Laboratory-based versus qualitative assessment of α-defensin in periprosthetic hip and knee infections: a systematic review and meta-analysis

Synovial calprotectin in prosthetic joint infection. A systematic review and meta-analysis of the literature

INTRODUCTION

Calprotectin is a protein endowed with antimicrobial properties, rendering it a distinctive marker for infection. Two methods are currently available for the assay of calprotectin: the enzyme-linked immunosorbent assay (ELISA) and the lateral flow test (LFT). We aimed to assess the diagnostic accuracy of synovial fluid calprotectin and to compare the accuracy of the laboratory-based test and the qualitative assessment for the diagnosis of hip and knee prosthetic infection.

MATERIALS AND METHODS

We searched (from inception to November 2023) MEDLINE, Scopus, EMBASE, Web of Science, and Cochrane for studies on calprotectin in the diagnosis of periprosthetic joint infection (PJI). Sensitivity, specificity, positive and negative likelihood ratio (LR), and diagnostic odds ratio were analyzed. The receiver-operating curve for each method was calculated.

RESULTS

We included 14 articles in our meta-analysis, including 902 patients who underwent total hip and knee arthroplasties revision; 331 (37%) had a joint infection according to MSIS, MSIS-modified criteria, ICM 2018 and EBJIS 2021. Considering the false-positive result rate of 6% and false-negative result rate of 7%, pooled sensitivity and specificity were 0.92 (95% CI 0.89-0.94) and 0.93 (0.91-0.95), respectively. The area under the curve (AUC) was 0.93 (95% CI 0.91-0.94). No statistical differences in terms of sensitivity and specificity were found between ELISA and LFT. The pooled sensitivity and specificity of the two calprotectin assessment methods were: LFT 0.90 (95% CI 0.869-0.935) and 0.92 (95% CI 0.894-0.941), respectively; ELISA 0.96 (95% CI 0.914-0.986) and 0.97 (95% CI 0.934-0.988), respectively. The diagnostic odds ratio of the ELISA was superior to that of the LFT (906.6667, 95% CI 271.2686-3030.3712 versus 113.8886, 95% CI 70.4001-184.2414; p < 0.001). The AUC for ELISA and LFT was 0.968 (95% CI 0.944-0.984) and 0.915 (95% CI 0.895-0.933), respectively.

CONCLUSIONS

Detection of synovial calprotectin is an accurate test for diagnosis of hip and knee prosthetic infections. The diagnostic accuracy of the two calprotectin assessment methods is almost comparable. The LFT is a valid, rapid, and more available diagnostic tool, particularly to rule out PJI.

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.

Point of care testing for the diagnosis of periprosthetic joint infections: a review

BACKGROUND

Periprosthetic joint infection (PJI) remains a major complication following total joint arthroplasties (TJA), significantly affecting patient outcomes and healthcare costs. Despite advances in diagnostic techniques, challenges persist in accurately diagnosing PJI, underscoring the need for effective point-of-care testing (POCT).

METHODS

This review examines the current literature and latest developments in POCT for diagnosing PJI, focusing on biomarkers such as alpha-defensin, leukocyte esterase, calprotectin, and C-reactive protein (CRP). Criteria from various societies like the Musculoskeletal Infection Society, Infectious Diseases Society of America, and the International Consensus Meeting were compared to evaluate the effectiveness of these biomarkers in a point-of-care setting.

RESULTS

POCT provides rapid results essential for the timely management of PJI, with alpha-defensin and leukocyte esterase showing high specificity and sensitivity. Recent advancements have introduced novel biomarkers like calprotectin, which demonstrate high diagnostic accuracy. However, challenges such as the variability in test performance and the need for validation under different clinical scenarios remain.

DISCUSSION

While POCT for PJI shows promising results, their integration into clinical practice requires standardized protocols and further validation. The evolution of these diagnostic tools offers a potential shift toward more personalized and immediate care, potentially improving outcomes for patients undergoing TJA.

Upcoming evidence in clinical practice of two-stage revision arthroplasty for prosthetic joint infection

