Limited Predictive Value of Serum Inflammatory Markers for Diagnosing Fracture-Related Infections: results of a large retrospective multicenter cohort study

Proceedings of the United Kingdom Periprosthetic Joint Infection Meeting 2022: Fracture-Related Infection Session

Implant-related infections represent a relatively common and significant challenge in the surgical management of musculoskeletal trauma patients. The third United Kingdom Periprosthetic Joint Infection (UK PJI) Meeting convened in Glasgow on 1 April 2022, and brought together over 180 delegates, representing orthopaedics, infectious diseases, microbiology, plastic surgery, anaesthetics, and allied health professions, including pharmacy and specialist nurses. The meeting comprised a plenary session for all delegates, and separate breakout sessions for fracture-related infection (FRI) and arthroplasty. The UK PJI working group prepared consensus statements in advance of each session, based upon topics that were discussed at previous meetings, and delegates engaged in an anonymous electronic voting process. This article presents the findings of the FRI session, and examines each consensus topic within the context of the contemporary literature.

The value of current diagnostic techniques in the diagnosis of fracture-related infections: Serum markers, histology, and cultures

Although fracture-related infection (FRI) is a serious complication following bone fractures, a comprehensive definition and diagnostic criteria have only emerged in recent years. According to this consensus definition, the diagnosis of FRI is based on preoperative and intraoperative suggestive or confirmatory criteria. Serum markers, histology, and microbiological cultures are considered to play a crucial role in the FRI diagnostic pathway. However, at the time of publication of the FRI consensus definition in 2018 and its update in 2020, limited data was available on the accuracy of these diagnostic methods. This review aims to provide an overview of recent publications and discuss whether new evidence has been obtained regarding the value of these current diagnostic techniques. Meanwhile, several studies have confirmed the limited prognostic value of C-reactive protein, erythrocyte sedimentation ratio, and white blood cell count. Other serologic markers for preoperative diagnosis of FRI with promising diagnostic performance are d-dimer, plasma fibrinogen, platelet count to mean platelet volume ratio, and a risk prediction model that includes soft tissue injury type and fracture complexity in addition to blood markers. However, their true diagnostic value in daily clinical practice needs to be investigated in further studies. Data on histology in FRI diagnosis is still limited, but its potential as a confirmatory criterion seems to lie in its high specificity. Recent studies indicate that tissue culture exhibits moderate sensitivity and high specificity, with sensitivity improvements achieved by sampling of five specimens and long-term culture. Implant sonication also appears to enhance the sensitivity of culture and the detection rate of polymicrobial infections. In conclusion, the true value of diagnostic techniques is difficult to assess, in part because it is measured against a gold standard that is itself imperfect and still evolving, but also because of methodological differences in sample processing or the use of different thresholds. Nevertheless, this review has identified that the value of current diagnostic techniques is high when used in combination. To draw more accurate conclusions about the value of serum markers, histology, and culture including sonication, future studies should be prospective and utilize a greater standardization in sampling and methodological protocols.

Clinical management and innovation in fracture non-union

INTRODUCTION

With the introduction and continuous improvement in operative fracture fixation, even the most severe bone fractures can be treated with a high rate of successful healing. However, healing complications can occur and when healing fails over prolonged time, the outcome is termed a fracture non-union. Non-union is generally believed to develop due to inadequate fixation, underlying host-related factors, or infection. Despite the advancements in fracture fixation and infection management, there is still a clear need for earlier diagnosis, improved prediction of healing outcomes and innovation in the treatment of non-union.

AREAS COVERED

This review provides a detailed description of non-union from a clinical perspective, including the state of the art in diagnosis, treatment, and currently available biomaterials and orthobiologics.Subsequently, recent translational development from the biological, mechanical, and infection research fields are presented, including the latest in smart implants, osteoinductive materials, and in silico modeling.

EXPERT OPINION

The first challenge for future innovations is to refine and to identify new clinical factors for the proper definition, diagnosis, and treatment of non-union. However, integration of in vitro, in vivo, and in silico research will enable a comprehensive understanding of non-union causes and correlations, leading to the development of more effective treatments.

