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

Aims. Although readmission has historically been of primary interest, emergency department (ED) visits are increasingly a point of focus and can serve as a potentially unnecessary gateway to readmission. This study aims to analyze the difference between primary and revision total joint arthroplasty (TJA) cases in terms of the rate and reasons associated with 90-day ED visits. Methods. We retrospectively reviewed all patients who underwent TJA from 2011 to 2021 at a single, large, tertiary urban institution. Patients were separated into two cohorts based on whether they underwent primary or revision TJA (rTJA). Outcomes of interest included ED visit within 90-days of surgery, as well as reasons for ED visit and readmission rate. Multivariable logistic regressions were performed to compare the two groups while accounting for all statistically significant demographic variables. Results. Overall, 28,033 patients were included, of whom 24,930 (89%) underwent primary and 3,103 (11%) underwent rTJA. The overall rate of 90-day ED visits was significantly lower for patients who underwent primary TJA in comparison to those who underwent rTJA (3.9% vs 7.0%; p < 0.001). Among those who presented to the ED, the readmission rate was statistically lower for patients who underwent primary TJA compared to rTJA (23.5% vs 32.1%; p < 0.001). Conclusion. ED visits present a significant burden to the healthcare system. Patients who undergo rTJA are more likely to present to the ED within 90 days following surgery compared to primary TJA patients. However, among patients in both cohorts who visited the ED, three-quarters did not require readmission. Future efforts should aim to develop cost-effective and patient-centred interventions that can aid in reducing preventable ED visits following TJA. Cite this article: Bone Jt Open 2022;3(7):543–548

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

Aims. Currently, the US Center for Medicaid and Medicare Services (CMS) has been testing bundled payments for revision total joint arthroplasty (TJA) through the Bundled Payment for Care Improvement (BPCI) programme. Under the BPCI, bundled payments for revision TJAs are defined on the basis of diagnosis-related groups (DRGs). However, these DRG-based bundled payment models may not be adequate to account appropriately for the varying case-complexity seen in revision TJAs. Methods. The 2008-2014 Medicare 5% Standard Analytical Files (SAF5) were used to identify patients undergoing revision TJA under DRG codes 466, 467, or 468. Generalized linear regression models were built to assess the independent marginal cost-impact of patient, procedural, and geographic characteristics on 90-day costs. Results. A total of 9,263 patients (DRG-466 = 838, DRG-467 = 4,573, and DRG-468 = 3,842) undergoing revision TJA from 2008 to 2014 were included in the study. Undergoing revision for a dislocation (+$1,221), periprosthetic fracture (+$4,454), and prosthetic joint infection (+$5,268) were associated with higher 90-day costs. Among comorbidities, malnutrition (+$10,927), chronic liver disease (+$3,894), congestive heart failure (+$3,292), anaemia (+$3,149), and coagulopathy (+$2,997) had the highest marginal cost-increase. The five US states with the highest 90-day costs were Alaska (+$14,751), Maryland (+$13,343), New York (+$7,428), Nevada (+$6,775), and California (+$6,731). Conclusion. Under the proposed DRG-based bundled payment methodology, surgeons would be reimbursed the same amount of money for revision TJAs, regardless of the indication (periprosthetic fracture, prosthetic joint infection, mechanical loosening) and/or patient complexity. Cite this article: Bone Joint J 2020;102-B(7):959–964

Introduction. Next generation sequencing (NGS) has been shown to facilitate detection of microbes in a clinical sample, particularly in the setting of culture-negative periprosthetic joint infection (PJI). However, it is unknown whether every microbial DNA signal detected by NGS is clinically relevant. This multi-institutional study was conceived to 1) identify species detected by NGS that may predict PJI, then 2) build a predictive model for PJI in a developmental cohort; and 3) validate the predictive utility of the model in a separate multi-institutional cohort. Methods. This multicenter investigation involving 15 academic institutions prospectively collected samples from 194 revision total knee arthroplasties (TKA) and 184 revision hip arthroplasties (THA) between 2017–2019. Patients undergoing reimplantation or spacer exchange procedures were excluded. Synovial fluid, deep tissue and swabs were obtained at the time of surgery and shipped to MicrogenDx (Lubbock, TX) for NGS analysis. Deep tissue specimens were also sent to the institutional labs for culture. All patients were classified per the 2018 Consensus definition of PJI. Microbial DNA analysis of community similarities (ANCOM) was used to identify 17 candidate bacterial species out of 294 (W-value >50) for differentiating infected vs. noninfected cases. Logistic Regression with LASSO model selection and random forest algorithms were then used to build a model for predicting PJI. For this analysis, ICM classification was the response variable (gold standard) and the species identified through ANCOM were the predictor variables. Recruited cases were randomly split in half, with one half designated as the training set, and the other half as the validation set. Using the training set, a model for PJI diagnosis was generated. The optimal resulting model was then tested for prediction ability with the validation set. The entire model-building procedure and validation was iterated 1000 times. From the model set, distributions of overall assignment rate, specificity, sensitivity, positive predictive value (PPV) and negative predicative value (NPV) were assessed. Results. The overall predictive accuracy achieved in the model was 75.9% (Figure 1). There was a high accuracy in true-negative and false-negative classification of patients using this predictive model (Figure 2), which has previously been a criticism of NGS interpretation and reporting. Specificity was 97.1%, PPV was 75.0%, and NPV was 76.2%. On comparison of the distribution of abundances between ICM-positive and ICM-negative patients, Staphylococcus aureus was the strongest contributor (F=0.99) to the predictive power of the model (Figure 3). In contrast, Cutibacterium acnes was less predictive (F=0.309) and noted to be abundant across both infected and noninfected revision TJA samples. Discussion. This study is the first to utilize predictive modeling algorithms on a large prospective multicenter database in order to transform analytic NGS data into a clinically relevant diagnostic signal. Our collaborative findings suggest the microbial DNA signal identified on NGS may be an independent useful adjunct for the diagnosis of PJI, as well as help identify causative organisms. Further work applying artificial intelligence tools will improve accuracy, predictive power and clinical utility of high-throughput sequencing technology. For figures, tables, or references, please contact authors directly