Total joint arthroplasty is the recommended treatment for patients with end-stage osteoarthritis, as it reduces disability and pain and restores joint function. However, prosthetic joint infection is a serious complication of this procedure, with the two-stage exchange being the most common treatment method. While there is consensus on diagnosing prosthetic joint infection, there is a lack of agreement on the parameters that can guide the surgeon in performing definitive reimplantation in a two-stage procedure. One approach that has been suggested to improve the accuracy of microbiologic investigations before definitive reimplantation is to observe a holiday period from antibiotic therapy to improve the accuracy of cultures from periprosthetic tissues, but these cultures report some degree of aspecificity. Therefore, several pieces of evidence highlight that performing reimplantation using continuous antibiotic therapy should be considered a safe and effective approach, leading to higher cure rates and a shorter period of disability. Dosage of C-reactive protein (CRP), erythrocyte sedimentation rate (ERS) and D-dimer are helpful in diagnosing prosthetic joint infection, but only D-dimer has shown sufficient accuracy in predicting the risk of infection recurrence after a two-stage procedure. Synovial fluid analysis before reimplantation has been shown to be the most accurate in predicting recurrence, and new cutoff values for leukocyte count and neutrophil percentage have shown a useful predictive rule to identify patients at risk of unfavourable outcome. A new scoring system based on a numerical score calculated from the beta coefficient derived through multivariate analysis of D-dimer levels, synovial fluid leukocytes and relative neutrophils percentage has demonstrated high accuracy when it comes to guiding the second step of two-stage procedure. In conclusion, reimplantation may be a suitable option for patients who are on continuous therapy without local symptoms, and with CRP and ERS within the normal range, with low synovial fluid leukocytes (< 952/mL) and a low relative neutrophil percentage (< 52%) and D-dimer below 1100 µg/mL. A numerical score derived from analysing these three parameters can serve as a valuable tool in determining the feasibility of reimplantation in these patients.

A paper-based aptamer-sandwich assay for detection of HNP 1 as a biomarker for periprosthetic joint infections on an integrated microfluidic platform

BACKGROUND

Total joint arthroplasty (TJA) has significantly improved the quality of life for millions suffering from end-stage arthritis. However, periprosthetic joint infections (PJI) remain a serious complication, necessitating extensive interventions and prolonged antimicrobial treatments. The aging population is expected to lead to a rise in TJA cases, subsequently increasing the incidence of PJI, particularly in the elderly who face higher mortality rates. Current diagnostic methods for suspected PJI, such as radiographs and biochemical markers like CRP and ESR, exhibit limited sensitivity. Therefore, there is a critical need for a specific synovial fluid biomarker assay to enhance PJI diagnosis using specific SF-based assay.

RESULTS

This study introduces a novel microfluidic chip with a paper-based aptamer-sandwich assay for the quantitative detection of HNP 1, a crucial PJI biomarker, in synovial fluid. The assay leverages the advantages of aptamers over antibodies, demonstrating high selectivity and affinity for target molecules. The integration of a nitrocellulose (NC) membrane onto the microfluidic platform represents a significant advancement, reducing background signals and simplifying the assay procedure without intricate procedure and pre-treatment. The NC membrane-based microfluidic device offers rapid, cost-effective, and highly sensitive detection of HNP 1, with a limit of detection of 0.5 mg L-1. The microfluidic device demonstrates exceptional performance, detecting up to four clinical samples in approximately 42 min on a single chip with 100 % accuracy, as confirmed by analysis of 12 clinical samples and comparison with "gold-standard". Moreover, the assay exhibits a wide dynamic range of 0.5-100 mg L-1, underscoring its potential as a powerful tool for PJI diagnosis in clinical settings.

SIGNIFICANCE

This work introduces a paper-based microfluidic system tailored for rapid HNP 1 detection using synovial fluid near joint region (and not serum via blood) for better diagnosis. The innovative paper-based aptamer-sandwich assay yields results within 42-min. Significantly, it boasts a wide dynamic range, detecting levels from an impressive 0.5 mg L-1, crucial in the 2.6 mg L-1 threshold region. This heightened sensitivity and expansive detection capability establish our assay as a leader in PJI diagnostics, promising unmatched precision and efficiency in clinical applications.

Novel diagnostic markers for periprosthetic joint infection: a systematic review

Background

Identifying novel biomarkers that are both specific and sensitive to periprosthetic joint infection (PJI) has the potential to improve diagnostic accuracy and ultimately enhance patient outcomes. Therefore, the aim of this systematic review is to identify and evaluate the effectiveness of novel biomarkers for the diagnosis of PJI.

Methods

We searched the MEDLINE, EMBASE, PubMed, and Cochrane Library databases from January 1, 2018, to September 30, 2022, using the search terms "periprosthetic joint infection," "prosthetic joint infection," or "periprosthetic infection" as the diagnosis of interest and the target index, combined with the term "marker." We excluded articles that mentioned established biomarkers such as CRP, ESR, Interleukin 6, Alpha defensin, PCT (procalcitonin), and LC (leucocyte cell count). We used the MSIS, ICM, or EBJS criteria for PJI as the reference standard during quality assessment.

Results

We collected 19 studies that analyzed fourteen different novel biomarkers. Proteins were the most commonly analyzed biomarkers (nine studies), followed by molecules (three studies), exosomes (two studies), DNA (two studies), interleukins (one study), and lysosomes (one study). Calprotectin was a frequently analyzed and promising marker. In the scenario where the threshold was set at ≥50-mg/mL, the calprotectin point-of-care (POC) performance showed a high sensitivity of 98.1% and a specificity of 95.7%.