Fracture-related infection blood-based biomarkers: Diagnostic strategies

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

Proteomic Analyses of Plasma From Patients With Fracture-Related Infection Reveals Systemic Activation of the Complement and Coagulation Cascades

OBJECTIVES

The objective of this study was to compare plasma proteomes of patients with confirmed fracture-related infections (FRIs) matched to noninfected controls using liquid chromatography-mass spectrometry.

METHODS

DESIGN

This was a prospective case-control study.

SETTING

The study was conducted at a single, academic, Level 1 trauma center.

PATIENT SELECTION CRITERIA

Patients meeting confirmatory FRI criteria were matched to controls without infection based on fracture region, age, and time after surgery from June 2019 to January 2022. Tandem mass tag liquid chromatography-mass spectrometry analysis of patient plasma samples was performed.

OUTCOME MEASURES AND COMPARISONS

Protein abundance ratios in plasma for patients with FRI compared with those for matched controls without infection were calculated.

RESULTS

Twenty-seven patients meeting confirmatory FRI criteria were matched to 27 controls. Abundance ratios for more than 1000 proteins were measured in the 54 plasma samples. Seventy-three proteins were found to be increased or decreased in patients with FRI compared with those in matched controls (unadjusted t test P < 0.05). Thirty-two of these proteins were found in all 54 patient samples and underwent subsequent principal component analysis to reduce the dimensionality of the large proteomics dataset. A 3-component principal component analysis accounted for 45.7% of the variation in the dataset and had 88.9% specificity for the diagnosis of FRI. STRING protein-protein interaction network analysis of these 3 PCs revealed activation of the complement and coagulation cascades through the Reactome pathway database (false discovery rates <0.05).

CONCLUSIONS

Proteomic analyses of plasma from patients with FRI demonstrate systemic activation of the complement and coagulation cascades. Further investigation along these lines may help to better understand the systemic response to FRI and improve diagnostic strategies using proteomics.

LEVEL OF EVIDENCE

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

Fracture-related infection in revision proximal femoral intramedullary nails

BACKGROUND

The proximal femoral nail is a commonly used fixation device for extra-capsular neck of femur fractures at our UK NHS Trust. Fracture-related infection (FRI) is a catastrophic complication that can be associated with internal fixation. FRI is often diagnosed late, and causes significant impact on the patient and healthcare system, leading to extended hospital stays, reduced quality of life, high healthcare costs and increased mortality and morbidity.

AIM

This study aims to evaluate whether failed proximal femoral nails treated at a major trauma centre in the United Kingdom are undergoing routine intraoperative microbiology sampling, as outlined by the FRI Consensus Group in 2020, and also to establish how often fracture-related infection is present in failed proximal femoral nails.

METHOD

Electronic patient record systems were reviewed over a 4-year period between 2018-2022 to identify patients who had a proximal femoral nailing, and those who required revision surgery. From this cohort, we then identified whether sampling had taken place during revision surgery, and the number of samples taken.

RESULTS

1041 proximal femoral nails were performed at our trust during the 4-year period. 60 of these implants failed, with 52 of these undergoing revision surgery at our hospital.  Only 56% cases had intra-operative samples taken for microbiology testing, with an average of 9 samples sent per case. Intra-operative sampling confirmed infection in 25% of cases with samples sent.  Of the cases requiring ≥ 3 operations, 75% of cases had confirmed infection.

DISCUSSION

The data shows that more can be done to ensure earlier diagnosis of fracture-related infection in failed proximal femoral nails. We should have a high suspicion of FRI in this cohort of patients. This study highlights the importance of a standardised protocol to ensure routine intra-operative sampling during proximal femoral nail revision surgery.

The Role of Combined Inflammatory Biomarkers in the Diagnosis of High- and Low-Virulence FRI Among High-Risk Lower Extremity Fractures

Objective

The aim of this study is to evaluate the diagnostic accuracy of infection-related biomarkers in high-risk lower limb injury patients with fracture-related infection (FRI) caused by high-/low-virulence microorganisms.

Methods

This study was a retrospective analysis of patients with high-risk lower extremity fractures (including tibial plateau, calcaneus, and Pilon fractures) who underwent open reduction internal fixation (ORIF) surgery from January 2017 to February 2022. Peripheral blood samples were collected within 24 hours of admission, and the following information was evaluated: gender, age, BMI, smoking, comorbidities, injury information, surgical details, values for serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), as well as neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and platelet-to-lymphocyte ratio (PLR).

