[Diagnosis of periprosthetic joint infection : Development of an evidence-based algorithm by the work group of implant-associated infection of the AE-(German Society for Arthroplasty)]. / Diagnostik der periprothetischen Infektion : Entwicklung eines evidenzbasierten Algorithmus der Arbeitsgruppe implantatassoziierte Infektion der Arbeitsgemeinschaft Endoprothetik.

BACKGROUND: Prosthetic joint infections (PPI) will challenge orthopaedic surgeons and the health care system in the coming years. Evidence-based and reliable preoperative diagnostics are necessary for success in the field of revision arthroplasty. Especially the preoperative detection of PPI is important with respect to the treatment strategy. AIM: The aim of this study was to develop a detailed and structured standard operating procedure (SOP) to detect PPI preoperatively. METHODS: A systematic literature research was performed and relevant articles identified. After extracting the data, statistical calculations of sensitivity, specificity, positive/negative predictive value and positive/negative likelihood ratio were performed. The results were discussed and evaluated in four meetings analogously to standard Delphi rounds by the workgroup of implant-associated infections of the German AE (Arbeitsgemeinschaft Endoprothetik). An algorithm for the diagnostic approach according to ISO 5807 was made. RESULTS: The standardized algorithm combines a sequence of evidence-based procedures with detailed and structured main and additional criteria to every critical step in the diagnostic approach. CONCLUSION: The detection of PPI is of tremendous importance prior to revision arthroplasty and determines its success or failure. The diagnosis "prosthetic joint infection" requires a substantial change with respect to treatment concepts. The algorithm summarizes current literature and specialized expert opinions in a modern standardized format for a transparent diagnostic approach.

[Septic arthritis of the native joint and after ligamentoplasty : Diagnosis and treatment]. / Septische Arthritis des nativen Gelenkes und nach Bandplastik : Diagnostik und Behandlung.

BACKGROUND: Septic arthritis is an acute emergency. It occurs more frequently in patients with pre-existing degenerative or chronic inflammatory joint diseases than in the general population. The causative microorganisms can be introduced in various ways. DIAGNOSTICS: A rapid diagnosis is of great importance for the success of the therapy. In the clinical examination, the typical signs of inflammation are noticeable. The gold standard is the aspiration of synovial fluid and the subsequent laboratory and microbiological investigation. THERAPY: A prerequisite for successful therapy is the early initiation of an antimicrobial pathogen-specific treatment and the surgical alleviation of the joint.

Influence of retrieved hip- and knee-prosthesis biomaterials on microbial detection by sonication.

Microorganisms' ability to adhere and form a biofilm differs among biomaterials; however, clinical data are conflicting. Microbial adherence and biofilm formation on different biomaterials of explanted joint prosthesis components were investigated. Consecutive patients with explanted joint prosthesis were prospectively included. The bacterial load dislodged from retrieved prosthetic components was evaluated qualitatively and quantitatively in sonication-fluid cultures. For comparison between groups, one-way ANOVA and Wilcoxon signed-rank test were used. A total of 112 components originating from 58 knee and 54 hip prostheses were retrieved from 40 patients. Components were made of titanium alloy in 42 cases, cobalt-chromium alloy in 38 and polyethylene in 32. Bacteria in sonication-fluid cultures grew in all polyethylene components (100 %), followed by titanium alloy (79 %) and cobalt-chromium components (71 %). Larger bacterial counts were found on polyethylene than on titanium (p < 0.013) or cobalt-chromium alloy (p = 0.028). Coagulase-negative Staphylococcus aureus and Streptococcus species were most commonly isolated. In conclusion, polyethylene showed larger biofilm burden than metal alloys, indicating their higher microbial adhesion affinity in vivo. Sonication of polyethylene liners, rather than the whole prosthesis, was sufficient for diagnosis of prosthetic joint infection. Moreover, bacterial counts were larger after sonication of polyethylene liners than of metal alloys, suggesting intrinsic differences in the ability for biofilm formation on various biomaterials. Polyethylene liners allowed the diagnosis of prosthetic joint infections (PJIs) in all investigated cases, suggesting that sonication of polyethylene liners rather than of the complete prosthesis was sufficient for pathogen detection in PJIs.

[Osteosynthesis-associated infections : Epidemiology, definition and diagnosis]. / Osteosyntheseassoziierte Infektionen : Epidemiologie, Definition und Diagnostik.

