LTF, PRTN3, and MNDA in Synovial Fluid as Promising Biomarkers for Periprosthetic Joint Infection: Identification by Quadrupole Orbital-Trap Mass Spectrometry

Diagnostics in Late Periprosthetic Infections-Challenges and Solutions

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

Differences in the Synovial Fluid Proteome of Septic and Aseptic Implant Failure

Implant loosening is a severe complication after total joint replacement. Here, differential diagnosis between septic and aseptic cases is crucial for further surgical treatment, but low-grade periprosthetic joint infections (PJIs) in particular remain a challenge. In this study, we analyzed the synovial fluid proteome of 21 patients undergoing revision surgery for septic (eight cases) or aseptic (thirteen cases) implant failure using LC-MS/MS to identify potential new biomarkers as future diagnostic tools. Staphylococci were found in four cases, Streptococci in two cases, Serratia marcescens and Cutibacterium acnes in one case. Proteomic analysis of the synovial fluid resulted in the identification of 515 different proteins based on at least two peptides. A statistical comparison revealed 37 differentially abundant proteins (p < 0.05), of which 17 proteins (46%) showed a higher abundance in the septic group. The proteins with the highest fold change included the known marker proteins c-reactive protein (7.57-fold) and the calprotectin components protein S100-A8 (4.41-fold) and protein S100-A9 (3.1-fold). However, the protein with the highest fold change was leucine-rich alpha-2-glycoprotein 1 (LRG1) (9.07-fold), a currently discussed new biomarker for inflammatory diseases. Elevated LRG1 levels could facilitate the diagnosis of PJI in the future, but their significance needs to be further investigated.

Synovial Fluid Biomarkers for the Diagnosis of Periprosthetic Joint Infection-A Systematic Review and Meta-Analysis of Their Diagnostic Accuracy According to Different Definitions

BACKGROUND

Different synovial fluid biomarkers have emerged to improve periprosthetic joint infection (PJI) diagnosis. The goals of this paper were (i) to assess their diagnostic accuracy and (ii) to evaluate their performance according to different PJI definitions.

METHODS

A systematic review and meta-analysis was performed using studies that reported diagnostic accuracy of synovial fluid biomarkers using validated PJI definitions published from 2010 to March 2022. A database search was performed through PubMed, Ovid MEDLINE, Central, and Embase. The search identified 43 different biomarkers with four being the more commonly studied, with 75 papers overall: alpha-defensin; leukocyte esterase; synovial fluid C-reactive protein; and calprotectin.

RESULTS

Overall accuracy was higher for calprotectin, followed by alpha-defensin, leukocyte esterase, and synovial fluid C-reactive protein with sensitivities of 78 to 92% and specificities of 90 to 95%. Their diagnostic performance was different according to which definition was adopted as the reference. Specificity was consistently high across definitions for all four biomarkers. Sensitivity varied the most with lower values for the more sensitive European Bone and Joint Infection Society or Infectious Diseases Society of America definitions with higher values for the Musculoskeletal Infection Society definition. The International Consensus Meeting 2018 definition showed intermediate values.

CONCLUSION

All evaluated biomarkers had good specificity and sensitivity, making their use acceptable in the diagnosis of PJI. Biomarkers perform differently according to the selected PJI definitions.

Joint aspiration for diagnosis of chronic periprosthetic joint infection: when, how, and what tests?

Diagnosing chronic periprosthetic joint infection (PJI) requires clinical suspicion in combination with both serological and synovial fluid tests, the results of which are generally applied to validated scoring systems or consensus definitions for PJI. As no single "gold standard" test exists, the diagnosis becomes challenging, especially in the setting of negative cultures or equivocal test results. This review aims to address the workup of chronic PJI and considerations for clinical evaluation to guide treatment. Following aspiration of the joint in question, a multitude of tests has been developed in an attempt to assist with diagnosis, including cell synovial white blood cell count, gram stain, cultures, leukocyte esterase, alpha-defensin, synovial C-reactive protein, multiplex polymerase chain reaction, next-generation sequencing, and interleukins. Each test has advantages and disadvantages and should be used in conjunction with the overall clinical picture to guide further clinical evaluation and treatment in this complex patient population.

