The increasing number of joint replacement surgeries has led to an increase in periprosthetic joint infections (PJI). Chronic PJI caused by Staphylococcus epidermidis is very common and challenging to treat, prompting interest in bacteriophage therapy. Preclinical studies are essential for optimizing phage administration routes and dosages. Here, phage replication and bacterial growth inhibition using phage and vancomycin were first assessed in vitro. Then, chronic PJI was induced in mice using biofilm-coated titanium implants inoculated with S. epidermidis COB-SE3 to evaluate the efficacy of phage COP-80B and vancomycin therapy. Mice received one intra-articular and two intraperitoneal phage doses over three days, along with vancomycin administered twice daily for five days. Four weeks after implantation, we quantified and compared bacterial loads in periarticular tissues and implants across four groups: untreated controls, phage monotherapy, vancomycin monotherapy, and phage-vancomycin combination. Infection persistence was lower than expected, limiting the ability to detect treatment effects and assess therapeutic efficacy in this low-virulence model. Intra-articular administration of 1010 PFU of COP-80B did not alter plasma alanine aminotransferase levels, indicating no hepatotoxicity. Bacterial isolates remained susceptible to both phage and vancomycin, while phage-neutralizing antibodies developed during treatment. Overall, this study evaluates phage-vancomycin therapy while also contributing a murine model that advances methodological development for chronic S. epidermidis PJI research, with additional refinement of infection kinetics needed to reliably assess therapeutic efficacy.

Background:Corynebacterium spp. is a rare culprit in periprosthetic joint infections (PJIs), with limited data available on outcomes and appropriate treatment course. The aim of this study was to evaluate the success rate of a clinical cohort of patients with PJI, where Corynebacterium spp. was the causative organism (CPJI), treated according to an institutional algorithm based upon European Bone and Joint Infection Society guidelines. Methods:From the institutional bone infection registry, 44 patients treated for CPJI between 2007 and 2023 were identified. CPJIs were divided into 2 groups according to the isolated microbes: monomicrobial (14 [32%]) and polymicrobial (30 [68%]). Patients were treated with debridement, antibiotics, and implant retention (DAIR; 14 [32%]) or with 1- or 2-stage implant exchange (reimplantation group; 30 [68%]). In 13 (30%) cases, antibiotic combination with rifampicin was used. Results:Out of 44 patients, 4 required further treatment. In monomicrobial CPJI, the treatment course was successful in all patients, whereas in polymicrobial CPJI it was successful in 87%. Antibiotic combination including rifampicin was used in 4 monomicrobial cases (29%) and 9 polymicrobial (30%) cases. In the polymicrobial group, DAIR was successful in 90% (9/10), while the reimplantation group had an 85% (17/20) success rate. Conclusions:In contrast with the previously published papers on CPJI, the results in our cohort were good, with the total cure rate being 91%. The cure rate was slightly lower in the polymicrobial group compared with the monomicrobial: 87% and 100%, respectively. Surgical therapy according to the established institutional algorithm resulted in a high success rate.

Aims Periprosthetic joint infections (PJIs) pose significant challenges to patients and healthcare systems worldwide. The aim of this study was to estimate the health-economic burden of reimbursement payment in Europe for PJIs following primary hip and knee arthroplasty. Methods The calculation was based on health-economic modelling using data on primary hip and knee arthroplasties for the year 2019 from the Statistical Office of the European Union (Eurostat) and published infection rates to estimate the total number of hip and knee PJIs in 30 European countries. Revision procedures were stratified into: 1) debridement, antibiotics, and implant retention (DAIR); 2) one-stage exchange; and 3) two-stage revision procedures. The cases were then multiplied by the respective healthcare system reimbursement payments. Payment data were acquired from a survey of 13 countries (Austria, Croatia, France, Germany, Italy, Lithuania, Netherlands, Norway, Portugal, Slovenia, Switzerland, Turkey, and the UK) and extrapolated for the remaining countries. Results In 2019, a total of 2,048,778 primary total joint replacements were performed (total hip arthroplasty (THA) = 1,147,316 and total knee arthroplasty (TKA) = 901,462), with an estimated 20,416 cases of PJIs (11,131 hip and 9,285 knee) in Europe. This results in an estimated total reimbursement burden of 346,262,026 for European healthcare systems. The breakdown for hip PJI reimbursement was 197,230,953 (9,751,962 for DAIR procedures, 45,135,894 for one-stage revisions, and 142,343,097 for two-stage revisions). For knee PJIs, the analysis yielded a total reimbursement of 149,031,073 (9,335,075 for DAIR procedures, 48,058,479 for one-stage revisions, and 91,637,518 for two-stage revisions). Conclusion This is the first study to evaluate the health-economic burden of PJIs in Europe, revealing a substantial impact on healthcare systems with an estimated case load of 20,414 cases and overall reimbursement of 346,262,026 for primary THAs and TKAs performed in 2019.

