Procalcitonin and α-Defensin for Diagnosis of Periprosthetic Joint Infections

Current Status and Perspectives of Diagnosis and Treatment of Periprosthetic Joint Infection

Periprosthetic joint infection (PJI) is a catastrophic complication following joint replacement surgery, posing significant challenges to orthopedic surgeons. Due to the lack of a definitive diagnostic gold standard, timely treatment initiation is problematic, resulting in substantial economic burdens on patients and society. In this review, we thoroughly analyze the complexities of PJI and emphasize the importance of accurate diagnosis and effective treatment. The article specifically focuses on the advancements in diagnostic techniques, ranging from traditional pathogen culture to advanced molecular diagnostics, and discusses their role in enhancing diagnostic accuracy. Additionally, we review the latest surgical management strategies, including everything from debridement to revision surgeries. Our summary aims to provide practical information for the diagnosis and treatment of PJI and encourages further research to improve diagnostic accuracy and treatment outcomes.

Management of septic arthritis and prosthetic joint infection

Management of joint infection is an evolving topic. This article reviews the literature on the management of native and prosthetic joint infection and suggests some areas of improvement in short- and long-term management which could lead to better patient outcomes. Surgical management is the mainstay of treatment for native or prosthetic knee infection and aspiration should only be used for diagnostic purposes. A multidisciplinary team approach and compliance with national guidelines, alongside referral networks and pooling of expertise, should be mandatory to improve patient outcomes.

Diagnosis of Periprosthetic Joint Infection: The Utility of Biomarkers in 2023

Periprosthetic joint infection (PJI) is a rare yet devastating complication following total joint arthroplasty (TJA). Early and accurate diagnosis of PJI is paramount in order to maximize the chances of successful treatment. However, we are yet to identify a single "gold standard" test for the diagnosis of PJI. As a result, the diagnosis of PJI is often challenging. Currently, the 2018 ICM definition of PJI is the only validated diagnostic criteria available. This article will review the importance of serum and synovial biomarkers in the diagnosis of PJI. In addition, it will provide a brief overview of the emerging modalities for the identification of infections in this setting.

Profiling the Immune Response to Periprosthetic Joint Infection and Non-Infectious Arthroplasty Failure

Arthroplasty failure is a major complication of joint replacement surgery. It can be caused by periprosthetic joint infection (PJI) or non-infectious etiologies, and often requires surgical intervention and (in select scenarios) resection and reimplantation of implanted devices. Fast and accurate diagnosis of PJI and non-infectious arthroplasty failure (NIAF) is critical to direct medical and surgical treatment; differentiation of PJI from NIAF may, however, be unclear in some cases. Traditional culture, nucleic acid amplification tests, metagenomic, and metatranscriptomic techniques for microbial detection have had success in differentiating the two entities, although microbiologically negative apparent PJI remains a challenge. Single host biomarkers or, alternatively, more advanced immune response profiling-based approaches may be applied to differentiate PJI from NIAF, overcoming limitations of microbial-based detection methods and possibly, especially with newer approaches, augmenting them. In this review, current approaches to arthroplasty failure diagnosis are briefly overviewed, followed by a review of host-based approaches for differentiation of PJI from NIAF, including exciting futuristic combinational multi-omics methodologies that may both detect pathogens and assess biological responses, illuminating causes of arthroplasty failure.

Role of Biomarkers in Periprosthetic Joint Infections

Periprosthetic joint infection (PJI) is one of the most serious complications after joint arthroplasty. The incidence rate of PJI after total joint replacement is 1-3%. Although there are different guidelines and diagnostic criteria used to diagnose PJI, diagnosing PJI is a highly difficult process for orthopedists. The current Musculoskeletal Infection Society (MSIS) criteria are widely used for the diagnosis of PJI. These criteria include results from blood/synovial fluid tests, physical examination, and histological and microbiological analyses of intra-operative samples. However, there is currently no blood or synovial test that can definitively diagnose PJI. To make a more effective diagnosis of PJI, a large number of studies have explored and continue to investigate biomarkers. This review aims to provide general information about serum and synovial markers used for the diagnosis of PJI that may be used to create a database to guide researchers in new studies.

Extra-pulmonary applications of procalcitonin: an updated literature review

INTRODUCTION

: Procalcitonin (PCT) is a biomarker with established performance in the differentiation between bacterial and viral infections, predominantly in pulmonary infections, as well as the diagnosis and prognosis of bacterial sepsis. However, the role of PCT in extra-pulmonary infections is not well described.

AREAS COVERED

: We reviewed the role of PCT in commonly experienced extra-pulmonary infections including meningitis, diabetic foot infection, prosthetic joint infection, osteomyelitis, and skin and soft tissue infection. PubMed and Medline online libraries were searched, from 2013 till 2022, for relevant articles.

EXPERT OPINION

: For meningitis, PCT could distinguish bacterial from viral meningitis. PCT distinguished septic arthritis from different types of arthritis but had variable performance in discriminating septic arthritis from crystal arthropathy. For periprosthetic joint infections, results were inconclusive. PCT had a potential role in diagnosis of more complex infections such as osteomyelitis and diabetic foot infections, but further studies are needed for a definitive cutoff. In skin and soft tissue infections, PCT performance was more variable requiring further investigation to define cutoff for the discrimination of cellulitis from necrotizing fasciitis. We find that PCT performed best for meningitis and helps in the reduction of unnecessary antibiotic treatment, but has variable outcomes with other extra-pulmonary infections.

Diagnosing Periprosthetic Joint Infection: a Scoping Review

PURPOSE OF REVIEW

The goal of this review is to provide an up to date understanding of the utility and limitations of the current tests utilized in the diagnosis of periprosthetic joint infection (PJI) in total knee and hip arthroplasty.

RECENT FINDINGS

Despite the growth in literature surrounding PJI diagnosis, there remains challenges in establishing a diagnosis of PJI. A combination of clinical, serum, and synovial tests and microbiologic and histologic examinations can yield a diagnosis in the majority of cases. Novel molecular and imaging studies may be beneficial for indeterminant cases. A number of emerging diagnostic tests have been proposed and may be incorporated into diagnostic algorithms in the future. Recently proposed stepwise diagnostic algorithms have shown high sensitivity and specificity. The diagnosis of PJI remains challenging due to a lack of tests that can definitively rule out infection. Diagnosis and investigations should occur in a stepwise fashion. There has been a plethora of new diagnostic tests introduced in attempts to improve the accuracy of diagnostic algorithms. The definition and algorithms for the diagnoses of PJI will continue to evolve as new techniques and tests are introduced.

Human transcriptomic response to periprosthetic joint infection

Periprosthetic joint infection (PJI), a devastating complication of total joint replacement, is of incompletely understood pathogenesis and may sometimes be challenging to clinically distinguish from other causes of arthroplasty failure. We characterized human gene expression in 93 specimens derived from surfaces of resected arthroplasties, comparing transcriptomes of subjects with infection- versus non-infection-associated arthroplasty failure. Differential gene expression analysis confirmed 28 previously reported potential biomarkers of PJI, including bactericidal/permeability increasing protein (BPI), cathelicidin antimicrobial peptide (CAMP), C-C-motif chemokine ligand 3 (CCL3), 4(CCL4) and C-X-C-motif chemokine ligand 2 (CXCL2), colony stimulating factor 2 receptor beta (CSF2RB), colony stimulating factor 3 (CSF3), alpha-defensin (DEFA4), Fc fragment of IgG receptor 1B (CD64B), intercellular adhesion molecule 1 (ICAM1), interferon gamma (IFNG), interleukin 13 receptor subunit alpha 2 (IL13RA2), interleukin 17D (IL17D), interleukin 1 (IL1A, IL1B, IL1RN), interleukin 2 receptors (IL2RA, IL2RG), interleukin 5 receptor (IL5RA), interleukin 6 (IL6), interleukin 8 (IL8), lipopolysaccharide binding protein (LBP), lipocalin (LCN2), lactate dehydrogenase C (LDHC), lactotransferrin (LTF), matrix metallopeptidase 3 (MMP3), peptidase inhibitor 3 (PI3), and vascular endothelial growth factor A (VEGFA), and identified three novel molecules of potential diagnostic use for detection of PJI, namely C-C-motif chemokine ligand CCL20, coagulation factor VII (F7), and B cell receptor FCRL4. Comparative analysis of infections caused by staphylococci versus bacteria other than staphylococci and Staphylococcus aureus versus Staphylococcus epidermidis showed elevated expression of interleukin 13 (IL13), IL17D, and MMP3 in staphylococcal infections, and of IL1B, IL8, and platelet factor PF4V1 in S. aureus compared to S. epidermidis infections. Pathway analysis of over-represented genes suggested activation of host immune response and cellular maintenance and repair functions in response to invasion of infectious agents. The data presented provides new potential targets for diagnosis of PJI and for differentiation of PJI caused by different infectious agents.

