Favourable outcomes of repeat one-stage exchange for periprosthetic joint infection of the hip.

AIMS: One-stage exchange for periprosthetic joint infection (PJI) in total hip arthroplasty (THA) is gaining popularity. The outcome for a repeat one-stage revision THA after a failed one-stage exchange for infection remains unknown. The aim of this study was to report the infection-free and all-cause revision-free survival of repeat one-stage exchange, and to investigate the association between the Musculoskeletal Infection Society (MSIS) staging system and further infection-related failure. METHODS: We retrospectively reviewed all repeat one-stage revision THAs performed after failed one-stage exchange THA for infection between January 2008 and December 2016. The final cohort included 32 patients. The mean follow-up after repeat one-stage exchange was 5.3 years (1.2 to 13.0). The patients with a further infection-related failure and/or all-cause revision were reported, and Kaplan-Meier survival for these endpoints determined. Patients were categorized according to the MSIS system, and its association with further infection was analyzed. RESULTS: A total of eight repeat septic revisions (25%) developed a further infection-related failure, and the five-year infection-free survival was 81% (95% confidence interval (CI) 57 to 92). Nine (28%) underwent a further all-cause revision and the five-year all-cause revision-free survival was 74% (95% CI 52 to 88). Neither the MSIS classification of the host status (p = 0.423) nor the limb status (p = 0.366) was significantly associated with further infection-related failure. CONCLUSION: Repeat one-stage exchange for PJI in THA is associated with a favourable five-year infection-free and all-cause revision-free survival. Notably, the rate of infection control is encouraging when compared with the reported rates after repeat two-stage exchange. The results can be used to counsel patients and help clinicians make informed decisions about treatment. With the available number of patients, further infection-related failure was not associated with the MSIS host or limb status. Cite this article: Bone Joint J 2022;104-B(1):27-33.

Patients with no recurrence of infection five years after two-stage revision hip arthroplasty may be classified as periprosthetic infection 'in remission'.

AIMS: We aimed to report the mid- to long-term rates of septic and aseptic failure after two-stage revision surgery for periprosthetic joint infection (PJI) following total hip arthroplasty (THA). METHODS: We retrospectively reviewed 96 cases which met the Musculoskeletal Infection Society criteria for PJI. The mean follow-up was 90 months (SD 32). Septic failure was assessed using a Delphi-based consensus definition. Any further surgery undertaken for aseptic mechanical causes was considered as aseptic failure. The cumulative incidence with competing risk analysis was used to predict the risk of septic failure. A regression model was used to evaluate factors associated with septic failure. The cumulative incidence of aseptic failure was also analyzed. RESULTS: There were 23 septic failures at final follow-up, with a cumulative incidence of 14% (95% confidence interval (CI) 8% to 22%) at one year, 18% (95% CI 11% to 27%) at two years, 22% (95% CI 14% to 31%) at five years, and 23% (95% CI 15% to 33%) at ten years. Having at least one positive culture (hazard ratio (HR) 2.38 (interquartile range (IQR) 1.19 to 4.74); p = 0.013), or a positive intraoperative frozen section (HR 2.55 (IQR 1.06 to 6.15); p = 0.037) was significantly associated with septic failure after reimplantation. With dislocation being the most common cause of aseptic revision (5.2%), the cumulative incidence of aseptic failure was 1% (95% CI 0% to 5%) at one year, 6% (95% CI 1% to 8%) at five years, and 8% (95%CI 3% to 17%) at ten years. CONCLUSION: If there is no recurrent infection in the five years following reimplantation, the chances of further infection thereafter are remote. While the results of a frozen section may be a reliable guide to the timing of reimplantation, intraoperative culture has, currently, only prognostic value. Surgeons should be aware that instability remains a potential indication for further revision surgery. Cite this article: Bone Joint J 2021;103-B(1):79-86.

