It has been shown that the outcome of a DAIR (debridement, antimicrobial therapy, and implant retention) procedure depends on multiple factors (e.g. infection type, host factors, clinical presentation, condition of surrounding soft tissue, causing pathogen, surgical technique, antimicrobial therapy); therefore, adequate patient selection is key for DAIR success. In this position paper, we discuss the most relevant factors influencing the outcome and define indications, contraindications, and risk factors for a DAIR procedure based on the most robust and most recently published data. Furthermore, we discuss the surgical technique in combination with systemic antimicrobial therapy in patients undergoing a DAIR procedure. This position paper may help reduce reinfection rates as well as the physical, psychological, and economic burden associated with periprosthetic joint infection (PJI). We believe that a reasonable outcome can be achieved with careful patient selection, a dedicated multidisciplinary team, and an appropriate surgical technique and antimicrobial therapy.

Aims: It remains unclear if postoperative antibiotic (AB) treatment is advantageous in presumed aseptic revision arthroplasties of the hip (rTHA) and knee (rTKA) with unexpected positive intraoperative cultures (UPIC). The aim of this study is to evaluate if there is a difference in the re-revision rate in patients with UPIC when treated with postoperative AB or when postoperative AB is withheld. Methods: In this retrospective matched cohort study we compared the re-revision rates in rTHA and rTKA with (AB group: 45 rTHA, 25 rTKA) and without (non-AB group: 45 rTHA, 25 rTKA) AB treatment in patients with UPIC. Baseline covariates for matching were the microorganism (likely or not likely to be a contaminant), patient demographics, joint, revision type, surgical site infection score, American Society of Anesthesiologists classification, serum C-reactive protein (CRP). Results: After a median follow-up of 4.1 (inter-quartile range, IQR: 2.9–5.5) years after rTHA and rTKA, the re-revision rate between the AB group and the non-AB group was 14.3 % versus 15.7 % (P=0.81). In the AB group, 4.3 % (3/70) of patients underwent revision due to septic complications compared to 5.7 % (4/70) in the non-AB group (P=0.69). None of the patients were diagnosed with a confirmed periprosthetic joint infection (PJI) according to the PJI diagnostic criteria of European Bone and Joint Infection Society (EBJIS). In 22/70 (31.4 %) of the patients in the AB group and in 15/70 (21.4 %) of the patients in the non-AB group, a diagnosis of “infection likely” was made according to the EBJIS criteria (P=0.18). All UPICs with low virulent microorganisms were considered to be contamination (coagulase-negative Staphylococci; Corynebacterium; anaerobic Gram-positive bacilli and cocci, e.g., Finegoldia magna, Cutibacterium acnes). Conclusion: Postoperative AB treatment did not result in a decreased re-revision rate in patients with UPIC in presumed aseptic rTHA and rTKA. Patients diagnosed with pathogens classified as a likely contaminant can be safely ignored.

Importance Fracture-related infection (FRI) is a serious complication following fracture fixation surgery. Current treatment of FRIs entails debridement and 6 weeks of intravenous (IV) antibiotics. Lab data and retrospective clinical studies support use of oral antibiotics, which are less expensive and may have fewer complications than IV antibiotics. Objective To evaluate the effectiveness of treatment of FRI with oral vs IV antibiotics. Design, Setting, and Participants The POvIV multicenter, prospective randomized clinical trial was conducted across 24 trauma centers in the US among patients aged 18 to 84 years who had fracture repair or arthrodesis with fixation with implants and developed an FRI without radiographic evidence of osteomyelitis. Patients were enrolled between March 2013 and September 2018 and followed up for 12 months after hospitalization for treatment of their FRI. Intervention Oral vs IV antibiotics following FRI. Main Outcomes and Measures The primary outcome was number of surgical interventions, and the primary hypothesis was noninferiority of oral vs IV antibiotics with respect to the number of study injury–related surgical interventions by 1 year. Unadjusted modified intent-to-treat (mITT) and adjusted per-protocol (PP) analyses were prespecified. A post hoc adjusted mITT analysis was conducted to resolve discrepancies between the results of the prespecified mITT and PP analyses. Recurrence of a deep surgical site infection was a key secondary outcome. Results Among 233 total patients, mean (SD) age was 46.0 (13.9) years, and 53 patients were female (22.7%). The mean number of surgical interventions within 1 year was 1.3 and 1.1 for the oral and IV groups, respectively. The upper bound of the 95% confidence interval of the mean difference with unadjusted mITT analysis was 0.59, which was lower than the prespecified noninferiority margin of 0.67, indicating noninferiority of oral to IV antibiotics. Adjusted PP analysis did not support noninferiority of the number of reoperations. A post hoc adjusted mITT analysis also showed noninferiority. The treatment effects estimates for the key secondary outcome of reinfection showed a similar pattern as those for the primary outcome. Conclusions and Relevance In this prospective randomized clinical trial, oral antibiotic treatment was noninferior to IV treatment with respect to the primary outcome of number of surgical interventions based on mITT analysis. However, there is some uncertainty in these findings based on preplanned and post hoc secondary analyses. A similar pattern of treatment effect estimates was observed for the secondary outcome of recurrence of infection.