Diagnosis of orthopaedic-implant-associated infections caused by slow-growing Gram-positive anaerobic bacteria - a clinical perspective

Slow-growing Gram-positive anaerobic bacteria (SGAB) such as Cutibacterium acnes are increasingly recognized as causative agents of implant-associated infections (IAIs) in orthopaedic surgeries. SGAB IAIs are difficult to diagnose because of their non-specific clinical and laboratory findings as well as the fastidious growth conditions required by these bacteria. A high degree of clinical suspicion and awareness of the various available diagnostic methods is therefore important. This review gives an overview of the current knowledge regarding SGAB IAI, providing details about clinical features and available diagnostic methodologies. In recent years, new methods for the diagnosis of IAI were developed, but there is limited knowledge about their usefulness in SGAB IAI. Further studies are required to determine the ideal diagnostic methodology to identify these infections so that they are not overlooked and mistakenly classified as aseptic failure.

Diagnostic values of HNP 1-3 and procalcitonin levels in synovial fluid aspirates in the differential diagnosis between septic arthritis and noninfectious arthritis

INTRODUCTION

Although early diagnosis of septic arthritis may reduce mortality rates, and limit unnecessary surgical interventions, clinical parameters alone are not adequate for making the diagnosis of septic arthritis. Therefore, relevant laboratory parameters are used to enhance diagnostic sensitivity. The aim of our study was to assist in making the diagnosis of septic arthritis, and prevent delays in the diagnosis. For this purpose; we aimed to determine the diagnostic values of human neutrophil peptides 1-3 (HNP 1-3) and procalcitonin (PCT) in synovial fluids of patients with arthritis. By comparing the HNP 1-3 and procalcitonin levels, as well as CRP, in synovial fluid aspirates, we evaluated the significance of these data in the differential diagnosis of septic arthritis from noninfectious arthritis.

METHODS

A total of 67 adults consisting of 37 septic arthritis and 30 noninfectious arthritis patients were included in our study. As bioindicators; levels of HNP 1-3, PCT, synovial and serum CRP levels were found to have significant ROC areas in discriminating septic arthritis patients from noninfectious arthritis patients.

RESULTS

As a result, synovial fluid HNP 1-3 levels were significantly higher in septic arthritis patients compared to noninfectious arthritis patients (p < 0.001). The sensitivity, specificity, and accuracy of HNP 1-3 levels in the diagnosis of septic and noninfectious arthritis were found as 86%, 87%, and 87%, respectively (AUC of the ROC curve = 0.828).

CONCLUSIONS

It was decided that the level of HNP 1-3 in the synovial fluid can be used as an alternative indicator in the diagnosis of septic arthritis.

Serum and Synovial Biomarkers for the Diagnosis of Implant-Associated Infection After Orthopedic Surgery

Implant-associated infection is one of the most devastating complications following orthopedic surgery. Early identification is crucial for treatment. Currently, however, a reliable diagnostic tool is lacking, partly due to disparate bacteria colonies (virulent vs non-virulent), difficulty in distinguishing infection from inflammatory disease, and highly diverse diagnostic thresholds and testing methods. Given the importance of biomarkers in the initial screening for the infection, an extensive effort has been made to develop serum and synovial biomarkers. In this review, the authors summarize the results from the most relevant studies to provide comprehensive information on biomarkers for the diagnosis of implant-associated infection. [Orthopedics. 2021;44(2):e158-e166.].

Alpha-defensins determination in different types of synovial fluid and parallel collected serum samples by ELISA

AIMS

The study aims were to verify the serum (S) and synovial fluid (SF) reference intervals (RIs) for human neutrophil defensins (HNP1-3); measure S and SF defensin concentrations in different types of SF, including non-inflammatory, inflammatory non-pyogenic, inflammatory pyogenic, and hemorrhagic; and to compare the HNP1-3 concentrations in SF and S with those of other inflammatory biomarkers.

METHODS

SF and S samples were collected from 92 patients. HNP1-3 concentrations were determined using enzyme-linked immunosorbent assays; glucose, lactate, interleukin-6, and procalcitonin using an automatic analyzer; and presepsin using a Pathfast system. There were 61 non-inflammatory, 11 inflammatory non-pyogenic, 11 inflammatory pyogenic, and 9 hemorrhagic SF. Non-inflammatory SF was divided into non-inflammatory normal and non-inflammatory osteoarthritis. The former was used to estimate the HNP1-3 RI in SF and S.

RESULTS

The estimated HNP1-3 RIs of SF and S were 12.47-437.42 mg/L and 5.45-44.75 µg/L, respectively. HNP1-3 differed significantly between S and SF and individual groups of SF (P<0.001 and P=0.001, respectively). There were significant relationships between SF HNP1-3 and S HNP1-3 (P<0.001), S C-reactive protein (P<0.001), and S interleukin-6 (P=0.007), and between SF HNP1-3 and SF C-reactive protein (P=0.004) and SF interleukin-6 (P<0.001). The highest kappa coefficient was between SF HNP1-3 and SF interleukin-6 (κ=0.507).

CONCLUSIONS

We validated the SF HNP1-3 diagnostic kit and demonstrated that SF and S HNP1-3 are promising biomarkers for distinguishing inflammatory from non-inflammatory joint diseases.

The Expanding Role of Biomarkers in Diagnosing Infection in Total Joint Arthroplasty: A Review of Current Literature

Consistent diagnosis of periprosthetic infection in total joint arthroplasty continues to elude the orthopedic surgeon because no gold standard test exists. Therefore clinicians must rely on a combination of tests to help aid the diagnosis. The expanding role of biomarkers has shown promising results to more accurately diagnose an infection when combined with clinical suspicion and bacterial culture testing. This paper reviews the diagnostic capabilities of the most current serum and synovial biomarkers as well as next generation sequencing in the setting of periprosthetic joint infection. Future research and high-powered studies will be necessary to determine sensitivity and specificity of each biomarker.

Is there a role of tranexamic acid in rheumatoid arthritis with total knee arthroplasty? Findings from a multicenter prospective cohort study in China

BACKGROUND

Tranexamic acid (TXA) has proven to be effective in reducing the blood loss associated with total knee arthroplasty (TKA) in patients with osteoarthritis. However, there still exists a paucity of evidence regarding the effectiveness of intravenous TXA in patients with rheumatoid arthritis. The aim of this study was to explore the efficacy and safety of intravenous TXA on blood loss after TKA in Chinese patients with rheumatoid arthritis.

MATERIALS AND METHODS

A total of 405 patients with rheumatoid arthritis who had undergone TKA were categorized into two groups based on the protocol of TXA use. TXA group (n = 248): patients received 15 mg/kg TXA prior to operation. Control group (n = 157): patients received no TXA. The outcome measurements such as, total blood loss (TBL), intraoperative blood loss (IBL), hidden blood loss (HBL), transfusion, drainage, the timing of first ambulation, the length of stay (LOS), total hospitalization costs, the results of 12-Item Short Form Survey (SF-12), the incidence of thromboembolic events and other complications were recorded and compared.

RESULTS

The mean TBL, IBL, HBL, volume of transfusion and drainage were significantly lower in TXA group than in Control group. The rate of transfusion was significantly lower in TXA group than in Control group. There was a favorable effect in early ambulation for patients in TXA group, compared with patients in Control group. In addition, TXA group had shorter LOS, lower hospitalization costs and higher postoperative SF-12 score than Control group. The incidence of deep venous thrombosis and other complications did not differ between the two groups.

