Aims. This aim of this study was to analyze the detection rate of rare pathogens in bone and joint infections (BJIs) using metagenomic next-generation sequencing (mNGS), and the impact of mNGS on clinical diagnosis and treatment. Methods. A retrospective analysis was conducted on 235 patients with BJIs who were treated at our hospital between January 2015 and December 2021. Patients were divided into the no-mNGS group (microbial culture only) and the mNGS group (mNGS testing and microbial culture) based on whether mNGS testing was used or not. Results. A total of 147 patients were included in the no-mNGS group and 88 in the mNGS group. The mNGS group had a higher detection rate of rare pathogens than the no-mNGS group (21.6% vs 10.2%, p = 0.016). However, the mNGS group had lower rates of antibiotic-related complications, shorter hospital stays, and higher infection control rates compared with the no-mNGS group (p = 0.017, p = 0.003, and p = 0.028, respectively), while there was no significant difference in the duration of antibiotic use (p = 0.957). In culture-negative cases, the mNGS group had lower rates of antibiotic-related complications, shorter hospital stays, and a higher infection control rate than the no-mNGS group (p = 0.036, p = 0.033, p = 0.022, respectively), while there was no significant difference in the duration of antibiotic use (p = 0.748). Conclusion. mNGS improves detection of rare pathogens in BJIs. mNGS testing reduces antibiotic-related complications, shortens hospital stay and antibiotic use duration, and improves treatment success rate, benefits which are particularly evident in culture-negative cases. Cite this article: Bone Joint Res 2024;13(8):401–410

Aims. The French registry for complex bone and joint infections (C-BJIs) was created in 2012 in order to facilitate a homogeneous management of patients presented for multidisciplinary advice in referral centres for C-BJI, to monitor their activity and to produce epidemiological data. We aimed here to present the genesis and characteristics of this national registry and provide the analysis of its data quality. Methods. A centralized online secured database gathering the electronic case report forms (eCRFs) was filled for every patient presented in multidisciplinary meetings (MM) among the 24 French referral centres. Metrics of this registry were described between 2012 and 2016. Data quality was assessed by comparing essential items from the registry with a controlled dataset extracted from medical charts of a random sample of patients from each centre. Internal completeness and consistency were calculated. Results. Between 2012 and 2016, 30,607 presentations in MM were recorded corresponding to 17,748 individual patients (mean age 62.1 years (SD 18.4); 10,961 (61.8%) males). BJI was considered as complex for 63% of cases (n = 19,355), and 13,376 (44%) had prosthetic joint infections (PJIs). The controlled dataset, available for 19 centres, included 283 patients. Global consistency and completeness were estimated at 88.2% and 88.9%, respectively, considering missing items in the eCRFs as negative results. Conclusion. This national registry is one of the largest prospective databases on BJI and its acceptable data quality parameters allow further use for epidemiological purposes. Cite this article: Bone Joint Res 2020;9(9):635–644

Aims. Musculoskeletal infection is a devastating complication in both trauma and elective orthopaedic surgeries that can result in significant morbidity. Aim of this study was to assess the effectiveness and complications of local antibiotic impregnated dissolvable synthetic calcium sulphate beads (Stimulan Rapid Cure) in the hands of different surgeons from multiple centres in surgically managed bone and joint infections. Methods. Between January 2019 and December 2022, 106 patients with bone and joint infections were treated by five surgeons in five hospitals. Surgical debridement and calcium sulphate bead insertion was performed for local elution of antibiotics in high concentration. In all, 100 patients were available for follow-up at regular intervals. Choice of antibiotic was tailor made for each patient in consultation with microbiologist based on the organism grown on culture and the sensitivity. In majority of our cases, we used a combination of vancomycin and culture sensitive heat stable antibiotic after a thorough debridement of the site. Primary wound closure was achieved in 99 patients and a split skin graft closure was done in one patient. Mean follow-up was 20 months (12 to 30). Results. Overall, six out of 106 patients (5.6%) presented with sepsis and poorly controlled comorbid conditions, and died in the hospital within few days of index surgery. Out of the remaining 100 patients, control of infection was achieved in 95 patients (95%). Persistence of infection was noted in five (5%) patients. Out of these 95 patients that had good control of infection, four patients (4.2%) with gap nonunion needed Masquelet procedure to achieve union. Conclusion. Our multicentre experience confirmed that surgical debridement along with calcium sulphate bead insertion was effective in treating bone and joint infections without any side effects and complications. Cite this article: Bone Jt Open 2023;4(7):516–522

Acute bone and joint infections in children are serious, and misdiagnosis can threaten limb and life. Most young children who present acutely with pain, limping, and/or loss of function have transient synovitis, which will resolve spontaneously within a few days. A minority will have a bone or joint infection. Clinicians are faced with a diagnostic challenge: children with transient synovitis can safely be sent home, but children with bone and joint infection require urgent treatment to avoid complications. Clinicians often respond to this challenge by using a series of rudimentary decision support tools, based on clinical, haematological, and biochemical parameters, to differentiate childhood osteoarticular infection from other diagnoses. However, these tools were developed without methodological expertise in diagnostic accuracy and do not consider the importance of imaging (ultrasound scan and MRI). There is wide variation in clinical practice with regard to the indications, choice, sequence, and timing of imaging. This variation is most likely due to the lack of evidence concerning the role of imaging in acute bone and joint infection in children. We describe the first steps of a large UK multicentre study, funded by the National Institute for Health Research, which seeks to integrate definitively the role of imaging into a decision support tool, developed with the assistance of individuals with expertise in the development of clinical prediction tools. Cite this article: Bone Joint J 2023;105-B(3):227–229

Antibiotic resistance represents a threat to human health. It has been suggested that by 2050, antibiotic-resistant infections could cause ten million deaths each year. In orthopaedics, many patients undergoing surgery suffer from complications resulting from implant-associated infection. In these circumstances secondary surgery is usually required and chronic and/or relapsing disease may ensue. The development of effective treatments for antibiotic-resistant infections is needed. Recent evidence shows that bacteriophage (phages; viruses that infect bacteria) therapy may represent a viable and successful solution. In this review, a brief description of bone and joint infection and the nature of bacteriophages is presented, as well as a summary of our current knowledge on the use of bacteriophages in the treatment of bacterial infections. We present contemporary published in vitro and in vivo data as well as data from clinical trials, as they relate to bone and joint infections. We discuss the potential use of bacteriophage therapy in orthopaedic infections. This area of research is beginning to reveal successful results, but mostly in nonorthopaedic fields. We believe that bacteriophage therapy has potential therapeutic value for implant-associated infections in orthopaedics. Cite this article: Bone Joint J 2021;103-B(2):234–244

Aims. Trained immunity confers non-specific protection against various types of infectious diseases, including bone and joint infection. Platelets are active participants in the immune response to pathogens and foreign substances, but their role in trained immunity remains elusive. Methods. We first trained the innate immune system of C57BL/6 mice via intravenous injection of two toll-like receptor agonists (zymosan and lipopolysaccharide). Two, four, and eight weeks later, we isolated platelets from immunity-trained and control mice, and then assessed whether immunity training altered platelet releasate. To better understand the role of immunity-trained platelets in bone and joint infection development, we transfused platelets from immunity-trained mice into naïve mice, and then challenged the recipient mice with Staphylococcus aureus or Escherichia coli. Results. After immunity training, the levels of pro-inflammatory cytokines (tumour necrosis factor alpha (TNF-α), interleukin (IL)-17A) and chemokines (CCL5, CXCL4, CXCL5, CXCL7, CXCL12) increased significantly in platelet releasate, while the levels of anti-inflammatory cytokines (IL-4, IL-13) decreased. Other platelet-secreted factors (e.g. platelet-derived growth factor (PDGF)-AA, PDGF-AB, PDGF-BB, cathepsin D, serotonin, and histamine) were statistically indistinguishable between the two groups. Transfusion of platelets from trained mice into naïve mice reduced infection risk and bacterial burden after local or systemic challenge with either S. aureus or E. coli. Conclusion. Immunity training altered platelet releasate by increasing the levels of inflammatory cytokines/chemokines and decreasing the levels of anti-inflammatory cytokines. Transfusion of platelets from immunity-trained mice conferred protection against bone and joint infection, suggesting that alteration of platelet releasate might be an important mechanism underlying trained immunity and may have clinical implications. Cite this article: Bone Joint Res 2022;11(2):73–81

Aim

Corynebacterium is a rare etiologic agent of BJI. We aimed to describe this rare clinical condition and to assess treatment failure determinants.

Aim. To investigate the impact of waiting for surgical treatment for bone and joint infection (BJI) on patient self-reported quality of life (QoL). Method. Patients presenting to clinic between January 2019 and February 2020 completed the EuroQol EQ-5D-5L questionnaire. Patients were divided into three groups: surgery performed; on the waiting list for surgery; or decision for non-operative management. All patients were followed-up for 2 years. The EQ-index score was calculated and change from presentation to 1-year and 2-year follow-up was compared across the 3 groups. Mortality at final follow-up was measured in all groups. Results. 188 patients were included. Of these, 98 had an operation performed, 50 were on the waiting list for surgery but did not receive an operation and 40 were treated non-operatively. At presentation, all three groups had similar EQ-5D-5L index scores (surgery:0.412 SD0.351; waiting list:0.510 SD0.320; non-operative management: 0.467 SD0.354; p=0.269). There was a significant improvement in QoL in patients who underwent surgery when compared to their pre-operative state (mean increase of EQ-index score +0.241 in the first year (SD0.333, p<0.001) and +0.259 (SD0.294, p<0.001) in the second year. Patients on the waiting list for surgery had a small time-dependent decrease in EQ-index score at 1 year (−0.077, SD0.282, p=0.188) and 2 years (−0.140, SD0.359, p=0.401). Patients treated non-operatively had similar changes in EQ-index scores at 1 year (−0.052, SD0.309, p=0.561) and 2 years (−0.146, SD 0.234, p=0.221). Patients who had surgery had significantly better QoL at 2-years after treatment compared to other groups (mean EQ-index scores: surgery performed 0.671 vs. waiting list 0.431, p<0.001; surgery performed vs. non-operative management 0.348, p<0.001). Mortality in the operated group was 3.1%, which was similar to patients who were on the waiting list for surgery (6.5%, p=0.394) but lower than patients who were non-operatively managed (14.7%, p=0.014). Conclusions. The Covid-19 pandemic created long waiting times for some patients. Selecting patients with BJI who can safely wait for surgery is difficult. QoL for patients with BJI deteriorates over time if surgery is delayed or not performed. When patients decline surgery, they should be counselled that their QoL is likely to be impaired over time. The relationship between waiting time and mortality merits further study

