The Alpha-Defensin Immunoassay and Leukocyte Esterase Colorimetric Strip Test for the Diagnosis of Periprosthetic Infection: A Systematic Review and Meta-Analysis

Evolution of temporomandibular joint reconstruction: from autologous tissue transplantation to alloplastic joint replacement

The reconstruction of the temporomandibular joint presents a multifaceted clinical challenge in the realm of head and neck surgery, underscored by its relatively infrequent occurrence and the lack of comprehensive clinical guidelines. This review aims to elucidate the available approaches for TMJ reconstruction, with a particular emphasis on recent groundbreaking advancements. The current spectrum of TMJ reconstruction integrates diverse surgical techniques, such as costochondral grafting, coronoid process grafting, revascularized fibula transfer, transport distraction osteogenesis, and alloplastic TMJ replacement. Despite the available options, a singular, universally accepted 'gold standard' for reconstructive techniques or materials remains elusive in this field. Our review comprehensively summarizes the current available methods of TMJ reconstruction, focusing on both autologous and alloplastic prostheses. It delves into the differences of each surgical technique and outlines the implications of recent technological advances, such as 3D printing, which hold the promise of enhancing surgical precision and patient outcomes. This evolutionary progress aims not only to improve the immediate results of reconstruction but also to ensure the long-term health and functionality of the TMJ, thereby improving the quality of life for patients with end-stage TMJ disorders.

What Are the Research Highlights of Periprosthetic Joint Infections From the 100 Most Cited Studies?

Background

Periprosthetic joint infections (PJIs) are a serious complication after total joint arthroplasty. Our study aimed to analyze the characteristics and research highlights of the top 100 most cited studies on PJI from an orthopaedic standpoint. Moreover, we sought to assess whether there has been a change in the level of evidence (LOE) throughout time.

Methods

We conducted a search of the PubMed, Embase, and Web of Science databases to identify the top 100 studies primarily focusing on PJI. Study characteristics assessed included publication year, LOE, journal of publication, and type of study. Research highlights of the included studies were classified into 6 sections. Linear regression was employed to assess correlation between LOE and publication year.

Results

The aggregated citation count of all studies was 19,558 and the median citation number was 129.5. While cohort studies were the most prevalent, articles focusing on analysis of costs associated with PJI care or PJI definition garnered the highest yearly citation counts. The bulk of included studies were concentrated in 3 orthopaedic journals and published in the 2010s. The majority of studies had a LOE II (30%) or III (34%). On regression analysis, LOE was not correlated with publication year (Pearson's r = 0.013, P = .61).

Conclusions

The most cited PJI articles assessed the definition of PJI and PJI cost. Despite growing interest in PJI, the majority of studies had LOE II or III, highlighting the difficulty of conducting prospective randomized controlled trials in PJI patients.

Level of evidence

IV.

What is the diagnostic accuracy of neutrophil to lymphocyte ratio and monocyte to lymphocyte ratio in detecting acute periprosthetic joint infections? A gender-specific analysis

PURPOSE

The accurate and timely diagnosis of periprosthetic joint infection (PJI) is critical for guiding optimal treatment management and success, highlighting the requirement of readily available inexpensive serum biomarkers to increase the diagnostic accuracy for PJI. Many studies have investigated the diagnostic accuracy of neutrophil to lymphocyte ratio (NLR) and monocyte to lymphocyte ratio (MLR). However, there is a lack of existing literature regarding optimal thresholds for acute PJI. The purpose of this study was to reveal the most appropriate cut-off values for MLR and NLR in detecting acute PJI with a gender specific analysis.

METHODS

Patients were classified as having an acute PJI if they met the International Consensus Meeting (ICM) 2018 modified criteria. Patients who had a negative clinical and diagnostic workup for a PJI and the presence of erythema on the index surgical area were included in the erysipelas group (control group). Data obtained from all patients included age, sex, body mass index (BMI), Charlson Comorbidity Index (CCI), procedure type (THA or TKA), serum C-reactive protein (CRP), and blood studies at the admission and culture results were retrieved from the electronic medical record.

RESULTS

ROC curve analysis was used to determine the gender-specific optimal threshold values for CRP, NLR, and MLR. Comparing the sensitivities and specificities of NLR and MLR at the identified best thresholds in males and females, the study found similar sensitivities of NLR in males and females with 0.84 and 0.84, respectively. On the other hand, an MLR of 0.67 or more reported a notably higher specificity in male patients [0.90 (95% CI 0.75-0.96) versus 0.70 (95% CI 0.56-0.80)].

CONCLUSION

NLR and MLR represent commonly ordered, low-cost, simple, and readily available complete cell count laboratory values and should be used as adjunct tests with reasonable diagnostic accuracy in detecting acute PJIs. Moreover, with its excellent specificity and PPV, MLR could provide valuable insight in diagnosing acute PJI, particularly in male patients.

LEVEL OF EVIDENCE

Level III Retrospective Cohort analysis.

Comparative performance analysis of Synovasure™ and Leukocyte Esterase assays for the diagnosis of periprosthetic infections in complex microbiological situations

INTRODUCTION

Osteoarticular infections (OAI) after prosthetic surgery have serious functional and economic consequences. Rapid tests for alpha-defensin (TAD) and leukocyte esterase (TLE) are two intra-articular markers involved in the diagnosis of OAIs. TLE cannot be applied in the presence of blood unless centrifugation is used, but the rate of "non-application" of the test for this reason is unknown in complex microbiological situations (discordant or negative puncture, ongoing antibiotic treatment). We therefore conducted a prospective study to determine: 1) the performance of the TAD and TLE rapid tests in diagnosing complex OAI, 2) the rate of non-application of the TLE due to hemarthrosis, and 3) the concordance between the two tests.

ASSUMPTION

These two diagnostic tests had a negative predictive value (NPV) ≥ 90% for the diagnosis of complex OAI.

MATERIALS AND METHODS

A total of 79 suspected OAI patients with complex microbiological diagnoses were included between 2018 and 2023. They were 52 men (66%) for 27 women (34%), with a mean age of 66 ± 13.5 years. The hip (n = 41, 52%) and knee (n = 36, 46%) were the most represented, followed by the elbow (n = 1, 1%) and shoulder (n = 1, 1%). These patients were suspected of having an OAI that required joint puncture, but with a complex microbiological diagnosis due to discordant punctures (n = 21, 27%) or sterile punctures despite strong suspicion of infection (n = 50, 63%), or in case of ongoing antibiotic treatment (n = 8, 10%). All patients underwent joint fluid puncture followed by TAD (Synovasure™, Zimmer, Warsaw, IN, USA) and, when the macroscopic appearance of the sample allowed (clear fluid group), TLE (Multistix 8SG, Siemens Healthcare GmbH, Erlangen, Germany). The results of both tests were compared with Musculoskeletal Infection Society (MSIS) criteria.

RESULTS

Of the 79 patients included, 27 (34%) were considered infected according to the MSIS. In 30% of cases (n = 24), TLE was not feasible due to the presence of blood in the joint fluid. In the "clear fluid" group, the NPV was equal to 90% for both TAD (sensitivity 87%, specificity 88%) and TLE (sensitivity 87%, specificity 81%). The two parameters showed almost perfect agreement (κ = 0.927).

CONCLUSION

TAD and TLE are two rapid, reliable tests with near-perfect concordance and high NPV, even in situations of complex microbiological diagnosis. They are particularly useful for deciding on a therapeutic strategy for patients with complex OAI. The TLE cannot be used in 30% of cases due to hemarthrosis, but centrifugation can correct this defect.