Results

A total of 576 patients receiving lower extremity fracture surgery were included in this study. Fifty-one patients (8.85%) were identified as FRI, and 28 (54.9%) of these 51 cases were further classified as high-virulence group. The median levels of CRP, ESR, NLR, and MLR were significantly higher in the FRI group than in the non-FRI group (p < 0.01). Similarly, the marginally significantly higher levels of CRP and NLR presented in the high-virulence group, compared to the low-virulence group (p < 0.1). The AUC areas of CRP, NLR, and CRP+NLR were 0.826, 0.650, and 0.873, respectively. We calculated the optimal cut-off points for CRP+NLR as diagnostic markers of high-virulent infection was 0.377.

Conclusion

This study showed the incidence of FRI in high-risk lower extremity fractures was 8.9%, and identified preoperative serum biomarkers, including CRP, ESR, NLR, and PLR, as useful tools for assisting in the diagnosis of infection. Additionally, the combination of CRP with NLR played a discriminating clinical role in postoperative infections caused by different virulence.

Level of Evidence

Clinical study.

Outcome and risk factors for recurrence of early onset fracture-related infections treated with debridement, antibiotics and implant retention: Results of a large retrospective multicentre cohort study

INTRODUCTION

Early Fracture-Related Infections (FRIs) are a common entity in hospitals treating trauma patients and are often treated with a Debridement, Antibiotics and Implant Retention (DAIR) procedure. Aims of this study were to 1) evaluate the recurrence rate after DAIR procedures for early onset FRI, 2) establish the number of surgical procedures to gain control of the initial infection and 3) identify independent predictors for recurrence in this cohort.

METHODS

A retrospective multicentre cohort study was conducted in two level 1 trauma centres. Consecutive patients who underwent a DAIR procedure between January 1st 2015 and July 1st 2020 for confirmed FRI with an onset of <6 weeks after the latest osseous operation were included. Recorded data included patient demographics, treatment characteristics and follow-up. Univariate and multivariate logistic regression analyses were performed to assess predictors for recurrent FRI.

RESULTS

A total of 141 patients with early FRI were included in this study with a median age of 54.0 years (interquartile range (IQR) 34.5-64.0). The recurrence rate of FRI was 13% (n = 19) at one year follow-up and 18% (n = 25) at 23.1 months (IQR 15.3-36.4) follow-up. Infection control was achieved in 94% (n = 127/135) of cases. In total, 73 patients (52%) underwent at least two surgical procedures to treat the ongoing initial episode of FRI, of whom 54 patients (74%) required two to three procedures and 17 patients (23%) four to five procedures. Predictors for recurrent FRI were use of an intramedullary nail during index operation (odds ratio (OR) 4.0 (95% confidence interval (CI) 1.1-13.8)), need for additional surgical procedures to treat ongoing infection during the treatment period following the first presentation of early FRI (OR 1.9 (95% CI 1.1-3.5)) and a decreased Injury Severity Score (ISS) (inverted OR 1.1 (95% CI 1.0-1.1)).

CONCLUSION

The recurrence rate after treatment of early onset FRI in patients treated with a DAIR procedure was 18% at 23.1 months follow-up. At least two surgical procedures to gain control of the initial infection were needed in 52% of patients. Independent predictors for recurrent FRI were the use of an intramedullary nail during index operation, need for additional surgical procedures and a decreased ISS.

Serology and Comorbidities in Patients With Fracture Nonunion: A Multicenter Evaluation of 640 Patients

INTRODUCTION

This multicenter cohort study investigated the association of serology and comorbid conditions with septic and aseptic nonunion.

METHODS

From January 1, 2011, to December 31, 2017, consecutive individuals surgically treated for nonunion were identified from seven centers. Nonunion-type, comorbid conditions and serology were assessed.