Aim. To assess whether recurrence of PJI and osteomyelitis impacts patient-reported quality of life (QoL). Method. We studied patients receiving surgical treatment for confirmed PJI or osteomyelitis in one of 26 centres in the UK. Patients completed the EQ-5D-3L questionnaire, directly after surgery, at day 14, day 42, day 120 and day 365 after surgery and were assessed for evidence of recurrence. Results. Of 621 patients with PJI, 99 had recurrent infection (15.9%). Patients with recurrence reported significantly lower QoL at one year after surgery compared to those without recurrence (EQ-5D-3L index score with recurrence: 0.368, SD0.344 vs. no recurrence: 0.592, SD0.315, p<0.001). Patients were grouped based on the timing of their recurrence: <42 days (n=27); 42–120 (n=28); or >120 days (n=44) post-surgery. At the time-point immediately preceding the diagnosis of recurrence, QoL was significantly lower than in corresponding patients without recurrence (recurrence <42 days, p<0.05; 42–120 days, p<0.001; >120 days, p<0.05). In 358 cases of osteomyelitis, 39 patients had recurrent infection (10.9%). Recurrence of osteomyelitis produced significantly lower QoL at one year after surgery compared to patients without recurrent infection (EQ-5D-3L for recurrence: 0.385, SD0.345 vs. no recurrence: 0.634, SD0.349, p<0.001). Patients with recurrence after 120 days (n=21) reported significantly lower QoL than those with no recurrence at the time-point immediately preceding the diagnosis of recurrence (p<0.01). In contrast to patients with PJI, patients with osteomyelitis who had recurrence diagnosed before 120 days (n=18) reported similar outcome scores to patients who did not have recurrence. Conclusion. Failure to eradicate infection greatly affects patient QoL. This study supports the monitoring of EQ-5D-3L among patients treated for bone and joint infections; patients with poorer QoL at follow up should prompt a low threshold for investigation to assess whether recurrence or continued infection is the underlying cause

Between 1980 and 1984 nine adult patients in the renal unit of Guy's Hospital developed bone and joint infection. The commonest site of infection was the spine. In this series two patients died, a mortality of 22%. The purpose of this paper is to illustrate the pitfalls in the diagnosis and management of bone and joint infection in patients with renal failure and renal transplants

To propose a national specification for hospitals which offer treatment of complex bone and joint infections to adults. Patients with bone and joint infections are treated in a wide variety of hospitals in the UK. A few have developed services with infection physicians, microbiology laboratory support and dedicated orthopaedic and plastic surgeons working together to deliver a multidisciplinary care pathway. However, many patients are treated in non-specialist units leading to multiple, often unsuccessful procedures with long hospital stays, high costs and additional pain and disability. Inappropriate antibiotic therapy without adequate surgery risks antibiotic resistance. A draft specification was written defining the types of patients who should be referred to a specialist unit for treatment. A description of the components which must be available to treat these cases (staffing, expertise, diagnostic support, outcome assessment and governance structure) was proposed. This draft was circulated to infection units in the UK for consideration and agreed with the Health Department in England. Complex bone and joint infections would be best served nationally by 3–6 networks, each with a single specialist centre. This is similar to national arrangements for bone sarcoma treatment. Patients to be referred will include those with:. Chronic osteomyelitis (long bone, pelvis, spine). Chronic destructive septic arthritis. Complex prosthetic joint infections (multiple co-morbidities, difficult/multi-resistant organisms, multiply operated or failed revision surgery). Infected fractures and non-unions. Specialist units should have:. Orthopaedic surgeons who specialise in infection (joint revision, Ilizarov techniques, etc). Infection physicians who can treat medically unwell patients with complex co-mordidities and multi-resistant infections. Plastic surgeons with experience in difficult microsurgical reconstruction techniques. Scheduled (at least weekly) meetings of all of the above, with a radiologist to discuss new referrals and complex cases. A home IV therapy service. Dedicated in-patient beds staffed by infection trained staff. Multi-disciplinary (one-stop) out-patient clinics. Quality measures assessed, including PROMS, clinical success rates, and functional outcome. Education and research programmes. This service specification is a tool for developing regional units. It facilitates the creation of designated centres in a national network (hub and spoke model). This service specification has been agreed and published by NHS England

Aim. bone and joint infection (BJI) in aging population, continues to be associated with significant morbi-mortality. In western Europeans countries, the Gram positive BJI are preponderant. Vancomycin was the “gold standard” and the full treatment requires prolonged antibiotic therapy. Dalbavancin is a semi-synthetic lipoglycopeptideanalog of teicoplanin class of antibiotics with bactericidal activity and a long half-life. The use of dalbavancin in BJI could be an option. Methods. during November 2017 and April 2019, Dalbavancin was used in monotherapy as salvage option in BJI: 1500 mg, 1. st. (D1) and 8. th. day (D8), repeated if needed. The clinical and biological follow up was for 6 months if osteomyelitis or BJI without prosthesis and 1 year if prosthesis (PJI). Results. the demographics of 16 patients are: 75.0% men (n=12), mean age 77.8 years [64–90], 37.5% (n=6) diabetes, 68.8% (n=11) renal failure, 37.5% (n=6) atrial fibrillation, 18.8% (n=3) cardiac bioprosthesis, 31.2% (n=5) lower limb arteriopathy, and one patient with active neoplasia. The BJI characteristic's: 50% (n=8) secondary to health care;5 vertebral osteomyelitis; 12 lower limb BJI : 8 joint infection of witch 6 PJI (4 knee, 2 hip) and 4 foot osteomyelitis; 2 shoulder PJI; 3 patients had 2 or more localisations of BJI. In 68.8% (11/16) BJI, bacteraemia occurred with 68.8% (n=11) of possible or certain infective endocarditis (Duke criteria) and 37.5% (n=6) of deep abscess. The DAIR was of 83.4% (5/6). Monobacterian biopsy in 75.0% (n=12). Out of 32 micro-organisms, 25 were Dalbavancin susceptible:56.0% (14/25) Staphylococcus aureus (10 methicillin susceptible), 3 Streptococcus, 5 Enterococcus faecalis, 2 Corynebacterium, 1 coagulase negative staphylococcus. Mean of 1. st. antibiotherapy: 18.3 days [0–49], with 2 patients who had dalbavancine as only antibiotic. Number of dalbavancine doses: 75% (n=12) patients had 2 injection (D1, D8), 18.8% (n=3), 4 injections D1, D8, D28 and D35 and 1 patient had one dose. Principal reason of changing by dalbavancine: 50% (8/16) poor tolerance of antibiotics, 12.5% (2/16) poor compliance of patient, 18.8% (3/16) poor efficacy of 1. st. antibiotherapy, 18.8 %(3/16) only for the patient's comfort. Clinically success: 75% (12/16) with 5 patients in follow up today. Three patients died and one is cured with teicoplanin and rifampicin. Three patients presented side effects: one diarrhea, one headache and one transient asthenia. No renal damage was found and no allergy. Conclusion. This report highlights the potential role of dalbavancin in treating unstable and weak patients who require long-term antimicrobial therapy with fewer antibiotic choices

Aim. There have been many attempts to define the criteria by which prosthetic joint infection (PJI) is diagnosed. Our aim is to validate the 2021 European Bone and Joint Infection Society (EBJIS) definition of PJI. Method. This is a multicenter retrospective study of patients who have undergone total hip or knee revision surgery in four different European institutions between 2013–2018. Cases with less than four intraoperative microbiology samples; no preoperative/intraoperative synovial fluid differential leukocyte count or intraoperative histology were excluded. Minimum follow-up of at least two years after revision surgery if no subsequent infection and/or the need for implant removal was also required. All cases were classified using the 2021 EBJIS, the 2018 International Consensus Meeting (ICM) and the 2013 Musculoskeletal Infection Society (MSIS) PJI definitions. Results. Definitive PJI classification according to the different definitions of the 507 patients included are presented in table 1. The EBJIS definition classifies 40.4%(205/507) of the cases as confirmed infections compared to 33.9%(p=0.038) and 29.4%(p<0.001) in 2018 ICM and 2013 MSIS classifications respectively. Compared to 2018 ICM classification it also offers significantly less undetermined cases – 5.0% vs. 11.4%(p<0.001). Free from infection Kaplan-Meyer survival curve shows significantly better outcome for EBJIS unlikely compared to confirmed subgroup(p=0.031). EBJIS likely subgroup survival is not significantly different from unlikely(p=0.529) or confirmed(p=0.717) cohorts. Among the MSIS not infected cohort the newly classified EBJIS confirmed/likely cases present higher subsequent infection rate (albeit not statistically significant) when compared to EBJIS infection unlikely cases − 16.0%(13/81) vs. 10.1%(28/277). This subsequent PJI rate is similar to the MSIS infected cohort. A similar trend is not obvious within ICM 2018 not infected subgroup. Conclusions. The EBJIS 2021 definition is shown to be the most sensitive definition while also offering a smaller number of undetermined cases. Newly diagnosed infections seem to have a similar prognosis as “classically” infected cases. For any tables or figures, please contact the authors directly

