Diagnostic accuracy of interleukin-6 and procalcitonin in patients with periprosthetic joint infection: a systematic review and meta-analysis

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 value of procalcitonin in patients with periprosthetic joint infection: a diagnostic meta-analysis

Background

The success rate of periprosthetic joint infection (PJI) treatment is still low. Early diagnosis is the key to successful treatment. Therefore, it is necessary to find a biomarker with high sensitivity and specificity. The diagnostic value of serum procalcitonin (PCT) for PJI was systematically evaluated to provide the theoretical basis for clinical diagnosis and treatment in this study.

Methods

We searched the Web of Science, Embase, Cochrane Library, and PubMed for studies that evaluated the diagnostic value of serum PCT for PJI (from the inception of each database until September 2020). Two authors independently screened the literature according to the inclusion and exclusion criteria. The quality of each selected literature was evaluated by using the Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2) tool. RevMan 5.3 software was used for the quality evaluation. The sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were merged by using Meta-DiSc 1.4 software. The area under the curve (AUC) and Q index were calculated after the summary receiver operating characteristic (SROC) was generated. We also performed subgroup analysis.

Results

A total of 621 patients were enrolled in the nine studies. The pooled sensitivity of serum PCT for PJI diagnosis was 0.441 [95% confidence interval (CI), 0.384-0.500], the pooled specificity was 0.852 (95% CI, 0.811-0.888), the pooled PLR was 2.271 (95% CI, 1.808-2.853), the pooled NLR was 0.713 (95% CI, 0.646-0.786), and the pooled DOR was 5.756 (95% CI, 3.673-9.026). The area under SROC (the pooled AUC) was 0.76 (0.72-0.79). Q index was 0.6948.

Conclusion

This study showed that PCT detection of PJI had poor diagnostic accuracy. Hence, the serum PCT is not suitable as a serum marker for PJI diagnosis.

Management of septic arthritis and prosthetic joint infection

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

The Change of Serum Interleukin-6 Fails to Identify Subsequent Periprosthetic Joint Infection in Patients Who Have Two-Stage Revision for Periprosthetic Joint Infection

BACKGROUND

The diagnosis of persistent infection prior to second-stage reimplantation in 2-stage exchanges for periprosthetic joint infection (PJI) can be challenging as there is no optimal diagnostic tool. This study investigates the usefulness of pre-reimplantation serum C-reactive protein (CRP) and interleukin-6 (IL-6) and its change between both stages to identify patients who have subsequent PJI.

METHODS

There were 125 patients who underwent planned 2-stage exchange for chronic knee or hip PJI from a single center retrospectively identified. Patients were included if preoperative CRP and IL-6 were available for both stages. Subsequent PJI was defined as 2 positive microbiological cultures at reimplantation or subsequent surgery or death due to PJI during follow-up.

RESULTS

Prior to reimplantation, the median serum CRP (total knee arthroplasties [TKAs]: 1.0 versus 0.5 mg/dL, P = .028; total hip arthroplasties [THAs]: 1.3 versus 0.5 mg/dL, P = .015) and median IL-6 (TKA: 8.0 versus 6.0 pg/mL, P = .052; THA: 7.0 versus 6.0 pg/mL, P = .239) were higher in patients who had subsequent PJI. The IL-6 and CRP values showed moderate sensitivity (TKA/CRP: 66.7%; THA/CRP: 58.8%; TKA/IL-6: 46.7%; THA/IL-6: 35.3%) and good specificity (TKA/CRP: 66.7%; THA/CRP: 81.0%; TKA/IL-6: 86.3%; THA/IL-6: 83.3%). The change in CRP and IL-6 between the stages did not differ between the groups, respectively.

CONCLUSIONS

Serum CRP and IL-6 show low to moderate sensitivity and good specificity in the diagnosis of subsequent PJI prior to reimplantation, which questions their usefulness as a rule-out test. Furthermore, the change in between stages does not appear to identify subsequent PJI.

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

BACKGROUND

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

RESULTS

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

SIGNIFICANCE

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

Periprosthetic Joint Infection Diagnosis: A Narrative Review

Replacement of native joints aims to restore patients' quality of life by relieving pain and improving joint function. While periprosthetic joint infection (PJI) affects a small percentage of patients, with an estimated incidence of 1-9% following primary total joint replacement, this postoperative complication necessitates a lengthy hospitalisation, extended antibiotic treatment and further surgery. It is highlighted that establishing the correct diagnosis of periprosthetic infections is critical in order for clinicians to avoid unnecessary treatments in patients with aseptic failure. Of note, the PJI diagnosis could not purely rely upon clinical manifestations given the fact that heterogeneity in host factors (e.g., age and comorbidities), variability in infection period, difference in anatomical location of the involved joint and discrepancies in pathogenicity/virulence of the causative organisms may confound the clinical picture. Furthermore, intra-operative contamination is considered to be the main culprit that can result in early or delayed infection, with the hematogenous spread being the most prevalent mode. To elaborate, early and hematogenous infections often start suddenly, whereas chronic late infections are induced by less virulent bacteria and tend to manifest in a more quiescent manner. Last but not least, viruses and fungal microorganisms exert a role in PJI pathogenesis.