Conclusion

None of the analyzed biomarkers demonstrated outstanding performance compared to the established parameters used for standardized treatment based on established PJI definitions. Further studies are needed to determine the benefit and usefulness of implementing new biomarkers in diagnostic PJI settings.

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.

The combined evaluation of fibrinogen and D-dimer levels are a helpful tool to exclude periprosthetic knee infection

This retrospective study was undertaken to (i) define the most appropriate thresholds for serum d-dimer and fibrinogen for differentiating aseptic failure from periprosthetic joint infection (PJI) and (ii) evaluate the predictive value of our d-dimer and fibrinogen threshold compared to previously proposed thresholds. This observational cohort study included consecutive patients who had undergone total knee arthroplasty (TKA) revision between January 2019 and December 2020. International Consensus Meeting diagnostic criteria were used to identify patients affected by the prosthetic infection. Receiver operating characteristic curve analyses assessed the predictive value of the parameters, and the areas under the curves were evaluated. We included 125 patients with a median age of 69 years (53-82) affected by painful TKA. Fifty-seven patients (47%) had PJI. Patients with PJI had higher median d-dimer, fibrinogen, ESR, and CRP when compared to patients believed to be free of PJI. The best threshold values for d-dimer and fibrinogen were 1063 ng/ml (sensitivity 0.72, specificity 0.74) and 420 mg/dl (sensitivity 0.67 and specificity 0.82), respectively. A d-dimer level >1063 ng/ml combined with a fibrinogen level >420 mg/dl had a sensitivity of 0.52, and a specificity of 0.90. We found that an increased d-dimer beyond 1063 ng/ml showed a better predictive value than the previously proposed threshold. The combined determination of d-dimer and fibrinogen displayed high specificity and should be considered an excellent tool to rule out an infection. The accuracy of the proposed cutoffs is more effective than previously reported.

The Diagnostic Accuracy of Neutrophils to Lymphocytes Ratio, Platelets to Lymphocytes Ratio, Monocytes to Lymphocytes Ratio, and Platelets to Mean Platelet Volume Ratio in Diagnosing Periprosthetic Knee Infections. Are Gender-Specific Cutoff Values Needed?

BACKGROUND

This study aimed to assess the most appropriate thresholds for neutrophils to lymphocytes ratio (NLR), platelets to lymphocytes ratio, monocytes to lymphocytes ratio (MLR), and platelets to mean platelet volume ratio in patients who had a suspected prosthetic knee infection. Furthermore, we evaluated the diagnostic accuracy of our proposed thresholds by men and women.

METHODS

A total of 261 consecutive patients affected by painful total knee arthroplasty were included. International Consensus Meeting diagnostic criteria were used to identify periprosthetic infections. Sensitivity, specificity, positive, and negative predictive values were calculated for each cutoff value obtained. The area under the receiver operating characteristic curve was evaluated.

RESULTS

NLR reported the best diagnostic accuracy. MLR and NLR reported higher area under the curves in men and women. We obtained an MLR value ≥0.30 (optimal cutoff value for men) and ≥0.17 (optimal cutoff value for women). In men, the sensitivity and the specificity were 0.71 and 0.77, respectively, versus 0.82 and 0.29, in women. For NLR, we obtained a value ≥2.52 (best cutoff value for men) and ≥2.46 (best cutoff value for women). These cutoffs reported a sensitivity and specificity of 0.71 and 0.88 versus 0.54 and 0.76 in men and women, respectively.

CONCLUSION

These biomarkers present a low diagnostic accuracy in periprosthetic joint infection detection. Men whose MLR and NLR were above cutoff values had a 77 and 88% probability of presenting a septic prosthetic failure. NLR of at least 2.46 was reasonably sensitive for women who have a periprosthetic knee infection.

LEVEL OF EVIDENCE

Diagnostic study, Level II.

Diagnostic Performance of Neutrophil to Lymphocyte Ratio, Monocyte to Lymphocyte Ratio, Platelet to Lymphocyte Ratio, and Platelet to Mean Platelet Volume Ratio in Periprosthetic Hip and Knee Infections: A Systematic Review and Meta-Analysis

The current literature on the diagnosis of periprosthetic joint infection provides controversial evidence on the diagnostic accuracy of MLR, NLR, PVR, and PLR. Therefore, this critical literature search and meta-analysis was aimed to summarize the diagnostic accuracy of these biomarkers for the diagnosis of hip and knee prosthetic infection. According to the PRISMA flowchart, we searched MEDLINE, Scopus, and Web of Science, for studies on these ratios for diagnosing PJI. Sensitivity, specificity, positive and negative likelihood ratio, diagnostic odds ratio, and AUC were analyzed. We included 11 articles in our meta-analysis, including 7537 patients who underwent total hip and knee arthroplasties; among these, 1974 (26%) patients reported a joint infection. The pooled sensitivity and specificity were 0.72 and 0.74, respectively, for NLR, 0.72 and 0.77 for PVR, and 0.77 and 0.75 for PLR. The sensitivity of MLR ranges from 0.54 to 0.81, while the specificity ranges from 0.78 to 0.81. Regarding the evaluation of AUCs, the best diagnostic performance was achieved by MLR (AUC = 0.77) followed by PLR (AUC = 0.75), NLR (AUC = 0.73), and PVR (AUC = 0.70). This meta-analysis demonstrates a fair diagnostic accuracy of these ratios, thus not being useful as a screening tool.