Aim. Current standard of care in the management of bone and joint infection commonly includes a 4–6 week course of intravenous (IV) antibiotics but there is little evidence to suggest that oral antibiotic therapy results in worse outcomes. The primary objective was to determine whether oral antibiotics are non-inferior to IV antibiotics in this setting. Method. This was a parallel group, randomised (1:1), open label, non-inferiority trial across twenty-six NHS hospitals in the United Kingdom. Eligible patients were adults with a clinical diagnosis of bone, joint or orthopaedic metalware-associated infection who would ordinarily receive at least six weeks of antibiotics and who had received ≤7 days of IV therapy from the date of definitive surgery (or the start of planned curative treatment in patients managed non-operatively). Participants were randomised to receive either oral or IV antibiotics for the first 6 weeks of therapy. Follow-on oral therapy was permitted in either arm. The primary outcome was the proportion of participants experiencing definitive treatment failure within one year of randomisation. The non-inferiority margin was set at 7.5%. Results. Of 1054 participants randomised (527 to each arm) endpoint data were available for 1015 (96.30%). Definitive treatment failure was identified in 141/1015 (13.89%) participants, 74/506 (14.62%) of those randomised to IV therapy and 67/509 (13.16%) of those randomised to oral therapy. In the intention to treat analysis, the imputed risk difference (PO-IV) for definitive treatment failure was −1.38% (90% CI: −4.94, 2.19), thus meeting the non-inferiority criterion (i.e. the upper limit of 95%CI being <7.5%). A complete cases analysis, a per-protocol analysis and sensitivity analyses for missing data confirmed this result. With the exception of intravenous catheter complications, there was no significant difference between the two arms in the incidence of serious adverse events (SAEs). Health economic analysis suggests that the non-surgical treatment costs over one year for patients randomised to oral therapy were approximately £2,700 less than those of IV therapy. Conclusions. Oral antibiotic therapy is non-inferior to IV therapy when used during the first six weeks in the treatment for bone and joint infection, as assessed by definitive treatment failure within one year of randomisation. These findings challenge the current standard of care and provide an opportunity to realise significant benefits for patients, antimicrobial stewardship and the health economy. Funding. The OVIVA study was funded by the National Institute for Health Research Health Technology Assessment programme (Project number 11/36/29)

Aim. Tedizolid is an oxazolidinone antibiotic that: (i) is recommended at the dose of 200 once daily in patients with skin and soft tissue infection; (ii) seems to have a better long-term hematological and neurological safety profile in comparison with linezolid; (iii) remains active on multidrug-resistant (MDR) Gram-positive pathogens. Consequently, it might represent an option as suppressive antimicrobial treatment (SAT) in patients with complex implant-associated bone and joint infection (BJI) due to MDR Gram-positive pathogens. Method. We performed a cohort study (2017–2020) to evaluate the long-term safety of tedizolid (200mg qd) as SAT in patients with implant-associated BJI. In all cases, the use of tedizolid was validated as the last oral treatment option during multidisciplinar meetings in a reference center for the management of BJI. Serious adverse events, any reason for discontinuation, and standard biological data, were prospectively collected. Results. Seventeen patients (13 males; median age 73 years) received tedizolid as SAT for late complex prosthetic-joint infections (n=16) or osteosynthesis (n=1). Pathogens were MDR coagulase negative staphylococci (16 patients), Corynebacterium striatrum (2 patients), Enterococcus faecium (1 patient) and/or S. aureus (1 patient). Tedizolid was always started after a primary treatment (median duration of intravenous 47 days; followed by linezolid in 12 patients including 9 who experienced linezolid-induced serious adverse event) that followed a surgery, mainly debridement and implant retention (13 patients). Median duration of tedizolid was 6 months (min, 1 month; max, 31 months). The only reason for discontinuation was a failure of the conservative strategy that occurred in four patients (17%) during the follow-up. No patients developed a serious adverse event, or a discontinuation of tedizolid due to an adverse event. Anemia was observed in two patients, who had already other known cause of anemia (chronic leukemia and oesophageal varices); stable thrombopenia was observed in a cirrhotic patient (80 G/L, stable during the treatment course of 12 months); and a transient mild neutropenia (1.4 G/L) was observed in another patient (Figure). No neurological adverse event was observed. Conclusions. Tedizolid seems to be a safe option as SAT in patients with complex implantassociated BJI due MDR Gram-positive pathogens. For any tables or figures, please contact the authors directly

Aim. Bone and joint infections (BJI) need frequently prolonged antibiotic treatment at high dosage for a total of 6 or 12 weeks depending the type of infection. Impact of such prolonged antibiotic exposure on the gut microbiota has never been assessed. Method. We performed a national multicentric prospective study of patients with BJI to monitor the gut microbiota dynamic all along antimicrobial treatment. Clinical data and stool collection were performed at the baseline visit (B) within 24h before starting antibiotics, at the end of the treatment (EOT) and 2 weeks after antibiotic withdrawal during a follow-up visit (FU). Microbiota composition was determined by shotgun metagenomic sequencing. Biological markers of gut permeability and inflammation were monitored at each time point. Results. Sixty-two patients were enrolled: 27 native BJI, 14 osteosynthesis-related BJI and 21 prosthetic joint infections (PJI). At EOT there was a significant loss of alpha-diversity that recovered at FU in patients with native BJI and PJI but not in patients with osteosynthesis-related BJI (p<0.05, Wilcoxon test). At EOT, we observed an increase of Proteobacteria and Bacteroidetes that partially recovered at FU. Principal Component Analysis (PCoA) of the Bray Curtis distance, showed a significant change of the gut microbiota at the end of treatment compared to baseline (p<0.01, PERMANOVA) that only partially recover at FU. The taxonomic analysis showed that microbiota composition at FU does not differ significantly at the genus level when comparing patients treated for 6 weeks to patients treated for 12 weeks. No particular antibiotic (especially fluoroquinolones) was associated with a lower Shannon index or distinct dynamic of recovery at the end of treatment. PCoA analysis of the Bray Curtis distance shows that patients with elevated plasma level of CRP (≥5mg/L) at EOT had a distinct gut microbial composition compared to others. Conclusions. In patients with BJI, antibiotics altered the gut microbiota diversity and composition with only partial recovery 2 weeks after antibiotic withdrawal, independently on the duration of the therapy and on the type of the antibiotic used. Elevated CRP at EOT might reflect persistent alteration of the gut microbiota. Assessment of long-term impact after the end of treatment is on-going

Aim. Synovial fluid investigation is the best alternative to diagnose prosthetic joint infection (PJI) before adequate microbiological/histology sampling during revision surgery. Although accurate preoperative diagnosis is certainly recommended, puncturing every patient before revision arthroplasty raises concerns about safety and feasibility issues especially in difficult to access joint (e.g., hip), that often require OR time and fluoroscopy/ultrasound guidance. Currently there is no clear guidelines regarding optimal indications to perform preoperative joint aspiration to diagnose PJI before revision surgery. The main goal of this study is to determine the accuracy of our institutional criteria using the new European Bone and Joint Infection Society (EBJIS) PJI definition. Method. We retrospectively evaluated every single- or first-stage for presumed aseptic or known infected revision total hip/knee arthroplasty procedures between 2013–2020. Preoperative clinical and laboratory features were systematically scrutinized. Cases with insufficient information for accurate final PJI diagnosis (i.e., no perioperative synovial fluid examination or no multiple cultures including sonication of removed implant) were excluded. Preoperative joint aspiration is recommended in our institution if any of the following criteria are met: 1) elevated CRP and/or ESR; 2) early failure (<2 years) or repeat failure; 3) high clinical suspicion/risk factors are present. Performance of such criteria were compared against final postoperative EBJIS definition PJI diagnosis. Results. A total of 364 revision THAs or TKAs were performed during the study period. After excluding 258 cases with insufficient information, a total of 106 patients were ultimately included. 38 (35,8 %) were classified as confirmed infections, 10 (9.4 %) as likely infected and 58 (54.7%) as infection unlikely. Of those, 37 confirmed infection cases, 9 likely infected cases and 32 infection unlikely cases did have indication for preoperative synovial fluid collection before revision surgery. Institutional criteria showed 95.8 % Sensitivity, 44.83 % Specificity, 92.9 % Negative Predictive Value (NPV) and 59 % Positive Predictive Value (PPV). Conclusions. Sensitivity and NPV of the aforementioned institutional criteria are very high even with the use of the more sensitive EBJIS PJI definition. As such they seem to be a valid alternative in selecting patients that should be punctured before revision arthroplasty. They identify the vast majority of infected patients while saving a significant number of patients from unnecessary procedures

Background. Antibiotic-loaded cement has been used over decades as a local antibiotic delivery for the treatment of bone and joint infections. However, there were some disadvantages such as unpredictable elution, insufficient local concentration and reduced mechanical strength. We developed hydrophilized bone cement and investigated whether it can improve consistent antibiotic release for extended periods to be effective in eradicating joint infection without any changes of mechanical strength. Methods. The experiments consists of preparation of the hydrophilized, vancomycin-loaded bone cement, In vitro test including drug release behavior, mechanical properties by compression test, cytotoxicity, antibacterial effect and animal study. In animal study, Antibiotic cement rod was implanted in the femur of rat osteomyelitis model. Sign of infections were assessed by gross observation, Micro CT and blood analysis at indicated period. Results. The hydrophilized Vancomycin-loaded bone cements showed that continuous release of Vancomycin even over 6 weeks in the drug release test, sufficient mechanical strengths in the compression test and also better anti-bacterial effect compared to other commercially available bone cement. The animal study demonstrated that it has superior inhibition of bacterial proliferation according to imaging and blood analysis compared to control group. Conclusion:. As a results from both in vitro test and animal study, hydrophilized antibiotic bone cement may provide favorable environment to control bone and joint infection by continuous antibiotic release for extended period

