Utility of intraoperative frozen section histopathology in the diagnosis of periprosthetic joint infection: a systematic review and meta-analysis

Diagnostic accuracy of preoperative percutaneous synovial biopsy and aspirate compared with open biopsy for prosthetic shoulder infections

BACKGROUND

Shoulder arthroplasty revision is associated with a high prevalence of prosthetic infection, and diagnosis remains difficult. The primary aim of the study was to determine the diagnostic accuracy of percutaneous synovial biopsy (PSB) and joint aspiration compared with open culture results in detecting infection in revision shoulder arthroplasty. The second aim was to determine whether biopsy location within the shoulder was associated with culture status.

METHODS

This was a multicenter prospective cohort study involving 4 sites and 69 patients undergoing revision shoulder arthroplasty. The cohort was 57% female with a mean age of 64 years. Preoperative fluoroscopic-guided PSBs and aspirations were carried out by a musculoskeletal radiologist before revision shoulder arthroplasty. The original prostheses consisted of hemiarthroplasties, total shoulder arthroplasties (TSAs), resurfacing TSA, reverse shoulder arthroplasties (RSAs), and antibiotic spacers. Six synovial tissue biopsies from separate regions in the shoulder were obtained both preoperatively and intraoperatively. The shoulder joint was aspirated, and synovial fluid collected, if available. Infection was considered positive in the setting of 2 or more matching positive cultures. The PSB cultures were considered "true positive" if the PSB cultures matched the open biopsy cultures.

RESULTS

Nineteen percent had positive infection based on PSB, and 23% had confirmed culture-positive infections based on intraoperative biopsy. The diagnostic accuracy of PSB compared with open biopsy was as follows: sensitivity 0.37 (95% confidence interval [CI] 0.13-0.61), specificity 0.81 (95% CI 0.7-0.91), positive predictive value 0.37 (95% CI 0.13-0.61), negative predictive value 0.81 (95% CI 0.70-0.91), positive likelihood ratio 1.98, and negative likelihood ratio 0.77. Of the 71 patients from whom aspirates were collected, aspiration yielded synovial fluid in 33 patients. Preoperative aspiration detected no infections confirmed positive by open biopsy and correctly identified 81% of absent infections. The diagnostic accuracy of aspiration compared with open biopsy was as follows: sensitivity 0%, specificity 0.81 (95% CI 0.66-0.96), positive predictive value 0%, and negative predictive value 0.78 (95% CI 0.63-0.93). Biopsy location within the shoulder was not associated with infection status.

DISCUSSION

Preoperative aspiration detected none of the infections proven positive via open biopsy. Although PSB was superior to synovial fluid aspirate, poor likelihood ratios suggest that PSB is not useful as an isolated test in the preoperative workup of the potentially infected patient. Biopsy location was not associated with culture status suggesting that the capsule is uniformly infected, and the location of tissue biopsies does not appear to matter.

Updates in non-neoplastic orthopaedic pathology: what you don't know can hurt you!

Even though the average surgical pathologist reviews far more non-neoplastic orthopaedic pathology on a daily basis, most current research focuses on rare tumours and their even less frequent molecular events. Our experiences among consults and focused conferences strongly suggest that there remains a practice gap regarding knowledge and diagnosing specific non-neoplastic orthopaedic conditions. One of the most frequent intraoperative consultations performed in the USA, among both academic and private institutions, relates to revision arthroplasty and the determination of infection in periprosthetic joints. Pathologists play a critical role in this algorithm, helping determine intraoperatively whether patients require antibiotic spacers prior to reimplantation. Many pathology departments have abandoned the examination of arthroplasty specimens because they (and their surgeons) mistakenly believe there is little clinically relevant information to be gained by thorough pathological examination. However, recent literature has challenged this concept, emphasising the importance of distinguishing avascular necrosis (from osteoarthritis/degenerative joint disease with secondary osteonecrosis), subchondral insufficiency fracture, septic arthritis (from so-called 'sterile' osteomyelitis/pseudoabscesses), underlying crystalline diseases and incidental/occult neoplasia. Histological evaluation of historically insignificant orthopaedic specimens, such as tenosynovium from carpal tunnel syndrome/trigger finger, is now seen as valuable in early diagnosis of cardiac amyloidosis. Not infrequently, orthopaedic conditions like haemosiderotic synovitis, osteocartilaginous loose bodies or rheumatoid nodules, may histologically mimic bona fide neoplasms, notably diffuse tenosynovial giant cell tumour, synovial chondromatosis and epithelioid sarcoma, respectively. Here is a review of the more common non-neoplastic orthopaedic conditions, those likely to be examined by the practising surgical pathologist, with updates and guidelines for establishing clinically relevant diagnoses.

Imaging in Periprosthetic Joint Infection Diagnosis: A Comprehensive Review

Various imaging methods assist in diagnosing periprosthetic joint infection (PJI). These include radiological techniques such as radiography, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US); as well as advanced nuclear medicine techniques including bone scintigraphy (BS), anti-granulocyte antibody imaging (AGS), leukocyte scintigraphy (LS), and fluorodeoxyglucose positron emission tomography (FDG-PET and FDG-PET/CT). Each imaging technique and radiopharmaceutical has been extensively studied, with unique diagnostic accuracy, limitations, and benefits for PJI diagnosis. This review aims to detail and describe the most commonly used imaging techniques and radiopharmaceuticals for evaluating PJI, focusing particularly on knee and hip arthroplasties.

Difficulty of diagnostic accuracy of periprosthetic joint infection: a retrospective analysis of revision surgery of total hip arthroplasty and total knee arthroplasty in a tertiary hospital

BACKGROUND

Diagnostic accuracy of periprosthetic joint infection still remains controversial and an unsolved problem with respect to clinical signs and laboratory measures. Influencing factors of diagnosis like age, sex, abnormal physical findings and comorbidities are published with different results. The aim of our study was to find factors strengthening the diagnosis.

METHODS

We therefore retrospectively investigated all revision surgeries of total knee arthroplasty and total hip arthroplasty in the years 2019 and 2020 in a tertiary hospital with special regard to diagnostic accuracy of periprosthetic joint infection and switch in diagnosis to aseptic mechanical loosening or vice versa. All patients were divided into 4 non-hierarchical groups: suspected and discharge diagnosis periprosthetic joint infection (P1), suspected and discharge diagnosis mechanical loosening (P2), suspected diagnosis mechanical loosening and discharge diagnosis periprosthetic joint infection (P3), suspected diagnosis PJI and discharge diagnosis mechanical loosening (P4).