Mass spectrometry-based proteomic profiling of sonicate fluid differentiates Staphylococcus aureus periprosthetic joint infection from non-infectious failure: A pilot study

PURPOSE

This pilot study aimed to use proteomic profiling of sonicate fluid samples to compare host response during Staphylococcus aureus-associated periprosthetic joint infection (PJI) and non-infected arthroplasty failure (NIAF) and identify potential novel biomarkers differentiating the two.

EXPERIMENTAL DESIGN

In this pilot study, eight sonicate fluid samples (four from NIAF and four from S. aureus PJI) were studied. Samples were reduced, alkylated, and trypsinized overnight, followed by analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) on a high-resolution Orbitrap Eclipse mass spectrometer. MaxQuant software suite was used for protein identification, filtering, and label-free quantitation.

RESULTS

Principal component analysis of the identified proteins clearly separated S. aureus PJI and NIAF samples. Overall, 810 proteins were identified based on their detection in at least three out of four samples from each group; 35 statistically significant differentially abundant proteins (DAPs) were found (two-sample t-test p-values ≤0.05 and log2 fold-change values ≥2 or ≤-2). Gene ontology pathway analysis found that microbial defense responses, specifically those related to neutrophil activation, to be increased in S. aureus PJI compared to NIAF samples.

CONCLUSION AND CLINICAL RELEVANCE

Proteomic profiling of sonicate fluid using LC-MS/MS differentiated S. aureus PJI and NIAF in this pilot study. Further work is needed using a larger sample size and including non-S. aureus PJI and a diversty of NIAF-types.

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.

Detection of synovial fluid LTF and S100A8 by chemiluminescence immunoassay for the diagnosis of periprosthetic joint infection

BACKGROUND AND AIMS

Synovial fluid lactoferrin (LTF) and S100 calcium-binding protein A8 (S100A8) have been considered as potential biomarkers for the diagnosis of periprosthetic joint infection (PJI) through our previous research. However, the detection methods of these two proteins are still immature, so a rapid, accurate and cost-effective testing method is warranted.

MATERIALS AND METHODS

We developed chemiluminescent immunoassays (CLIA) for the automated detection of synovial fluid LTF and S100A8 and assessed the analytical performance for these two methods. In addition, we recruited 86 patients who were suspected of PJI after total joint replacement (TJA) and examined their synovial fluid using CLIA to explore the clinical application value of these methods and the diagnostic efficiency of synovial fluid LTF and S100A8 for PJI.

RESULTS

Our established CLIA methods have a wide linear range of 20-10000 ng/mL for LTF detection system and 5-5000 ng/mL for S100A8 detection system. Performance parameters such as precision, specificity, and recovery rate can meet the industry standards. Then, the established methods were used to detect LTF and S100A8 in synovial fluid samples, which showed excellent diagnostic efficiency for PJI, and the areas under ROC curve (AUC) were 0.954 (95% CI: 0.909-0.999) and 0.958 (95% CI: 0.918-0.997), respectively.

CONCLUSION

Our established CLIA methods have the advantages of automation, high throughput, low price, and is expected to be widely popularized in clinical applications. Synovial fluid LTF and S100A8 detected through CLIA had efficient diagnostic potentiality for predicting and diagnosing PJI.

Identification of PRTN3 as a novel biomarker for the diagnosis of early gastric cance

