Aim. Prosthetic joint infection (PJI) is a devastating and costly complication of total joint arthroplasty (TJA). Use of extended oral antibiotic prophylaxis (EOAP) has become increasingly popular in the United States following a highly publicized study (Inabathula et al) from a single center demonstrating a significant protective effect (81% reduction) against PJI in ‘high-risk’ patients. However, these results have not been reproduced elsewhere and EOAP use directly conflicts with current antibiotic stewardship efforts. In order to study the role of EOAP in PJI prevention, consensus is needed for what defines ‘high-risk’ patients. The revision TJA (rTJA) population is an appropriate group to study due to having a higher incidence of PJI. The purpose of the current study was to rigorously determine which preoperative conditions described by Inabathula et al. (referred to as Inabathula criteria (IBC)) confer a higher rate of PJI in patients undergoing aseptic rTJA. Method. 2,256 patients that underwent aseptic rTJA at a single high-volume institution between 2016–2022 were retrospectively reviewed. Patient demographics and comorbidities were recorded to determine if they had 1 or more ‘IBC’, a long list of preoperative conditions including autoimmune diseases, active smoking, body mass index (BMI)>35, diabetes mellitus, and chronic kidney disease (CKD). Reoperation for PJI at 90-days and 1-year was recorded. Chi-squared or Fischer's exact tests were calculated to determine the association between preoperative presence/absence of IBC and PJI. Multivariable logistic regressions were conducted to determine if specific comorbidities within the IBC individually conferred an increased PJI risk. Results. 1223 patients (54.2%) had at least one IBC condition. IBC-positive patients were more likely to be female, have an increased ASA score, and higher BMI. IBC-positive patients had a significant increase in PJI risk at both 90-days (relative risk (RR)=2.32, p<0.0001) and 1-year (RR=2.14, p=0.002) versus IBC-negative patients. Within IBC-positive patients, every additional IBC condition conferred a 1.8× odds increase for 90-day PJI (p<0.0001), and 1.76× odds increase in 1-year PJI (p<0.0001). Multivariable logistic regression identified active smoking, BMI>35, CKD, and diabetes mellitus as being independently associated with PJI development (p<0.05). Conclusions. Over half of rTJA patients meet IBC and could be eligible to receive EOAP in the United States. However, the specific presence of active smoking, BMI>35, CKD, and diabetes mellitus appear to be responsible for the increased risk of PJI. Prospective studies investigating EOAP use for patients with these specific conditions are urgently needed to prevent unnecessary antibiotic use

Aim. While metagenomic (microbial DNA) sequencing technologies can detect the presence of microbes in a clinical sample, it is unknown whether this signal represents dead or live organisms. Metatranscriptomics (sequencing of RNA) offers the potential to detect transcriptionally “active” organisms within a microbial community, and map expressed genes to functional pathways of interest (e.g. antibiotic resistance). We used this approach to evaluate the utility of metatrancriptomics to diagnose PJI and predict antibiotic resistance. Method. In this prospective study, samples were collected from 20 patients undergoing revision TJA (10 aseptic and 10 infected) and 10 primary TJA. Synovial fluid and peripheral blood samples were obtained at the time of surgery, as well as negative field controls (skin swabs, air swabs, sterile water). All samples were shipped to the laboratory for metatranscriptomic analysis. Following microbial RNA extraction and host analyte subtraction, metatranscriptomic sequencing was performed. Bioinformatic analyses were implemented prior to mapping against curated microbial sequence databases– to generate taxonomic expression profiles. Principle Coordinates Analysis (PCoA) and Partial Least Squares-Discriminant Analysis were utilized to ordinate metatranscriptomic profiles, using the 2018 definition of PJI as the gold-standard. Results. After RNA metatranscriptomic analysis, blinded PCoA modeling revealed accurate and distinct clustering of samples into 3 separate cohorts (infected, aseptic, and primary joints) – based on their active transcriptomic profile, both in synovial fluid and blood (synovial anosim p=0.001; blood anosim p=0.034). Differential metatranscriptomic signatures for infected versus noninfected cohorts enabled us to train machine learning algorithms to 84.9% predictive accuracy for infection. Multiple antibiotic resistance genes were expressed, with high concordance to conventional antibiotic sensitivity data. Conclusions. Our findings highlight the potential of metatranscriptomics for infection diagnosis. To our knowledge, this is the first report of RNA sequencing in the orthopaedic literature. Further work in larger patient cohorts will better inform deep learning approaches to improve accuracy, predictive power, and clinical utility of this technology