RESULTS

In the years 2019-2020, 106 patients underwent revision surgery of total knee arthoplasty and total hip arthroplasty. 33 patients showed periprosthetic joint infection (31.1%) according to Infectious Diseases Society (IDSA) criteria, 73 patients showed mechanical loosening (68.9%). Of the periprosthetic joint infection -patients, 15 were men (46%) and 18 were women (54%). The patients with mechanical loosening were 27 men (37%) and 46 women (63%). In group P1 (25 patients), 22 could be classified according to the histopathological classification Krenn and Morawietz grade 2 and grade 3, 2 patients to grade 4 and one patient could not be classified. In group P3 (8 patients) all could be classified according to the classification Krenn and Morawietz grade 2 and 3. Groups P1 - P4 were correlated with categorial basic data: All Groups P1 - P4 showed a statistical correlation towards American Society of Anesthesiologists (ASA) categorization 3-4 versus ASA 2 (p = 0.01). In the pairwise comparison in the exact Fisher´s exact test P1 and P2 showed a statistical correlation towards ASA categorization 3-4 versus ASA 2 (p = 0.01). Charlson Comorbidity Index (CCI) categories 5-7 versus 0,1-2 and 3-4 showed a statistical correlation towards groups P1-P4 (p = 0.007) and in the pairwise comparison in the exact Fisher´s exact test a discrimination of P1 and P2 (p = 0.001) and P1 and P3 (p = 0.007). The preoperative corticoid therapy showed a statistical correlation to groups P1-P4 (p = 0.05) and in the pairwise comparison in the exact Fisher test a discrimination of P1 and P4 (p = 0.02).

CONCLUSION

We therefore conclude that diagnosis of periprosthetic joint infection still remains difficult. Switches in diagnosis during hospital stay from periprosthetic joint infection to aseptic mechanical loosening and vice versa are not unusual and the role of different diagnostic tools needs further investigation. Patients categorized according to ASA and CCI as severely ill might be more likely to be diagnosed correctly with periprosthetic joint infection.

Practical Guidance for Clinical Microbiology Laboratories: Microbiologic diagnosis of implant-associated infections

SUMMARYImplant-associated infections (IAIs) pose serious threats to patients and can be associated with significant morbidity and mortality. These infections may be difficult to diagnose due, in part, to biofilm formation on device surfaces, and because even when microbes are found, their clinical significance may be unclear. Despite recent advances in laboratory testing, IAIs remain a diagnostic challenge. From a therapeutic standpoint, many IAIs currently require device removal and prolonged courses of antimicrobial therapy to effect a cure. Therefore, making an accurate diagnosis, defining both the presence of infection and the involved microorganisms, is paramount. The sensitivity of standard microbial culture for IAI diagnosis varies depending on the type of IAI, the specimen analyzed, and the culture technique(s) used. Although IAI-specific culture-based diagnostics have been described, the challenge of culture-negative IAIs remains. Given this, molecular assays, including both nucleic acid amplification tests and next-generation sequencing-based assays, have been used. In this review, an overview of these challenging infections is presented, as well as an approach to their diagnosis from a microbiologic perspective.

Two-stage revision for periprosthetic joint infection after hip and knee arthroplasty

Aims

Histology is widely used for diagnosis of persistent infection during reimplantation in two-stage revision hip and knee arthroplasty, although data on its utility remain scarce. Therefore, this study aims to assess the predictive value of permanent sections at reimplantation in relation to reinfection risk, and to compare results of permanent and frozen sections.

Methods

We retrospectively collected data from 226 patients (90 hips, 136 knees) with periprosthetic joint infection who underwent two-stage revision between August 2011 and September 2021, with a minimum follow-up of one year. Histology was assessed via the SLIM classification. First, we analyzed whether patients with positive permanent sections at reimplantation had higher reinfection rates than patients with negative histology. Further, we compared permanent and frozen section results, and assessed the influence of anatomical regions (knee versus hip), low- versus high-grade infections, as well as first revision versus multiple prior revisions on the histological result at reimplantation. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), chi-squared tests, and Kaplan-Meier estimates were calculated.

Results

Overall, the reinfection rate was 18%. A total of 14 out of 82 patients (17%) with positive permanent sections at reimplantation experienced reinfection, compared to 26 of 144 patients (18%) with negative results (p = 0.996). Neither permanent sections nor fresh frozen sections were significantly associated with reinfection, with a sensitivity of 0.35, specificity of 0.63, PPV of 0.17, NPV of 0.81, and accuracy of 58%. Histology was not significantly associated with reinfection or survival time for any of the analyzed sub-groups. Permanent and frozen section results were in agreement for 91% of cases.

Conclusion

Permanent and fresh frozen sections at reimplantation in two-stage revision do not serve as a reliable predictor for reinfection.

Utility of histopathological examination in aseptic revision total hip arthroplasty: a preliminary analysis

INTRODUCTION

The utility of a routine histopathological examination in aseptic revision total hip arthroplasty (THA) has not been well explored. We aim to describe the approach and present the results of histopathological examination, focusing on its clinical usefulness in the setting of aseptic revision THA.

METHOD

We retrospectively reviewed 285 performed aseptic revision THA with available histopathological reports between 2015 and 2017 at a single institution. We described histopathological requests by the surgical team. Preoperative diagnoses, intraoperative findings, as well as histopathology and culture results were analysed.

RESULTS

13 painful THAs (4.5%) had preoperatively unknown diagnoses. In 10 of them, potential causes of pain were intraoperatively identified. Histopathology confirmed these findings in 8 THAs. 19 THAs (6.7%) revealed unexpected positive cultures (UPC). Histopathology was negative for infection in 18 of them. Among 16 consultants, 3 surgeons requested histopathology in 47% of the cases (130/285), usually to exclude infection (101/285; 35%). Documentation for tissue sample location was lacking in 51% (145/285), and for question asked by the surgeon in 47% (135/285).

CONCLUSIONS

Histopathology is deemed a useful confirmatory tool in the context of ruling out infection in UPCs, and in documenting intraoperative findings in painful THAs with unknown preoperative diagnoses. Importantly, the approach to requesting histopathology should be optimised. Further large-scale studies, including cost analyses, are warranted to explore the usefulness of histopathology in routine utility.

The Challenge of Periprosthetic Joint Infection Diagnosis: From Current Methods to Emerging Biomarkers

Due to the increase in the life span and mobility at older ages, the number of implanted prosthetic joints is constantly increasing. However, the number of periprosthetic joint infections (PJIs), one of the most severe complications after total joint arthroplasty, also shows an increasing trend. PJI has an incidence of 1-2% in the case of primary arthroplasties and up to 4% in the case of revision operations. The development of efficient protocols for managing periprosthetic infections can lead to the establishment of preventive measures and effective diagnostic methods based on the results obtained after the laboratory tests. In this review, we will briefly present the current methods used in PJI diagnosis and the current and emerging synovial biomarkers used for the prognosis, prophylaxis, and early diagnosis of periprosthetic infections. We will discuss treatment failure that may result from patient factors, microbiological factors, or factors related to errors during diagnosis.

