Aim. Two types of national registers surveil infections after primary total hip arthroplasty (THA) in Norway: The National surveillance system for surgical site infections (NOIS) that surveil all primary THAs 30 days postoperatively for surgical site infections (SSI), and the Norwegian Arthroplasty Register (NAR) that follow all THAs until any surgical reoperation/revision or the death of the patient. Since these registers report on the same THAs we assessed correspondence between and time trends for the two registers in period 2013 to 2022. All reported THAs were included. Method. The THAs were matched on a group level according to sex, age and ASA-class. In addition to descriptive statistics, adjusted Cox regression analyses were performed with adjustment for sex, age group (<45, 45-54, 55-64, 65-74, 75-84, >85 years) and ASA-class (1, 2, 3, 4 and missing). Changes in annual incidence and adjusted hazard rate (aHR) was calculated. Endpoints in the NOIS were 30-Days SSI and 30-Days reoperation for SSI. Endpoints in the NAR were 30-Days and 1-Year reoperation for periprosthetic joint infection (PJI). Results. The NOIS had registered 87,923 THAs with 1,393 (1.58%) SSIs and 765 (0.87%) reoperations for SSI within 30 postoperatively. The NAR had registered 91,194 THAs with 725 (0.80%) reoperations for infection after 30 days, and 1,019 (1.21%) reoperations for infections after one year. The distribution of sex, age and ASA-class was near identical in the two registers. There was a mean annual reduction in risk of both SSI (aHR 0.92 (95% CI 0.90-0.93)) and reoperation for SSI (0.95(0.92-0.97)) and PJI (30-Days: 0.96 (0.94-0.99), 1-Year: 0.95-0.99)) over the period 2013-2022. Conclusions. The NOIS and the NAR have excellent completeness and the registrations in both registers may be considered representative for the Norwegian population. Not all SSI are reoperated. The incidence and risk of SSI (NOIS) and reoperation for PJI (NAR) is declining and may reflect a true reduction in incidence of PJI after primary THA

Aim. This study aims to evaluate the effectiveness of a pre-formulated irrigation solution. 1. (containing ethanol, acetic acid, sodium acetate, benzalkonium chloride, and sterile water) compared to saline solution in managing acute periprosthetic joint infections (A-PJI) during Debridement, Antibiotic, and Implant Retention (DAIR) surgeries. The primary objective is to assess the healing rate using this solution. 1. versus saline in A-PJI patients, with “cure” defined by a set of criteria including no recurrence, wound issues, or need for ongoing suppressive antibiotics after 1 year. Principio del formularioFinal del formulario. Method. This single-center, randomized controlled trial will involve patients with acute periprosthetic infections undergoing standard DAIR surgery, divided into two groups: one receiving saline solution and the other receiving pre-formulated solution. 1. The study is single-blinded, with patients unaware of their group assignment. The study is registered at ISRCTN: https://doi.org/10.1186/ISRCTN10873696. Inclusion criteria include patients over 18 with hip or knee prostheses suffering from acute or hematogenous periprosthetic infections, while exclusion criteria include a history of prior debridement or multiple infected implants, among others. Principio del formularioFinal del formulario A total of 50 subjects are needed for statistical significance, with a 5% dropout rate anticipated. An interim safety analysis will assess early effectiveness and adverse effects, and the results are presented in this study. Data will be managed in online databases and analyzed using SPSS software, with a significance level of p<0.05. Results. Twenty-four patients were eligible for analysis, twelve in each group. The overall average age was 75 years, and the gender distribution was predominantly female (9 F and 3 M in each group). No significant differences were found at the baseline characteristics level between the two groups (p>0.05). The minimum follow-up of 1 year was achieved in all cases except three due to deaths not related to periprosthetic infection. Regarding efficacy, a non-statistically significant difference was observed (p>0.05), with 58% in the serum group and 42% in the pre-formulated irrigation solution. 1. group (X. 2. = 0.17, p=0.683). The average hospital stay was 38.42 days (SD 26.32) in the pre-formulated irrigation solution group. 1. and 24.42 days (SD 18.72) in the serum group, with this difference being not significant (t=1.5, p=0.148). Conclusions. While the current analysis indicates no significant differences between both groups in terms of efficacy, the study's ongoing progress and the inclusion of a larger sample size could potentially yield more definitive results