Quantitative alpha-defensin testing: Is synovial fluid dilution important?

BACKGROUND

Alpha-defensin has been widely studied for the diagnosis of periprosthetic joint infection (PJI). However, there is a lack of detailed information regarding the proper laboratory technique of the enzyme-linked immunosorbent assay (ELISA) method, such as sample dilution.

AIM

To assess the influence of dilution in the synovial fluid during ELISA for the diagnosis of knee PJI; and determine which dilution presents a better performance.

METHODS

Forty samples of synovial fluid from arthroplasty knees were included, 17 in the infected group and 23 in the aseptic group, according to Musculoskeletal Infection Society criteria. Initially, five synovial fluid samples from each group were assessed for quantitative analysis of alpha-defensin using ELISA. Different dilution ratios (1:10, 1:100, 1:500, 1:1000 and 1:5000) were tested based on the predetermined cutoff value of 5.2 mg/L. The dilutions that performed better were used to compare the results of all samples.

RESULTS

For infected cases, a gradual increase in the dilution of synovial fluid samples led to an equivalent increase in alpha-defensin level. The same was not observed in the aseptic cases. Both 1:1000 and 1:5000 dilutions presented satisfactory results to differentiate infected and aseptic cases. Further analyses were performed using 1:1000 and 1:5000 for all 40 samples. The 1:1000 dilution resulted in a sensitivity of 88.2% (95%CI, 66%-98%) and specificity of 95.7% (95%CI, 79%-99%), whereas the 1:5000 dilution presented a sensitivity of 94.1% (95%CI, 73%-99%) and a specificity of 100% (95%CI, 86%-100%).

CONCLUSION

The synovial fluid dilution had an important influence on the alpha-defensin ELISA results. Dilutions of 1:5000 showed the best performance for the diagnosis of knee PJI. The results of this study set the basis for a more reliable and reproducible alpha-defensin ELISA during the investigation of PJI, contributing to the expansion of this technique in different treatment centers worldwide.

Interventions for Early-Stage Pericoronitis: Systematic Review of Randomized Clinical Trials

Background: To investigate the efficacy and safety of interventions for early stage pericoronitis. Methods: We searched for randomized controlled trials (RCTs) in databases from inception to July 2020, without language restriction. RCTs assessing adolescents and adults were included. Results: Seven RCT with clinical diversity were included, so, it was not possible to conduct meta-analyses. Individual study data showed an improvement in oral health quality of life in favor of topical benzydamine versus diclofenac capsule (Mean difference (MD) −1.10, 95% Confidence interval (CI) −1.85 to −0.35), and no difference between topical benzydamine and flurbiprofen capsule (MD −0.55 95% CI −1.18 to 0.0). There was no difference between diclofenac and flurbiprofen capsules (MD 0.55, 95% CI −0.29 to 1.39). An imprecise estimate of effects was found for all outcomes, considering (i) oral versus topic pharmacological treatment, (ii) different oral pharmacological treatments, (iii) pharmacological treatment associated with laser versus placebo laser, (iv) pharmacological treatment associated with different mouthwashes, and (v) conventional treatment associated to antimicrobial photodynamic therapy versus conventional treatment, with low to very low certainty of evidence. Conclusions: Until future well-designed studies can be conducted, the clinical decision for early stage pericoronitis should be guided by individual characteristics, settings and financial aspects.

Synovial calprotectin for the diagnosis of periprosthetic joint infection: a diagnostic meta-analysis

Background

Periprosthetic joint infections (PJI) are a rare but severe complication of total joint arthroplasty (TJA). However, the diagnosis of PJI remains difficult. It is one of the research that focuses about diagnosis for PJI for majority researchers to discover a novel biomarker. This meta-analysis tried to evaluate diagnostic value of synovial calprotectin for PJI.

Methods

This meta-analysis search of the literature was conducted in PubMed, EMBASE, Web of Science, and the Cochrane Library. Literature quality was appraised using Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) based on RevMan (version 5.3). The diagnostic value of calprotectin for PJI was evaluated by calculating sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), diagnostic score and area under SROC (AUC) based on the Stata version 14.0 software. We conduct subgroup analysis according to the study design, cutoff values, the country of study, and gold standard.