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

➤

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.

➤

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.

➤

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.

➤

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.

Procalcitonin as a Predictor of Septic Knee Arthritis: A Retrospective Cohort Study

INTRODUCTION

Differentiating septic arthritis from aseptic arthritis (AA) of the knee is difficult without arthrocentesis. Although procalcitonin (PCT) has shown diagnostic value in identifying bacterial infections, it has not been established as a reliable marker for identifying septic arthritis (SA). Recent studies have shown promise in the use of PCT as a useful systemic marker for identifying septic arthritis versus AA. This observational retrospective review compares PCT with routine inflammatory markers as a tool for differentiating septic arthritis versus AA in patients with acute, atraumatic knee pain.

METHODS

Fifty-three consecutive patients (24 SA, 29 AA) were retrospectively reviewed at one institution with concern for SA. SA was diagnosed based on a physical examination, laboratory markers, and arthrocentesis. Laboratory indices were compared between the septic arthritis and AA groups. Data analysis was conducted to define sensitivity and specificity. Receiver operator characteristic curve analysis and regression were conducted to determine the best marker for acute SA of the knee.

RESULTS

Using multiple logistic regression, bacteremia (OR 6.75 ± 5.75) was determined to be the greatest predictor of SA. On linear regression, concomitant bacteremia (coef 3.07 ± 0.87), SA (coef 2.18 ± 0.70), and the presence of pseudogout crystals (coef 1.80 ± 0.83) on microscopy predicted an increase in PCT. Using a PCT cutoff of 0.25 ng/mL yields a sensitivity of 91.7% and specificity of 55.2% for predicting SA; however, the ideal cutoff in our series was 0.32 ng/mL with a sensitivity of 79.2% and specificity of 72.4%. PCT was superior to the white blood cell count, erythrocyte sedimentation rate, and C-reactive protein in the area under the receiver-operating characteristic curve analysis.

DISCUSSION

Procalcitonin seems to be the most sensitive and specific systemic marker in differentiating septic from AA.

Serum versus synovial fluid interleukin-6 for periprosthetic joint infection diagnosis: a systematic review and meta-analysis of 30 diagnostic test accuracy studies

BACKGROUND

Early and accurate detection of periprosthetic joint infection (PJI) after hip and/or knee arthroplasty remains challenging. This systematic review and meta-analysis of diagnostic test accuracy studies aimed to evaluate the diagnostic accuracy of serum and synovial fluid interleukin (IL)-6 in detecting PJI.

METHODS

We searched 3 databases for studies through December 31, 2021, using medical sub-headings terms and keywords. Studies reported sensitivity and specificity of serum and synovial fluid IL-6 in detecting PJI were considered. We calculated the pooled sensitivity, specificity, positive and negative likelihood ratio, diagnostic odds ratio (DOR), and the area under the summary receiver operating characteristic curve (AUC) to evaluate the diagnostic accuracy of serum and synovial fluid IL-6.

RESULTS

Thirty studies were included. The pooled sensitivity, specificity, positive and negative likelihood ratio, DOR, and AUC of serum IL-6 in detecting PJI were 0.76 (0.69-0.81), 0.88 (0.82-0.92), 6.2 (4.3-9.0), 0.28 (0.22-0.35), 22 (14-36), and 0.88 (0.85-0.91), respectively. However, synovial fluid IL-6 achieved a pooled sensitivity of 0.87 (0.75-0.93), specificity of 0.90 (0.85-0.93), positive and negative likelihood ratio of 8.5 (5.3-13.6) and 0.15 (0.08-0.29), DOR of 57 (21-156), and AUC of 0.94 (0.92-0.96), which were higher than serum IL-6.

CONCLUSIONS

Synovial fluid IL-6 test may be a promising test for PJI after hip and/or knee arthroplasty. However, considering the limited volume of synovial fluid and invasive acquisition of synovial fluid IL-6, serum IL-6 test may be also considered.

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.

Inflammatory blood parameters as prognostic factors for surgical site infection after primary hip or knee arthroplasty: a systematic review protocol

INTRODUCTION

Surgical site infection (SSI) is a potential complication of surgical procedure. SSI after implant surgery is a disaster both for patients and surgeons. Although predictive tools for SSI are available, none of them estimate early infection based on inflammatory blood parameters. The inflammatory process can be measured using several parameters including interleukin-6, C reactive protein, neutrophil to lymphocyte ratio, white cell count, erythrocyte sedimentation rate or procalcitonin. This systematic review aims to determine whether inflammatory blood parameters could be used as significant predictive factors for SSI after primary hip or knee arthroplasty.