Osteosynthesis-associated infections occur in 1-5% after closed and in up to 30% after open fractures. There are three different descriptions of implant-associated infections after fracture fixation, which are crucial for the selection of the adequate treatment strategy; temporal appearance from the index surgery (early versus late), pathogenesis of the infection (exogenous, hematogenous and contiguous from an adjacent focus), duration of infection symptoms (acute versus chronic). Diagnosis of osteosynthesis-associated infection is challenging, as chronic low-grade infections often present only with unspecific and subtle clinical symptoms. History, clinical evaluation, imaging, histopathlogical and microbiological examination build the cornerstones of diagnostics in implant-associated infections. A new onset of rest pain, early loosening of the prosthesis or mechanically unexplained, nonunion should raise suspicion for infection and prompt further evaluation. Percutaneous sinus tracts, purulent wound secretion and skin erosions with visibility of the implant confirm the implant-associated infection. Elevated C­reactive protein value in blood is a supportive argument for infection, but is neither sensitive nor specific for infection. Imaging plays a key role to detect nonunions, infectious callus, sequester, peri-implant osteolysis and extraosseous and intramedullary involvement. Through microbiological and histopathological examination of intraoperative tissue samples, as well as sonication of explanted implants the causative pathogen is identified in most cases.

[Management of periprosthetic infections of the knee]. / Management periprothetischer Infektionen des Kniegelenks.

Endoprosthetic replacement is one of the most successful operations in current medicine. As the implantation of knee prostheses increases, the number of periprosthetic infections is also rising. In case of painful or early loosening of the prosthesis an infection should be excluded by joint aspiration. Retention of the prosthesis with change of mobile parts is possible only in acute infections (< 4 weeks after surgery or duration of symptoms of <3 weeks in the case of hematogenous infection), if the prosthesis is stable, the soft tissue is intact, and no difficult-to-treat pathogens were found. In other cases a one- or two-stage prosthesis exchange should be performed. In a two-stage exchange, a short interval of 2-3 weeks is possible, if biofilm-active treatment is available. Rifampin should be used targeted (after isolation of the pathogen) and only in combination with another efficient antibiotic. In this article the current management concepts of periprosthetic infection of the knee are discussed.

[Sonication in the diagnosis of periprosthetic infections : Significance and practical implementation]. / Sonikation in der Diagnostik periprothetischer Infektionen : Stellenwert und praktische Umsetzung.

Endoprosthetic joint replacement is one of the most common and most successful operations in current medicine. With the increase in joint prosthesis implantations, the number of periprosthetic infections is also rising. Detection of the causative pathogen and its antimicrobial susceptibility is crucial for successful antibiotic therapy. For a reliable diagnosis, in addition to conventional microbiological methods (synovial fluid culture and intraoperative periprosthetic tissue samples), other methods of detecting biofilms are used. With sonication of the removed implant components, microorganisms are released from the implant surface and then detected qualitatively and quantitatively in the sonication fluid. The sonication is particularly useful for chronic, "low-grade" infections in which a small number of bacteria are present and the biofilm adheres more strongly to the prosthesis surface. The sonication fluid is suitable for aerobic and anaerobic cultures, in addition to newer, culture-independent detection methods (e.g., molecular methods, mass spectrometry, microcalorimetry). In the article the significance, advantages and disadvantages, and the practical implementation of the sonication of implants are presented and critically discussed.

Prevalence of comorbidities, and affective disorders in epilepsy: A latent class analysis approach.