LEVEL OF EVIDENCE

III; Prospective comparative diagnostic accuracy study.

Relationship between the clinical outcomes and the systemic inflammatory response index and systemic immune inflammation index after total knee arthroplasty

BACKGROUND

Periprosthetic joint infection (PJI) is an extremely damaging complication that can occur after total knee arthroplasty (TKA). There is no study in the literature investigating the relationship between systemic inflammatory response index (SIRI) and systemic inflammation immune index (SII) values and prognosis and infection in patients who have undergone TKA. The aim of the study was to determine the relationship between the inflammatory index values and the rate of PJI in patients who had previously had TKA.

METHODS

A total of 187 patients who underwent TKA between 2015 and 2023 years were retrospectively analyzed.

RESULTS

The median value of the postoperative SII index was 1862.3 (1146.6-2630.4) in the infected group, while it was 1058.2 (605.0-1762.8) in the non-infected group (p < 0.001). In the infected group, the median value of preoperative SIRI was observed as 2.3 (1.7-3.5), while in the non-infected group it was 0.9 (0.7-1.5) (p < 0.001). The cutoff value for postoperative SIRI was observed to be 2.19, with a sensitivity value of 95%, a specificity value of 46%, the AUC value observed was 65%. The cutoff value for the postoperative SII index was observed to be 1058.96, with a sensitivity value of 100%, a specificity value of 50%.

CONCLUSIONS

Our study has associated the inflammatory markers SIRI, SII, neutrophil lymphocyte ratio, and platelet lymphocyte ratio with PJI, which are easy and inexpensive to obtain. There is no widely recognized serum biomarker that can be used alone with good sensitivity and specificity. This study contributes to finding the gold standard inflammatory marker for diagnosing 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.

Diagnostic Test Performances for Identifying Periprosthetic Joint Infection in Hip Hemiarthroplasty

INTRODUCTION

Periprosthetic joint infection (PJI) is a devastating complication of hip hemiarthroplasty (HHA) that is not well-represented in the literature. Therefore, this study aimed to evaluate diagnostic markers for identifying PJI in patients after HHA and compare them with the most recent 2018 International Consensus Meeting on Musculoskeletal Infection criteria.

METHODS

A total of 98 patients (64 PJIs, 65.3%) were analyzed. Patients were identified by relevant Current Procedural Terminology and International Classification of Diseases-9/10 codes from 2000 to 2021 across a single healthcare system. Preoperative or intraoperative synovial fluid nucleated cell (NC) count, synovial polymorphonuclear (PMN) percentage, serum erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), and serum white blood cell count were compared with Student t -test between aseptic and septic cohorts. Diagnostic utility and laboratory cutoff values were determined using receiver-operating characteristic curves and Youden index, respectively.

RESULTS

Mean values were significantly higher in the septic cohort for synovial NC count (120,992.2 versus 1,498.0 cells/μL, P < 0.001), synovial PMN percentage (91.3% versus 56.2%, P < 0.001), serum ESR (75.6 versus 36.3 mm/hr, P < 0.001), serum CRP (20.2 versus 125.8 mg/L, P < 0.001), and serum white blood cell count (8.5 versus 11.5 cells/μL, P < 0.001). Synovial NC count, synovial PMN percentage, and serum CRP had excellent PJI discriminatory ability with an area under the curve of 0.99, 0.90, and 0.93, respectively. Optimal cutoffs were 2,700 cells/μL for synovial NC count (100% sensitivity and 94% specificity), 81.0% for synovial PMN percentage (96% sensitivity and 89% specificity), 52.0 mm/hr for serum ESR (75% sensitivity and 80% specificity), and 40.0 mg/L for serum CRP (85% sensitivity and 92% specificity).

CONCLUSION

Our findings support the continued use of routine serum and synovial fluid tests for diagnosing PJI in HHA patients. Optimal cutoff values for both synovial fluid biomarkers were very close in alignment with the 2018 International Consensus Meeting criteria.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Different biomarker ratios in peripheral blood have limited value in diagnosing periprosthetic joint infection after total joint arthroplasty: a single-center, retrospective study

BACKGROUND

Periprosthetic joint infection (PJI) is a severe complication that can occur after total joint arthroplasty (TJA). The timely and accurate diagnosis of PJI is the key to treatment. This study investigated the diagnostic value of platelet to lymphocyte ratio (PLR), platelet count to mean platelet volume ratio (PVR), neutrophil to lymphocyte ratio (NLR) and monocyte to lymphocyte ratio (MLR) in PJI after total knee arthroplasty (TKA) and total hip arthroplasty (THA).

METHODS

We performed a retrospective analysis of the patients who underwent revision hip or knee arthroplasty at our Institute between June 2015 and June 2020. Of the 187 patients reviewed, 168 were included in the study. According to the diagnostic criteria of the Musculoskeletal Infection Society (MSIS), 58 patients were in the PJI group, and 110 patients were in the aseptic loosening (AL) group. We recorded and compared the preoperative peripheral blood white blood cell (WBC) count, platelet count (PLT), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), PLR, PVR, NLR, and MLR in both groups. The diagnostic performance of the WBC, PLT, PLR, PVR, NLR, and MLR individually and in combination with the ESR and CRP for PJI diagnosis was evaluated by receiver operating characteristic (ROC) curves, and the sensitivity, specificity, positive predictive value, and negative predictive value were calculated.

RESULTS

Compared to those in the AL group, the mean WBC, PLT, ESR, CRP, PLR, PVR, NLR, and MLR in the peripheral blood of the PJI group were significantly greater (P < 0.05). The analysis of the ROC curve revealed that the ESR, CRP, PLR, PVR, NLR, and MLR in peripheral blood had moderate effectiveness in diagnosing PJI, with area under the curve (AUC) values of 0.760 (95% CI: 0.688-0.823), 0.758 (95% CI: 0.687-0.821), 0.714 (95% CI: 0.639-0.781), 0.709 (95% CI: 0.634-0.777), 0.723 (95% CI: 0.649-0.789), and 0.728 (95% CI: 0.654-0.793), respectively. Conversely, the WBC and PLT counts demonstrated poor diagnostic value for PJI, with AUC values of 0.578 (95% CI: 0.499-0.653) and 0.694 (95% CI: 0.619-0.763), respectively. The results of the prediction model calculations revealed that the combined AUC of the WBC, PLT, ESR, CRP, PLR, PVR, NLR, and MLR was the highest at 0.853 (95% CI, 0.790-0.909), indicating good value in the diagnosis of PJI, with a sensitivity of 82.8% and a specificity of 72.7%. Moreover, the novel composite of parameters improved the accuracy and reliability in diagnosing PJI compared to the traditional biomarkers ESR and CRP (P = 0.015).

CONCLUSION

Our study suggested that the diagnostic value of the peripheral blood biomarkers PLR, PVR, NLR, and MLR for diagnosing PJI is limited and not superior to that of the ESR or CRP. However, when the WBC, PLT, ESR, CRP, PLR, PVR, NLR, and MLR are combined, the diagnostic performance of PJI in TJA patients can be improved.

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.

Diagnosis and Management of Infected Total Ankle Replacements

As the number of primary total ankle replacements increases for treatment of end-stage ankle arthritis, failures are also expected to rise. Periprosthetic joint infection is among the causes of failures and has been reported to be as high as 5%. Diagnosis is usually made by a combination of clinical examination findings, imaging, laboratory, and microbiological workup. Management is generally separated into limb salvage or amputation. Limb salvage can be challenging and may involve a single versus staged approach. Options include revision arthroplasty or arthrodesis procedures (ankle versus tibiotalocalcaneal), and a multidisciplinary approach is sought to eradicate infection before definitive management.

