Role of core biopsy in diagnosing infection before revision hip arthroplasty

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.

The synovial fluid calprotectin lateral flow test for the diagnosis of chronic prosthetic joint infection in failed primary and revision total hip and knee arthroplasty

PURPOSE

The diagnostic criteria of prosthetic joint infection (PJI) recommended by the most commonly used diagnostic algorithms can be obscured or distorted by other inflammatory processes or aseptic pathology. Furthermore, the most reliable diagnostic criteria are garnered during revision surgery. A robust, reliable addition to the preoperative diagnostic cascade is warranted. Calprotectin has been shown to be an excellent diagnostic marker for PJI. In this study, we aimed to evaluate a lateral flow test (LFT) in the challenging patient cohort of a national referral centre for revision arthroplasty.

METHODS

Beginning in March 2019, we prospectively included patients scheduled for arthroplasty exchange of a total hip (THA) or knee arthroplasty (TKA). Synovial fluid samples were collected intra-operatively. We used the International Consensus Meeting of 2018 (ICM) score as the gold standard. We then compared the pre-operative ICM score with the LFT result to calculate its diagnostic accuracy as a standalone pre-operative marker and in combination with the ICM score as part of an expanded diagnostic workup.

RESULTS

A total of 137 patients with a mean age of 67 (± 13) years with 53 THA and 84 TKA were included. Ninety-nine patients (72.8%) were not infected, 34 (25.0) were infected, and four (2.9%) had an inconclusive final score and could not be classified after surgery. The calprotectin LFT had a sensitivity (95% confidence interval) of 0.94 (0.80-0.99) and a specificity of 0.87 (0.79-0.93). The area under the receiver operating characteristic curve (AUC) for the calprotectin LFT was 0.94 (0.89-0.99). In nine cases with an inconclusive pre-operative ICM score, the calprotectin LFT would have led to the correct diagnosis of PJI.

CONCLUSIONS

The synovial fluid calprotectin LFT shows excellent diagnostic metrics both as a rule-in and a rule-out test, even in a challenging patient cohort with cases of severe osteolysis, wear disease, numerous preceding surgeries, and poor soft tissue conditions, which can impair the common diagnostic criteria. As it is available pre-operatively, this test might prove to be a very useful addition to the diagnostic algorithm.

Diagnostic utility of open biopsy in patients with two culture-negative aspirations in the diagnostic work-up of periprosthetic joint infection

INTRODUCTION

Different approaches have been proposed for bacterial identification in patients with a suspected periprosthetic joint infection (PJI). If a one-stage procedure is considered, a higher rate of preoperative bacterial identification can be achieved if biopsy is included in the diagnostic work-up. The performance of open biopsy (OB) in the context of PJI has not been clearly determined yet. The purpose of this study was to determine the value of an OB added to two consecutive culture-negative joint aspirations during PJI workup.

MATERIALS AND METHODS

We retrospectively analyzed the OB data from a single institution. Patients under PJI work-up of the hip or knee with two culture-negative periprosthetic aspirations who underwent OB were included. Sensitivity and specificity were calculated using the musculoskeletal infection society (MSIS) criteria as gold standard. Patients undergoing urgent irrigation and debridement and patients with history of surgery to the affected joint in the prior 6 weeks were excluded.

RESULTS

126 patients were included in this study. 62 (49.2%) patients had prior revisions, 48 of them due to PJI. The sensitivity and specificity of OB was 69.4% and 89.1%, respectively. The OB procedure led to the identification of the causative germ in 50 out of 126 (40%) cases so they could undergo one-stage (septic) exchange.

CONCLUSION

The OB is a valuable resource if preoperative synovial fluid cultures are negative, a high suspicion of infection persists and a one-stage procedure is preferred. It intends bacteria identification and allows surgeons to evaluate prosthetic complications for further surgical procedures.

Reliable Diagnostic Tests and Thresholds for Preoperative Diagnosis of Non-Inflammatory Arthritis Periprosthetic Joint Infection: A Meta-analysis and Systematic Review

Objective

The current diagnostic criteria for periprosthetic joint infection (PJI) are diverse and controversial, leading to delayed diagnosis. This study aimed to evaluate and unify their diagnostic accuracy and the threshold selection of serum and synovial routine tests for PJI at an early stage.