Validation of the diagnostic criteria of the consensus definition of fracture-related infection

BACKGROUND

The recently developed fracture-related infection (FRI) consensus definition, which is based on specific diagnostic criteria, has not been fully validated in clinical studies. We aimed to determine the diagnostic performance of the criteria of the FRI consensus definition and evaluated the effect of the combination of certain suggestive and confirmatory criteria on the diagnostic performance.

METHODS

A multicenter, multi-national, retrospective cohort study was performed. Patients were subdivided into an FRI or a control group, according to the treatment they received and the recommendations from a multidisciplinary team ('intention to treat'). Exclusion criteria were patients with an FRI diagnosed outside the study period, patients younger than 18 years of age, patients with pathological fractures or patients with fractures of the skull, cervical, thoracic and lumbar spine. Minimum follow up for all patients was 18 months.

RESULTS

Overall, 637 patients underwent revision surgery for suspicion of FRI. Of these, 480 patients were diagnosed with FRI, treated accordingly, and included in the FRI group. The other 157 patients were included in the control group. The presence of at least one confirmatory sign was associated with a sensitivity of 97.5%, a specificity of 100% and a high discriminatory value (AUROC 0.99, p < 0.001). The presence of a clinical confirmatory criterion or, if not present, at least one positive culture was associated with the highest diagnostic performance (sensitivity: 98.6%, specificity: 100%, AUROC: 0.99 (p < 0.001)). In the subgroup of patients without clinical confirmatory signs at presentation, specificities of at least 95% were found for the clinical suggestive signs of fever, wound drainage, local warmth and redness.

CONCLUSIONS

The presence of at least one confirmatory criterion identifies the vast majority of patients with an FRI and was associated with an excellent diagnostic discriminatory value. Therefore, our study validates the confirmatory criteria of the FRI consensus definition. Infection is highly likely in case of the presence of a single positive culture with a virulent pathogen. When certain clinical suggestive signs (e.g., wound drainage) are observed (individually or in combination and even without a confirmatory criterion), it is more likely than not, that an infection is present.

Intraoperative frozen section histopathology for the diagnosis of periprosthetic joint infection in hip revision surgery: the influence of recent dislocation and/or periprosthetic fracture

AIMS

To evaluate the accuracy of intraoperative frozen section histopathology for diagnosing periprosthetic joint infection (PJI) during hip revision surgery, both for patients with and without recent trauma to the hip.

PATIENTS AND METHODS

The study included all revision total hip replacement procedures where intraoperative frozen section histopathology had been used for the evaluation of infection in a single institution between 2008 and 2015. Musculoskeletal Infection Society criteria were used to define infection. 210 hips were included for evaluation. Prior to revision surgery, 36 hips had a dislocation or a periprosthetic fracture (group A), and 174 did not (group B).

RESULTS

The prevalence of infection was 14.3% (5.6% in group A and 16.1% in group B). Using Feldman criteria, the sensitivity of histopathology was 50.0%, specificity 47.1%, positive predictive value 5.3% and negative predictive value 94.1% in group A. The sensitivity of frozen section histopathology was 75.0%, specificity 96.5%, positive predictive value 85% and negative predictive value 95.3% in group B.

CONCLUSIONS

Intraoperative frozen section histopathology is reliable for the diagnosis of PJI if no dislocation or periprosthetic fracture has occurred prior to hip revision surgery.

Diagnosis and management of infected arthroplasty

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

Early definitive internal fixation for infected nonunion of the lower limb

Background

The management of an infected nonunion of long bones is difficult and challenging. A staged procedure comprising radical debridement followed by definitive internal fixation was favored. However, no standard treatment has been established to determine the appropriate waiting period between initial debridement and definitive internal fixation. We propose a management method that incorporates early definitive internal fixation in infected nonunion of the lower limb.

Methods

Thirty-four patients (28 men and 6 women; mean age 46.09 years; range 25–74 years) with infected nonunion of the tibia or femur were included. Initial infected bone resection and radical debridement were performed in each patient in accordance with the preoperative plans. Definitive surgery was performed 2–3 weeks after the resection (4 weeks after flap surgery was required), and a third surgery was performed to fill the bone defect through bone grafting or transport (three-stage surgery). In cases of unplanned additional surgery, the reason for the requirement was analyzed, and radiological and functional results were investigated in accordance with the Association for the Study and Application of the Method of Ilizarov criteria.

Results

Bone union was achieved in all patients, and treatment was conducted as planned preoperatively in 28 patients (28/34, 82.35%). The mean interval between primary debridement and secondary definitive fixation was 2.76 weeks (range 2–4 weeks). Six unplanned additional surgeries were performed, and the infection relapsed in two cases. The radiological and functional outcomes were good or better in 32 and 31 patients, respectively.

Conclusions

Early definitive surgery can be performed to treat infected nonunion by thorough planning and implementation of radical resection, active response to infection, restoration of defective bones, and soft tissue healing through a systemic approach.

Pathological analysis of periprosthetic soft tissue and modes of failure in revision total joint arthroplasty patients

Objectives

Implant failure leading to revision total joint arthroplasty can occur through a variety of different mechanisms which are typically associated with a soft tissue response adjacent to the implant that provide insight into the underlying etiology of implant failure. The objective of this study was to elucidate mechanisms of implant failure as they relate to histological classification and findings of adjacent periprosthetic tissue.

Methods

Histological analysis of soft tissue adjacent to the implant was performed in 99 patients with an average age of 64 years old and grouped into four categories based on the study conducted by Morawietz et al.:Type I (N = 47)Wear particle induced typeType II (N = 7)Infectious typeType III (N = 19)Combined type I and IIType IV (N = 26)Indeterminant typeModes of failure were categorized into five groupings based on the study conducted by Callies et al.: Instability (N = 35), Aseptic Loosening (N = 24), Hardware and/or Mechanical Failure (N = 15), Septic (N = 13), and Other failures (N = 12). We calculated odds ratios and conducted regression analysis to assess the relationship between modes of failure and histological findings as well as modes of failure and comorbidities.

Results

Hardware/mechanical failure was independently correlated with histological findings of anucleate protein debris, histiocytes, Staphylococcus epidermidis, and synovitis. Furthermore, hardware/mechanical failure was independently correlated with osteosarcoma as a co-morbidity. Septic failure was associated with histological findings of Enterococcus, granulation tissue, and tissue necrosis as well as comorbidities of Crohn's disease, deep venous thrombosis, lung disease, and rheumatoid arthritis. Infection was 5.8 times more likely to be associated with Type II histology. Aseptic loosening was associated with histologic findings of synovitis.

Conclusion

Our findings support the existing literature on periprosthetic tissue analysis in revision total joint arthroplasty which may improve surgeon understanding of the patholophysiological mechanisms that contribute to implant failure and revision surgery.

