Novel diagnostic markers for periprosthetic joint infection: a systematic review

Clinical Benefit of Using Differential Cutoff Values of Synovial C-Reactive Protein in Acute and Chronic Infected as Well as Aseptic Hip and Knee Revision Arthroplasties

BACKGROUND

It is unclear whether cutoff values for synovial C-reactive protein (syCRP) differ between acute and chronic infected as well as aseptic revision total hip arthroplasty (rTHA) and revision total knee arthroplasty (rTKA). We aimed to evaluate this and to compare the diagnostic accuracy of syCRP with serum C-reactive protein (seCRP), synovial white blood cell count, and polymorphonuclear leukocyte percentage (syPMN%).

METHODS

A total of 387 revision arthroplasties (83 rTHA, 304 rTKA) were analyzed for seCRP, syCRP, synovial white blood cell, syPMN%, and culture results. Using the International Consensus Meeting 2018 periprosthetic joint infection (PJI) criteria, 189 (42 rTHA, 147 rTKA) were classified as infected, and 198 (41 rTHA, 157 rTKA) were aseptic revisions. Diagnostic accuracy was assessed using receiver operating characteristic curves and area under the curve (AUC).

RESULTS

The optimal syCRP cutoff for PJI diagnosis among rTHA and rTKA < 90 days was 9.05 mg/L (AUC: 0.85) and 4.95 mg/L (AUC: 0.92), respectively. For > 90 days, the optimal syCRP cutoff was 3.00 mg/L (AUC: 0.90) for THA and 1.65 mg/L (AUC: 0.88) for TKA. In early and late acute PJI (n = 48), syCRP (45 of 48 = 94%) showed a higher positivity rate than seCRP (43 of 48 = 90%), WBC (38 of 48 = 79%), and PMN% (42 of 48 = 88%). A similar trend was observed in chronic PJI (n = 141): syCRP (110 of 141 = 78%), seCRP (104 of 141 = 74%), WBC (105 of 141 = 74%), and PMN% (101 of 141 = 72%). Among 189 confirmed PJIs, both WBC and PMN% were negative in 34 of 189 (18%), of which syCRP and seCRP were positive in 13 of 34 (38%) and 10 of 34 (29%), respectively.

CONCLUSIONS

The syCRP may be useful as a supplementary biomarker in cases with suspected PJI, but normal synovial cell count. Our data suggest that different cutoff values based on the type of joint and the chronicity of rTHA and rTKA are clinically useful.

The Predictive Value of Heparin-Binding Protein in Total Joint Arthroplasty Prosthesis Infections

Objective: This study aims to explore the predictive value of heparin-binding protein (HBP) in diagnosing prosthesis infections after total joint arthroplasty (TJA), in order to provide a new biomarker for early identification and management of prosthetic joint infections (PJI) post-TJA. Methods: A retrospective analysis of data from 168 patients who underwent TJA revision at Lianyungang First People's Hospital from October 2020 to March 2024 was conducted. The participants were divided into an infection group (38 cases) and a non-infection group (94 cases). Inclusion criteria included all patients undergoing joint prosthesis revision who had preoperative HBP levels measured. Primary assessment parameters included HBP, C-reactive protein (CRP), white blood cell (WBC) count, and erythrocyte sedimentation rate (ESR). Univariate analysis and multivariate regression analysis were used to evaluate the correlation of these factors with PJI, and the performance of HBP in predicting PJI was analyzed using the receiver operating characteristic (ROC) curve. Results: There were significant statistical differences in HBP, CRP, WBC, and ESR between the infection and non-infection groups (p < 0.05). Multivariate regression analysis showed that HBP is an independent predictive factor for the risk of PJI. The area under the ROC curve was 0.856, indicating that HBP has good predictive performance. The optimal cutoff value for HBP was 51.3, with a sensitivity of 69.2% and a specificity of 89.5%. Conclusion: The study found that HBP levels are significantly associated with the occurrence of PJI following TJA, serving as an effective independent predictive factor for PJI risk. HBP has high predictive value and can be considered an important biomarker for predicting PJI post-TJA in clinical settings, aiding in the early identification and management of PJI, thereby improving patient treatment outcomes and quality of life.