METHODS AND ANALYSIS

A systematic review of randomised controlled trials, cross-sectional studies, case-control studies and cohort studies, published in English, will be searched in the following electronic bibliographic databases: MEDLINE, Embase, PubMed, Cochrane Central Register of Controlled Trials and Web of Science. Studies performed in adult patients of all ages who underwent knee or hip arthroplasty, studies containing data on the risk/prognostic factors for preknee or postknee or hip arthroplasty SSI and studies with a minimum follow-up of 30 days after surgery will be included. A standardised form will be used to extract data from the included studies comprising study characteristics, participant characteristics, details of the intervention, study methodology and outcomes. Quality Assessment of Diagnostic Accuracy tool, second version, and Standards for Reporting of Diagnostic Accuracy Studies checklist will be used to assess risk of bias. Heterogeneity will be assessed using Cochran χ² statistic and I² statistics where applicable. Grading of Recommendations Assessment, Development and Evaluation and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance will be used to report findings.

ETHICS AND DISSEMINATION

No ethics approval is required. The findings will be disseminated at national and international scientific sessions, also to be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42020147925.

Procalcitonin for individualizing antibiotic treatment: an update with a focus on COVID-19

Procalcitonin (PCT) is useful for differentiating between viral and bacterial infections and for reducing the unnecessary use of antibiotics. As the rise of antimicrobial resistance reaches “alarming” levels according to the World Health Organization, the importance of using biomarkers, such as PCT to limit unnecessary antibiotic exposure has further increased. Randomized trials in patients with respiratory tract infections have shown that PCT has prognostic implications and its use, embedded in stewardship protocols, leads to reductions in the use of antibiotics in different clinical settings without compromising clinical outcomes. However, available data are heterogeneous and recent trials found no significant benefit. Still, from these trials, we have learned several key considerations for the optimal use of PCT, which depend on the clinical setting, severity of presentation, and pretest probability for bacterial infection. For patients with respiratory infections and sepsis, PCT can be used to determine whether to initiate antimicrobial therapy in low-risk settings and, together with clinical data, whether to discontinue antimicrobial therapy in certain high-risk settings. There is also increasing evidence regarding PCT-guided therapy in patients with coronavirus disease 2019 (COVID-19). This review provides an up-to-date overview of the use of PCT in different clinical settings and diseases, including a discussion about its potential to improve the care of patients with COVID-19.

Phage Therapy for Limb-threatening Prosthetic Knee Klebsiella pneumoniae Infection: Case Report and In Vitro Characterization of Anti-biofilm Activity

BACKGROUND

Prosthetic joint infection (PJI) is a potentially limb-threatening complication of total knee arthroplasty. Phage therapy is a promising strategy to manage such infections including those involving antibiotic-resistant microbes, and to target microbial biofilms. Experience with phage therapy for infections associated with retained hardware is limited. A 62-year-old diabetic man with a history of right total knee arthroplasty 11 years prior who had suffered multiple episodes of prosthetic knee infection despite numerous surgeries and prolonged courses of antibiotics, with progressive clinical worsening and development of severe allergies to antibiotics, had been offered limb amputation for persistent right prosthetic knee infection due to Klebsiella pneumoniae complex. Intravenous phage therapy was initiated as a limb-salvaging intervention.

METHODS

The patient received 40 intravenous doses of a single phage (KpJH46Φ2) targeting his bacterial isolate, alongside continued minocycline (which he had been receiving when he developed increasing pain, swelling, and erythema prior to initiation of phage therapy). Serial cytokine and biomarker measurements were performed before, during, and after treatment. The in vitro anti-biofilm activity of KpJH46Φ2, minocycline and the combination thereof was evaluated against a preformed biofilm of the patient's isolate and determined by safranin staining.

RESULTS

Phage therapy resulted in resolution of local symptoms and signs of infection and recovery of function. The patient did not experience treatment-related adverse effects and remained asymptomatic 34 weeks after completing treatment while still receiving minocycline. A trend in biofilm biomass reduction was noted 22 hours after exposure to KpJH46Φ2 (P = .063). The addition of phage was associated with a satisfactory outcome in this case of intractable biofilm-associated prosthetic knee infection. Pending further studies to assess its efficacy and safety, phage therapy holds promise for treatment of device-associated infections.

Diagnostic value of next-generation sequencing to detect periprosthetic joint infection

Background

We herein compared the diagnostic value of next-generation sequencing (NGS), bacterial culture, and serological biomarkers to detect periprosthetic joint infection (PJI) after joint replacement.

Methods

According to the diagnostic criteria of the Musculoskeletal Infection Society, 35 patients who underwent joint revision surgery were divided into infection (15 cases) and non-infection (20 cases) groups, and were routinely examined preoperatively for erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6), and D-dimer levels. All patients underwent arthrocentesis preoperatively. Synovial fluid was used for white blood cell count, white blood cell classification, bacterial culture, and NGS. Furthermore, we calculated the area under the curve (AUC) of the receiver operating characteristic curve (ROC) for ESR, CRP, PCT, IL-6, and D-dimer. Data were assessed by comparing diagnostic accuracy, sensitivity, and specificity.

Results

Fourteen patients showed positive results by NGS and seven showed positive bacterial culture results in the infection group; further, 18 showed negative results by NGS in the non-infection group. The AUC of ESR, D-dimer, CRP, IL-6, and PCT was 0.667, 0.572, 0.827, 0.767, and 0.808, respectively. The accuracy of NGS, bacterial culture, CRP, IL-6, and PCT was 0.91, 0.74, 0.77, 0.74, and 0.83, respectively. When comparing NGS with CRP, IL-6, PCT, and bacterial culture, differences in overall test results and those in sensitivity were statistically significant, and compared with CRP, differences in specificity were also statistically significant. In comparison with IL-6, PCT, and bacterial culture, the specificity of NGS was statistically insignificant.