Methods

We searched the MEDLINE and Embase databases for retrospective or prospective studies which reported preoperative‐available assays (serum, synovial, or culture tests) for the diagnosis of chronic PJI among inflammatory arthritis (IA) or non‐IA populations from January 1, 2000 to June 30, 2022. Threshold effective analysis was performed on synovial polymorphonuclear neutrophils (PMN%), synovial white blood cell (WBC), serum C‐reactive protein (CRP), and erythrocyte sedimentation rate (ESR) to find the relevant cut‐offs.

Results

Two hundred and sixteen studies and information from 45,316 individuals were included in the final analysis. Synovial laboratory‐based α‐defensin and calprotectin had the best comprehensive sensitivity (0.91 [0.86–0.94], 0.95 [0.88–0.98]) and specificity (0.96 [0.94‐0.97], 0.95 [0.89–0.98]) values. According to the threshold effect analysis, the recommended cut‐offs are 70% (sensitivity 0.89 [0.85–0.92], specificity 0.90 [0.87–0.93]), 4100/μL (sensitivity 0.90 [0.87–0.93], specificity 0.97 [0.93–0.98]), 13.5 mg/L (sensitivity 0.84 [0.78–0.89], specificity 0.83 [0.73–0.89]), and 30 mm/h (sensitivity 0.79 [0.74–0.83], specificity 0.78 [0.72–0.83]) for synovial PMN%, synovial WBC, serum CRP, and ESR, respectively, and tests seem to be more reliable among non‐IA patients.

Conclusions

The laboratory‐based synovial α‐defensin and synovial calprotectin are the two best independent preoperative diagnostic tests for PJI. A cut off of 70% for synovial PMN% and tighter cut‐offs for synovial WBC and serum CRP could have a better diagnostic accuracy for non‐IA patients with chronic PJI.

ANALYSIS OF TISSUE BIOPSY AND JOINT ASPIRATION IN THE DIAGNOSIS OF PERIPROSTHETIC HIP INFECTIONS: CROSS-SECTIONAL STUDY

Objective:

To evaluate sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of preoperative joint aspiration (PJA) and periarticular tissue percutaneous biopsy (PTPB), as well as their combination, in the diagnosis of infection after total hip arthroplasty.

Methods:

This cross-sectional study (Level of Evidence II) was conducted with prospective data on 29 patients submitted to PJA with PTPB at the National Institute of Orthopedics and Traumatology from September 2015 to January 2016. Specimens obtained during the procedures underwent microbiological analyses, and the results were compared with those obtained in subsequent revision arthroplasty surgeries.

Results:

PJA, PTPB, and their combination reached values of 78%, 73%, 89% for sensitivity, respectively; 72%, 90%, 94% for specificity; and 76%, 80%, 90% for accuracy.

Conclusions:

PJA combined with PTPB was sensitive, specific, and effective in diagnosing periprosthetic hip infection.Level of Evidence II, Prospective Cross-Sectional Study

[Diagnosis of periprosthetic joint infection : Development of an evidence-based algorithm by the work group of implant-associated infection of the AE-(German Society for Arthroplasty)]

Hintergrund

Die Behandlung periprothetischer Infektionen (PPI) ist eine der größten Herausforderungen im Bereich der Endoprothetik. Der möglichst sichere Ausschluss oder die Bestätigung einer periprothetischen Infektion ist die Voraussetzung für jede Revisionsoperation und kann für den behandelnden Orthopäden und Unfallchirurgen eine große Herausforderung darstellen. Eine sichere evidenzbasierte präoperative Diagnostik ist im Sinne des Patienten notwendig, um einerseits eine periprothetische Infektion zu erkennen sowie die entsprechende chirurgische und antibiotische Therapie zu planen und andererseits unnötige zweizeitige Wechsel zu vermeiden.

Ziel der Arbeit

Ziel ist es, ein evidenzbasiertes problem- und prioritätenbasiertes Vorgehen zu entwickeln und dies in einem transparenten und standardisierten Algorithmus zusammenzufassen.

