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Objectives Knowledge of the microbiological aetiology of periprosthetic joint infection (PJI) is essential to its management. Contemporary literature from the United States on this topic is lacking. This study aimed to identify the most common microorganisms associated with types of arthroplasty, the timing of infection, and clues to polymicrobial infection. Methods We performed an analytical cross-sectional study of patients 18 years of age or older with hip or knee PJI diagnosed at our institution between 2010 and 2019. PJI was defined using the criteria adapted from those of the Musculoskeletal Infection Society. Cases included PJI associated with primary or revision arthroplasty and arthroplasty performed at our institution or elsewhere. Results A total of 2067 episodes of PJI in 1651 patients were included. Monomicrobial infections represented 70% of episodes (n = 1448), with 25% being polymicrobial (n = 508) and the rest (5%, n = 111) culture-negative. The most common group causing PJI was coagulase-negative Staphylococcus species (other than S. ludgunensis) (37%, n = 761). The distribution of most common organisms was similar regardless of arthroplasty type. The S. aureus complex, Gram-negative bacteria, and anaerobic bacteria (other than Cutibacterium species) were more likely to be isolated than other organisms in the first year following index arthroplasty (OR 1.7, 95%CI 1.4–2.2; OR 1.5, 95%CI 1.1–2.0; and OR 1.5, 95%CI 1.0–2.2, respectively). The proportion of culture-negative PJIs was higher in primary than revision arthroplasty (6.5% versus 3%, p 0.0005). The presence of a sinus tract increased the probability of the isolation of more than one microorganism by almost three-fold (OR 2.6, 95%CI 2.0–3.3). Conclusions Joint age, presence of a sinus tract, and revision arthroplasties influenced PJI microbiology.

Purpose The clinical utility of echocardiography in the setting of a positive blood culture in paediatric patients presenting with osteomyelitis (OM) and/or septic arthritis (SA). Methods Retrospective review between 2013 and 2019: Patients < 18 years with OM, SA or combined infection (OM+SA) were included. Patients were excluded for immunodeficiency, loss of follow-up or penetrating infection. Charts with positive blood cultures were reviewed for echocardiography on that admission. Demographic variables were compared utilizing the Student's t-test and Fisher's exact test. A multivariable linear regression model was constructed to examine the association between echocardiography and length of stay, controlling for age, sex, fever, white blood cell (WBC) on admission, antibiotic administration and surgery performed. Results Of 157 patients with OM, SA or combined infection, 44 had a positive blood culture. In all, 26 had an echocardiogram, and none showed endocarditis. Echocardiography was independently associated with a 6.2-day length of stay increase. WBC count and surgical intervention demonstrated a trend toward significance in length of stay, with each WBC unit increase associated with a 0.53-day increase. Surgical intervention was associated with an average 6.3-day length of stay decrease. Conclusion No patient had a positive echocardiogram, and no changes in management were initiated. However, an echocardiogram increased stay by 6.2 days. In addition to costs associated with increased stay, patients were billed between $1460 and $1700 per echocardiogram. The utility of echocardiograms in the setting of bacteremia associated with musculoskeletal infections in the paediatric population should be re-examined, and guidelines should be updated to reflect the cost-benefit analysis. Level of Evidence III

Appropriate use criteria (AUC) are statements that contain indications describing when and how often an intervention should be performed under the optimal combination of scientific evidence, clinical judgment, and patient values while avoiding unnecessary provisions of services. Society of Nuclear

Introducción: El objetivo del estudio fue analizar la supervivencia sin recurrencia de infección en pacientes con reemplazo total de cadera tratados con revisión en dos tiempos, valorando el impacto del cultivo intraoperatorio y la congelación positiva en el reimplante. Materiales y Métodos: Estudio retrospectivo de 96 casos con infección periprotésica crónica, según los criterios de la MusculoSkeletal Infection Society, sometidos a los dos tiempos quirúrgicos en nuestra institución, entre 2008 y 2013. El seguimiento promedio fue 90 meses. La falla séptica se definió sobre la base de un consenso tipo Delphi modificado. La supervivencia sin falla séptica se definió sobre la base del estimador de Kaplan-Meier. Se compararon los resultados de supervivencia en función del cultivo intraoperatorio y de los estudios de anatomía patológica por congelación mediante la prueba del orden logarítmico. Resultados: La supervivencia sin falla séptica fue del 82,65% a los 2 años (IC95% 73,25-88,99%), 80,40% a los 5 años (IC95% 70,70-87,17%) y 77,32% a 6-10 años (IC95% 66,90-84,33%). Hubo significativamente más fallas en los pacientes con un cultivo positivo en el reimplante que en aquellos con un cultivo negativo (prueba del orden logarítmico, p = 0,0208), y en quienes tuvieron un estudio anatomopatológico por congelación positivo en el reimplante que en aquellos con un resultado negativo (prueba del orden logarítmico, p = 0,0154). Conclusiones: Los reimplantes sin recurrencias infecciosas por, al menos, 6 años tuvieron un riesgo de falla séptica muy bajo. Cuando se detectó un cultivo o una congelación positivos, la falla séptica fue significativamente mayor.

Aims Current guidelines consider analyses of joint aspirates, including leucocyte cell count (LC) and polymorphonuclear percentage (PMN%) as a diagnostic mainstay of periprosthetic joint infection (PJI). It is unclear if these parameters are subject to a certain degree of variability over time. Therefore, the aim of this study was to evaluate the variation of LC and PMN% in patients with aseptic revision total knee arthroplasty (TKA). Methods We conducted a prospective, double-centre study of 40 patients with 40 knee joints. Patients underwent joint aspiration at two different time points with a maximum period of 120 days in between these interventions and without any events such as other joint aspirations or surgeries. The main indications for TKA revision surgery were aseptic implant loosening (n = 24) and joint instability (n = 11). Results Overall, 80 synovial fluid samples of 40 patients were analyzed. The average time period between the joint aspirations was 50 days (SD 32). There was a significantly higher percentage change in LC when compared to PMN% (44.1% (SD 28.6%) vs 27.3% (SD 23.7%); p = 0.003). When applying standard definition criteria, LC counts were found to skip back and forth between the two time points with exceeding the thresholds in up to 20% of cases, which was significantly more compared to PMN% for the European Bone and Joint Infection Society (EBJIS) criteria (p = 0.001), as well as for Musculoskeletal Infection Society (MSIS) (p = 0.029). Conclusion LC and PMN% are subject to considerable variation. According to its higher interindividual variance, LC evaluation might contribute to false-positive or false-negative results in PJI assessment. Single LC testing prior to TKA revision surgery seems to be insufficient to exclude PJI. On the basis of the obtained results, PMN% analyses overrule LC measurements with regard to a conclusive diagnostic algorithm. Cite this article: Bone Jt Open 2021;2(8):566–572.

The Society of Skeletal Radiology (SSR) Practice Guidelines and Technical Standards Committee identified musculoskeletal infection as a White Paper topic, and selected a Committee, tasked with developing a consensus on nomenclature for MRI of musculoskeletal infection outside the spine. The objective of the White Paper was to critically assess the literature and propose standardized terminology for imaging findings of infection on MRI, in order to improve both communication with clinical colleagues and patient care.A definition was proposed for each term; debate followed, and the committee reached consensus. Potential controversies were raised, with formulated recommendations. The committee arrived at consensus definitions for cellulitis, soft tissue abscess, and necrotizing infection, while discouraging the nonspecific term phlegmon. For bone infection, the term osteitis is not useful; the panel recommends using terms that describe the likelihood of osteomyelitis in cases where definitive signal changes are lacking. The work was presented virtually to SSR members, who had the opportunity for review and modification prior to submission for publication.