CONCLUSION

TXA can effectively diminish blood loss, reduce transfusion, shorten LOS and decrease hospitalization costs after TKA in Chinese patients with rheumatoid arthritis, without increasing the risk of complications.

Single-stage versus two-stage revision for shoulder periprosthetic joint infection: a systematic review and meta-analysis

BACKGROUND

Shoulder periprosthetic joint infection (PJI) is a significant complication after arthroplasty with high morbidity. An evidence-based algorithm for the treatment of shoulder PJI is lacking in current practice. The purpose of this systematic review and meta-analysis was to understand and compare the role of single- and 2-stage shoulder arthroplasty revision for PJI.

METHODS

A comprehensive literature review was performed to identify all studies related to shoulder arthroplasty for PJI in PubMed, Scopus, and EMBASE. Inclusion criteria for this systematic review were studies that reported on single- or 2-stage revision, with infection eradication and a minimum follow-up of 12 months and a minimum of 5 patients for analysis. A random-effects meta-analysis was performed, and heterogeneity was assessed with Cochrane Q and I2.

RESULTS

A total of 13 studies reporting on single-stage revision and 30 studies reporting on 2-stage revision were included in final analysis. The majority of positive cultures from single-stage revision for PJI resulted in Cutibacterium acnes with 113 of 232 (48.7%) reported cases compared with 190 of 566 (33.7%) reported cases for 2-stage revision. However, there was a lower percentage of methicillin-resistant Staphylococcus aureus positive cultures, with 2.5% for single-stage compared with 9.7% for 2-stage revision. The overall pooled random-effect reinfection incidence was 0.05 (95% confidence interval: 0.02-0.08), with moderate heterogeneity (I² = 34%, P = .02). The reinfection rate was 6.3% for single-stage and 10.1% for 2-stage revision, but this was not significant (Q = 0.9 and P = .40).

CONCLUSION

Based on a systematic review with meta-analysis, single-stage revision for shoulder PJI is an effective treatment. Indeed, our analysis showed single-stage to be more effective than 2-stage, but this is likely confounded by a treatment bias given the higher propensity of virulent and drug-resistant bacteria treated with 2-stage in the published literature. This implies that shoulder surgeons treating PJI can be reassured of a low recurrence rate (6.3%) when using single-stage treatment for C acnes or other sensitive, low-virulence organisms.

Predictive values of the postoperative neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and lymphocyte-to-monocyte ratio for the diagnosis of early periprosthetic joint infections: a preliminary study

Background

Several studies have been conducted to report diagnostic values of the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR) in the many diseases, such as oncological, inflammatory, and some infectious diseases. However, the predictive value of these laboratory parameters for early periprosthetic joint infections (PJIs) has not yet been reported. The aim of this study was to determine predictive values of the postoperative NLR, PLR, and LMR for the diagnosis of PJIs.

Methods

In this retrospective study, 104 patients (26 early PJI cases and 78 non-PJI cases) who underwent total joint arthroplasty were enrolled in this study. All the patients were then categorized into two groups: PJI group, patients with the diagnosis of PJI (26 patients; 14 males, 12 females; mean age = 65.47 ± 10.23 age range = 51–81 ) and non-PJI group, patients without PJI (78 patients; 40 males, 38 females; mean age = 62.15 ± 9.33, age range = 41–92). We defined “suspected time” as the time that any abnormal symptoms or signs occurred, including fever, local swelling, or redness around the surgical site between 2 and 4 weeks after surgery and before the diagnosis. Suspected time and laboratory parameters, including NLR, PLR, LMR, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), were compared between both groups. The trends of postoperative NLR, LMR, PLR, CRP, and ESR were also reviewed. The predictive ability of these parameters at the suspected time for early PJI was evaluated by multivariate analysis and receiver operating characteristic (ROC) curve analysis.

Results

NLR, PLR, and LMR returned to preoperative levels within 2 weeks after surgery in the two groups. In the PJI group, NLR and PLR were significantly increased during the incubation period of infection or infection, and LMR was significantly reduced, although 61.5% (16/26) of the patients had normal white blood cells. Interestingly, ESR and CRP were still relatively high 2 weeks after surgery and were not different between the two groups before infection started (p = 0.12 and 0.4, respectively). NLR and PLR were significantly correlated with early PJI (Odds ratios for NLR and PLR = 88.36 and 1.12, respectively; p values for NLR and PLR = 0.005 and 0.01, respectively). NLR had great predictive ability for the diagnosis of early PJI, with a cut-off value of 2.77 (sensitivity = 84.6%, specificity = 89.7%, 95% CI = 0.86–0.97).

Conclusions

ESR and CRP seem not to be sensitive for the diagnosis of early PJI due to their persistently high levels after arthroplasty. The postoperative NLR at the suspected time may have a great ability to predict early PJI.

Accuracy of blood-tests and synovial fluid-tests in the diagnosis of periprosthetic joint infections

INTRODUCTION

Periprosthetic joint infection (PJI) is one of the most complex complications following total joint arthroplasty. Despite significant progress in recent years, the use of blood and synovial biomarkers to diagnose PJI remains a challenge.

AREAS COVERED

A combination of serological, synovial, microbiological, histological, and radiological investigations is suggested by consensus and international guidelines. Novel biomarkers and molecular methods have shown promise in recent years. The purpose of this review is to provide an update about the biomarkers used to diagnose PJI and highlight their sensitivity and specificity. In addition, guidance on the diagnostic steps and clinical workflow will be included.

EXPERT OPINION

The diagnostic algorithm developed and validated by the international consensus meeting group is still the most valuable resource to approach PJI diagnosis. The current combination of blood and synovial biomarkers yield acceptable results and good performance. However, there is a need for new biomarkers and further research to understand the limitations of current tests better, as well as explore new options such as alpha-defensin, D-dimer, interleukin-6, and leukocyte esterase.

Meta-analysis in periprosthetic joint infection: a global bibliometric analysis

Background

Periprosthetic joint infection (PJI) is the most serious complication of joint replacement surgery. Further comorbidities include bedsore, deep vein thrombosis, reinfection, or even death. An increasing number of researchers are focusing on this challenging complication. The aim of the present study was to estimate global PJI research based on bibliometrics from meta-analysis studies.

Methods

A database search was performed in PubMed, Scopus, and Web of Science. Relevant studies were assessed using the bibliometric analysis.

Results

A total of 117 articles were included. The most relevant literature on PJI was found on Scopus. China made the highest contributions to global research, followed by the USA and the UK. The institution with the most contributions was the University of Bristol. The journal with the highest number of publications was The Journal of Arthroplasty, whereas the Journal of Clinical Medicine had the shortest acceptance time. Furthermore, the top three frequently used databases were Embase, MEDLINE, and Cochrane. The most frequent number of authors in meta-analysis studies was four. Most studies focused on the periprosthetic hip and knee. The alpha-defensin diagnostic test, preventive measures on antibiotics use, and risk factors of intra-articular steroid injections were the most popular topic in recent years.

Conclusion

Based on the results of the present study, we found that there was no single database that covered all relevant articles; the optimal method for bibliometric analysis is a combination of databases. The most popular research topics on PJI focused on alpha-defensin, antibiotic use, risk factors of intra-articular steroid injections, and the location of prosthetic hip and knee infection.

New developments and future challenges in prevention, diagnosis, and treatment of prosthetic joint infection

Prosthetic joint infection (PJI) is a devastating complication that results in substantial costs to society and patient morbidity. Advancements in our knowledge of this condition have focused on prevention, diagnosis, and treatment, in order to reduce rates of PJI and improve patient outcomes. Preventive measures such as optimization of patient comorbidities, and perioperative antibiotic usage are intensive areas of current clinical research to reduce the rate of PJI. Improved diagnostic tests such as synovial fluid (SF) α-defensin enzyme-linked immunosorbent assay, and nucleic acid-based tests for serum, SF, and tissue cultures, have improved diagnostic accuracy and organism identification. Increasing the diversity of available antibiotic therapy, immunotherapy, and alternative implant coatings remain promising treatments to improve infection eradication in the setting of PJI.

