Aim. Periprosthetic joint infection (PJI) is a devastating complication that develops after total joint arthroplasty (TJA) whose incidence is expected to increase over the years. Traditionally, surgical treatment of PJI has been based on algorithms, where early infections are preferably treated with debridement, antibiotics, and implant retention (DAIR), while late infections with two-stage revision surgery. Two-stage revision is considered the “gold standard” for treatment of chronic PJI. In this observational retrospective study, we investigated the potential role of inflammatory blood markers (neutrophil-to- lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), systemic inflammatory index (SII)], systemic inflammatory response index (SIRI), and aggregate index of systemic inflammation (AISI)) as prognostic factors in two-stage exchange arthroplasty for PJI. Method. A single-center retrospective analysis was conducted, collecting clinical data and laboratory parameters from patients submitted to prosthetic explantation for chronic PJI. Laboratory parameters (PCR, NLR, MLR, PLR, SIRI, SII and AISI) were evaluated at the explantation time, at 4, 6, 8 weeks after surgery and at reimplantation time. Correlation between laboratory parameters and surgery success was evaluated, defined as infection absence/resolution at the last follow up. Results. 57 patients with PJI were evaluated (62% males; average age 70 years, SD 12.14). Fifty-three patients with chronic PJI were included. Nineteen patients completed the two-stage revision process. Among them, none showed signs of re-infection or persistence of infection at the last available follow up. The other twenty-three patients did not replant due to persistent infection: among them, some (the most) underwent spacer retention; others were submitted to Girdlestone technique or chronic suppressive antibiotic therapy. Of the patients who concluded the two-stage revision, the ones with high SIRI values (mean 3.08 SD 1.7, p-value 0.04) and MLR values (mean 0.4 SD 0.2, p-value 0.02) at the explantation time were associated with a higher probability of infection resolution. Moreover, higher variation of SIRI and PCR, also defined respectively delta-SIRI (mean −2.3 SD 1.8, p-value 0.03) and delta-PCR (mean −46 SD 35.7, p-value 0.03), were associated with favorable outcomes. Conclusions. The results of our study suggest that, in patients with PJI undergoing two-stage, SIRI and MLR values and delta-SIRI and delta-PCR values could be predictive of favorable outcome. The evaluation of these laboratory indices, especially their determination at 4 weeks after removal, could therefore help to determine which patients could be successfully replanted and to identify the best time to replant

Total joint arthroplasty (TJA) is one of the commonest and most successful orthopaedic procedures used for the management of end-stage arthritis. With the recent introduction of robotic-assisted joint replacement, Computed tomography (CT) has become part of required pre-operative planning. The aim of this study is to quantify and characterise incidental CT findings, their clinical significance, and their effect on the planned joint arthroplasty. All consecutive patients undergoing an elective TJA (total joint arthroplasty; hip or knee) were retrospectively identified, over a 4-year period (December 2019 and November 2023). Data documented and analysed included patient demographics, type of joint arthroplasty, CT findings, their clinical significance, as well as potential delays to the planned arthroplasty because of these findings and subsequent further investigation. A total of 987 patients (female: 514 patients (52.1%)) undergoing TJA were identified (THA: 444 patients (45.0%); TKA: 400 patients (40.5%); UKA: 143 patients (14.5%)). Incidental findings within imaged areas were identified in 227 patients (23.0%). Of these findings, 74 (7.5%) were significant, requiring further investigation or management, 40 (4.1%) of which represented potential malignancy and 4 (0.4%) resulting in a new cancer diagnosis. A single patient was found to have an aneurysm requiring urgent vascular intervention. Surgery was delayed for further investigation in 4 patients (0.4%). Significant findings were more frequent in THA patients (THA: 43 (9.7%) TKA/UKA: 31 (5.7%). Within our cohort, 74 (7.5%) patients had significant incidental findings that required further investigations or management, with 4 (0.4%) having a previously undiagnosed malignancy. We strongly advocate that all robotic arthroplasty planning CTs are reviewed and reported by a specialist, to avoid missing undiagnosed malignancies and other significant diagnoses