RESULTS

A total of 640 individuals were included. 57% were male with a mean age of 49 years. Nonunion sites included tibia (35.2%), femur (25.6%), humerus (20.3%), and other less frequent bones (18.9%). The type of nonunion included septic (17.7%) and aseptic (82.3%). Within aseptic, nonvascular (86.5%) and vascular (13.5%) nonunion were seen. Rates of smoking, alcohol abuse, and diabetes mellitus were higher in our nonunion cohort compared with population norms. Coronary artery disease and tobacco use were associated with septic nonunion (P < 0.05). Diphosphonates were associated with vascular nonunion (P < 0.05). Serologically, increased erythrocyte sedimentation rate, C-reactive protein, parathyroid hormone, red cell distribution width, mean platelet volume (MPV), and platelets and decreased absolute lymphocyte count, hemoglobin, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and albumin were associated with septic nonunion while lower calcium was associated with nonvascular nonunion (P < 0.05). The presence of four or more of increased erythrocyte sedimentation rate, C-reactive protein, or red cell distribution width; decreased albumin; and age younger than 65 years carried an 89% positive predictive value for infection. Hypovitaminosis D was seen less frequently than reported in the general population, whereas anemia was more common. However, aside from hematologic and inflammatory indices, no other serology was abnormal more than 25% of the time.

DISCUSSION

Abnormal serology and comorbid conditions, including smoking, alcohol abuse, and diabetes mellitus, are seen in nonunion; however, serologic abnormalities may be less common than previously thought. Septic nonunion is associated with inflammation, younger age, and malnourishment. Based on the observed frequency of abnormality, routine laboratory work is not recommended for nonunion assessment; however, specific focused serology may help determine the presence of septic nonunion.

Fracture Related Infections and Their Risk Factors for Treatment Failure—A Major Trauma Centre Perspective

Fracture related infections (FRI) are debilitating and costly complications of musculoskeletal trauma surgery that can result in permanent functional loss or amputation. Surgical treatment can be unsuccessful, and it is necessary to determine the predictive variables associated with FRI treatment failure, allowing one to optimise them prior to treatment and identify patients at higher risk. The clinical database at a major trauma centre was retrospectively reviewed between January 2015 and January 2021. FRI treatment failure was defined by infection recurrence or amputation. A univariable logistic regression analysis was performed, followed by a multivariable regression analysis for significant outcomes between groups on univariable analysis, to determine risk factors for treatment failure. In total, 102 patients were identified with a FRI (35 open, 67 closed fractures). FRI treatment failure occurred in 24 patients (23.5%). Risk factors determined by our multivariate logistic regression model were obesity (OR 2.522; 95% CI, 0.259–4.816; p = 0.006), Gustilo Anderson type 3c (OR 4.683; 95% CI, 2.037–9.784; p = 0.004), and implant retention (OR 2.818; 95% CI, 1.588–7.928; p = 0.041). Given that FRI treatment in 24 patients (23.5%) ended up in failure, future management need to take into account the predictive variables analysed in this study, redirect efforts to improve management and incorporate adjuvant technologies for patients at higher risk of failure, and implement a multidisciplinary team approach to optimise risk factors such as diabetes and obesity.

Does the pre-operative neutrophil-lymphocyte ratio have a predictive value in detecting infection in type 3 open tibia diaphysis fractures?

BACKGROUND

This retrospective study was aimed to investigate whether the pre-operative neutrophil-lymphocyte (N/L) ratio has a predictive value in terms of evaluating the development of infection in patients with type 3 open fractures of the tibia diaphysis.

METHODS

A total of 72 patients with type 3 open tibia fractures who consulted to the emergency service at the Necmettin Er-bakan University Meram Faculty of Medicine, during the period between 2015 and 2020 were retrospectively examined. A total of 39 patients who underwent external fixator in the first treatment were included in the study. The information pertaining to the patients such as the patient demographic data, type of injury, wound cultures, and N/L rates during the pre-operative period were recorded. Patients were divided into two groups based on the presence of infection: Group 1 (12 patients) consisted of patients who had infec-tion, and Group 2 (27 patients) consisted of patients who had no infection.

RESULTS

34 (87.2%) of the patients were male and 5 (12.8%) were women. The mean age of these patients was 43.18±18.67 (19-80). Infection was detected in 12 (30.8%) out of 39 patients. Of these patients, 9 (75%) were monomicrobial, and 3 (25%) were polymicrobial. The most common mechanism of the injury was gunshot injury in 16 (41%) of all patients. However, there was no sig-nificant difference between the groups in terms of mechanism of injury (p=0.445). When all patients were examined in terms of N/L rates and presence of infection, there was no significant difference between Group 1 and Group 2 (p=0.976).