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Revision total knee arthroplasty (rTKA) accounts for approximately 5% to 10% of all TKAs. Although the complexity of these procedures is well recognized, few investigators have evaluated the cost and value-added with the implementation of a dedicated revision arthroplasty service. The aim of the present study is to compare and contrast surgeon productivity in several differing models of activity.

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The aim of this study was to determine if the Oxford Knee and Hip Score (OKHS) can accurately predict when a primary knee or hip referral is deemed nonsurgical versus surgical by the surgeon during their first consultation, and to identify nonsurgical OKHS screening thresholds.

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The aim of this study was to investigate the differences in 30-day outcomes between patients undergoing revision for an infected total hip arthroplasty (THA) compared with an aseptic revision THA.

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The purpose of this study was to compare outcomes of combined total joint arthroplasty (TJA) (total hip arthroplasty (THA) and total knee arthroplasty (TKA) performed during the same admission) versus bilateral THA, bilateral TKA, single THA, and single TKA. Combined TJAs performed on the same day were compared with those staged within the same admission episode.

Wear induces osteolysis leading to periprosthetic bone loss and TJA loosening. Inflammatory immune cells can form an aggressive interface membrane activating osteoclasts. The current study shows the effect of metal particles and ions triggering cellular responses. Blood samples from primary and revision TJA were analysed for systemic inflammation. PBMCs were cultured on different implant materials. Cellular response was monitored by qRT-PCR. Furthermore, cells were exposed to increasing concentrations of metal particles (10-7 and 10–8 particles/ml) and CoCl2 (50 µM and 100 µM). Cellular response was measured using WST-1 reduction, MitoSox-fluorescence and TUNEL-staining. Cobalt ion influx into osteoblasts was measured using FURA2-staining, cellular effects for HIF-1alpha and qRT-PCR. No inflammatory parameters were detected in patients' blood from primary and revision TJA. Short inflammatory reaction of their PBMCs was observed in in vitro culture on ceramic implants, whereas there was no such reaction to other tested implant martials. In MM6 and Jurkat cells only metal ions induced oxidative stress but did not significantly reduce cell viability. An increase in HIF1-alpha was observed in tissue containing large amounts of metal wear in comparison to plastic wear containing tissues and OA synovial tissue without wear particles. Cobalt ions were stored by osteoblasts via a calcium channel inducing hypoxia. This effect could be blocked using a TRPM blocking agent. Ceramic induces a short inflammatory response that may induce periprosthetic inflammation. Ionic Cobalt induces oxidative stress and hypoxia. Ionic metal exerts a more intense reaction on cells than particles

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

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The purpose of this article was to review the current literature pertaining to the use of mobile compression devices (MCDs) for venous thromboembolism (VTE) following total joint arthroplasty (TJA), and to discuss the results of data from our institution.

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

Total hip arthroplasty (THA) and Total knee arthroplasty (TKA) are successful operations that predictably restore function and provide pain relief for up to 20 years. What happens if they fail in the elderly patient? The purpose of this review was to evaluate pain relief, function and quality of life (QOL) in octogenarian patients undergoing revision total joint arthroplasty (TJA). We reviewed our surgical database to find all patients who were 80 years or older at the time of revision surgery. From 1993 through 2008, there were 61 revision THAs (52 patients) and 33 revision TKAs (29 patients). This represented 3% and 8% respectively of all arthroplasties and revision arthroplasties done during the same period. Outcomes evaluated include Harris Hip Scores (HHS), Knee Society Scores (KSS), complications, and QOL. The average follow-up for revision THA patients with completed Harris Hip Evaluations was 27 months (range: 3 – 126 months). HHS improved from 47 pre-operatively to 74 at most recent follow-up. Pain Scores improved from 20 to 39, Function Scores from 11 to 16, Activities Scores from 9 to 10, Deformity Scores from 2 to 4 and ROM Scores from 5 to 6. Complications occurred in 34% of these cases. The average follow-up for revision TKA patients with completed Knee Society Evaluations was 38 months (range: 11 – 98 months). KSS improved from 48 preoperatively to 84 at the most recent follow-up. Pain Scores improved from 22 to 43 and Function Scores from 20 to 34. Complications occurred in 47% of these cases. Total HHS and KSS greatly improved postoperatively with the most notable improvement in the Pain category. Complications were common, although most were considered minor. More severe complications occurred when revisions of all components were needed, more likely in TKA than THA. With careful selection, patient education and preoperative planning, revision TJA can be done safely and provide benefit for the elderly patient