Background/objective: Although several prospective trials have shown the efficacy of sequential intravenous followed by oral antimicrobial regimen in treatment of bone and joint infections, considerable uncertainty exists about ideal antibiotic regimen and optimal duration of antibiotic therapy. The aim of this study was to demonstrate that short course antibiotic therapy combined with surgical drainage and followed by oral antibiotic therapy is quite adequate and suggested a scoring system as a comfortable and reliable tool to adjust the route of drug administration. Methods: Thirty-three cases of acute hematogenous bone or joint infection were randomly treated with short term (7 days for joint infection, l0 days for bone infection) or a long-term (14 days and 21 days, respectively) intravenous antibiotics after surgical drainage. The treatment outcome was measured through a detailed scoring system that included the ability to eradicate infection, the functional status of the limb, and the radiological appearance of the bone and joint. Criteria for discontinuation of parenteral antibiotic Scoring criteriapoints. Clinical evaluation. A: improved active motion of the joint: l. B: Painless active motion of the joint: 2. C: improvement in A & B:3. Radiological findings. A: progressive osteolysis ormultifocal involvement: 0. B: absence of the above findings*: 1. Laboratory evaluation. A: drop of 50.00/mm3 in WBC count or return to normal range (5.000–10.000 /mni3): 0.5. B: drop in ESR of 30 mm/hr or return to level of 30 mm/hr or less: 0.5. Total score: 5. *Pure periosteal elevation received a score of 1. Patients with a score > or equal to 4 would be switched to oral antibiotic. Results: The average follow up was 19 months. The scoring system had the following results: Infection was eradicated in both groups. Radiological scoring for septic arthritis was full for both groups and had a non-significant difference P> 0.05 between the 2 groups for osteomyelitis. The mean functional scoring between the short-term group and long-term group were similar P> 0.05. Overall, excellent or good results were achieved in both groups. No fair or poor results were observed. The average hospital cost for a patient in long-term group was twice that of a patient in short-term group. Conclusion: It is concluded that for bone or joint infection in children who have received appropriate and early surgical treatment, intravenous antibiotics given for 7 days in joint infections and 10 days in bone infections, followed by 4 weeks of oral antibiotics, is an adequate treatment. A decision on prolonging the duration of parenteral antibiotics should be based on a combination of clear clinical, laboratory, and radiographic criteria, such us the scoring system presented in this article

Introduction. Microbiological diagnosis of bone and joint infections (BJIs) currently relies on standard cultures which are time consuming and lack sensitivity. Various molecular approaches have been described and allowed improvement of BJI diagnosis. This study evaluated for the first time the performance of a DNA microarray-based assay (Prove-it™ Sepsis assay, PISA) for the rapid (<6 hours) detection and identification of 50 different species involved in BJI directly from clinical samples. Material and methods. We retrospectively selected 130 bone and joint samples (67 synovial fluids and 63 bone biopsies) including 114 positive and 16 negative samples. The microbiological diagnosis had been previously established either by culture(C+, n=53) or by PCR16S and sequencing when culture was negative (C-/PCR+). The positive samples were selected to match the species targeted on the DNA microarray. DNA extraction was performed before proceeding to PISA amplification and hybridization on every selected sample. Results. Among the 16 negative samples, one was detected positive with S. epidermidis by PISA, result that was secondarily confirmed using specific PCR. Among the 114 positive samples, 62.3% were positive using PISA with highly concordant identification compared to culture and PCR16S/sequencing results. Forty-three samples (37.7%) remained negative, illustrating a defect of sensitivity. However, PISA accurately detected methicillin resistance not only among the 16 C+/PISA+ Staphylococcus species (n=5) but also among the 28 C-/PCR16S+ Staphylococcus species (n=12) offering crucial rapid information to adapt the treatment of staphylococcal BJIs. Seven polymicrobial samples were also identified without extensive experiments. Discussion – Conclusion. Even if the sensitivity deserves to be improved by optimizing DNA extraction and investigating on human DNA interference, these preliminary promising results highlight that this new and simple microarray method could be in the future an alternative to conventional PCR16S for the diagnosis of BJI

Aim. To demonstrate the use of indium-111 white-cell labelled SPECT CT (In111-WC-SPECT-CT) in bone infection. Method. This novel imaging modality is useful in bone infection. We present three cases of complex osteomyelitis to illustrate this. All were imaged with conventional modalities, but conclusive diagnosis could not be achieved. In111-WC-SPECT-CT was used to provide the definitive imaging that allowed successful treatment. Results. Case 1- A 29 y/o Male with spina bifida presented with chronic calcaneal osteomyelitis. Previous treatment included debridement, but recurrent infection ensued. MRI showed widespread changes consistent with infection throughout the calcaneus and a below knee amputation was planned. In111-WC-SPECT-CT (Figure 1) showed a distinct localised nidus of infection. A targeted sequestrectomy was performed and the patient has been infection free for four years. He was spared the amputation. Case-2- A 73 y/o male presented with a radiation induced colo-cutaneous fistula and pelvic chronic osteomyelitis. Surgical treatment included multiple debridements and sequestrectomy. He re-presented pain with pain in his pelvis six months later. MRI was performed and oedema seen in the bone. This was presumed to be infection and further surgery was planned. An In111-WC-SPECT-CT was then performed and confirmed no residual bone infection. The patient was spared surgery. Case-3- A 38 y/o female was involved in an RTA 6 months prior to presentation. She underwent fixation of her tibia with skin grafting for an open fracture. There was clinical suspicion of deep infection. The metalwork made MRI difficult to interpret. An In111-WCC-SPECT-CT confirmed infection around the metal screw and this evidence instigated a prolonged course of antibiotics to suppress the infection. The screw will be removed after the fracture heals. Conclusions. In-111-WC-SPECT-CT is an emerging imaging modality. We present three cases of complex bone and joint infection; where this imaging has altered the course of treatment

Bone and joint infections are not only common but their management can be technically complex. They carry significant healthcare costs and are a daunting experience for patients [1]. Frequently, multiple operations are required in order to treat the infection. Each surgical intervention usually results in greater bone loss, worsening skin and soft tissue scarring and increasingly diverse and resistant micro- organisms [2]. Specialist bone infection units involving highly integrated orthopaedic and plastic surgery, as well as infection physicians, may improve patient outcomes [3–4]. However, it is difficult to determine the hierarchy of factors contributing to outcome of treatment. This problem is confounded by a lack of structured, prospective data collection in many units around the world. In 2014, we designed a modular database which allows collection of patients’ details, components of the disease, the treatment, microbiology, histology, clinical outcome and patient-reported outcome measures (PROMS). The registry was implemented in November 2014 and has already demonstrated its function as a Hospital-wide service evaluation tool. Over 200 patients have been referred to the unit and their baseline demographic information registered. Their progress through the bone infection unit patient pathway is prospectively monitored with use of the registry and data collection ongoing. We aim to present the preliminary clinical outcomes of these 200 patients including surgical procedures performed, key microbiology results, antibiotic treatment regimens and patient reported outcomes. Our goal is to demonstrate that a bone infection registry is an integral part of infection management clinical practice. It can be used for designing service provision, assist in allocating healthcare resources and expand the evidence base for specialist bone infection units in managing complex orthopaedic infections

Aim

Antibiotic-eluting calcium compounds can be used to deliver antibiotics in the management of prosthetic joint infection (PJI). Described omplications include wound drainage, heterotopic ossification(HO) as well as hypercalcaemia which is potentially life threatening.

The aim of this study is to assess the incidence of hypercalcaemia and other complications between two calcium based antibiotic delivery systems.

Aim

Accurate diagnosis is key in correctly managing prosthetic joint infection (PJI). Our aim is to compare the preoperative performance of three PJI definitions comparing it to definitive postoperative classification.

Aim

Leading etiology of Bone and Join infections (BJI), Staphylococcus aureus (SA) is responsible for difficult-to-treat infections mainly because of three persistence factors: (i) biofilm formation, (ii) persistence within bone cells and (iii) switch to the small colony variant (SCV) phenotype. The impact of rifampin on these mechanisms gave it a prominent place in orthopedic device-associated BJI. However, resistance emergence, intolerance and drug interactions cause significant concerns. In this context, other rifamycins – namely rifapentine and rifabutin – have poorly been evaluated, particularly toward their ability to eradicate biofilm-embedded and intracellular reservoirs of SA.

Background. With promising antibiofilm properties, rifampicin is considered as a cornerstone in the complementary treatment of bone and joint infections. But, achieving an adequate concentration of rifampicin long-term in bone tissue is a challenge. Long-term systemic administration also comes with concomitant side effects. Thus, local delivery of rifampicin in a carrier to ensure the high local concentration of antibiotic in surgical site after intervention due to infection could be a valuable alternative. However, an ideal platform for local delivery of rifampicin is still lacking. A calcium sulphate/hydroxyapatite (CaS/HA) (Cerament, Bonesupport AB, Sweden) biomaterial was used as a local delivery platform. Here we aimed 1) to evaluate the injectability of CaS/HA hand-mixed with rifampicin at various concentrations up to maximum one daily dose used systemically in clinical practice 2) to test a clinically used and commercially available mixing device containing the biphasic ceramic with rifampicin. Materials & Methods. Three different concentrations (100 mg, 300 mg and 600 mg) of rifampicin powder (Rifampicin Ebb, Sanofi S.P.A, Italy) diluted in 5 mL of mixing solution (C-TRU, Bonesupport AB, Sweden) were used. Rifampicin solution was mixed to the CaS/HA powder and the injectability of the CaS/HA plus rifampicin composite was evaluated by extruding 250 µL of paste manually through a graduated 1 mL syringe connected to an 18G needle (Ø=1.2 mm, L=4 cm). Mixing was done with a spatula for 30 s at 22°C ±1°C. Total weight of the paste before and after extrusion were measured. To normalize the amount of composite that remained in the needle and syringe tip after injection, the mean of the paste extruded from the syringe at 3 min was calculated for the tested concentrations (normalized value). Injectability (%) was calculated by dividing the weight of the paste extruded from the syringe with normalized value. Each test was repeated for three times at various time points (3, 5, 7 and 9 min). Additionally, 300 mg rifampicin was chosen to mix with the CaS/HA in a commercially available mixing system, which is used clinically. Results. All three combinations of CaS/HA plus rifampicin (100 mg, 300 mg & 600 mg) could be completely extruded from 1 mL syringes at 3 min. At 5 min, 100 mg & 300 mg could still be injected, whereas 600 mg was uninjectable or solidified. At 7 min, rifampicin 100 mg & 300 mg showed 34% and 11% of injectability respectively. At 9 min, no injectability was observed. The material was completely set within 15 minutes with all concentrations. With commercial mixing system, at the recommended injection time of 4 min, 78% of the CaS/HA plus rifampicin (300 mg) composite could be injected. Conclusions. The injectability was reduced with the increasing concentration of rifampicin. CaS/HA plus rifampicin (100 mg and/or 300 mg) could be used by hand mixing and transferred to a syringe or by using an available mixing system containing the ceramic. For higher concentrations of rifampicin, the rheological properties of the ceramics have to be modified for injectability