Conclusions

Our results indicated that NGS had higher accuracy and sensitivity than the bacterial culture method and commonly used serological biomarkers for diagnosing PJI.

Should all hip and knee prosthetic joints be aspirated prior to revision surgery?

AIMS

It is essential to exclude a periprosthetic joint infection (PJI) prior to revision surgery. It is recommended to routinely aspirate the joint before surgery. However, this may not be necessary in a subgroup of patients. The aim of our study was to investigate if specific clinical and implant characteristics could be identified to rule out a PJI prior to revision surgery.

METHODS

We retrospectively evaluated clinical and implant characteristics of patients who underwent a hip or knee revision surgery between October 2015 and October 2018. Patients were diagnosed with a PJI according to the MSIS diagnostic criteria.

RESULTS

A total of 156 patients were analyzed, including 107 implants that were revised because of prosthetic loosening and 49 because of mechanical failure (i.e. instability, malalignment or malpositioning). No PJI was diagnosed in the group with mechanical failure. In the prosthetic loosening group, 20 of 107 were diagnosed with a PJI (19%). Although there was a significantly lower chance of having a PJI with an implant age of > 5 years combined with a CRP < 5 mg/L, an infection was still present in 3 out of 39 cases (8%).

CONCLUSION

Implants with solely mechanical failure without signs of loosening and low inflammatory parameters probably do not require a synovial fluid aspiration. These results need to be confirmed in a larger cohort of patients. In case of prosthetic loosening, all joints need to be aspirated before surgery as no specific characteristic could be identified to rule out an infection.

Circulating D-Dimer versus Fibrinogen in the Diagnosis of Peri-Prosthetic Joint Infection: A Meta-Analysis

Background: Circulating D-dimer and fibrinogen are both emerging as promising biomarkers for the diagnosis of peri-prosthetic joint infection (PJI), but their clinical values still remain disputable. This study aims to evaluate and compare the accuracy of circulating D-dimer and fibrinogen in the diagnosis of suspected PJI. Methods: We conducted a comprehensive literature search in PubMed, EMBASE, and the Cochrane Library to retrieve diagnostic accuracy studies in which PJI was investigated with circulating D-dimer or fibrinogen from the time of database inception to August 1, 2019. The pooled sensitivity, specificity, likelihood ratios and diagnostic odds ratio (DOR), summary receiver operating characteristic (sROC) curves, and area under the sROC curve (AUC) were constructed using a meta-analysis framework. Results: Seven eligible studies (1,374 patients) were included in the quantitative analysis. The mean levels of circulating D-dimer and fibrinogen were all significantly higher in patients with PJI. The plasma fibrinogen illustrated relatively higher sensitivity (0.84, 95% confidence interval [CI]: 0.78-0.98) and specificity (0.80, 95% CI: 0.76-0.84) than circulating D-dimer (0.74, 95% CI: 0.69-0.78; 0.66, 95% CI: 0.62-0.69, respectively) for the diagnosis of PJI. The pooled DOR of D-dimer, fibrinogen, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) to diagnose PJI was 7.00 (95% CI, 2.50-19.59), 12.40 (95% CI, 5.85 to 26.28), 10.71 (95% CI, 7.76 to 14.78) and 16.22 (95% CI 11.71-22.46), respectively, while the pooled AUC was 0.84 (95% CI, 0.77-0.90), 0.87 (95% CI, 0.85-0.89), 0.82 (95% CI, 0.78-0.85) and 0.87 (95% CI, 0.86-0.88), respectively. Conclusions: This meta-analysis reveals that it could be concluded that plasma fibrinogen is an excellent biomarker for diagnosing PJI, comparable to serum CRP and ESR, while the diagnostic value of circulating D-dimer is only moderate. Large-scale, prospective studies are still needed to confirm current findings.

Soluble Pecam-1 as a Biomarker in Periprosthetic Joint Infection

A reliable workup with regard to a single diagnostic marker indicating periprosthetic joint infection (PJI) with sufficient sensitivity and specificity is still missing. The immunologically reactive molecule Pecam-1 is shed from the T-cell surface upon activation via proinflammatory signaling, e.g., triggered by specific pathogens. We hypothesized that soluble Pecam-1 (sPecam-1) can hence function as a biomarker of PJI. Fifty-eight patients were prospectively enrolled and assigned to one of the respective treatment groups (native knees prior to surgery, aseptic, and septic total knee arthroplasty (TKA) revision surgeries). Via synovial sample acquisition and ELISA testing, a database on local sPecam-1 levels was established. We observed a significantly larger quantity of sPecam-1 in septic (n = 22) compared to aseptic TKA revision surgeries (n = 20, p ≤ 0.001). Furthermore, a significantly larger amount of sPecam-1 was found in septic and aseptic revisions compared to native joints (n = 16, p ≤ 0.001). Benchmarking it to the gold standard showed a high predictive power for the detection of PJI. Local sPecam-1 levels correlated to the infection status of the implant, and thus bear a strong potential to act as a biomarker of PJI. While a clear role of sPecam-1 in infection could be demonstrated, the underlying mechanism of the molecule’s natural function needs to be further unraveled.