Genome-wide association studies have identified multiple loci associated with bone mineral density, a major determinant of osteoporotic fracture risk. At one such locus, genetic, bioinformatic, and zebrafish knockout data strongly prioritize membrane palmitoylated protein 7 (MPP7) as a candidate gene, although its precise role in bone biology remains poorly defined. MPP7 encodes a member of the p55 Stardust family of membrane-associated guanylate kinase proteins, which are key regulators of epithelial cell polarity and junctional organization. Here, we investigated the functional role of MPP7 in bone biology. We found that MPP7 expression was significantly reduced—by approximately twofold—in bone tissue from osteoporotic patients compared with osteoarthritic patients and non-osteoporotic controls. Furthermore, we generated a CRISPR/Cas9-mediated MPP7 knockout in the human osteosarcoma HOS cell line and demonstrated that MPP7 deletion impairs osteogenic differentiation and completely abrogates mineralization through downregulation of ALPL expression. Knockout cells also displayed altered morphology, suggesting that MPP7 influences osteoblast function via effects on cell polarity and adhesion. Collectively, our findings, together with zebrafish genetic evidence, indicate that MPP7 plays a critical role in osteoblast differentiation and mineralization and may contribute to osteoporosis susceptibility in humans.

Background and Clinical Significance: Trichoderma is a rare cause of human fungal infections. These infections are often severe and can be life-threatening, involving various organs and tissues. Although Trichoderma is not commonly encountered in clinical practice, its ability to cause infections is particularly significant in immunocompromised patients. As a result, cases in which Trichoderma is identified in human specimens are not only uncommon but also pose complex diagnostic and therapeutic challenges for clinicians. Although it can be associated with various organs, its clinical significance in joints, especially in periprosthetic joint infections, remains unclear. Case Presentation: This case report presents a 63-year-old immunocompromised woman with a suspected periprosthetic joint infection caused by Trichoderma. After total hip arthroplasty and subsequent bacterial periprosthetic joint infection, Trichoderma was revealed from two intraoperative samples. Given the unusual pathogen and the patient’s immunosuppression, antifungal therapy with amphotericin B was initiated. However, due to severe intolerance, the antifungal treatment had to be discontinued shortly after initiation, and the patient continued under close monitoring. We closely monitored the patient’s clinical status and laboratory test results, continuously considering whether the findings represented contamination or true infection. The patient exhibited clinical and radiological stability, reinforcing the hypothesis of contamination rather than active infection. Conclusions: This case explores the rarity of Trichoderma periprosthetic joint infections, the diagnostic and treatment challenges, and the importance of multidisciplinary input in managing such uncommon and complex cases. Further studies are needed to clarify the pathogenic significance, optimal management, and long-term outcomes of Trichoderma in bone and joint infections.

