Patients with infected arthroplasties are normally treated with a two-stage exchange procedure using polymethylmethacrylate bone cement spacers impregnated with antibiotics. However, spacers may act as a foreign body to which micro-organisms may adhere and grow. In this study it was hypothesised that subclinical infection may be diagnosed with sonication of the surface biofilm of the spacer. The aims were to assess the presence of subclinical infection through sonication of the spacer at the time of a second-stage procedure, and to determine the relationship between subclinical infection and the clinical outcome. Of 55 patients studied, 11 (20%) were diagnosed with subclinical infection. At a mean follow-up of 12 months (interquartile range 6 to 18), clinical failure was found in 18 (32.7%) patients. Of the patients previously diagnosed with subclinical infection, 63% (7 of 11) had failed compared with 25% (11 of 44) of those without subclinical infection (odds ratio 5.25, 95% confidence interval 1.29 to 21.4, p = 0.021). Sonication of the biofilm of the surface of the spacer is useful in order to exclude subclinical infection and therefore contributes to improving the outcome after two-stage procedures.

Aims. Debridement, antibiotics, and implant retention (DAIR) is a widely accepted form of surgical treatment for patients with an early periprosthetic joint infection (PJI) after primary arthroplasty. The outcome of DAIR after revision arthroplasty, however, has not been reported. The aim of this study was to report the success rate of DAIR after revision arthroplasty with a follow-up of two years. Methods. This retrospective study, conducted at the Sint Maartenskliniek, Nijmegen, the Netherlands, included 88 patients who underwent DAIR within 90 days of revision total hip or total knee arthroplasty between 2012 and 2019. Details of the surgical procedures and PJI were collected. Univariate analysis and a subgroup analysis of the culture-positive group were performed. Kaplan-Meier survivorship curves were constructed. Results. The overall success rate of DAIR, with respect to the retention of components and the cure of infection, was 68% after two years. DAIR performed with an interval of > 30 days after the index revision procedure (odds ratio (OR) 0.24 (95% confidence interval (CI) 0.08 to 0.72); p = 0.008), a repeated DAIR within 90 days (OR 0.37 (95% CI 0.14 to 0.97); p = 0.040), and the use of an immunosuppressive agent (OR 0.13 (95% CI 0.02 to 0.67); p = 0.012) were associated with a significantly reduced success rate. In the culture-positive group, a mismatch between the antibiotic treatment and the susceptibility of the organism was associated with a significantly lower success rate (OR 0.13 (95% CI 0.03 to 0.62); p = 0.007). Conclusion. DAIR is an acceptable form of surgical treatment for patients with a suspected early PJI after revision arthroplasty of the hip or knee. DAIRs performed after a prolonged interval, multiple DAIRs, and antibiotic mismatches were significantly associated with an increased risk of failure. Optimization of the host immune response and the prevention of antibiotic mismatch are modifiable factors that may improve the outcome. The high rate of mismatches was an important finding, underlining the need for a review of the local microbiological data, which might improve the outcome. Cite this article: Bone Joint J 2022;104-B(4):464–471

Aims. Fungal and mycobacterial periprosthetic joint infections (PJI) are rare events. Clinicians are wary of missing these diagnoses, often leading to the routine ordering of fungal and mycobacterial cultures on periprosthetic specimens. Our goal was to examine the utility of these cultures and explore a modern bacterial culture technique using bacterial blood culture bottles (BCBs) as an alternative. Methods. We performed a retrospective review of patients diagnosed with hip or knee PJI between 1 January 2010 and 31 December 2019, at the Mayo Clinic in Rochester, Minnesota, USA. We included patients aged 18 years or older who had fungal, mycobacterial, or both cultures performed together with bacterial cultures. Cases with positive fungal or mycobacterial cultures were reviewed using the electronic medical record to classify the microbiological findings as representing true infection or not. Results. There were 2,067 episodes of PJI diagnosed within the study period. A total of 3,629 fungal cultures and 2,923 mycobacterial cultures were performed, with at least one of these performed in 56% of episodes (n = 1,157). Test positivity rates of fungal and mycobacterial cultures were 5% (n = 179) and 1.2% (n = 34), respectively. After a comprehensive review, there were 40 true fungal and eight true mycobacterial PJIs. BCB were 90% sensitive in diagnosing true fungal PJI and 100% sensitive in detecting rapidly growing mycobacteria (RGM). Fungal stains were performed in 27 true fungal PJI but were only positive in four episodes (14.8% sensitivity). None of the mycobacterial stains was positive. Conclusion. Routine fungal and mycobacterial stains and cultures should not be performed as they have little clinical utility in the diagnosis of PJI and are associated with significant costs. Candida species and RGM are readily recovered using BCB. More research is needed to predict rare non-Candida fungal and slowly growing mycobacterial PJI that warrant specialized cultures. Cite this article: Bone Joint J 2022;104-B(1):53–58