Background Periprosthetic shoulder infection remains a difficult complication to identify and treat. In efforts to improve provide clarity, a subgroup of the Second International Consensus Meeting on Musculoskeletal Infection (ICM) generated over 70 recommendations. To understand the current treatment practices and impact of the ICM's work, a survey of shoulder arthroplasty providers was performed. Methods A 22-question survey, consisting of questions based upon the ICM consensus statement and the clinical experience of these authors, was distributed to all active members of the American Shoulder and Elbow Surgeons. Questions regarded the work-up, diagnosis, and treatment of periprosthetic shoulder infection—with specific attention to Cutibacterium acnes. Results One hundred fifty-nine members completed the survey (16%; 159/990) between August 8 and October 18, 2019. Only two-thirds of respondents reported utilizing the definition of periprosthetic shoulder infection proposed by the ICM subgroup. The survey results and associated literature review provided here demonstrate continued discordance regarding the diagnostic work-up and treatment of periprosthetic shoulder infection. Conclusion It is imperative that the shoulder arthroplasty community adopts a uniform definition for periprosthetic shoulder infection as well as a multispecialty team-based approach to improve patient care and better focus future research. Level of Evidence Level IV; Survey Study; Case Series

الملخص: أهداف البحث: على الرغم من توافر مجموعة واسعة من المضادات الحيوية، لا يتم الشفاء من العدوى العضلية الهيكلية بنجاح. إن إزالة الأوشظة، والأنسجة النخرية المصابة والغرسات ضرورية. وقد أجريت هذه الدراسة لتقييم فعالية خرز البولي ميثيل ميثكريلات، ولتحديد المتغيرات التي تؤثر على علاج وتكرار الالتهابات العضلية الهيكلية. طرق البحث: ضمت هذه الدراسة ٨٢ مريضا يعانون من التهاب العظم والنقي المزمن، الذين عولجوا على مدى ست سنوات في مستشفى الرعاية الثالثة. تابعنا ٧١ مريضا لمدة عام. وتم تقييم البيانات السريرية الدوائية لمكافحة العدوى وشفاء العظام في زيارة المتابعة الأخيرة. تم تقييم العلاقة بين حساسية المضادات الحيوية والمقاومة وتكرار العدوى لتركيبات جينتامايسين+ سيفروكسيم، وجينتامايسين+ فانكومايسين. النتائج: كان لدى ٥٣ (٦٥.٤٪) من المرضى طريق خارجي للعدوى، بينما قَدِم ٥٦(٦٨.٥١٪) من المرضى مع إفرازات جيبية وقت المراجعة. تم التحقق عند ٤٢ (٥٩٪) من المرضى من التشخيص مع مزرعة بكتيريا إيجابية. بالإضافة إلى ذلك، استخدمنا خرزات المضادات الحيوية من الجينتامايسين +السيفوروكسيم في ٧٤ (٩٠٪) من المرضى، في حين أن في ٨ (١٠٪) من المرضى استخدمنا الجنتامايسين + الفانكومايسين على أساس المزرعة ونتائج الحساسية. وتم العثور على عودة العدوى عند خمس حالات من الجنتامايسين +السيفوروكسيم واثنين من حالات الجنتامايسين + الفانكومايسين. الاستنتاجات: المضادات الحيوية التي تحتوي على خرز البولي ميثيل ميثكريلات فاعلة في علاج التهاب العظم والنقي المزمن وفي منع تكرار العدوى. ومن الضروري تحديد العوامل المختلفة المسؤولة عن تكرار الإصابة. وهذا قد يساعد الأطباء في التنبؤ بتكهن المرض وتقليل خطر النتائج السلبية. Abstract: Objective: Despite the availability of an extensive array of antibiotics, musculoskeletal infections are not cured successfully. It is necessary to remove sequestra, infected necrotic tissue, and implants. This study was undertaken to assess the efficacy of poly methyl methacrylate (PMMA) beads and identify the variables that influence eradication and recurrence in the treatment of musculoskeletal infections. Methods: This study was conducted on 82 patients with chronic osteomyelitis who were treated over a period of 6 years at our tertiary care hospital. We followed up with 71 patients for one year. Clinicoradiological data for the control of infection and bone healing were assessed at the final follow up visit. The correlation between antibiotic sensitivity/resistance and infection was evaluated for Gentamicin + Cefuroxime and Gentamicin + Vancomycin combinations. Chi-squared testing, using SPSS version 16.0, was used for statistical analysis, and a p-value < 0.05 was considered significant. Results: Fifty-three patients (65.4%) had an exogenous route of infection. Fifty-six patients (68.51%) presented with a discharging sinus on first presentation. In 42 patients (59%), the diagnosis was verified with a positive bacterial culture. In addition, we used antibiotic beads of Gentamicin + Cefuroxime in 74 patients (90%), while in 8 patients (10%), we used Gentamicin + Vancomycin, based on culture and sensitivity results. Recurrence was found in five cases of Gentamicin + Cefuroxime and two cases of Gentamicin + Vancomycin (p = 0.065). Conclusion: Antibiotics containing PMMA beads are effective in the treatment of chronic osteomyelitis and in preventing the recurrence of infection. It is imperative to identify various factors responsible for the recurrence of infection. This may help clinicians predict the prognosis of the disease and minimise the risk of adverse outcomes.

AimsHigh-energy injuries can result in multiple complications, the most prevalent being infection. Vancomycin powder has been used with increasing frequency in orthopaedic trauma given its success in reducing infection following spine surgery. Additionally, large, traumatic injuries require wound coverage and management by dressings such as negative pressure wound therapy (NPWT). NPWT has been shown to decrease the ability of antibiotic cement beads to reduce infection, but its effect on antibiotic powder is not known. The goal of this study was to determine if NPWT reduces the efficacy of topically applied antibiotic powder.MethodsComplex musculoskeletal wounds were created in goats and inoculated with a strain of Staphylococcus aureus modified to emit light. Six hours after contaminating the wounds, imaging, irrigation, and debridement and treatment application were performed. Animals received either vancomycin powder with a wound pouch dressing or vancomycin powder with NPWT.ResultsThere were no differences in eradication of bacteria when vancomycin powder was used in combination with NPWT (4.5% of baseline) compared to vancomycin powder with a wound pouch dressing (1.7% of baseline) (p = 0.986), even though approximately 50% of the vancomycin was recovered in the NPWT exudate canister.ConclusionThe antimicrobial efficacy of the vancomycin powder was not diminished by the application of NPWT. These topical and locally applied therapies are potentially effective tools that can provide quick, simple treatments to prevent infection while providing coverage. By reducing the occurrence of infection, the recovery is shortened, leading to an overall improvement in quality of life. Cite this article: Bone Joint Res 2021;10(2):149–155.