Aim. This retrospective study evaluated the outcome of treatment for unhealed fracture-related infections (FRI). Methods. We identified a consecutive, single-centre cohort of patients having treatment for an FRI Consensus confirmed FRI. All fractures were unhealed at the time of treatment. Patients were followed up for at least one year. Successful outcome was a healed fracture without recurrent infection. Lack of union, persistent infection and/or unplanned reoperation defined failure. Results. Demographics: 183 patients (184 FRIs) with mean age 52.1 years (range 17-96) were treated and followed up for a mean of 2.8 years (range 1-9.4). Mean duration of FRI was 1.1 years with 65 (35.5 %) presenting within 6 months of injury. 118 patients had established infected non-union. FRI was most frequent in the tibia (74), femur (48) and humerus (24). 171 patients were BACH Complex. 75.5% of FRIs were culture positive, with Staph. aureus being the most frequent organism. Polymicrobial infection and Gram negative cultures were common (25.5% and 33.6%). Treatment: 98.3% of surgeries were performed in one stage with just 3 planned 2-stage procedures (2 endoprosthetic replacements and 1 free fibular flap). No bone graft was used in any surgery and all wounds were closed at first operation. 48 cases (26%) required flap coverage (29 free flaps and 19 local flaps). Local antibiotics were used in 124 cases (67.4%) of primary surgeries. All patients had sampling, debridement, systemic antibiotics and wound closure. 40 (21.7%) had DAIR, 31 (16.8%) had new internal fixation and 105 (57.1%) had external fixation (including 79 Ilizarov fixators). Outcomes: After primary surgery, 84.6% of all patients were infection-free and 77.2% had united. After further surgery, 98.8% were infection-free and 98.1% had united. External fixation techniques achieved infection eradication in 89.1% compared to 71.7% with any internal fixation (p=0.005). Primary internal fixation achieved union in 81.7% compared to 74.3% with external fixation (p=0.27). Secondary surgery after external fixation was mainly docking site fixation. Conclusion. Unhealed FRIs present a difficult challenge for treatment. This large series demonstrated that single-stage treatment, without bone grafting, gave acceptable results with few reoperations. Primary external fixation gave more certainty of infection eradication but required more reoperations to secure union. However, this difference in reoperation was not statistically significant. We strongly advocate managing these patients with a multidisciplinary team which can treat all aspects of the condition

Aims

Pain is the most frequent complaint associated with osteonecrosis of the femoral head (ONFH), but the factors contributing to such pain are poorly understood. This study explored diverse demographic, clinical, radiological, psychological, and neurophysiological factors for their potential contribution to pain in patients with ONFH.

Aim. The current recommendation in Norway is to use four doses of a first-generation cephalosporin (cefazolin or cephalotin) as systemic antibiotic prophylaxis (SAP) the day of surgery in primary joint arthroplasty. Due to shortage of supply, scientific development, changed courses of treatment and improved antibiotic stewardship, this recommendation has been disputed. We therefore wanted to assess if one dose of SAP was non-inferior to four doses in preventing periprosthetic joint infection (PJI) in primary joint arthroplasty. Method. We included patients with primary hip- and knee arthroplasties from the Norwegian Arthroplasty Register and the Norwegian Hip Fracture Register for the period 2005-2023. We included the most used SAPs (cephalotin, cefazolin, cefuroxime, cloxacillin and clindamycin), administered as the only SAP in 1-4 doses, starting preoperatively. Risk of revision (Hazard rate ratio; HRR) for PJI was estimated by Cox regression analyses with adjustment for sex, age, ASA class, duration of surgery, reason for- and type of arthroplasty, and year of primary arthroplasty. The outcome was 1-year reoperation or revision for PJI. Non-inferiority margins were calculated for 1, 2 and 3 doses versus reference of 4 doses of SAP at the day of surgery, against a predetermined limit of 15% increased risk of PJI. Results. In total 274,188 primary arthroplasties (total hip 133,985, hemi hip 51,442, and total knee 88,761) were included. Of these primary arthroplasties, 2,996 (1.1%) had subsequent revisions for PJI during the first postoperative year. One dose of SAP was given in 9,603 arthroplasties, two doses in 10,068, three doses in 18,351, and four doses in 236,166 arthroplasties. With the recommended four doses as reference, the HRR (95% CI) for 1-year revision for infection was 0.9 (0.7-1.1) for one dose, 1.0 (0.8-1.2) for two doses, and 0.9 (0.8-1.1) for three doses. The corresponding adjusted 1-year revision incidences for PJI was 0.9 (0.7-1.1), 1.0 (0.8-1.2), 0.9 (0. 8-1.1) and 1.0 (1.0-1.1) for one, two, three and four doses respectively, and less than four doses was found to be non-inferior. Conclusions. One preoperative dose of SAP in primary joint arthroplasty surgery seems to be non-inferior to the current recommendation of four doses of a first-generation cephalosporin as PJI-prophylaxis. This finding may simplify the course of treatment for arthroplasty patients, save costs, and improve antibiotic stewardship