Alpha-Defensin-1 in Synovial Fluid is Useful for Diagnosis of Joint Infection

The distinction between bacterial infectious and noninfectious arthritis is typically challenging in the early stages; however, it is critical for treatment decision making. Here, we investigated the diagnostic relevance of alpha- and beta-defensin levels in serum and synovial fluid as biomarkers of joint infection in patients presenting with fever and arthritis. The study included 12 patients who presented with fever (≥37°C) and arthritis (pain in the knee or hip joint). The diagnostic criteria for periprosthetic joint infection proposed by the Musculoskeletal Infection Society were used to detect joint infection and categorize the patients into infection and non-infection groups. Alpha-defensin-1 and beta-defensin-3 levels in serum and synovial fluid were measured using enzyme-linked immunosorbent assay. No significant between-group difference was observed with respect to serum alpha-defensin-1 levels; however, synovial fluid alpha-defensin-1 levels were significantly higher in the infection group (33.6 ± 26.2 ng/ml) than in the non-infection group (0.9 ± 0.4 ng/ml). No significant between-group differences were observed with respect to serum or synovial fluid beta-defensin-3 levels. Furthermore, synovial fluid alpha-defensin-1 levels were increased in patients without prosthesis in the infection group. In conclusion, in patients with fever and arthritis, synovial fluid alpha-defensin-1 levels were significantly higher in patients with infectious arthritis than in those with noninfectious arthritis. Therefore, synovial fluid alpha-defensin-1 levels is a useful diagnostic marker for joint infection.

Does the Alpha Defensin ELISA Test Perform Better Than the Alpha Defensin Lateral Flow Test for PJI Diagnosis? A Systematic Review and Meta-analysis of Prospective Studies

BACKGROUND

Periprosthetic joint infection (PJI) following total joint arthroplasty is a serious complication that causes severe morbidity and adds a major financial burden to the healthcare system. Although there is plenty of research on the alpha-defensin (AD) test, a meta-analysis consisting of only prospective studies investigating AD's diagnostic efficacy has not been performed. Additionally, some important subgroups such as THA and TKA have not been separately analyzed, particularly regarding two commonly used versions of the AD test, the laboratory-based (ELISA) and lateral-flow (LF).

QUESTIONS/PURPOSES

(1) Does the AD ELISA test perform better in the detection of PJI than the AD LF test, in terms of pooled sensitivity and specificity, when including prospective studies only? (2) Are there differences in sensitivity or specificity when using AD ELISA and AD LF tests for PJI diagnosis of THA or TKA PJI separately?

METHODS

Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, we included prospective studies describing the use of either AD test in the workup of pain after total joint arthroplasty (primary or revision, but not after resection arthroplasty). Fifteen studies (AD ELISA: 4; AD LF: 11) were included, with 1592 procedures. Subgroup data on THA and TKA could be retrieved for 1163 procedures (ELISA THA: 123; LF THA: 257; ELISA TKA: 228; LF TKA: 555). Studies not describing THA or TKA, those not using Musculoskeletal Infection Society (MSIS) criteria as the standard for determining the presence or absence of PJI, those not clearly reporting data for the AD test for the total cohort, and those describing data published in another study were excluded. Studies were not excluded based on follow-up duration; the MSIS criteria could be used within a few weeks, when test results were available. Quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 criteria. Study quality was generally good. The most frequent sources of bias were related to patient selection (such as unclear inclusion and exclusion criteria) and flow and timing (uncertainty in place and time of aspiration, for example). Heterogeneity was moderate to high; a bivariate random-effects model therefore was used. To answer both research questions, sensitivity and specificity were calculated for AD ELISA and LF test groups and THA and TKA subgroups, and were compared using z-test statistics and meta-regression analysis.

RESULTS

No differences were found between the AD ELISA and the AD LF for PJI diagnosis in the pooled cohorts (THA and TKA combined), in terms of sensitivity (90% versus 86%; p = 0.43) and specificity (97% versus 96%; p = 0.39). Differences in sensitivity for PJI diagnosis were found between the THA and TKA groups for the AD ELISA test (70% versus 94%; p = 0.008); pooled AD LF test sensitivity did not differ between THA and TKA (80% versus 87%; p = 0.20). No differences in specificity were found in either subgroup.

CONCLUSIONS

Both the AD ELISA and AD LF test can be used in clinical practice because both have high sensitivity and very high specificity for PJI diagnosis. The lower sensitivity found for diagnosis of PJI in THA for the AD ELISA test must be carefully interpreted because the pooled data were heterogenous and only two studies for this group were included. Future research should analyze TKAs and THAs separately to confirm or disprove this finding.

LEVEL OF EVIDENCE

Level II diagnostic study.

Calprotectin discriminates septic arthritis from pseudogout and rheumatoid arthritis

OBJECTIVE

We aimed to determine whether calprotectin and α-defensins could discriminate septic from other inflammatory arthritides.

METHODS

Synovial fluids with a predominance of neutrophils from patients with septic arthritis, pseudogout and RA were prospectively collected. Neutrophil-related proteins calprotectin and human neutrophil α-defensins levels were assessed in synovial fluids. Demographic parameters and biomarkers with P-value ⩽0.05 for differentiating septic from non-septic arthritis were included in a multivariable model. Multivariable logistic regression with stepwise selection was performed to build the final combined model.

RESULTS

A total of 74 patients were included: septic arthritis (n = 26), pseudogout (n = 28) and RA (n = 20). Patients with septic arthritis were more likely to be male and young, and to display higher synovial neutrophil count. Calprotectin was significantly increased in patients with septic arthritis. The multivariable model included calprotectin, synovial fluid neutrophil count and gender. Calprotectin was the only biomarker that discriminated septic arthritis from non-septic inflammatory arthritides, with 76% sensitivity, 94% specificity and a positive likelihood ratio = 12.2 at the threshold for calprotectin of 150 mg/l.

CONCLUSION

Synovial fluid calprotectin is a relevant biomarker to discriminate septic arthritis from other inflammatory arthritides. This biomarker should be tested in an independent cohort.

The Results of Two-stage Revision for Methicillin-resistant Periprosthetic Joint Infection (PJI) of the Hip

Introduction:

Periprosthetic joint infection (PJI) of the hip due to methicillin-resistant bacteria is difficult to treat and remain a challenge for arthroplasty surgeon.

Material and Methods:

Retrospective review was done to the patients who received two-stage revisions with an antibiotic loaded cement-spacer for PJI of the hip between January 2010 to May 2015. We found 65 patients (65 hips) with positive culture findings. Eight patients were lost to follow-up and excluded from the study. Among the rest of the 57 patients, methicillin-resistant infection (MR Group) was found in 28 cases. We also evaluate the 29 other cases that caused by the other pathogen as control group. We compared all of the relevant medical records and the treatment outcomes between the two groups.

Results:

The mean of follow-up period was 33.7 months in the methicillin-resistant group and 28.4 months in the control group (p = 0.27). The causal pathogens in the methicillin-resistant group were: Methicillin-resistant Staphylococcus aureus (MRSA) in 10 cases, Methicillin-resistant Staphylococcus epidermidis (MRSE) in 16 cases and Methicillin-resistant coagulase-negative Staphylococcus (MRCNS) in two cases. The reimplantation rate was 92.8% and 89.6% in the methicillin-resistant and control group, respectively (p= 0.66). The rates of recurrent infection after reimplantation were 23.1% (6/26) in the methicillin-resistant group and 7.6% (2/26) in the control group (p= 0.12). The overall infection control rate was 71.4% (20/28) and 89.6% (26/29) in the methicillin-resistant and control group, respectively (p = 0.08). Both groups showed comparable baseline data on mean age, BMI, gender distribution, preoperative ESR/CRP/WBC and comorbidities.