Methode

Durch systematische Literaturrecherche wurden relevante Arbeiten identifiziert und im Rahmen von Expertenrunden bewertet. Nach Extraktion der Daten erfolgte die Berechnung von Sensitivität, Spezifität, positiver und negativer Likelihood-Ratio sowie positiver und negativer prädiktiver Werte. Im Rahmen von 4 Treffen wurden die entsprechenden Studien der Arbeitsgruppe für implantatassoziierte Infektionen präsentiert und analog zu Standard-Delphi-Runden durch die einzelnen Experten bearbeitet und bewertet. Gemäß der Prioritätenliste der Expertenrunde erfolgte die Entwicklung eines zur ISO (International Organization for Standardisation) konformen Algorithmus.

Ergebnisse

Der entwickelte Algorithmus ist eine Abfolge von evidenzbasierten Prozessen gemäß der verwendeten ISO-Norm. Gemäß der durch die Expertenrunde priorisierten Haupt- und Nebenkriterien erfolgte die Entwicklung logisch strukturiert und problemorientiert.

Schlussfolgerung

Der Ausschluss einer periprothetischen Infektion ist von enormer Bedeutung vor einer Revisionsoperation und entscheidet in vielen Fällen über den Erfolg und die Invasivität der Operation. Die Diagnose „periprothetische Infektion“ erfordert eine substanzielle Veränderung der therapeutischen Strategie. Der durch die Arbeitsgruppe entwickelte Algorithmus fasst Positionen aus der aktuellen Literatur und spezielle Expertenmeinungen zusammen, dies ermöglicht einen transparenten diagnostischen Ansatz im Sinne einer Standard Operation Procedure.

Single vs 2-Stage Revision for the Treatment of Periprosthetic Joint Infection

Periprosthetic joint infection (PJI) is one of the most devastating complications following total joint arthroplasty, accounting for a projected 10,000 revision surgeries per year by 2030. Chronic PJI is complicated by the presence of bacterial biofilm, requiring removal of components, thorough debridement, and administration of antibiotics for effective eradication. Chronic PJI is currently managed with single-stage or 2-stage revision surgery. To date, there are no randomized, prospective studies available evaluating eradication rates and functional outcomes between the 2 techniques. In this review, both treatment options are described with the most current literature to guide effective surgical decision-making that is cost-effective while decreasing patient morbidity.

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.

Puncture Protocol in the Diagnostic Work-Up of a Suspected Chronic Prosthetic Joint Infection of the Hip

BACKGROUND

Diagnosing a chronic prosthetic joint infection (PJI) can be challenging. We hypothesized that obtaining preoperative tissue samples for culture in hip arthroplasty will increase the likelihood of diagnosing an infection before revision surgery. The aim of this cohort study was to determine the diagnostic accuracy of 2 tissue acquiring biopsy strategies to diagnose a PJI.

METHODS

Patients with a painful hip arthroplasty, in which a chronic PJI was suspected, were included. Tissue samples were obtained either by ultrasound guidance with a 16-Gauge needle (2012-2013) or in the operating room with a thick-bore needle (2013-2016). Revision surgery tissue biopsies were used as the gold standard. Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio were calculated.

RESULTS

A total of 16 patients in the ultrasound cohort and 29 patients in the surgical cohort were included. Thirty-one percent (n = 14) were finally diagnosed with a PJI. The addition of thick bore needle tissue biopsies resulted in 9% more diagnosed PJIs compared with synovial fluid alone. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio was 33%, 85%, 33%, 85%, 2.2, and 0.8, respectively, for the ultrasound-guided biopsy cohort and 82%, 100%, 100%, 90%, infinite, and 0.2, respectively, for the surgical biopsy cohort.

CONCLUSION

Obtaining multiple good quality tissue biopsies in a sterile environment will contribute to the diagnosis of a chronic PJI of the hip, with a higher diagnostic accuracy compared with ultrasound-guided thin needle biopsies and compared with synovial fluid culture alone.

Histopathology in Periprosthetic Joint Infection: When Will the Morphomolecular Diagnosis Be a Reality?