Aim. Prosthetic joint infection (PJI) represents the second most frequent complication of total joint arthroplasty (TJA) with up to 20% of low-grade PJI treated as aseptic failure. Sensitive diagnostic criteria have been provided by EBJIS. However, to date there is no single test to reliably diagnose all PJIs. Studies of Mazzucco et al. and Fu et al. suggest that synovial fluid (SF) viscosity could be considered as an important marker for PJI. The primary aim of our study was to determine if SF viscosity is a more reliable diagnostic criterion of PJI than the SF cell count with differential (CCD), and the combined diagnostic value of SF viscosity and CCD. Method. We prospectively analysed the viscosity of SF samples obtained during TJA of hip and knee revisions. We sampled 2.5–5mL of SF for viscosity and CCD. Intraoperatively, 1mL of the sample was analysed for the CCD. The remaining SF was centrifuged for 4min at 7000rpm. The viscosity of the supernatant was determined on Ostwald viscometer as the time required to pass the viscometer at 20°C. During each surgery at least 5 microbiological and multiple histopathological samples were harvested, and explant sonication was performed. The diagnosis was based on EBJIS definition. The viscosity threshold for detecting PJI was set at 65 seconds. Results. Between December 2020 and January 2023, we analysed 65 knee and 47 hip TJA revision procedures. There were 55 septic and 57 aseptic diagnoses. As a diagnostic marker of PJI, SF viscosity achieved 100% sensitivity and 82.5% specificity, with area under the receiver operating characteristic curve (AUC) of 0.832 (95% CI 0.739, 0.925). The specificity and sensitivity of SF CCD were 98.2% and 78.2%, respectively, with AUC of 0.921 (95% CI 0.869, 0.974). Of the 10 cases incorrectly diagnosed as aseptic based on SF viscosity, 2 were acute traumas and 8 metalloses. The SF CCD in all these cases was <0.5. Of the 12 cases incorrectly diagnosed as aseptic based on SF CCD, 6 cases were culture negative, 4 C. acnes and 2 S. epidemidis isolates in microbiology. Taken together, SF viscosity and CCD achieved a combined AUC of 0.953 (95% CI 0.919, 0.987). Conclusions. Our study is the first to report that SF viscosity is more sensitive but slightly less specific for PJI than SF CCD. The study demonstrates diagnostic value of combining SF viscosity with CCD in decision making in TJA revision surgery

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

Total Joint Arthroplasty (TJA) is a successful orthopaedic procedure allowing dramatic clinical and functional improvements. Globally, there's been an increase in demand and performed cases associated with an increase in complications. Subsequently, focus on the prevention of complications has become important worldwide. The incidence of venous-thrombolic events (VTE) despite great attention has not diminished despite much investigation. A balance between efficacy and safety from the available agents is essential. Low molecular weight heparin (LMWH) has been commonly used, but oral anti-coagulants have become more popular. The aim of this study was to assess the adherence LMWH and the effectiveness and safety of preventing VTE in post-operative arthroplasty patients in a South African setting. We conducted a prospective cohort study that included hip and knee, primary and revision, arthroplasty patients who received thromboprophylaxis with one daily injection of LMWH for 14 days post discharge. Patients who omitted 1 or more doses during the follow up period were classified as “non adherent”. A questionnaire was used at follow up visits at least 6 weeks post-operatively. 100 consecutive patients were followed up. The mean age of patients was 63.45 years. There were 68 % female patients. There was a 92% compliance rate. 60 % of patients had the injection administered by a family member, 38 % administered it themselves and 2 % had the injection administered by health professionals. Venous thromboembolic events were confirmed in 5 % at 7.86 days after surgery. Three patients had persistent wound drainage after surgery, however, none required reoperation or readmission. Compliance with LMWH is high and is comparable with oral agents. It is effective in preventing VTE and safe with regards to bleeding and wound complications in a South African setting. Patient education regarding medications may improve compliance of the medication

Abstract. Introduction. Total joint arthroplasty (TJA) is one of the commonest and most successful orthopaedic procedures, used for the management of end-stage arthritis. With the recent introduction of robotic assisted joint replacement, Computed Tomography (CT) has become part of required pre-operative planning. The aim of this study is to quantify and characterise incidental CT findings, their clinical significance, and their effect on planned joint arthroplasty. Methodology. All consecutive patients undergoing an elective TJR (hip or knee arthroplasty) were retrospectively identified, over a 3-year period (December 2019 and December 2022). Data documented and analysed included patient demographics, type of joint arthroplasty, CT findings, their clinical significance, as well as potential delays to the planned arthroplasty because of these findings and subsequent further investigation. Results. A total of 624 patients (637 studies, 323 (51.8%) female, 301 (48.2%) male) were identified of which 163 (25.6%) showed incidental findings within the long bones or pelvis. Of these 52 (8.2%) were significant, potentially requiring further management, 32 (5.0%) represented potential malignancy and 4 (0.6%) resulted in a new cancer diagnosis. Conclusion. It is not currently national standard practice to report planning CT imaging as it is deemed an unnecessary expense and burden on radiology services. Within the study cohort 52 (8.2%) of patients had a significant incidental finding that required further investigation or management and 4 (0.6%) had a previously undiagnosed malignancy. In order to avoid the inevitability of a missed malignancy on a planning CT, we must advocate for formal reports in all cases