The Application of artificial intelligence in periprosthetic joint infection

Periprosthetic joint infection (PJI) represents one of the most devastating complications following total joint arthroplasty, often necessitating additional surgeries and antimicrobial therapy, and potentially leading to disability. This significantly increases the burden on both patients and the healthcare system. Given the considerable suffering caused by PJI, its prevention and treatment have long been focal points of concern. However, challenges remain in accurately assessing individual risk, preventing the infection, improving diagnostic methods, and enhancing treatment outcomes. The development and application of artificial intelligence (AI) technologies have introduced new, more efficient possibilities for the management of many diseases. In this article, we review the applications of AI in the prevention, diagnosis, and treatment of PJI, and explore how AI methodologies might achieve individualized risk prediction, improve diagnostic algorithms through biomarkers and pathology, and enhance the efficacy of antimicrobial and surgical treatments. We hope that through multimodal AI applications, intelligent management of PJI can be realized in the future.

The Utility of Synovial Fluid Interleukin-10 in Diagnosing Chronic Periprosthetic Joint Infection: A Prospective Cohort Study

Background

Diagnosing chronic periprosthetic joint infection (PJI) is challenging. Synovial fluid interleukin-10 (SF IL-10), an anti-inflammatory cytokine produced by leukocytes, plays a pivotal role in inflammation and infection regulation. However, limited research has explored the diagnostic potential of SF IL-10 in chronic PJI patients.

Objective

The study aimed to investigate the relationship between SF IL-10 and incidence of chronic PIJ, and to evaluate its diagnostic reliability.

Design and Methods

We analyzed data from 137 patients who underwent revision surgery for aseptic loosening or chronic PJI between 2017 and 2019 in our hospital. PJI diagnoses followed the 2013 International Consensus Meeting criteria. We measured serum ESR, serum CRP, SF PMN%, SF WBC and SF IL-10 levels, using logistic regression and receiver operating characteristic (ROC) curves to evaluate associations and diagnostic accuracy.

Results

Demographic data showed no significant differences. However, SF IL-10 levels differed significantly between groups. Logistic regression indicated a strong association between SF IL-10 and chronic PJI (OR = 1.11, 95% CI 1.05~1.17, p < 0.001). At a cut-off of 10.305 pg/mL, SF IL-10 had an area under the ROC curve (AUC) of 0.891, with 92.16% sensitivity and 77.91% specificity. Adding SF IL-10 to traditional models improved risk prediction for chronic PJI (net reclassification improvement [NRI]: 0.167 [0.023 ~ 0.312]; integrated discrimination improvement [IDI]: 0.160 [0.096 ~ 0.224]).

Conclusion

Higher SF IL-10 levels were significantly associated with chronic PJI in revision surgery patients, and incorporating SF IL-10 into the traditional risk model enhanced its predictive value for chronic PJI in these patients.

A Narrative Review of Fungal Periprosthetic Joint Infections of the Hip and Knee: Risk Factors, Microbiological Profiles, and Treatment Challenges

Fungal periprosthetic joint infections (PJIs) are rare but increasingly recognized complications following total joint arthroplasty (TJA). While Candida albicans remains the most common pathogen, non-albicans Candida species and other fungi, such as Aspergillus, have gained prominence. These infections often present with subtle clinical features and affect patients with significant comorbidities or immunosuppression. Compared to bacterial PJIs, fungal infections pose unique diagnostic and therapeutic challenges, including biofilm formation, limited antifungal susceptibility, and protracted treatment courses. This narrative review synthesizes current evidence from research articles and review/metanalysis papers, focusing on fungal PJIs. The literature search encompassed publications from 2015 to 2024, identifying key insights on epidemiology, risk factors, microbiological profiles, diagnostic methods, therapeutic strategies, and outcomes. Both classical references and recent studies addressing emerging diagnostic biomarkers and biofilm-active therapies were included. It was shown that C. albicans remains the primary fungal pathogen in PJIs but non-albicans Candida species and other fungi are associated with more complex clinical scenarios, higher recurrence rates, and reduced infection-free survival. Patients commonly exhibit multiple comorbidities, compromised immune status, and previous prosthetic revisions. Diagnosis is complicated by slow-growing organisms and nonspecific inflammatory markers, prompting interest in novel diagnostics such as alpha-defensin, calprotectin, and next-generation sequencing. Two-stage revision arthroplasty, supplemented by prolonged targeted antifungal therapy, is considered the gold standard for chronic infections, although outcomes remain inferior to bacterial PJIs. Emerging strategies, including antifungal-impregnated beads and biofilm-disrupting agents, may improve local infection control. In conclusion, fungal PJIs constitute a challenging clinical entity demanding tailored diagnostic and therapeutic approaches. Further research into standardized diagnostic criteria, optimized antifungal regimens, biomarker validation, and refined surgical strategies is essential. Multidisciplinary collaboration, enhanced patient optimization, and innovative biofilm-directed therapies hold promise for improving outcomes and reducing the burden of fungal PJIs.