The presence of a polymorphonuclear neutrophil infiltrate in periprosthetic tissues has been shown to correlate closely with the diagnosis of septic implant failure. The histological criterion considered by the Musculoskeletal Infection Society to be diagnostic of periprosthetic joint infection is “greater than five neutrophils per high-power field in five high-power fields observed from histologic analysis of periprosthetic tissue at ×400 magnification.” Surgeons and pathologists should be aware of the qualifications introduced by different authors during the last years in the histological techniques, samples for histological study, cutoffs used for the diagnosis of infection, and types of patients studied. Recently, immunohistochemistry and histochemistry studies have appeared which suggest that the cutoff point of five polymorphonuclear neutrophils in five high-power fields is too high for the diagnosis of many periprosthetic joint infections. Therefore, morphomolecular techniques could help in the future to achieve a more reliable histological diagnosis of periprosthetic joint infection.

Contamination risk of synovial biopsy cultures in total hip arthroplasty: a prospective review of 100 cases

INTRODUCTION

Cultures of deep synovial biopsies remain an important tool in diagnosing periprosthetic joint infection, a devastating complication following total hip arthroplasty (THA). Recent reports of unexpected positive intraoperative cultures in aseptic revision arthroplasty, however, challenge the validity and interpretation of these cultures. The aim of this study was to evaluate the contamination risk of synovial biopsy cultures collected intraoperatively during primary THA of healthy subjects.

METHODS

Synovial biopsies for culture were collected during primary total hip arthroplasty procedures from 100 consecutive cases. The synovial biopsies were taken within the first 15 minutes after skin incision. Biopsy specimen were cultured on 4 different media for 8 or 15 days. Positive cultures were identified using Maldi-Tof spectrometry.

RESULTS

16 cultures yielded a bacterium, suggesting a false positive result of 16%. The mean time for the cultures to become positive was 6.29 days (standard deviation [SD] 3.90) with a maximum of 15 days. Proprionibacterium acnes and Staphylococcus epidermidis were most commonly cultured with 6 positive results for both bacteria.

CONCLUSIONS

Our study yielded a 16% false positive rate in cultures of synovial biopsy taken during primary total hip arthroplasty of healthy subjects, suggesting that contamination risk of these synovial biopsy cultures may be larger than assumed by clinicians.

Prosthetic joint infection development of an evidence-based diagnostic algorithm

BACKGROUND

Increasing rates of prosthetic joint infection (PJI) have presented challenges for general practitioners, orthopedic surgeons and the health care system in the recent years. The diagnosis of PJI is complex; multiple diagnostic tools are used in the attempt to correctly diagnose PJI. Evidence-based algorithms can help to identify PJI using standardized diagnostic steps.

METHODS

We reviewed relevant publications between 1990 and 2015 using a systematic literature search in MEDLINE and PUBMED. The selected search results were then classified into levels of evidence. The keywords were prosthetic joint infection, biofilm, diagnosis, sonication, antibiotic treatment, implant-associated infection, Staph. aureus, rifampicin, implant retention, pcr, maldi-tof, serology, synovial fluid, c-reactive protein level, total hip arthroplasty (THA), total knee arthroplasty (TKA) and combinations of these terms.

RESULTS

From an initial 768 publications, 156 publications were stringently reviewed. Publications with class I-III recommendations (EAST) were considered. We developed an algorithm for the diagnostic approach to display the complex diagnosis of PJI in a clear and logically structured process according to ISO 5807.

CONCLUSIONS

The evidence-based standardized algorithm combines modern clinical requirements and evidence-based treatment principles. The algorithm provides a detailed transparent standard operating procedure (SOP) for diagnosing PJI. Thus, consistently high, examiner-independent process quality is assured to meet the demands of modern quality management in PJI diagnosis.

Diagnostic accuracy of arthroscopic biopsy in periprosthetic infections of the hip

Background

Diagnosis of a low-grade periprosthetic joint infection (PJI) prior to revision surgery can be challenging, despite paramount importance for further treatment. Arthroscopic biopsy of synovial and periprosthetic tissue with subsequent microbiological and histological examination can be beneficial but its specific diagnostic value has not been clearly defined.

Methods

20 consecutive patients who underwent percutaneous synovial fluid aspiration as well as arthroscopic biopsy due to suspected PJI of the hip and subsequent one- or two-stage revision surgery at our institution between January 2012 and May 2015 were enrolled. Indication was based on the criteria (1) history of PJI and increased levels of erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), (2) suspicious cell count and differential but negative bacterial culture in synovial aspirate, (3) early loosening (<less than 2 years), or (4) persisting pain without loosening but history of a PJI. At least two criteria had to be fulfilled in order to perform an arthroscopic biopsy.