Diagnostic accuracy of neutrophil counts in histopathological tissue analysis in periprosthetic joint infection using the ICM, IDSA, and EBJIS criteria

Aims

Histology is an established tool in diagnosing periprosthetic joint infections (PJIs). Different thresholds, using various infection definitions and histopathological criteria, have been described. This study determined the performance of different thresholds of polymorphonuclear neutrophils (≥ 5 PMN/HPF, ≥ 10 PMN/HPF, ≥ 23 PMN/10 HPF) , when using the European Bone and Joint Infection Society (EBJIS), Infectious Diseases Society of America (IDSA), and the International Consensus Meeting (ICM) 2018 criteria for PJI.

Methods

A total of 119 patients undergoing revision total hip (rTHA) or knee arthroplasty (rTKA) were included. Permanent histology sections of periprosthetic tissue were evaluated under high power (400× magnification) and neutrophils were counted per HPF. The mean neutrophil count in ten HPFs was calculated (PMN/HPF). Based on receiver operating characteristic (ROC) curve analysis and the z-test, thresholds were compared.

Results

Using the EBJIS criteria, a cut-off of ≥ five PMN/HPF showed a sensitivity of 93% (95% confidence interval (CI) 81 to 98) and specificity of 84% (95% CI 74 to 91). The optimal threshold when applying the IDSA and ICM criteria was ≥ ten PMN/HPF with sensitivities of 94% (95% CI 79 to 99) and 90% (95% CI 76 to 97), and specificities of 86% (95% CI 77 to 92) and 92% (95% CI 84 to 97), respectively. In rTKA, a better performance of histopathological analysis was observed in comparison with rTHA when using the IDSA criteria (p < 0.001).

Conclusion

With high accuracy, histopathological analysis can be supported as a confirmatory criterion in diagnosing periprosthetic joint infections. A threshold of ≥ five PMN/HPF can be recommended to distinguish between septic and aseptic loosening, with an increased possibility of detecting more infections caused by low-virulence organisms. However, neutrophil counts between one and five should be considered suggestive of infection and interpreted carefully in conjunction with other diagnostic test methods.

Cite this article: Bone Joint Res 2021;10(8):536–547.

Diagnostic value of the CD 15 focus score in two-stage revision arthroplasty of periprosthetic joint infections : High specificity in diagnosing infect eradication

INTRODUCTION

The purpose of this study is to use the CD15 focus score (FS) to determine the sensitivity and specificity of bacterial infection persistence in spacer-based two-stage revision arthroplasty.

METHODS

The analysis comprises 112 cases that were subjected to revision due to the presence of infection upon replacement of a joint endoprosthesis. The histopathological data were collected in accordance with the synovial-like interface membrane (SLIM) classification and the CD15-FS and correlated with the microbiological data (MD). The quantifying evaluation of the CD15-FS was performed without knowledge regarding the microbiological data (MD). Correlation with the MD was performed after a 14-day cultivation period.

RESULTS

With a single evaluation (1 focus, field area: 1.2 mm2) with a score value of 42, the CD15-FS showed a sensitivity for the eradication of infections of 0.64 and a specificity of 0.79 (PPV = 0.5; NPV = 0.87). With tenfold evaluation (10 foci, field area: 12 mm2) with a score value of 220, the sensitivity for the eradication was 0.68, the specificity 0.91 (PPV = 0.7; NPV = 0.89). No statistically significant correlation between the score values and the different infectious species could be detected. Based on the MD in 112 cases the rate of infection eradication was 75%. Polymethylmethacrylate-particles (PMMA) were detected in the perispacertissue in 64 cases (58%). No significant correlation could be established between microbiological pathogen detection and the presence of PMMA.

CONCLUSION

In all cases (n = 112), periimplant synovial tissue (SLIM) with variable fibroblastic cellularity, capillary proliferation, leukocytic infiltration, fibrin deposition, new formation of woven bone and detection of PMMA particles was observed. These cases were classified as type IX perispacer synovialis/SLIM: type IX‑A with histopathological infection eradication and type IX‑B with histopathological infection persistence.

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.

[Histological diagnostics in joint pathology due to increasing regenerative therapeutic strategies - special consideration for cartilage damage]

Orthopedic and trauma surgery are currently confronted with significant changes in their interventional and therapeutic strategies, especially in knee surgery. Minimally invasive and reconstructive techniques lead not only to modifications of the repertoire of interventional methods but also of the indications and questions for histopathological diagnostics. The classical problems in knee surgery remain important issues, which are traumatic, degenerative, and infectious lesions. In addition, questions regarding regeneration and integration of cell-material constructs will become more and more important in the future. Furthermore, questions regarding the regenerative potential of an implantation site for such constructs and the morphological quality of harvested tissue for the in vitro cell expansion of autologous cells are becoming increasingly important. The autologous chondrocyte transplantation is a good example of the relevance of the histopathological re-evaluation of the regenerated tissue for a better understanding of the pathophysiology of reconstructive therapies. It becomes clear that for specific aims based on reconstructive therapies, new scoring systems should be established for the histopathological routine diagnostic service. Furthermore, there is need for the definition of further histopathological criteria, which will help to optimize the differential application of reconstructive strategies via tissue engineering. The present report gives a short overview of the modifying requirements on the histopathological diagnostics in specimens from knee-surgery but does not claim to be exhaustive.

Diagnosing Osteomyelitis: A Histology Guide for Pathologists

Histopathologic examination of bone specimens coupled with bone culture is considered the gold standard for the diagnosis of osteomyelitis (OM). Despite this, studies have demonstrated interpathologist agreement in the diagnosis of OM as low as 30%, largely stemming from a lack of specific definitions and diagnostic criteria. Review of the literature has provided insight into the lifecycle of OM, illustrating the histologic progression of OM phases from acute to chronic, and provides support for defining subcategories of OM. Using an algorithmic histopathologic tool consisting of 15 criteria, each with an associated score, we defined 5 categories of OM: (1) acute OM, (2) acute and chronic OM, (3) chronic OM, (4) chronic active OM, and (5) chronic inactive OM. We reviewed 462 microscopic slides from 263 patients with suspected OM, and for each slide, we determined an algorithm-derived diagnosis, which was then used to calculate a total histopathologic load score (Jupiter score). Algorithm-derived diagnoses recapitulated original clinical diagnoses and diagnosed cases as OM that had not been originally diagnoses. These novel cases were more likely to have subsequent clinical complications. Finally, pathologic load scores were assessed for association with the category of OM.

Evolution of Diagnostic Definitions for Periprosthetic Joint Infection in Total Hip and Knee Arthroplasty

Various definitions and biomarkers have been developed in an unsuccessful attempt to obtain a "gold standard" for periprosthetic joint infection (PJI) diagnosis. The development of the 2011 Musculoskeletal Infection Society criteria facilitated further research and advances by allowing the use of a consistent PJI definition across studies. The newly proposed 2018 criteria do not rely at all on expert opinions/consensus. In this review, we describe the most relevant definitions developed throughout recent time, their rationale, characteristics, and supportive evidence for their clinical implementation. In the opinion of the authors, the orthopedic community should consider a probability and likelihood paradigm to create a PJI diagnostic definition. Probably not a single definition might be suited for all situations; the inclusion of serological findings could be the next step moving forward.

