study demonstrates that platelets and their associated serum biomarkers are associated with PJI and warrant consideration in patients who are being evaluated for potential PJI.

Synovial Fluid Viscosity Test is Promising for the Diagnosis of Periprosthetic Joint Infection

BACKGROUND

So far there is no "gold standard" test for the diagnosis of periprosthetic joint infection (PJI), compelling clinicians to rely on several serological and synovial fluid tests with no 100% accuracy. Synovial fluid viscosity is one of the parameters defining the rheology properties of synovial fluid. We hypothesized that patients with PJI may have a different level of synovial fluid viscosity and aimed to investigate the sensitivity and specificity of synovial fluid viscosity in detecting PJI.

METHODS

This prospective study was initiated to enroll patients undergoing primary and revision arthroplasty. Our cohort consisted of 45 patients undergoing revision for PJI (n = 15), revision for aseptic failure (n = 15), and primary arthroplasty (n = 15). PJI was defined using the Musculoskeletal Infection Society criteria. In all patients, synovial fluid viscosity, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and plasma d-dimer levels were measured preoperatively.

RESULTS

The synovial fluid viscosity level was significantly lower (P = .0011) in patients with PJI (7.93 mPa·s, range 3.0-15.0) than in patients with aseptic failure (13.11 mPa·s, range 6.3-20.4). Using Youden's index, 11.80 mPa·s was determined as the optimal threshold value for synovial fluid viscosity for the diagnosis of PJI. Synovial fluid viscosity outperformed CRP, ESR, and plasma d-dimer, with a sensitivity of 93.33% and a specificity of 66.67%.

CONCLUSION

Synovial fluid viscosity seems to be on the same level of accuracy with CRP, ESR, and d-dimer regarding PJI detection and to be a promising marker for the diagnosis of PJI.

Plasma fibrinogen may predict persistent infection before reimplantation in two-stage exchange arthroplasty for periprosthetic hip infection

Background

The diagnosis of persistent infection before reimplantation in two-stage exchange arthroplasty for periprosthetic joint infection (PJI) remains challenging. Currently, several studies suggested coagulation-related markers, such as D-dimer and fibrinogen, may be promising in diagnose of PJI. The purpose of the study was to investigate the predictive values of plasma D-dimer and fibrinogen for assessment of persistent infection before reimplantation hip arthroplasty.

Methods

We retrospectively reviewed 129 hips that treated with two-stage exchange arthroplasty for PJI from 2012 to 2016 in our institution. The persistent infection before reimplantation was based on a modified Musculoskeletal Infection Society (MSIS) criteria. After exclusion, 102 hips were included in the final analysis. Receiver operating characteristic (ROC) curves were generated to determine the prognostic value of plasma D-dimer and fibrinogen in predicting persistent infection before reimplantation.

Results

The area the under ROC curves (AUC) for fibrinogen (0.773; 95% confidential interval [CI], 0.569–0.905) was significantly higher than that of D-dimer (0.565; 95% CI, 0.329–0.777). With the calculated threshold of fibrinogen set at 3.61 g/L, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) was 87.5%, 62.8%, 16.7%, and 98.3%, respectively. With the threshold value of D-dimer set at 0.82 μg/mL, the sensitivity, specificity, PPV, and NPV was 83.3%, 41.9%, 21.7%, and 92.9%, respectively.

Conclusions

In conclusion, the current study reveals that the plasma fibrinogen may be a promising biomarker in predicting persistent infection before reimplantation. Further prospective studies with larger cohorts are needed to validate predictive values and optimal thresholds of coagulation-related markers.