The number of Americans over the age of 80 is increasing at a faster rate than that of the 65–80 population. The cohort age 85–94 years had the fastest rate of growth from 2000–2010. The number of Americans older than 95 years grew at approximately 26% during the same period. This rapid growth has been associated with an increasing incidence of osteoarthritis of the hip and knee in this population. This surge in the growth rate of the elderly population has coincided with an increasing demand for primary and revision total joint arthroplasty. Surgeons need to be prepared to perform safely and appropriately these procedures in this rapidly growing segment of the population. Surgeons need to be aware of the 1) clinical outcomes that can be expected when total joint procedures are performed in this group of patients; 2) the morbidity and mortality associated with the performance of these procedures; and 3) the relative cost effectiveness of these interventions. Clinical outcomes of TJA in this population are generally good. Pain and satisfaction scores are similar to those of younger patients. Although pre-operative pain and functional impairment scores are higher pre-operatively in elderly patients, these improve significantly following TJA. However, functional outcome scores decline noticeably after 5 years, reflecting the impact of coexistent comorbidities. The continued need for assistive devices is greater in this age group than in younger total joint patients. The risk of falls, a particular issue of concern in this age group, is reduced after total hip and knee surgery. The rate of complications, including mortality, following TJA in this age group is greater than in the 65–79-year-old group. The use of hospitalists to co-manage peri-operative care is particularly important in this age group. The increased rate of complications is associated with longer lengths of stay. However, the length of stay for this age group after primary total joint replacement is decreasing significantly; reflecting the widespread streamlining of peri-operative care that is being incentivised and implemented nationwide. The use of extended care facilities is also greater in this age group. The performance of revision TJA in this age group is particularly challenging. The rates of revision in elderly patients are anticipated to rise significantly in coming years. Although revision TJA is associated with significant pain relief and patient satisfaction, it is accompanied by mortality and complication rates that are substantially greater than those in younger age groups

Aim. Hospital systems have recently instituted early systemic sepsis recognition systems, where vital signs and laboratory findings are monitored and automatically alert providers to potential sepsis. Although there are very few reports evaluating the use of sepsis alert systems outside of the emergency room or intensive care unit, many hospital systems have made the decision to apply the sepsis alarm protocols to all inpatients. The purpose of this study was to evaluate if an alarm system using systemic inflammatory response syndrome (SIRS) criteria is a valuable tool to predict systemic sepsis in the immediate postoperative period (POD#0–4) after total joint arthroplasty (TJA). Method. 10,791 primary and revision TJA patients at one institution, from 2010–2014, were retrospectively reviewed for positive SIRS criteria on each hospital day from the date of surgery to postoperative day four (POD#4). SIRS criteria included temperature > 38°C or < 36°C, heart rate > 90 beats per minute, respiratory rate > 20 breaths per minute, and white blood cell (WBC) > 12,000/mm3 or < 4,000/mm3. Additionally, hospital coding data was cross-referenced to identify patients who were diagnosed with systemic sepsis within 10 days after having a TJA. Results. Of the 10,791 patients undergoing a primary or revision TJA, only 1 patient was diagnosed with sepsis within 10 days of TJA, yielding a prevalence of 0.00009. During POD#0–4, 1798 patients would have triggered at least a 2 criteria SIRS alarm, yielding a false positive rate of 16.7% and a positive predictive value for systemic sepsis of 0.06% (95%CI: 0 to 0.31%). 416 patients would have triggered at least 3 criteria SIRS alarm, yielding a false positive rate of 3.9% and positive predictive value of 0.24% (95%CI:0.01 to 1.33%). The SIRS criteria in the one septic patient in this study did become positive, but did so only after the clinical team had already initiated sepsis care. Conclusions. A SIRS based alarm system for sepsis does not appear to have any utility in the postoperative period after TJA. We are concerned that the high false positive rate of these alarms may result in unnecessary sepsis work-ups, extended hospital stays, and potentially degrade the perceived importance of the sepsis alarms in other cohorts of hospital patients. Further research is necessary to determine if TJA patients with a length of stay greater than normal may benefit from an automatic sepsis alarm system