Aims. The diagnosis of periprosthetic joint infection (PJI) can be difficult. All current diagnostic tests have problems with accuracy and interpretation of results. Many new tests have been proposed, but there is no consensus on the place of many of these in the diagnostic pathway. Previous attempts to develop a definition of PJI have not been universally accepted and there remains no reference standard definition. Methods. This paper reports the outcome of a project developed by the European Bone and Joint Infection Society (EBJIS), and supported by the Musculoskeletal Infection Society (MSIS) and the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Implant-Associated Infections (ESGIAI). It comprised a comprehensive review of the literature, open discussion with Society members and conference delegates, and an expert panel assessment of the results to produce the final guidance. Results. This process evolved a three-level approach to the diagnostic continuum, resulting in a definition set and guidance, which has been fully endorsed by EBJIS, MSIS, and ESGIAI. Conclusion. The definition presents a novel three-level approach to diagnosis, based on the most robust evidence, which will be useful to clinicians in daily practice. Cite this article: Bone Joint J 2021;103-B(1):18–25

Aims. The success rates of two-stage revision arthroplasty for infection have evolved since their early description. The implementation of internationally accepted outcome criteria led to the readjustment of such rates. However, patients who do not undergo reimplantation are usually set aside from these calculations. The aim of this study was to investigate the outcomes of two-stage revision arthroplasty when considering those who do not undergo reimplantation, and to investigate the characteristics of this subgroup. Methods. A retrospective cohort study was conducted. Patients with chronic hip or knee periprosthetic joint infection (PJI) treated with two-stage revision between January 2010 and October 2018, with a minimum follow-up of one year, were included. Variables including demography, morbidity, microbiology, and outcome were collected. The primary endpoint was the eradication of infection. Patients who did not undergo reimplantation were analyzed in order to characterize this subgroup better. Results. A total of 162 chronic PJIs were included in the study. After a mean follow-up of 57.3 months (12.1 to 115.7), 18 patients (11.1%) did not undergo reimplantation, due either to medical issues (10), the patient’s choice (4), or death (4). When only considering those who underwent reimplantation, the success rate was 80.6%. However, when those who did not undergo reimplantation were included, the success rate dropped to 71.6%. Advanced age, American Society of Anesthesiologists grade ≥ III, McPherson’s C host, and Gram-negative related PJI were independent risk factors for retention of the spacer. The mortality was higher in the non-reimplanted group. Conclusion. The real success rate of two-stage revision may not be as high as previously reported. The exclusion of patients who do not undergo reimplantation resulted in a 9% overestimation of the success rate in this series. Many comorbidity-related risk factors for retention of the spacer were identified, as well as higher death rates in this group. Efforts should be made to optimize these patients medically in order to increase reimplantation and success rates, while decreasing mortality. Cite this article: Bone Joint J 2020;102-B(12):1682–1688

Aims. Fungal prosthetic joint infections (PJIs) are rare and account for about 1% of total PJIs. Our aim was to present clinical and microbiological results in treating these patients with a two-stage approach and antifungal spacers. Patients and Methods. We retrospectively reviewed our institutional database and identified 26 patients with positive fungal cultures and positive Musculoskeletal Infection Society (MSIS) criteria for PJI who were treated between 2009 and 2017. We identified 18 patients with total hip arthroplasty (THA) and eight patients with total knee arthroplasty (TKA). The surgical and antifungal treatment, clinical and demographic patient data, complications, relapses, and survival were recorded and analyzed. Results. The median follow-up was 33 months. The success rate was 38.5% (10/26). Fluconazole resistance was found in 15%. Bacterial co-infection was common in 44% of patients for THA and 66% of patients with TKA. Mortality, reoperations, and treatment failure were common complications. Conclusion. Treatment with a two-stage exchange is a possible option for treatment, although fungal infections have a high failure rate. Therapeutic factors for treatment success remain unclear. Cite this article: Bone Joint J 2019;101-B:589–595

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

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The aim of this study was to evaluate the optimal deep tissue specimen sample number for histopathological analysis in the diagnosis of periprosthetic joint infection (PJI).

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The aim of this study was to evaluate the diagnostic accuracy of the absolute synovial polymorphonuclear neutrophil cell (PMN) count for the diagnosis or exclusion of periprosthetic joint infection (PJI) after total hip (THA) or knee arthroplasty (TKA).

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A higher failure rate has been reported in haematogenous periprosthetic joint infection (PJI) compared to non-haematogenous PJI. The reason for this difference is unknown. We investigated the outcome of haematogenous and non-haematogenous PJI to analyze the risk factors for failure in both groups of patients.

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Total femoral arthroplasty (TFA) is a rare procedure used in cases of significant femoral bone loss, commonly from cancer, infection, and trauma. Low patient numbers have resulted in limited published work on long-term outcomes, and even less regarding TFA undertaken for non-oncological indications. The aim of this study was to evaluate the long-term clinical outcomes of all TFAs in our unit.