Background Periprosthetic joint infection (PJI) data elements are contained in both structured and unstructured documents in electronic health records and require manual data collection. The goal of this study is to develop a natural language processing (NLP) algorithm to replicate manual chart review for PJI data elements. Methods PJI was identified among all total joint arthroplasty (TJA) procedures performed at a single academic institution between 2000 and 2017. Data elements that comprise the Musculoskeletal Infection Society (MSIS) criteria were manually extracted and used as the gold standard for validation. A training sample of 1208 TJA surgeries (170 PJI cases) was randomly selected to develop the prototype NLP algorithms and an additional 1179 surgeries (150 PJI cases) were randomly selected as the test sample. The algorithms were applied to all consultation notes, operative notes, pathology reports, and microbiology reports to predict the correct status of PJI based on MSIS criteria. Results The algorithm, which identified patients with PJI based on MSIS criteria, achieved an f1-score (harmonic mean of precision and recall) of 0.911. Algorithm performance in extracting the presence of sinus tract, purulence, pathologic documentation of inflammation, and growth of cultured organisms from the involved TJA achieved f1-scores that ranged from 0.771 to 0.982, sensitivity that ranged from 0.730 to 1.000, and specificity that ranged from 0.947 to 1.000. Conclusion NLP-enabled algorithms have the potential to automate data collection for PJI diagnostic elements, which could directly improve patient care and augment cohort surveillance and research efforts. Further validation is needed in other hospital settings. Level of Evidence Level III, Diagnostic.

Musculoskeletal radiology is an important tool for the diagnosis of muscle damage, bone fractures, bone tumors, musculoskeletal infection, and other diseases. However, all currently used radiological techniques, including radiography, ultrasonography, computed tomography, and magnetic resonance imaging are associated with their own challenges. With its ability to address these challenges, artificial intelligence (AI) holds the promise to transform a musculoskeletal radiologist’s job in several areas. In the past, AI-based approaches in musculoskeletal radiology were primarily used for measuring bone mineral density or identifying bone tumors. However, recent studies have expanded the application of AI in several other areas, such as image segmentation, resolution enhancement, and fracture identification as well automatic diagnosis of other forms of musculoskeletal damage. This review article discusses numerous older as well as more recent studies to highlight how the development and application of AI-based approaches have evolved in the field of musculoskeletal radiology and how the applicability of these approaches may be improved in the future.

Paediatric septic arthritis, osteomyelitis and pyomyositis are infrequent diagnoses in general orthopaedic practice. However, when they present they require early diagnosis and expeditious treatment to prevent sepsis and long-term morbidity. This is challenging as the early stages of each disease can closely mimic more common and often less significant pathologies. Here we aim to address the diagnostic challenges encountered in paediatric acute musculoskeletal infection and identify when urgent surgical intervention is required. In particular we cover which key symptoms and signs should be identified in the initial clinical assessment and how blood tests and imaging can help guide diagnosis, including the use of clinical predictive algorithms. We also discuss theories regarding disease pathogenesis and how different causative organisms can lead to a wide variety of clinical presentations. Finally we present up-to-date clinical evidence regarding treatment, whether this be via surgery or antibiotics alone.

Background: Currently, one of the most pressing problems in the field of orthopedic surgery is peri-prosthetic joint infection [PJI]. While there are numerous ways to detect PJI, current clinical detection methods differ across institutions and have varying criteria and protocols. Some of these methods include the Modified Musculoskeletal Infection Society system, culturing, polymerase chain reaction, the determination of the presence of certain biomarkers, testing for the presence of alpha defensin peptides, and leukocyte level testing. Methods: This review summarizes the most recent publications in the field of PJI detection to highlight current strengths as well as provide future directions to find the system for the quickest, cost-effective, and most accurate way to diagnose these types of infections. Results: The results of this literature review suggest that, while each method of diagnosis has its advantages, each has various drawbacks as well. Current methods can be expensive, take days to weeks to complete, be prone to contamination, and can produce ambiguous results. Conclusions: The findings in this review emphasize the need for a more comprehensive and accurate system for diagnosing PJI. In addition, the specific comparison of advantages and drawbacks can be useful for researchers and clinicians with goals of creating new diagnostic tests for PJIs, as well as in clinical scenarios to determine the correct treatment for patients.

Methods of diagnosing and monitoring pediatric musculoskeletal infections are rapidly evolving. Key serologic tests are typically used in screening patients with suspected infections, and remain an integral part of the initial work-up. Synovial studies from arthrocentesis in possible septic arthritis, and source-specific cultures have been the foundation of our treatment algorithm. Given the prevalence of soft tissue abscesses and osteoarticular infections, advanced imaging is an advantageous tool. More affordable use and expanded access to MRI has made it a valuable adjunct to clinical picture and existing tests in order to comprehensively visualize the extent of musculoskeletal infections in children. Ongoing validation for criteria to help determine the patients that stand to benefit the most from MRI, even when surgical intervention may be delayed, remains of significant clinical interest. Given the rates of culture-negative infections, and the need for timely diagnosis, new diagnostic techniques are always being considered. The search for more accurate biomarkers, and technology such as Whole genome sequencing (WGS) and next-generation sequencing (NGS) that can rapidly identify pathogens of all types of phyla based on a small sample of DNA, has promising clinical implications. While once novel and prohibitively expensive, these tests are now being applied in university and tertiary care centers in certain scenarios. Applying these techniques to pediatric musculoskeletal will require a large change in lab workflow and training. However, the benefits of acquiring diagnostic information along with will make them a superior tool in our arsenal of diagnostic tests.

Background Nontuberculous mycobacterial (NTM) flexor tenosynovitis represents a rare but potentially devastating manifestation of upper extremity infection. We present a novel case of NTM flexor tenosynovitis in which Mycobacter iumimmunogenum was found to be the causative agent. Case Description The patient presented with pain and insidiously progressive swelling and required multiple operative interventions and a complex antimicrobial regimen based on susceptibility profiles. Specifically, our patient was managed with three debridements and empiric antimicrobial agents based on inherent macrolide sensitivity, with later conversion to a complex antimicrobial regimen tailored to sensitivity. Literature Review The diagnosis and management of NTM tenosynovitis arechallenging because of low suspicion, nonspecific presentation, and cumbersome laboratory identification techniques. M. immunogenum was only characterized in the past two decades, and, to our knowledge, this is the first reported case of the pathogen causing a musculoskeletal infection. Clinical Relevance We present this case primarily because of the novelty of the organism and to demonstrate the recalcitrant nature of the infection. Due to the extensive resistant patterns of M. immunogenum, management requires complex antimicrobial preparations and almost certainly needs multispecialty collaboration between orthopaedic surgery and infectious diseases.

PURPOSE OF REVIEW: Periprosthetic infection is a relatively rare but potentially devastating complication after shoulder arthroplasty. The purpose of this article is to review the incidence, diagnosis, prevention, and management of periprosthetic infections after reverse shoulder arthroplasty, with a focus on literature published within the last 5 years. RECENT FINDINGS: The 2018 International Consensus Meeting on Musculoskeletal Infection provides us with a framework for the diagnosis and management of periprosthetic infections after shoulder arthroplasty. Reverse shoulder arthroplasty has a higher reported rate of infection compared with anatomic total shoulder arthroplasty. Our current diagnostic tests do not appear to be as sensitive when compared with the hip and knee literature. Similar success has been reported with single and two-stage revision protocols, although prospective comparative data are lacking. The significance of unexpected positive cultures during revision arthroplasty remains unclear. SUMMARY: We report current diagnostic and therapeutic options for periprosthetic infection after reverse shoulder arthroplasty. Much of the current literature does not distinguish between anatomic and reverse shoulder arthroplasty. Further high-level studies are warranted to refine these definitions and guide management.