Aim. The primary objective is to evaluate the diagnostic performance of inoculating homogenized tissue and bone biopsies in blood culture bottles (BCB) for patients with (suspected) orthopaedic device-related infections. As secondary objective the time to positivity (TTP) of BCB and Wilkins-Chalgren broth (conventional method) will be evaluated. Method. Patients undergoing revision surgery due to suspected or proven fracture-related infection (FRI) or periprosthetic joint infection (PJI) according to respectively Consensus definition and EBJIS definition are included. 1,2. A minimal of three macroscopic infected/inflamed tissue/bone samples are collected in a container with saline and glass beads. 1.5 mL of the homogenized suspension is inoculated in BacT/ALERT FA and FN Plus bottles for 14 days. The remaining suspension is inoculated in Wilkins-Chalgren broth for 10 days and subcultured when cloudy or after 10 days. TTP is defined as the time until definite identification of the pathogen in the Laboratory Information System. Results. Up to now, 25 patients have been included, 11 (44%) had concordant results in BCB and the CM. In 11 patients cultures showed negative results for both methods. Three patients tested positive with BCB but remained negative with the same pathogen in CM. In the first patient, the CM failed to identify anaerobic bacteria (i.e. Fusobacterium nucleatum). In the second patient, three BCB were positive with Staphylococcus capitis. The third patient showed an infection with Escherichia coli, which was detected in all samples from the BCB, while all cultures obtained with the CM remained negative. A possible explanation for this discrepancy could be that this patient already received antibiotic therapy. BCB contain resins, which are capable of neutralizing antibiotic activity. Another case illustrating superiority of BCB involved an infection with Cutibacterium acnes, which showed positivity in six BCB, while only three were positive using the CM. We observed the shortest TTP with BCB. The median TTP of BCB was 32.0 hours (IQR 29.8) compared to a median TTP of 77.5 hours (IQR 107.6) when culturing with the CM. Contamination was seen in three patients with both methods, in eight patients contamination was only seen with the CM. For the remaining 14 patients no contamination was found. Conclusions. The results in this ongoing study indicate that the recovery of pathogens and TTP is better using BCB compared to CM. In addition, contamination occurs less frequently with the BCB method. Culturing tissue or bone biopsies in BCB seems a promising and faster detection method

Aim. Periprosthetic joint infections follow 1-3% of arthroplasty surgeries, with the biofilm nature of these infections presenting a significant treatment challenge. 1. Prevention strategies include antibiotic-loaded bone cement; however, increases in cementless procedures means there is an urgent need for alternative local antimicrobial delivery methods. 2. A novel, ultrathin, silica-based sol-gel technology is evaluated in this research as an anti-infective coating for orthopaedic prosthetic devices, providing local antibiotic release following surgery. Method. Reduction in clinically relevant microbial activity and biofilm reduction by antimicrobial sol-gel coatings, containing a selection of antibiotics, were assessed via disc diffusion and microdilution culture assays using the Calgary biofilm device. 3. Proliferation, morphology, collagen, and calcium production by primary bovine osteoblasts cultured upon antibiotic sol-gel surfaces were examined, and cytotoxicity evaluated using Alamar blue staining and lactate dehydrogenase assays. Concentrations of silica, calcium and phosphorus compounds within the cell layer cultured on sol-gel coatings and concentrations eluted into media, were quantified using ICP-OES. Furthermore, cellular phenotype was assessed using alkaline phosphatase activity with time in culture. Results. Low antibiotic concentrations within sol-gel had an inhibitory effect on clinically relevant biofilm growth, for example 0.8 mg ml. -1. tobramycin inhibited clinically isolated S. aureus (MRSA) growth with an 8-log reduction in viable colony forming units. There was no significant difference in metabolic activity between untreated and sol-gel exposed primary bovine osteoblasts in elution-based assays. Reduction (2-fold) in metabolic activity in direct contact assays after 48 hours exposure was likely to be due to increased osteoinduction, whereas no impact upon cell proliferation were observed (p=0.92 at 14 days culture). The morphology of primary osteoblasts was unaffected by culture on sol-gel coatings and collagen production was maintained. Calcium containing nodule production within bovine osteoblastic cells was increased 16-fold after 14 days culture upon sol-gel. Conclusions. The ultrathin sol-gel coating showed low cytotoxicity, strong biofilm reducing activity and antimicrobial activity, which was comparable to antibiotics alone, demonstrating that sol-gel delivery of antibiotics could provide local antimicrobial effects to inhibit PJI growth without the need for bone cement. Future work will develop and evaluate sol-gel performance in an ex vivo explant bone infection model which will reduce the need for animal experimentation

Aim. There 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. Method. In 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. Results. Between 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. Conclusions. The 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 words. orthopaedic surgery, unwanted events, revision rate