Periprosthetic joint infection and immunity: Current understanding of host-microbe interplay

Periprosthetic joint infection (PJI) is a major complication of total joint arthroplasty. Even with current treatments, failure rates are unacceptably high with a 5-year mortality rate of 26%. Majority of the literature in the field has focused on development of better biomarkers for diagnostics and treatment strategies including innovate antibiotic delivery systems, antibiofilm agents, and bacteriophages. Nevertheless, the role of the immune system, our first line of defense during PJI, is not well understood. Evidence of infection in PJI patients is found within circulation, synovial fluid, and tissue and include numerous cytokines, metabolites, antimicrobial peptides, and soluble receptors that are part of the PJI diagnosis workup. Macrophages, neutrophils, and myeloid-derived suppressor cells (MDSCs) are initially recruited into the joint by chemokines and cytokines produced by immune cells and bacteria and are activated by pathogen-associated molecular patterns. While these cells are efficient killers of planktonic bacteria by phagocytosis, opsonization, degranulation, and recruitment of adaptive immune cells, biofilm-associated bacteria are troublesome. Biofilm is not only a physical barrier for the immune system but also elicits effector functions. Additionally, bacteria have developed mechanisms to evade the immune system by inactivating effector molecules, promoting killing or anti-inflammatory effector cell phenotypes, and intracellular persistence and dissemination. Understanding these shortcomings and the mechanisms by which bacteria can subvert the immune system may open new approaches to better prepare our own immune system to combat PJI. Furthermore, preoperative immune system assessment and screening for dysregulation may aid in developing preventative interventions to decrease PJI incidence.

Development of Diagnostic Quality Metrics for Prosthetic Joint Infection

ABSTRACT

Although well-accepted clinical practice guidelines exist for the diagnosis of prosthetic joint infection (PJI), little is known about the quality of diagnosis for PJI. The identification of quality gaps in the diagnosis of PJI would facilitate the development of care structures and processes to shorten time to diagnosis and reduce the significant morbidity, mortality, and economic burden associated with this condition. Hence, we sought to develop valid clinical quality measures to improve the timeliness and accuracy of PJI diagnosis. We convened a nine-member multidisciplinary national panel of PJI experts including orthopedic surgeons, infectious disease specialists, an emergency medicine physician, and a patient previously treated for PJI to review, discuss, and rate the validity of proposed measures using a modification of the RAND-UCLA appropriateness method. In total, 57 permutations of six proposed measures were rated. Populations considered to be at high enough risk for PJI that certain care processes should always be performed were identified by the panel. Among the proposed quality measures, the panel rated five as valid. These novel clinical quality measures could provide insight into care gaps in the diagnosis of PJI.

The Diagnostic Utility of Fast Tests for Detecting C-Reactive Protein in Synovial Fluid in Periprosthetic Joint Infections

BACKGROUND

Despite the fact that many synovial fluid biomarkers have found application in the routine diagnosis of periprosthetic joint infection (PJI), this process still remains a challenge for orthopaedic surgeons. To simplify this process, fast point-of-care (POC) tests can be used during ambulatory visits and in operating room conditions. However, before such tests can be routinely used in clinical practice, they require validation. The purpose of the present study was to evaluate the diagnostic accuracy of different fast POC tests for detecting C-reactive protein (CRP) in synovial fluid for the diagnosis of PJI.

METHODS

Synovial fluid samples were collected from 120 consecutive patients who underwent revision total joint arthroplasty (TJA). The patients were divided into 2 groups. The first group included 76 patients who underwent revision for reasons other than infection (the aseptic revision TJA [arTJA] group), and the second group included 44 patients who underwent revision because of periprosthetic joint infection (PJI). The diagnosis of infection was made according to the International Consensus Meeting (ICM) 2018 criteria. All patients were operatively treated at a single orthopaedic center from January 2022 to February 2023. Four fast CRP tests with different cutoff values (1 and 3 mg/L, ≥8 mg/L, ≥10 mg/L [cassette], ≥10 mg/L [strip]) were used off-label for synovial fluid testing. Tests were performed on the same synovial fluid samples, and the results of these tests were compared with those obtained with the laboratory method.

RESULTS

The cassette test with a minimum cutoff value of ≥8 mg/L demonstrated the best accuracy for the diagnosis of chronic PJI, with a sensitivity and specificity of 90.9% and 90.8%, respectively. For the cassette test with a cutoff value of >3 mg/L, the sensitivity and specificity were 68.2% and 77.6%, respectively. For the tests with a minimum cutoff value of ≥10 mg/L, the sensitivity and specificity were 77.3% and 94.7%, respectively, for the cassette test and 77.3% and 96.1%, respectively, for the strip test. The laboratory method with the statistically calculated threshold (2.7 mg/L) revealed the highest AUC (area under the receiver operating characteristic curve) value (0.95), with 90.9% sensitivity and 94.7% specificity.

CONCLUSIONS

The cassette POC test with the minimum cutoff value of ≥8 mg/L had very good accuracy for the diagnosis of chronic PJI. This test had comparable sensitivity and slightly lower specificity in comparison with the laboratory method with the calculated threshold of 2.7 mg/L.

LEVEL OF EVIDENCE

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

Utility of Blood Cell Ratio Combinations for Diagnosis of Periprosthetic Joint Infection

Background

Periprosthetic joint infection (PJI) is a serious complication following joint replacement surgery, and its diagnosis can be challenging due to the similarity of symptoms to other conditions and the lack of confirmatory imaging tests. Platelet/mean platelet volume ratio (PVR), platelet/lymphocyte ratio, monocyte/lymphocyte ratio, and neutrophil/lymphocyte ratio have been proposed as potential markers to aid in the diagnosis of PJI. This study aimed to further assess the utility of these blood cell ratio combinations for the diagnosis of PJI.

Methods

A retrospective chart review was conducted on patients who presented to a university hospital for evaluation for PJI or underwent aseptic revision surgery. All patients were reviewed for inclusion in the study. Data were collected on several markers, including complete blood counts, synovial fluid white blood cell count, and polymorphonuclear percentage. Receiver operator characteristic curve analysis was used to evaluate the diagnostic capabilities of the markers and marker combinations.

Results

The combination of erythrocyte sedimentation rate, C-reactive protein, synovial white blood cell count, and synovial polymorphonuclear percentage, with PVR, had the highest area under the curve of 0.97, with a sensitivity of 94.3% and a specificity of 88.9%, and a positive predictive value of 97.1% and a negative predictive value of 80.0%.

Conclusions

This study further supports the use of PVR calculated from complete blood count commonly ordered laboratory values obtained during routine complete blood counts when combined with established serum and synovial markers to increase the diagnostic accuracy for diagnosing PJI.