Abstract. Introduction. Minimum clinically important differences (MCIDs) are critical to understanding changes in patient-reported outcome measure (PROM) scores after total joint arthroplasty (TJA). The usage and adoption of MCIDs not been well-studied. This study was performed to IDENTIFY trends in PROM and MCID use after TJA over the past decade. Methods. All articles published in the calendar years of 2010 and 2020 in CORR, JBJS, and the Journal of Arthroplasty were reviewed. Articles relating to clinical outcomes in primary total hip arthroplasty (THA) or total knee arthroplasty (TKA) were included. For each article, all reported PROMs and (if present) accompanying MCIDs were recorded. The use of PROMs and MCIDs were compared between articles published in 2010 and 2020. Results. Overall, 263 articles from 2010 and 546 articles from 2020 were included. The total number of articles reporting any PROM after THA and TKA increased from 131 in 2010 to 194 in 2020, but the proportion of articles reporting PROMs decreased from 49.8% (131/263) to 35.5% (194/546). Both the total number and proportion of articles reporting MCIDs increased from 2.3% (3/131) in 2010 to 16.5% (32/194) in 2020. These trends persisted when analyzing THA and TKA articles individually. Conclusions. Both the absolute number and proportion of articles reporting MCIDs in conjunction with PROMs after TJA has increased in the past decade but remains low. We recommend that journal editors and meeting organizers encourage the inclusion of MCID information in all reports on clinical outcomes after joint replacement

Both total joint arthroplasty (TJA) and Alzheimer's Disease (AD) are prevalent in elderly populations. It is the goal of this study to determine if the presence of implant metals originating from TJA correlates with the onset with higher implant metal content in the brain and AD pathology. Tissue samples from four brain regions of 701 (229 with TJA) participants from an ongoing longitudinal cohort study (Rush Memory and Aging Project) was analyzed including the inferior-temporal-cortex (ITC), which is associated with early onset of AD. Implant metal (Co, Cr, Mo, Ti, Al) content was determined by ICP-MS. Comparisons were conducted between the no-TJA-group and a TJA group. Due to the higher likelihood of Co release the TJA group was further differentiated in a THA (N=146) and a TKA/TSA (N=83) group. Diffuse and neuritic amyloid plaques and phosphorylated tau were assessed and summarized as standard measures of AD pathology. We used separate linear regression models adjusted for age, sex, education, and APOɛ4-status for the associations of all metals (log-transformed) with global AD pathology, amyloid plaques, and phosphorylated tau. The THA group had higher cobalt content across all brain regions (p=0.003) and within the ITC (p=0.051) compared to the no-TJA group, whereas the TKA/TSA group did not. Across all tissue samples, Co was associated with higher amyloid load (β=0.35, p=0.027), phosphorylated tau (β=0.47, p=0.011), and global AD pathology (β=0.19, 0.0004) in the ITC. The presence of TJA itself was not associated with AD pathology. We showed that only Co content was higher within the ITC in persons with THA. We found among all tested metals that Co was consistently associated with AD pathology. Although we found an association of cobalt with AD pathology, the cross-sectional nature of this study does not allow the determination of cause and effect

Excessive opioid prescriptions after total joint arthroplasty (TJA) increase risks for adverse opioid related events, chronic opioid use, and increase the availability of opioids for unlawful diversion. Thus, decreasing postoperative prescriptions may improve quality after TJA. Concerns exist that a decrease in opioids prescribed may increase complications such as readmissions, emergency department (ED) visits or worsened patient reported outcomes (PROs). The purpose of this quality improvement study was to explore whether a reduction in opioids prescribed after TJA resulted in increased complications. Methods: Data originated from a statewide arthroplasty database (MARCQI). The database collects over 96% of all TJA performed in the state of Michigan, USA. Data was prospectively abstracted and included OMEs prescribed at discharge, readmissions, ED visits within 30 days and PROs. Data was collected one year before and after the creation of an opioid prescribing protocol that had decreased prescriptions by approximately 50% in opioid naive and tolerant patients. Trends were monitored using Shewhart control charts. 84,998 TJA over two-years were included. All groups showed a reduction in opioids prescribed. Importantly, no increased complications occurred concomitant to this reduction. No increases in ED visits or readmissions, and no decreases in KOOSJR/HOOSJR/PROMIS10 scores were noted in any of the groups. Using large data sets and registries can drive performance and improve quality. The MARCQI Postoperative opioid prescription recommendations and performance measures decreased total oral morphine equivalents prescribed over a large and diverse population by approximately 50% without decreasing PROs or increasing ED visits or hospital readmissions. A reduction in opioids prescribed after TJA can be accomplished safely and without an increase in complications across a large population