Introduction There have been conflicting reports on the risk of periprosthetic joint infection (PJI) with the use of alternative antibiotics to cefazolin following arthroplasty. We leveraged recent data from a nationally representative multi-payer dataset to investigate this question. Methods We queried a healthcare dataset from 2016 to 2022 to identify primary total hip arthroplasties (THAs) using Current Procedural Terminology (CPT) and International Classification of Disease-Procedure Coding System (ICD-PCS) codes (27130, 0SR90xx, 0SRB0xx) with a corresponding osteoarthritis diagnosis (International Classification of Disease-Clinical Modification (ICD-CM): M16). Patient demographics, characteristics, and outcomes were extracted from existing dataset variables. The PJIs were defined using ICD-10 diagnosis codes from the Centers for Medicare & Medicaid Services’ procedure-specific complication measure within 90 days of surgery. We compared PJI between patients receiving cefazolin antibiotic prophylaxis and patients who received an alternative antibiotic or cefazolin plus another antibiotic. The association between cefazolin use and PJI was evaluated using multinomial logistic regression. This study included 289,369 primary THA patients from 2016 to 2022. There were 25,164 patients (8.7%) who received a non-cefazolin antibiotic, 200,367 (69.2%) received cefazolin only, and 63,838 (22.1%) received cefazolin plus an alternative antibiotic. Results In univariate analysis, there was a significant difference in the rate of 90-day PJI between the non-cefazolin group, cefazolin only, and cefazolin plus other antibiotic group (0.9, 0.5, and 0.5%, respectively, P < 0.001). In a logistic regression analysis that adjusted for age, sex, payer, race, ethnicity, and Elixhauser Comorbidity Index, the use of cefazolin only and cefazolin plus other antibiotic, were associated with reduced risk of 90-day PJI [OR (odds ratio) 0.62, 95% CI (confidence interval) (0.53 to 0.72), P < 0.001] and [OR 0.64, 95% CI (0.54 to 0.76), P < 0.001]. Conclusions In this nationally representative multi-payer study using recent data, patients who received antibiotic prophylaxis with cefazolin had lower 90-day rates of PJI compared to those receiving alternative antibiotics during primary total hip arthroplasty.

Spinal implant infections are a serious complications of instrumented spinal fusion surgeries, carrying high morbidity and complex management challenges. Early postoperative infections may manifest with wound-healing issues, back pain, and fevers. Magnetic resonance imaging (MRI) is the preferred imaging modality, but can be limited by metal artifacts. For cases with stable implants, surgical debridement with implant retention combined with at least 12 weeks of antibiotics is currently considered appropriate treatment. Staphylococcal infections are ideally treated with biofilm-active antibiotics. Suppressive antibiotic therapy can be considered when surgical debridement has been delayed or is incomplete, and for those who are poor surgical candidates for another surgery. Chronic infections may present insidiously with implant failure or pseudarthrosis; implant removal or revision is generally pursued. As current guidance is heavily based on the periprosthetic joint infection literature and low-level studies on spinal implant infections, further research on optimizing diagnostic and treatment approaches is needed.