Aims. Calcium sulphate (CaSO. 4. ) is a resorbable material that can be used simultaneously as filler of a dead space and as a carrier for the local application of antibiotics. Our aim was to describe the systemic exposure and the wound fluid concentrations of vancomycin in patients treated with vancomycin-loaded CaSO. 4. as an adjunct to the routine therapy of bone and joint infections. Patients and Methods. A total of 680 post-operative blood and 233 wound fluid samples were available for analysis from 94 implantations performed in 87 patients for various infective indications. Up to 6 g of vancomycin were used. Non-compartmental pharmacokinetic analysis was performed on the data from 37 patients treated for an infection of the hip. Results. The overall systemic exposure remained within a safe range, even in patients with post-operative renal failure, none requiring removal of the pellets. Local concentrations were approximately ten times higher than with polymethylmethacrylate (PMMA) as a carrier, but remained below reported cell toxicity thresholds. Decreasing concentrations in wound fluid were observed over several weeks, but remained above the common minimum inhibitory concentrations for Staphylococcus up to three months post-operatively. . Conclusion. This study provides the first pharmacokinetic description of the local application of vancomycin with CaSO. 4. as a carrier, documenting slow release, systemic safety and a release profile far more interesting than from PMMA. In particular, considering in vitro data, concentrations of vancomycin active against staphylococcal biofilm were seen for several weeks. Cite this article: Bone Joint J 2017;99-B:1537–44

Paediatric bone and joint infections remain common in low- and middle-income countries (LMICs). We aimed to determine the complication rate and incidence of disseminated infection in paediatric bone and joint infections in an LMIC setting. Secondly, we aimed to elucidate factors associated with complications and disseminated disease. We retrospectively reviewed our database for children that presented with bone and joint infections between September 2015 and March 2019. Data were extracted to identify factors that were associated with development of complications and disseminated infection. We analysed 49 children. The median age at presentation was 6 years (range 1 month to 12 years). Locally advanced disease was present in 13 children (27%). The remaining 36 children were evenly divided (18/49 each, 37%) between isolated AHOM and SA, respectively. Disseminated disease was present in 16 children (33%) and was associated with locally advanced disease, an increase in number of surgeries and an increased length of stay. Twenty-six complications were documented in 22 (45%) children. Chronic osteomyelitis developed in 15/49 (31%) cases, growth arrest in 5/49 (10%), and pathological fracture, DVT and septic shock in 2/49 (4%) each. Complicated disease was associated with locally advanced disease, a higher number of surgeries, disseminated disease and an increased length of stay. Sixty five percent of cases cultured Staphylococcus aureus, while 25% (12/49) were culture negative. The median time from admission to surgery was one day, and the median time from onset of symptoms to surgery was seven days. We found a high complication rate. One third of patients had locally advanced disease, and this was associated with the development of complications and disseminated disease. Further studies are needed to be able to predict which children will have poor outcomes

Aim. To evaluate whether sonication of implant material and subsequent culturing add clinical relevance to culturing of tissue biopsies for improved antibiotic treatment in treatment of bone and joint infection. Method. A retrospective examination of patients’ charts and microbiological analyses in patients who had explanted material (plates, screws, k-wires and prostheses) send for sonication between December 2020 and April 2022. Results. 77/143 (54 %) patients had complete agreement between the cultures from tissue biopsies and sonication fluid. 66/143 (46 %) patients had partial or no agreement between the cultures from tissue biopsies and sonication fluid. Of the 66 patients, 31 (47 %) had a culture positive sonication fluid and tissue biopsies that were positive with one or more bacterial isolates. 26/66 (39 %) patients had a culture positive sonication fluid and tissue biopsies that were negative. 9/66 (14 %) patients had negative sonication fluid and positive tissue biopsies. Of the 26 patients with culture positive sonication fluid and culture negative tissue biopsies, virulent bacteria were found in 5 (19 %) patients, making the diagnosis and treatment of infection straight forward. The remaining 21 (81 %) patients had C. acnes, S. epidermidis and CoNS in the sonication fluid, which made the diagnosis less evident but none the less gave the clinician a relevant treatment option. Conclusion. In this study a high concordance was found between cultures from tissue biopsies and sonication fluid. Additionally, in a small group of patients with culture negative tissue biopsy, the culture of sonication fluid was essential to the identification infections agent. This indicates that culture of sonication fluid is an important diagnostic tool in bone and joint infection, especially in the absence of positive tissue cultures

Aims. This study evaluated the definitions developed by the European Bone and Joint Infection Society (EBJIS) 2021, the International Consensus Meeting (ICM) 2018, and the Infectious Diseases Society of America (IDSA) 2013, for the diagnosis of periprosthetic joint infection (PJI). Methods. In this single-centre, retrospective analysis of prospectively collected data, patients with an indicated revision surgery after a total hip or knee arthroplasty were included between 2015 and 2020. A standardized diagnostic workup was performed, identifying the components of the EBJIS, ICM, and IDSA criteria in each patient. Results. Of 206 included patients, 101 (49%) were diagnosed with PJI with the EBJIS definition. IDSA and ICM diagnosed 99 (48%) and 86 (42%) as infected, respectively. A total of 84 cases (41%) had an infection based on all three criteria. In 15 cases (n = 15/206; 7%), PJI was present when applying only the IDSA and EBJIS criteria. No infection was detected by one definition alone. Inconclusive diagnoses occurred more frequently with the ICM criteria (n = 30/206; 15%) compared to EBJIS (likely infections: n = 16/206; 8%) (p = 0.029). A better preoperative performance of the EBJIS definition was seen compared with the ICM and IDSA definitions (p < 0.001). Conclusion. The novel EBJIS definition identified all PJIs diagnosed by any other criteria. Use of the EBJIS definition significantly reduced the number of uncertain diagnoses, allowing easier clinical decision-making. Cite this article: Bone Joint Res 2022;11(9):608–618

Aim. Local antibiotic treatment for bone and joint infections offers direct delivery of high concentrations of antibiotics with reduced systemic exposure and favourable safety profile. However, the possibility of prolonged release of antibiotics at sub-therapeutic levels creates concern about the possible development of antimicrobial resistance. We investigated patients with recurrent bone and joint infection for evidence of antimicrobial resistance emerging from the use of local antibiotics. Method. 125 patients with recurrent infection (prosthetic joint infection, fracture related infection and osteomyelitis) in the UK between 2007 and 2021 were identified. Electronic patient records (including operative notes, pathology results and prescriptions) were reviewed to extract site of infection, date of surgery, the use of local antibiotics, culture results, empiric and definitive antibiotic therapy. All antibiotic sensitivity results were recorded as sensitive, intermediate or resistant according to contemporary guidelines (BSAC and EUCAST). Results. Local antibiotics were used in 74/125 (59.2%) of patients. Agents used were Gentamicin 53/125 (42.4%), Tobramycin 18/125 (14.4%), and vancomycin in 19/125 (15.2%). Combined gentamicin and vancomycin usage was seen in 16/125 patients (12.8%). Gentamicin non-sensitivity was common in this cohort with frequent aminoglycoside use. At index procedure, a Gentamicin non-sensitive organism was cultured in 51/125 patients (40.8%). At re-operation this proportion was lower: 40/125 (32%). There was no statistically significant difference in the rate of Gentamicin resistance at reoperation comparing patients who previously received local aminoglycosides with those who had not (21/71, 29.8% vs 19/54, 35.2% p=0.6, chi-squared test). In 48/125 (38.4%) of patients, the same species was isolated during the index and recurrence surgery. We identified 7 cases with new aminoglycoside resistance arising at the second procedure. In 2/7 – S. aureus and E. faecalis - aminoglycoside resistance was the only change in antimicrobial sensitivity. In 5/7, there were at least 2 additional changes in observed antimicrobial sensitivity. 3/74 (4%) of cases who initially received local aminoglycoside cultured organisms with aminoglycoside resistance at recurrence. 4/51 (7.8%) of those who did not receive local or systemic aminoglycoside at index surgery cultured resistant organisms (chi square 0.82; p=0.365). Conclusions. As a group, patients whose treatment for orthopaedic infection included local antibiotics did not exhibit higher rates of specific antimicrobial resistance compared with those not treated with local antibiotics. However we did identify cases where Gram positive bacteria developed aminoglycoside resistance regardless of their initial antimicrobial therapy. This should be considered in antimicrobial choice during surgery for recurrence

Aims. Accurate diagnosis of chronic periprosthetic joint infection (PJI) presents a significant challenge for hip surgeons. Preoperative diagnosis is not always easy to establish, making the intraoperative decision-making process crucial in deciding between one- and two-stage revision total hip arthroplasty (THA). Calprotectin is a promising point-of-care novel biomarker that has displayed high accuracy in detecting PJI. We aimed to evaluate the utility of intraoperative calprotectin lateral flow immunoassay (LFI) in THA patients with suspected chronic PJI. Methods. The study included 48 THAs in 48 patients with a clinical suspicion of PJI, but who did not meet European Bone and Joint Infection Society (EBJIS) PJI criteria preoperatively, out of 105 patients undergoing revision THA at our institution for possible PJI between November 2020 and December 2022. Intraoperatively, synovial fluid calprotectin was measured with LFI. Cases with calprotectin levels ≥ 50 mg/l were considered infected and treated with two-stage revision THA; in negative cases, one-stage revision was performed. At least five tissue cultures were obtained; the implants removed were sent for sonication. Results. Calprotectin was positive (≥ 50 mg/l) in 27 cases; out of these, 25 had positive tissue cultures and/or sonication. Calprotectin was negative in 21 cases. There was one false negative case, which had positive tissue cultures. Calprotectin showed an area under the curve of 0.917, sensitivity of 96.2%, specificity of 90.9%, positive predictive value of 92.6%, negative predictive value of 95.2%, positive likelihood ratio of 10.6, and negative likelihood ratio of 0.04. Overall, 45/48 patients were correctly diagnosed and treated by our algorithm, which included intraoperative calprotectin measurement. This yielded a 93.8% concordance with postoperatively assessed EBJIS criteria. Conclusion. Calprotectin can be a valuable tool in facilitating the intraoperative decision-making process for cases in which chronic PJI is suspected and diagnosis cannot be established preoperatively. Cite this article: Bone Joint J 2024;106-B(5 Supple B):118–124