BACKGROUND:The reported success rate of debridement, antibiotics, and implant retention (DAIR) for periprosthetic joint infection varies considerably between studies, despite institutions reporting use of the same procedure. In this narrative review, we aim to delineate the differences between the various DAIR approaches and highlight why they influence the outcome. OBJECTIVES:We performed a PubMed and internet search investigating the different approaches for DAIR and their associated outcomes. SOURCES:Twenty-two studies with defined infection criteria, consisting of 50 or more periprosthetic joint infection cases and a follow-up of 1 year or longer, were included. CONTENT:Most studies did not report whether the presence of a sinus tract was a criterion for not performing DAIR, and the use of biofilm-active agents for curative DAIR was only reported in a few studies. The duration of infection as criterion for early postoperative and acute haematogenous infection varied between studies. The epidemiology of host factors and microorganisms, healthcare systems, patient-doctor interactions, and decision-making processes for surgical interventions vary worldwide, and so do the indications for DAIR. IMPLICATIONS:Studies should precisely declare the indication for DAIR, the variables that influence decision-making for treatment options, the surgical technique applied, and the type and duration of antimicrobial therapy. Such an approach will increase the quality of research data and allow the development of recognized subcategories of DAIR.

In the absence of standard criteria for prosthetic joint infections (PJI), several diagnostic modalities have been proposed mostly concentrating on novel biochemical markers. The physical chemistry markers received scarce attention. Synovial fluid (SF) viscosity could be considered as marker for PJI, however, its diagnostic value of PJI remains unknown. Our study aimed to determine the potential of SF viscosity as a diagnostic marker of PJI and compare it to SF cell count with differential (CCD). We prospectively analysed 123 SF samples (58 septic and 65 aseptic) for viscosity and CCD of SF obtained during hip and knee revision procedures. The diagnosis of PJI based on EBJIS criteria. The viscosity cut-off for PJI was calculated and the diagnostic power was compared to CCD. The mean SF viscosity in the PJI group was 8.5 ± 0.4 mPa s and 103.2 ± 18.8 mPa s in the aseptic group (p < 0.05). SF viscosity achieved 100% sensitivity and 85.3% specificity, with AUC 0.832 (95% CI 0.739, 0.925). Combination of SF viscosity and CCD achieved AUC 0.951 (95% CI 0.919, 0.987). SF viscosity is more sensitive but slightly less specific in diagnosing PJI than SF CCD. Best diagnostic value is achieved combining SF viscosity with CCD in detection of PJI.

Background:Hip abductor mechanism deficiency due to abductor tendon degeneration, tear, or intraoperative damage during total hip arthroplasty (THA) may cause severe walking disability. For severe abductor weakness in native hip joints, Whiteside muscle transfer is a good solution. However, the literature on the results of abductor mechanism reconstruction (AMR) after THA remains limited. Our study aimed to assess the outcome of AMR in patients with THA suffering from Milwaukee III and IV hip abductor deficiency. Methods:We conducted a single-center retrospective cohort study of THA with hip abductor mechanism deficiency treated surgically with AMR. Data were collected between January 2011 and December 2019 and included the following parameters: patient's data, subjective level of pain, Harris Hip Score (HHS), gait pattern, extent of hip abductor tear, and offset measurements. Results:The cohort included 16 THAs with AMR in 16 patients. The whole group median HHS improved from 37.1 interquartile range (IQR) (31.0-38.7) to 73.9 IQR (63.5-83.7) (P < .001). In a subgroup of 9 hips, the global offset was preserved after THA while it was reduced in remaining 7 hips. All patients with preserved global offset had significantly better clinical outcome compared to the group with reduced global offset (median HHS improvement was 48 IQR [46-53] compared to 22 IQR [18-25], P = .001). Conclusions:Our study showed favorable outcome of the AMR for chronic, Milwaukee III and IV hip abductor deficiency after THA. It is the first study to show that restoration of global offset after THA is of utmost importance to avoid chronic abductor mechanism deficiency.