Improved diagnostic accuracy with the classification tree method for diagnosing low-grade periprosthetic joint infections by quantitative measurement of synovial fluid alpha-defensin and C-reactive protein.

BACKGROUND: The diagnosis of low-grade periprosthetic joint infections (PJIs) is challenging, because patients may present with unspecific symptoms, false-negative cultures, or marginally elevated values of serum biomarkers like C-reactive protein (CRP). This may lead to the unintended implantation of a revision prosthesis into an infected surgical site with a repeat risk of short-term failure. Conversely, false diagnosis of joint infection may result in multistage revision procedures, which expose the patient to unnecessary surgical procedures and inappropriate antibiotic treatment. Here, we investigated whether synovial biomarkers can preoperatively distinguish between aseptic prosthesis loosening and low-grade joint infection and the most accurate biomarker combinations. METHODS: Inclusion criteria for the study were indication for revision arthroplasty due to aseptic implant failure, acute high-grade infection, or (suspected) low-grade infection. We prospectively collected synovial fluid of patients undergoing revision arthroplasty for quantitative measurement of alpha defensin, CRP, interleukin (IL-6), IL-10, and lipopolysaccharide binding protein (LBP). RESULTS: The classification tree method revealed alpha defensin and CRP as the most suitable biomarker combination to distinguish between aseptic loosening and low-grade joint infection. The combination of CRP > 2.0 mg/L and alpha defensin > 90.000 pg/mL correctly identified nine  of 11 patients with low-grade infection. CONCLUSIONS: Alpha defensin plus CRP seems to be the most helpful combination for pre-operative discrimination of aseptic loosening vs. low-grade joint infection.

Management of Surgical Site Infections.

The American Academy of Orthopaedic Surgeons has developed Appropriate Use Criteria for the Management of Surgical Site Infections (SSIs) (website: http://www.orthoguidelines.org/go/auc/default.cfm?auc_id=225018&actionxm=Terms). Evidence-based information, in conjunction with the clinical expertise of physicians, was used to develop the criteria to improve patient care and obtain best outcomes while considering the subtleties and distinctions necessary in making clinical decisions. The Appropriate Use Criteria for the Management of SSIs were derived by identifying clinical indications typical of patients commonly presenting with a SSI in clinical practice. These indications were most often parameters observable by the clinician, including symptoms and diagnostic tests. The 264 patient scenarios and nine treatments were developed by the writing panel, which consisted of a group of clinicians who are specialists in this Appropriate Use Criteria topic. Next, a separate, multidisciplinary, voting panel (made up of specialists and nonspecialists) rated the appropriateness of treatment of each patient scenario using a nine-point scale to designate a treatment as appropriate (median rating, seven to nine), may be appropriate (median rating, four to six), or rarely appropriate (median rating, one to three).

[Treatment of orthopedic implant-associated infections]. / Handläggning av infektioner vid ortopediska implantat en utmaning för vården.

The Swedish National Guidelines for Bone and Joint Infections were revised during 2018. The work was carried out on behalf of the Swedish Society for Infectious Diseases. The study group consists of senior consultants in infectious diseases, supported by specialists in orthopedic surgery, clinical microbiology and allergology when needed. The study group emphasizes that implant associated infections are challenging and requires multidisciplinary cooperation, including, but not limited to, specialists in orthopedic surgery, infectious diseases, clinical microbiology and radiology for optimal treatment results. All aspects of the clinical management are equally important; selecting the optimal antibiotic prophylaxis in arthroplasty as well as fracture surgery, early diagnosis of infection, adequate treatment, follow-up, and finally a structured evaluation of outcome. Profound and updated knowledge of treatment of biofilm related infection is necessary to achieve optimal results in patients with implant-associated infections. Future challenges include improved decision support for combining surgical treatment with selection of proper antibiotics, as well as management of antibiotic resistance, drug-drug interactions and adverse effects of antibiotic treatment.

What Is the Definition of Acute and Chronic Periprosthetic Joint Infection (PJI) of Total Ankle Arthroplasty (TAA)?