Recently, a revised definition of the minor criteria scoring system for diagnosing periprosthetic joint infection (PJI) was developed by the second International Consensus Meeting on musculoskeletal infection. The new system combines preoperative and intraoperative findings, reportedly achieving high sensitivity and specificity. We aimed to validate the modified scoring system at a high-volume center.We retrospectively reviewed patients who underwent a revision total hip or knee arthroplasty at our institution from May 2015 to August 2018. Serum C-reactive protein, synovial white blood cell count and polymorphonuclear percentage, leukocyte esterase test, alpha-defensin, microbiological and histologic results, and documented existence of sinus tract and intraoperative purulence were available for all patients. Cases with at least 1 major criterion were considered as infected. Using the new minor criteria, a score of ≥6 reflects PJI, while a score3 can be considered as noninfected. Sensitivity, specificity, mean accuracy (ACC), positive predictive value (PPV), and negative predictive value (NPV) were analyzed.A total of 345 cases were included. A cutoff score of ≥6 points had the following diagnostic performance: area under the curve (AUC) = 0.90; ACC = 0.88; sensitivity = 0.96; specificity = 0.84; PPV = 0.70; NPV = 0.98. Diagnostic performance was better for the hip (AUC = 0.92; ACC = 0.90; sensitivity = 0.96; specificity = 0.86; PPV = 0.81; NPV = 0.98) than the knee (AUC = 0.89; ACC = 0.85; sensitivity = 0.95; specificity = 0.83; PPV = 0.59; NPV = 0.98).The modified scoring system proposed by the 2018 International Consensus Meeting in diagnosing PJI showed high sensitivity and a good performance, especially as rule-out diagnostic criteria. The cutoff level seems to be different between the hip and knee. Further validation studies considering the acknowledged limitations are recommended.

Introduction: We aim to evaluate the use of silver (PorAg®) coated compared to uncoated prosthesis in two-stage revision for prosthetic joint infection (PJI) of distal femur and proximal tibia megaprosthesis in oncological patients. Materials and methods: In total, 68 patients were retrospectively evaluated. Median age was 30years (range 14–83). In total, 29 patients were re-implanted with PorAg® prosthesis and 39 with uncoated prosthesis (Megasystem C®, Waldemar Link GmbH & Co. KG, Hamburg, Germany). All patients had PJI confirmed according to Musculoskeletal Infection Society (MSIS) criteria. In 10 cases, no microorganism was identified at the time of first-stage revision, but all had a sinus communicating with the prosthesis. Successful eradication of the infection was defined by the absence of clinical/serologic evidence of infection at 6months after the second stage or at latest follow-up. Infection was again defined according to the MSIS criteria. Results: At 3-year follow-up, estimated reinfection rate in the silver group was slightly lower than in uncoated EPR (10.3% vs. 17.5%, p = 0.104). Among reinfected patients, only one out of three patients (33%) in the silver group required an amputation compared to 80% in the nonsilver group (p = 0.047). Conclusions: Our results show the efficacy of PorAg® coating in the two-stage revision of knee EPR. PorAg®-coated EPR may have possible advantages over this traditional strategy, in particular when applied to patients with a higher risk of reinfection.

Introduction: Two-stage revision is the most frequently performed revision procedure of a (suspected) periprosthetic joint infection (PJI) after total knee arthroplasty (TKA). The reported results of this treatment show large variability between studies, ranging between 0 - 40 percent failure. The purposes of this study were to determine long term (1) reinfection rate, (2) re-revision rates for any reason, and (3) the reinfection rate of patients with positive cultures at reimplantation.Methods: We prospectively followed and retrospectively reviewed 113 consecutive two-stage revision TKAs, performed between 2003 and 2013 in our clinic with a minimum follow-up of 2 years. Diagnosis of PJI was based on the major Musculoskeletal Infection Society criteria for PJI.Results: After a mean follow-up of 94 months (range 24-172 months), infection recurred in 23 cases (23%). Of these, nine cases (9%) were defined as relapse (same micro-organism as index revision) and in 14 cases another causative was found (14%). In 11 patients debridement, antibiotics and retention of the prosthesis successfully eradicated the reinfection. After overall follow-up 17 patients (17%) underwent re-revision surgery, 11 patients (11%) due to an infection and 6 patients (6%) for aseptic reasons.Conclusions: Treatment of a (suspected) infection of a TKA by a two-stage revision had acceptable results based on re-revision and re-infection rates in the long term (>5 years), resembling the short-term results (

Implementation of strategies for prevention of surgical site infection and periprosthetic joint infection is gaining further attention. We provide an overview of the pertinent evidence-based guidelines for infection prevention from the World Health Organization, the Centers for Disease Control and Prevention, and the second International Consensus Meeting on Musculoskeletal Infection. Future work is needed to ascertain clinical efficacy, optimal combinations, and the cost-effectiveness of certain measures.

Musculoskeletal infections are highly feared, form a major burden on healthcare, and may lead to severe morbidity and mortality. The diagnosis may be difficult with non-specific symptoms requiring multiple diagnostic investigations. FDG-PET/CT is one of them showing good diagnostic accuracy in most musculoskeletal infections. However, one has to be aware of the non-specific FDG uptake in patients with metallic implants and in the postsurgical phase. In this chapter, the advantages and disadvantages of the use of FDG-PET/CT in musculoskeletal infections in described for several indications: infections in the peripheral bone, spine infections/spondylodiscitis, prosthetic joint infections, diabetic foot infections, and sternal bone/wound infections. Recent published guidelines and diagnostic flowcharts by delegates of the European Association of Nuclear Medicine in collaboration with delegates from other (clinical) societies, will be discussed. At the end of this chapter, recent developments in tracer and camera systems will be presented.

Kingella kingae, a pathogen often responsible for musculoskeletal infections in children is the most common cause of septic arthritis and osteomyelitis in children 6 to 36 months of age. The aim of this study was to perform a systematic review of previous studies to determine the proportion of K. kingae in bacteriologically proven musculoskeletal infections among the pediatric population. A secondary objective was to describe the diagnostic strategies and outcome of patients with musculoskeletal infections caused by K. kingae. A systematic review was conducted to identify publications that report on musculoskeletal infections caused by K. kingae in the pediatric population (patients 0 to

Background Red flags are signs and symptoms that are possible indicators of serious spinal pathology. There is limited evidence or guidance on how red flags should be used in practice. Due to the lack of robust evidence for many red flags their use has been questioned. The aim was to conduct a systematic review specifically reporting on studies that evaluated the diagnostic accuracy of red flags for Spinal Infection in patients with low back pain. Methods Searches were carried out to identify the literature from inception to March 2019. The databases searched were Medline, CINHAL Plus, Web of Science, Embase, Cochrane, Pedro, OpenGrey and Grey Literature Report. Two reviewers screened article texts, one reviewer extracted data and details of each study, a second reviewer independently checked a random sample of the data extracted. Results Forty papers met the eligibility criteria. A total of 2224 cases of spinal infection were identified, of which 1385 (62%) were men and 773 (38%) were women mean age of 55 (± 8) years. In total there were 46 items, 23 determinants and 23 clinical features. Spinal pain (72%) and fever (55%) were the most common clinical features, Diabetes (18%) and IV drug use (9%) were the most occurring determinants. MRI was the most used radiological test and Staphylococcus aureus (27%), Mycobacterium tuberculosis (12%) were the most common microorganisms detected in cases. Conclusion The current evidence surrounding red flags for spinal infection remains small, it was not possible to assess the diagnostic accuracy of red flags for spinal infection, as such, a descriptive review reporting the characteristics of those presenting with spinal infection was carried out. In our review, spinal infection was common in those who had conditions associated with immunosuppression. Additionally, the most frequently reported clinical feature was the classic triad of spinal pain, fever and neurological dysfunction.