OBJECTIVE: Epilepsies are severe chronic neurological diseases that impair several domains in life and are often accompanied by various somatic and psychiatric comorbidities. Associations between epilepsy and its comorbidities remain poorly understood. As epidemiological research mainly relies on cross-sectional designs and descriptive results, homogeneities regarding comorbidities in individuals suffering from epilepsy remain uncovered. Therefore, we aimed to identify clusters of individuals based on selected seizure-related variables and somatic comorbidities, and their respective risk of experiencing affective disorders, using a Latent Class Analysis (LCA). METHODS: Latent class analysis, is a model-driven statistical approach, which aims at latent, unobservable clusters on selected disease features. LCA has therefore the potential for uncovering previously unobservable groups or classes with similar comorbidity patterns. It allows for comparisons between those classes regarding risk or promotive factors - such as affective disorders. Our data derives from the Austrian cohort of the European Study on Burden and Care of Epilepsy (ESBACE; http://www.esbace.eu/). In ESBACE, multiple factors were collected to get a detailed picture on prevalence, epilepsy-related variables and comorbidities in a population-based cohort from the region of Salzburg, Austria. We used LCA to identify epilepsy-somatic-comorbidity-clusters and further, compared them to the observed the risk of suffering from affective disorders. RESULTS: The prevalence of epilepsy in the study region was 9.14/1000 inhabitants. LCA unveiled a three-cluster solution, of which one cluster, mainly consisting of individuals with mixed seizure types, higher age, and discrete somatic comorbidities (stroke, cardiovascular - and respiratory/pulmonary diseases) had a higher risk of experiencing affective disorders. SIGNIFICANCE: To our knowledge, this is the first large scale study that uses LCA to identify epilepsy-related comorbidity phenotypes, and therefore it might open a new way for epidemiological research.

Origin and characteristics of haematogenous periprosthetic joint infection.

OBJECTIVES: Recognition of infectious origin of haematogenous periprosthetic joint infections (PJI) is crucial. We investigated the primary focus and characteristics of haematogenous PJI. METHODS: Consecutive patients who presented with haematogenous PJI between 01/2010 and 01/2018 were retrospectively analysed. Haematogenous PJI was defined by diagnosis of infection ≥1 month after surgery, acute manifestation after a pain-free period and positive blood or prosthetic-site culture and/or evidence of distant infectious focus consistent with the pathogen. Fisher's exact, Student's t and Mann-Whitney U tests were used, as appropriate. RESULTS: A total of 106 episodes of PJI were included, involving 59 knee, 45 hip, one shoulder and one elbow prostheses. The median time from last surgery until haematogenous PJI was 47 months (range, 1-417 months). The pathogen was identified in 105 episodes (99%), including Staphylococcus aureus (n = 43), streptococci (n = 32), enterococci (n = 13), Gram-negative bacteria (n = 9) and coagulase-negative staphylococci (n = 8). Gram-negative bacteria were significantly more often found in hip joints than in knee joints. Blood cultures grew the pathogen in 43 of 70 episodes (61%). The primary infectious focus was identified in 72 episodes (68%) and included infections of intravascular devices or heart valves (22 episodes), skin and soft tissue (16 episodes), the oral cavity (12 episodes), urogenital (12 episodes) or gastrointestinal tract (seven episodes) and other sites (three episodes). CONCLUSIONS: In acute PJI manifesting after a pain-free period, the haematogenous infection route should be considered and the primary infectious focus should be actively searched for. The cardiovascular system, skin and soft tissue, oral cavity, urogenital and gastrointestinal tracts were common origins of haematogenous PJI.

A standardized interdisciplinary algorithm for the treatment of prosthetic joint infections.

AIMS: In 2013, we introduced a specialized, centralized, and interdisciplinary team in our institution that applied a standardized diagnostic and treatment algorithm for the management of prosthetic joint infections (PJIs). The hypothesis for this study was that the outcome of treatment would be improved using this approach. PATIENTS AND METHODS: In a retrospective analysis with a standard postoperative follow-up, 95 patients with a PJI of the hip and knee who were treated with a two-stage exchange between 2013 and 2017 formed the study group. A historical cohort of 86 patients treated between 2009 and 2011 not according to the standardized protocol served as a control group. The success of treatment was defined according to the Delphi criteria in a two-year follow-up. RESULTS: Patients in the study group had a significantly higher Charlson Comorbidity Index (3.9 vs 3.1; p = 0.009) and rate of previous revisions for infection (52.6% vs 36%; p = 0.025), and tended to be older (69.0 vs 66.2 years; p = 0.075) with a broader polymicrobial spectrum (47.3% vs 33.7%; p = 0.062). The rate of recurrent infection (3.1% vs 10.4%; p = 0.048) and the mean time interval between the two stages of the procedure (66.6 vs 80.7 days; p < 0.001) were reduced significantly in the study group compared with the control group. CONCLUSION: We were able to show that the outcome following the treatment of PJIs of the hip and knee is better when managed in a separate department with an interdisciplinary team using a standard algorithm.

High failure rates in treatment of streptococcal periprosthetic joint infection: results from a seven-year retrospective cohort study.