Results

Best overall diagnostic value was identified for arthroscopic biopsy and a combination of bacteriological and histological analysis with a sensitivity of 87.5%, specificity of 100% and accuracy of 95%. Bacteriological assessment of synovial aspirate revealed a sensitivity of 50.0%, specificity of 91.7%, and accuracy of 75%. ESR and CRP yielded a sensitivity of 75.0% for either hematologic test and specificities of 87.5 and 66.7%, respectively.

Conclusions

In conclusion, our data indicate that arthroscopic biopsy is superior to ESR and CRP as well as joint aspiration and their combinations. Concurrent microbiological and histological examination of the biopsy specimens allows for identification of the causative pathogen and its susceptibility pattern in order to preoperatively plan the surgical strategy as well as the antibiotic regimen. Moreover, intraarticular mechanical failure can be detected during hip arthroscopy emphasizing its diagnostic value. Level II diagnostic study.

[Not Available]

Zusammenfassung. Mit stetig steigender Häufigkeit endoprothetischer Eingriffe nimmt auch die Bedeutung der damit vergesellschafteten Revisionschirurgie zu. Die Gelenksprothesen-Infektion ist hierbei eine der schwerwiegendsten Komplikationen, die zur Erlangung eines bestmöglichen Behandlungsergebnisses eine differenzierte Diagnose- und Therapiestrategie erfordert. Anamnese, klinische Untersuchung, Laborkontrollen, Radiologie (konventionelle und spezialisierte), Gelenkspunktion sowie Mikrobiologie und Histologie liefern entscheidende Hinweise zur Diagnosestellung als unabdingbare Voraussetzung zur Erstellung und Einleitung des entsprechenden Therapiekonzeptes. Insbesondere die Abgrenzung zwischen aseptischen und septischen Prothesenlockerungen ist schwierig und erfordert ein differenziertes und interdisziplinäres Vorgehen. Die kurative Behandlungsstrategie ist abhängig von: Dauer der Symptome, Latenz seit Primärimplantation, Keimspektrum, Antibiogramm und Weichteilverhältnissen und umfasst prothesenerhaltende Strategien bei nicht gelockerter Prothese, reizlosen Weichteilen und Abwesenheit von Problemkeimen, bis hin zum kompletten ein- oder zweizeitigen Prothesenwechsel bei einer chronischen Infektion. In diesem Beitrag werden die aktuellen Management-Konzepte der Gelenksprothesen-Infektionen diskutiert.

The value of arthroscopic neosynovium biopsies to diagnose periprosthetic knee joint low-grade infection

INTRODUCTION

The diagnostic algorithm in cases of assumed low-grade infection after total knee arthroplasty is discussed controversial. The aim of this study was to evaluate the reliability of neosynovium biopsies via knee arthroscopies in predicting a periprosthetic knee joint infection (PJI).

METHODS

From 2010 to 2015, 56 consecutive patients received a diagnostic arthroscopy of the knee joint by reason of an assumed PJI. In 34 cases, a revision arthroplasty was performed after the diagnostic arthroscopy. The microbiologic and histologic results from neosynovium biopsies were compared to intraoperative findings of the consecutively performed revision arthroplasty.

RESULTS

The arthroscopic neosynovium biopsies had a sensitivity of 0.88 (0.47-1.0 95 % confidence interval), a specificity of 0.88 (0.7-0.98), a positive predictive value of 0.7 (0.35-0.93), and a negative predictive value of 0.96 (0.79-1.0). The accuracy was 0.88. We determined a higher sensitivity of neosynovium biopsies compared to C-reactive protein (p = 0.038) and white blood cell count (p < 0.001) in serum. The itemized evaluation of histologic results showed a significant higher sensitivity compared to microbiologic results (p = 0.045) and a higher accuracy.

CONCLUSIONS

The analysis of arthroscopic neosynovium biopsies can be helpful to verify or exclude a PJI in selected patients. Especially, histologic assessment showed a high accordance with final results. Level of evidence IV, retrospective study.

The "true" incidence of surgically treated deep prosthetic joint infection after 32,896 primary total hip arthroplasties: a prospective cohort study

BACKGROUND AND PURPOSE

It has been suggested that the risk of prosthetic joint infection (PJI) in patients with total hip arthroplasty (THA) may be underestimated if based only on arthroplasty registry data. We therefore wanted to estimate the "true" incidence of PJI in THA using several data sources.