Role of α-Defensin and the Microbiome in Prosthetic Joint Infection: A Prospective Cohort Study in Korea

The utility of α-defensin (AD), leukocyte esterase (LE) levels, and metagenomics sequencing as diagnostic tools for prosthetic joint infection (PJI) has been suggested, but there are few studies among the Asian population. This study aimed to evaluate the diagnostic performance of various biomarkers for PJI and the role of the microbiome in the synovial fluid of patients with prostheses. Patients with suspected knee PJI were enrolled, and their blood and synovial fluid were collected. The cases were classified into the PJI and non-PJI groups. Significant differences between the two groups were observed in the levels of AD (4698 µg/L vs. 296 µg/L, p < 0.001) and positivity for LE (62.5% vs. 21.1%, p = 0.01). AD had 94.4% sensitivity and 89.5% specificity for diagnosing PJI, whereas LE had 37.5% sensitivity and 100% specificity. Microbiome taxonomic profiling showed high sensitivity. The number of operational taxonomic units and the richness of the microbiome in the synovial fluid were higher in the non-PJI than in the PJI group. AD has shown encouraging results in the Asian population as a diagnostic biomarker for PJI, and LE can be used as a diagnostic adjunct. The bacterial richness of the synovial fluid is likely associated with infections.

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.

Utility of Diagnostic Markers in Late Periprosthetic Joint Infection Workup for Total Knee Arthroplasty Patients Who Received Antibiotics 48 Hours Before Aspiration

BACKGROUND

Diagnosing periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) remains challenging despite recent advancements in testing and evolving criteria over the last decade. Moreover, the effects of antibiotic use on diagnostic markers are not fully understood. Thus, this study sought to determine the influence of antibiotic use within 48 hours before knee aspiration on synovial and serum laboratory values for suspected late PJI.

METHODS

Patients who underwent a TKA and subsequent knee arthrocentesis for PJI workup at least 6 weeks after their index arthroplasty were reviewed across a single healthcare system from 2013 to 2020. Median synovial white blood cell (WBC) count, synovial polymorphonuclear (PMN) percentage, serum erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), and serum WBC count were compared between immediate antibiotic and nonantibiotic PJI groups. Receiver operating characteristic (ROC) curves and Youden's index were used to determine test performance and diagnostic cutoffs for the immediate antibiotics group.

RESULTS

The immediate antibiotics group had significantly more culture-negative PJIs than the no antibiotics group (38.1 versus 16.2%, P = .0124). Synovial WBC count demonstrated excellent discriminatory ability for late PJI in the immediate antibiotics group (area under curve, AUC = 0.97), followed by synovial PMN percentage (AUC = 0.88), serum CRP (AUC = 0.86), and serum ESR (AUC = 0.82).

CONCLUSION

Antibiotic use immediately preceding knee aspiration should not preclude the utility of synovial and serum lab values for the diagnosis of late PJI. Instead, these markers should be considered thoroughly during infection workup considering the high rate of culture-negative PJI in these patients.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Current relevance of biomarkers in diagnosis of periprosthetic joint infection: an update

With a significant rise in the number of arthroplasty procedures performed worldwide, the increasing revision burden posed by periprosthetic joint infection (PJI) is a matter of growing concern. In spite of various attempts to diagnose PJI, there are no defined tests that can be called a gold standard. Given the importance of early diagnosis in PJI, newer tests and biomarkers have been introduced to improve cumulative diagnostic accuracy. Novel biomarkers like calprotectin, lipocalcin, monocyte-to-lymphocyte ratio, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio and platelet-to-mean platelet volume ratio have demonstrated a potential as diagnostic biomarkers for PJI. This article discusses the relevance of available and newly described diagnostic biomarkers to provide a perspective on the practical applicability in current medical practice, as well as highlights some recent advances in biomarkers for the diagnosis of PJI.

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.

Serum CD64 as a Marker for Chronic Periprosthetic Joint Infection

Background

Serum cluster of differentiation 64 (CD64) has emerged as a diagnostic test for musculoskeletal infections. The purpose of this study was to evaluate the utility of serum CD64 in diagnosing periprosthetic joint infections (PJIs) compared to conventional markers like white blood count (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and interleukin-6 (IL-6).

Methods

A prospective case-control study on patients undergoing revision hip or knee arthroplasty surgery >6 weeks after their index surgery was performed at a single institution. Whole blood samples were drawn within 24 hours prior to revision surgery for white blood count, ESR, CRP, IL-6, and CD64. Intraoperative cultures were obtained during the revision, and PJI was defined using the major criteria from the 2018 Musculoskeletal Infection Society criteria. Two-sample Wilcoxon rank-sum test and Fisher's exact test were used to determine if there were significant differences in serum laboratory values between patients with and without infection. The sensitivity, specificity, positive predictive value (PPV), negative predictive value, and accuracy of each test were calculated.

Results

With an average age of 67 years, 39 patients with 15 revision THAs and 24 TKAs, were included. 19 patients (48.7%) were determined to have PJI. Patients with PJI had significantly higher CD64 (P = .036), CRP (P = .016), and ESR (P = .045). CD64 had the highest specificity (100%) and PPV (100%), moderate accuracy (69.2%), but low sensitivity (37.0%) and negative predictive value (62.5%).

Conclusions

Given the high specificity, PPV, and accuracy, CD64 may be an excellent confirmatory test to help diagnose PJI.

Emerging Technologies in Diagnosing Periprosthetic Joint Infections

Periprosthetic joint infection (PJI) is a well-known serious complication following joint replacement surgeries and is responsible for high failure rates of implanted devices. Any delay in the diagnosis can compromise treatment success, putting a huge burden on the patients' wellness and healthcare systems. Diagnosing PJIs is quite complex as there is still no gold standard test to reach the definitive diagnosis in a timely manner. A number of laboratory tests and radiological imaging inventions have evolved in the past few years, requiring consistent updates of the available guidelines to keep up with the latest advances in the field. This article highlights the recent advances in diagnosing PJIs and discusses their validity for use in clinical practice.

Two-stage revision in periprosthetic knee joint infections

Periprosthetic joint infection (PJI) following total knee arthroplasty is one of the most catastrophic and costly complications that carries significant patient wellness as well as economic burdens. The road to efficiently diagnosing and treating PJI is challenging, as there is still no gold standard method to reach the diagnosis as early as desired. There are also international controversies with respect to the best approach to manage PJI cases. In this review, we highlight recent advances in managing PJI following knee arthroplasty surgery and discuss in depth the two-stage revision method.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

III, case-control retrospective analysis.

Evaluation of Synovial Calprotectin by Using a Lateral Flow Test for the Diagnosis of Prosthetic Joint Infections

The analysis of synovial fluid is a crucial step in the diagnosis of prosthetic joint infections (PJIs). Recently several studies illustrated the efficacy of synovial calprotectin in supporting the diagnosis of PJI. In this study, synovial calprotectin was analyzed by a commercial stool test to explore whether it might accurately predict PJIs. The synovial fluids of 55 patients were analyzed and calprotectin levels were compared to other synovial biomarkers of PJI. Of the 55 synovial flu-ids, 12 patients were diagnosed with PJI and 43 with an aseptic failure of the implant. Specificity, sensitivity, and AUC of calprotectin resulted in 0.944, 0.80, and 0.852 (95%CI: 0.971-1.00), respectively, with a set threshold of 529.5 µg/g. Calprotectin had a statistically relevant correlation with the synovial leucocyte counts (rs = 0.69, p < 0.001) and the percentage of synovial neutrophils (rs = 0.61, p < 0.001). From this analysis, it can be concluded that synovial calprotectin is a valuable biomarker that correlates with other established indicators of local infection, and the use of a commercial lateral flow stool test could be a cost-effective strategy delivering rapid and reliable results and supporting the diagnostic process of PJI.

Application of Nucleic Acid-Based Strategies to Detect Infectious Pathogens in Orthopaedic Implant-Related Infection

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Implant-associated infection in orthopaedic surgery remains an enormous and largely unsolved clinical problem with a high rate of persistent or recurrent infection. This may be due, at least in part, to the potential for underdiagnosis by traditional microbial culture or the potential for culture to incompletely identify the microbial species present.