Inflammatory and infectious osteoarticular diseases can cause serious consequences for the patient if they are not diagnosed on time. In the last decades, different modalities of nuclear medicine have allowed to study the physiopathology of these processes, and nowadays, they play an important role in diagnosis, characterization and monitoring of musculoskeletal infectious diseases. Therefore, it is essential that every nuclear medicine physician have a vision of the advantages and disadvantages of each method and know how to use them correctly in the diagnosis of the patient. This article highlights the role of nuclear medicine in standardizing the diagnostic approach in patients with infectious/inflammatory diseases, in particular in peripheral osteomyelitis, septic arthritis, prosthetic joint infections, infected diabetic foot and spinal infections. The authors reveal the role of the most common radionuclides tests, with their advantages and clinical indications, to achieve an adequate diagnosis of infection and inflammation.

The Unyvero molecular assay was tested for the clinical resolution of discordant results, evaluating its role in prosthetic joint infection diagnosis. Objectives: The Unyvero molecular assay was tested for the clinical resolution of discordant results, evaluating its role in prosthetic joint infection diagnosis. Methods: Multiplex PCR was performed on 45 samples from prosthesis treatment (either sonication or dithiothreitol). Analytical performance was compared to that of biofilm culture using Musculoskeletal Infection Society criteria as gold standard. Results: Unyvero and biofilm culture showed similar agreement rates compared to the gold standard (34/43 and 32/43, respectively). Both methods showed six additional identifications compatible with true infection; five positive results from biofilm culture were deemed contaminations. Conclusions: The Unyvero system showed good performances and a significantly shorter turnaround time compared to cultural methods, presenting an added value to PJI diagnosis even when performed following a composite approach.

In July of 2018, the Second International Consensus Meeting (ICM) on Musculoskeletal Infection convened in Philadelphia, PA was held to discuss issues regarding infection in orthopedic patients and to provide consensus recommendations on these issues to practicing orthopedic surgeons. During this meeting, attending delegates divided into subspecialty groups to discuss topics specifics to their respective fields, which included the spine. At the spine subspecialty group meeting, delegates discussed and voted upon the recommendations for 63 questions regarding the prevention, diagnosis, and treatment of infection in spinal surgery. Of the 63 questions, 17 focused on the use of antibiotics in spine surgery, for which this article provides the recommendations, voting results, and rationales.

Aims Prosthetic joint infection (PJI) and aseptic loosening in total hip arthroplasty (THA) can present with pain and osteolysis. The Musculoskeletal Infection Society (MSIS) has provided criteria for the diagnosis of PJI. The aim of our study was to analyze the utility of F18-fluorodeoxyglucose (FDG) positron emission tomography (PET) CT scan in the preoperative diagnosis of septic loosening in THA, based on the current MSIS definition of prosthetic joint infection. Patients and Methods A total of 130 painful unilateral cemented THAs with a mean follow-up of 5.17 years (sd 1.12) were included in this prospective study. The mean patient age was 67.5 years (sd 4.85). Preoperative evaluation with inflammatory markers, aspiration, and an F18 FDG PET scan were performed. Diagnostic utility tests were also performed, based on the MSIS criteria for PJI and three samples positive on culture alone. Results The mean erythrocyte sedimentation rate, C-reactive protein, and white cell count were 47.83 mm/hr, 25.21 mg/l, and 11.05 × 109/l, respectively. The sensitivity, specificity, accuracy, negative predictive value, and false-positive rate of FDG PET compared with MSIS criteria were 94.87%, 38.46 %, 56.38%, 94.59 %, and 60.21%, respectively. The false-positive rate of FDG PET compared with culture alone was 77.4%. Conclusion FDG PET has a definitive role in the preoperative evaluation of suspected PJI. This the first study to evaluate its utility based on MSIS criteria and compare it with microbiology results alone. However, FDG PET has a high false-positive rate. Therefore, we suggest that F18 FDG PET is useful in confirming the absence of infection, but if positive, may not be confirmatory of PJI. Cite this article: Bone Joint J 2019;101-B:910–914.

Background: This study estimated operating room surface contamination rates during aseptic vs septic total joint arthroplasty and evaluated the similarity between clinically infecting organisms and those isolated from contaminated surfaces. Methods: Patients undergoing total hip and knee revision arthroplasties were identified, and surface and tissue samples were collected. Cases were classified aseptic or septic based on Musculoskeletal Infection Society criteria for prosthetic joint infection. Positive surface cultures were compared with intraoperative tissue cultures. Positive cultures were speciated and tested for antimicrobial sensitivity. Results: Samples were collected from 31 aseptic and 18 septic cases. Patients had similar demographics and time to explantation. Surface contamination rates for septic revisions were greater than those for aseptic revisions (77% vs 13%). During septic revisions, when intraoperative tissue cultures were positive, the surgical field was contaminated in 14 of 15 cases. The kappa correlation statistic for positive surgical cultures matching the surface sample was 0.9 (95% confidence interval: 0.78-1). Conclusions: Septic revisions had a significantly higher rate of surgical field contamination than aseptic revisions. Cultures suggest that bacteria contaminating the septic revision surgical field likely originated from the infected joint. Although this observation seems obvious, it is an important piece of information when discussing best practices during a single-stage exchange revision. Further clinical studies will demonstrate the use of a preparation and reset period during a single-stage revision to remove contaminated surfaces. Keywords: Total joint revision, Contamination, Prosthetic joint infection

Purpose: The child with a painful swollen knee must be worked-up for possible septic arthritis; the classic clinical prediction algorithms for septic arthritis of the hip may not be the best models to apply to the knee.Materials and methods: This was a retrospective case-control study of 17 years of children presenting to one hospital with a chief complaint of a painful swollen knee, to evaluate the appropriateness of applying a previously described clinical practice algorithm for the hip in differentiating between the septic and aseptic causes of the painful knee effusions. The diagnoses of true septic arthritis, presumed septic arthritis, and aseptic effusion were established, based upon the cultures of synovial fluid, blood cultures, synovial cell counts, and clinical course. Using a logistic regression model, the disease status was regressed on both the demographic and clinical variables.Results: In the study, 122 patients were included: 51 with true septic arthritis, 37 with presumed septic arthritis, and 34 with aseptic knee effusion. After applying a backward elimination, age 2.0 mg/dl remained in the model, and predicted probabilities of having septic knee arthritis ranged from 15% for the lowest risk to 95% for the highest risk. Adding a knee aspiration including percent polymorphonucleocytes (%PMN) substantially improved the overall model performance, lowering the lowest risk to 11% while raising the highest risk to 96%.Conclusions: This predictive model suggests that the likelihood of pediatric septic arthritis of the knee is >90% when both “age 2.0 mg/dl” are present in a child with a painful swollen knee, though, in the absence of these factors, the risk of septic arthritis remains over 15%. Aspiration of the knee for those patients would be the best next step.