The host response to bacterial bone infection involves a local upregulation of several acute phase proteins

Bone infections often become chronic and can be difficult to diagnose. In the present study, the osseous gene expression of several acute phase proteins (APPs) during osteomyelitis was investigated in a porcine model of implant associated osteomyelitis (IAO) (sampled 5, 10 and 15 days after infection) and in slaughter pigs with spontaneous hematogenous osteomyelitis, and compared to gene expression in liver tissue. Furthermore, immunohistochemical (IHC) staining of the APP complement component C3 (C3) was performed on the porcine osteomyelitis lesions together with material from human patients with chronic osteomyelitis. In the porcine bone samples a local upregulation of the expression of several APP genes, including serum amyloid A (SAA) and C3, was observed during infection. In the liver, only C-reactive protein (CRP) and Inter-Alpha-Trypsin Inhibitor Heavy Chain 4 were significantly upregulated. Serum concentrations of CRP, SAA and haptoglobin were only upregulated at day 5 in infected animals of the IAO model. This indicates a limited systemic response to osteomyelitis. Similar numbers of positive IHC stained C3 leukocytes were found in human and porcine bone samples with chronic osteomyelitis, indicating a high transcriptional value of porcine models of osteomyelitis. The local upregulation of APPs could potentially be used for diagnosing osteomyelitis.

Reliability of intra-operative frozen section study in revision of infected hip arthroplasty

INTRODUCTION

Frozen sections are extensively used to help in the diagnosis of periprosthetic joint infection during revision hip arthroplasty, though there are insufficient data in relation to its usefulness.

METHODS

Twenty-one patients with infected hip arthroplasties were operated in the form of one or two-staged revision hip arthroplasties. A frozen section was obtained intra-operatively and > 5 PMN's/ HPF was considered as a positive indicator of infection. If the frozen section was reported negative (≤5 PMN's/HPF), the revision prosthesis was implanted after a thorough debridement and a wash. If the frozen section was reported as positive, post the debridement; a non-articulating antibiotic-loaded cement spacer was implanted for 8 weeks, supplemented with 3 weeks of intravenous antibiotics and 3 weeks of oral antibiotics. This was followed by an antibiotic-free interval of 2 weeks. The patient was taken up for a revision surgery once the frozen section study was negative (≤5 PMN's/HPF). The patients were followed up for a minimum of 1 year to a maximum of 2 years after the revision for any evidence of infection (assessed clinically, serologically, and radiologically).

RESULTS

Frozen section analysis of PMNs per high power field had a 100% specificity in our patients in detecting periprosthetic joint infection.

CONCLUSION

Frozen section study is a safe, rapid, cheap and reliable intra-operative modality to diagnose periprosthetic joint infection.

Acute Funisitis Correlates With the Risk of Early-Onset Sepsis in Term Newborns Assessed Using the Kaiser Sepsis Calculator

BACKGROUND

The risk of neonatal early-onset sepsis (EOS) is traditionally assessed on maternal signs of clinical chorioamnionitis. Recently, an online EOS risk calculator was developed by Kaiser Permanente using maternal and neonatal clinical parameters. We were interested in whether an increased Kaiser sepsis risk score correlates with histologic acute chorioamnionitis or acute funisitis.

DESIGN

Included in this retrospective review are 119 chorioamnionitis-exposed term neonates from January 1, 2015 and December 31, 2016. Clinical charts from mother-baby pairs were reviewed. An EOS risk score was obtained using the online Kaiser Sepsis Calculator. The presence and severity of acute chorioamnionitis and acute funisitis were recorded. A SPSS software was used for statistical analysis (IBM, New Jersey, USA).

RESULTS

The Kaiser Sepsis Calculator could identify 97 of 119 (81.5%) neonates without increased risk for sepsis. Histologic acute chorioamnionitis was present in 100 of 119 cases (84%), in which 44 cases (44%) show severe acute chorioamnionitis. Acute funisitis was recognized in 87 of 119 (73.1%) cases, all of which had concurrent acute chorioamnionitis. Severe funisitis was seen in 38 of the 87 cases (43.7%). The Kaiser Sepsis risk score correlates with the presence and severity of acute funisitis (P = .037 and P = .044, respectively) but not with the presence or the severity of acute chorioamnionitis (P = .105 and P = .672, respectively).

CONCLUSION

Our study provides histological evidence to support that the Kaiser Sepsis Calculator may help to effectively reduce unwarranted blood culture, antibiotics exposure, and neonatal intensive care unit admission in term neonates.

Is it safe to do a single-stage implant exit and primary hip replacement? clinical and microbiological profiling

BACKGROUND

A single-stage implant revision for failed fixation of proximal femoral fractures is performed only when there is no evidence of infection. Else, a two-staged revision is preferred - where the definitive revision surgery is done a few months after the implant exit. This study aims to audit the safety and incidence of culture positivity in single-stage revisions.

MATERIALS AND METHODS

Forty one of 284 patients that presented over the last 12 years for implant exchange of the hip, had a single stage revision surgery for failed fixation of a fracture of the hip, as there was no obvious evidence of infection at the time of implant exit.

RESULTS

Micro-organisms were grown in 51% of the 41 hips. 76% were gram positive, of which 63% were Coagulase negative staphylococci (CoNS). 50% of CoNS and 75% of S. aureus were resistant to oxacillin, but susceptible to Vancomycin. Of the gram negative organisms, 2 (Enterobacter sp) were resistant to carbapenam, while others were susceptible. Preoperative ESR and CRP, individually, had low specificity - 50% for ESR >30mm at 1 hour and 62% for CRP>10. The combined use of ESR > 30mm and CRP>10 increased the specificity to 90%. 12% of the patients had immediate postoperative complications that required a wash out in theatre. The long term clinical follow up of these patients is limited.

CONCLUSION

This study suggests that implant exit and simultaneous arthroplasty for failed fracture fixation should be done with caution due to the high possibility of infection. It may be prudent to opt for a 2 stage revision.

Diagnosis and Management of Fungal Periprosthetic Joint Infections

Fungal periprosthetic joint infection (PJI) is a devastating complication because it can be difficult to diagnose, manage, and eradicate. Fungal PJI treatment requires a systematic approach. Increased awareness is essential when patients with painful arthroplasties present with immunosuppression, significant comorbidities, multiple surgeries, and history of drug use. Every suspected fungal PJI should be promptly diagnosed using readily available serum and synovial fluid markers. Surgical management involves débridement, antibiotics, and implant retention, one-stage exchange arthroplasty, prosthetic articulating spacers, and two-stage exchange arthroplasty. Because mycotic infections develop robust biofilms, the utility of débridement, antibiotics, and implant retention and one-stage revisions seem limited. A thorough irrigation and débridement is essential to decrease infection burden. Adjunctive local and systemic antifungal therapy is critical, although the agent choice and duration should be tailored appropriately. Future high-quality studies are needed to develop standardized guidelines for the management of fungal PJI.