PATIENTS AND METHODS

We searched the Danish Hip Arthroplasty Register (DHR) for primary THAs performed between 2005 and 2011. Using the DHR and the Danish National Register of Patients (NRP), we identified first revisions for any reason and those that were due to PJI. PJIs were also identified using an algorithm incorporating data from microbiological, prescription, and clinical biochemistry databases and clinical findings from the medical records. We calculated cumulative incidence with 95% confidence interval.

RESULTS

32,896 primary THAs were identified. Of these, 1,546 had first-time revisions reported to the DHR and/or the NRP. For the DHR only, the 1- and 5-year cumulative incidences of PJI were 0.51% (0.44-0.59) and 0.64% (0.51-0.79). For the NRP only, the 1- and 5-year cumulative incidences of PJI were 0.48% (0.41-0.56) and 0.57% (0.45-0.71). The corresponding 1- and 5-year cumulative incidences estimated with the algorithm were 0.86% (0.77-0.97) and 1.03% (0.87-1.22). The incidences of PJI based on the DHR and the NRP were consistently 40% lower than those estimated using the algorithm covering several data sources.

INTERPRETATION

Using several available data sources, the "true" incidence of PJI following primary THA was estimated to be approximately 40% higher than previously reported by national registries alone.

Preoperative aspiration culture for preoperative diagnosis of infection in total hip or knee arthroplasty

This meta-analysis evaluated preoperative aspiration culture for diagnosing prosthetic joint infection (PJI) in total hip arthroplasty (THA) and total knee arthroplasty (TKA). The pooled sensitivity and specificity were 0.72 (95% confidence interval, 0.65 to 0.78) and 0.95 (0.93 to 0.97), respectively. Subgroup analyses revealed nonsignificant worse diagnostic performance for THA than for TKA (sensitivity, 0.70 versus 0.78; specificity, 0.94 versus 0.96). Preoperative aspiration culture has moderate to high sensitivity and very high specificity for diagnosing PJI.

Swab cultures are not as effective as tissue cultures for diagnosis of periprosthetic joint infection

BACKGROUND

While it is accepted accurate identification of infecting organisms is crucial in guiding treatment of periprosthetic joint infection (PJI), there remains no consensus regarding the best method for obtaining cultures.

QUESTIONS/PURPOSES

We compared the yield of intraoperative tissue samples versus swab cultures in diagnosing PJI.

METHODS

Tissue and swab cultures (three each) were collected prospectively during a consecutive series of 156 aseptic and septic revision arthroplasties from October 2011 to April 2012. The tissues and swabs were taken from standardized regions of the joint. After excluding 39 reimplantation procedures, we included 117 cases (74 hip, 43 knee; 30 septic, 87 aseptic) for analysis. We used a modified version of the Musculoskeletal Infection Society criteria for defining PJI, requiring three of five rather than four of six criteria. Tissue and swab cultures from septic and aseptic cases were used to calculate their sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for identifying PJI.

RESULTS

Tissue cultures were positive in a higher percentage of septic cases than swab cultures: 28 of 30 (93%) versus 21 of 30 (70%). Tissue cultures were positive in two of 87 aseptic cases (2%), while swab cultures were positive in 10 of 87 (12%). The sensitivity, specificity, PPV, and NPV were 93%, 98%, 93%, and 98%, respectively, for tissue cultures and 70%, 89%, 68%, and 90%, respectively, for swab cultures.

CONCLUSIONS

Tissue cultures demonstrated higher sensitivity, specificity, PPV, and NPV for diagnosing PJI than swab cultures. Swab cultures had more false-negative and false-positive results than tissue cultures. Because swab cultures pose a higher risk of not identifying or incorrectly identifying infecting organisms in PJI, we believe their use in obtaining intraoperative culture specimens should be discouraged.

LEVEL OF EVIDENCE

Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

High diagnostic value of synovial biopsy in periprosthetic joint infection of the hip

BACKGROUND

The role of the synovial biopsy in the preoperative diagnosis of a periprosthetic joint infection (PJI) of the hip has not been clearly defined.