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Nucleic acid-based diagnostic techniques, focused on using the diagnostic information contained in DNA or RNA to identify microbial species, have been developing rapidly and have garnered escalating interest for both clinical and research applications.

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Commonly applied techniques include end-point polymerase chain reaction (PCR), quantitative PCR, Sanger sequencing, and next-generation sequencing. Understanding the specific strengths and weaknesses of each technique is critical to understanding their utility, applying the correct assessment strategy, and critically understanding and interpreting research.

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The best practices for interpreting nucleic acid-based diagnostic techniques include considering positive and negative controls, reads per sample, detection thresholds (for differentiating contaminants from positive results), and the primer set or targeted regions.

Wound alpha defensin levels are significantly higher in patients with fracture related infection: A pilot, prospective cohort study

BACKGROUND

In absence of frank purulence, wound cultures represent 'gold-standard' for diagnosis of fracture related infection (FRI). However, these are time-intensive, and may be falsely negative, necessitating the need for accurate and rapid biomarker-based diagnosis. We conducted this study to determine the accuracy of 3 wound-based biomarkers for the diagnosis of FRI.

METHODS

This was a prospective cohort study on adult patients who underwent an operative procedure for an upper or lower limb fracture. Wound fluid levels of alpha-defensin (AD), neutrophil elastase (NE) and IL-6 were evaluated on post-operative day 2, and patients were followed up for one month. Patients were categorized as cases (FRI) or controls (no FRI), on the basis of the consensus definition of FRI. Univariate analysis, along with receiver operating characteristic (ROC) analysis was performed.

RESULTS

48 patients were included. AD levels showed a 2.6-fold elevation in cases (n = 26, Median = 23.74 µg/ml) as compared to controls (n = 22, Median = 8.78 µg/ml). The area under the curve for this variable was 0.71 (95% Confidence Intervals = 0.56 - 0.86). The levels of NE and IL-6 were not significantly different between cases and controls.

CONCLUSION

Wound AD levels are significantly elevated in patients with FRI. However, these results need to be validated in a larger cohort of patients before it can be used as a biomarker of FRI.

Long Pentraxin 3 as a New Biomarker for Diagnosis of Hip and Knee Periprosthetic Joint Infections

BACKGROUND

Preoperative diagnosis of periprosthetic joint infections (PJIs) poses an unmet clinical challenge. The long pentraxin PTX3 is a component of the innate immune system involved in infection immunity. This study evaluated the potential of synovial and plasmatic PTX3 in the diagnosis of hip and knee PJIs.

METHODS

Consecutive total hip and knee arthroplasty (THA/TKA) revisions were prospectively included and classified as septic or aseptic according to the European Bone and Joint Infection Society (EBJIS) and Musculoskeletal Infection Society (MSIS) criteria. The concentration of PTX3 in plasma and synovial fluid samples was measured with ELISA. The AUC, threshold value, sensitivity, specificity, and positive and negative likelihood ratios were calculated using the ROC (receiver operating characteristic) curve method.

RESULTS

The study population included 128 patients (94 THAs; 34 TKAs). The AUC of the synovial PTX3 based on EBJIS criteria was 0.85 (p < 0.0001), with a sensitivity of 81.13% and a specificity of 93.33%. The AUC based on MSIS criteria was 0.95 (p < 0.001), with a sensitivity of 91.43% and a specificity of 89.25%. Plasmatic PTX3 failed to discriminate infected from non-infected patients.

CONCLUSIONS

Synovial PTX3 demonstrated an excellent diagnostic potential in hip and knee PJIs, with a very high specificity irrespective of the diagnostic criteria for PJI.

Synovial Fluid Absolute Neutrophil Count and Neutrophil-To-Lymphocyte Ratio are not Superior to Polymorphonuclear Percentage in Detecting Periprosthetic Joint Infection

BACKGROUND

Serum and synovial biomarkers are currently used to diagnose periprosthetic joint infection (PJI). Serum neutrophil-to-lymphocyte ratio (NLR) has shown promise as an inexpensive test in diagnosing infection, but there are no reports of synovial NLR or absolute neutrophil count (ANC) for diagnosing chronic PJI. The purpose of this study was to investigate the diagnostic potential of both markers.

METHODS

A retrospective review of 730 patients who underwent total joint arthroplasty and subsequent aspiration was conducted. Synovial white blood cell (WBC) count, synovial polymorphonuclear percentage (PMN%), synovial NLR, synovial ANC, serum erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), serum WBC, serum PMN%, serum NLR, and serum ANC had their utility in diagnosing PJI examined by area-under-the-curve analyses (AUC). Pairwise comparisons of AUCs were performed.

RESULTS

The AUCs for synovial WBC, PMN%, NLR, and ANC were 0.84, 0.84, 0.83, and 0.85, respectively. Synovial fluid ANC was a superior marker to synovial NLR (P = .027) and synovial WBC (P = .003) but not PMN% (P = .365). Synovial NLR was inferior to PMN% (P = .006) but not different from synovial WBC (P > .05). The AUCs for serum ESR, CRP, WBC, PMN%, NLR, and ANC were 0.70, 0.79, 0.63, 0.72, 0.74, and 0.67, respectively. Serum CRP outperformed all other serum markers (P < .05) except for PMN% and NLR (P > .05). Serum PMN% and NLR were similar to serum ESR (P > .05).

CONCLUSION

Synovial ANC had similar performance to PMN% in diagnosing chronic PJI, whereas synovial NLR was a worse diagnostic marker. The lack of superiority to synovial PMN% limits the utility of these tests compared to established criteria.

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.

Alpha-Defensin Offers Limited Utility in Work-Up Prior to Reimplantation in Chronic Periprosthetic Joint Infection in Total Joint Arthroplasty Patients

BACKGROUND

Alpha-defensin (AD) is a synovial biomarker included in the 2018 consensus criteria for diagnosing periprosthetic joint infection (PJI). Its value in assessing eradication of infection prior to second stage reimplantation is unclear. The purpose of this study was to evaluate the impact of AD on eligibility for reimplantation following resection for chronic PJI.

METHODS

This study included patients who previously underwent resection arthroplasty for PJI. Synovial fluid aspirated from 87 patients was retrospectively reviewed. All patients completed a 6-week course of intravenous antibiotics and an appropriate drug holiday. Synovial white blood cell count, percentage neutrophils, and culture from the AD immunoassay laboratory were reviewed with serum erythrocyte sedimentation rate and C-reactive protein values from our institution. A modified version of the 2018 consensus criteria was used, including white blood cell count, percentage neutrophils, erythrocyte sedimentation rate, and C-reactive protein. AD was then added to determine if it changed diagnosis or clinical management.

RESULTS

Four patients were categorized as "infected" (score >6), none exhibited a positive AD or positive culture. Sixty eight patients were diagnosed as "possibly infected" (score 2 to 5), none had a positive AD, and one had a positive culture (Cutibacterium acnes). AD did not change the diagnosis from "possibly infected" to "infected" in any case or alter treatment plans. Fifteen patients had a score of <2 (not infected) and none had a positive AD.

CONCLUSION

The routine use of AD in the work-up prior to a second-stage arthroplasty procedure for PJI may not be warranted.