Conclusions:

Two-stage revision procedure resulted in low infection control rate and high infection recurrency rate for the treatment of methicillin-resistant periprosthetic joint infection (PJI) of the hip. Development of the treatment strategy is needed to improve the outcome of methicillin-resistant periprosthetic joint infection (PJI) of the hip.

Reliability of synovial fluid alpha-defensin and leukocyte esterase in diagnosing periprosthetic joint infection (PJI): a systematic review and meta-analysis

BACKGROUND

Synovial fluid proteins had been applied as diagnostic biomarkers for periprosthetic joint infection (PJI) in recent research papers. Thus, this meta-analysis aimed to estimate the diagnostic efficiency of synovial fluid α-defensin and leukocyte esterase (LE) for PJI.

METHODS

We conducted our systematic review by searching the keywords in online databases such as PubMed, Embase, Cochrane, Elsevier, Springer, and Web of Science from the time of database inception to October 2018. Inclusion criteria were as follows: patients who have undergone knee, hip, or shoulder joint replacements; α-defensin or leukocyte esterase (LE strip) of synovial fluid was detected as the biomarker for PJI diagnosis; and Musculoskeletal Infection Society (MSIS) or utilizing a combination of clinical data was considered as the gold standard. Diagnostic parameters including sensitivity, specificity, diagnostic odds ratio (DOR), and area under the summary of receiver operating characteristics curve (AUSROC) were calculated for the included studies to evaluate the synovial fluid α-defensin and LE for PJI diagnosis.

RESULTS

After full-text review, 28 studies were qualified for this systematic review, 16 studies used α-defensin and the other 12 were conducted using LE strip. The pooled sensitivity, specificity, and DOR of LE strip were 87% (95% CI 84-90%), 96% (95% CI 95-97%), and 170.09 (95% CI 97.63-296.32), respectively, while the pooled sensitivity, specificity, and DOR of α-defensin were 87% (95% CI 83-90%), 97% (95% CI 96-98%), and 158.18 (95% CI 74.26-336.91), respectively. The AUSROC for LE strip and α-defensin were 0.9818 and 0.9685, respectively.

CONCLUSION

Both LE strip and α-defensin of synovial fluid provide rapid and convenient diagnosis for PJI. Sensitivity of α-defensin and LE strip are the same, while both these two methods have high specificity in clinical practice.

Synovial fluid α-defensin in the diagnosis of periprosthetic joint infection: the lateral flow test is an effective intraoperative detection method

Background

Synovial fluid α-defensin is a valuable biomarker for periprosthetic joint infection (PJI). Its diagnostic value for PJI has been widely evaluated recently, but results are inconsistent, especially for different test methods. The objective of this study was to evaluate the diagnostic value of laboratory-based immunoassay and lateral flow testing for the detection of α-defensin against hip and knee PJI.

Methods

We systematically searched MEDLINE and EMBASE for articles on the diagnostic accuracy of α-defensin for PJI published up to September 2018. The pooled sensitivity, specificity, area under the curve (AUC), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were calculated for the evaluation of the diagnostic value of α-defensin for PJI.

Results

Nineteen studies were included. Eleven evaluated laboratory-based immunoassay, and 10 evaluated the lateral flow test results. The pooled sensitivity, specificity, AUC, PLR, NLR, and DOR of laboratory-based immunoassays were 0.96 (95% confidence interval [CI] 0.90–0.98), 0.97 (95% CI 0.95–0.99), 0.99 (95% CI 0.98–1.00), 35.0 (95% CI 18.5–66.2), 0.04 (95% CI 0.02–0.11), and 811 (95% CI 220–2990), respectively. The pooled sensitivity, specificity, AUC, PLR, NLR, and DOR of the lateral flow test were 0.86 (95% CI 0.81–0.91), 0.96 (95% CI 0.93–0.98), 0.95 (95% CI 0.93–0.97), 21.2 (95% CI 11.7–38.5), 0.14 (95% CI 0.10–0.21), and 148 (95% CI 64–343), respectively.

Conclusions

Laboratory-based immunoassay of α-defensin is highly accurate for the diagnosis of hip and knee PJI. The lateral flow test is less sensitive but still a useful intraoperative detection tool for PJI.

Proceedings from the 2018 International Consensus Meeting on Orthopedic Infections: evaluation of periprosthetic shoulder infection

The Second International Consensus Meeting on Orthopedic Infections was held in Philadelphia, Pennsylvania, in July 2018. More than 800 experts from all 9 subspecialties of orthopedic surgery and allied fields of infectious disease, microbiology, and epidemiology were assembled to form the International Consensus Group. The shoulder workgroup reached consensus on 27 questions related to culture techniques, inflammatory markers, and diagnostic criteria used to evaluate patients for periprosthetic shoulder infection. This document contains the group's recommendations and rationale for each question related to evaluating periprosthetic shoulder infection.

The W.A.I.O.T. Definition of High-Grade and Low-Grade Peri-Prosthetic Joint Infection

The definition of peri-prosthetic joint infection (PJI) has a strong impact on the diagnostic pathway and on treatment decisions. In the last decade, at least five different definitions of peri-prosthetic joint infection (PJI) have been proposed, each one with intrinsic limitations. In order to move a step forward, the World Association against Infection in Orthopedics and Trauma (W.A.I.O.T.) has studied a possible alternative solution, based on three parameters: 1. the relative ability of each diagnostic test or procedure to Rule OUT and/or to Rule IN a PJI; 2. the clinical presentation; 3. the distinction between pre/intra-operative findings and post-operative confirmation. According to the WAIOT definition, any positive Rule IN test (a test with a specificity > 90%) scores +1, while a negative Rule OUT test (a test with a sensitivity > 90%) scores −1. When a minimum of two Rule IN and two Rule OUT tests are performed in a given patient, the balance between positive and negative tests, interpreted in the light of the clinical presentation and of the post-operative findings, allows to identify five different conditions: High-Grade PJI (score ≥ 1), Low-Grade PJI (≥0), Biofilm-related implant malfunction, Contamination and No infection (all scoring < 0). The proposed definition leaves the physician free to choose among different tests with similar sensitivity or specificity, on the basis of medical, logistical and economic considerations, while novel tests or diagnostic procedures can be implemented in the definition at any time, provided that they meet the required sensitivity and/or specificity thresholds. Key procedures to confirm or to exclude the diagnosis of PJI remain post-operative histological and microbiological analysis; in this regard, given the biofilm-related nature of PJI, microbiological investigations should be conducted with proper sampling, closed transport systems, antibiofilm processing of tissue samples and explanted biomaterials, and prolonged cultures. The proposed WAIOT definition is the result of an international, multidisciplinary effort. Next step will be a large scale, multicenter clinical validation trial.

Synovial fluid interleukin-16, interleukin-18, and CRELD2 as novel biomarkers of prosthetic joint infections

Objectives

Prosthetic joint infection (PJI) diagnosis is a major challenge in orthopaedics, and no reliable parameters have been established for accurate, preoperative predictions in the differential diagnosis of aseptic loosening or PJI. This study surveyed factors in synovial fluid (SF) for improving PJI diagnosis.

Methods

We enrolled 48 patients (including 39 PJI and nine aseptic loosening cases) who required knee/hip revision surgery between January 2016 and December 2017. The PJI diagnosis was established according to the Musculoskeletal Infection Society (MSIS) criteria. SF was used to survey factors by protein array and enzyme-linked immunosorbent assay to compare protein expression patterns in SF among three groups (aseptic loosening and first- and second-stage surgery). We compared routine clinical test data, such as C-reactive protein level and leucocyte number, with potential biomarker data to assess the diagnostic ability for PJI within the same patient groups.

Results

Cut-off values of 1473 pg/ml, 359 pg/ml, and 8.45 pg/ml were established for interleukin (IL)-16, IL-18, and cysteine-rich with EGF-like domains 2 (CRELD2), respectively. Receiver operating characteristic curve analysis showed that these factors exhibited an accuracy of 1 as predictors of PJI. These factors represent potential biomarkers for decisions associated with prosthesis reimplantation based on their ability to return to baseline values following the completion of debridement.