Results of a monocentric field study: value of histology compared to sonication method and conventional tissue culture in the diagnosis of periprosthetic joint infection (PJI)

BACKGROUND

To confirm the diagnosis of periprosthetic joint infection (PJI), the Infectious Diseases Society of America (IDSA) and the International Consensus Meeting (ICM) have defined criteria that include histology as a minor criterion and the sonication method only as an additional criterion. The aim of this monocentric, retrospective study was to investigate the value of histology and whether sonication leads to a more accurate diagnosis.

MATERIALS AND METHODS

All revision surgeries for knee and hip arthroplasty between 2017 and 2020 were included. With regard to microbiological diagnostic, conventional culture of periprosthetic biopsies and sonication of explant material were performed. In addition, histology and non-specific inflammatory markers (CRP, leukocytes) were recorded.

RESULTS

A total of 78 patients with PJI and 62 aseptic controls were included. From both microbiological methods (conventional culture / sonication), Staphyloccus (S.) epidermidis and S. aureus were detected most frequently. However, compared to the conventional microbiology, a higher sensitivity was calculated for sonication, albeit with a lower specificity in relation to a PJI. In two logistic regression models for the significance of all diagnostic parameters in PJI, the AUC was 0.92 and 0.96 with histology in particular making the decisive contribution in both models (p < 0. 001, both models).

CONCLUSION

Since histology showed the highest accuracy in the current study, its importance in the PJI criteria should be reevaluated. Sonication shows a high sensitivity for germ detection with a lower specificity and should only be used in combination with the conventional culture for microbiolgical diagnostics.

Fracture-related infection blood-based biomarkers: Diagnostic strategies

Fracture-related infections are significant postoperative complications that carry substantial patient burden and additional healthcare costs. Despite their impact on outcome, early diagnosis of these infections remains challenging due to current available tests lacking acceptable diagnostic parameters. This review compiles existing information on blood-based biomarkers that have been evaluated as early diagnostic tools and highlights the challenges in their reliability. To begin to overcome these challenges new avenues of biomarker discovery utilizing "omics" technologies and novel analytical methods are being investigated in recent years. It appears that, despite their complexity, these newer approaches may be the future in biomarker discovery for fracture-related infection diagnosis.

Feasibility of mNGS in joint replacement patients exhibiting elevated ESR and CRP levels without an underlying diagnosis

OBJECTIVE

The aim of this study is to investigate the viability of performing initial artificial joint replacement surgery in patients presenting with unexplained elevations in erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels.

METHODS

A cohort of 22 patients, comprising 11 cases each for knee and hip joint replacements, who underwent initial artificial joint replacement surgery between November 2020 and January 2022, was recruited. All patients exhibited elevated levels of ESR and CRP prior to surgery, the etiology of which remained undetermined. Intraoperatively, joint effusion and periarticular tissues were preserved for subsequent bacterial culture and metagenomic next-generation sequencing (mNGS). Postoperatively, a combination of intravenous and local antibiotics was administered for anti-infective management. In cases where bacterial culture and/or mNGS yielded positive results, patients were diagnosed with periprosthetic joint infections (PJI) and underwent one-stage revision; conversely, negative findings led to the discontinuation of intravenous and local antibiotics therapy.

RESULTS

Among the cohort of 22 patients, bacterial cultures yielded negative results, while mNGS identified bacterial infection in 14 patients (63.63%), viral infection in 1 patient (4.55%), and yielded negative results in 7 patients (31.82%). All surgical incisions achieved per primam. Subsequent follow-up assessments conducted for more than 1 year postoperatively revealed absence of PJI among the patients, all of whom exhibited satisfactory progress in their rehabilitation exercises. Notably, the Knee Society Score (KSS) for knee joint patients significantly improved from a preoperative mean of 48.7 ± 3.3 points to 84.3 ± 2.2 points postoperatively, whereas the Harris Hip Score for hip joint patients increased significantly from preoperative mean of 50.6 ± 3.6 points to 87.1 ± 1.6 points (P < 0.01).