AIMS: To investigate the outcomes of treatment of streptococcal periprosthetic joint infection (PJI) involving total knee and hip arthroplasties. PATIENTS AND METHODS: Streptococcal PJI episodes which occurred between January 2009 and December 2015 were identified from clinical databases. Presentation and clinical outcomes for 30 streptococcal PJIs in 30 patients (12 hip and 18 knee arthroplasties) following treatment were evaluated from the medical notes and at review. The Kaplan-Meier survival method was used to estimate the probability of infection-free survival. The influence of the biofilm active antibiotic rifampin was also assessed. RESULTS: The infection was thought to have been acquired haematogenously in 16 patients and peri-operatively in 14. The median follow-up time for successfully treated cases was 39.2 months (12 to 75), whereas failure of the treatment occurred within the first year following treatment on every occasion. The infection-free survival at three years with 12 patients at risk was 59% (95% confidence interval 39% to 75%). Failure of the treatment was observed in ten of 22 PJIs (45%) treated with a two-stage revision arthroplasty, two of six (33%) treated by debridement and prosthesis retention, and in neither of the two PJIs treated with one-stage revision arthroplasty. Streptococcal PJI treated with or without rifampin included in the antibiotic regime showed no difference in treatment outcome (p = 0.175). CONCLUSION: The success of treatment of streptococcal PJI in our patient cohort was poor (18 of 30 cases, 59%). New therapeutic approaches for treating streptococcal PJI are needed. Cite this article: Bone Joint J 2017;99-B:653-9.

CD15 focus score: Infection diagnosis and stratification into low-virulence and high-virulence microbial pathogens in periprosthetic joint infection.

INTRODUCTION: The aim of the work was to validate the CD15 focus score for the infection pathology of periprosthetic joint infection in a large group and to clarify whether a stratification into low-virulence and high-virulence microbial pathogens is possible by means of the CD15 focus score (quantification of CD15 positive granulocytes). METHODS: The histopathology of 275 synovial tissue samples taken intraoperatively during revision operations (n=127 hip, n=141 knee, n=2 shoulder, n=5 ankle) was evaluated according to the SLIM consensus classification (SLIM=synovial-like interface membrane). Neutrophilic granulocytes (NG) were quantified by the CD15 focus score on the basis of the principle of focal maximum infiltration (focus) with evaluation of one field of vision (about 0.3mm2). The quantification values were compared with the microbiological diagnoses taking into consideration the virulence groups of low-virulence and high-virulence microbial pathogens and mixed infection. RESULTS: The patients with positive microbiological findings (n=160) had significantly (p<0.001, Mann-Whitney U test) higher CD15 focus score values than patients with negative microbiological findings (n=115), the cut-off value being 39 cells per high power field (HPF). The CD15 focus score values of low-virulence microbial pathogens (n=94) were significantly lower (p<0.001, Mann-Whitney U test) than the values of high-virulence microbial pathogens (n=55), the cut-off value being 106 cells per HPF. Based on the microbiological diagnosis the sensitivity with respect to a microbial infection is 0.91, the specificity 0.92 (PPV=0.94; NPV=0.88; accuracy: 0.92; AUC=0.95). Based on the differentiation of the CD15 focus score values between low-virulence and high-virulence microbes the sensitivity is 0.70 and the specificity 0.77 (PPV=0.63; NPV=0.81; accuracy=0.74; AUC=0.74). CONCLUSION: As a result of the high sensitivity and specificity, the easy to use CD15 focus score is a diagnostically valid score for microbial periprosthetic infection. A differentiation between low-virulence and high-virulence microorganism of sufficiently high diagnostic quality is additionally possible as a result of the defined quantification of CD15 positive granulocytes (the CD15 focus score) histopathological diagnosis of microbial infections is possible, which on the one hand supports the microbiological diagnosis and on the other hand by the stratification into low-virulence and high-virulence microbial pathogens could represent an additional basis for a pathogen-specific antibiotic treatment in the event of unclear constellations of findings.

[Implant-associated infections - Diagnostics]. / Implantatassoziierte Infektion - Diagnostik.