Results

Seven studies were included in this meta-analysis. The pooled sensitivity of synovial calprotectin for the diagnosis of PJI was 0.94 (95% CI, 0.87–0.98), and the specificity was 0.93 (95% CI, 0.87–0.96). The pooled AUC, PLR, and NLR for synovial calprotectin were 0.98 (95% CI, 0.96–0.99), 13.65 (95% CI, 6.89–27.07), and 0.06 (95% CI, 0.02–0.15), respectively. The pooled diagnostic score and DOR were 5.4 (95% CI, 3.96–6.85) and 222.32 (95% CI, 52.52–941.12), respectively.

Conclusion

In summary, this meta-analysis indicates that synovial calprotectin is a promising biomarker of assistant diagnosis for PJI, as well as recommended test for excluding diagnostic tool.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02746-2.

D-dimer for diagnosis of periprosthetic joint infection: A meta-analysis

BACKGROUND

The D-dimer test is easily available to detect periprosthetic joint infection (PJI). This study aimed to estimate the diagnostic accuracy of the D-dimer test in PJI diagnosis and identify possible independent factors affecting the diagnostic value of this test.

METHODS

MEDLINE and EMBASE databases identified literature until February 2020 that utilized the D-dimer test for PJI diagnosis. The pooled sensitivity, specificity, area under the curve (AUC), diagnostic odds ratio (DOR), positive likelihood ratio (PLR), and negative likelihood ratio (NLR) were calculated to evaluate the diagnostic accuracy of the D-dimer test. Meta-regression and subgroup analyses were performed to assess potential heterogeneity.

RESULTS

The databases identified 243 records, and eight studies were included in the final analysis. The pooled sensitivity and specificity of the D-dimer test for PJI diagnosis were 0.78 (95% confidence interval [CI], 0.69-0.84) and 0.74 (95% CI, 0.85-0.99), respectively. The AUCs and DORs of the D-dimer test were 0.83 (95% CI, 0.79-0.86) and 10 (95% CI, 4-24), respectively. The PLR and NLR of the D-dimer test for PJI detection were 3.0 (95% CI, 1.9-4.8) and 0.30 (95% CI, 0.20-0.47), respectively. The results of the meta-regression and subgroup analyses indicated that studies that excluded patients with hypercoagulation disorder had higher sensitivity (0.85 vs 0.86) and specificity (0.83 vs 0.62). The sensitivity of the D-dimer test also improved in studies that excluded patients with inflammatory arthritis (0.81 vs 0.75).

CONCLUSION

The D-dimer test is a practical method for PJI diagnosis, especially in patients without history of hypercoagulation disorder and inflammatory arthritis.

Accuracy and Cost-Effectivenss of a Novel Method for Alpha Defensins Measurement in the Diagnosis of Periprosthetic Joint Infections

BACKGROUND

Two methods for detecting synovial fluids alpha defensins are available: the enzyme-linked immunosorbent assay and the lateral flow test. For both, the proper role and accuracy remain uncertain. The purpose of this study was to assess the accuracy of the matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) for alpha defensin detection in synovial fluids of patients with total knee arthroplasty/total hip arthroplasty failures. The hypothesis was that the alpha defensin measurement through MALDI-TOF MS assay could be a high sensitive and specific test for periprosthetic joint infections (PJI) diagnosis as compared with Musculoskeletal Infection Society (MSIS) criteria.

METHODS

The study included 138 patients. The 2018 MSIS criteria were used to diagnose PJIs. Synovial fluids were assessed for routinely synovial fluid tests and alpha defensin measurement through MALDI-TOF MS. Sensitivity, specificity, overall diagnostic accuracy, positive and negative predictive values, receiver operator curves, and area under the curve were calculated.

RESULTS

As per the 2018 MSIS criteria, 59 PJIs (43%) and 79 aseptic failures (57%) were diagnosed. The MALDI-TOF MS assay showed an overall accuracy of 94.9%. The sensitivity was 93%, the specificity was 96%, the positive predictive value was 95%, and the negative predictive value was 95%. Receiver operator curves analysis demonstrates an area under the curve of 0.95 (P < .001).

CONCLUSION

The MALDI-TOF MS assay showed high sensitivity and specificity for alpha defensin detection in case of total knee arthroplasty/total hip arthroplasty failures. The advantages of the technology, such as the few milliliters of sample needed, the rapidity of obtaining results, and the cost-effectiveness of the procedure could make the MALDI-TOF MS alpha defensin assay a useful and widespread test in clinical practice.

Performance of alpha-defensin lateral flow test after synovial fluid centrifugation for diagnosis of periprosthetic knee infection

BACKGROUND

The quantitative alpha-defensin enzyme-linked immunosorbent assay (ELISA) demands a prior synovial fluid centrifugation, whereas this processing is not routinely required prior to the alpha-defensin lateral flow test.