Background. Postoperative dislocation is one of the main surgical complications and the primary cause for revision surgery after 2-stage implant exchange due to periprosthetic infection of a total hip arthroplasty. Objective. The aims of our study were (1) to determine the incidence of dislocation after two-stage THA reimplantation without spacer placement, (2) to evaluate relevant risk factors for dislocation and (3) to assess the final functional outcome of those patients. Method. We prospectively analyzed 187 patients who underwent a two-stage total hip arthroplasty (THA) revision after being diagnosed with periprosthetic joint infection (PJI) from 2013 to 2019. The mean duration of follow-up was 54.2 ± 24.9 months (>36 months). The incidence of postoperative dislocation and subsequent revision was estimated through Kaplan-Meier curves and potential risk factors were identified using Cox hazard regression. The functional outcome of the patients was assessed using the modified Harris Hip Score (mHHS). Results. The estimated cumulative dislocation-free survival was 87.2% (95% CI: 81.2%-91.3%) with an estimated 10% and 12% risk for dislocation within the first 6 and 12 months, respectively. The use of a dual-mobility construct had no significant impact on the dislocation rate. Increasing body mass index (BMI) (HR=1.11, 95% CI: 1.02-1.19, p=0.011), abductor mechanism impairment (HR=2.85, 95% CI: 1.01-8.01, p=0.047), the extent of elongation of the affected extremity between stages (HR=1.04, 95% CI: 1.01-1.07, p=0.017), the final leg length discrepancy (HR=1.04, 95% CI: 1.01-1.08, p=0.018) and PJI recurrence (HR=2.76, 95% CI: 1.00-7.62, p=0.049) were found to be significant risk factors for dislocation. Overall revision rates were 17% after THA reimplantation. Dislocated hips were 62% more likely to undergo re-revision surgery (p<0.001, Log-rank= 78.05). A significant average increase of 30 points in mHHS scores after second-stage reimplantation (p=0.001, Wilcoxon-rank) was recorded, but no difference was noted in the final HHS measurements between stable and dislocated hips. Conclusion. Dislocation rates after 2-stage THA reimplantation for PJI remain high, especially regarding overweight or re-infected patients. Careful leg length restoration and an intact abductor mechanism seem critical to ensure stability in these complex patients

Aim. Antibiotic prophylaxis is central in preventing postoperative spine infections, yet knowledge of clinical spine tissue antibiotic concentrations remains limited. Pooled postoperative spine infection rates are constant (approximately 3%), resulting in severe patient morbidity, mortality, and prolonged hospitalization. Current antibiotic dosing regimens often involve fixed doses based on empirical knowledge, surrogate measures (plasma samples), non-clinical evidence (experimental models), and inferior methodology (tissue specimens). Therefore, personalized antibiotic dosing may be the future of antibiotic prophylaxis to prevent postoperative infections, especially implant infections. The aim was to continuously evaluate intra- and postoperative cefuroxime target spine tissue concentrations in long-lasting spine surgery after personalized dosing by repeated weight-dosed intravenous administrations. Method. Twenty patients (15 female, 5 male) scheduled for long-lasting spine deformity surgery with hypotensive anaesthesia were included; median age (range): 17.5 years (12-74), mean BMI (range): 22.2 (16.2-37.7), and mean surgery time (range): 4h 49min (3h 57min-6h 9min). Weight-dosed cefuroxime (20 mg/kg) was administered intravenously to all patients on average 25 min before incision and repeated after 4 hours. Microdialysis catheters were placed for sampling of cefuroxime concentrations in vertebral bone (only intraoperative sampling), paravertebral muscle, and subcutaneous tissue as soon as possible after surgery start. Upon wound closure, two additional catheters were placed in the profound and superficial part of the wound. Microdialysis and plasma samples were obtained continuously intra- and postoperative for up to 12 hours. The primary endpoint was (based on cefuroxime time-dependent efficacy) the time with cefuroxime concentrations above the clinical breakpoint minimal inhibitory concentration for Staphylococcus aureus of 4 µg/mL in percentage (%fT>MIC4) of. (a). patients’ individual surgery time,. (b). first dosing interval (0-4 hours),. (c). second dosing interval (4-12 hours). Results. Mean cefuroxime %fT>MIC4 (range) of:. (a). patients’ individual surgery time was 100% (100-100%) in all investigated tissues. (b). the first dosing interval was 93% (93-93%) in vertebral bone, paravertebral muscle, subcutaneous tissue, and 99% (99-100%) in plasma. (c). the second dosing interval was 87% (52-100%) in paravertebral muscle, 89% (52-100%) in subcutaneous tissue, 91% (71-100%) in the profound wound, 94% (72-100%) in the superficial wound, and 71% (42-100%) in plasma. Conclusions. Personalized cefuroxime dosing by repeated weight-dosed (20 mg/kg) intravenous administrations provided homogenous and therapeutic spine tissue exposure across all investigated tissues and plasma in long-lasting spine surgery with hypotensive anaesthesia (up to 11 hours). Thus, personalized cefuroxime dosing may decrease the risk of postoperative spine infection, especially in cases with implant insertion