Use of α-Defensins to Help Diagnose Nosocomial Ventriculitis

Ventriculitis is a severe complication of indwelling neurosurgical devices that is associated with significant morbidity and mortality. The incidence rate of ventriculitis is approximately 10% with external ventricular drains. Obstinately, patients with these indwelling neurosurgical devices are prone to have traditional cerebral spinal fluid parameters that lack sensitivity and specificity in diagnosing nosocomial ventriculitis. In addition, diagnosis can be arduous given that indolent pathogens are commonly implicated. Therefore, diagnosis is difficult but paramount to thwart the morbidity and mortality associated with this infectious condition as well as to reduce the prolonged use of broad-spectrum antibiotics. As we extrapolate from prosthetic joint infections, for which diagnosis can also be challenging, we learn that the use of α-defensins as a diagnostic biomarker for nosocomial ventriculitis may hold promise. Herein, the viewpoint of using α-defensins as a diagnostic biomarker for nosocomial ventriculitis is discussed.

Management of periprosthetic knee joint infections: focus on the role of Nuclear Medicine (v2)

BACKGROUND

When faced with a painful knee replacement, ruling out infection is mandatory to set the correct therapeutic approach. However, it is not always easy, especially in subclinical/chronic infections. A multidisciplinary approach is necessary to assess in the most correct way each case of suspected periprosthetic knee joint infection. This review explores the role of nuclear medicine investigations in the management of periprosthetic knee infections and their proper use within a multidisciplinary pathway.

METHODS

A PubMed search was conducted selecting studies from the past 10 years.

RESULTS

Triphasic bone scintigraphy has high sensitivity (93%) but poor specificity (56%) for periprosthetic joint infections of the knee, with a high negative predictive value (NPV), ranging from 96% to 100%. Consequently, a negative bone scan is useful in ruling out infection. In contrast, radiolabeled leukocyte scintigraphy is characterized by a sensitivity of 85.7-93%, specificity of 93.6-100%, diagnostic accuracy of 92.6-98%, NPV of 93-97.8%, and positive predictive value (PPV) of 66.7-100%. By adding a tomographic acquisition with hybrid single-photon emission computed tomography combined with computed tomography technique (SPECT/CT), the diagnostic accuracy increases. Because 18F-fluorodeoxyglucose (FDG) accumulates at both sites of inflammation and infection, FDG positron emission tomography (PET/CT) shows low specificity.

CONCLUSIONS

A common decision-making process in the diagnosis of periprosthetic joint infection is not yet validated and multidisciplinary integration is mandatory. In this context, nuclear medicine can contribute decisively.

Infection after total joint replacement of the hip and knee: research programme including the INFORM RCT

Background

People with severe osteoarthritis, other joint conditions or injury may have joint replacement to reduce pain and disability. In the UK in 2019, over 200,000 hip and knee replacements were performed. About 1 in 100 replacements becomes infected, and most people with infected replacements require further surgery.

Objectives

To investigate why some patients are predisposed to joint infections and how this affects patients and the NHS, and to evaluate treatments.

Design

Systematic reviews, joint registry analyses, qualitative interviews, a randomised controlled trial, health economic analyses and a discrete choice questionnaire.

Setting

Our studies are relevant to the NHS, to the Swedish health system and internationally.

Participants

People with prosthetic joint infection after hip or knee replacement and surgeons.

Interventions

Revision of hip prosthetic joint infection with a single- or two-stage procedure.

Main outcome measures

Long-term patient-reported outcomes and reinfection. Cost-effectiveness of revision strategies over 18 months from two perspectives: health-care provider and Personal Social Services, and societal.

Data sources

National Joint Registry; literature databases; published cohort studies; interviews with 67 patients and 35 surgeons; a patient discrete choice questionnaire; and the INFORM (INFection ORthopaedic Management) randomised trial.

Review methods

Systematic reviews of studies reporting risk factors, diagnosis, treatment outcomes and cost comparisons. Individual patient data meta-analysis.

Results

In registry analyses, about 0.62% and 0.75% of patients with hip and knee replacement, respectively, had joint infection requiring surgery. Rates were four times greater after aseptic revision. The costs of inpatient and day-case admissions in people with hip prosthetic joint infection were about five times higher than those in people with no infection, an additional cost of > £30,000. People described devastating effects of hip and knee prosthetic joint infection and treatment. In the treatment of hip prosthetic joint infection, a two-stage procedure with or without a cement spacer had a greater negative impact on patient well-being than a single- or two-stage procedure with a custom-made articulating spacer. Surgeons described the significant emotional impact of hip and knee prosthetic joint infection and the importance of a supportive multidisciplinary team. In systematic reviews and registry analyses, the risk factors for hip and knee prosthetic joint infection included male sex, diagnoses other than osteoarthritis, high body mass index, poor physical status, diabetes, dementia and liver disease. Evidence linking health-care setting and surgeon experience with prosthetic joint infection was inconsistent. Uncemented fixation, posterior approach and ceramic bearings were associated with lower infection risk after hip replacement. In our systematic review, synovial fluid alpha-defensin and leucocyte esterase showed high diagnostic accuracy for prosthetic joint infection. Systematic reviews and individual patient data meta-analysis showed similar reinfection outcomes in patients with hip or knee prosthetic joint infection treated with single- and two-stage revision. In registry analysis, there was a higher rate of early rerevision after single-stage revision for hip prosthetic joint infection, but, overall, 40% fewer operations are required as part of a single-stage procedure than as part of a two-stage procedure. The treatment of hip or knee prosthetic joint infection with early debridement and implant retention may be effective in > 60% of cases. In the INFORM randomised controlled trial, 140 patients with hip prosthetic joint infection were randomised to single- or two-stage revision. Eighteen months after randomisation, pain, function and stiffness were similar between the randomised groups (p = 0.98), and there were no differences in reinfection rates. Patient outcomes improved earlier in the single-stage than in the two-stage group. Participants randomised to a single-stage procedure had lower costs (mean difference –£10,055, 95% confidence interval –£19,568 to –£542) and higher quality-adjusted life-years (mean difference 0.06, 95% confidence interval –0.07 to 0.18) than those randomised to a two-stage procedure. Single-stage was the more cost-effective option, with an incremental net monetary benefit at a threshold of £20,000 per quality-adjusted life-year of £11,167 (95% confidence interval £638 to £21,696). In a discrete choice questionnaire completed by 57 patients 18 months after surgery to treat hip prosthetic joint infection, the most valued characteristics in decisions about revision were the ability to engage in valued activities and a quick return to normal activity.

Limitations

Some research was specific to people with hip prosthetic joint infection. Study populations in meta-analyses and registry analyses may have been selected for joint replacement and specific treatments. The INFORM trial was not powered to study reinfection and was limited to 18 months’ follow-up. The qualitative study subgroups were small.

Conclusions

We identified risk factors, diagnostic biomarkers, effective treatments and patient preferences for the treatment of hip and knee prosthetic joint infection. The risk factors include male sex, diagnoses other than osteoarthritis, specific comorbidities and surgical factors. Synovial fluid alpha-defensin and leucocyte esterase showed high diagnostic accuracy. Infection is devastating for patients and surgeons, both of whom describe the need for support during treatment. Debridement and implant retention is effective, particularly if performed early. For infected hip replacements, single- and two-stage revision appear equally efficacious, but single-stage has better early results, is cost-effective at 18-month follow-up and is increasingly used. Patients prefer treatments that allow full functional return within 3–9 months.

Future work

For people with infection, develop information, counselling, peer support and care pathways. Develop supportive care and information for patients and health-care professionals to enable the early recognition of infections. Compare alternative and new treatment strategies in hip and knee prosthetic joint infection. Assess diagnostic methods and establish NHS diagnostic criteria.