Gastric cancer (GC) remains one of the most common types of cancer worldwide and has a high mortality rate. However, tools for the early detection of gastric cancer are still lacking. Isobaric tagging for relative and absolute quantitation (iTRAQ) proteomic assays were conducted to identify and quantify the differentially expressed proteins (DEPs) in the gastric mucosal tissues of GC patients at different stages. Bioinformatics analysis was used to identify the pathways enriched among the DEPs and candidate marker proteins. The expression levels and distribution of candidate proteins were confirmed by parallel reaction monitoring (PRM) analysis. In this study, by using the iTRAQ quantitative proteomic strategy, we identified 727 and 502 DEPs that were upregulated in EGC vs. PGC and EGC vs. NGC, respectively. These DEPs were mainly involved in the innate immune response and RNA binding. PRTN3 was identified as a marker of early gastric cancer by Gene Ontology enrichment analysis. Furthermore, the PRM assay confirmed the significant overexpression of PRTN3 in EGC gastric mucosa compared to PGC and NGC mucosa. Our data demonstrated that PRTN3 in the gastric mucosa could be used as a novel biomarker to identify patients with early gastric cancer via endoscopy. SIGNIFICANCE: Gastric cancer remains one of the most common types of cancer worldwide and has a high mortality rate. Patients with progressive gastric cancer and gastroesophageal junction cancer have a poor prognosis, with a 5-year relative survival rate of 6%. Therefore, early detection and diagnosis of gastric cancer is a key step toward improving the survival rate. The present study identified PRTN3 as a marker of early gastric cancer by an iTRAQ quantitative proteomic strategy. The PRM assay confirmed the significant overexpression of PRTN3 in EGC gastric mucosa compared to PGC and NGC mucosa. This study discovered that PRTN3 in the gastric mucosa could be used as a novel biomarker to identify patients with early gastric cancer via endoscopy.

Quantitative proteomic analysis of human serum using tandem mass tags to predict cardiovascular risks in patients with psoriasis

Although biomarker candidates associated with psoriasis have been suggested, those for predicting the risk of cardiovascular disease (CVD) early in patients with psoriasis are lacking. We aimed to identify candidate biomarkers that can predict the occurrence of CVD in psoriasis patients. We pursued quantitative proteomic analysis of serum samples composed of three groups: psoriasis patients with and those without CVD risk factors, and healthy controls. Age/Sex-matched serum samples were selected and labeled with 16-plex tandem mass tag (TMT) and analyzed using liquid chromatography-mass spectrometry and subsequent verification with ELISA. Of the 184 proteins that showed statistical significance (P-value < 0.05) among the three groups according to TMT-based quantitative analysis, 98 proteins showed significant differences (> 2.0-fold) between the psoriasis groups with and without CVD risk factors. Verification by ELISA revealed that caldesmon (CALD1), myeloid cell nuclear differentiation antigen (MNDA), and zyxin (ZYX) levels were significantly increased in the psoriasis group with CVD risk factors. Further network analysis identified pathways including integrin signaling, which could be related to platelet aggregation, and actin cytoskeleton signaling. Three novel candidates (MNDA, ZYX, and CALD1) could be potential biomarkers for predicting CVD risks in psoriasis patients. We expect these biomarker candidates can be used to predict CVD risk in psoriasis patients in clinical settings although further studies including large validation are needed.

Integrated Analysis of Metabolomics and Lipidomics in Plasma of T2DM Patients with Diabetic Retinopathy

Diabetic retinopathy (DR) is a major cause of blindness worldwide and may be non-proliferative (NPDR) or proliferative (PDR). To Investig.gate the metabolomic and lipidomic characteristics of plasma in DR patients, plasma samples were collected from patients with type 2 diabetes mellitus (DR group) with PDR (n = 27), NPDR (n = 18), or no retinopathy (controls, n = 21). Levels of 54 and 41 metabolites were significantly altered in the plasma of DR patients under positive and negative ion modes, respectively. By subgroup analysis, 74 and 29 significantly changed plasma metabolites were detected in PDR patients compared with NPDR patients under positive and negative ion modes, respectively. KEGG analysis indicated that pathways such as biosynthesis of amino acids and neuroactive ligand-receptor interaction were among the most enriched pathways in altered metabolites in the DR group and PDR subgroup. Moreover, a total of 26 and 41 lipids were significantly changed in the DR group and the PDR subgroup, respectively. The panel using the 29-item index could discriminate effectively between diabetic patients with and without retinopathy, and the panel of 22 items showed effective discrimination between PDR and NPDR. These results provide a basis for further research into the therapeutic targets associated with these metabolite and lipid alterations.