Aim. Swedish guidelines on antibiotic prophylaxis in arthroplasty surgery recommend cloxacillin in fixed doses that pay little attention to the patient's renal function and weight. Nevertheless, there are no studies on whether the resulting free prophylactic cloxacillin in vivo concentrations are optimal. We aimed to evaluate whether the current recommended prophylactic dosage of cloxacillin is adequate. Method. We performed a prospective two-centre study, measuring the free (active) cloxacillin concentrations in plasma throughout surgery, in patients subject to primary hip and knee prosthetic joint replacements, aiming at 100 patients per centre. To account for plasma-bone exposure differences, concentrations were considered adequate if twice the epidemiological cut-off value for cloxacillin concerning wild type Staphylococcus aureus whereas two-three times were labelled threshold values. The two enrolling hospitals are acute care hospitals in central Sweden, also performing 600 - 1200 primary hip and knee joint arthroplasties annually. All patients scheduled for elective primary hip or knee replacements from January 2022 to April 2024 were eligible for participation. Exclusion criteria were allergy towards penicillins, cognitive disorders leading to inability to sign informed consent, and an absence of interpreter in case of a patient not speaking Swedish or English. Results. We present results from the first 49 patients included. Four patients had free cloxacillin concentrations below cut-off (8.2%). These four cases had prolonged surgeries of 77-100 minutes. An additional 5/49 (10.2%) had threshold values. Conversely 5/49 (10.2%) cases had concentrations exceeding 15 times the needed. No cases with threshold or low cloxacillin concentrations were attributable to a lack of concerning timing and dosing of cloxacillin. All concentrations were above or equal to our cut-off at the start of surgery. Eighteen percent of patients were of normal of weight (BMI 18.5- 25). Of the rest 4% were morbidly obese (BMI >40), 41% obese (BMI 30-40) and 37% overweight (BMI 25-30). Twenty seven percent (43/159) had diabetes and 45% suffered cardiac disease. Conclusions. Some patients in our cohort had insufficient active cloxacillin levels at the end of prosthetic joint surgery. Previous studies indicate that insufficient prophylactic antibiotic concentrations might lead to an enhanced risk of prosthetic joint infections. Other patients were massively overdosed, leading to unnecessary ecological effects and potentially adverse reactions. As inadequate cloxacillin concentrations were not associated with a lack of compliance to current guidelines a change in practise might be needed. Our final results may help to determine how dosing should be adjusted

Aim. This study aimed to evaluate the impact of intraoperative direct sonication on the yield of traditional culture and the time to positivity (TTP) of cultures obtained for periprosthetic joint infection (PJI), thereby assessing its potential to improve diagnostic efficiency and reduce contamination risk. Method. A prospective cohort study was conducted at a tertiary care center, involving 190 patients undergoing revision surgery for PJI from August 2021 to January 2024. Patients were included based on the 2018 International Consensus Meeting definition of PJI. The study utilized a novel sonication protocol, which involved direct intraoperative sonication of the implant and tissue, followed by incubation in a BACT/ALERT 3D system. The primary outcomes measured were the number and percentage of positive culture samples, identified microorganisms, and the TTP of each culture. Statistical analysis was performed using R software, with various tests applied to assess the significance of findings. Results. The study included 510 positive cultures from 190 patients, demonstrating that sonication significantly improved the positivity rate for both tissue and prosthesis specimens (p < 0.05). The median TTP for all samples was 3.13 days, with sonicated samples showing a significantly shorter TTP compared to non-sonicated samples (p < 0.05). Specifically, the shortest median TTP was observed in prosthesis post-sonication samples. Furthermore, the study found that Gram-positive organisms had a shorter TTP than gram-negative organisms, and specific microorganisms like Staphylococcus aureus and MRSE showed the fastest TTP. The analysis also revealed higher positivity rates in chronic PJIs compared to acute PJIs for sonicated tissue samples. Conclusions. The study demonstrates that intraoperative direct sonication combined with the BACT/ALERT 3D system can significantly enhance the diagnostic yield of cultures and reduce the TTP for common PJI pathogens. This novel technique not only improves pathogen detection, facilitating the tailoring of antibiotic therapy, but also potentially reduces the risk of contamination associated with sonication. These findings suggest that direct intraoperative sonication could be a valuable addition to the current diagnostic protocols for PJI, contributing to more effective management and treatment of this complex condition. Further research is necessary to explore the clinical significance of TTP and its correlation with patient outcomes in PJI

Aim. A substantial portion of periprosthetic joint infections (PJI) literature is comprised of observational studies. The Strengthening the Reporting of Observational Studies in Epidemiology guidelines emphasize the importance of clearly defining variables and providing diagnostic criteria. Well-defined variables in these studies play a crucial role in ensuring data consistency, fostering comparability among studies, and laying a robust foundation for evidence-based decision-making. We aimed to determine the definition of these variables and determine the objectivity of the definitions. Method. We reviewed observational studies on hip or knee PJI that focused on variables and their association with treatment outcomes. The inclusion criteria comprised studies from Jan 2017 to Jan 2023. We focused on 13 variables that were possibly subjective. These were smoking, alcohol use, diabetes mellitus, hypertension, lung disease, rheumatoid arthritis, liver diseases, kidney diseases, cardiovascular diseases, malignancy, immunosuppression, use of antibiotics, and type of infection. The reviewers examined the text of the articles, along with any available online supplements or protocols, for definitions of the selected variables. We classified a definition as objective if there was the presence of time element, severity, staging, frequencies, laboratory cut-off, medication dependence, among others. Chart review was deemed subjective. Results. We included 75 studies in the analysis. The most common factors studied were diabetes mellitus (79%), cardiovascular disease, smoking history, and rheumatoid arthritis (47% each). The variables that were objectively defined most often were antibiotic use (100%) and type of infection (95%). Smoking history (16%) and alcohol use (20%) were the least frequently objectively defined variables. Further analysis revealed that a considerable number of studies incorporated variables into their primary analyses without clear definitions. For instance, out of the 59 studies where diabetes was considered a variable, 41 studies (70%) included diabetes in their main analyses as a factor for PJI treatment outcomes, despite only 34 studies having defined this variable. Moreover, of the 34 provided definitions of diabetes mellitus, only 12 provided objective criteria for diagnosis. The rest of the provided definitions relied on “chart review” without further specification. Table 1 outlines the proportion of studies with variables defined and included in their analysis. Conclusions. Study variables were not clearly defined in most of the observational studies raising concerns about the reproducibility and reliability of findings. Our study underscores the vital need for standardized variable definitions in PJI research. Professional societies may play a crucial role in setting standards for the definition of variables. For any tables or figures, please contact the authors directly