AIM

To evaluate whether a prior synovial fluid centrifugation could lead the lateral flow performance to achieve comparable results to ELISA during periprosthetic joint infection (PJI) diagnosis.

METHODS

Fifty-three cases were included in this study: 22 classified as PJI and 31 classified as aseptic cases, according to Musculoskeletal Infection Society 2013 criteria. Synovial fluid samples were submitted to centrifugation, and the supernatant was evaluated by ELISA and lateral flow tests. The sensitivity (SE), specificity (SP) and accuracy of each method were calculated as well as the agreement between those two methods.

RESULTS

In all of the 31 samples from aseptic patients, alpha-defensin ELISA and lateral flow tests showed negative results for infection. Regarding the 22 infected patients, the lateral flow test was positive in 19 cases (86.4%) and the ELISA was positive in 21 (95.5%). Sensibility, SP and accuracy were, respectively, 86.4% (95%CI: 65.1%-97.1%), 100% (95%CI: 88.8%-100%) and 93.2% (95%CI: 82.8%-98.3%) for the lateral flow test and 95.5% (95%CI: 77.2%-99.9%), 100% (95%CI: 88.8%-100%) and 98.1% (95%CI: 89.9%-100%) for ELISA. An agreement of 96.2% between those methods were observed. No statistical difference was found between them (P = 0.48).

CONCLUSION

Alpha-defensin lateral flow test showed high SE, SP and accuracy after a prior synovial fluid centrifugation, achieving comparable results to ELISA. Considering the lower complexity of the lateral flow and its equivalent performance obtained in this condition, a prior centrifugation might be added as a valuable step to enhance the PJI diagnosis.

Comparative diagnostic accuracy of respective nuclear imaging for suspected fracture-related infection: a systematic review and Bayesian network meta-analysis

BACKGROUND

The aim of this study was to compare the accuracy of available nuclear imaging modalities in the diagnosis of suspected fracture-related infection (FRI).

METHODS

We conducted a comprehensive literature search of PubMed, EMBASE and the Cochrane Library to retrieve diagnostic accuracy studies in which FRI was investigated using different nuclear imaging modalities. The pooled sensitivity, specificity, likelihood ratios and diagnostic odds ratios were constructed using the bivariate meta-analysis framework, while the superior index was pooled using Bayesian network meta-analysis.

RESULTS

22 eligible studies (1,565 patients) were included in the quantitative analysis. A broad overlapping confidence interval (CI) of pooled sensitivity was observed among bone scintigraphy (0.94; 95% CI 0.85-0.98), ¹⁸F-FDG PET and PET/CT (0.91; 95% CI 0.85-0.94) and leukocyte scintigraphy (0.86; 95% CI 0.53-0.97). Bone scintigraphy (0.34; 95% CI 0.08-0.75) seemed to be less specific than all the other modalities, while leukocyte scintigraphy (0.96, 95% CI 0.92-0.98) was notably more specific than ¹⁸F-FDG PET and PET/CT (0.78; 95% CI 0.69-0.85). Based on the superiority index, ¹⁸F-FDG PET/CT (3.78; 95% CI 0.14-11.00), ¹⁸F-FDG PET (2.98; 95% CI 0.14-9.00) and leukocyte scintigraphy (1.51; 95% CI 0.11-7.00) all achieved high accuracy in detecting FRI.

CONCLUSION

Bone scintigraphy is a highly sensitive nuclear imaging technique but lacks the specificity needed to unequivocally differentiate among various conditions suspected to be FRI. Leukocyte scintigraphy, ¹⁸F-FDG PET/CT and PET all present good satisfactory accuracy for the diagnosis of FRI, but their costs should be further reduced to promote their wide application.

Synovial fluid α defensin has comparable accuracy to synovial fluid white blood cell count and polymorphonuclear percentage for periprosthetic joint infection diagnosis

AIMS

The aim of this study was to determine the diagnostic accuracy of α defensin (AD) lateral flow assay (LFA) and enzyme-linked immunosorbent assay (ELISA) tests for periprosthetic joint infection (PJI) in comparison to conventional synovial white blood cell (WBC) count and polymorphonuclear neutrophil percentage (PMN%) analysis.

METHODS

Patients undergoing joint aspiration for evaluation of pain after total knee arthroplasty (TKA) or total hip arthroplasty (THA) were considered for inclusion. Synovial fluids from 99 patients (25 THA and 74 TKA) were analyzed by WBC count and PMN% analysis, AD LFA, and AD ELISA. WBC and PMN% cutoffs of ≥ 1,700 cells/mm³ and ≥ 65% for TKA and ≥ 3,000 cells/mm³ and ≥ 80% for THA were used, respectively. A panel of three physicians, all with expertise in orthopaedic infections and who were blinded to the results of AD tests, independently reviewed patient data to diagnose subjects as with or without PJI. Consensus PJI classification was used as the reference standard to evaluate test performances. Results were compared using McNemar's test and area under the receiver operating characteristic curve (AUC) analysis.