The diagnosis of implant-associated infections is challenging as chronic low-grade infections often only manifest as subtle clinical symptoms. Clinical evaluation, patient history, imaging, histopathological and microbiological examinations build the cornerstones of the diagnostics for implant-associated infections. New onset of pain at rest, local symptoms at the surgical site and early loosening of the prosthesis or pseudarthrosis should raise suspicion for an infection and prompt further evaluation. Percutaneous sinus tracts, purulent wound secretions and skin erosions with exposure of the implant are certain signs of implant-associated infections. Elevated C­reactive protein levels in blood support the diagnosis of infection but are neither sufficient sensitive nor specific to confirm or exclude infection. Preoperative antibiotic therapy interferes with the diagnostic evaluation and should be avoided. In periprosthetic joint infections, joint aspiration with determination of the leukocyte count and microbiological examination is a crucial first diagnostic step. Through microbiological and histopathological examinations of intraoperative tissue samples, as well as sonication of explanted implants, the causative pathogen can be identified in most cases. In osteosynthesis-associated infections imaging plays a key role to detect non-union, infection callus, sequester, peri-implant osteolysis and extraosseous and intramedullary pathologies. In prosthetic joint infections imaging provides information about the position and stability of the prosthesis. In case of hematogenic infection seeding from a distant focus, blood cultures should be sampled, followed by a meticulous investigation of potential primary focus of infection, depending on the causative agent.

[Treatment of periprosthetic infections]. / Therapie der periprothetischen Infektion.

The increasing number of prosthesis implantations and higher life expectancy lead to a growing number of periprosthetic infections (PPI). Optimal therapy necessitates interdisciplinary coordination of surgical and antimicrobial treatment. Challenges in the treatment are the increased occurrence of resistant pathogens, selection of adequate antimicrobial and surgical treatment strategies, inappropriate pretreatment and comorbidities of patients. Current treatment concepts lead to a high success rate in terms of infection eradication, when correctly applied. The individual expectations and underlying conditions of each patient must be considered when determining the therapy concept. The first step is to distinguish between acute and chronic infections. In acute infections the prosthesis can be retained but chronic infections necessitate a complete exchange of the prosthesis. Complicating factors, such as compromising soft tissue and bone conditions, osteomyelitis and infections caused by difficult-to-treat bacteria should, however, always be treated by a complete exchange of the prosthesis, even for acute infections. The antimicrobial treatment must be tailored to the causative agent, the surgical strategy as well as comorbidities and drug intolerances of the patient. It is important to distinguish between biofilm-active eradication therapy with rifampicin for gram-positive pathogens and quinolones for gram-negative organisms and suppression therapy. This article gives a structured presentation of the therapy algorithm.

[Emergency screw osteosynthesis of femoral neck fractures]. / Notfallmässige Schraubenosteosynthese von Schenkelhalsfrakturen.

27 patients with femoral neck fractures have been treated by ORIF with 3 or 4 large cancellous bone screws. The operation has been performed as an emergency intervention within 5 1/2 hours after accident. Anterior arthrotomy in direction of the long axis of the neck for evacuation of the intraarticular hematoma has been performed as a routine. Personal follow-up with X-ray documentation after 18 to 106 months (mean 29.5 months) showed complete rehabilitation in 22 patients and 2 femoral head necroses (7.4%). We conclude that these good results are due to the short interval between accident and operation as well as to the evacuation of the intraarticular hematoma, together with a stable internal fixation and functional rehabilitation.

[The dynamic hip screw (DHS) in femoral neck fractures]. / Dynamische Hüftschraube (DHS) bei Schenkelhalsfrakturen.

Out of 224 patients with femoral neck fractures, 40 patients have been treated by ORIF with the dynamic hip screw, whereas 27 have been fixed by large cancellous bone screws and 148 femoral heads were replaced by a prosthesis. The ORIF with dynamic hip screw has been performed as an emergency intervention within 6.2 hours after accident. Good general condition without contraindication against an emergency operation as well as a biological age below 65 years and no pre-existing coxarthrosis are mandatory for the indication for open rigid internal fixation. Personal follow-up of 37 patients with x-ray documentation after at least 18 months (mean 35.4 months) showed complete rehabilitation in 31 patients and 4 femoral head necrosis (10.8%). We conclude that these good results are due to the short interval between accident and operation as well as to the evacuation of the intraarticular hematoma together with stable internal fixation and functional rehabilitation. Due to our good results we prefer long cancellous bone screws for the operative fixation of femoral neck fractures in younger patients, whereas in the older group the dynamic hip screw is preferred.