Aim. To report outcomes of soft tissue reconstruction using free tissue transfer for the treatment of tibial osteomyelitis as part of a single-stage, ortho-plastic procedure. Method. Patients who underwent ortho-plastic reconstructive surgery to excise tibial osteomyelitis in combination with free tissue transfer in one stage were included. Patients underwent surgery between 2015 and 2024 in a single specialist centre within the UK. Baseline patient information, demographics, and infection information was recorded. Adverse outcomes were defined as (i) flap salvage required, (ii) flap failure and (iii) recurrence of infection. Patient reported quality of life was measured using the EuroQol EQ-5D-5L index score. Pre-operative QoL was compared to QoL at 1 year with a control group of 53 similar patients who underwent surgical treatment for tibial osteomyelitis without a free flap (local flap or primary closure). Results. Ninety-three patients were eligible for inclusion, with a mean age of 52 years (range 18–90). 77/93 (82.8%) had a free muscle flap with the remainder (17.2%) receiving a fasciocutaneous flap. The donor tissue was defined as 57 gracilis, 6 latissimus dorsi, 14 hemi-latissimus dorsi, and 16 anterolateral thigh. The recipient area of the tibia was distal 1/3 in 52 cases, middle 1/3 in 27 cases and proximal 1/3 in 12 cases. The average flap ischaemic time was 70 minutes (range 28 to 125). Seven patients (7.5%) required urgent flap salvage at a median time of 1.0 day (range 0.5 – 4.0). Of these, 4 (4.3%) went on to have total flap failure, of which 2 patients underwent below knee amputation subsequently. Flap failure was due to either arterial (n=2) or venous (n=2) anastomotic thrombus. There were 3 (3.2%) episodes of confirmed infection recurrence within the first year after the index procedure. EQ-index scores at 1-year post-operatively were significantly improved when compared to pre-operative scores (p=0.008). At 1-year post-operatively, EQ-index scores in patients who underwent free flap was similar compared to local flaps (p=0.410) and in those who underwent primary closure for tibial osteomyelitis (p=0.070). Conclusions. Microsurgical single stage surgery can achieve high flap survival rate (95.7%). Free flaps fail early due to anastomotic thrombus with no late failures seen. Free tissue transfer does not appear to give inferior QoL compared to matched patients with local flaps or direct closure in tibial osteomyelitis

Aim. Periprosthetic joint infection (PJI) is a severe complication after total joint arthroplasty. To prevent PJI, strict infection prevention measures are followed in combination with surgical antibiotic prophylaxis (SAP). To date, scientific reports concerning the optimal duration of SAP in revision arthroplasty are scarce. The aim of this multicenter open-label, randomized controlled trial in the Netherlands, is to investigate the superiority of 5 days (extended) versus a single dose of cefazolin to prevent PJI within the first year after revision arthroplasty of the hip and knee. Method. Included patients with an assumed aseptic hip or knee revision procedure received a single dose of 2 or 3 gram cefazolin preoperatively. Patients were randomly assigned in a 1:1 ratio to receive extended prophylaxis of cefazolin during 5 days postoperatively versus no prophylaxis after wound closure. Patients were excluded if evidence of PJI at revision. The primary endpoint was the incidence of PJI within one year after revision arthroplasty. PJI was defined according to the 2018 Philadelphia consensus criteria. With a sample size of 746 patients, an alpha of 5% and a power of 80%, superiority of the extended regimen would be shown if the lower boundary of the 95% confidence interval (CI) of the absolute between-group difference of the percentage of PJI is below −4%. Results. In total 751 patients were included for analysis: 379 in the single dose cefazolin group and 372 in the extended group. Within one year, PJI occurred in 2.6% (10/379) in the single dose group and 2.4% (9/372) in the extended group (risk difference, −0.2 percentage points; 95% CI, −2.5 to 2.0%), thus superiority was not shown. Adverse drug events were seen in 20 cases with extended and 7 cases with a single dose prophylaxis. Conclusions. Extended prophylaxis is not significantly superior to a single dose of cefazolin to prevent PJI within the first year after revision arthroplasty of the hip or knee. This is the first randomized controlled trail in which the duration of SAP in the selected group of patients undergoing revision arthroplasty was studied. Extending SAP after closure of the wound could increase the selection or induction of antimicrobial resistance, has an increased risk for adverse drug events, and is therefore not in line with the primary goal of antimicrobial stewardship, comprising optimizing clinical outcomes and ensuring cost-effective therapy while minimizing unintended consequences of antimicrobial use