A 92 protein inflammation panel performed on sonicate fluid differentiates periprosthetic joint infection from non-infectious causes of arthroplasty failure

Periprosthetic joint infection (PJI) is a major complication of total joint arthroplasty, typically necessitating surgical intervention and prolonged antimicrobial therapy. Currently, there is no perfect assay for PJI diagnosis. Proteomic profiling of sonicate fluid has the potential to differentiate PJI from non-infectious arthroplasty failure (NIAF) and possibly clinical subsets of PJI and/or NIAF. In this study, 200 sonicate fluid samples, including 90 from subjects with NIAF (23 aseptic loosening, 35 instability, 10 stiffness, five osteolysis, and 17 other) and 110 from subjects with PJI (40 Staphylococcus aureus, 40 Staphylococcus epidermidis, 10 Staphylococcus lugdunensis, 10 Streptococcus agalactiae, and 10 Enterococcus faecalis) were analyzed by proximity extension assay using the 92 protein Inflammation Panel from Olink Proteomics. Thirty-seven of the 92 proteins examined, including CCL20, OSM, EN-RAGE, IL8, and IL6, were differentially expressed in PJI versus NIAF sonicate fluid samples, with none of the 92 proteins differentially expressed between staphylococcal versus non-staphylococcal PJI, nor between the different types of NIAF studied. IL-17A and CCL11 were differentially expressed between PJI caused by different bacterial species, with IL-17A detected at higher levels in S. aureus compared to S. epidermidis and S. lugdunensis PJI, and CCL11 detected at higher levels in S. epidermidis compared to S. aureus and S. agalactiae PJI. Receiver operative characteristic curve analysis identified individual proteins and combinations of proteins that could differentiate PJI from NIAF. Overall, proteomic profiling using this small protein panel was able to differentiate between PJI and NIAF sonicate samples and provide a better understanding of the immune response during arthroplasty failure.

Complement factor D as a predictor of Achilles tendon healing and long-term patient outcomes

Dense connective tissue healing, such as tendon, is protracted leading to highly variable and unsatisfactory patient outcomes. Biomarkers prognostic of long-term clinical outcomes is, however, unknown. The present study was designed to investigate the proteomic profile of healing, identify potential biomarkers, and assess their association with the patient's long-term outcomes after ATR. Quantitative mass spectrometry analysis demonstrated 1423 proteins in healing and contralateral healthy Achilles tendons of 28 ATR patients. Comparing healing at 2 weeks and healthy protein profiles, we identified 821 overlapping, 390 upregulated, and 17 downregulated proteins. Upregulated proteins are related mainly to extracellular matrix organization and metabolism, while downregulated pathways were associated with exocytosis in immune modulation and thrombosis formation. Further proteomic profiling in relation to validated patient outcomes revealed the downregulated pro-inflammatory complement factor D (CFD) as the most reliable predictive biomarker of successful tendon healing. Our finding showed a comprehensive proteomic landscape and bioinformatics on human connective tissue, indicating subtype-specific and shared biological processes and proteins in healing and healthy Achilles tendons, as well as in tendons related to good and poor patient outcomes. Inflammatory protein CFD and serpin family B member 1 were finally identified as potential predictive biomarkers of effective healing outcomes when combined the proteomic profiles with a validated clinical database. Following the future elucidation of the mechanisms associated with the identified biomarkers as predictors of good outcomes, our findings could lead to improved prognostic accuracy and development of targeted treatments, thus improving the long-term healing outcomes for all patients.

Activated polymorphonuclear derived extracellular vesicles are potential biomarkers of periprosthetic joint infection

Background

Extracellular vesicles (EVs) are considered as crucial players in a wide variety of biological processes. Although their importance in joint diseases or infections has been shown by numerous studies, much less is known about their function in periprosthetic joint infection (PJI). Our aim was to investigate activated polymorphonuclear (PMN)-derived synovial EVs in patients with PJI.

Questions/Purposes

(1) Is there a difference in the number and size of extracellular vesicles between periprosthetic joint aspirates of patients with PJI and aseptic loosening? (2) Are these vesicles morphologically different in the two groups? (3) Are there activated PMN-derived EVs in septic samples evaluated by flow cytometry after CD177 labelling? (4) Is there a difference in the protein composition carried by septic and aseptic vesicles?

Methods

Thirty-four patients (n = 34) were enrolled into our investigation, 17 with PJI and 17 with aseptic prosthesis loosening. Periprosthetic joint fluid was aspirated and EVs were separated. Samples were analysed by nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM) and flow cytometry (after Annexin V and CD177 labelling). The protein content of the EVs was studied by mass spectrometry (MS).