Next-generation sequencing not superior to culture in periprosthetic joint infection diagnosis

AIMS

Use of molecular sequencing methods in periprosthetic joint infection (PJI) diagnosis and organism identification have gained popularity. Next-generation sequencing (NGS) is a potentially powerful tool that is now commercially available. The purpose of this study was to compare the diagnostic accuracy of NGS, polymerase chain reaction (PCR), conventional culture, the Musculoskeletal Infection Society (MSIS) criteria, and the recently proposed criteria by Parvizi et al in the diagnosis of PJI.

METHODS

In this retrospective study, aspirates or tissue samples were collected in 30 revision and 86 primary arthroplasties for routine diagnostic investigation for PJI and sent to the laboratory for NGS and PCR. Concordance along with statistical differences between diagnostic studies were calculated.

RESULTS

Using the MSIS criteria to diagnose PJI as the reference standard, the sensitivity and specificity of NGS were 60.9% and 89.9%, respectively, while culture resulted in sensitivity of 76.9% and specificity of 95.3%. PCR had a low sensitivity of 18.4%. There was no significant difference based on sample collection method (tissue swab or synovial fluid) (p = 0.760). There were 11 samples that were culture-positive and NGS-negative, of which eight met MSIS criteria for diagnosing infection.

CONCLUSION

In our series, NGS did not provide superior sensitivity or specificity results compared to culture. PCR has little utility as a standalone test for PJI diagnosis with a sensitivity of only 18.4%. Currently, several laboratory tests for PJI diagnosis should be obtained along with the overall clinical picture to help guide decision-making for PJI treatment. Cite this article: Bone Joint J 2021;103-B(1):26-31.

The EBJIS definition of periprosthetic joint infection

Aims

The diagnosis of periprosthetic joint infection (PJI) can be difficult. All current diagnostic tests have problems with accuracy and interpretation of results. Many new tests have been proposed, but there is no consensus on the place of many of these in the diagnostic pathway. Previous attempts to develop a definition of PJI have not been universally accepted and there remains no reference standard definition.

Methods

This paper reports the outcome of a project developed by the European Bone and Joint Infection Society (EBJIS), and supported by the Musculoskeletal Infection Society (MSIS) and the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Implant-Associated Infections (ESGIAI). It comprised a comprehensive review of the literature, open discussion with Society members and conference delegates, and an expert panel assessment of the results to produce the final guidance.

Results

This process evolved a three-level approach to the diagnostic continuum, resulting in a definition set and guidance, which has been fully endorsed by EBJIS, MSIS, and ESGIAI.

Conclusion

The definition presents a novel three-level approach to diagnosis, based on the most robust evidence, which will be useful to clinicians in daily practice.

Cite this article: Bone Joint J 2021;103-B(1):18–25.

Plasma fibrinogen in the diagnosis of periprosthetic joint infection

Periprosthetic joint infections (PJIs) have become the most catastrophic complication for patients after arthroplasty. Although previous studies have found that many biomarkers have good performance for diagnosing PJI, early diagnosis remains challenging and a gold standard is lacking. This study aimed to investigate the diagnostic accuracy of plasma fibrinogen (FIB) in detecting PJI compared to other traditional biomarks (CRP, WBC and ESR). A total of 156 patients (including 57 PJI and 99 non-PJI patients) who underwent revision arthroplasty were retrospectively reviewed from 01/2014 to 01/2020. The diagnostic criteria of PJI were mainly based on the definition from the evidence-based definition for periprosthetic joint infection in 2018. The optimal plasma FIB predictive cutoff was 4.20 g/L, the sensitivity of the plasma fibrinogen was 0.860, the specificity was 0.900, the positive predictive value (PPV) was 0.831, and the negative predictive value (NPV) was 0.908. The area under the curve (AUC) value of plasma fibrinogen was 0.916 (95% CI 0.869-0.964), and the CRP, ESR and WBC levels had AUCs of 0.901, 0.822 and 0.647, respectively. Plasma FIB demonstrated better diagnostic strength compared with that of other serum biomarkers before revision arthroplasty. It represents a new horizon for the diagnosis of PJI due to the diagnosis values and cost-effective features.