We present the case of a 19-year-old man with an open fracture of the tibia and fibula secondary to an accident with an all-terrain vehicle. He underwent operative excisional irrigation, debridement, and fixation on the day of injury. His course was complicated by nonunion of the tibia fracture. Infection is a common factor in fracture nonunion, even in patients who receive appropriate surgical and antimicrobial management. Paenibacillus turicensis, an organism adapted to survive in the environment via spore formation, was responsible for nonunion in our patient. A brief discussion of this unusual organism, fracture nonunion, and the role of infection in etiology of nonunion follows.

Juan Zhang, Xiangmin Li, Guoqing Huang, Aimin Wang, Fangjie Zhang Department of Emergency Medicine, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, People’s Republic of ChinaCorrespondence: Fangjie ZhangDepartment of Emergency Medicine, Xiangya Hospital, Central South University, No. 87 Xiangya Road, Changsha, Hunan, 410008, People’s Republic of ChinaTel +86-151 1625 6248Email zhangfj@csu.edu.cnBackground: Musculoskeletal infection (MSKI) is a common reason to seek medical care in the emergency department (ED). We aimed to determine the clinical characteristics and etiology of patients with MSKI in our ED, the characteristics of MSKI with sepsis, and the predictors of death in sepsis patients.Methods: The study retrospectively analyzed patients with MSKI from April 1, 2017, to March 31, 2021. The patients were divided into non-sepsis and sepsis groups. Clinical data of these patients including their basic information, laboratory results, diagnostic results, and outcomes were collected. Statistical analysis was carried out using GraphPad Prism 5.Results: In all, 106 patients (70 male, 36 female) were enrolled in this study: 43 MSKI patients with sepsis and 63 MSKI patients without sepsis. Five patients with sepsis died. The patients’ age and sex ratio were no significantly different between the sepsis and non-sepsis groups. In the sepsis group, the ratio of rheumatic diseases, diabetes, coronary heart disease, and deep vein thrombosis was significantly different than that in the non-sepsis group (all p< 0.05). Fifty-six patients (54.37%) had positive etiology results. Staphylococcus, streptococcus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli were the most common bacteria found in both groups, but sepsis patients had more Candida albicans infections than non-sepsis patients (p=0.0331, p< 0.05). The five patients who died in the sepsis group had higher serum levels of creatinine and procalcitonin (PCT). Multivariate logistic regression analyses showed that PCT (p=0.026; odds ratio, 1.038) was significantly related to mortality.Conclusion: In MSKI patients, rheumatic diseases, diabetes, coronary heart disease, and deep vein thrombosis are the risk factors for sepsis. Staphylococcus, streptococcus, K. pneumoniae, P. aeruginosa, and E. coli were the most common bacteria in MSKI patients, while MSKI patients with sepsis had more C. albicans infections. Elevated PCT was significantly related to death in sepsis patients.Keywords: musculoskeletal infection, sepsis, emergency department, procalcitonin

Infants and children often present with a wide range of musculoskeletal (MSK) infections in daily clinical practice. This can vary from relatively benign superficial infections such as cellulitis to destructive osseous and articular infections and life-threatening deep soft tissue processes such as necrotizing fasciitis. Imaging evaluation plays an essential role for initial detection and follow-up evaluation of pediatric MSK infections. Therefore, a clear and up-to-date knowledge of imaging manifestations in MSK infections in infants and children is imperative for timely and accurate diagnosis that, in turn, can result in optimal patient management. This article reviews an up-to-date practical imaging techniques, the differences between pediatric and adult MSK infections, the spectrum of pediatric MSK infections, and mimics of pediatric MSK infections encountered in daily clinical practice by radiologists and clinicians.

With the evolution of technology and radiotracers, PET-CT has become an important imaging modality to evaluate the infection and inflammatory process. FDG is the most commonly used radiotracer; however, newer radiotracers are also under preclinical research.

Purpose The methods used for the processing of periprosthetic tissues and explanted implants to improve culture outcome especially in biofilm mediated prosthetic joint infections (PJIs) are still debated upon. Studies have reported that Dithiothreitol (DTT) pretreatment of infected devices gives similar results as sonication. However, none of them evaluated the DTT treatment of periprosthetic tissues and explanted implants in the same cohort. We evaluated the diagnostic utility of DTT treatment of periprosthetic tissue and explanted implants, as compared to the normal saline treatment of periprosthetic tissues and sonication of explanted implants for the diagnosis of PJI. Methods Seventy-three revision arthroplasty cases were prospectively included in this study. Three to five tissue specimens and the explanted implants were collected from each patient. Periprosthetic tissue samples were processed by both normal saline and DTT treatments. Explanted implants were subjected to both DTT treatment and sonication. Musculoskeletal Infection Society (MSIS) PJI criteria was used as the reference standard for the diagnosis of PJI. Results Of the 73 cases enrolled, 34 had PJI and 39 were aseptic failures. The sensitivity of DTT treated periprosthetic tissue culture (PTC) and saline treated PTC was similar (66.6% vs 58.8%, P = 0.25). The specificity of both was 100%. Sonication and DTT treatment of explanted implants showed comparable sensitivity (85.3% vs 82.4%) and specificity (100% vs 97.4%), P > 0.99. Compared to DTT treated PTC, culture of DTT treated explanted implants significantly improved the diagnosis of PJI (P = 0.03). Conclusions We could verify that DTT can be used to improve culture outcome in laboratories where biofilm detaching sonication techniques are not available for infected implants. In addition, we showed that it is possible to use DTT for treating tissue biopsies, but larger studies are required to confirm our findings.

Septic arthritis remains an orthopaedic emergency that requires prompt diagnosis and management. During the 2020 COVID-19 pandemic, British Orthopaedic Association (BOAST) guidelines dictated that medical treatment (closed-needle aspiration + antibiotic therapy) should be offered to patients as first-line management, and operative treatment (arthroscopic joint washout +/- synovectomy) be reserved for patients exhibiting signs of sepsis. Literature has previously shown that for native joint septic arthritis, operative treatment is not superior to medical treatment. During the COVID-19 ‘lock-down’ period (March 2020 to June 2020), we prospectively followed the presentation, diagnosis, management and outcome of a total of six patients who presented with confirmed native joint septic arthritis. All six patients underwent initial medical management of their septic arthritis following their diagnostic aspiration, which involved serial closed-needle aspirations and antibiotic therapy as advised by our microbiology team. Four patients went on to have an arthroscopic washout at an average of eight days following admission (mean 2.5), prior to a consultant-led decision to proceed to arthroscopic washout. The decision for operative management was the patient’s clinical deterioration based on physiological (fever, tachycardia) and biochemical (C-reactive protein (CRP), white blood cell (WBC)) parameters. All of the four patients that proceeded to operative treatment failed to provide culture yield at the time of arthroscopic washout. The mean time to discharge was 15.6 days, whilst the mean time to discharge following operative intervention was 12 days. One patient passed away during admission and one patient required a second arthroscopic washout. Medical management of septic arthritis may play a role in symptom control in the palliative setting or in patients where a general anaesthetic is undesirable. We found operative management to be therapeutic clinically, haemodynamically and biochemically as well as facilitative of a faster recovery and shorter inpatient stay.