Background Prosthetic joint infection (PJI) caused by Candida spp is a severe complication of arthroplasty. We investigated the outcomes of Candida PJI. Methods This was a retrospective observational multinational study including patients diagnosed with Candida-related PJI between 2010 and 2021. Treatment outcome was assessed at 2-year follow-up. Results A total of 269 patients were analyzed. Median age was 73.0 (interquartile range [IQR], 64.0–79.0) years; 46.5% of patients were male and 10.8% were immunosuppressed. Main infection sites were hip (53.0%) and knee (43.1%), and 33.8% patients had fistulas. Surgical procedures included debridement, antibiotics, and implant retention (DAIR) (35.7%), 1-stage exchange (28.3%), and 2-stage exchange (29.0%). Candida spp identified were Candida albicans (55.8%), Candida parapsilosis (29.4%), Candida glabrata (7.8%), and Candida tropicalis (5.6%). Coinfection with bacteria was found in 51.3% of cases. The primary antifungal agents prescribed were azoles (75.8%) and echinocandins (30.9%), administered for a median of 92.0 (IQR, 54.5–181.3) days. Cure was observed in 156 of 269 (58.0%) cases. Treatment failure was associated with age &gt;70 years (OR, 1.811 [95% confidence interval {CI}: 1.079–3.072]), and the use of DAIR (OR, 1.946 [95% CI: 1.157–3.285]). Candida parapsilosis infection was associated with better outcome (OR, 0.546 [95% CI: .305–.958]). Cure rates were significantly different between DAIR versus 1-stage exchange (46.9% vs 67.1%, P = .008) and DAIR versus 2-stage exchange (46.9% vs 69.2%, P = .003), but there was no difference comparing 1- to 2-stage exchanges (P = .777). Conclusions Candida PJI prognosis seems poor, with high rate of failure, which does not appear to be linked to immunosuppression, use of azoles, or treatment duration.

Abstract. In recent years, there has been a notable increase in research output on native vertebral osteomyelitis (NVO), coinciding with a rise in its incidence. However, clinical outcomes remain poor, due to frequent relapse and long-term sequelae. Additionally, the lack of a standardized definition and the use of various synonyms to describe this condition further complicate the clinical understanding and management of NVO. We propose a new framework to integrate the primary diagnostic tools at our disposal. These collectively fall into three main domains: clinical, radiological, and direct evidence. Moreover, they and can be divided into seven main categories: (a) clinical features, (b) inflammatory biomarkers, (c) imaging techniques, microbiologic evidence from (d) blood cultures and (e) invasive techniques, (f) histopathology, and (g) empirical evidence of improvement following the initiation of antimicrobial therapy. We provide a review on the evolution of these techniques, explaining why no single method is intrinsically sufficient to formulate an NVO diagnosis. Therefore, we argue for a consensus-driven, multi-domain approach to establish a comprehensive and universally accepted definition of NVO to enhance research comparability, reproducibility, and epidemiological tracking. Ongoing research effort is needed to refine these criteria further, emphasizing collaboration among experts through a Delphi method to achieve a standardized definition. This effort aims to streamline research, expedite accurate diagnoses, optimize diagnostic tools, and guide patient care effectively.

Background The optimal duration and choice of antibiotic for fracture-related infection (FRI) is not well defined. This study aimed to determine whether antibiotic duration (≤6 vs &gt;6 weeks) is associated with infection- and surgery-free survival. The secondary aim was to ascertain risk factors associated with surgery- and infection-free survival. Methods We performed a multicenter retrospective study of patients diagnosed with FRI between 2013 and 2022. The association between antibiotic duration and surgery- and infection-free survival was assessed by Cox proportional hazard models. Models were weighted by the inverse of the propensity score, calculated with a priori variables of hardware removal; infection due to Staphylococcus aureus, Staphylococcus lugdunensis, Pseudomonas or Candida species; and flap coverage. Multivariable Cox proportional hazard models were run with additional covariates including initial pathogen, need for flap, and hardware removal. Results Of 96 patients, 54 (56.3%) received ≤6 weeks of antibiotics and 42 (43.7%) received &gt;6 weeks. There was no association between longer antibiotic duration and surgery-free survival (hazard ratio [HR], 0.95; 95% CI, .65–1.38; P = .78) or infection-free survival (HR, 0.77; 95% CI, .30–1.96; P = .58). Negative culture was associated with increased hazard of reoperation or death (HR, 3.52; 95% CI, 1.99–6.20; P &lt; .001) and reinfection or death (HR, 3.71; 95% CI, 1.24–11.09; P &lt; .001). Need for flap coverage had an increased hazard of reoperation or death (HR, 3.24; 95% CI, 1.61–6.54; P = .001). Conclusions The ideal duration of antibiotics to treat FRI is unclear. In this multicenter study, there was no association between antibiotic treatment duration and surgery- or infection-free survival.