Commercially Available Polymerase Chain Reaction Has Minimal Utility in the Diagnosis of Periprosthetic Joint Infection

The use of genetic sequencing modalities in the diagnosis of periprosthetic joint infection (PJI) and the identification of organisms has gained popularity recently. Polymerase chain reaction (PCR) offers timely results for common organisms. The purpose of this study was to compare the accuracy of broad-range PCR, conventional culture, the Musculoskeletal Infection Society (MSIS) criteria, and the recently proposed criteria by Parvizi et al in the diagnosis of PJI. In this retrospective study, aspirate or tissue samples were collected in 104 revision and 86 primary arthroplasties for routine diagnostic workup for PJI and sent to the laboratory for PCR. Concordance along with statistical differences between diagnostic studies were calculated using chi-square test for categorical data. On comparison with the MSIS criteria, concordance was significantly lower for PCR at 64.7% compared with 86.3% for culture (P<.001). There was no significant difference based on diagnosis of prior infection (P=.706) or sample collection method (tissue swab or synovial fluid) (P=.316). Of the 87 patients who met MSIS criteria, only 20 (23.0%) PCR samples had an organism identified. In this series, PCR had little utility as a stand-alone test for the diagnosis of PJI, with a sensitivity of only 23.0% when using MSIS criteria as the gold standard. Polymerase chain reaction also appears to be significantly less accurate than culture in the diagnosis of PJI. Currently, several laboratory tests used for either criteria for PJI diagnosis should be obtained along with the overall clinical picture to help guide decision-making for PJI treatment. [Orthopedics. 2020;43(6):333-338.].

Serum globulin and albumin to globulin ratio as potential diagnostic biomarkers for periprosthetic joint infection: a retrospective review

Background

Periprosthetic joint infection (PJI) has been increasingly documented; however, its preoperative accurate diagnosis remains challenging. Furthermore, there is a dire need to identify appropriate and effective biomarkers. We aimed to evaluate the relationship between globulin, albumin to globulin (A/G) ratio, and development of PJI in patients undergoing revision total joint arthroplasty (TJA).

Methods

A retrospective study was conducted on patients who had undergone revision TJA between 2011 and 2018 (89 with aseptic mechanic failure and 38 with PJI). The serum proteins were explored using univariate analysis followed by multivariate logistic regression. The diagnostic performance of these proteins was assessed by the receiver operating characteristic (ROC) curve.

Results

Higher globulin levels (odds ratio [OR], 1.239; P < 0.001) and lower A/G ratio (OR, 0.007; P < 0.001) were strongly associated with the risk of PJI. ROC curve analysis demonstrated reasonable diagnostic performance for globulin (area under the curve [AUC], 0.77; sensitivity, 78.95%; and specificity, 69.66%) and A/G ratio (AUC, 0.779; sensitivity, 65.79%; and specificity, 78.65%).

Conclusions

Both globulin and A/G ratio were associated with PJI and may serve as potential adjuvant biomarkers in the diagnosis of PJI.

Is combining serum interleukin-6 and C-reactive protein a reliable diagnostic tool in periprosthetic joint infections?

BACKGROUND

Because there is no single gold standard method for the diagnosis of periprosthetic joint infection (PJI), the combination of valuable methods to evaluate infection appears to achieve a better diagnostic result. The objective of the present study was to evaluate the diagnostic value of serum interleukin (IL)-6 and C-reactive protein (CRP) for the diagnosis of PJI.

METHODS

PubMed, Embase, and the Web of Science databases were searched for articles describing PJI diagnosis using serum IL-6 and CRP published between January 1990 and December 2019.

RESULTS

Eight studies were included in the meta-analysis. The pooled sensitivity was 0.84 (95% confidence interval [CI], 0.80-0.88) for the combined method (serum IL-6 and CRP) in series and parallel approaches, 0.87 (95% CI, 0.82-0.90) for IL-6, and 0.84 (95% CI, 0.79-0.88) for CRP. The pooled specificity was 0.85 (95% CI, 0.82-0.88) for the combined method, 0.83 (95% CI, 0.79-0.87) for IL-6, and 0.83 (95% CI, 0.79-0.87) for CRP. The combined method had the highest value for the area under the curve (0.9453), followed by IL-6 (0.9237) and CRP (0.9074). Subgroup analyses showed that the sensitivity of the combined method in parallel tests was higher than that in IL-6 or CRP (94% vs. 89% and 84%, respectively). Serial testing of the combined method showed increased specificity compared to a single indicator (96% vs. 83% and 80%).

CONCLUSION

The combination of serum IL-6 and CRP was a reliable tool for the diagnosis of periprosthetic hip and knee infection, demonstrating a better diagnostic accuracy than single marker analysis.

Comparing the Diagnostic Value of Serum D-Dimer to CRP and IL-6 in the Diagnosis of Chronic Prosthetic Joint Infection

Introduction: D-dimer is a diagnostic criterion for periprosthetic joint infection (PJI) of the Musculoskeletal Infection Society (MSIS) in 2018. The aim of this study was to evaluate the serum D-dimer values in comparison to C-reactive protein (CRP) and interleukin-6 (IL-6) for the diagnosis of PJI. Materials and Methods: We included 119 patients (50 women, 69 men; 71 knees, 48 hips) undergoing revision arthroplasty with preoperative assessment of CRP, IL-6, and serum D-dimer. Cases were classified as infected or aseptic based on the MSIS criteria of 2018. Receiver operating curves and Youden’s index were used to define an ideal cut-off value and sensitivity and specificity for the individual parameters, and respective combinations were calculated using cross-tables. Results: The median D-dimer level (2320 vs. 1105 ng/mL; p < 0.001), the median CRP level (4.0 vs. 0.5 mg/dL; p < 0.001), and the median IL-6 level (21.0 vs. 5.0 pg/mL; p < 0.001) were significantly higher in the group of PJI compared to the group with aseptic failure. The calculated optimal cut-off values were 2750 ng/mL (AUC 0.767) for D-dimer, 1.2 mg/dL (AUC 0.914) for CRP, and 10.0 pg/mL (AUC 0.849) for IL-6. D-dimer showed a sensitivity of 38% and specificity of 94%, whereas the CRP and IL-6 had sensitivities of 88% and 76%, and specificities of 87% and 92%, respectively. Conclusion: In comparison with CRP and IL-6, serum D-dimer showed low sensitivity and specificity in our cohort. While CRP and IL-6 combination had the highest sensitivity, a combination of Il-6 and D-dimer or CRP and IL-6 had the highest specificity.