RECOMMENDATION: There is a paucity of data for defining acute or chronic periprosthetic joint infection (PJI) following total ankle arthroplasty (TAA) in the literature. Any discussion of PJI after ankle replacement is entirely reliant on the literature surrounding knee and hip arthroplasty. LEVEL OF EVIDENCE: Consensus. DELEGATE VOTE: Agree: 100%, Disagree: 0%, Abstain: 0% (Unanimous, Strongest Consensus).

Histological score for degrees of severity in an implant-associated infection model in mice.

INTRODUCTION: Several scores were introduced to diagnose and to classify osteomyelitis in practice. Mouse models are often used to study the pathophysiology of bone infection and to test therapeutic strategies. Aim of the present study was to design a score to diagnose and quantify implant-associated infection in a murine experimental model. MATERIALS AND METHODS: Four independent parameters were developed: existence of callus, consolidation of the fracture, structural changes of the medullary cavity and number of bacteria. The score was assessed in a standardized implant-associated mouse model with 35 BALB/c-mice. The left femur was osteotomized, fixed by a titanium locking plate and infection was induced by inoculation of Staphylococcus aureus into the fracture gap. For the sham group, the procedure was performed without inoculation of bacteria. The score was assessed on days 7, 14 and 28. Each item of the score showed lower values for the infection group compared to the controls after 4 weeks. RESULTS: Regardless of the assessed time point, the overall total score was significantly higher in the control group compared to the infection group (p < 0.0001). Analysis revealed a sensitivity of 0.85, specificity of 1.0, negative predictive value of 0.67 and positive predictive value of 1.0. CONCLUSION: The proposed score assessing severity of fracture-related infection in an implant-associated murine model was easy to access, feasible to diagnose and estimate bone healing and infection in a murine bone infection with a high sensitivity. Therefore, this score might be a useful tool to quantify infection-related changes after fracture in further future preclinical studies.

A new perspective on current prosthetic joint infection classifications: introducing topography as a key factor affecting treatment strategy.

Periprosthetic joint infection (PJI) is a relatively frequent and devastating complication following prosthetic joint implantation. Several classification systems have been presented by various authors and are routinely used in clinical practice to help in early diagnosis and treatment. The most widely accepted classifications of periprosthetic infections rely on the timing of clinical presentation. Unfortunately, these schemes possess important shortcomings which limit their usefulness in clinical practice, as data reported in literature are contrasting, with success rate ranging from 60 to 80%, irrespectively of prosthetic infection timing. An attempt is made by us to update the current knowledge on PJIs by looking them from a different perspective, introducing a topographic principle in their classification. Our approach is based on the theory that identifying the exact location of the bacterial colonization may allow to decide whether to conservatively treat the patient or to perform a more radical intervention. The aim is to improve the understanding of the aetiology of this serious complication, lead to the appropriate treatment strategy according to the stage of the disease thus enhancing the outcomes of surgical management. Such a strategy, if widely accepted, could guide research studies on the management of PJIs. The availability of investigations like scintigraphy could aid in identifying pathogenetic processes and their exact location, which may be missed on conventional radiographs, and could enable orthopaedic surgeons to have a better understanding of PJI patterns.

Species and antimicrobial susceptibility testing of coagulase-negative staphylococci in periprosthetic joint infections.