Background Pyogenic vertebral osteomyelitis (VO) represents a clinical challenge and is linked to substantial morbidity and mortality. This study aimed to examine mortality as well as potential risk factors contributing to in-hospital mortality among patients with VO. Methods This retrospective analysis involved patients receiving treatment for VO at University Regensburg in Germany from January 1, 2000, to December 3, 2020. It included in-hospital mortality rate, comorbidities and pathogens. Patients were identified using ICD-10 diagnosis codes: M46.2, M46.3, M46.4, and M46.5. Kaplan–Meier probability plots and odds ratios (OR) for mortality were calculated. Results Out of the total cohort of 155 patients with VO, 53 patients (34.1%) died during a mean follow-up time of 87.8 ± 70.8 months. The overall mortality was 17.2% at one year, 19.9% at two years and 28.3% at five years. Patients with congestive heart failure (p = 0.005), renal disease (p< 0.001), symptoms of paraplegia (p= 0.029), and sepsis (p = 0.006) demonstrated significantly higher overall mortality rates. In 56.1% of cases, pathogens were identified, with Staphylococcus aureus (S. aureus) and other unidentified pathogens being the most common. Renal disease (OR 1.85) and congestive heart failure (OR 1.52) were identified as significant risk factors. Conclusion Early assessment of the specific risk factors for each patient may prove beneficial in the management and treatment of VO to reduce the risk of mortality. These findings demonstrate the importance of close monitoring of VO patients with underlying chronic organ disease and early identification and treatment of sepsis. Prioritizing identification of the exact pathogens and antibiotic sensitivity testing can improve outcomes for patients in this high-risk group.

Abstract. The data on long-term antibiotic use following debridement, antibiotics, and implant retention (DAIR) for treatment of periprosthetic joint infections are limited. In this single-center retrospective study, we show that patients with eventual cessation of antibiotic suppression after DAIR had similar outcomes to those who remained on chronic antibiotic suppression.

Background Debridement, antibiotics, irrigation, and implant retention (DAIR) is the first-line management strategy for acute periprosthetic joint infections (PJI). Suppressive antibiotic therapy (SAT) after DAIR is proposed to improve outcomes, yet its efficacy remains under scrutiny. Methods We conducted a multicenter retrospective study in patients with acute PJI of the hip or knee and treated with DAIR in centers from Europe and the USA. We analyzed the effect of SAT using a Cox model landmarked at 12 weeks. The primary covariate of interest was SAT, which was analyzed as a time-varying covariate. Patients who experienced treatment failure or lost to follow-up within 12 weeks were excluded from the analysis. Results The study included 510 patients with 66 treatment failures with a median follow-up of 801 days. We did not find a statistically significant association between SAT and treatment failure (HR 1.37, 95% CI 0.79-2.39, p=0.27). Subgroup analyses for joint, country cohort, and type of infection (early or late acute) did not show benefit for SAT. Secondary analysis of country cohorts showed a trend toward benefit for the USA cohort (HR 0.36, 95% CI 0.11-1.15, p=0.09) which also had the highest risk of treatment failure. Conclusion The utility of routine SAT as a strategy for enhancing DAIR's success in acute PJI remains uncertain. Our results suggest that SAT's benefits might be restricted to specific groups of patients, underscoring the need for randomized controlled trials. Identifying patients most likely to benefit from SAT should be a priority in future studies.