Aims. 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). Methods. In this retrospective diagnostic study, patients undergoing revision surgery after total hip or knee arthroplasty (n = 119) between January 2015 and July 2018 were included. Multiple specimens of the periprosthetic membrane and pseudocapsule were obtained for histopathological analysis at revision arthroplasty. Based on the Infectious Diseases Society of America (IDSA) 2013 criteria, the International Consensus Meeting (ICM) 2018 criteria, and the European Bone and Joint Infection Society (EBJIS) 2021 criteria, PJI was defined. Using a mixed effects logistic regression model, the sensitivity and specificity of the histological diagnosis were calculated. The optimal number of periprosthetic tissue specimens for histopathological analysis was determined by applying the Youden index. Results. Based on the EBJIS criteria (excluding histology), 46 (39%) patients were classified as infected. Four to six specimens showed the highest Youden index (four specimens: 0.631; five: 0.634; six: 0.632). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of five tissue specimens were 76.5% (95% confidence interval (CI) 67.6 to 81.4), 86.8% (95% CI 81.3 to 93.5), 66.0% (95% CI 53.2 to 78.7), and 84.3% (95% CI 79.4 to 89.3), respectively. The area under the curve (AUC) was calculated with 0.81 (as a function of the number of tissue specimens). Applying the ICM and IDSA criteria (excluding histology), 40 (34%) and 32 (27%) patients were categorized as septic. Three to five specimens had the highest Youden index (ICM 3: 0.648; 4: 0.651; 5: 0.649) (IDSA 3: 0.627; 4: 0.629; 5: 0.625). Conclusion. Three to six tissue specimens of the periprosthetic membrane and pseudocapsule should be collected at revision arthroplasty and analyzed by a pathologist experienced and skilled in interpreting periprosthetic tissue. Cite this article: Bone Joint J 2023;105-B(2):158–165

Aims. Serum inflammatory parameters are widely used to aid in diagnosing a periprosthetic joint infection (PJI). Due to their limited performances in the literature, novel and more accurate biomarkers are needed. Serum albumin-to-globulin ratio (AGR) and serum CRP-to-albumin ratio (CAR) have previously been proposed as potential new parameters, but results were mixed. The aim of this study was to assess the diagnostic accuracy of AGR and CAR in diagnosing PJI and to compare them to the established and widely used marker CRP. Methods. From 2015 to 2022, a consecutive series of 275 cases of revision total hip (n = 129) and knee arthroplasty (n = 146) were included in this retrospective cohort study. Based on the 2021 European Bone and Joint Infection Society (EBJIS) definition, 144 arthroplasties were classified as septic. Using receiver operating characteristic curve (ROC) analysis, the ideal thresholds and diagnostic performances were calculated. The areas under the curve (AUCs) were compared using the z-test. Results. AGR, CAR, and CRP were associated with PJI (p < 0.001). Sensitivities were 62.5% (95% CI 54.3 to 70.0), 73.6% (95% CI 65.8 to 80.1), and 71.5% (95% CI 63.6 to 78.3), respectively. Specificities were calculated with 84.7% (95% CI 77.5 to 89.9), 86.3% (95% CI 79.2 to 91.2), and 87.8% (95% CI 80.9 to 92.4), respectively. The AUC of CRP (0.797 (95% CI 0.750 to 0.843)) was significantly higher than the AUC of AGR (0.736 (95% CI 0.686 to 0.786), p < 0.001), and similar to AUC of CAR (0.799 (95% CI 0.753 to 0.846), p = 0.832). Decreased sensitivities were observed in PJIs caused by low-virulence organisms (AGR: 60%, CAR: 78%) compared to high-virulence pathogens (AGR: 80%, p = 0.042; CAR: 88%, p = 0.158). Higher sensitivities were seen in acute haematogenous (AGR: 83%, CAR: 96%) compared to chronic PJIs (AGR: 54%, p = 0.001; CAR: 65%, p < 0.001). Conclusion. Serum AGR and CAR showed limited diagnostic accuracy (especially in low-grade and chronic infections) and did not outperform the established marker CRP in our study. Hence, neither parameter can be recommended as an additional tool for diagnosing PJI. Cite this article: Bone Joint Res 2024;13(8):372–382

Aims. 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. Methods. Episodes of knee or hip PJI (defined by the European Bone and Joint Infection Society criteria) treated at our institution between January 2015 and October 2020 were included in a retrospective PJI cohort. Episodes with a follow-up of > one year were stratified by route of infection into haematogenous and non-haematogenous PJI. Probability of failure-free survival was estimated using the Kaplan-Meier method, and compared between groups using log-rank test. Univariate and multivariate analysis was applied to assess risk factors for failure. Results. A total of 305 PJI episodes (174 hips, 131 knees) were allocated to the haematogenous (n = 146) or the non-haematogenous group (n = 159). Among monomicrobial infections, Staphylococcus aureus was the dominant pathogen in haematogenous PJI (76/140, 54%) and coagulase-negative staphylococci in non-haematogenous PJI (57/133, 43%). In both groups, multi-stage exchange (n = 55 (38%) in haematogenous and n = 73 (46%) in non-haematogenous PJI) and prosthesis retention (n = 70 (48%) in haematogenous and n = 48 (30%) in non-haematogenous PJI) were the most common surgical strategies. Median duration of antimicrobial treatment was 13.5 weeks (range, 0.5 to 218 weeks) and similar in both groups. After six years of follow-up, the probability of failure-free survival was significantly lower in haematogenous compared to non-haematogenous PJI (55% vs 74%; p = 0.021). Infection-related mortality was significantly higher in haematogenous than non-haematogenous PJI (7% vs 0% episodes; p = 0.001). Pathogenesis of failure was similar in both groups. Retention of the prosthesis was the only independent risk factor for failure in multivariate analysis in both groups. Conclusion. Treatment failure was significantly higher in haematogenous compared to non-haematogenous PJI. Retention of the prosthesis was the only independent risk factor for failure in both groups. Cite this article: Bone Joint J 2023;105-B(12):1294–1302

Aims. This study aims to assess the relationship between history of pseudotumour formation secondary to metal-on-metal (MoM) implants and periprosthetic joint infection (PJI) rate, as well as establish ESR and CRP thresholds that are suggestive of infection in these patients. We hypothesized that patients with a pseudotumour were at increased risk of infection. Methods. A total of 1,171 total hip arthroplasty (THA) patients with MoM articulations from August 2000 to March 2014 were retrospectively identified. Of those, 328 patients underwent metal artefact reduction sequence MRI and had minimum two years’ clinical follow-up, and met our inclusion criteria. Data collected included demographic details, surgical indication, laterality, implants used, history of pseudotumour, and their corresponding preoperative ESR (mm/hr) and CRP (mg/dl) levels. Multivariate logistic regression modelling was used to evaluate PJI and history of pseudotumour, and receiver operating characteristic curves were created to assess the diagnostic capabilities of ESR and CRP to determine the presence of infection in patients undergoing revision surgery. Results. The rate of PJI for all identified MoM THAs was 3.5% (41/1,171), with a mean follow-up of 10.9 years (2.0 to 20.4). Of the patients included in the final cohort, 8.2% (27/328) had PJI, with a mean follow-up of 12.2 years (2.3 to 20.4). Among this cohort, 31.1% (102/328) had a history of pseudotumour. The rate of PJI in these patients was 14.7% (15/102), which was greater than those without pseudotumour, 5.3% (12/226) (p = 0.008). Additionally, logistic regression analysis showed an association between history of pseudotumour and PJI (odds ratio 4.36 (95% confidence interval 1.77 to 11.3); p = 0.002). Optimal diagnostic cutoffs for PJI in patients with history of pseudotumour versus those without were 33.1 mm/hr and 24.5 mm/hr for ESR and 7.37 mg/dl and 1.88 mg/dl for CRP, respectively. Conclusion. Patients with history of pseudotumour secondary to MoM THA had a higher likelihood of infection than those without. While suspicion of infection should be high for these patients, ESR and CRP cutoffs published by the European Bone and Joint Infection Society may not be appropriate for patients with a history of pseudotumour, as ESR and CRP levels suggestive of PJI are likely to be higher than for those without a pseudotumour. Additional investigation, such as aspiration, is highly recommended for these patients unless clinical suspicion and laboratory markers are low. Cite this article: Bone Joint J 2024;106-B(6):555–564

Aims. The number of revision arthroplasties being performed in the elderly is expected to rise, including revision for infection. The primary aim of this study was to measure the treatment success rate for octogenarians undergoing revision total hip arthroplasty (THA) for periprosthetic joint infection (PJI) compared to a younger cohort. Secondary outcomes were complications and mortality. Methods. Patients undergoing one- or two-stage revision of a primary THA for PJI between January 2008 and January 2021 were identified. Age, sex, BMI, American Society of Anesthesiologists grade, Charlson Comorbidity Index (CCI), McPherson systemic host grade, and causative organism were collated for all patients. PJI was classified as ‘confirmed’, ‘likely’, or ‘unlikely’ according to the 2021 European Bone and Joint Infection Society criteria. Primary outcomes were complications, reoperation, re-revision, and successful treatment of PJI. A total of 37 patients aged 80 years or older and 120 patients aged under 80 years were identified. The octogenarian group had a significantly lower BMI and significantly higher CCI and McPherson systemic host grades compared to the younger cohort. Results. The majority of patients were planned to undergo two-stage revision, although a significantly higher proportion of the octogenarians did not proceed with the second stage (38.7% (n = 12) vs 14.8% (n = 16); p = 0.003). Although there was some evidence of a lower complication rate in the younger cohort, this did not reach statistical significance (p = 0.065). No significant difference in reoperation (21.6% (n = 8) vs 25.0% (n = 30); p = 0.675) or re-revision rate (8.1% (n = 3) vs 16.7% (n = 20); p = 0.288) was identified between the groups. There was no difference in treatment success between groups (octogenarian 89.2% (n = 33) vs control 82.5% (n = 99); p = 0.444). Conclusion. When compared to a younger cohort, octogenarians did not show a significant difference in complication, re-revision, or treatment success rates. However, given they are less likely to be eligible to proceed with second stage revision, consideration should be given to either single-stage revision or use of an articulated spacer to maximize functional outcomes. Cite this article: Bone Joint J 2024;106-B(8):802–807