Synovial fluid α-defensin in the diagnosis of periprosthetic joint infection: the lateral flow test is an effective intraoperative detection method

Background

Synovial fluid α-defensin is a valuable biomarker for periprosthetic joint infection (PJI). Its diagnostic value for PJI has been widely evaluated recently, but results are inconsistent, especially for different test methods. The objective of this study was to evaluate the diagnostic value of laboratory-based immunoassay and lateral flow testing for the detection of α-defensin against hip and knee PJI.

Methods

We systematically searched MEDLINE and EMBASE for articles on the diagnostic accuracy of α-defensin for PJI published up to September 2018. The pooled sensitivity, specificity, area under the curve (AUC), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were calculated for the evaluation of the diagnostic value of α-defensin for PJI.

Results

Nineteen studies were included. Eleven evaluated laboratory-based immunoassay, and 10 evaluated the lateral flow test results. The pooled sensitivity, specificity, AUC, PLR, NLR, and DOR of laboratory-based immunoassays were 0.96 (95% confidence interval [CI] 0.90–0.98), 0.97 (95% CI 0.95–0.99), 0.99 (95% CI 0.98–1.00), 35.0 (95% CI 18.5–66.2), 0.04 (95% CI 0.02–0.11), and 811 (95% CI 220–2990), respectively. The pooled sensitivity, specificity, AUC, PLR, NLR, and DOR of the lateral flow test were 0.86 (95% CI 0.81–0.91), 0.96 (95% CI 0.93–0.98), 0.95 (95% CI 0.93–0.97), 21.2 (95% CI 11.7–38.5), 0.14 (95% CI 0.10–0.21), and 148 (95% CI 64–343), respectively.

Conclusions

Laboratory-based immunoassay of α-defensin is highly accurate for the diagnosis of hip and knee PJI. The lateral flow test is less sensitive but still a useful intraoperative detection tool for PJI.

Periprosthetic joint infection: current concepts and outlook

Periprosthetic joint infection (PJI) is a serious complication occurring in 1% to 2% of primary arthroplasties, which is associated with high morbidity and need for complex interdisciplinary treatment strategies.

The challenge in the management of PJI is the persistence of micro-organisms on the implant surface in the form of biofilm. Understanding this ability, the phases of biofilm formation, antimicrobial susceptibility and the limitations of host local immune response allows an individual choice of the most suitable treatment.

By using diagnostic methods for biofilm detection such as sonication, the sensitivity for diagnosing PJI is increasing, especially in chronic infections caused by low-virulence pathogens.

The use of biofilm-active antibiotics enables eradication of micro-organisms in the presence of a foreign body. The total duration of antibiotic treatment following revision surgery should not exceed 12 weeks.

Cite this article: EFORT Open Rev 2019;4:482-494. DOI: 10.1302/2058-5241.4.180092

What Strategies Can Be Implemented to Help Isolate the Causative Organism in Patients With Infection of the Foot and Ankle?

RECOMMENDATION

Transfer of synovial aspirate in blood culture bottles, obtaining deep biopsy of tissues and bone, obtaining multiple samples, increasing incubation period of cultures, and the use of molecular techniques for culture negative cases are some of the strategies that can help improve the ability to isolate the causative organism(s) in infections of foot and ankle.

LEVEL OF EVIDENCE

Moderate.

DELEGATE VOTE

Agree: 100%, Disagree: 0%, Abstain: 0% (Unanimous, Strongest Consensus).

The World Association against Infection in Orthopaedics and Trauma (WAIOT) procedures for Microbiological Sampling and Processing for Periprosthetic Joint Infections (PJIs) and other Implant-Related Infections

While implant-related infections continue to play a relevant role in failure of implantable biomaterials in orthopaedic and trauma there is a lack of standardised microbiological procedures to identify the pathogen(s). The microbiological diagnosis of implant-related infections is challenging due to the following factors: the presence of bacterial biofilm(s), often associated with slow-growing microorganisms, low bacterial loads, previous antibiotic treatments and, possible intra-operative contamination. Therefore, diagnosis requires a specific set of procedures. Based on the Guidelines of the Italian Association of the Clinical Microbiologists (AMCLI), the World Association against Infection in Orthopaedics and Trauma has drafted the present document. This document includes guidance on the basic principles for sampling and processing for implant-related infections based on the most relevant literature. These procedures outline the main microbiological approaches, including sampling and processing methodologies for diagnostic assessment and confirmation of implant-related infections. Biofilm dislodgement techniques, incubation time and the role of molecular approaches are addressed in specific sections. The aim of this paper is to ensure a standardised approach to the main microbiological methods for implant-related infections, as well as to promote multidisciplinary collaboration between clinicians and microbiologists.

Can leucocyte esterase replace frozen sections in the intraoperative diagnosis of prosthetic hip infection?

AIMS

Leucocyte esterase (LE) has been shown to be an accurate marker of prosthetic joint infection (PJI), and has been proposed as an alternative to frozen section (FS) histology for intraoperative diagnosis. In this study, the intraoperative assessment of LE was compared with FS histology for the diagnosis of prosthetic hip infection.

PATIENTS AND METHODS

A total of 119 patients undergoing revision total hip arthroplasty (THA) between June 2015 and December 2017 were included in the study. There were 56 men and 63 women with a mean age of 66.2 years (27 to 88). Synovial fluid was collected before arthrotomy for the assessment of LE using enzymatic colourimetric strips. Between five and six samples were stained with haematoxylin and eosin for FS histology, and considered suggestive of infection when at least five polymorphonuclear leucocytes were found in five high-power fields.

RESULTS

The sensitivity and specificity of the LE assay were 100% and 93.8%, respectively; the positive (PPV) and the negative (NPV) predictive values were 79.3% and 100%, respectively. The mean time between the collection of the sample and the result being known was 20.1 minutes (sd 4.4). The sensitivity and specificity of FS histology were 78.3% and 96.9%, respectively; the PPV and the NPV were 85.7% and 94.9%, respectively. The mean time between the collection of the sample and the result being known was 27.2 minutes (sd 6.9).

CONCLUSION

The sensitivity of LE assay was higher, with similar specificity and diagnostic accuracy, compared with FS histology. The faster turnaround time, its ease of use, and low costs make LE assay a valuable alternative to FS histology. We now use it routinely for the intraoperative diagnosis of PJI. Cite this article: Bone Joint J 2019;101-B:372-377.

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.