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Our aim was to estimate the total costs of all hospitalizations for treating periprosthetic joint infection (PJI) by main management strategy within 24 months post-diagnosis using activity-based costing. Additionally, we investigated the influence of individual PJI treatment pathways on hospital costs within the first 24 months.

Aims. Tissue responses to debris formed by abrasion of polymethylmethacrylate (PMMA) spacers at two-stage revision arthroplasty for prosthetic joint infection are not well described. We hypothesised that PMMA debris induces immunomodulation in periprosthetic tissues. Patients and Methods. Samples of tissue were taken during 35 two-stage revision arthroplasties (nine total hip and 26 total knee arthroplasties) in patients whose mean age was 67 years (44 to 85). Fourier transform infrared microscopy was used to confirm the presence of PMMA particles. Histomorphometry was performed using Sudan Red and Haematoxylin-Eosin staining. CD-68, CD-20, CD-11(c), CD-3 and IL-17 antibodies were used to immunophenotype the inflammatory cells. All slides were scored semi-quantitatively using the modified Willert scoring system. Results. The mean CD-68 scores did not show any significant change during the six weeks between the stages. Perivascular and diffuse scores showed significant difference in CD-3, CD-20, CD-11(c) and IL-17. At the time of re-implantation, a shift in the pattern of the expression of dendritic cells towards a perivascular arrangement and towards the periphery of PMMA particles was observed. Positive microbiological cultures were found at the time of re-implantation in three patients. Five further revisions were required for other reasons. Conclusion. Our results represent a biological reaction of the synovial tissues to spacers with a less diffuse expression of dendritic cells and an increased expression of perivascular lymphocytes. The use of spacers in two-stage revision for infection probably induces an immunomodulation of synovial tissues. Cite this article: Bone Joint J 2016;98-B:1062–8

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The aim of this study was to estimate the 90-day periprosthetic joint infection (PJI) rates following total knee arthroplasty (TKA) and total hip arthroplasty (THA) for osteoarthritis (OA).

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Removal of infected components and culture-directed antibiotics are important for the successful treatment of chronic periprosthetic joint infection (PJI). However, as many as 27% of chronic PJI patients yield negative culture results. Although culture negativity has been thought of as a contraindication to one-stage revision, data supporting this assertion are limited. The aim of our study was to report on the clinical outcomes for one-stage and two-stage exchange arthroplasty performed in patients with chronic culture-negative PJI.

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Calprotectin (CLP) is produced in neutrophils and monocytes and released into body fluids as a result of inflammation or infection. The aim of this study was to evaluate the utility of blood and synovial CLP in the diagnosis of chronic periprosthetic joint infection (PJI).

Cut-off values with highest sensitivity and specificity for the synovial fluid white cell and differential count will facilitate the accurate diagnosis of infection in total knee (TKR) and total hip replacement (THR). All patients undergoing revision TKR or THR for suspected prosthetic joint infection between 2009 and 2011 at two hospitals were identified. A total of 75 patients were included with a mean age of 70.3 years (38 to 89). Synovial fluid was aspirated pre-operatively and peri-prosthetic tissue samples were taken intra-operatively for histological and microbiological examination. Receiver operating characteristic (ROC) plots were constructed for white cell and differential counts in aspirated fluid. The optimal cut-off for TKR and THR was 1590 white cells/µl and 65% neutrophilia. The white cell count cut-off value identified for THR was notably lower than previously quoted in the literature. A cut-off value for white cell count in synovial aspirate in suspected prosthetic joint infection of between 1100 and 1700 white cells/µl is likely to be applicable to both THR and TKR. Cite this article: Bone Joint J 2013;95-B:554–7

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Metagenomic next-generation sequencing (mNGS) is useful in the diagnosis of infectious disease. However, while it is highly sensitive at identifying bacteria, it does not provide information on the sensitivity of the organisms to antibiotics. The purpose of this study was to determine whether the results of mNGS can be used to guide optimization of culture methods to improve the sensitivity of culture from intraoperative samples.

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The primary aim was to assess the rate of postoperative COVID-19 following hip and knee arthroplasty performed in March 2020 in the UK. The secondary aims were to assess whether there were clinical factors associated with COVID-19 status, the mortality rate of patients with COVID-19, and the rate of potential COVID-19 in patients not presenting to healthcare services.

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Biopsy of the periprosthetic tissue is an important diagnostic tool for prosthetic joint infection (PJI) as it enables the detection of the responsible microorganism with its sensitivity to antibiotics. We aimed to investigate how often the bacteria identified in the tissue analysis differed between samples obtained from preoperative biopsy and intraoperative revision surgery in cases of late PJI; and whether there was a therapeutic consequence.