Aim. Megaprosthesis have become a standard option in limb preserving surgery after bone resection in musculoskeletal tumors. Recently they have also been used in complex revision arthroplasty in cases with massive bone loss. The aim of this study was to analyze the incidence of periprosthetic joint infection (PJI) both in primary oncology cases and aseptic revision cases and analyze which are the significant risk factors for PJI with a special interest on the use of prophylactic antibiotic loaded calcium sulfate beads. Method. All patients undergoing surgery with the use of megaprosthesis in our institution between January/2012 and December/2022 were retrospectively reviewed. Data was collected from electronic medical records. We identified 108 procedures involving megaprosthesis in 90 patients with an average follow-up of 37 months. Indications were 79 primary musculoskeletal tumors and 29 aseptic complex revision arthroplasty. Results. Table 1 shows relevant clinical information. No significant risk factor was found either in uni or multivariate analysis. PJI rate was 15% (12/79) for primary musculoskeletal surgery and 31% (9/29) for complex revision surgery. The use of antibiotic loaded calcium sulfate beads did not show an advantage – 22% (9/41) with vs. 18% (12/67) without. Conclusions. In this relatively small series it was not possible to show a significal association between PJI and certain known risk factors such as gender, ASA score, site of surgery (knee) and revision surgery. The use of antibiotic loaded calcium sulfate beads as prophylaxis was not beneficial in reducing PJI rates in our cohort. We acknowledge the limitations of our study: a small sample group, in a single institution with heterogeneity in terms of diagnosis and surgical site. We recognize the need for a multicentric study with a larger cohort to validate these findings. For any tables or figures, please contact the authors directly

Aim. Rifampicin and fluoroquinolone based therapy is generally considered as first-choice targeted oral antimicrobial therapy for staphylococcal prosthetic joint infections (PJI) treated with debridement, antibiotics and implant retention (DAIR). Alternative equally effective antimicrobial strategies are urgently needed due to toxicity and drug-drug interactions that frequently occur with this strategy. Data from recent clinical studies suggests equipoise for other antimicrobial treatment regimens. The objective of the Rifampicin Combination Therapy versus Targeted Antimicrobial Monotherapy in the Oral Antimicrobial Treatment Phase of Staphylococcal Prosthetic Joint Infection (RiCOTTA)-trial is to evaluate whether monotherapy with clindamycin is non-inferior to rifampicin/fluoroquinolone combination therapy in patients with staphylococcal PJI that are treated with DAIR. Method. The RiCOTTA-trial is a multicenter, non-inferiority, open-label, randomized controlled trial evaluating clindamycin versus rifampicin/fluoroquinolone combination therapy in the oral treatment phase in patients with staphylococcal PJI managed with DAIR. The trial is performed in 16 hospitals in the Netherlands. Eligible patients are adults with staphylococcal knee or hip PJI managed by DAIR. Patients are included one to six days before antibiotic treatment is switched from intravenous to oral therapy. Patients with a contraindication for rifampicin, with a megaprosthesis or who receive intravenous antibiotics for more than three weeks after initial debridement are excluded. Primary outcome is treatment success one year after finishing antimicrobial treatment. Success is defined as the absence of: i. Infection related re-surgery, ii. New episode of antibiotic treatment for infection of the index joint after the initial treatment phase of 12 weeks, iii. Ongoing use of antibiotics for the index joint at the end of follow-up, iv. Death. The estimated treatment success of rifampicin combination therapy is 85% and the monotherapy strategy is considered not inferior when the difference in treatment success will be less than 10%. Enrolment of 158 patients per group (316 in total) is needed to confirm non-inferiority of monotherapy with a power of 80%. The trial is currently open for enrolment. The study is approved by the Medical Ethics Committee Leiden, the Hague, Delft, the Netherlands and registered under EU trial number 2022-501620-26-00 in Clinical Trial Information System. Conclusions. Currently, the RiCOTTTA study is the largest randomised clinical trial that compares targeted oral monotherapy with rifampicin combination treatment for staphylococcal PJI. Noninferiority of monotherapy would result in a change in national PJI guidelines and enable clinicians to use a more patient-tailored approach when considering antibiotics for patients during the oral treatment phase of PJI