The role of alpha defensin in prosthetic joint infection (PJI) diagnosis: a literature review

Prosthetic joint infection (PJI) management is not standardized worldwide and the outcome is frequently unsatisfactory.More and more arthroplasties are now being performed. An increasing number of highly virulent and antibiotic-resistant bacteria and an ageing population of patients presenting with many comorbidities make it necessary to focus on this important topic.Diagnosis of PJI remains challenging because the clinical signs and symptoms and elevation of systemic biomarkers (C-reactive protein, erythrocyte sedimentation rate) may be unclear.In the last few years, the clinical research has focused on synovial fluid biomarkers as a possible breakthrough in the complex scenario of PJI diagnosis.Synovial biomarkers have shown encouraging results and they should be used as diagnostic adjuncts to synovial white cell count and culture bacteriology. Synovial leukocyte esterase (LE) and synovial C-reactive protein (CRP) have been evaluated as good screening measures; however, the most promising synovial fluid biomarker in terms of sensitivity and specificity for PJI seems to be alpha defensin (AD).The laboratory-based alpha defensin enzyme-linked immunosorbent assay (ELISA) test demonstrated the highest ever reported accuracy for PJI diagnosis. However, an alpha defensin lateral flow test could have its place in ruling in a suspected PJI intraoperatively because of its high specificity and rapid results. Cite this article: EFORT Open Rev 2019;4:10-13. DOI: 10.1302/2058-5241.4.180029.

Diagnosing Periprosthetic Joint Infection in Inflammatory Arthritis: Assumption Is the Enemy of True Understanding

BACKGROUND

Despite concern over the interpretation of serum and synovial fluid tests to screen and diagnose periprosthetic joint infection (PJI) in patients with inflammatory arthritis, only a single study has investigated this area. We aimed to assess accuracy of clinical and laboratory markers for PJI diagnosis in the context of underlying inflammatory arthritis.

METHODS

This multicenter study was conducted on total joint arthroplasty patients at 3 different centers between 2001 and 2016. PJI was defined based on Musculoskeletal Infection Society criteria. Acute PJI cases were excluded. Patients operated for a diagnosis other than infection, who did not subsequently fail at 1-year follow-up, were considered aseptic revisions. Serum C-reactive protein and erythrocyte sedimentation rate, synovial white blood cell and differential, as well as alpha-defensin and results of frozen section were documented.

RESULTS

In total, 1220 patients undergoing revision total joint arthroplasty (567 PJI, 653 aseptic) were included. Fifty-five septic patients and 61 in the aseptic group had inflammatory arthritis. Although mean levels of serum C-reactive protein and synovial white blood cell in inflammatory arthritis patients were significantly higher compared to patients without inflammatory arthritis, there were no significant differences in PJI patients. The thresholds associated with increased risk for PJI in patients with and without inflammatory arthritis were similar and closely resembled traditional cut-points.

CONCLUSION

We demonstrate higher baseline immune upregulation in aseptic revision cases with inflammatory arthritis, but no significant differences are seen for PJI. Conventional PJI thresholds for serum and synovial diagnostic markers should be adhered to. Assumptions about inflammatory arthritis patients needing differential diagnostic protocols should be avoided.

The proper timing of second-stage revision in treating periprosthetic knee infection: reliable indicators and risk factors

BACKGROUND

Two-stage revision is the standard procedure for periprosthetic knee infection. But when to perform the second-stage is still under debate. We attempt to search the reliable indicators, risk factors, and proper timing for the second-stage revision.

METHODS

We reviewed and followed 81 infected total knee arthroplasty patients who underwent two-stage revision from January 2010 to January 2014. Our cohort included 56 males and 25 females, all patients were confirmed as PJI with the same phenotypic cultures. The average age was 64.8 ± 8.21 (range 36-78) months. The mean follow-up time was 46.5 ± 17.6 (range 12-72) months after the second-stage surgeries. The diagnostic parameters including serum C-reaction protein, erythrocyte sedimentation rate, and intraoperative frozen section at the time of re-implantation were analyzed. The spacer detention time and antibiotic treatment time were compared.

RESULTS

Ten of them went through failed first- or second-stage surgeries. The overall success rate was 87.7%. The intraoperative frozen section is a good indicator at the time of re-implantation; the sensitivity and specificity is 90 and 83.1%. Serum CRP and ESR showed poor diagnostic value at time of re-implantation. Atypical pathogen infection, positive FS, and previous sinus were high-risk factors for failure of two-stage revision. Spacer detention time between 12 and 16 weeks had higher success rate than over 16 weeks.

CONCLUSION

The proper timing of re-implantation should be combined with disappearance of clinical symptoms and negative intraoperative FS with spacer detention time at 12 to 16 weeks.

Diagnostic Utility of Histological Analysis for Detecting Ongoing Infection During Two-Stage Revision Arthroplasty in Patients With Inflammatory Arthritis

BACKGROUND

Surgeons often rely on intra-operative histology (frozen sections [FS]) to determine the next step in surgical management during the second stage (re-implantation surgery) of 2-stage revision arthroplasty. The purpose of the study is to assess the accuracy of permanent sections (PS) and FS in the diagnosis of persistent infection during re-implantation in patients with an inflammatory arthritis.

METHODS

From 2001 to 2016, 47 planned second-stage revision total hip arthroplasty and total knee arthroplasty in patients with inflammatory arthritis were identified. Revisions were classified as having persistent infection if they were Musculoskeletal Infection Society positive at the time of second stage. PS or FS was considered to be positive for infection when at least one of the specimens demonstrated an acute inflammation. Receiver operating characteristic analysis was performed to obtain the diagnostic parameters.

RESULTS

There were 9 (19%) persistent infections. Both PS and FS had very high specificity (PS = FS = 94.7%). Sensitivity of PS was higher than FS, although not statistically significant (PS = 88.9%, FS = 55.6%, P = .083). Overall, PS had a better diagnostic utility than FS (area under the curve: PS vs FS = 0.92 vs 0.75, P = .045). Four specimens had discrepancies between PS and FS histology. In all 4 instances, the specimens were read as positive (infected) by PS, but negative by FS.

CONCLUSION

Histological analysis is recommended at the time of re-implantation surgery even in patients with inflammatory arthritis. PS had a better diagnostic utility than FS suggesting that areas of acute inflammation may be scattered and may not always be captured in the specimens taken for FS.

Diagnostic parameters in periprosthetic infections: the current state of the literature

Despite progress in recent years, a definitive diagnosis of PPI is not yet possible. Due to new diagnostic possibilities and the further development of already existing diagnostic tools, a more accurate diagnostic clarification of uncertain cases should be possible. The following article includes an overview of common existing diagnostic tools and instruments, which will likely gain importance in the future.

Intraoperative evaluation of polymorphonuclear leukocyte during second-stage revision surgery promote overdiagnosis of persistent periprosthetic joint infection

Objective

The aim of this study was to evaluate whether intraoperative histopathological examination could predict the risk of relapse of infection in periprosthetic joint infections (PJI).

Methods

The study included 25 patients (14 women and 11 men, with a mean age of 67.0 years (range, 37–83 years)), who had two-staged revision surgery for a PJI. Following prosthetic removal in the first stage, all patient underwent an intraoperative histopathological examination during the second stage. The patients were divided into PMNs-positive group (≥five PMNs per high-powered field) or -negative group (<five PMNs). A relapse was defined as the occurrence of PJI. Median follow-up was 51 months (range, 32–80 months) following second-stage revision surgery.