Study registration

The INFORM randomised controlled trial is registered as ISRCTN10956306. All systematic reviews were registered in PROSPERO (as CRD42017069526, CRD42015023485, CRD42018106503, CRD42018114592, CRD42015023704, CRD42017057513, CRD42015016559, CRD42015017327 and CRD42015016664).

Funding

This project was funded by the National Institute for Health and Care Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 10, No. 10. See the NIHR Journals Library website for further project information.

Which Minor Criteria is the Most Accurate Predictor for the Diagnosis of Hip and Knee Periprosthetic Joint Infection in the Asian Population?

BACKGROUND

The aim of this study was to evaluate the diagnostic performance of minor criteria from the 2018 International Consensus Meeting (ICM) for the diagnosis of chronic periprosthetic joint infection (PJI) in an Asian population.

METHODS

We retrospectively reviewed 76 patients who underwent a revision knee or hip arthroplasty at an academic institution between September 2018 and December 2019. All major and minor 2018 ICM criteria were available for all patients included. Cases with at least 1 major criterion or score ≥6 in minor criteria were considered as infected. The diagnostic performance was evaluated by a receiver operative characteristic curve analysis and area under the curve (AUC) for each minor criterion. An AUC value of more than 0.9 was considered outstanding and 0.8-0.9 as excellent.

RESULTS

When using 2018 ICM threshold, the diagnostic performance ranked based on AUC was the following: alpha defensin (0.92), positive histology (0.83), leukocyte esterase (0.82), synovial white blood cell (0.81), serum erythrocyte sedimentation rate (0.78), synovial polymorphonuclear neutrophils (0.77), serum C-reactive protein (0.74), D-dimer (0.59), single positive culture (0.53), and positive intraoperative purulence (0.51). Alpha defensin was considered as an outstanding test among the 2018 ICM minor criteria. Positive histology, leukocyte esterase, and synovial white blood cell were considered as excellent tests.

CONCLUSION

Based on our findings, alpha-defensin has the best diagnostic performance in Asian population among the minor criteria of 2018 ICM.

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.

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.

Synovial fluid calprotectin in diagnosing periprosthetic joint infection: A meta-analysis

Purpose

Periprosthetic joint infection (PJI) is one of the most debilitating complications following joint replacement surgery. Synovial biomarkers, such as Calprotectin, have become valuable in the diagnosis of PJI. This meta-analysis aimed to investigate the role of synovial Calprotectin as a diagnostic test in PJI.

Methods

This meta-analysis was conducted with adherence to PRISMA guidelines. PubMed, Cochrane, Web of Science, and Google Scholar were searched until February 2022. Inclusion criteria were as follows: all studies in which the patients with joint replacements were evaluated for PJI; synovial Calprotectin was the biomarker of choice to diagnose PJI; standardized guidelines were used as the gold standard for the diagnosis; and a comparison between the guidelines and Calprotectin results was made. Diagnostic parameters such as sensitivity, specificity, diagnostic odds ratio (DOR), positive predictive value, negative predictive value, and area under the curve (AUC) were calculated for the included studies to evaluate synovial Calprotectin for PJI diagnosis.

Results

The total number of the included patients was 618 from eight studies. The pooled sensitivity, specificity, and diagnostic odds ratio of Calprotectin test were 92% (95%CI: 84%-98%), 93% (95%CI: 84%-99%), and 187.61 (95%CI: 20.21–1741.18), respectively. The results showed that the negative and positive likelihood ratios of the Calprotectin test were 0.07 (95%CI: 0.02–0.22) and 9.91 (95%CI: 4.11–23.93), respectively. The SROC showed that the area under the curve for Calprotectin test was 0.935.

Conclusion

Synovial Calprotectin is a valuable biomarker as it provides a reliable and rapid diagnosis of PJI. It has the potential to be used in clinical practice due to its high sensitivity and specificity that are comparable to the other utilized biomarkers. Another advantage is its low cost relative to other biomarkers.

Bacterial Identification and Visualization of Bacterial Biofilms Adjacent to Fracture Sites After Internal Fixation

Objectives: The primary aims of this study were to determine if any correlation exists in cases of fracture fixation among: (1) bacterial profiles recovered from the instrumentation and adjacent tissues; (2) the type of orthopedic injury; and (3) the clinical outcome-union versus nonunion. A secondary goal was to compare culture and molecular diagnostics for identifying the bacterial species present following fracture fixation. Design: Single-institution, prospective case-control cohort study. Setting: Single level 1 trauma center. Patients: Forty-nine bony nonunion cases undergoing revision internal fixation and 45 healed fracture controls undergoing removal of hardware. Intervention: Bacterial infection was detected by standard microbial culture methods and by a pan-eubacterial domain, molecular diagnostic (MDx) assay. Confirmation of culture and MDx results was achieved with bacterial ribosomal 16S rRNA fluorescence in situ hybridization (FISH) to visualize bacterial biofilms. Main Outcome Measurements: MDx and microbial culture methods results were the primary study outcomes. Results: Ninety-four percent of the nonunion cohort and 93% of the union cohort had bacteria detected by the MDx. Seventy-eight percent of the nonunion cases and 69% of the controls were culture negative, but MDx positive. Although no significant differences in bacterial composition were observed between the cases and controls, differences were observed when cases were divided by comorbidities. Conclusion: The MDx is more sensitive than microbial culture in detecting bacterial presence. The lack of significantly different findings with regard to bacterial profile identified between the cases and controls suggests that host factors and environmental conditions are largely responsible for determining if bony union will occur. Level of Evidence: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The Potential Value of Monocyte to Lymphocyte Ratio, Platelet to Mean Platelet Volume Ratio in the Diagnosis of Periprosthetic Joint Infections

OBJECTIVE

To explore the possibility of obtaining more accurate information from routine blood tests for the diagnosis of periprosthetic joint infection (PJI).

METHODS

This is a retrospective study. Between 2017 and 2018, a total of 246 patients who underwent total hip or knee revision surgery were included in this study. There were 146 females and 100 males, and the mean age of the patients was 62.1 ± 12.75 years. Laboratory parameters erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), D-dimer, plasma fibrinogen, serum white blood cell (WBC), and calculable ratio markers were collected. Based on leukocytes (monocyte count, neutrophil count, lymphocyte count), platelet count, and mean platelet volume Inflammation-related ratio markers were calculated, which including monocyte to lymphocyte ratio (MLR), neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and platelet to mean platelet volume ratio (PMR). Follow-up of all studied cases for at least 1 year. The diagnostic value of the markers based on the receiver operating characteristic (ROC) analysis. The most optimal combinations of blood markers were selected by the prediction models. Statistical analyses and prediction models were performed using R software.

RESULTS

Of the 246 patients, 125 were diagnosed with PJI and 121 with aseptic loosening. A higher rate of patients underwent revision surgery due to hip prosthesis loosening in the aseptic loosening group (74.4%) compared to the PJI group (45.6%, P < 0.001). ROC curves showed that the area under the curve (AUC) for classical markers, fibrinogen was 0.853 (95% confidence interval [CI], 0.805-0.901), ESR was 0.836 (95% CI, 0.785-0.887) and CRP was 0.825 (95% CI, 0.773-0.878). Followed by the PMR, PLR, NLR and MLR, which showed promising diagnostic performance with AUCs of 0.791, 0.785, 0.736, and 0.733. The AUCs of the ratio markers were higher than those of D-dimer (0.691;95% CI, 0.6243-0.7584) and serum WBC (0.622; 95% CI, 0.552-0.691). After the predictive model calculation, AUC was up to 0.923 (95% CI, 0.891-0.951) when plasma fibrinogen combined with MLR and PMR and interpreted excellent discriminatory capacity with a sensitivity of 86.40% and a specificity of 84.17%. The new combination significantly increases the accuracy and reliability of the diagnosis of PJI (P < 0.001). The AUC increased to 0.899 (95% CI, 0.861-0.931; P = 0.007) and 0.916 (95% CI, 0.880-0.946; P < 0.001), followed by CRP and ESR, respectively. All plasma fibrinogen, ESR, and CRP combined with both PMR and MLR achieved the highest specificity (89.17%) and PPV (85.34%).