Clinical outcome of different skin closure in total-knee arthroplasty: running subcuticular closure vs intermittent closure: A retrospective study

An intermittent closure with silk suture is routinely used for closing different surgical wounds. However, subcuticular closure with absorbable sutures has gained considerable attention due to convenience and better cosmetic appearance.To compare the clinical outcomes and risk of surgical-site infection of subcuticular and intermittent closure after total-knee arthroplasty (TKA), 106 patients that underwent TKA between January 2017 to June 2019 at the Department of Orthopedics in Xiangya Hospital of Centre South University were retrospectively assessed. Forty-three had received running subcuticular closure (group A) and 58 underwent intermittent closure (group B). The Knee Society score was measured before and 6 months after operation. Inflammation markers including the serum levels of procalcitonin, interleukin-6, and C-reactive protein, and the erythrocyte sedimentation rate were evaluated before operation, 1 day after and 1 month after operation. Patient satisfaction with the closure was evaluated using the Likert scale at the last follow-up.No significant difference was seen in the 6-month postoperative Knee Society score, or in the 1-day and 6-month postoperative inflammation marker levels between both groups (P > .05). Likert scores were higher in group A compared to group B (4.0 ± 1.0 vs 3.6 ± 1.2, P < .05).Running subcuticular closure after TKA results in a better appearance compared to intermittent closure, although neither method has an advantage in terms of efficacy and risk of infection.

Combined serum biomarker analysis shows no benefit in the diagnosis of periprosthetic joint infection

Purpose

In many cases, the diagnosis of a periprosthetic joint infection (PJI) consisting of the clinical appearance, laboratory tests, and other diagnostic tools remains a difficult task. Single serum biomarkers are easy to collect, are suitable for periodical assessment, and are a crucial tool in PJI diagnosis, but limited sensitivity or specificity is reported in literature. The aim of this study was to combine the best-performing single serum biomarkers into a multi-biomarker model aiming to improve the diagnostic properties.

Methods

Within a 27-month period, 124 surgical procedures (aseptic or septic revision total knee arthroplasty (TKA) or total hip arthroplasty (THA)) were prospectively included. The serum leukocyte count, C-reactive protein (CRP), interleukin-6, procalcitonin, interferon alpha, and fibrinogen were assessed 1 day prior to surgery. Logistic regression with lasso-regularization was used for the biomarkers and all their ratios. After randomly splitting the data into a training (75%) and a test set (25%), the multi-biomarker model was calculated and validated in a cross-validation approach.

Results

CRP (AUC 0.91, specificity 0.67, sensitivity 0.90, p value 0.03) and fibrinogen (AUC 0.93, specificity 0.73, sensitivity 0.94, p value 0.02) had the best single-biomarker performances. The multi-biomarker model including fibrinogen, CRP, the ratio of fibrinogen to CRP, and the ratio of serum thrombocytes to CRP showed a similar performance (AUC 0.95, specificity 0.91, sensitivity 0.72, p value 0.01).

Conclusion

In this study, multiple biomarkers were tested for their diagnostic performance, with CRP and fibrinogen showing the best results regarding the AUC, accuracy, sensitivity, and specificity. It was not possible to further increase the diagnostic accuracy by combining multiple biomarkers using sophisticated statistical methods.

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

Background

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

Methods

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

Results

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

Conclusion

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

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

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

Normal trajectory of Interleukin-6 and C-reactive protein in the perioperative period of total knee arthroplasty under an enhanced recovery after surgery scenario

Background

We designed the current study to understand the normal trajectories of interleukin-6 (IL-6) and C-reactive protein (CRP) in the immediate hours and days after primary total knee arthroplasty (TKA) under the management of an enhanced recovery after surgery (ERAS) protocol and examined whether one or the other returned to normal more quickly.

Methods

In this prospective cross-sectional study, we examined the plasma IL-6 and CRP levels in 100 patients undergoing primary TKA at the following time points: 12 h preoperatively as well as postoperatively 12 h, 48 h, 3 days and 2 weeks. Patients were followed up for 1 year to monitor the postoperative complications, especially the infection.

Results

IL-6 peaked at 48 h postoperatively. Then IL-6 started to decline at 3 days postoperatively and went back to baseline level at 2 weeks (p = 0.950). CRP peaked at 3 days postoperatively. At 2 weeks, CRP declined to a normal range, without being significantly different from the baseline level (p = 0.816).