Aims. Periprosthetic joint infections (PJIs) and fracture-related infections (FRIs) are associated with a significant risk of adverse events. However, there is a paucity of data on cardiac complications following revision surgery for PJI and FRI and how they impact overall mortality. Therefore, this study aimed to investigate the risk of perioperative myocardial injury (PMI) and mortality in this patient cohort. Methods. We prospectively included consecutive patients at high cardiovascular risk (defined as age ≥ 45 years with pre-existing coronary, peripheral, or cerebrovascular artery disease, or any patient aged ≥ 65 years, plus a postoperative hospital stay of > 24 hours) undergoing septic or aseptic major orthopaedic surgery between July 2014 and October 2016. All patients received a systematic screening to reliably detect PMI, using serial measurements of high-sensitivity cardiac troponin T. All-cause mortality was assessed at one year. Multivariable logistic regression models were applied to compare incidence of PMI and mortality between patients undergoing septic revision surgery for PJI or FRI, and patients receiving aseptic major bone and joint surgery. Results. In total, 911 consecutive patients were included. The overall perioperative myocardial injury (PMI) rate was 15.4% (n = 140). Septic revision surgery for PJI was associated with a significantly higher PMI rate (43.8% (14/32) vs 14.5% (57/393); p = 0.001) and one-year mortality rate (18.6% (6/32) vs 7.4% (29/393); p = 0.038) compared to aseptic revision or primary arthroplasty. The association with PMI persisted in multivariable analysis with an adjusted odds ratio (aOR) of 4.7 (95% confidence interval (CI) 2.1 to 10.7; p < 0.001), but was not statistically significant for one-year mortality (aOR 1.9 (95% CI 0.7 to 5.4; p = 0.240). PMI rate (15.2% (5/33) vs 14.1% (64/453)) and one-year mortality (15.2% (5/33) vs 9.1% (41/453)) after FRI revision surgery were comparable to aseptic long-bone fracture surgery. Conclusion. Patients undergoing revision surgery for PJI were at a risk of PMI and death compared to those undergoing aseptic arthroplasty surgery. Screening for PMI and treatment in specialized multidisciplinary units should be considered in major bone and joint infections. Cite this article: Bone Joint J 2022;104-B(6):696–702

Aim. Multidisciplinary team (MDT) management of complex bone and joint infections (BJI) is increasingly implemented but studies evaluating this approach are scarce. We assessed the effectiveness of our MDT by analyzing the adherence to its treatment decisions. Method. A cohort study was conducted comprising patients with complex BJI of which the management was discussed during MDT meetings between 2015 and 2022 in a tertiary care academic hospital. Patient characteristics and MDT data were obtained from electronic patient records. Results. The analysis included 1321 MDT case decisions on 509 patients. During the study period, the number of patients discussed by the MDT increased from 2.7 to 5.5 per meeting. The percentage of discussed patients with BJI other than prosthetic joint infections (PJI) increased from 26% to 52%. The overall adherence rate to MDT decisions was 92.1%. Reasons for non-adherence were disagreement with the MDT whether cure was achieved or not (34%), new clinical information that was not available during the MDT meeting (12%), preference for suppressive antibiotic treatment over surgery (8%) or not recorded in the patient file (46%). Conclusions. Over the years, the MDT meeting content expanded from mainly PJI to all complex BJI. The high adherence rate to MDT decisions was indicative of an effective MDT. Analysis of adherence is a useful tool to evaluate an MDT and can be used to improve its quality. Different aspects of an MDT need to be evaluated to fully determine its impact and to help improve the care for patients with complex BJI

Aim. Debridement, antibiotics and implant retention (DAIR) are considered as an optimal curative treatment option for prosthetic joint infection (PJI) when the biofilm is still immature and radical debridement is achievable. There are two main groups of patients suitable for DAIR. Those with an early acute PJI and patients with acute hematogenous PJI. However, there is also a third group of early PJI resulting from a wound healing problem or leaking hematoma. These may be either high or low grade depending on the microorganisms that infected the artificial joint “per continuitatem”. Methods. We retrospectively analysed 100 successive DAIR procedures on prosthetic hip and knee joints performed between January 2010 and January 2022, from total of 21000 primary arthroplasties implanted within the same time period. We only included PJI in primary total replacements with no previous surgeries on the affected joint. Patients data (demographics, biochemical, microbiological, histopathological results, and outcomes) were collected from hospital bone and joint infection registry. The aim of surgery was radical debridement and the mobile parts exchange. The standardized antibiotic regime based on antibiofilm antibiotics. Results. The mean age of patients was 70 years (60% women, 43 hips, 57 knees) with a mean follow-up of 3 years. 45 cases were early acute or related to wound healing problems, 55 were hematogenous PJI. 25 patients received preoperative antibiotics. 6 of these were culture negative. The mean symptom duration was 7 days. Mean age of the prosthesis was 30 days for early, and 1064 days for the hematogenous group. Conclusions. In our cohort the success rate of DAIR is 94% which indicates that the protocol is highly successful in PJI with short-lasting symptoms and “debridable” joints. Antibiotic protocol violation and duration of symptoms may have a role in failures

Aim. Pelvic osteomyelitis following pressure ulceration results in substantial patient morbidity. Previous studies have reported a heterogenous approach to diagnosis and medical management by physicians, suggesting equipoise on key clinical questions. This study hypothesised that the same equipoise exists amongst Orthopaedic surgeons. Method. An 18-question multiple-choice questionnaire was designed through an iterative feedback process until the final version was agreed by all authors. Likert-type scale responses were used with graded responses (e.g., never/fewer than half of patients/around half of patients/more than half of patients/every patient). The online survey was sent to members of the Musculoskeletal Infection Society (MSIS), the European Bone and Joint Infection Society (EBJIS), and the ESCMID Study Group for Implant-Associated Infections (ESGIAI). No incentive for participation was provided. Results. Amongst respondents, 22/41 were based in Europe and 10/41 from the USA. The majority (29/41) had been in clinical practice between 5—24 years. There was a high priority placed on bone biopsy histology, culture-positive bone sampling, and palpable bone without periosteal covering for diagnosis. Multidisciplinary team approach with plastic surgery involvement at the index procedure was advocated. The strongest indications for surgical intervention were source control for sepsis, presence of an abscess/collection, and prevention of local osteomyelitis progression. Physiological/psychological optimisation and control of acute infection were the primary determinants of surgical timing. There was low utilisation of adjunctive surgical therapies. Local/regional primary tissue transfer or secondary healing with/without VAC were the preferred techniques for wound closure. Recurrent osteomyelitis was the most common reason for prolonged antimicrobial therapy. The majority received bedside advice from an infectious disease-specialist but a quarter of respondents preferred telephone advice. Conclusions. Amongst an international cohort of Orthopaedic Surgeons there was a heterogenous diagnostic and therapeutic approach to pressure-related pelvic osteomyelitis

Abstract Background. The treatment of bone and joint infections (BJI) involving multi-drug resistant bacteria remains a challenge. MDR Staphylococcus epidermidis (MDRSE) clones, resistant to methicillin, clindamycin, levofloxacin, rifampicin and even linezolid, have been reported worldwide. The interest of delafloxacin (DFX), theoretically active on MRSA, remains to be evaluated with respect to MDRSE. Purpose. Our objective was to evaluate during a retrospective multicenter study the DFX minimal inhibitory concentrations (MICs) and compare its efficacy between ofloxacin-susceptible and ofloxacin-resistant S. epidermidis clinical strains involved in BJI. Methods. In this multicenter retrospective study (Reference centers from the West part of France, CRIOGO), 529 strains were collected mostly from BJI. DFX MICs were determined by using a 0.5 Mc Farland bacterial inoculum on Mueller-Hinton agar plates with gradient strips incubated for 24h at 35°C. For S. aureus, breakpoints differentiate skin and soft tissue infections from other infections. Breakpoints followed 2022 EUCAST criteria, with S. aureus values adopted for S. epidermidis. Results. Of the 529 strains collected, 355 were from prosthetic infections, 159 from synthetic infections and 15 from non-device infections. 152 strains were susceptible to ofloxacin (110 males vs 42 females) and 377 resistant (210 vs 167). As presented in Figure 1, all the ofloxacin-susceptible strains presented a DFX MIC ≤0.006mg/L. Resistant strains presented a double population distribution, with 3.7% categorized susceptible according to skin and soft tissues infections breakpoint, against 88.9% according to other breakpoint infections (0.016 or 0.25mg/L respectively). Conclusion. DFX shows excellent activity against ofloxacine-susceptible strains. Concerning the ofloxacin-resistant strains, more than 80% strains or less than 10% can be considered as DFX-susceptible depending on the breakpoints used. Further clinical studies are needed to validate the real breakpoints that must be used in MDRSE BJI, allowing a microbiological cure and a favourable clinical outcome. For any tables or figures, please contact the authors directly