Conclusion

IL-16, IL-18, and CRELD2 were found to be potential biomarkers for PJI diagnosis, with SF tests outperforming blood tests in accuracy. These factors could be useful for assessing successful debridement based on their ability to return to baseline values following the completion of debridement.Cite this article: M-F. Chen, C-H. Chang, L-Y. Yang, P-H. Hsieh, H-N. Shih, S. W. N. Ueng, Y. Chang. Synovial fluid interleukin-16, interleukin-18, and CRELD2 as novel biomarkers of prosthetic joint infections. Bone Joint Res 2019;8:179-188. DOI: 10.1302/2046-3758.84.BJR-2018-0291.R1.

Diagnostic Accuracy of Serum, Synovial, and Tissue Testing for Chronic Periprosthetic Joint Infection After Hip and Knee Replacements: A Systematic Review

BACKGROUND

Chronic periprosthetic joint infection (PJI) is a devastating complication that can occur following total joint replacement. Patients with chronic PJI report a substantially lower quality of life and face a higher risk of short-term mortality. Establishing a diagnosis of chronic PJI is challenging because of conflicting guidelines, numerous tests, and limited evidence. Delays in diagnosing PJI are associated with poorer outcomes and morbid revision surgery. The purpose of this systematic review was to compare the diagnostic accuracy of serum, synovial, and tissue-based tests for chronic PJI.

METHODS

This review adheres to the Cochrane Collaboration's diagnostic test accuracy methods for evidence searching and syntheses. A detailed search of MEDLINE, Embase, the Cochrane Library, and the grey literature was performed to identify studies involving the diagnosis of chronic PJI in patients with hip or knee replacement. Eligible studies were assessed for quality and bias using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Meta-analyses were performed on tests with sufficient data points. Summary estimates and hierarchical summary receiver operating characteristic (HSROC) curves were obtained using a bivariate model.

RESULTS

A total of 12,616 citations were identified, and 203 studies met the inclusion criteria. Of these 203 studies, 170 had a high risk of bias. Eighty-three unique PJI diagnostic tests were identified, and 17 underwent meta-analyses. Laboratory-based synovial alpha-defensin tests and leukocyte esterase reagent (LER) strips (2+) had the best performance, followed by white blood-cell (WBC) count, measurement of synovial C-reactive protein (CRP) level, measurement of the polymorphonuclear neutrophil percentage (PMN%), and the alpha-defensin lateral flow test kit (Youden index ranging from 0.78 to 0.94). Tissue-based tests and 3 serum tests (measurement of interleukin-6 [IL-6] level, CRP level, and erythrocyte sedimentation rate [ESR]) had a Youden index between 0.61 to 0.75 but exhibited poorer performance compared with the synovial tests mentioned above.

CONCLUSIONS

The quality of the literature pertaining to chronic PJI diagnostic tests is heterogeneous, and the studies are at a high risk for bias. We believe that greater transparency and more complete reporting in studies of diagnostic test results should be mandated by peer-reviewed journals. The available literature suggests that several synovial fluid-based tests perform well for diagnosing chronic PJI and their use is recommended in the work-up of any suspected case of chronic PJI.

LEVEL OF EVIDENCE

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Comparison of Synovial Fluid and Serum Procalcitonin for Diagnosis of Periprosthetic Joint Infection: A Pilot Study in 32 Patients

Background

Periprosthetic joint infection (PJI) remains challenging since a “gold standard” for diagnosis has not yet been established. This study aimed to evaluate the accuracy of synovial fluid procalcitonin (SF-PCT) and serum procalcitonin as a diagnostic biomarker for PJI and to compare its accuracy against standard methods.

Methods

A prospective cohort study was conducted during 2015–2017 in 32 patients with painful hip or knee arthroplasty who have underwent revision surgery. Relevant clinical and laboratory data were collected. PJI was diagnosed based on the 2013 international consensus criteria. Preoperative blood sample and intraoperatively acquired joint fluid were taken for PCT measurement with a standard assay. Diagnostic accuracy was analyzed by the receiver-operating characteristic curve and the area under the curve (AUC).

Results

Twenty patients (62.5%) were classified as the PJI group, and 12 (37.5%) were classified as the aseptic loosening group. The median age was 68 years (range 38–87 years). The median values of SF-PCT and serum PCT in the PJI group were both significantly higher than those in the aseptic loosening group: the median serum PCT levels (interquartile range: IQR) were 0.33 ng/mL (0.08-2.79 ng/mL) in the PJI group compared with 0.04 ng/mL (0.03-0.06 ng/mL), and the median SF-PCT levels (IQR) were 0.16 ng/mL (0.12-0.26 ng/mL) in PJI group compared with 0.00 (0.00-0.00 ng/mL) (p < 0.001, both). SF-PCT, with a cut-off level of 0.08 ng/mL, had an AUC of 0.87, a sensitivity of 90.0%, a specificity of 83.3%, and a negative likelihood ratio (LR-) of 0.12. Serum PCT, with a standard cut-off level of 0.5 ng/mL, had an AUC of 0.70, a sensitivity of 40.0%, a specificity of 100.0%, and a LR- of 0.60.

Conclusion

SF-PCT appears to be a reliable test and could be useful as an alternative indicator or in combination with standard methods for diagnosing PJI.

Qualitative Alpha-defensin Versus The Main Available Tests For The Diagnosis Of Periprosthetic Joint Infection: Best Predictor Test?

Introduction: Biomarkers such as α-defensin demonstrated to be a potentially useful option in periprosthetic joint infection (PJI) diagnosis. Recently, a new point-of-care test for α-defensin level detection in synovial fluid has been commercialized in Europe. The aim of this study is to compare the α-defensin test (SynovasureTM) diagnostic ability with the main available clinical tests for periprosthetic joint infection diagnosis in a practical clinical setting of a Bone Infection Unit. Methods: Between 2015 and 2017, 146 patients with suspected chronic PJI were screened with SynovasureTM. Seventy-three of these met the Musculoskeletal Infection Society (MSIS) criteria and were included in the analysis. According to MSIS criteria, 40 patients (54.7%) were classified as infected and 33 (45.3%) as not infected. The results obtained with SynovasureTM were recorded and compared with standard diagnostic methods for PJI diagnosis. Results: SynovasureTM showed a sensitivity of 85.0 % (95% CI 70.2 to 94.3) and a specificity of 96.9 % (95% CI 83.8 to 99.9) for PJI detection. The positive likelihood ratio of SynovasureTM was 27.2 (95% CI 3.9 to 188.1) and the negative likelihood ratio was 0.2 (95% CI 0.1 to 0.3). The diagnostic odds ratio was 181.3 (95% CI 20.7 to 1590.4). SynovasureTM demonstrated a statistical significant difference when compared to Erythrocyte Sedimentation Rate (ESR) and C-reactive Protein (CRP) specificity (at least one positive test) and preoperative culture sensitivity (1 positive culture). Conclusion: Our findings show that SynovasureTM sensitivity is lower than quantitative α-D test, but when compared to the main available tests shows a good specificity and the highest DOR. On the SF it is the easier test to do, due to the fact that it needs a minimal amount of SF and it is not limited by blood contamination or antibiotic use. Whereas there is no single standalone test, SynovasureTM should be considered a reliable additional test for periprosthetic joint infection diagnosis in everyday clinical practice.

Clinical Evaluation of Synovial Alpha Defensin and Synovial C-Reactive Protein in the Diagnosis of Periprosthetic Joint Infection

BACKGROUND

Diagnosing periprosthetic joint infection after total joint arthroplasty is often challenging. The alpha defensin test has been recently reported as a promising diagnostic test for periprosthetic joint infection. The goal of this study was to determine the diagnostic accuracy of alpha defensin testing.

METHODS

One hundred and eighty-three synovial alpha defensin and synovial fluid C-reactive protein (CRP) tests performed in 183 patients undergoing evaluation for periprosthetic joint infection were reviewed. Results were compared with the Musculoskeletal Infection Society (MSIS) criteria for periprosthetic joint infection.