Results

Intraoperative histopathological revealed that 8.0% of cases were PMNs-positive. Postoperative histopathological examination revealed that 28.0% of cases were PMNs-positive. 28.0% of cases showed discrepancy between the PMNs-positivity. Intraclass correlation coefficient indicates poor reproducibility. Infection relapse after revision surgery occurred in two cases (8.0%); both relapse cases were from the PMNs-negative group. There was no statistical relationship between the presence of PMNs in periprosthetic tissue by intraoperative or postoperative histopathological examination and relapse of infection.

Conclusions

Our findings showed that intraoperative histopathological examination could not predict the relapse of infection. Intraoperative histopathological examination promotes overdiagnosis of the requirement for re-implantation of antibiotic-impregnated cement and prolonged treatment periods.

Level of evidence

Level III, diagnostic study

Diagnosis of Prosthetic Joint Infection: Cultures, Biomarker and Criteria

Prosthetic joint infections (PJIs) are devastating complications after joint arthroplasty that continue to pose a diagnostic challenge. Currently, a single, stand-alone test with the adequate accuracy and reliability for diagnosis of PJI is not available; therefore, physicians who care for patients with PJI must rely on a combination of diagnostic tests for the diagnosis of PJI. This article reviews conventional laboratory test modalities, diagnostic accuracy and limitations of current tests, and novel emerging tests for the diagnosis of PJI.

A Real Pain: Diagnostic Quandaries and Septic Arthritis

Rapid diagnosis and treatment of an infected joint are paramount in preserving orthopedic function. Here, we present a brief review of the many challenges associated with the diagnosis of both septic arthritis and prosthetic joint infections. We also discuss the many laboratory tests currently available to aid in the accurate diagnosis of joint infection, as well as emerging diagnostics that may have future utility in the diagnosis of these challenging clinical entities.

Diagnostic Methods for Prosthetic Joint Infection in Korea

Prosthetic joint infection (PJI) poses a burden on patients and health care resources. PJI diagnosis can be challenging, owing to imperfect definition, alongside inadequate diagnostic techniques. In this review, we describe consensus definitions of PJI, approaches to diagnosis using methods available in Korea, and novel diagnostic methods.

Rapid detection of periprosthetic joint infection using a combination of 16s rDNA polymerase chain reaction and lateral flow immunoassay: A Pilot Study

OBJECTIVES

The objective of this study was to develop a test for the rapid (within 25 minutes) intraoperative detection of bacteria from synovial fluid to diagnose periprosthetic joint infection (PJI).

METHODS

The 16s rDNA test combines a polymerase chain reaction (PCR) for amplification of 16s rDNA with a lateral flow immunoassay in one fully automated system. The synovial fluid of 77 patients undergoing joint aspiration or primary or revision total hip or knee surgery was prospectively collected. The cohort was divided into a proof-of-principle cohort (n = 17) and a validation cohort (n = 60). Using the proof-of-principle cohort, an optimal cut-off for the discrimination between PJI and non-PJI samples was determined. PJI was defined as detection of the same bacterial species in a minimum of two microbiological samples, positive histology, and presence of a sinus tract or intra-articular pus.

RESULTS

The 16s rDNA test proved to be very robust and was able to provide a result in 97% of all samples within 25 minutes. The 16s rDNA test was able to diagnose PJI with a sensitivity of 87.5% and 82%, and a specificity of 100% and 89%, in the proof-of-principle and validation cohorts, respectively. The microbiological culture of synovial fluid achieved a sensitivity of 80% and a specificity of 93% in the validation cohort.

CONCLUSION

The 16s rDNA test offers reliable intraoperative detection of all bacterial species within 25 minutes with a sensitivity and specificity comparable with those of conventional microbiological culture of synovial fluid for the detection of PJI. The 16s rDNA test performance is independent of possible blood contamination, culture time and bacterial species.Cite this article: V. Janz, J. Schoon, C. Morgenstern, B. Preininger, S. Reinke, G. Duda, A. Breitbach, C. F. Perka, S. Geissler. Rapid detection of periprosthetic joint infection using a combination of 16s rDNA polymerase chain reaction and lateral flow immunoassay: A Pilot Study. Bone Joint Res 2018;7:12-19. DOI: 10.1302/2046-3758.71.BJR-2017-0103.R2.

Evaluating the Use of Serum Inflammatory Markers for Preoperative Diagnosis of Infection in Patients with Nonunions

Purpose

The aim of this study is to evaluate the effectiveness of laboratory serum tests in the diagnosis of infected nonunion.

Methods

Forty-two patients suspected of having infected nonunion were investigated in the study. The serum levels of white blood-cell count (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and interleukin-6 (IL-6) were measured. A positive diagnosis of infection was made on the basis of the positive culture results. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each test were calculated.

Results

The sensitivity and specificity of CRP both were higher than IL-6: 60.0% versus 57.1% and 85.7% versus 57.1%, respectively. With one, two, three, and four positive tests, the predicted probabilities of infection were 66.7%, 90.9%, 100%, and 100%, respectively, but the number of patients who had three or four positive tests was small.

Conclusions

The diagnostic utility of IL-6 is inferior to CRP and the finding conflicts with previous conclusions drawn from periprosthetic infections. Laboratory analysis of serum inflammatory markers alone is not an effective screening tool for patients suspected of having an infected nonunion.

Novel porcine model of implant-associated osteomyelitis: A comprehensive analysis of local, regional, and systemic response

Pigs are favorable experimental animals for infectious diseases in humans. However, implant-associated osteomyelitis (IAO) models in pigs have only been evaluated using high-inoculum infection (>10⁸ CFU) models in 1975 and 1993. Therefore, the aim of this paper was to present a new low inoculum porcine model of human IAO based on 42 experimental pigs. The model was created by drilling an implant cavity in the tibial bone followed by insertion of a small steel implant and simultaneous inoculation of Staphylococcus aureus bacteria (n = 32) or saline (n = 10). The infected pigs were either inoculated with 10⁴ CFU (n = 26) or 10² and 10³ CFU (n = 6). All animals were euthanized 5 days after insertion of implants. Pigs receiving the high-inoculum infections showed a significantly higher volume of bone lesion, number of neutrophils around the implant, concentrations of acute phase proteins in serum, and enlargement of regional lymph nodes. A positive correlation was present between a high number of surrounding neutrophils and high values of all other parameters. Furthermore, a threshold of 40 neutrophils per 10 high power fields for the histopathological diagnosis of high grade IAO was defined.

IN CONCLUSION

This paper describes a novel low-inoculum S. aureus porcine model of IAO which was demonstrated to be reliable, reproducible and discriminative to human IAO, and represents a requested and valuable tool in orthopedic research. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2211-2221, 2017.