CONCLUSION

In cases where patients present with unexplained elevations in ESR and CRP levels, primary artificial joint replacement can be undertaken following a one-stage revision approach for PJI.

Construction and evaluation of a combined diagnostic model for chronic periprosthetic joint infection based on serological tests

BACKGROUND

Early diagnosis of chronic periprosthetic joint infection (CPJI) is crucial for ensuring effective treatment and improving patient outcomes. However, many auxiliary diagnostic tests are challenging to implement on a large scale due to economic and technical constraints, making CPJI diagnosis difficult. This study aims to design and validate a combined diagnostic model based on commonly used serological tests to evaluate its diagnostic value for CPJI and develop a diagnostic nomogram.

METHODS

A retrospective study from January 2019 to February 2024 involving 170 patients undergoing knee and hip arthroplasty revision for CPJI and aseptic loosening (AL) was conducted across two medical centers. These patients were divided into the training set and validation set. Patients were categorized into CPJI and AL groups based on infection status. Serological tests conducted upon admission were collected, and single-factor and multi-factor logistic regression analyses were used to identify independent diagnostic factors for early infection. These factors were integrated to construct a nomogram model. The model's performance was evaluated using the receiver operating characteristic area under the curve (AUC), Hosmer-Lemeshow test, decision curve analysis (DCA), and calibration curve, with external validation conducted on the validation set.

RESULTS

Multivariate logistic regression analysis showed that C-reactive protein (CRP), procalcitonin (PCT), and Platelet count/mean platelet volume ratio (PVR) were independent diagnostic factors for CPJI (p < 0.05). The AUCs for diagnosing CPJI using these individual factors were 0.806, 0.616, and 0.700 (p < 0.05), respectively, while their combined detection achieved an AUC of 0.861 (p < 0.05). The DCA clinical impact curve shows the combined model has good clinical utility when the threshold probability of infection presence is between 0.16 and 0.95. Similar results were obtained in the external validation cohort, with the combined detection having an AUC of 0.893.

CONCLUSION

The combined diagnostic model of CRP, PCT, and PVR significantly improves the The combined diagnostic model of CRP, PCT, and PVR significantly improves the diagnostic performance for CPJI compared to individual serum biomarkers. It exhibits good sensitivity, specificity, and clinical applicability, providing valuable references for CPJI diagnosis.

Active myeloperoxidase: a promising biomarker to differentiate "acute" and "low-grade" peri-prosthetic joint infections from aseptic failures

Introduction

The accurate distinction between periprosthetic joint infections (PJI) and aseptic failures (AF) is of paramount importance due to differences in treatment. However, this could be challenging by using the current criteria. Various synovial fluid biomarkers are being assessed to improve the diagnostic accuracy. Myeloperoxidase (MPO), an enzyme contained in the granules of neutrophils, may be a promising biomarker for PJI.

Methods

Synovial fluids of 99 patients (n = 65 PJI according to EBJIS criteria; n = 34 AF) were collected in two specialized orthopedic centers. PJI were divided into acute (n = 33) and low-grade (n = 32) according to previously published classification. An activity assay specific for active MPO was performed in each sample. Ability of MPO to correctly discriminate patients with PJI from AF was determined by ROC analysis. The best discriminating cut-off value was determined by calculating the J Youden index. For all analyses, a P value < 0.05 was considered statistically significant.

Results

Active MPO was higher in PJI than AF (P < 0.0001). The ROC analysis revealed a significant area under the curve (AUC: 0.86; 95% CI: 0.78-0.93, P < 0.0001). A cut-off value of 561.9 U/mL, with good sensitivity (0.69) and specificity (0.88), discriminated between AF and PJI (accuracy 75.76%, 95% CI: 66.11-83.81%, positive likelihood ratio 5.88, 95% CI: 2.31-14.98 and negative likelihood ratio 0.35, 95%CI: 0.24-0.51). No difference in MPO levels was found between acute and chronic low-grade PJI.

Conclusion

The proposed assay appears to be a reliable and affordable tool for detecting the active MPO in synovial fluid, with promising characteristics of sensitivity and specificity in discriminating both acute and low-grade PJI from AF. Further studies are needed to confirm MPO diagnostic cut-off values and validate their use in the routine clinical practice.