Phage therapy has recently attracted significant attention as a potential treatment for periprosthetic joint infections, yielding promising outcomes in several compassionate use cases. The absence of standardized treatment protocols is partly attributable to insufficient pharmacokinetic data regarding relevant phage administration routes and dosages. Another neglected aspect is the scalable manufacturing of pharmaceutical-grade phage preparations for preclinical testing. In this study, we address both challenges and present a scalable phage production process for the Staphylococcus epidermidis-specific phage COP-80B We prepared a highly purified phage suspension, as verified through qPCR, HPLC, NTA and short-read sequencing, which was used in a preclinical pharmacokinetic study in an uninfected mice model. Using a plaque assay, we determined phage concentrations in mouse organs over time after intraperitoneal and intra-articular application of 109 phages. Intra-articularly administered phages persisted in the periarticular tissue for several days, entered the systemic circulation and were subsequently cleared from the liver and spleen. Conversely, intraperitoneally administered phages did not reach the intra-articular space. No adverse events and no changes in hematological parameters were observed in mice after phage application by either route, confirming the safety of a single-dose application. Our results emphasize the importance of local phage administration for sustained presence in periarticular tissue and provide valuable pharmacokinetic data to support the development of optimized treatment protocols for periprosthetic joint infections.

Background: Patients with rheumatoid arthritis (RA) with late acute periprosthetic joint infections (PJIs) treated with surgical debridement, antibiotics, and implant retention (DAIR) have a high failure rate. We conducted a case-control study to identify risk factors for DAIR failure in this specific patient population. Methods: Data from an international multicenter retrospective observational study were used. Late acute PJI was defined as a sudden and acute onset of PJI symptoms occurring more than 3 months after implantation in a previously asymptomatic joint. Cases with RA were matched with cases without RA based on the affected joint. A multivariate Cox regression, stratified for RA, was used to identify risk factors and calculate hazard ratios (HRs) for failure. Subgroup analysis was done to explore the role of immunosuppressive therapy. Results: A total of 40 patients with RA and 80 control patients without RA were included. The use or continuation of immunosuppressive drugs was not associated with a higher failure rate. No significant association was found between the duration of symptoms, causative microorganisms, and therapy failure. Bacteremia was an independent predictor for treatment failure (HR of 1.972; 95 % confidence interval, CI, of 1.088-3.573; p = 0.025), and the exchange of modular components was associated with a lower risk of treatment failure (HR of 0.491; 95 % CI of 0.259-0.931; p=0.029 ). Conclusion: In patients with RA and a late acute PJI treated with DAIR, bacteremia is an important predictor of treatment failure. Exchanging the modular components seems to be especially important in this patient group and is associated with a lower failure rate.

To evaluate the diagnostic value of next-generation sequencing (NGS) in patients with suspected periprosthetic joint infection (PJI), using European Bone and Joint Infection Society (EBJIS) criteria for case definition. We are prospectively including patients undergoing revision surgery for suspected PJI. Diagnosis was established according to the EBJIS criteria. In addition to routine microbiological diagnostics (synovial fluid, periprosthetic tissue, and sonication fluid cultures), all available samples from each patient will be also processed for NGS. DNA extraction and human DNA depletion were performed using the Molzym Ultra-Deep Microbiome protocol, followed by library preparation, metagenomic sequencing and taxonomic profiling. Clinical, demographic, and microbiological data were collected and analysed, focusing on concordance between NGS findings and culture results and their relevance to the clinical diagnosis. A total of 75 patients are currently included in the cohort. Based on EBJIS criteria, 33 were classified and treated as PJI. NGS was performed on joint and sonication fluid from four random patients. The proportion of human DNA in all analysed samples was acceptably low, indicating effective depletion of host DNA during the extraction process. In two patients with confirmed Staphylococcus epidermidis PJI, both culture and NGS identified the same pathogen. The proportion of bacterial DNA was higher in the sonication fluid compared to joint fluid, and coverage depth for S. epidermidis was also greater in sonication-derived samples. In one patient not treated as infection, NGS detected Cutibacterium acnes DNA in both joint and sonication fluid. However, the patient had no clinical signs of infection and has remained asymptomatic during follow-up, indicating likely contamination. In another patient treated as PJI based on clinical and laboratory criteria, but with negative cultures, NGS revealed only a very low bacterial DNA signal in both sample types, with no identifiable pathogen. NGS shows promise as an adjunct tool in the diagnosis of PJI, particularly in cases with inconclusive culture results. As further samples are processed, we look forward to expanding our dataset and identifying meaningful trends. Defining a diagnostic threshold for bacterial DNA percentage will be essential to improve interpretability. Given the complexity of NGS results, additional analyses such as metagenomic assembly and resistance gene identification are planned to complement taxonomic profiling and enhance pathogen characterization. Close collaboration with microbiologists or sequencing specialists will likely remain crucial for clinical decision-making.