Results

NTA showed particle size distribution in both groups between 150 nm and 450 nm. The concentration of EVs was significantly higher in the septic samples (p = 0.0105) and showed a different size pattern as compared to the aseptic ones. The vesicular nature of the particles was confirmed by TEM and differential detergent lysis. In the septic group, FC analysis showed a significantly increased event number both after single and double labelling with fluorochrome conjugated Annexin V (p = 0.046) and Annexin V and anti-CD177 (p = 0.0105), respectively. MS detected a significant difference in the abundance of lactotransferrin (p = 0.00646), myeloperoxidase (p = 0.01061), lysozyme C (p = 0.04687), annexin A6 (p = 0.03921) and alpha-2-HS-glycoprotein (p = 0.03146) between the studied groups.

Conclusions

An increased number of activated PMN derived EVs were detected in the synovial fluid of PJI patients with a characteristic size distribution and a specific protein composition. The activated PMNs-derived extracellular vesicles can be potential biomarkers of PJI.

Distinguishing Periprosthetic Crystalline Arthropathy from Infection in Total Knee Arthroplasty: A Systematic Review

Distinguishing periprosthetic crystalline arthropathy from periprosthetic joint infection (PJI) remains a diagnostic challenge as both symptom presentation and diagnostic tests overlap. Accurate differentiation is important as treatment plans vary significantly. We sought to systematically review all cases of total knee arthroplasty (TKA) periprosthetic crystalline arthropathy reported in the literature and summarize clinical, diagnostic, and operative findings in the context of guidelines for diagnosing PJI. The goal of this systematic review is to determine the amount of diagnostic overlap and to identify best practices for differentiating between these two diagnoses. MEDLINE and Google Scholar were searched to identify cases of crystalline arthropathy following TKA. Case reports were reviewed for patient characteristics, clinical symptoms, physical exam, laboratory results, and treatment outcomes. These findings were summarized across patients and dichotomized based on current thresholds for diagnosing PJI according to Musculoskeletal Infection Society criteria. Twenty-six articles were identified which included 42 cases of periprosthetic crystalline arthropathy (17 gout, 16 pseudogout, one both, and eight not specified). Of these cases, 25 presented over 1 year after their index arthroplasty and 15 had no prior history of crystalline arthropathy. Only six cases had a superimposed infection based on aspiration or intraoperative cultures. For cases without a culture-positive infection, several diagnostic tests overlap with PJI thresholds: 95% of patients had C-reactive protein greater than 1 mg/dL, 76% had an erythrocyte sedimentation rate greater than 30 mm/hour, 91% had a synovial white blood cell greater than 3,000 cells, and 76% had a synovial polymorphonuclear cells percent greater than 80%. Patients without co-infection were managed with non-steroidal anti-inflammatory drugs, colchicine, allopurinol, steroids, or a combination of these treatments and most had complete resolution of symptoms within 1 week. Commonly used markers of PJI fail to reliably distinguish periprosthetic crystalline arthropathy from infection. Though clinical judgement and consideration of the implications of delayed treatment for acute PJI remain paramount, in the setting of synovial crystals, surgeons may wish to consider this alternate etiology as the source of the patient's clinical symptoms.

Identification of key biomarkers in steroid-induced osteonecrosis of the femoral head and their correlation with immune infiltration by bioinformatics analysis

Objective

This study aimed to identify key diagnostic markers and immune infiltration of (SONFH) by bioinformatics analysis.

Methods

Related SONFH datasets were downloaded from the Gene Expression Omnibus (GEO) database. First, we identified the differentially expressed genes (DEGs) and performed the functional enrichment analysis. Then weighted correlation network analysis (WGCNA) and the MCODE plug-in in Cytoscape were used to identify the diagnostic markers of SONFH. Finally, CIBERSORT was used to analyze the immune infiltration between SONFH and healthy controls, and the correlation between infiltrating immune cells and diagnostic markers was analyzed.

Results

TYROBP, TLR2, P2RY13, TLR8, HCK, MNDA, and NCF2 may be key diagnostic markers of SONFH. Immune cell infiltration analysis revealed that Memory B cells and activated dendritic cells may be related to the SONFH process. Moreover, HCK was negatively correlated with CD8 T cells, and neutrophils were positively correlated with those key diagnostic markers.