RESULTS

Alpha defensin tests were performed prior to surgical treatment for infection, and 37 of these patients who had these tests were diagnosed by MSIS criteria as having infections. Among this group, the alpha defensin test had a sensitivity of 81.1% (95% confidence interval [CI], 64.8% to 92.0%) and a specificity of 95.9% (95% CI, 91.3% to 98.5%). There were 6 false-positive results, 4 of which were associated with metallosis. There were 7 false negatives, all of which were associated with either draining sinuses (n = 3) or low-virulence organisms (n = 4). A combined analysis of alpha defensin and synovial fluid CRP tests was performed in which a positive result was represented by a positive alpha defensin test and a positive synovial fluid CRP test (n = 28). Among this group, the sensitivity was calculated to be 73.0% (95% CI, 55.9% to 86.2%) and the specificity was calculated to be 99.3% (95% CI, 96.2% to 99.9%). An additional combined analysis was performed where a positive result was represented by a positive alpha defensin test or positive synovial fluid CRP test (n = 64). Among this group, the sensitivity was calculated to be 91.9% (95% CI, 78.1% to 98.3%) and the specificity was calculated to be 79.5% (95% CI, 72.0% to 85.7%).

CONCLUSIONS

Alpha defensin in combination with synovial fluid CRP demonstrates very high sensitivity for diagnosing periprosthetic joint infection, but may yield false-positive results in the presence of metallosis or false-negative results in the presence of low-virulence organisms. When both alpha defensin and synovial fluid CRP tests are positive, there is a very high specificity for diagnosing periprosthetic joint infection.

LEVEL OF EVIDENCE

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Alpha-defensin and the Synovasure lateral flow device for the diagnosis of prosthetic joint infection: a systematic review and meta-analysis

Aims

The aim of this review was to evaluate the available literature and to calculate the pooled sensitivity and specificity for the different alpha-defensin test systems that may be used to diagnose prosthetic joint infection (PJI).

Materials and Methods

Studies using alpha-defensin or Synovasure (Zimmer Biomet, Warsaw, Indiana) to diagnose PJI were identified from systematic searches of electronic databases. The quality of the studies was evaluated using the Quality Assessment of Studies of Diagnostic Accuracy (QUADAS) tool. Meta-analysis was completed using a bivariate model.

Results

A total of 11 eligible studies were included. The median QUADAS score was 13 (interquartile range 13 to 13) out of 14. Significant conflicts of interest were identified in five studies. The pooled sensitivity for the laboratory alpha-defensin test was 0.95 (95% confidence interval (CI) 0.91 to 0.98) and the pooled specificity was 0.97 (95% CI 0.95 to 0.98) for four studies with a threshold level of 5.2 mgl-1 The pooled sensitivity for the lateral flow cassette test was 0.85 (95% CI 0.74 to 0.92) and the pooled specificity was 0.90 (95% CI 0.91 to 0.98). There was a statistically significant difference in sensitivity (p = 0.019), but not specificity (p = 0.47).

Conclusion

Laboratory-based alpha-defensin testing remains a promising tool for diagnosing PJI. The lateral flow cassette has a significantly lower performance and pooled results are comparable to the leucocyte esterase test. Further studies are required before the widespread adoption of the lateral flow cassette alpha-defensin test. Cite this article: Bone Joint J 2018;100-B:703-11.

Diagnostic accuracy of the alpha defensin lateral flow device (Synovasure) for periprosthetic infections in microbiologically complex situations: A study of 42 cases in a French referral centre

BACKGROUND

Joint aspiration is currently the reference standard test for diagnosing periprosthetic joint infection (PJI) despite the high rate of false-negative results, of which a major cause is the fastidious nature of some microorganisms. A rapid diagnostic test that detects alpha defensin (Synovasure™, Zimmer, Warsaw, IN, USA) in joint fluid can provide the diagnosis of PJI within a few minutes across the full spectrum of causative organisms (including mycobacteria and yeasts). Its performance in detecting bacterial infections is unaltered by concomitant antibiotic therapy. Few studies of Synovasure™ have been conducted by groups that were involved in designing the test, which has not been validated in France. Assessments in referral centres where complex microbiological situations are common hold considerable interest. The objective of this prospective study was to determine the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and causes of error of Synovasure™ used to diagnose periprosthetic infection in complex microbiological situations.

HYPOTHESIS

The rapid diagnostic test Synovasure™ has greater than 90% NPV for detecting periprosthetic infections in complex microbiological infections.

MATERIAL AND METHODS

Synovasure™ was used 42 times in 39 patients between October 2015 and October 2017 in challenging microbiological situations [discordant joint aspiration results (n=20), negative cultures with clinical or laboratory evidence of infection, (n=21), and concomitant antibiotic therapy (n=1)]. Of the 39 patients, 23 had total knee prostheses, 13 total hip prostheses, and 3 total femoral prostheses. The reference standard to which the Synovasure™ results were compared was the PJI criteria set developed by the Musculoskeletal Infection Society (MSIS).

RESULTS

Synovasure™ was negative in 30 cases with negative joint fluid cultures (30/42, 71.4%). Of the 12 (28.6%) cases with positive Synovasure™ results, only 7 (7/12, 58.3%) had positive joint fluid cultures. According to the MSIS criteria 9 cases were infected, including 8 with positive and 1 with negative Synovasure™ results. Of the 33 cases that were not infected according to MSIS criteria, 29 had negative and 3 positive Synovasure™ results; the remaining case had a positive Synovasure™ result but was excluded when metallosis was found intra-operatively. NPV was 96.7%, PPV 72.7%, sensitivity 88.9%, and specificity 90.6%.

DISCUSSION

The high NPV of Synovasure™ suggests a role for this test in microbiologically complex situations as a new tool for ruling in and, most importantly, ruling out infection in doubtful cases.

LEVEL OF EVIDENCE

III, prospective study of diagnostic accuracy.

Synovial Calprotectin: An Inexpensive Biomarker to Exclude a Chronic Prosthetic Joint Infection

BACKGROUND

To diagnose or exclude a chronic prosthetic joint infection (PJI) can be a clinical challenge. Therefore, sensitive and specific biomarkers are needed in the diagnostic work-up. Calprotectin is a protein with antimicrobial properties and is released by activated neutrophils, making it a specific marker for infection. Because of its low costs and ability to obtain a quantitative value as a point of care test, it is an attractive marker to use in clinical practice. In addition, the test is already used in routine care in most hospitals for other indications and therefore easy to implement.

METHODS

Between June 2015 and June 2017 we collected synovial fluid of all consecutive patients who underwent revision surgery of a prosthetic joint because of chronic pain with or without prosthetic loosening. Synovial calprotectin was measured using a lateral flow immunoassay. A PJI was defined by the diagnostic criteria described by the Musculoskeletal Infection Society.

RESULTS

Fifty-two patients with chronic pain were included. A PJI was diagnosed in 15 of 52 (29%) patients. The median calprotectin in the PJI group was 859 mg/L (interquartile range 86-1707) vs 7 mg/L (interquartile range 3-25) in the control group (P < .001). With a cut-off value of 50 mg/L, synovial calprotectin showed a sensitivity, specificity, positive predictive value, and negative predictive value of 86.7%, 91.7%, 81.3%, and 94.4%, respectively.

CONCLUSION

Synovial calprotectin is a useful and cheap biomarker to use in the diagnostic work-up of patients with chronic pain, especially to exclude a PJI prior to revision surgery.

Synovasure 'quick test' is not as accurate as the laboratory-based α-defensin immunoassay: a systematic review and meta-analysis

AIMS

α-defensin is a biomarker which has been described as having a high degree of accuracy in the diagnosis of periprosthetic joint infection (PJI). Current meta-analyses are based on the α-defensin laboratory-based immunoassay rather than the quick on-table lateral flow test kit. This study is the first meta-analysis to compare the accuracy of the α-defensin laboratory-based immunoassay and the lateral flow test kit for the diagnosis of PJI.

MATERIALS AND METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Inclusion criteria were all clinical studies where the diagnosis of PJI was uncertain. All studies selected used the Musculoskeletal Infection Society (MSIS) or modified MSIS criteria. Two independent reviewers reviewed the studies and extracted data. A meta-analysis of results was carried out: pooled sensitivity, specificity, positive and negative likelihood ratio, heterogeneity and areas under curves are reported.