(1) Background: Analyses of retrieved inserts allow for a better understanding of TKA failure mechanisms and the detection of factors that cause increased wear. The purpose of this implant retrieval study was to identify whether insert volumetric wear significantly differs among groups of common causes of total knee arthroplasty failure, whether there is a characteristic wear distribution pattern for a common cause of failure, and whether nominal insert size and component size ratio (femur-to-insert) influence linear and volumetric wear rates. (2) Methods: We digitally reconstructed 59 retrieved single-model cruciate-retaining inserts and computed their articular load-bearing surface wear utilizing an optical scanner and computer-aided design models as references. After comprehensively reviewing all cases, each was categorized into one or more of the following groups: prosthetic joint infection, osteolysis, clinical loosening of the component, joint malalignment or component malposition, instability, and other isolated causes. The associations between volumetric wear and causes of failure were estimated using a multiple linear regression model adjusted for time in situ. Insert linear penetration wear maps from the respective groups of failure were further processed and merged to create a single average binary image, highlighting a potential wear distribution pattern. The differences in wear rates according to nominal insert size (small vs. medium vs. large) and component size ratio (≤1 vs. >1) were tested using the Kruskal–Wallis test and the Mann–Whitney test, respectively. (3) Results: Patients with identified osteolysis alone and those also with clinical loosening of the component had significantly higher volumetric wear when compared to those without both causes (p = 0.016 and p = 0.009, respectively). All other causes were not significantly associated with volumetric wear. The instability group differentiated from the others with a combined peripheral antero-posterior wear distribution. Linear and volumetric wear rates showed no significant differences when compared by nominal insert size (small vs. medium vs. large, p = 0.563 and p = 0.747, respectively) or by component (femoral-to-insert) size ratio (≤1 vs. >1, p = 0.885 and p = 0.055, respectively). (4) Conclusions: The study found increased volumetric wear in cases of osteolysis alone, with greater wear when combined with clinical loosening compared to other groups. The instability group demonstrated a characteristic peripheral anterior and posterior wear pattern. Insert size and component size ratio seem not to influence wear rates.

AimThere is limited data on the frequency and impact of untoward events such as glove perforation, contamination of the surgical field (drape perforation, laceration, detachment), the unsterile object in the surgical field (hair, sweat droplet…), defecation, elevated air temperature…that may happen in the operating theatre. These events should influence the surgical site infection rate but it is not clear to what extent. We wanted to calculate the frequency and measure the impact of these events on the infection and general revision rate.MethodIn our institution, scrub nurses prospectively and diligently record untoward events in the theatres. We have an institutional implant registry with close to 100% data completion since 2001, and surgeons register complications before discharge. We analysed the respective databases and compared the revision and infection rate in the group with untoward events with the outcome of all arthroplasty patients within the same period. Two-tailed Z statistical test was used for analysis.ResultsBetween 1.1.2012 and 31.12.2018 we operated 13574 prosthetic joints: 6232 primary THR (total hip replacement) and 5466 primary KR (total and partial knee replacement) and 1245 and 631 revisions respectively. During this period, we recorded 372 events (2.74%) including 20 (0.15 %) defecations, 40 (0.29 %) unsterile object in the surgical field, 73 (0.54%) field sterility violations, 45 (0.33 %) glove perforations, 45 (0.33 %) occasions with elevated air temperature, 106 (0.78%) with guests in the OR, 11 (0.08%) with wound near the surgical field, and 32 (0.24%) with other events. We followed the patients till 1.1.2022, in this time we recorded 27 (7.26%) reoperations in the cohort with untoward events. There were 9 (2.42%) infections and 18 (4.84%) aseptic revisions in the group with unwanted events.The infection rate for all TJR (total joint replacement) from the period 2012-2018, followed till 1.1.2022 was 2.23%, the revision rate for any reason was 4.37%. For all THR (primary and revision) the infection rate was 0.84%, the overall revision rate was 3.18% and for the KR (primary and revision) 1.71% and 5,82% respectively. The difference is significant at p>0.05 for infection rate.ConclusionsThe potentially serious sterility disruptive events in the operative rooms did result in an increased infection rate but not an increase in revision rate. There is no data about the rate and the impact of these events besides for perforated surgical gloves with higher reported incidences than in our study influencing infection rate if perioperative antibiotic prophylaxis was not used. Ours is the first study reporting the impact of these unwanted events in the operating theatre.Key wordsorthopaedic surgery, unwanted events, revision rate