QUESTIONS/PURPOSES

We asked whether the value of a biopsy for a PJI is greater than that of aspiration and C-reactive protein (CRP).

METHODS

Before revision in 100 hip endoprostheses, we obtained CRP values, aspirated the joint, and obtained five synovial biopsy samples for bacteriologic analysis and five for histologic analysis. Microbiologic and histologic analyses of the periprosthetic tissue during revision surgery were used to verify the results of the preoperative diagnostic methods. The minimum followup was 24 months (median 32; range, 24-47 months).

RESULTS

Forty-five of the 100 prostheses were identified as infected. The biopsy, with a combination of the bacteriologic and histologic examinations, showed the greatest diagnostic value of all the diagnostic procedures and led to a sensitivity of 82% (95% CI, ± 11%), specificity of 98% (95% CI, ± 4%), positive predictive value of 97% (95% CI, ± 5%), negative predictive value of 87% (95% CI, ± 8.3%), and accuracy of 91%.

CONCLUSIONS

The biopsy technique has a greater value than aspiration and CRP in the diagnosis of PJI of the hip (Masri et al. J Arthroplasty 22:72-78, 2007). In patients with a negative aspirate, but increased CRP or clinical signs of infection, we regard biopsy to be preferable to just repeating the aspiration.

LEVEL OF EVIDENCE

Level II prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Leukocyte esterase reagent strips for the rapid diagnosis of periprosthetic joint infection

A total of 223 consecutive total hip or total knee arthroplasties were evaluated for periprosthetic joint infection (PJI) using leukocyte esterase reagent (LER) strips. Fifty-two LER strips were read as positive (23.3%), 106 were read as negative (47.5%), and 65 strips (29.2%) were unable to be read secondary to debris or blood in the aspiration. Using a synovial fluid white blood cell count of greater than 3000 white blood cell per microliter as an indicator of PJI, the sensitivity and specificity were 92.9% and 88.8%, respectively. When using positive cultures for diagnosis of PJI, sensitivity and specificity were 93.3% and 77.0% and 100% and 86.8% for the cases where a reoperation was performed and a combination of factors were used to define PJI. Leukocyte esterase reagent strips represent a rapid, inexpensive, and sensitive tool for the diagnosis of PJI. Their utility is limited, however, by blood or debris in the synovial fluid rendering them unreadable in one-third of cases.

Mark B. Coventry Award: synovial C-reactive protein: a prospective evaluation of a molecular marker for periprosthetic knee joint infection

BACKGROUND

C-reactive protein (CRP) serum assays are a standard element of the diagnostic workup for periprosthetic joint infection (PJI). However, because CRP is a marker for systemic inflammation, this test is not specific to PJI.

QUESTIONS/PURPOSES

Our purpose was to assess whether synovial fluid and serum assays alone could differentiate between infected and uninfected revision knee arthroplasties and to determine which of these methods had the greatest diagnostic accuracy.

METHODS

We collected synovial fluid specimens from 66 patients undergoing revision total knee arthroplasty. Patients were judged uninfected or infected by standardized criteria. Synovial CRP levels were measured using an individual CRP assay (15 samples; 10 infected, five uninfected) and a multiplex immunoassay platform (59 samples; 25 infected, 34 uninfected). Results from preoperative standard serum CRP assays conducted were also collected (55 samples; 25 infected, 30 uninfected). Sensitivity, specificity, and receiver operating characteristic curve analyses were performed for each assay with a diagnosis of infection based on previously established criteria.

RESULTS

Synovial CRP concentrations differed between infected and uninfected joints in the multiplex and serum analyses. The area under the curve was 0.84 for the individual assay, 0.91 for the multiplex assay, and 0.88 for the serum CRP assay. Sensitivity and specificity were 70.0% and 100.0% for the individual enzyme-linked immunosorbent assay, 84.0% and 97.1% for the multiplex assay, and 76.0% and 93.3% for the serum CRP assay.

CONCLUSIONS

An assay measuring CRP in synovial fluid may be more accurate in diagnosing PJI than the standard serum CRP assay. We believe such an assay holds promise as a new diagnostic marker for PJI.