CONCLUSION

Although N/L ratio of the blood in the pre-operative period has a predictive value for chronic diseases, we believe that it has no predictive value for detecting infection in patients with type 3 acute open tibia fractures.

Altered Gut Microbiota as an Auxiliary Diagnostic Indicator for Patients With Fracture-Related Infection

Preoperative diagnosis of fracture-related infection (FRI) is difficult for patients without obvious signs of infection. However, specific profiles of gut microbiota may be used as a potential diagnostic tool for FRI as suggested by a previous study. The fecal microbiome was compared between 20 FRI patients (FRI group), 18 fracture healed patients (FH group), and 12 healthy controls (HC group) included after collection of fecal samples and evaluation. The α and β diversity indices were used to characterize the fecal microbiome. Dysbiosis indexes were constructed based on the characteristic high-dimensional biomarkers identified in the fecal microbiota from the three groups by linear discriminant analysis and generalized linear model analysis to quantify the dysbiosis of fecal microbiota. The effectiveness of α and β diversity indices and dysbiosis indexes was assessed in distinguishing the fecal microbiome among the three groups. The influences of serum inflammatory factors on gut microbiota were also addressed. The α diversity indices were significantly different between the three groups, the highest in HC group and the lowest in FRI group (P < 0.05). The β diversity indices showed significant phylogenetic dissimilarity of gut microbiome composition among the three groups (P < 0.001). The dysbiosis indexes were significantly higher in FRI group than in FH and HC groups (P < 0.001). The area under Receiver operating characteristic curve showed the characteristics of gut microbiota and the gut microbiota was found as effective in distinguishing the three groups. The dysbiosis in the FRI patients was associated with systemic inflammatory factors. In addition, significant differences in the gut microbiota were not observed between the FRI patients versus without sinus tract or pus before operation. Since FRI patients, with or without sinus tract or pus, have a characteristic profile of gut microbiota, their gut microbiota may be used as an auxiliary diagnostic tool for suspected FRI.

Interleukin-6 versus Common Inflammatory Biomarkers for Diagnosing Fracture-Related Infection: Utility and Potential Influencing Factors

Currently, the utility of white blood cell count (WBC), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), for diagnosis of fracture-related infection (FRI), is still controversial, and potential efficiency of interleukin-6 (IL-6) as a novel cytokine in assisted diagnosis of FRI remains unclear. This study is aimed at investigating the utility and potential influencing factors of IL-6 and the common biomarkers for diagnosing FRI. Preoperative serological levels of IL-6 and the three biomarkers were compared between 407 FRI patients and 195 fracture-healed (FH) patients. Diagnostic efficiency of the indicators was evaluated using the areas under the receiver operating characteristic (ROC) curves, and their potential influencing factors were also analyzed. Outcomes showed that the median levels of all of the four biomarkers were significantly higher among the FRI patients than those among the FH patients (P < 0.01). The areas below the ROC curves of ESR, CRP, and IL-6 were 76.5%, 76.4%, and 71.8%, respectively, with WBC of only 56.9%. Compared with ESR and CRP, IL-6 displayed a lower sensitivity (ESR vs. CRP vs. IL − 6 = 72.7% vs. 65.6% vs. 57.5%) but a higher specificity (ESR vs. CRP vs. IL − 6 = 70.3% vs. 75.4% vs. 83.6%). Serological IL-6 level was influenced by pathogen culture result and pathogen number; nonetheless, bacteria type appeared to have no influence on the levels of the four biomarkers. In short, this study displayed similar value of IL-6 with that of ESR and CRP in assisted diagnosis of FRI. Whether IL-6 can be regarded as a promising diagnostic indicator requires more studies.

The value of conventional radiographs for diagnosing internal fixation-associated infection

Background

The aim of the study is to  assess the diagnostic value of preoperative conventional radiographs for diagnosing infection associated with internal fixation devices.