RESULTS

Ten studies (759 patients) were included. Of these, seven studies (640 patients) evaluated the laboratory-based α-defensin immunoassay and three (119 patients) the lateral flow test. The pooled sensitivity and specificity of the qualitative α-defensin laboratory immunoassay was 0.953 (95% confidence interval (CI) 0.87 to 0.984) and 0.965 (95% CI 0.943 to 0.979) respectively. The pooled positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were 34.86 (95% CI 19.34 to 62.85) and 0.02 (95% CI 0.00 to 0.11). The pooled sensitivity and specificity of the lateral flow test were 0.774 (95% CI 0.637 to 0.870) and 0.913 (95% CI 0.828 to 0.958), respectively. The pooled PLR and NLR were 8.675 (95% CI 4.229 to 17.794) and 0.248 (95% CI 0.147 to 0.418), respectively.

CONCLUSION

The pooled sensitivity and specificity of the lateral flow test were lower than those of the α-defensin laboratory-based immunoassay test. Hence, care must be taken with interpretation of the lateral flow test when relying on its results for the intra-operative diagnosis of PJI. Cite this article: Bone Joint J 2018;100-B:66-72.

The Accuracy of the Alpha Defensin Lateral Flow Device for Diagnosis of Periprosthetic Joint Infection: Comparison with a Gold Standard

BACKGROUND

Alpha defensin is a new biomarker that has been shown to have a very high accuracy to rule out periprosthetic joint infection. Recently, a new rapid lateral flow version of the alpha defensin test was developed and introduced to detect high levels of alpha defensin in synovial fluid quickly and with ease. We conducted a single-center prospective clinical study to compare the results of the Synovasure Alpha Defensin Test with those of the Musculoskeletal Infection Society (MSIS) criteria, which are considered to be the gold standard for diagnosing periprosthetic joint infection.

METHODS

A total of 223 consecutive patients with pain after total hip arthroplasty or total knee arthroplasty were enrolled into the study. In all patients, blood C-reactive protein was measured and joint aspirations were performed. From the synovial fluid, a leukocyte cell count with granulocyte percentage, microbiology cultures, and leukocyte esterase tests were carried out according to the recommendation of the MSIS for diagnosing periprosthetic joint infection. Concurrently, the Synovasure Alpha Defensin Test with a lateral flow device was performed from the aspirate. In the final clinical and statistical evaluation, 191 subjects with 195 joint aspirations (96 hips and 99 knees) were included. According to the MSIS criteria, there were 119 joints with an aseptic revision and 76 joints with periprosthetic joint infection.

RESULTS

After statistical analysis, the overall sensitivity of the Synovasure Alpha Defensin Test was 92.1% (95% confidence interval [CI], 83.6% to 97.1%), the specificity was 100% (95% CI, 97.0% to 100%), the positive predictive value was 100% (95% CI, 94.9% to 100%), and the negative predictive value was 95.2% (95% CI, 89.9% to 98.2%). The overall accuracy of the Synovasure test was 96.9% (95% CI, 93.4% to 98.9%), 189 of 195 cases.

CONCLUSIONS

Our results suggest that the Synovasure periprosthetic joint infection test has a very high accuracy in diagnosing periprosthetic infections after total hip arthroplasty or total knee arthroplasty. Although the Synovasure Alpha Defensin Test does not provide information on the identity of the infectious pathogen, the test does have an important role in recognizing periprosthetic joint infection early and enables surgeons to start proper therapy without delay.

LEVEL OF EVIDENCE

Diagnostic Level I. See Instructions for Authors for a complete description of levels of evidence.

Serum biomarkers in periprosthetic joint infections

OBJECTIVES

The diagnosis of periprosthetic joint infection (PJI) is difficult and requires a battery of tests and clinical findings. The purpose of this review is to summarize all current evidence for common and new serum biomarkers utilized in the diagnosis of PJI.

METHODS

We searched two literature databases, using terms that encompass all hip and knee arthroplasty procedures, as well as PJI and statistical terms reflecting diagnostic parameters. The findings are summarized as a narrative review.

RESULTS

Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were the two most commonly published serum biomarkers. Most evidence did not identify other serum biomarkers that are clearly superior to ESR and CRP. Other serum biomarkers have not demonstrated superior sensitivity and have failed to replace CRP and ESR as first-line screening tests. D-dimer appears to be a promising biomarker, but more research is necessary. Factors that influence serum biomarkers include temporal trends, stage of revision, and implant-related factors (metallosis).

CONCLUSION

Our review helped to identify factors that can influence serum biomarkers' level changes; the recognition of such factors can help improve their diagnostic utility. As such, we cannot rely on ESR and CRP alone for the diagnosis of PJI prior to second-stage reimplantation, or in metal-on-metal or corrosion cases. The future of serum biomarkers will likely shift towards using genomics and proteomics to identify proteins transcribed via messenger RNA in response to infection and sepsis.Cite this article:Bone Joint Res 2018;7:85-93.

Diagnostic accuracy of alpha-defensin in periprosthetic joint infection: a systematic review and meta-analysis

BACKGROUND

Alpha-defensin, a novel biomarker, has shown great potential for the accurate diagnosis of periprosthetic joint infection (PJI) in recent years: many published studies have presented encouraging results. Nevertheless, the diagnostic accuracy of alpha-defensin is inconsistent across published studies. Moreover, the optimum value of the diagnostic threshold urgently needs to be ascertained. This meta-analysis sought to estimate the precision of alpha-defensin for the diagnosis of PJI and, where possible, to confirm the threshold.

METHOD

We systematically searched PubMed, Embase, Cochrane, Web of Knowledge, and ClinicalTrials.gov for relevant literature on alpha-defensin in the diagnosis of PJI (searching publications from the inception of each database until February 2017, with no language restriction). Pooled sensitivity, specificity, diagnostic odds ratios, and likelihood ratios were the indexes used for assessment, with the use of a random-effects model.

RESULT

Eleven of the 426 studies that evaluated the diagnostic accuracy of alpha-defensin in periprosthetic joint infection (PJI) were included in this analysis. The pooled diagnostic sensitivity of alpha-defensin for PJI was 0.96 (95% confidence interval [CI], 0.87 to 0.99) and the specificity was 0.95 (95% CI, 0.91 to 0.97). Since there was substantial heterogeneity among studies, based on the inconsistency index (I²), threshold, site of arthroplasty, study design and techniques for the alpha-defensin test, subgroup analyses were performed to estimate the impacts of these variables on heterogeneity.

CONCLUSION

In summary, this meta-analysis clearly lends support to the conclusion that alpha-defensin is a promising addition to the current methods for diagnosis of PJI.

Serum and Synovial Fluid Interleukin-6 for the Diagnosis of Periprosthetic Joint Infection

A gold standard for diagnosis of periprosthetic joint infection (PJI) has not yet been established. The objective of this study was to evaluate the diagnostic value of serum and synovial fluid interleukin (IL)-6 levels for PJI. The MEDLINE and EMBASE databases were searched for studies describing PJI diagnosis using serum and synovial fluid IL-6 and published between January 1990 and October 2016. Seventeen studies were included in the analysis. The pooled sensitivities of serum and synovial fluid IL-6 were 0.72 (95% confidence interval [CI]: 0.63–0.80) and 0.91 (95% CI: 0.82–0.96), respectively. The pooled specificities of serum and synovial fluid IL-6 were 0.89 (95% CI: 0.77–0.95) and 0.90 (95% CI: 0.84–0.95), respectively. The pooled diagnostic odds ratios (DORs) of serum and synovial fluid IL-6 were 20 (95% CI: 7–58) and 101 (95% CI: 28–358), respectively, and the pooled areas under the curve (AUCs) were 0.83 (95% CI: 0.79–0.86) and 0.96 (95% CI: 0.94–0.98), respectively. Synovial fluid IL-6 had high diagnostic value for PJI. Although serum IL-6 test was less sensitive than synovial fluid IL-6 test, it may be regularly prescribed for patients with prosthetic failure owing to its high specificity.