Diagnosis of periprosthetic joint infections of the hip and knee

No preferred test for diagnosis of periprosthetic joint infection exists, and the algorithm for the workup of patients suspected of infection remains unclear. The work group evaluated the available literature to determine the role of each diagnostic modality and devise a practical algorithm that allows physicians to reach diagnosis of periprosthetic joint infection. Ten of the 15 recommendations have strong or moderate evidence in support. These include matters involving erythrocyte sedimentation rate and C-reactive protein level testing, knee and hip aspiration, and stopping the use of antibiotics prior to obtaining intra-articular cultures. The group recommends against the use of intraoperative Gram stain but does recommend the use of frozen sections of peri-implant tissues in reoperation patients in whom infection has not been established, as well as multiple cultures in reoperation patients being assessed for infection. The group recommends against initiating antibiotic treatment in patients with suspected infection until after joint cultures have been obtained, but recommends that prophylactic preoperative antibiotics not be withheld in patients at lower probability for infection.

Is there a role for tissue biopsy in the diagnosis of periprosthetic infection?

BACKGROUND

Successful treatment of an infected joint arthroplasty depends on correctly identifying the responsible pathogens. The value of a preoperative biopsy remains controversial.

QUESTIONS/PURPOSES

We (1) compared the sensitivity and specificity of both tests separately and in combination, and (2) asked whether the combination of tissue biopsy and aspiration would improve our diagnostic yield in the evaluation of periprosthetic joint infections.

PATIENTS AND METHODS

We prospectively followed 120 patients with suspected infection of a total joint arthroplasty: 64 with THAs and 56 with TKAs. All patients had aspiration with culture and biopsy.

RESULTS

The sensitivity was 83% for aspiration, 79% for biopsy, and 90% for the combination of both techniques. The specificity was 100% for aspiration and biopsy and the combination. The overall accuracy was 84%, 81%, and 90%, respectively.

CONCLUSIONS

Our data suggest tissue biopsy alone offers no clear advantage over joint aspiration. However, the combination of both techniques provides improved sensitivity and accuracy. We recommend the use of tissue biopsy as an adjunct to joint aspiration in the diagnosis of total joint infection.

LEVEL OF EVIDENCE

Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

[Histopathologic diagnosis of infectious loosening of joint prostheses]

To optimize the reliability of histopathological criteria for periprosthetic infection, 110 tissue specimens from joint prostheses were analyzed with quantification of the inflammatory cells and immunohistochemical typing of lymphocytes and plasma cells. As reported in the literature the density of granulocytic infiltration was the most sensitive marker of periprosthetic infection with an accuracy of 84%, a sensitivity of 91%, a specificity of 81%, a positive predictive value of 67%, and a negative predictive value of 95%, using the mostly favored limit value of 5 granulocytes per HPF. T lymphocytes were also found to a high degree in cases of aseptic loosening. In contrast, B lymphocytes were predominantly seen in cases with periprosthetic infection. For B lymphocytes an accuracy of 80% and a sensitivity of 79% were calculated and for plasma cells an accuracy of 75% and a sensitivity of 79%. Our data suggest that the quantification of granulocyte, B-cell, and plasma cell infiltrates is an important parameter for verifying the diagnosis of periprosthetic infection.

Structural allografts for bone stock reconstruction in two-stage revision for infected total hip arthroplasty: good outcome in 16 of 18 patients followed for 5-14 years

BACKGROUND

The use of massive bone allografts in cases of revision of failed total hip arthroplasties (THAs) due to infection is controversial.

PATIENTS AND METHODS

18 patients presented with infection at the site of a THA and were treated with a two-stage protocol. In the first stage, the prosthesis was removed together with all necrotic tissues and cement material if present. A custom-made mold of Palacos R cement containing 1 g of gentamicin was then inserted in 17 of the 18 patients. Systemic antibiotics were used during the interval period. In the second stage, the patients had either acetabular or femoral reconstruction using bulk allograft bone.

RESULTS

Mean follow-up was 9 (5-14) years. 1 patient presented with recurrent infection and underwent a Girdlestone resection arthroplasty as definitive treatment. Another patient had a mechanical failure of the acetabular component, which was revised 10 years after the second stage of the reconstruction. The mean Harris Hip Score improved from 34 points preoperatively to 71 points at the last review. By our definition, 16/18 of the patients had a successful outcome.

INTERPRETATION

Our results support the use of massive allografts in staged reconstructions of infected THAs complicated by considerable bone loss.