Aim. There is controversy regarding the use of Antibiotic-loaded cement (ALBC) as compared to non-antibiotic-loaded cement (NALBC) to reduce the overall infection rate without affecting implant survival or adding additional risks on fixation for primary total knee arthroplasty (TKA). Method. To conduct the analysis, we utilized the Catalan Arthroplasty Registry (RACat) for the TKAs implanted between 2005 and 2017. The primary variable recorded was the use of cement with or without antibiotics. Other recorded variables included were age, sex, diabetes mellitus, obesity, Charlson index and type of hospital. We analyzed the effect of ALBC vs. NALBC in reducing the risk of prosthetic infection at 3, 6, 12, and 24 months as well as prosthetic survival due to mechanical causes at 1, 5, and 10 years. Univariate and multivariable analyses of risk factors were conducted. Thereby, an interactive predictive model that determines the risk of prosthetic infection based on each patient's characteristics was created. Results. A total of 28,287 TKAs from the RACat were analyzed. In that total, there were 19,788 NALBC and 8,499 ALBC. The infection rates for TKAs with NALBC vs. those with ALBC at 3, 6, 12, and 24 months were respectively: 1.69% vs. 1.39% (p=0.132); 1.81% vs. 1.56% (p=0.147); 2.14% vs. 1.73% (p=0.030); 2.51% vs. 1.86% (p=0.001). A statistically significant reduction in periprosthetic infection rate was observed in the ALBC group at 12 and 24 months. No differences were observed between the two groups in terms of prosthetic mechanical survival. Being younger, male and having had previous knee surgery or having a high comorbidity index all led to a higher risk of prosthetic revision due to infection. Conclusions. The use of ALBC as a fixation method for TKA leads to a reduction in the risk of prosthetic infection without altering the mechanical survival of the implant. The creation of a predictive model helps determine the individualized risk of prosthetic infection based on the patient's characteristics

Aim. dalbavancin, a lipo-glycopeptide antibiotic effective against Gram-positive bacteria (including methicillin-resistant Staphylococcus aureus), allows extended dosing interval due to its peculiar pharmacokinetics. Despite being registered for treatment of acute skin infections, off-label use has shown promise in various settings, particularly in osteo-articular infections. This study aims to assess dalbavancin's pharmacological efficacy and its safety and clinical success in patients treated according to personalized schedules guided by Therapeutic Drug Monitoring (TDM), particularly in long-term therapies. Methods. non-interventional, retrospective, single-center pharmacological study. We included adult patients with at least one dalbavancin TDM determination from July 1, 2022 to February 1, 2024 and treated with outpatient parenteral antimicrobial therapy. We recorded dalbavancin trough concentration (Cmin) and its peak concentration (Cmax) and employed log-linear regression models to predict the timing of dalbavancin dosing, aiming to sustain Cmin levels above 4 or 8.04 mg/L, according to recent literature. Data regarding index infections, patients’ characteristics, outcomes, and adverse events were also collected. Results. we included 32 patients, whose clinical and microbiological characteristics are depicted in Table 1. Regarding the primary outcome, 132/134 (98.5%) trough concentration was >4 mg/L, while 112/134 (83.6%) was >8.04 mg/L. For the secondary outcomes, 2/32 patients experienced an adverse event correlated to dalbavancin: (i) exanthema one week after the start of therapy and (ii) exanthema, conjunctivitis, angioedema, and nausea one month after the start of therapy. Moreover, we observed 4/32 clinical unsuccess (one failure during treatment, one relapse after the end of therapy, one switch to another antibiotic, and one isolation of non-susceptible microorganism). Conclusions. a TDM-based approach with the use of a log-linear regression model allows a more precise timing of dalbavancin administration by maintaining sufficient concentration of circulating drugs. This approach is promising for infections requiring a long-term treatment, such as orthopedic infection where source control is not possible. For any tables or figures, please contact the authors directly

Aim. The intention of suppressive antimicrobial therapy (SAT) for prosthetic joint infection (PJI) is to minimise symptoms, maintain function and prevent further surgery in patients who cannot undergo further attempts at curative treatment(1). There is little high-quality evidence examining the role and efficacy of SAT for patients with PJI(1,2). The objective of this study was to describe the use of and outcomes after SAT in a large prospective PJI cohort. Methods. A pre-planned analysis of a prospective multi-centre cohort of patients with PJI. SAT was defined as antimicrobial therapy for PJI continuing 12-months after diagnosis or where there was an intention for chronic suppressive antibiotics. The primary outcome was treatment failure at 24 months, defined as any of the development of PJI symptoms, further surgery or death from PJI. Secondary outcomes included Oxford Hip and Knee Scores. Results. SAT was prescribed for 223 (31.0%) of the PJI cohort. Patients prescribed SAT for PJI were more likely to be older, have comorbidities, chronic PJI, higher CRP, a sinus tract and be treated with retention of their prosthesis than those not prescribed SAT. At 24-months, treatment failure was more common in the SAT group 75/185(40.1%) compared with the non-SAT group 85/447(19.0%). Propensity score adjusted analysis did not demonstrate an association between SAT and treatment failure in patients with chronic PJI (OR[95% CI] 1.57[0.63-3.91), late-acute PJI(1.87[0.90-3.87]), a sinus tract (2.74[0.89-8.39]), ongoing symptoms at day 90 (1.19[0.43-3.23]), treatment with DAIR(1.61[0.87-2.99]) or Staphylococcus aureus PJI (1.25[0.62-2.54]). There were similar improvements between SAT and non-SAT patients in functional joint scores (OHS median (IQR) +8.5(19.0) vs +7.0(22.0);p=0.78 and OKS +8.0(20.0) vs +7.0(22.0);p=0.53). Conclusion. SAT use for PJI is common. The lack of demonstrated evidence in this study for its benefit in controlling infection across multiple subgroups of patients but with some improvements in functional scores, suggest that the advantages of SAT are at best complex