The objective was to evaluate the distribution of coagulase-negative staphylococci (CNS) involved in periprosthetic-joint infections (PJIs) and to describe their susceptibility profile to antibiotics. We conducted a multicentre retrospective study in France, including 215 CNS PJIs between 2011 and 2015. CNS PJIs involved knees in 54% of the cases, hips in 39%, other sites in 7%. The distribution of the 215 strains was: Staphylococcus epidermidis 129 (60%), Staphylococcus capitis 24 (11%), Staphylococcus lugdunensis 21 (10%), Staphylococcus warneri 8 (4%), Staphylococcus hominis 7 (3%), Staphylococcus haemolyticus 7 (3%). More than half of the strains (52.1%) were resistant to methicillin, 40.9% to ofloxacin, 20% to rifampicin. The species most resistant to antibiotics were S. hominis, S. haemolyticus, S. epidermidis, with 69.7% of the strains resistant to methicillin and 30% simultaneously resistant to clindamycin, cotrimoxazole, ofloxacin and rifampicin. No strain was resistant to linezolid or daptomycin. In this study on CNS involved in PJIs, resistance to methicillin is greater than 50%. S. epidermidis is the most frequent and resistant species to antibiotics. Emerging species such S. lugdunensis, S. capitis and Staphylococcus caprae exhibit profiles more sensitive to antibiotics. The antibiotics most often active in vitro are linezolid and daptomycin.

Analysis of postoperative and hematogenous prosthetic joint-infection microbiological patterns in a large cohort.

OBJECTIVES: This study was undertaken to analyze prosthetic joint infection (PJI)-causing microorganisms and compare their distribution patterns according to PJI classification. METHODS: Cohort study from a single referral center for bone-and-joint infections from January 2004 to December 2015. RESULTS: Nine hundred and twenty-six patients, who developed 997 PJIs, involving the hip (62%), knee (35%) and/or shoulder (1%), were included. PJIs were classified as early postoperative (19%), late chronic (30%), hematogenous (35%) and undetermined (16%). Pathogens most frequently isolated from early-postoperative PJIs were staphylococci (57%), with 25% each Staphylococcus aureus or Staphylococcus epidermidis; 21% were polymicrobial and 10% Gram-negative rods. For late-chronic PJIs, the most frequent microbes were staphylococci (61%), predominantly S. epidermidis (35%); anaerobic bacteria were isolated from 15%; 11% were polymicrobial. Hematogenous PJIs were 99% monomicrobial. Although S. aureus was the most frequently isolated species (28%), streptococci were isolated slightly more often than staphylococci (39% vs. 36%). Among streptococci, group B streptococci were the most frequent (15%). The portal of entry was identified for 52% of hematogenous PJIs: 15% cutaneous, 11% dental, 9% gastrointestinal, 6% urinary, and 11% miscellaneous. CONCLUSION: Although a wide variety of microorganisms was isolated from PJIs, specific microbiological patterns were observed according to infection classification.

ICS classification system of infected osteosynthesis: Long-term results.

The best treatment strategy for infected osteosyntheses is still debated. While hardware removal or eventually early device exchange may be necessary in most of the cases, temporary hardware retention until fracture healing can be a valid alternative option in others. Aim of the present study is to report the long-term results of 215 patients with infected osteosyntheses, treated according to the ICS (Infection, Callus, Stability) classification in two Italian hospitals. Patients classified as ICS Type 1 (N = 83) feature callus progression and hardware stability, in spite of the presence of infection; these patients were treated with suppressive antibiotic therapy coupled with local debridement in 18.1% of the cases, and no hardware removal until bone healing. Type 2 patients (N = 75) are characterized by the presence of infection and hardware stability, but no callus progression; these patients were treated as Type 1 patients, but with additional callus stimulation therapies. Type 3 patients (N = 57), showing infection, no callus progression and loss of hardware stability, underwent removal and exchange of the fixation device. Considering only the initial treatment, performed according to the ICS classification, at a minimum 5 years follow up, 89.3% achieved bone healing and 93.5% did not show infection recurrence. The ICS classification appears as a useful and reliable tool to help standardizing the decision-making process in treating infected osteosynthesis with the most conservative approach.

[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 infections associated with neurosurgical implanted devices.