Background Native joint septic arthritis (NJSA) is definitively diagnosed by a positive Gram stain or culture, along with supportive clinical findings. Preoperative antibiotics are known to alter synovial fluid cell count, Gram stain and culture results and are typically postponed until after arthrocentesis to optimize diagnostic accuracy. However, data on the impact of preoperative antibiotics on operative culture yield for NJSA diagnosis are limited. Methods We retrospectively reviewed adult cases of NJSA who underwent surgery at Mayo Clinic facilities from 2012-2021 to analyze the effect of preoperative antibiotics on operative culture yield through a paired analysis of preoperative culture (POC) and operative culture (OC) results using logistic regression and generalized estimating equations. Results Two hundred ninety-nine patients with NJSA affecting 321 joints were included. Among those receiving preoperative antibiotics, yield significantly decreased from 68.0% at POC to 57.1% at OC (p &lt; .001). In contrast, for patients without preoperative antibiotics there was a non-significant increase in yield from 60.9% at POC to 67.4% at OC (p = 0.244). In a logistic regression model for paired data, preoperative antibiotic exposure was more likely to decrease OC yield compared to non-exposure (OR = 2.12; 95% CI = 1.24-3.64; p = .006). Within the preoperative antibiotic group, additional antibiotic doses and earlier antibiotic initiation were associated with lower OC yield. Conclusion In patients with NJSA, preoperative antibiotic exposure resulted in a significant decrease in microbiologic yield of operative cultures as compared to patients in whom antibiotic therapy was held prior to obtaining operative cultures.

Introduction: The absence of a standardized postoperative antibiotic treatment approach for patients with surgically treated septic bursitis results in disparate practices. Methods: We retrospectively reviewed charts of adult patients with surgically treated septic olecranon bursitis at Mayo Clinic sites between 1 January 2000 and 20 August 2022, focusing on their clinical presentation, diagnostics, management, postoperative antibiotic use, and outcomes. Results: A total of 91 surgically treated patients were identified during the study period. Staphylococcus aureus was the most common pathogen (64 %). Following surgery, 92 % (84 of 91 patients) received systemic antibiotics. Excluding initial presentations of bacteremia or osteomyelitis (n=5), the median duration of postoperative antibiotics was 21 d (interquartile range, IQR: 14–29). Postoperative complications were observed in 23 % (21 of 91) of patients, while cure was achieved in 87 % (79 of 91). Active smokers had 4.53 times greater odds of clinical failure compared with nonsmokers (95 % confidence interval, 95 % CI: 1.04–20.50; p=0.026). The highest odds of clinical failure were noted in cases without postoperative antibiotic administration (odds ratio, OR: 7.4). Conversely, each additional day of antibiotic treatment, up to 21 d, was associated with a progressive decrease in the odds of clinical failure (OR: 1 at 21 d). Conclusion: The optimal duration of antibiotics postoperatively in this study was 21 d, which was associated with a 7.4-fold reduction in the odds clinical failure compared with cases without postoperative antibiotics. Further validation through a randomized controlled trial is needed.

Background: Periprosthetic joint infection is a devastating and severe complication of total knee arthroplasty (TKA). The Australian Joint Registry reports an increasing number of debridement, antibiotics, and implant retention (DAIR) procedures, underscoring the need to comprehend outcomes for informed treatment decisions. This study aimed to determine the outcome of DAIR procedures, evaluate time since primary TKA, and identify patient-related factors associated with DAIR failure. Methods: We conducted a national registry-based cohort study using data from 1999 to 2021. We included 8,642 revisions for infection, of which 5,178 were DAIR procedures (60%) predominantly performed within four weeks of primary surgery. We assessed the outcomes using Kaplan-Meier estimates and Cox proportional hazard models. Results: Post-DAIR, the cumulative percent second revision cumulative percent revision in the DAIR cohort was 20% at year 1, increasing to 36% at year 17. Early DAIR procedures had a lower post-DAIR revision rate until three months after primary TKA. A DAIR performed within 2 weeks after primary TKA compared to three months had an hazard ratio [HR]: 0.74 (95% CI [confidence interval]: 0.62 to 0.88). After four weeks, the post-DAIR revision rate did not deteriorate and was similar for further time periods from the primary. Men had an age-adjusted HR of 1.28 (95% CI: 1.14 to 1.43, P < 0.001) for DAIR failure compared to women. There was a significantly higher HR for post-DAIR revision in patients younger than 75 years of age, compared to patients aged ≥ 75 years. Conclusions: These findings underscore the critical influence of patient-related factors and the timing of DAIR treatment on the need for additional surgery. DAIR after four weeks had an increased risk of subsequent revision, and older women undergoing early DAIR interventions had more favorable outcomes. Understanding these nuances aids in optimizing periprosthetic joint infection management strategies, offering insights for decision-making.