Interleukin-1β Polymorphisms Are Genetic Markers of Susceptibility to Periprosthetic Joint Infection in Total Hip and Knee Arthroplasty

Periprosthetic joint infections (PJIs) are serious complications of prosthetic surgery. The criteria for the diagnosis of PJI integrate clinical and laboratory findings in a complex and sometimes inconclusive workflow. Host immune factors hold potential as diagnostic biomarkers in bone and joint infections. We reported that the humoral pattern-recognition molecule long pentraxin 3 (PTX3) predicts PJI in total hip and knee arthroplasty (THA and TKA, respectively). If and how genetic variation in PTX3 and inflammatory genes that affect its expression (IL-1β, IL-6, IL-10, and IL-17A) contributes to the risk of PJI is unknown. We conducted a case-control study on a Caucasian historic cohort of THA and TKA patients who had prosthesis explant due to PJI (cases) or aseptic complications (controls). Saliva was collected from 93 subjects and used to extract DNA and genotype PTX3, IL-1β, IL-6, IL-10, and IL-17A single-nucleotide polymorphisms (SNPs). Moreover, the concentration of IL-1β, IL-10, and IL-6 was measured in synovial fluid and plasma. No association was found between PTX3 polymorphisms and PJI; however, the AGG haplotype, encompassing rs2853550, rs1143634, and rs1143627 in IL-1β, was linked to the infection (p = 0.017). Also, synovial levels of all inflammatory markers were higher in cases than in controls, and a correlation emerged between synovial concentration of PTX3 and that of IL-1β in cases only (Spearman r = 0.67, p = 0.004). We identified a relationship between rs2853550 and the synovial concentration of IL-1β and PTX3. Our findings suggest that IL-1β SNPs could be used for the early identification of THA and TKA patients with a high risk of infection.

Fracture related Infection - Challenges in definition and diagnosis

In the field of orthopedics and trauma surgery, the rise of periprosthetic joint infections following joint replacement and fracture-related infections (FRI) has become a growing concern. The recent establishment of a definitive definition for FRI aimed to standardize diagnosis and treatment approaches while considering unique aspects of implant-associated infections in the presence of concomitant bone fractures. Diagnosing FRI can be challenging due to the varied clinical symptoms, and confirmatory criteria may not always be evident, necessitating additional diagnostic measures. Blood markers like leukocyte count, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) have limited specificity. Although novel biomarkers such as D-dimer and interleukin-6 (IL-6) show potential, they require further investigation. The use of microbiological diagnostics with tissue samples and sonication has improved pathogen detection. Cross-sectional imaging techniques like CT scans and MRI scans help evaluate bone status, soft tissue infiltration, and abscesses. Nuclear medicine techniques are accurate but may not always be practical in routine clinical practice. Histopathological interpretation for FRI remains less standardized compared to periprosthetic joint infections (PJI). FRI diagnosis requires the identification of visible microorganisms in deep tissue specimens and the quantification of polymorphonuclear neutrophils (PMNs). The defined concept of FRI has opened doors for better diagnostic and treatment approaches. However, challenges persist, especially in preoperative diagnosis, particularly for cases with unclear clinical presentations. Future endeavors aimed at optimizing diagnostic procedures and establishing a histopathological classification for FRI could lead to improved treatment recommendations and outcomes.

Hybrid Impedimetric Biosensors for Express Protein Markers Detection

Impedimetric biosensors represent a powerful and promising tool for studying and monitoring biological processes associated with proteins and can contribute to the development of new approaches in the diagnosis and treatment of diseases. The basic principles, analytical methods, and applications of hybrid impedimetric biosensors for express protein detection in biological fluids are described. The advantages of this type of biosensors, such as simplicity and speed of operation, sensitivity and selectivity of analysis, cost-effectiveness, and an ability to be integrated into hybrid microfluidic systems, are demonstrated. Current challenges and development prospects in this area are analyzed. They include (a) the selection of materials for electrodes and formation of nanostructures on their surface; (b) the development of efficient methods for biorecognition elements' deposition on the electrodes' surface, providing the specificity and sensitivity of biosensing; (c) the reducing of nonspecific binding and interference, which could affect specificity; (d) adapting biosensors to real samples and conditions of operation; (e) expanding the range of detected proteins; and, finally, (f) the development of biosensor integration into large microanalytical system technologies. This review could be useful for researchers working in the field of impedimetric biosensors for protein detection, as well as for those interested in the application of this type of biosensor in biomedical diagnostics.