Methods

We prospectively collected data of patients undergoing removal of internal fixation devices for any reason. Infection was diagnosed in case of purulence, sinus tract, positive histopathology and/or positive peri-implant tissue or sonication fluid culture. In radiographs radiolucent lines, implant breakage or displacement, or periosteal reaction were assessed. White blood cell count (WBC) and serum C-reactive protein (CRP) were determined at admission.

Results

We included 421 surgeries in 380 patients (median age 53.6 years, range 11–98 years), mainly indicated for infection (24.9%), nonunion (20.0%) and symptomatic implants (13.5%). Radiologic signs of infection included radiolucent lines (11.4%); implant breakage (12.4%) or displacement (10.7%); and periosteal reaction (7.1%). Infection was confirmed in 116 cases (27.6%). Only radiolucent lines (OR = 1.86 [95%CI: 1.00–3.38]) and periosteal reaction (OR = 2.48 [95%CI: 1.17–5.26]) were associated with infection, with a low sensitivity (16.4 and 12.1%, respectively), and high specificity (90.5 and 94.8%, respectively). Preoperative WBC and CRP had a sensitivity of 23.0 and 35.3%, and specificity of 91.7 and 89.5%, respectively.

Conclusions

Radiological signs suggestive of infection were uncommon. Radiolucency and periosteal reaction were associated with infection, though with low sensitivity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04170-3.

Definition and diagnosis of fracture-related infection

Fracture-related infection (FRI) is common and often diagnosed late.Accurate diagnosis is the beginning of effective treatment.Diagnosis can be difficult, particularly when there are no outward signs of infection.The new FRI definition, together with clear protocols for nuclear imaging, microbiological culture and histological analysis, should allow much better study design and a clearer understanding of infected fractures.In recent years, there has been a new focus on defining FRI and avoiding non-specific, poorly targeted treatment. Previous studies on FRI have often failed to define infection precisely and so are of limited value. This review highlights the essential principles of making the diagnosis and how clinical signs, serum tests, imaging, microbiology, molecular biology and histology all contribute to the diagnostic pathway. Cite this article: EFORT Open Rev 2020;5:614-619. DOI: 10.1302/2058-5241.5.190072.

[Diagnostics and classification of non-unions]

BACKGROUND

Non-union is defined as an insufficiently consolidated fracture in which healing without a surgical intervention is no longer foreseeable. Several underlying predispositions and factors have to be taken into account in order to optimize the diagnostics, classification and surgical treatment of this complex and challenging pathology.

OBJECTIVE

As the patient-specific optimized treatment sometimes pursues different goals depending on the specific subtype of non-union, an agreement on the most important parameters within the framework of a standardized classification is of crucial importance. In addition to established diagnostic algorithms, this article also describes modern radiologic diagnostic methods.

MATERIAL AND METHODS

In addition to the clinical examination, the diagnostics of non-union are mainly based on radiological imaging using X‑ray or computed tomography. Complex fracture morphology or uncertainty, particularly regarding the infection status and perfusion of non-union, can be an indication for an extension of the diagnostics using contrast-enhanced ultrasound (CEUS) or dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

CONCLUSION

A practicable and precise classification of the different types of non-union can only be successful based on a focussed diagnostic procedure using radiologic and functional diagnostic tools, which guide the surgeon in establishing the optimal treatment. This also includes modern functional imaging examinations, such as CEUS and DCE-MRI.

Limited diagnostic value of serum inflammatory biomarkers in the diagnosis of fracture-related infections

AIMS

The aim of this study was to evaluate the diagnostic value of preoperative serum CRP, white blood cell count (WBC), percentage of neutrophils (%N), and neutrophil to lymphocyte ratio (NLR) when using the fracture-related infection (FRI) consensus definition.

METHODS

A cohort of 106 patients having surgery for suspected septic nonunion after failed fracture fixation were studied. Blood samples were collected preoperatively, and the concentration of serum CRP, WBC, and differential cell count were analyzed. The areas under the curve (AUCs) of diagnostic tests were compared using the z-test. Regression trees were constructed and internally cross-validated to derive a simple diagnostic decision tree.