Background: Early diagnosis and treatment of osteomyelitis is essential to prevent potential complications including sepsis, extensive bone resection, amputation, and death. Despite current treatment strategies for management of osteomyelitis, recurrence rates reported in the literature are upwards of 25 %. Current evidence comparing the efficacy of differing surgical treatments of osteomyelitis is inconclusive. The purpose of this study is to compare rates of re-debridement and amputation in patients who receive either debridement alone or debridement with placement of local antibiotic delivery systems as initial treatment for lower extremity long bone osteomyelitis. Methods: A retrospective cohort study was performed to investigate complication rates after surgical treatment methods for osteomyelitis of the femur and tibia. The rates of re-debridement and amputation were compared in patients who received either debridement alone or debridement with placement of local antibiotic delivery systems. Results: This study reports 73 % lower rates of re-debridement after debridement and local antibiotic delivery in tibial osteomyelitis, and 83 % lower rates of re-debridement after debridement and placement of local antibiotic delivery systems in femoral osteomyelitis compared to debridement alone. There was no significant difference in amputation rates between treatment groups for either tibial (7.4 vs 5.7 %; OR: 1.31; 95 % CI, 0.92-1.87) or femoral osteomyelitis (2.4 vs 1.4 %; OR: 1.65; 95 % CI, 0.71-4.01). Conclusion: There was a significantly decreased likelihood of re-debridement for patients who underwent initial treatment with combined debridement and placement of antibiotic delivery systems compared to debridement alone. Providers may consider this when comparing treatment options for their patients with lower extremity osteomyelitis.

Background: Studies evaluating surgical-site infection have had conflicting results with respect to the use of alcohol solutions containing iodine povacrylex or chlorhexidine gluconate as skin antisepsis before surgery to repair a fractured limb (i.e., an extremity fracture). Methods: In a cluster-randomized, crossover trial at 25 hospitals in the United States and Canada, we randomly assigned hospitals to use a solution of 0.7% iodine povacrylex in 74% isopropyl alcohol (iodine group) or 2% chlorhexidine gluconate in 70% isopropyl alcohol (chlorhexidine group) as preoperative antisepsis for surgical procedures to repair extremity fractures. Every 2 months, the hospitals alternated interventions. Separate populations of patients with either open or closed fractures were enrolled and included in the analysis. The primary outcome was surgical-site infection, which included superficial incisional infection within 30 days or deep incisional or organ-space infection within 90 days. The secondary outcome was unplanned reoperation for fracture-healing complications. Results: A total of 6785 patients with a closed fracture and 1700 patients with an open fracture were included in the trial. In the closed-fracture population, surgical-site infection occurred in 77 patients (2.4%) in the iodine group and in 108 patients (3.3%) in the chlorhexidine group (odds ratio, 0.74; 95% confidence interval [CI], 0.55 to 1.00; P = 0.049). In the open-fracture population, surgical-site infection occurred in 54 patients (6.5%) in the iodine group and in 60 patients (7.3%) in the chlorhexidine group (odd ratio, 0.86; 95% CI, 0.58 to 1.27; P = 0.45). The frequencies of unplanned reoperation, 1-year outcomes, and serious adverse events were similar in the two groups. Conclusions: Among patients with closed extremity fractures, skin antisepsis with iodine povacrylex in alcohol resulted in fewer surgical-site infections than antisepsis with chlorhexidine gluconate in alcohol. In patients with open fractures, the results were similar in the two groups. (Funded by the Patient-Centered Outcomes Research Institute and the Canadian Institutes of Health Research; PREPARE ClinicalTrials.gov number, NCT03523962.).