RESULTS

Expert consensus classified 18 arthroplasies as having failed due to PJI and 81 due to aseptic failure. Using these classifications, the calculated sensitivity and specificity of AD LFA was 83.3% (95% confidence interval (CI) 58.6 to 96.4) and 93.8% (95% CI 86.2 to 98.0), respectively. Sensitivity and specificity of AD ELISA was 83.3% (95% CI 58.6 to 96.4) and 96.3% (95% CI 89.6 to 99.2), respectively. There was no statistically significant difference between sensitivity (p = 1.000) or specificity (p = 0.157) of the two AD assays. AUC for AD LFA was 0.891. In comparison, AUC for synovial WBC count, PMN%, and the combination of the two values was 0.821 (sensitivity p = 1.000, specificity p < 0.001), 0.886 (sensitivity p = 0.317, specificity p = 0.011), and 0.926 (sensitivity p = 0.317, specificity p = 0.317), respectively.

CONCLUSION

The diagnostic accuracy of synovial AD for PJI diagnosis is comparable and not statistically superior to that of synovial WBC count plus PMN% combined. Cite this article: Bone Joint J 2021;103-B(6):1119-1126.

The role of D-dimer in periprosthetic joint infection: a systematic review and meta-analysis

OBJECTIVES

The current literature on diagnosis of periprosthetic joint infection (PJI) provides controversial evidence on the diagnostic accuracy of D-dimer. Therefore, this critical literature search and meta-analysis was aimed to summarize the diagnostic accuracy of D-dimer for diagnosing PJI.

CONTENT

We searched MEDLINE, Scopus, and Web of Science, for studies on D-dimer for diagnosing PJI, according to the PRISMA flowchart. QUADAS was used for assessing study quality. Sensitivity, specificity, positive (PLR) and negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were analyzed using bivariate diagnostic random-effects model. The area under the receiver-operating curve (AUC-ROC) was calculated. Subgroup analysis and univariate meta-regression were carried out for detecting potential sources of heterogeneity.

SUMMARY

We included 12 articles, totaling 1,818 patients (539 with PJI). The pooled sensitivity and specificity of D-dimer for diagnosing PJI were 0.739 (95% CI: 0.616-0.833) and 0.785 (95% CI: 0.679-0.863). The pooled PLR, NLR, DOR were 3.359 (95% CI, 2.340-4.821), 0.295 (95% CI, 0.180-0.484), and 11.787 (95% CI, 5.785-24.018). The cumulative ROC plot displayed an AUC of 0.688 (95% CI, 0.663-0.713; p<0.001). No threshold effects could be observed. The type of blood sample was identified as possible source of heterogeneity for DOR (p=0.01).

OUTLOOK

Evidence emerged from this meta-analysis suggests that D-dimer displays sufficient diagnostic accuracy to rule out PJI. The type of blood sample (plasma vs. serum) and the study design could influence the results in terms of DOR and sensitivity. However, further perspective studies would be needed to validate its potential diagnostic usefulness.

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.

Validation of the Alpha Defensin Lateral Flow Test for Periprosthetic Joint Infection

BACKGROUND

The synovial fluid test for alpha defensin has been reported to have an excellent performance in diagnosing periprosthetic joint infection (PJI). The purpose of this study was to evaluate the performance of the lateral flow test for synovial fluid alpha defensin by using the methods of a formal diagnostic accuracy study and to compare its performance with that of the laboratory-based alpha defensin test for PJI.

METHODS

We conducted a diagnostic accuracy study of the index lateral flow immunoassay for synovial fluid alpha defensin relative to the reference 2013 Musculoskeletal Infection Society (MSIS) multicriteria definition of PJI. The study included a prospective multicenter cohort of outpatients with a failed hip or knee arthroplasty and a supplemental control cohort of fresh synovial fluid specimens submitted by physicians for diagnostic PJI testing.

RESULTS

Among 57 patients with PJI and 248 patients without PJI in the overall prospective patient cohort, the sensitivity and specificity of the alpha defensin lateral flow test were 89.5% (95% confidence interval [CI]: 78.5% to 96.0%) and 94.8% (95% CI: 91.2% to 97.2%), respectively. The sensitivity increased to 94.3% (95% CI: 84.3% to 98.8%) after exclusion of 17 patients with grossly bloody aspirates (>1 million red blood cells/µL). Among the supplemental control cohort of fresh synovial fluid samples, including 65 samples from patients with PJI and 397 from patients without PJI, the sensitivity and specificity of the alpha defensin lateral flow test were 98.5% (95% CI: 91.7% to 100.0%) and 98.2% (95% CI: 96.4% to 99.3%), respectively. A comparison of the sensitivity and specificity of the alpha defensin lateral flow test with those of the alpha defensin enzyme-linked immunosorbent assay (ELISA) in the combined cohort did not demonstrate a significant difference in sensitivity (94.3% [95% CI: 88.5% to 97.7%] compared with 93.0% [95% CI: 87.1% to 96.7%]) or specificity (96.9% [95% CI: 95.3% to 98.1%] compared with 97.8% [95% CI: 96.4% to 98.8%]) (both p > 0.05).