Conclusions

TYROBP, TLR2, P2RY13, TLR8, HCK, MNDA, and NCF2 may be used as diagnostic markers of SONFH, and immune-related mechanism of SONFH and the potential immunotherapy are worthy of further study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-04994-7.

Detecting Periprosthetic Joint Infection by Using Mass Spectrometry

BACKGROUND

Novel methods for diagnosing periprosthetic joint infection (PJI) are currently being explored. Mass spectrometry (MS) is an approach that can detect whole-protein changes in synovial fluid and may represent a promising method.

METHODS

Between March 2017 and July 2018, we successively collected synovial fluid samples from patients who were undergoing diagnostic hip or knee aspiration because PJI was suspected. A PJI diagnosis was based on the modified Musculoskeletal Infection Society (MSIS) criteria. Cluster analysis and receiver operating characteristic (ROC) curves were used to evaluate the results, which were quantitatively confirmed with parallel reaction monitoring in another patient group who underwent aspiration between August 2018 and January 2019.

RESULTS

A total of 117 synovial samples, including 51 PJI and 66 non-PJI samples, were analyzed with liquid chromatography-tandem MS (LC-MS/MS). The cluster analysis sensitivity and specificity based on differentially expressed proteins were 0.961 (95% confidence interval [CI], 0.854 to 0.993) and 0.924 (95% CI, 0.825 to 0.972), respectively. Myeloid nuclear differentiation antigen (MNDA) and polymorphonuclear leukocyte serine protease 3 (PRTN3) were the 2 most important markers for detecting PJI. The areas under the curves (AUCs) of MNDA and PRTN3 were 0.969 (95% CI, 0.936 to 1.000) and 0.900 (95% CI, 0.844 to 0.956), respectively. When MNDA and PRTN3 were combined as variables of a predictive model to diagnose PJI, the AUC reached 0.975 (95% CI, 0.943 to 1.000). Our parallel reaction monitoring-based quantitative analysis of another 40 synovial samples confirmed this result.

CONCLUSIONS

MS could be a powerful tool for diagnosing PJI using proteome information or 2 specific markers, MNDA and PRTN3. The parallel reaction monitoring strategy simplified the PJI detection process and provided quantitative results with similar conclusions.

CLINICAL RELEVANCE

The clinical application of MS adds a new powerful tool for the diagnosis of PJI, and the parallel reaction monitoring strategy lays a foundation for the clinical application of MS.

LEVEL OF EVIDENCE

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

Globulin, the albumin-to-globulin ratio, and fibrinogen perform well in the diagnosis of Periprosthetic joint infection

Background

Although periprosthetic joint infection (PJI) is a severe complication of total joint arthroplasty (TJA), the diagnosis of PJI remains challenging. Albumin (ALB), globulin (GLB), the albumin-to-globulin ratio (AGR), and fibrinogen could be indicators of the body’s inflammatory state. This study aimed to compare the diagnostic accuracy of these biomarkers with that of other inflammatory biomarkers in PJI patients.

Methods

We conducted a retrospective cohort study that included a consecutive series of patients undergoing debridement antibiotic irrigation and implant retention (DAIR), one-stage or the first stage of a two-stage revision total knee arthroplasty (TKA) or total hip arthroplasty (THA) for acute (n = 31) or chronic (n = 51) PJI, or revision TKA or THA for aseptic failures (n = 139) between January 2017 and December 2019 in our hospital. The 2013 criteria of the Musculoskeletal Infection Society (2013 MSIS) were used as the reference standard for the diagnosis of PJI. The preoperative ALB, GLB, AGR, fibrinogen, D-dimer, platelet count, fibrin degradation product (FDP), platelet-to-lymphocyte (PLR), platelet count to mean platelet volume ratio (PVR), neutrophil-to-lymphocyte ratio (NLR), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels were assessed. The receiver operating characteristic curve (ROC), sensitivity, and specificity were utilized to compare different biomarkers.