Background Need for parenteral administration and total duration of antibiotic therapy for prosthetic joint infection (PJI) are debated. We report our PJI management, in which outpatient care is privileged. Methods This was a retrospective multicentre cohort study of PJI managed from January 2017 to Jun 2021. Microbial diagnosis was based on surgical samples. Surgical procedures and antibiotic treatments were reported. Chronic PJI was defined by a course &gt;1 month. Oral antibiotic therapy (OAT) was defined by exclusive use of oral antibiotics or by ≤3 days of parenteral treatments. Management failure was defined by clinical and/or microbial relapse of PJI over 24 months after surgical treatment. Results One hundred and seventy-two patients from 13 institutions were included: 103 were male (60%) and mean age was (±SD): 73 ± 12 years. Sites for PJI were mainly hip (50%) and knee (35%), being chronic infections in 70 cases (41%). The main bacterial genus in monomicrobial infections was Staphylococcus spp. (60%). We recorded 41 (24%) implant exchanges. An OAT was prescribed in 76 cases (44%), and the median (range) course for parenteral route was 6 days (4–180) for 96 cases. Median (range) duration of antimicrobials was 42 days (21–180). Management failure was observed in 7/76 (9.2%) cases treated with OAT and 15/96 (15.6%) treated with prolonged parenteral therapy. In multivariate analysis, risk factors for failure were a knee PJI [adjusted OR (95% CI) = 3.27 (1.27–8.40)] and a polymicrobial infection [4.09 (1.46–11.49)]. Conclusions OAT for 6 weeks for PJI was associated with a low rate of management failure.

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.

Importance Despite the frequency of total knee arthroplasty (TKA) and clinical implications of prosthetic joint infections (PJIs), knowledge gaps remain concerning the incidence, microbiological study results, and factors associated with these infections. Objectives To identify the incidence rates, organisms isolated from microbiological studies, and patient and surgical factors of PJI occurring early, delayed, and late after primary TKA. Design, Setting, and Participants This cohort study obtained data from the US Department of Veterans Affairs (VA) Corporate Data Warehouse on patients who underwent elective primary TKA in the VA system between October 1, 1999, and September 30, 2019, and had at least 1 year of care in the VA prior to TKA. Patients who met these criteria were included in the overall cohort, and patients with linked Veterans Affairs Surgical Quality Improvement Program (VASQIP) data composed the VASQIP cohort. Data were analyzed between December 9, 2021, and September 18, 2023. Exposures Primary TKA as well as demographic, clinical, and perioperative factors. Main Outcomes and Measures Incident hospitalization with early, delayed, or late PJI. Incidence rate (events per 10 000 person-months) was measured in 3 postoperative periods: early (≤3 months), delayed (between >3 and ≤12 months), and late (>12 months). Unadjusted Poisson regression was used to estimate incidence rate ratios (IRRs) with 95% CIs of early and delayed PJI compared with late PJI. The frequency of organisms isolated from synovial or operative tissue culture results of PJIs during each postoperative period was identified. A piecewise exponential parametric survival model was used to estimate IRRs with 95% CIs associated with demographic and clinical factors in each postoperative period. Results The 79 367 patients (median (IQR) age of 65 (60-71) years) in the overall cohort who underwent primary TKA included 75 274 males (94.8%). A total of 1599 PJIs (2.0%) were identified. The incidence rate of PJI was higher in the early (26.8 [95% CI, 24.8-29.0] events per 10 000 person-months; IRR, 20.7 [95% CI, 18.5-23.1]) and delayed periods (5.4 [95% CI, 4.9-6.0] events per 10 000 person-months; IRR, 4.2 [95% CI, 3.7-4.8]) vs the late postoperative period (1.3 events per 10 000 person-months). Staphylococcus aureus was the most common organism isolated overall (489 [33.2%]); however, gram-negative infections were isolated in 15.4% (86) of early PJIs. In multivariable analyses, hepatitis C virus infection, peripheral artery disease, and autoimmune inflammatory arthritis were associated with PJI across all postoperative periods. Diabetes, chronic kidney disease, and obesity (body mass index of ≥30) were not associated factors. Other period-specific factors were identified. Conclusions and Relevance This cohort study found that incidence rates of PJIs were higher in the early and delayed vs late post-TKA period; there were differences in microbiological cultures and factors associated with each postoperative period. These findings have implications for postoperative antibiotic use, stratification of PJI risk according to postoperative time, and PJI risk factor modification.