CONCLUSIONS

The results of this study demonstrate the solid diagnostic performance of the alpha defensin test and have resulted in the U.S. Food and Drug Administration (FDA) authorization of the lateral-flow test with an intended use as an aid in the clinical diagnosis of PJI.

LEVEL OF EVIDENCE

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

Analysis of synovial biomarkers with a multiplex protein microarray in patients with PJI undergoing revision arthroplasty of the hip or knee joint

INTRODUCTION

Diagnosing a (low-grade) periprosthetic joint infection (PJI) after hip or knee arthroplasty remains a diagnostic challenge. The aim of this study was to evaluate the utility of using a novel multiplex protein microarray system for synovial biomarkers in determining PJI in patients undergoing revision knee or hip arthroplasty.

MATERIALS AND METHODS

The individual synovial fluid levels of 12 cytokines (IL-1b, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-17, GM-CSF, TNF-α, and INF-γ) were analysed with a novel multiplex protein microarray system in 32 patients undergoing revision hip (n = 22) or knee (n = 10) arthroplasty. Cases were classified into septic and aseptic groups on basis of pre- and interoperative findings: [PJI (n = 14) vs. non-PJI (n = 18)]. Receiver operator characteristic (ROC) curves were calculated to assess the discriminatory strength of the individual parameters. A multiple regression model was used to determine the utility of using a combination of the tested cytokines to determine the infection status.

RESULTS

The levels of all of the evaluated cytokines were significantly elevated in the PJI-group. Best sensitivity and specificity were found for IL-6, followed by IL-1b, IL-10, and IL-17. The multiple regression models revealed a combination of IL-2, IL-4, IL-5, IL6, lL-12, and GM-CSF to be associated with the best sensitivity (100%) and specificity (88.9%) for a cut-off value of 0.41, with a likelihood ratio of 9.0.

CONCLUSION

Analysis of individual synovial fluid cytokine levels showed both high sensitivity and high specificity in diagnosing PJI. A combined model using several cytokines showed even higher sensitivity and specificity in diagnosing PJI and could thus be a useful predictive tool to determine the probability of PJI in patients with a painful prosthesis.

LEVEL OF EVIDENCE

Diagnostic IV.

A profile on the Synovasure alpha defensin test for the detection of periprosthetic infections

INTRODUCTION

Clinicians have waited a long time for a 'universal' marker that may help them distinguish infected from non-infected total joint arthroplasties when doubts persist after using classical clinical and biological signs of infection. In recent years, synovial fluid biomarkers including leukocyte esterase, alpha-defensins, and CRP have shown promising results for the diagnosis of periprosthetic joint infections (PJIs).

AREAS COVERED

This review provides an overview of the rational and the use of the Synovasure® alpha-defensin tests in patients with a suspicion of PJI. Using a systematic investigation by keywords, we looked for all citations (and the citations to these citations) of the selected papers.

EXPERT OPINION

The Synovasure® alpha-defensin tests demonstrate high potential for the diagnosis of PJIs. However, the data currently available also show that the universal marker of infection in the settings of PJIs is still to be discovered.

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.

The cellular basis of organ failure in sepsis-signaling during damage and repair processes

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. This definition, updated in 2016, shifted the conceptual focus from exclusive attention to the systemic inflammatory response toward the multifactorial tissue damage that occurs during the progression of infection to sepsis and shock. Whereas targeting the inflammatory host response to infection did not translate into improved clinical management of sepsis, recent findings might shed new light on the maladaptive host–pathogen interaction in sepsis and pave the way for “theranostic” interventions. In addition to the well-known resistance responses of the immune system that result in pathogen clearance, “disease tolerance” has recently been acknowledged as a coping mechanism of presumably equal importance. We propose that both defense mechanisms, “resistance” and “disease tolerance”, can get out of control in sepsis. Whereas excessive activation of resistance pathways propagates tissue damage via immunopathology, an inappropriate “tolerance” might entail immunoparalysis accompanied by fulminant, recurrent or persisting infection. The review introduces key signaling processes involved in infection-induced “resistance” and “tolerance”. We propose that elaboration of these signaling pathways allows novel insights into sepsis-associated tissue damage and repair processes. Moreover theranostic opportunities for the specific treatment of sepsis-related hyperinflammation or immunoparalysis will be introduced. Agents specifically affecting either hyperinflammation or immunoparalysis in the course of sepsis might add to the therapeutic toolbox of personalized care in the field of organ dysfunction caused by infection. (This article is freely available.)