Conclusion

We found that under the ERAS scenario, the postoperative peak of IL-6 and CRP was deferred compared with previous studies. Compared to IL-6, CRP showed a gradual rise after surgery. Both of these two biomarkers returned to normal under the ERAS scenario. Future multiple-center studies with larger sample size can help define the thresholds of IL-6 and CRP for periprosthetic joint infection (PJI) early diagnosis. With these reference data, a clinician can make a quicker decision to perform aspiration to diagnose early PJI and benefits more patients.

Is Procalcitonin (PCT) a reliable biomarker for preoperative diagnosing of low grade periprosthetic joint infection? A prospective study

BACKGROUND

Since a "gold-standard" is missing, diagnosing periprosthetic joint infection (PJI) remains a challenge in orthopedic surgery. The purpose of this study was to evaluate the accuracy of serum and synovial fluid Procalcitonin (S-PCT and SF-PCT) as a diagnostic parameter and to compare it to the biomarkers recommended in the 2018 Definition of periprosthetic hip and knee infection.

METHODS

Between August 2018 and July 2019, a prospective cohort study was conducted in 70 patients with painful hip, shoulder and knee arthroplasty. Besides medical history, clinical and laboratory data was gathered. PJI was diagnosed based on the 2018 Definition of periprosthetic hip and knee infection. Preoperative blood and synovial joint fluid were taken for PCT measurement. S-PCT and SF-PCT levels were measured using standard quantitative PCT enzyme immunoassays.

RESULTS

Twenty three patients (33%) were classified as the PJI group and fourty seven patient (67%) as the aseptic group. The mean levels of S-PCT were significantly (p <  0.001) higher in the PJI group than those in the aseptic group (PJI 0.05 ± 0.21 ng/mL (0.0-1.03) vs. aseptic 0.02 ± 0.03 ng/mL (0.0-0.18)). In synovial fluid, the mean PCT values in the aseptic group were significantly higher (p <  0.001) than those of PJI group (PJI 2.7 ± 1.4 ng/mL (0.53-9.7) vs. aseptic 8.7 ± 2.5 ng/mL (0.25-87.9)). S- PCT, with a cut-off level of 0.5 ng/mL, had a sensitivity of 13.0% and a specificity of 91.0%. SF-PCT, with a cut-off level of 5.0 ng/mL, had a sensitivity of 13.0% and a specificity of 52.0%.

CONCLUSION

S-PCT and SF-PCT appeared to be no reliable biomarkers in the differential diagnosis of PJI from aseptic loosening in total joint arthroplasty.

Risk factors, diagnosis and management of prosthetic joint infection after total hip arthroplasty

Introduction: Although a relatively rare complication, the incidence and prevalence of prosthetic joint infection (PJI) is certainly rising. This is mainly due to the number of arthroplasties performed each year and our ability to capture more cases. There is currently no consensus in the optimal diagnosis and management of the infected total hip arthroplasty. Various management techniques have been described in literature.Areas covered: We discuss and summarize the literature in diagnosing prosthetic joint infection (PJI) including next-generation sequencing. An in-depth critical analysis of the biomarkers and the novel tests available in the market is reviewed including the evolving nature of the diagnostic criteria for PJI. The key issues in managing infected THA are identified.Expert commentary: The senior authors' expert opinion on diagnostic criteria is discussed. We also stress the importance of tissue/fluid analysis of microbiology and histology being key to diagnosis of PJI. The indications of one-stage versus two-stage revision arthroplasty is examined, including techniques for successful one-stage revision.

Culture-negative periprosthetic joint infections

Culture-negative periprosthetic joint infections (CN-PJI) pose a significant challenge in terms of diagnosis and management. The reported incidence of CN-PJI is reported to be between 7% and 15%.

Fungi and mycobacterium are thought to be responsible for over 85% of such cases with more fastidious bacteria accounting for the rest.

With the advent of polymerase chain reaction, mass spectrometry and next generation sequencing, identifying the causative organism(s) may become easier but such techniques are not readily available and are very costly.

There are a number of more straightforward and relatively low-cost methods to help surgeons maximize the chances of diagnosing a PJI and identify the organisms responsible.

This review article summarizes the main diagnostic tests currently available as well as providing a simple diagnostic clinical algorithm for CN-PJI.

Cite this article: EFORT Open Rev 2019;4:585-594. DOI: 10.1302/2058-5241.4.180067

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

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

Laboratory diagnosis of Prosthetic Joint Infections: Current concepts and present status

Prosthetic joint infection (PJI) is a challenging complication of total joint arthroplasty for both a microbiologist and an Arthroplasty surgeon with respect to diagnosis and management. The various investigations used for diagnosis of PJI based on different reference criteria have their own fallacies. Amongst the newer biomarkers evaluated to strengthen the diagnosis of PJI, Alpha defensins has been found to be a useful synovial fluid biomarker. In this review, we have discussed the various laboratory investigations, their benefits and shortcomings for the diagnosis of PJI. Other newer diagnostic methods like molecular methods and modified culture techniques to increase the performance characteristics for the diagnosis of PJI have also been presented.