CONCLUSION

The diagnostic performance greatly improved when plasma fibrinogen, ESR, and CRP combined with ratio markers.

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.

Application of ica D, eno, sar A and agr gene testing in early diagnosis of periprosthetic joint infection

Objective This study intends to explore the diagnostic efficiency and value of PCR in the early diagnosis of periprosthetic joint infection (PJI) based on the testing of the four staphylococcal specific genes ica D, eno, sar A and agr. Methods 41 samples of ultrasonic cleavage RNA eluate were extracted from the human joint model of PJI caused by the five most common PJI pathogens to detect the PCR of ica D, eno, sar A and agr genes. Based on the detection results, the sensitivity, specificity, positive and negative predictive value and accuracy of the four genes were analyzed and compared. Results eno test had a high sensitivity (83.33%). However, more false positive results affected the test specificity (47.06%); sar A test did not show false positive results, but the specificity was high (100%), but the sensitivity was low (41.67%); the sensitivity of ica D and agr test was 4.17% and 0%, respectively, and the clinical value was limited. Conclusion eno and sar A gene detection is of high value in early diagnosis of PJI. Reasonable design and sequential application of eno sensitivity preliminary diagnosis and sar A specific screening of false positive results are more beneficial to the early diagnosis of staphylococcal pathogenic PJI.

Diagnosis and management of infected arthroplasty

Periprosthetic joint infection (PJI) is one of the most dreadful complications after THA and TKA. Though prevention is of utmost importance in PJI management, the last decade has seen many remarkable developments in PJI diagnosis, including the introduction of several standardized PJI diagnostic definitions and biomarkers. Depending on the specific clinical situation, a myriad of treatment options for PJI are offered. Our review aims to summarize the pertinent information on PJI diagnosis and synthesize literature on the different treatment methods currently used in clinical practice. One of the most accepted PJI diagnostic definitions was developed by the Musculoskeletal Infection Society (MSIS) in 2011, later modified in the 2013 International Consensus Meeting (ICM). After promising results from studies, alpha-defensins and D-dimer were recently incorporated into the 2018 ICM PJI definition. The management choices for PJI include irrigation and debridement (DAIR), one-stage exchange arthroplasty, or two-stage exchange arthroplasty, to name a few. While two-stage revision has traditionally been the treatment of choice in the United States, there has been a growing body of evidence framing one-stage revision as a comparable choice. One-stage revision should be offered in patients meeting strict selection criteria: no sinus tract, proper soft tissue available for wound closure, appropriate bone stock, a favorable identifiable organism with encouraging antibiotic sensitivities (for cement and oral suppression later), and robust immunological status. DAIR can be considered in case of early infections with sensitive infecting organisms. Patients with multiple unsuccessful revisions or those who refuse further surgical intervention for PJI can be offered antibiotic suppression. If nothing seems to work, salvage procedures (resection arthroplasty and arthrodesis) are available as a last resort. Further research is encouraged to improve on diagnostic capabilities and develop evidence on the best treatment of choice for PJI.

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.

Diagnostic value of routine pre-operative investigations used in combination in the diagnosis of periprosthetic joint infection

The primary aim of this study was to assess the diagnostic accuracy of joint aspiration culture, serum C-reactive protein (CRP) and serum erythrocyte sedimentation rate (ESR), individually, and in combination for the diagnosis of periprosthetic joint infection (PJI). A consecutive patient series with pre-operative inflammatory marker levels, an aspiration culture of either hip or knee arthroplasty and intra-operative culture samples from subsequent revision surgery was compiled. This retrospective patient cohort analysis included 128 aspiration. The data were analysed to compare pre-operative aspiration cultures, serum ESR and CRP levels to the chosen gold standard for PJI diagnosis of intra-operative culture samples. A diagnostic algorithm was created using the above tests combined with clinical suspicion index. The values that had the highest sensitivity and specificity of predicting PJI were >5 for CRP and >16 for ESR. CRP used individually had the highest sensitivity and negative predictive value (NPV) of any test (75.0% and 75.9%, respectively). ESR + aspirate had the highest specificity and positive predictive value (PPV), of 100% for both. Using all three tests together the specificity and PPV were higher than the test individual values (95.3% and 85.0% respectively). Based on subgroup analyses the combination of ESR or CRP plus joint aspiration has superior PPV compared to individual tests. ESR and CRP had the highest NPV when used in isolation. An algorithm has been developed to guide clinical diagnosis.

The Alpha-Defensin Prosthetic Joint Infection Test Has Poor Validity for Native Knee Joint Infection

BACKGROUND

The alpha-defensin test known as Synovaure has been very effective in diagnosis of prosthetic joint infections (PJIs). Being able to easily and accurately differentiate septic and inflammatory arthropathies in native joints would improve diagnostic workup and management. We tested the ability of an alpha-defensin test to distinguish septic from inflammatory or crystalline arthropathy in the native knee.

METHODS

40 native knee joint fluid specimens were tested with cell count, fluid analysis, and culture and alpha-defensin testing. We determined the sensitivity and specificity of the alpha-defensin test using culture-positive fluid as the gold standard for septic arthropathy and positive crystals as the gold standard for crystalline arthropathy.

RESULTS

The Synovasure PJI test had 100% specificity for septic arthritis coupled with a 28% false-positive rate when applied to native knee aspirations. False-positive rate was 5.3 times higher in patients with crystals found in the joint fluid.

CONCLUSION

Alpha-defensin testing, in the form of the Synovasure PJI test, has a high-false-positive rate when used to distinguish septic and inflammatory arthritis in the native knee joint. Future work will need to determine the sensitivity and specificity of the newer native joint panel. Clinicians should be cognizant of the specific alpha-defensin test used when sampling native knee synovial fluid.

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.].

Leukocyte Esterase and Glucose Reagent Test Can Rule in and Rule out Septic Arthritis

BACKGROUND/AIM

Septic arthritis (SA) requires rapid diagnosis and therapy to avoid joint damage. This study evaluated the diagnostic accuracy of leukocyte esterase (LE) and glucose (GLC) strip tests for diagnosing SA.

PATIENTS AND METHODS

Synovial fluids from 455 patients with atraumatic joint effusions were assessed prospectively over a 5-year period with LE and glucose strip tests. Results were compared to modified Newman criteria for diagnosing joint infections. Synovial fluid cultures, crystal, blood and synovial cell analyses were also performed.

RESULTS

Forty-one patients had SA and 252 non-SA. A positive LE reading combined with negative glucose reading could detect SA with 100% specificity, 85% sensitivity, 100% positive predictive value (PPV) and 98% negative predictive value (NPV). Positive synovial LE reading alone detected SA with 82% specificity, 95% sensitivity, 47% PPV, and 99% NPV.

CONCLUSION

Combined LE and glucose strip tests represent a low-cost tool for rapidly diagnosing or ruling out SA.

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.