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

Introduction: Bacillus species are often considered as contaminants when cultured from clinical samples. Bacillus cereus may be a pathogen in certain circumstances and is known to cause musculoskeletal infections. This report aims to educate clinicians and clinical microbiology laboratories on B. cereus musculoskeletal infections and to heighten awareness that Bacillus species should not always be dismissed as contaminants. Case presentation: We report the case of a patient who presented to a tertiary hospital in Pretoria, South Africa, in November 2018 with B. cereus septic arthritis and underlying systemic lupus erythematosus (SLE). The isolate would otherwise have been dismissed as a contaminant had it not been for the crucial interaction between the laboratory and the treating clinicians. To our knowledge, this is the first case report of septic arthritis caused by B. cereus in an SLE patient where the organism was cultured from the joint specimen. Identification of the organism was performed using matrix-assisted laser desorption/ionisation mass spectrometry. Management and outcome: Definitive treatment was with intravenous vancomycin, continued for four weeks, in addition to arthroscopy and management of the underlying SLE. The patient had a good clinical outcome and regained full mobility. Conclusion: Musculoskeletal infections, specifically septic arthritis caused by B. cereus, are exceedingly rare infections. Immune suppression, trauma, prosthetic implants and invasive procedures are important risk factors for B. cereus musculoskeletal infections. Close collaboration with a multi-disciplinary team approach will effect the best outcome for complicated patients with B. cereus infections.

Background Diagnosis of persistent infection at reimplantation of 2-stage exchange revision is a challenging problem. The aim of our study is to evaluate the performance of the 2018 new definition and Musculoskeletal Infection Society (MSIS) criteria in determining the persistent infection at reimplantation in patients without synovial fluid. Methods We retrospectively reviewed 150 patients who underwent 2-stage exchange revision from 2014 to 2018. Two models were used to define persistent infection—model 1: identical major criteria of the MSIS criteria and new definition and model 2: identical major criteria of 2 criteria and/or subsequent infection after reimplantation. The predictive accuracy of the new definition and MSIS criteria was compared by using receiver operating characteristic curves. Results The receiver operating characteristic curves showed that the new definition had good performance in determining the persistent infection, with the area under the curve (AUC) of 0.871 in model 1 and 0.835 in model 2. The optimal threshold for aggregate scores in new definition was 4. The MSIS criteria had limited diagnostic value in both model 1 (AUC = 0.708) and model 2 (AUC = 0.664). In model 1, the sensitivity and specificity were 86.96% and 84.25% in new definition, and 47.83% and 93.70% in MSIS criteria in patients without synovial fluid. In model 2, the sensitivity and specificity were 78.57% and 85.25% in new definition, and 39.29% and 93.44% in MSIS criteria. Conclusion The 2018 new definition of PJI is valuable in the diagnosis of persistent infection, which can improve diagnostic accuracy compared with the MSIS criteria in patients without synovial fluid.

Objective Adequate resources are required to rapidly diagnose and treat pediatric musculoskeletal infection (MSKI). The workload MSKI consults contribute to pediatric orthopaedic services is unknown as prior epidemiologic studies are variable and negative work-ups are not included in national discharge databases. The hypothesis was tested that MSKI consults constitute a substantial volume of total consultations for pediatric orthopaedic services across the United States. Study design Eighteen institutions from the Children's ORthopaedic Trauma and Infection Consortium for Evidence-based Study (CORTICES) group retrospectively reviewed a minimum of 1 year of hospital data, reporting the total number of surgeons, total consultations, and MSKI-related consultations. Consultations were classified by the location of consultation (emergency department or inpatient). Culture positivity rate and pathogens were also reported. Results 87,449 total orthopaedic consultations and 7,814 MSKI-related consultations performed by 229 pediatric orthopaedic surgeons were reviewed. There was an average of 13 orthopaedic surgeons per site each performing an average of 154 consultations per year. On average, 9% of consultations were MSKI related and 37% of these consults yielded positive cultures. Finally, a weak inverse monotonic relationship was noted between percent culture positivity and percent of total orthopedic consults for MSKI. Conclusion At large, academic pediatric tertiary care centers, pediatric orthopaedic services consult on an average of ~3,000 'rule-out' MSKI cases annually. These patients account for nearly 1 in 10 orthopaedic consultations, of which 1 in 3 are culture positive. Considering that 2 in 3 consultations were culture negative, estimating resources required for pediatric orthopaedic consult services to work up and treat children based on culture positive administrative discharge data underestimates clinical need. Finally, ascertainment bias must be considered when comparing differences in culture rates from different institution's pediatric orthopaedics services, given the variability in when orthopaedic physicians become involved in a MSKI workup.

The use of genetic sequencing modalities in the diagnosis of periprosthetic joint infection (PJI) and the identification of organisms has gained popularity recently. Polymerase chain reaction (PCR) offers timely results for common organisms. The purpose of this study was to compare the accuracy of broad-range PCR, conventional culture, the Musculoskeletal Infection Society (MSIS) criteria, and the recently proposed criteria by Parvizi et al in the diagnosis of PJI. In this retrospective study, aspirate or tissue samples were collected in 104 revision and 86 primary arthroplasties for routine diagnostic workup for PJI and sent to the laboratory for PCR. Concordance along with statistical differences between diagnostic studies were calculated using chi-square test for categorical data. On comparison with the MSIS criteria, concordance was significantly lower for PCR at 64.7% compared with 86.3% for culture ( P P =.706) or sample collection method (tissue swab or synovial fluid) ( P =.316). Of the 87 patients who met MSIS criteria, only 20 (23.0%) PCR samples had an organism identified. In this series, PCR had little utility as a stand-alone test for the diagnosis of PJI, with a sensitivity of only 23.0% when using MSIS criteria as the gold standard. Polymerase chain reaction also appears to be significantly less accurate than culture in the diagnosis of PJI. Currently, several laboratory tests used for either criteria for PJI diagnosis should be obtained along with the overall clinical picture to help guide decision-making for PJI treatment. [ Orthopedics . 2020;43(6):333–338.]

BACKGROUND The American Academy of Orthopedic Surgeons clinical practice guideline currently recommends repeat joint aspiration when workup of periprosthetic joint infection (PJI) reveals conflicting data. This guideline is based on a single study of 31 patients published 25 years ago. We sought to determine the correlation between first and second aspirations and factors that may play a role in variability between them. METHODS Sixty patients with less than 90 days between aspirations and no intervening surgery were identified at our institution and classified by Musculoskeletal Infection Society (MSIS) criteria as infected, not infected, or not able to determine after both aspirations. Culture results from both aspirations were recorded. The rates of change and correlation in clinical diagnosis and culture results between aspirations were determined. RESULTS Repeat aspiration changed the diagnosis in 26 cases (43.3%, 95% confidence interval 31.6-55.9, kappa coefficient 0.32, P < .001), and the culture results in 25 cases (41.7%, 95% confidence interval 30.1-54.3, kappa coefficient 0.27, P < .01). Among patients initially MSIS negative, the proportion who changed to MSIS positive was greater for those with a history of prior PJI compared to those without (66.7% vs 0%, P < .05), and the first aspiration mean volume was higher for those changed to MSIS positive compared to those that remained MSIS negative (12.0 vs 3.0 mL, P < .01). Among patients initially MSIS positive, the proportion of patients who changed to MSIS negative was greater for those with a history of adverse local tissue reaction (ALTR) to metal debris compared to patients without suspicion of ALTR (100% vs 7.7%, P