AimPeriprosthetic joint infection (PJI) is one of the most devastating complications after joint replacement. It is associated with high morbidity and economic burden when misdiagnosed as an aseptic failure. Among all cases of PJI, up to 25% could yield negative cultures. Conversely, among cases of aseptic failures, up to 30% may actually be undiagnosed PJIs. In PJIs microbiological diagnosis is a key step for successful treatment. Sonication of the removed prosthesis is more sensitive than conventional periprosthetic-tissue culture, especially in patients who received antimicrobial therapy before surgery. This study aimed to compare the diagnostic value of classic sonication fluid cultures (SF-C) and sonication fluid incubation in blood culture bottle (SF-BCB).MethodBetween 2016 and 2018 we analysed 160 revision procedures of joint arthroplasties. For each procedure, at least 5 microbiological and multiple histopathological samples were harvested, and explant sonication was performed which was further analysed by SF-C and SF-BCB. For SF-C classical cultivation of sonication fluid was performed. While for SF-BCB, 10 mL of sonication fluid was inoculated into aerobic and anaerobic lytic blood culture bottles. The definite diagnosis of PJI was based on the EBJIS definition.ResultsAmong 160 revisions, 59 PJIs were identified, 15 patients were treated with the debridement and implant retention, 7 patients with the one-stage and 35 with the two-stage exchange, remaining 2 were partial revisions. The sensitivity of SF-C and SF-BCB were 81.5% and 94.9%, respectively. The mismatch of microbe identification was observed in 5 cases. We observed positive SF-C while negative SF-BCB in 4 cases, among them having 2 positive histology. While 12 patients have negative SF-C and positive SF-BCB, among them 3 have positive and 6 negative histology. Among these 12 patients, typical low-grade microbes were identified in 9 cases (5 cases of C. acnes, 3 cases of S. epidermidis, and 1 case of S. capitis).ConclusionsThe weakest point in all PJI diagnostic criteria is their sensitivity. SF-BCB demonstrates higher sensitivity in diagnosing PJI compared to SF-C. Therefore, it appears prudent to incorporate SF-BCB into the diagnostic protocol for all patients exhibiting either low-grade PJI symptoms or experiencing undiagnosed, presumably aseptic failures, where the likelihood of misdiagnosing infection is greatest.

Case: A 64-year-old male patient sustained a fracture of the humeral diaphysis on falling from a bicycle. During surgery, pus drainage from the intramedullary canal indicated infection, and cultures were positive for pansensitive Clostridium perfringens . After initial stabilization, imaging showed inadequate fragment contact, leading to referral to our bone infection unit. A revision surgery with plate osteosynthesis was performed. Intravenous and oral antibiotic therapy was administered. Oral antibiotics were continued until 12 weeks postoperatively. At the 26-month follow-up, the patient presented with a good functional outcome. Conclusion: Fracture-related infections (FRI) pose serious complications, requiring swift surgical intervention. Although C. perfringens infections in FRIs are rare and literature is scarce, this case highlights the successful management and good functional outcome, offering valuable insights for clinicians dealing with such infections.