RESULTS

Using the FRI consensus definition, 46 patients (43%) were identified as infected. Sensitivity, specificity, and AUC of CRP were 67% (95% confidence interval (CI) 52% to 80%), 61% (95% CI 47% to 74%), and 0.64 (95% CI 0.54 to 0.74); of WBC count were 17% (95% CI 9% to 31%), 95% (95% CI 86% to 99%), and 0.57 (95% CI 0.50 to 0.62); of %N 13% (95% CI 6% to 26%), 87% (95% CI 76% to 93%), and 0.50 (95% CI 0.43 to 0.56); and of NLR 28% (95% CI 17% to 43%), 80% (95% CI 68% to 88%), and 0.54 (95% CI 0.46 to 0.63), respectively. A better performance of serum CRP was shown in comparison to the leucocyte count (p = 0.006), %N (p < 0.001), and NLR (p = 0.001). A statistically lower serum CRP level was shown in patients with an infection caused by a low virulence microorganism in comparison to high virulence bacteria (p = 0.008). We found that a simple decision tree approach using only low serum neutrophils (< 3.615 × 10⁹/l) and low CRP (< 2.45 mg/l) may allow better identification of aseptic cases.

CONCLUSION

The evaluated serum inflammatory markers showed limited diagnostic value in the preoperative diagnosis of FRI when using the uniform FRI Consensus Definition. Therefore, they should remain as suggestive criteria in diagnosing FRI. Although CRP showed a higher performance in comparison to the other serum markers, it is insufficiently accurate to diagnose a septic nonunion, especially when caused by low virulence microorganisms. Cite this article: Bone Joint J 2020;102-B(7):904-911.

The infected fracture: can we agree on standard definitions?

A precise definition of infection after fracture fixation is essential for the evaluation of published research data and for the future establishment of uniform treatment concepts. Recently, a multidisciplinary expert panel has developed a consensus definition that includes 4 confirmatory criteria for infection following fracture fixation. These criteria are: Fistula, sinus, or wound breakdown; purulent drainage or deep purulence at surgery; positive cultures from at least 2 separate deep tissue/implant specimens taken during an operative intervention; and microorganisms in deep tissue specimens confirmed by histopathological staining. The consensus panel also identified 6 categories of suggestive criteria which are features associated with infection that requires further investigation.

Erythrocyte Sedimentation Rate and C-Reactive Protein in Acute Inflammation

OBJECTIVES

To assess the diagnostic accuracy of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in acute inflammation.

METHODS

PubMed and Scopus were searched and eligible articles were screened for methodologic quality using the Quality Assessment of the Diagnostic Accuracy Studies-Revised. Meta-analysis with calculation of pooled sensitivity (Se), specificity (Sp), and summary area under the curve (SAUC) was performed.

RESULTS

Twenty-nine studies were eligible. Se and Sp were 0.78 and 0.68 (SAUC = 0.80) for ESR in orthopedic infections and 0.79 and 0.70 (SAUC = 0.81) for CRP. For the diagnosis of other various inflammatory conditions, CRP had a superior diagnostic accuracy, with a Se of 0.86, Sp of 0.67, and SAUC of 0.86 compared with a Se of 0.77, Sp of 0.59, and SAUC of 0.75 for ESR. Heterogeneity among studies was elevated. Combined use of ESR and CRP yielded higher diagnostic accuracy.

CONCLUSIONS

Despite observed heterogeneity among studies, ESR and CRP have a similar diagnostic accuracy in assessment of inflammation, especially in orthopedic conditions.

Fever and Erythema are Specific Findings in Detecting Infection Following Total Knee Arthroplasty