INTRODUCTION: Neurosurgical devices are increasingly used. With it, neurosurgical device-related infections gain relevance. As biofilms are involved in implant-associated infections the diagnosis and treatment is challenging and requires specific anti-biofilm concepts and management algorithms. Areas covered: The literature concerning the management of neurosurgical device-associated infections is scarce and heterogeneous treatment concepts are discussed, but no standardized diagnostic and treatment procedures exist. Therefore, we emphasize extrapolating management strategies predominantly from orthopedic device-associated infections, where the concept is better established and clinically validated. This review covers infections associated with craniotomy fixation devices, cranioplasties, external ventricular and lumbar drainages, internal shunts and neurostimulators. Expert commentary: Sonication of the removed implants significantly improves microbiological diagnosis. A combined surgical and antimicrobial management is crucial for successful treatment: appropriate surgical intervention is combined with prolonged anti-biofilm therapy of usually 12 weeks. In selected patients, new treatment algorithms enable cure of neurosurgical device-associated infections without implant removal or with a one-stage implant exchange, considerably improving the quality of patient lives.

Challenges faced in long term ventricular assist device support.

INTRODUCTION: The development of ventricular assist device (VAD) has been one of the revolutionary advancements in end-stage heart failure management. Although the device has developed and improved significantly over the last few decades, we still face multiple challenges. AREAS COVERED: This review will discuss quality of life, survival, and clinically encountered complications in patients with VAD support. The literature was extensively reviewed for studies describing the above topic area. We describe the impact of major challenges faced in VAD support and discuss their future and expectations. Expert commentary: The technological advancement of VADs has contributed to major improvement of overall survival, enhancement of quality of life and decrease of incidence of complications. It is expected that technologies will continue to evolve. At the same time, the indications for and timing of device implantation, and selection of device type are continuously important in clinical practice setting.

Cardiac device infections: definition, classification, differential diagnosis, and management.

Cardiac device infections (CDIs) continue to be a serious clinical problem, with varying terminology and different classifications constituting one of the major diagnostic and therapeutic challenges in routine clinical practice. The problem invariably arises during an attempt to estimate the extent of the infection, which in consequence determines the choice of treatment strategy (duration of antibiotic therapy). The most serious form of CDI is lead-related infective endocarditis (LRIE). There are no clearly established diagnostic criteria for this disease; the available Duke University criteria are difficult to apply in patients with a suspicion of LRIE because of low sensitivity. As the treatment of LRIE is expensive and troublesome, there is a tendency to underdiagnose this condition and seek any intermediary forms between local pocket infection and definite LRIE. The present review includes suggestions for the systematization of CDIs with a clear definition of LRIE as a separate and most severe entity among CDIs.

The results of two-stage revision TKA using Ceftazidime-Vancomycin-impregnated cement articulating spacers in Tsukayama Type II periprosthetic joint infections.

PURPOSE: This study examined the success and factors associated with failure, of using cement spacers impregnated with high-dose Ceftazidime and Vancomycin when performing two-stage revision for infected total knee arthroplasty (TKA). METHODS: A retrospective analysis was performed using a prospectively collected database of 82 patients (median age 68 years, range 39-87) with a confirmed deep TKA infection treated with a two-stage revision. All cement spacers were impregnated with high-dose Ceftazidime and Vancomycin. The rate of success was recorded-an association between failure of treatment, and patient factors, previous surgical treatment, and microbial characteristics was sought. RESULTS: The mean time to infection from index arthroplasty was 45 months (range 3-240). The initial two-stage revision was successful in 70/82 patients (85.4 %), who remained free of infection at average follow-up of 36.2 months (range 24-85). A second two-stage revision for infection was required in 12/82 patients (14.6 %), which was successful in 4/12 (33 %). A third two-stage revision was performed in three patients, all of whom had a polymicrobial infection of which only one patient had successful eradication of infection. Recurrent infection was correlated with irrigation and debridement with implant retention prior to initial two-stage revision (p < 0.01), polymicrobial infections (p = 0.035), and infections presenting <6 months after index surgery (p = 0.031). No correlation was seen with age, BMI, type of organism, diabetes mellitus, or Charlson Comorbidity Index. CONCLUSION: The findings of this study suggest that the combination of Ceftazidime and Vancomycin in cement spacers is as efficacious as other published single or combined antibiotic mixtures, which is clinically relevant to clinicians treating this difficult problem in the setting of patients with compromised renal function.