Results

Compared with the aseptic patients, the GLB, D-dimer, fibrinogen, FDP, platelet count, PVR, PLR, NLR, ESR, and CRP levels of PJI patients were significantly higher (P < 0.01); however, the ALB and AGR levels were significantly lower (P < 0.01). The area under the curve (AUC), sensitivity and specificity were 0.774, 67.50, 77.54% for ALB; 0.820, 57.50, 89.86% for GLB; 0.845, 66.25, 93.48% for AGR; 0.832, 78.48, 78.95% for fibrinogen; 0.877, 81.48, 85.07% for ESR; 0.909, 83.95, 88.89% for CRP; 0.683, 55.22, 75.83% for D-dimer; 0.664, 38.81, 88.33% for FDP; 0.678, 52.44, 79.86% for platelet count; 0.707, 48.78, 86.33% for PVR; 0.700, 51.22, 80.58% for PLR; and 0.678, 52.44, 81.30% for NLR, respectively. In the clinic, GLB, AGR and fibrinogen could be used for diagnosis of patients suspected of having PJI.

Conclusion

Our study demonstrated that GLB, AGR, and fibrinogen were promising biomarkers in the diagnosis of PJI.

Management of Periprosthetic Hip and Knee Joint Infections With a Known Sinus Tract-A Single-Center Experience

Background

Prosthetic joint infection (PJI) is a serious complication after total joint arthroplasty (TJA). A sinus tract communicating with a prosthetic joint is a major criterion defining PJI. Despite this fact, many patients presenting with a draining sinus tract undergo invasive procedures before initiation of two-stage revision arthroplasty. We hypothesized that many patients undergo nondefinitive procedures to treat the sinus tract, rather than undergoing definitive treatment of infection with two-stage revision.

Methods

A retrospective review of all cases of two-stage revision arthroplasty at Loyola University Medical Center between January 2004 and May 2018 was performed. Patients with infected TJA and periprosthetic sinus tract were included. Records were queried for laboratory values and prior procedures.

Results

We identified 160 patients who underwent two-stage revision for infection over the 14-year period. Of the 160 patients, 25 had a documented periprosthetic sinus tract before initiation of definitive revision arthroplasty and were included. Eleven (44.0%) had one or more procedures including interventional radiology drain placement, local wound care, or formal irrigation and debridement before definitive treatment. Forty-five percent of patients that underwent nondefinitive procedures before definitive surgery had either an erythrocyte sedimentation rate or C-reactive protein at normal or near-normal levels.

Conclusion

Many arthroplasty patients presenting with periprosthetic sinus tracts undergo nondefinitive procedures before definitive treatment. Inherent surgical risks of these procedures can increase the overall morbidity and mortality of these patients. Further effort is needed to educate surgeons regarding management of sinus tracts after TJA.

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.

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.

Synovial bone sialoprotein indicates aseptic failure in total joint arthroplasty

Background

Until today, a reliable diagnostic discrimination between periprosthetic joint infections (PJI) and aseptic failure (AF) after total joint arthroplasty (TJA) remains challenging. Nearly all recent research focused on synovial markers to be elevated in PJI rather than in AF patients. In this study, synovial bone sialoprotein (sBSP) was investigated in PJI and AF arthroplasty patients before revision surgery.

Methods

sBSP and C-reactive protein (CRP) were determined in synovial fluid samples of PJI (n = 13) patients fulfilling the MSIS criteria and AF (n = 25) patients. Beside descriptive analysis and comparison, computed statistics determined the area under the receiver operating characteristics curve (AUC) to evaluate the discrimination ability of the tested synovial markers.

Results

In patients with PJI according to the MSIS criteria, mean sBSP was significantly lower: 14.8 ng/ml (95% CI 5.5-24.1) vs. 38.2 ng/ml in the AF group (95% CI 31.1-45.3), p ≤ 0.001. Conversely, mean sCRP was significantly higher in PJI patients: 8.4 μg/ml (95% CI 0-17.2) vs. 1.8 μg/ml in the AF group (95% CI 0.9-2.8), p = 0.032. The AUC of sCRP in PJI patients was 0.71. The AUC of sBSP in AF revision arthroplasty patients was 0.83. The detection of osteolyses was not associated with higher sBSP concentrations.

Conclusions

Considering the MSIS criteria, significantly higher sBSP concentrations were found in synovial fluid samples of AF compared to PJI patients. sCRP showed only fair, sBSP good discrimination potential. If it is not clear whether PJI is present or not, sBSP may be considered as an add-on synovial marker.