Current diagnostic modalities are based almost exclusively on laboratory findings and the role of clinical presentation remains unknown. The purpose of this study was to examine the diagnostic value of clinical presentation in detecting periprosthetic joint infection (PJI). This study evaluated 279 patients undergoing revision surgery for failed total knee arthroplasty (TKA) between 2001-2016. Patients were classified as undergoing septic revisions based on major MSIS criteria. Aseptic revisions were defined as cases of single stage revision that did not have suspected PJI, fulfill MSIS criteria, or subsequently fail within one year of follow-up. Clinical presentation included pain, fever, presence of joint effusion or erythema, and reduced range of motion. Serum and synovial laboratory markers were also evaluated. The diagnostic value of each test was assessed and a Fagan's nomogram was constructed. A subset of MSIS-negative patients was used to demonstrate the value of various clinical presentations in detecting PJI. Post-test probability for infection was calculated taking into account clinical presentation together with serum and synovial markers. Our results show that fever and erythema are the most important signs for diagnosing PJI with a positive likelihood ratio (LR) of 10.78 and 8.08, respectively. Effusion had a LR of 2.42. Pain and reduced ROM were not as strongly correlated with PJI diagnosis; LR was 1.02 and 1.51. Of the 35 MSIS-negative patients treated for PJI, 33 had a post-test probability of infection greater than 90% when taking clinical presentation into account. Clinical presentation should be used to guide which future diagnostic tests should be ordered and in the interpretation of their results. Our results indicate that pain, fever, presence of joint effusion or erythema, and reduced range of motion should prompt further workup for infection. We propose a nomogram that may be used in interoperating their individual weight together with laboratory findings. Fever and erythema are highly specific findings in patients with PJI and future studies should assess whether they may be added as minor criteria to current definitions for infection.

Brodie's Abscess: A Systematic Review of Reported Cases

Introduction: Brodie's abscess is a form of osteomyelitis. Since its first appearance in the medical literature in 1832, numerous cases have been described. The aim of this article is to provide the first comprehensive overview of published cases of Brodie's abscess, and to describe diagnostic methods, therapeutic consequences and outcomes.

Methods: According to PRISMA guidelines a systematic review of the literature was performed. All published data in English or Dutch were considered for inclusion with no limitations on publication date. Data was extracted on demography, duration of symptoms, signs of inflammation, diagnostic imaging, causative agent, treatment and follow-up.

Results: A total of 70 articles were included, reporting on a total of 407 patients, mostly young (median age 17) males (male:female ratio 2.1:1). The median duration of symptoms before diagnosis was 12 weeks (SD 26). Mostly consisting of pain (98%) and/or swelling (53%). 84% of all patients were afebrile, and less than 50% had elevated serum inflammation markers. Diagnosis was made with a combination of imaging modalities: plain X-ray in 96%, MRI (16%) and CT-scan (8%). Treatment consisted of surgery in 94% of the cases, in conjunction with long term antibiotics in 77%. Staphylococcus aureus was the pathogen most often found in the culture (67,3%). Outcome was generally reported as favorable. Recurrence was reported in 15,6% of the cases requiring further intervention. Two cases developed permanent disability.

Conclusion: Brodie's abscess has an insidious onset as systemic inflammatory signs and symptoms were often not found. Treatment consisted mostly of surgery followed by antibiotics (77%) or only surgery (17%) and outcomes were generally reported as favourable.

Diagnostic accuracy of serum inflammatory markers in late fracture-related infection: a systematic review and meta-analysis

AIMS

To assess the diagnostic value of C-reactive protein (CRP), leucocyte count (LC), and erythrocyte sedimentation rate (ESR) in late fracture-related infection (FRI).

MATERIALS AND METHODS

PubMed, Embase, and Cochrane databases were searched focusing on the diagnostic value of CRP, LC, and ESR in late FRI. Sensitivity and specificity combinations were extracted for each marker. Average estimates were obtained using bivariate mixed effects models.

RESULTS

A total of 8284 articles were identified but only six were suitable for inclusion. Sensitivity of CRP ranged from 60.0% to 100.0% and specificity from 34.3% to 85.7% in all publications considered. Five articles were pooled for meta-analysis, showing a sensitivity and specificity of 77.0% and 67.9%, respectively. For LC, this was 22.9% to 72.6%, and 73.5% to 85.7%, respectively, in five articles. Four articles were pooled for meta-analysis, resulting in a 51.7% sensitivity and 67.1% specificity. For ESR, sensitivity and specificity ranged from 37.1% to 100.0% and 59.0% to 85.0%, respectively, in five articles. Three articles were pooled in meta-analysis, showing a 45.1% sensitivity and 79.3% specificity. Four articles analyzed the value of combined inflammatory markers, reporting an increased diagnostic accuracy. These results could not be pooled due to heterogeneity.

CONCLUSION

The serum inflammatory markers CRP, LC, and ESR are insufficiently accurate to diagnose late FRI, but they may be used as a suggestive sign in its diagnosis.