Aim. While 16S rRNA PCR - Sanger sequencing has paved the way for the diagnosis of culture-negative bacterial infections, it does not provide the composition of polymicrobial infections. We aimed to evaluate the performance of the Nanopore-based 16S rRNA metagenomic approach using partial-length amplification of the gene, and to explore its feasibility and suitability as a routine diagnostic tool for bone and joint infections (BJI) in a clinical laboratory. Method. Sixty-two clinical samples from patients with BJI were sequenced on MinION* using the in-house partial amplification of the 16S rRNA gene. BJI were defined based on the ICM Philly 2018 and EBJIS 2021 criteria. Among the 62 samples, 16 (26%) were culture-positive, including 6 polymicrobial infections, and 46 (74%) were culture-negative from mono- and polymicrobial infections based on Sanger-sequencing. Contamination, background noise definition, bacterial identification, and time-effectiveness issues were addressed. Results. Results were obtained within one day. Setting a threshold at 1% of total reads overcame the background noise issue and eased interpretation of clinical samples. The partial 16S rRNA metagenomics approach had a greater sensitivity compared both to the culture method and the Sanger sequencing. All the 16 culture-positive samples were confirmed with the metagenomic sequencing. Bacterial DNA was detected in 32 culture-negative samples (70%), with pathogens consistent with BJI. The 14 Nanopore negative samples included 7 negative results confirmed after implementation of other molecular techniques and 7 false-negative MinION results: 3 Kingella kingae infections detected after targeted-PCR only, 2 Staphylococcus aureus infections and 2 Pseudomonas aeruginosa infections sterile on agar plate media and detected only after implementation of blood culture media, advocating for the very low inoculum. Conclusions. The results discriminated polymicrobial samples, and gave accurate bacterial identifications compared to Sanger-based results. They confirmed that Nanopore technology is user-friendly as well as cost- and time-effective. They also indicated that 16S rRNA targeted metagenomics is a suitable approach to be implemented for routine diagnosis of culture-negative samples in clinical laboratories. * Oxford Nanopore Technologies

Aim. Bone and joint infection requires antimicrobial treatment for 6 to 12 weeks. When patients are well prepared and instructed regarding their therapy, they are more likely to have less side effects and improved compliance. Although side effects are common, this coaching is often not routinely performed when oral treatment is given. We developed a monitoring and guidance program for our outpatients who are on long term antimicrobial therapy, in which we can early signal side effects and treatment failure and coach the patients in their journey of infection treatment. Method. In our tertiary referral centre for orthopaedic infections, we started the outpatient monitoring of antimicrobial treatment (OMAT)- team for patients who will receive antimicrobial therapy for >2 weeks. Before discharge, our trained nurse gives instruction to the patient. Within 3 days after hospital discharge the patient is contacted by phone to, if necessary, clarify ambiguities in monitoring set up. During this contact, the nurse checks for side effects, addresses logistic problems regarding laboratory monitoring or future appointments and coaches patients for other questions. The patient is instructed how to recognize and who to contact in case of red flags and problems possibly related to the treatment. This is repeated after every laboratory check-up. Supervision is performed by an infectious disease specialist in close collaboration with the patient's surgeon. Results. The OMAT-team started in October 2020 and consists of 3 trained nurses and 3 ID specialist. In one year, 453 patients were proactively monitored for a mean of 11 weeks. Routinely, laboratory measurements were performed 1 week after the start of therapy and every 3–4 weeks thereafter, which resulted in 2711 contacts per year. In total, 64% of the patients reported side effects and 13% needed one or more extra laboratory measurement. This led to 40 additional outpatient consultations by the ID specialist because of complications of treatment and a switch of the antimicrobial agent in 31% of the patients. Conclusions. OMAT seems to improve the early signalling of complications regarding treatment, which is likely to improve compliance. The OMAT-team serves as a easy to access team to discuss any problem regarding antimicrobial therapy. Being proactive, the OMAT-team intervenes in an early stage of problems regarding side effects, logistics of the treatment and possible treatment failure. Future analysis of our data will show to what extend this will lead to prevention of re-hospitalization and improvement of success rate

Aim. Diagnosing periprosthetic joint infections (PJI) can be very challenging, especially infections caused by low virulence microorganisms. No single test with a 100% accuracy is available yet. Hence, different infection definitions were introduced to improve the diagnostic confidence and quality of research articles. Due to constant developments in this field, infection definitions are adopted continuously. The aim of our study was to find the most sensitive currently available infection definition among three currently used criteria (International Consensus Meeting – criteria 2018 (ICM), Infectious Diseases Society of America - criteria 2013 (IDSA), and European Bone and Joint Infection Society – criteria 2021 (EBJIS)) for the diagnosis of PJI. Method. Between 2015 and 2020, patients with an indicated revision surgery due to septic or aseptic failure after a total hip or knee replacement were included in this retrospective analysis of prospectively collected data. A standardized diagnostic workup was done in all patients. The components of the IDSA-, ICM-, and EBJIS- criteria for the diagnosis of PJI were identified in each patient. Results. Overall, 206 patients (hip: n=104 (50%); knee: n=102 (50%)) with a median age of 74 years (IQR 65 – 80y) were included. 101 patients (49%) were diagnosed with PJI when using the EBJIS- criteria. Based on the IDSA- and ICM- criteria, 99 patients (48%, IDSA) and 86 patients (42%, ICM) were classified as septic. Based on all three criteria, 84 cases (41%) had an infection. 15 septic cases (n=15/206; 7%) were only identified by the IDSA- and EBJIS- criteria. In 2 patients (n=2/206, 1%), an infection was present based on only the ICM and EBJIS criteria. No case was classified as infected by one infection definition alone. A statistically significant higher number of inconclusive cases was observed when the ICM criteria (n=30/206; 15%) were used in comparison to the EBJIS criteria (likely infections: n=16/206; 8%) (Fisher's exact test, p=0.041). The EBJIS definition showed a better preoperative performance in comparison to the other two definitions (p<0.0001). Conclusions. The most sensitive infection definition seems to be the novel EBJIS– criteria covering all infections diagnosed by the IDSA- and ICM-criteria without detecting any further infection. In addition, less inconclusive (infection likely) cases were detected by the EBJIS-criteria in comparison with the ICM-criteria reducing the so called ‘grey zone’ significantly which is of utmost importance in clinical routine

Aim. At our tertiary orthopaedic centre, mycobacterial cultures are routinely performed on bone and joint samples sent for bacterial culture. We have previously described the prevalence Mycobacterium tuberculosis Complex (MTBC) in these samples. Here, we describe the prevalence of non-tuberculous mycobacteria (NTM). We calculate the number needed to test to identify one previously undiagnosed mycobacterial bone or joint infection. Methods. Samples taken during a single procedure were pooled in one BACTEC MGIT culture. From laboratory records, we ascertained the number of mycobacterial cultures performed, the number positive for MTBC or NTM, and characteristics of individuals from whom mycobacteria were isolated. We collected the same data from 100 individuals with negative mycobacterial cultures. Results presented here are from interim analysis. Results. Excluding sample types that were clearly not bone or joint samples, 6162 mycobacterial cultures were performed between 4 July 2017 and 30 September 2022. Twenty-two patients had MTBC and 6 patients had NTM newly isolated from bone or joint samples placed in mycobacterial culture, with a further patient having both M. tuberculosis and M. avium isolated. In both patients with M. abscessus, the organism also grew in routine bacterial cultures. In one further patient, M. fortuitum was isolated from a sample not put into mycobacterial culture. To identify one new mycobacterial infection of bone or joint (MTBC or NTM) that would not be detected with routine bacterial cultures, 228 (95% CI 157 – 346) mycobacterial cultures were needed. The laboratory cost per additional patient identified using MGIT cultures was €12,540 (95% CI €8,635 - €19,030). Mycobacterial cultures were much less likely to be positive in samples taken from prosthetic joints. They were more likely to be positive in spinal samples and in samples taken from patients with suspected sarcoma. In patients for whom we had contemporaneous histological specimens, these demonstrated granulomatous inflammation in 86% (18/21) of patients from whom MTBC had been isolated but in neither of the two patients from whom only NTM was isolated. Ascertaining the clinical significance of NTM isolates is challenging, although in 2/8 cases the same organism was isolated following repeat sampling. Conclusions. Targeted rather than routine mycobacterial culture of bone and joint specimens should be considered in settings with a low burden of tuberculosis. NTM are rarely isolated from bone and joint specimens at our centre and fast growers may be isolated using routine bacterial culture

Aim. There are no studies in literature that analyze the effectiveness of closed-incisional negative pressure wound therapy (ciNPWT) in the treatment of bone and joint infections (BJI). The aim of the study was to evaluate the efficacy and the safety of the application of ciNPWT in the postsurgical wound management of patients with osteoarticular infections. Method. We conducted a perspective single-center study on patients with BJI treated between 01/2022 and 10/2022 with ciNPWT dressing application at the end of the surgical procedure. All patients were treated by a multidisciplinary team (MDT) approach and operated by the same surgical equipe. Inclusion criteria were: presence of periprosthetic joint infection (PJI), fracture-related infection (FRI), osteomyelitis (OM), septic arthritis (SA) surgically treated, after which ciNPTW was applied over the closed surgical wound. 30 patients (19M, 11F) have been analyzed with mean age of 56,10±17,11 years old; BJIs were all localized in the lower limb (16 PJI, 12 FRI, 1 SA, 1 OM). Results. We considered the following clinical local pre-operative parameters: presence of fistula (10 patients, 33,33%), presence of erythema (18 patients, 60%), presence of previous flap in the incisional site (7 patients, 23,33%). In 11 cases (36,67%) more than 3 previous surgical procedures were performed in the surgical site. The following surgical procedures were performed: 8 debridement and implants removal, 7 DAIR, 3 one-stage exchange, 6 two-stage exchange, 3 spacer exchange, 3 resection arthroplasty. Nineteen patients (63,34%) showed no occurrence of any local post-operative complication (erythema, hematoma, wound breakdown, wound blister, necrosis). Seven (23,33%) patients showed the presence of one or more postoperative complications that didn't require additional surgery. We observed four (13,33%) failures, defined as the need for further surgical procedures following the onset of a local complication: two patients had a wound breakdown before wound closure and two had a recurrence of infection after an uneventfully wound closure. All failures were within the group of joint infection (PJI+SA) and were affected by a multi drug resistant pathogen. Conclusions. In our series four patients required further surgery, but only two cases were related to incisional wound problems, that is consistent with aseptic joint revision surgeries data that are available in literature (3.4%-6.9%)[1-2]. Patients affected by BJI are a group with significant high risk of failure and therefore the use of ciNPWT should be considered. However, randomized clinical trials are needed to establish the superiority of the ciNPWT dressing over the standard one