Do hip prosthesis related infection codes in administrative discharge registers correctly classify periprosthetic hip joint infection?

PURPOSE: Administrative discharge registers could be a valuable and easily accessible single-sources for research data on periprosthetic hip joint infection. The aim of this study was to estimate the positive predictive value of the International Classification of Disease 10th revision (ICD-10) periprosthetic hip joint infection diagnosis code in the Danish National Patient Register. METHODS: Patients were identified with an ICD-10 discharge diagnosis code of T84.5 ("Infection and inflammatory reaction due to internal joint prosthesis") in association with hip-joint associated surgical procedure codes in The Danish National Patient Register. Medical records of the identified patients (n = 283) were verified for the existence of a periprosthetic hip joint infection. Positive predictive values with 95% confidence intervals (95% CI) were calculated. RESULTS: A T84.5 diagnosis code irrespective of the associated surgical procedure code had a positive predictive value of 85% (95% CI: 80-89). Stratified to T84.5 in combination with an infection-specific surgical procedure code the positive predictive value increased to 86% (95% CI: 80-91), and in combination with a noninfection-specific surgical procedure code decreased to 82% (95% CI: 72-89). CONCLUSIONS: Misclassification must be expected and taken into consideration when using administrative discharge registers for epidemiological research on periprosthetic hip joint infection. We believe that the periprosthetic hip joint infection diagnosis code can be of use in future single-source register based studies, but preferably should be used in combination with alternate data sources to ensure higher validity.

Is a Revision a Revision? An Analysis of National Arthroplasty Registries' Definitions of Revision.

BACKGROUND: The reported survival of implants depends on the definition used for the endpoint, usually revision. When screening through registry reports from different countries, it appears that revision is defined quite differently. QUESTIONS/PURPOSES: The purposes of this study were to compare the definitions of revision among registry reports and to apply common clinical scenarios to these definitions. METHODS: We downloaded or requested reports of all available national joint registries. Of the 23 registries we identified, 13 had published reports that were available in English and were beyond the pilot phase. We searched these registries' reports for the definitions of the endpoint, mostly revision. We then applied the following scenarios to the definition of revision and analyzed if those scenarios were regarded as a revision: (A) wound revision without any addition or removal of implant components (such as hematoma evacuation); (B) exchange of head and/or liner (like for infection); (C) isolated secondary patella resurfacing; and (D) secondary patella resurfacing with a routine liner exchange. RESULTS: All registries looked separately at the characteristic of primary implantation without a revision and 11 of 13 registers reported on the characteristics of revisions. Regarding the definition of revision, there were considerable differences across the reports. In 11 of 13 reports, the primary outcome was revision of the implant. In one registry the primary endpoint was "reintervention/revision" while another registry reported separately on "failure" and "reoperations". In three registries, the definition of the outcome was not provided, however in one report a results list gave an indication for the definition of the outcome. Wound revision without any addition or removal of implant components (scenario A) was considered a revision in three of nine reports that provided a clear definition on this question, whereas two others did not provide enough information to allow this determination. Exchange of the head and/or liner (like for infection; scenario B) was considered a revision in 11 of 11; isolated secondary patella resurfacing (scenario C) in six of eight; and secondary patella resurfacing with routine liner exchange (scenario D) was considered a revision in nine of nine reports. CONCLUSIONS: Revision, which is the most common main endpoint used by arthroplasty registries, is not universally defined. This implies that some reoperations that are considered a revision in one registry are not considered a revision in another registry. Therefore, comparisons of implant performance using data from different registries have to be performed with caution. We suggest that registries work to harmonize their definitions of revision to help facilitate comparisons of results across the world's arthroplasty registries.