Background There has been recent increased focus on the importance of modifiable risk factors that can affect the risk of potentially avoidable complications such as prosthetic joint infection (PJI). We aimed to assess the relationship between adherence to a preoperative optimization protocol at our institution and its influence on the rate of PJI after primary and revision total knee arthroplasty (TKA). Methods A single-institution, retrospective study was conducted on all elective primary and revision TKAs performed over a 2-year period. PJI was diagnosed using the 2011 Musculoskeletal Infection Society criteria. Surgical outcomes and PJI were assessed relative to adherence to preoperative optimization criteria. Compliance was set as a binary variable with any case that did not meet all criteria deemed noncompliant. Results A total of 669 TKAs met inclusion criteria, including 510 primary and 159 revision TKAs. Overall compliance was 61.3%. There were 26 PJIs (3.9%) in total. The PJI rate was 1.2% (6) among primary and 14.4% (20) among revision TKAs. The rate of PJI among cases that met the preoperative optimization criteria was 2.4% (5), and the rate among cases that did not was 6.2% (21) (P Conclusions Adherence to preoperative optimization criteria may decrease the incidence of PJI after primary and revision TKA, but further study is needed to confirm the findings of this study.

Tissues from a periprosthetic joint infection (PJI) of the knee contain a heavy neutrophil polymorph (NP) infiltrate (> 5 NPs per high-powered field [HPF] by Musculoskeletal Infection Society [MSIS] criteria). PJI of the knee can be treated by a two-stage procedure and our aim was to determine whether the MSIS histological criteria for PJI diagnosis are valid in a second-stage revision knee arthroplasty. Periprosthetic tissues from 45 second-stage revision knee cases were analyzed histologically by hematoxylin–eosin and chloroacetate esterase (CAE) staining for the identification of NPs. The number of NPs was determined semiquantitatively and results correlated with the microbiological and clinical findings. In 9 of the 45 cases, an organism was cultured in two or more samples, meeting MSIS microbiological criteria for a definite diagnosis of PJI; histologically, seven of these cases contained > 5 per NPs per HPF on average, with the remaining two cases containing 1 NP and 2 NPs per HPF. In noninfected second-stage revisions, NPs were not seen in 30 cases with 6 cases showing less than 1 NP per HPF on average. The sensitivity, specificity, accuracy, and positive and negative predictive values of MSIS histological criteria (> 5 NPs per HPF) to diagnose PJI were 78%, 100%, 96%, 100%, and 95%, respectively. MSIS histological criteria for the diagnosis of PJI are valid for most but not all infected second-stage revision knee arthroplasties. Correlation of histology with clinical, microbiology and other laboratory findings is required to establish a diagnosis of PJI in second-stage revision knee arthroplasties.

Purpose The aim of this study was to evaluate the pre-operative performance of an automated multiplex PCR (mPCR) system in patients with suspected periprosthetic joint infection (PJI). Methods Under sterile conditions, synovial fluid samples from patients with a suspected PJI were collected pre-operatively. One hundred eighty microliter of the aspirate was used for analysis in the mPCR. The remaining joint fluid was sent for microbiological analysis. PJI was diagnosed by using the Musculoskeletal Infection Society (MSIS) criteria. Total percentage agreement and Cohen’s kappa coefficient were calculated to measure overall agreement. Results Overall, 90 patients with a suspected PJI were included. Using MSIS criteria, 38 (42%) patients were classified as septic. Total percent agreement between mPCR and synovial fluid culture was 86% with a Cohen’s kappa of 0.68. The mPCR and synovial fluid culture showed sensitivities of 71% and 84%, respectively. Combined evaluation provided an even higher sensitivity of 92%. While Cutibacterium spp. were detected five times by mPCR, it could only be cultured once. A higher detection rate of CoNS by mPCR (n = 7) compared to conventional culture (n = 5) was also demonstrated. In comparison to synovial fluid culture, the mPCR missed Staphylococcus aureus five times. Conclusion With a moderate agreement between synovial fluid mPCR and culture, the mPCR system could be a useful adjunct in diagnosing a PJI pre-operatively. Due to faster availability of results and a higher detection rate of low-virulent microorganisms, it can complement conventional culture.

The diagnosis of a periprosthetic joint infection (PJI) remains a clinical challenge, as there is no uniformly accepted gold standard. In 2011, the Musculoskeletal Infection Society (MSIS) convened a work group to create a standardized definition for a PJI that could be universally adopted. Based on the MSIS criteria, the diagnosis of a PJI can be made with 1 of the 2 major criteria, or 3 of the 5 minor criteria. The purpose of this study was to determine the likelihood of having a PJI based on the number of positive minor criteria and thereby develop a prediction algorithm for differentiating between a chronic PJI and a non-PJI based on the number of positive MSIS minor criteria.We retrospectively reviewed 297 patients who presented to a tertiary care center between 2004 and 2014 with a failed total joint arthroplasty and subsequently underwent a PJI workup to exclude chronic PJI. Patients were divided into 2 groups: (1) PJI group and (2) non-PJI group. Patients who had a positive PJI workup and subsequently underwent a 2-stage revision for infection were included in the PJI group. Patients who had a negative clinical and diagnostic workup were included in the non-PJI group. One hundred eighty-two patients met the criteria for inclusion in the study, 91 in each group. Univariate and multiple logistic regression analyses were used to evaluate 21 independent variables in each of the 2 groups. A prediction algorithm for differentiating between a chronic PJI and a non-PJI based on independent multivariate variables was created.Patients who had a PJI differed significantly (P.05) from those who did not have a PJI with regard to 10 independent variables, which included all the MSIS minor criteria we evaluated. Five independent multivariate variables were identified to differentiate between the 2 groups: positive cultures, elevated synovial white blood cell count, elevated synovial polymorphonuclear neutrophil percentage, elevated erythrocyte sedimentation rate, and elevated C-reactive protein. The predictive probability of a PJI for all 32 combinations of these 5 variables was: 3.6% for 1 positive variable, 19.3% for 2, 58.7% for 3, 83.8% for 4, and 97.8% for 5. The chi-squared test for trend and the area under the receiver-operating characteristic curve (0.977) suggest that the model is highly predictive, with an excellent diagnostic performance in identifying a PJI.Diagnosing a PJI remains a clinical challenge as there is no gold standard for diagnosis. The development of the MSIS criteria, which is based on a consensus of over 400 of the world's experts in musculoskeletal infection, was a major step forward in defining the diagnosis of a PJI. However, to our knowledge, the likelihood of having a PJI based on the number of positive minor criteria has yet to be validated or quantified. Of the 20 independent variables that were evaluated, 10 were found to be significantly associated with a PJI, including all the MSIS minor criteria evaluated. In addition, a diagnostic prediction algorithm was constructed to determine the likelihood of a PJI based on 5 binary independent multivariate variables. The relationship was also examined with a receiver-operating characteristic curve analysis. The area under the curve was 0.98, indicating excellent diagnostic performance for the MSIS minor criteria in identifying a PJI.III.