Introduction: The BIOFIRE Joint Infection (JI) Panel is a diagnostic tool that uses multiplex-PCR testing to detect microorganisms in synovial fluid specimens from patients suspected of having septic arthritis (SA) on native joints or prosthetic joint infections (PJIs). Methods: A study was conducted across 34 clinical sites in 19 European and Middle Eastern countries from March 2021 to June 2022 to assess the effectiveness of the BIOFIRE JI Panel. Results: A total of 1527 samples were collected from patients suspected of SA or PJI, with an overall agreement of 88.4 % and 85 % respectively between the JI Panel and synovial fluid cultures (SFCs). The JI Panel detected more positive samples and microorganisms than SFC, with a notable difference on Staphylococcus aureus, Streptococcus species, Enterococcus faecalis, Kingella kingae, Neisseria gonorrhoeae, and anaerobic bacteria. The study found that the BIOFIRE JI Panel has a high utility in the real-world clinical setting for suspected SA and PJI, providing diagnostic results in approximately 1 h. The user experience was positive, implying a potential benefit of rapidity of results' turnover in optimising patient management strategies. Conclusion: The study suggests that the BIOFIRE JI Panel could potentially optimise patient management and antimicrobial therapy, thus highlighting its importance in the clinical setting.

A 68-year-old man was referred due to bilateral hip pain and gradual deterioration of walking. He had mold arthroplasties on both hips at the age of 7 years and has been functioning well for more than 5 decades. However, the original data on operative report and the prostheses were missing. The radiological examination revealed bilateral broken prosthetic material. Thus, stage bilateral revision total hip arthroplasty was performed. A detailed chemical analysis of retrieved mold arthroplasty implants proved that the acrylic material was noted to be the same composition with the difference in appearance likely being related to different thermal treatments originally applied to the implants. As presented in our clinical case, even obsolete implants may have good survivorship. According to the case presented, total hip arthroplasty could be considered an effective option with the desired functional outcome when conservative and joint-preserving measures are exhausted.

Prosthetic joint infections (PJIs) are commonly diagnosed via culture-based methods, which may miss hard-togrow pathogens. This study contrasts amplicon metagenomic sequencing (16S AS) with traditional culture techniques for enhanced clinical decision-making. We analyzed sonicate fluid from 27 patients undergoing revision arthroplasty using both methods, emphasizing the distinction between contaminants and true positives. Our findings show moderate agreement between the two methods, with a Cohen's kappa of 0.490, varying across bacterial genera (Cohen's kappa -0.059 to 1). The sensitivity of 16S AS compared to culture was 81% (95% CI, 68% to 94%). Sequencing revealed greater microbial diversity, including anaerobic genera like Anaerococcus and Citrobacter. Interestingly, several culture-negative PJI samples showed diverse bacteria via 16S AS. Despite rigorous controls and algorithms to eliminate contaminants, confirming bacteria presence with 16S AS remains a challenge. This highlights the need for improved PJI diagnostic methods, while also pointing out the limitations of next-generation sequencing (NGS) as a clinical diagnostic tool.

To identify clinical and laboratory predictors for low- and high-grade prosthetic joint infection (PJI) within the first postoperative days following primary total hip/knee arthroplasty (THA/TKA). Institutional bone and joint infection registry of a single osteoarticular infection referral centre was reviewed to identify all osteoarticular infections treated between 2011 and 2021. Among them were 152 consecutive PJI (63 acute high-grade PJI, 57 chronic high-grade PJI, and 32 low-grade PJI) who also had primary THA/TKA performed at the same institution, which were retrospectively analyzed with multivariate logistic regression and covariables. For each additional day of wound discharge, persistent wound drainage (PWD) predicted PJI in the acute high-grade PJI group with odds ratio (OR) 39.4 (p = 0.000, 95