Prosthetic joint infection (PJI) remains one of the most challenging complications to manage following total joint arthroplasty (TJA). There is a paucity of published data on the management of PJI in smaller, rural hospital settings. In this study, we investigate [1] the success rate of surgical management for PJI following TJA and [2] the microbiology of infecting organisms in this unique geographical environment. We performed a retrospective single-centre study at a rural hospital (Southland Hospital, Invercargill, New Zealand) over a 3-year period (2019 to 2022). All patients presenting with a first episode of PJI fulfilling Musculoskeletal Infection Society criteria after hip or knee arthroplasty were included. All patients had a minimum follow up of 6 months. Treatment success was defined eradication of infection. Twenty-one cases (14 hips and 7 knees) were identified. These were managed with Debridement, antibiotics, and implant retention (DAIR) procedure (n=14, 67%), single-stage revision (n=6, 29%), or long-term suppressive antibiotics (n=1, 4%). Of the DAIR patients, infection recurred in 50% and underwent subsequent revision. Of the single-stage revision patients, 17% failed and underwent subsequent revision. The overall success rate was 90%. Methicillin-sensitive Staphylococcus aureus (MSSA) was the most isolated pathogen (57%,) with no methicillin-resistance Staphylococcus aureus (MRSA) identified. Overall, 90% of infecting organisms were cefazolin sensitive. These results suggest that management of PJI is a safe and viable treatment option when performed in a rural hospital setting, with comparable treatment success rates to urban centres. The incidence of MRSA is low in this setting. Rates of antibiotic resistance were relatively low and most organisms were sensitive to cefazolin, the routine antibiotic used in prophylaxis

The February 2023 Hip & Pelvis Roundup³⁶⁰ looks at: Total hip arthroplasty or internal fixation for hip fracture?; Significant deterioration in quality of life and increased frailty in patients waiting more than six months for total hip or knee arthroplasty: a cross-sectional multicentre study; Long-term cognitive trajectory after total joint arthroplasty; Costal cartilage grafting for a large osteochondral lesion of the femoral head; Foley catheters not a problem in the short term; Revision hips still a mortality burden?; How to position implants with a robotic arm; Uncemented stems in hip fracture?

Same day home (SDH) discharge in total joint arthroplasty (TJA) has increased in popularity in recent years. The objective of this study was to evaluate the causes and predictors of failed discharges in planned SDH patients. A consecutive cohort of patients who underwent total knee (TKA) or total hip arthroplasty (THA) that were scheduled for SDH discharge between April 1, 2019 to March 31, 2021 were retrospectively reviewed. Patient demographics, causes of failed discharge, perioperative variables, 30-day readmissions and 6-month reoperation rates were collected. Multivariate regression analysis was undertaken to identify independent predictors of failed discharge. The cohort consisted of 527 consecutive patients. One hundred and one (19%) patients failed SDH discharge. The leading causes were postoperative hypotension (20%) and patients who were ineligible for the SDH pathway (19%). Two individual surgeons, later operative start time (OR 1.3, 95% CI, 1.15-1.55, p=0.001), ASA class IV (OR 3.4, 95% CI, 1.4-8.2; p=0.006) and undergoing a THA (OR 2.0, 95% CI, 1.2-3.1, p=0.004) were independent predictors of failed SDH discharge. No differences in age, BMI, gender, surgical approach or type of anesthetic were found (p>0.05). The 30-day readmission or 6-month reoperation were similar between groups (p>0.05). Hypotension and inappropriate patient selection were the leading causes of failed SDH discharge. Significant variability existed between individual surgeons failed discharge rates. Patients undergoing a THA, classified as ASA IV or had a later operative start time were all more likely to fail SDH discharge

Canada is second only to the United States worldwide in the number of opioid prescriptions per capita. Despite this, little is known about prescription patterns for patients undergoing total joint arthroplasty (TJA). The purpose of this study was to detail preoperative opioid use patterns and investigate the effect it has on perioperative quality outcomes in patients undergoing elective total hip and total knee arthroplasty surgery (THA and TKA). The study cohort was constructed from hospital Discharge Abstract Data (DAD) and National Ambulatory Care Reporting System (NACRS) data, using Canadian Classification of Health Intervention codes to select all primary THA and TKA procedures from 2017-2020 in Nova Scotia. Opioid use was defined as any prescription filled at discharge as identified in the Nova Scotia Drug Information System (DIS). Emergency Department (ED) and Family Doctor (FD) visits for pain were ascertained from Physician Claims data. Multivariate logistic regression was used to test for associations controlling for confounders. Chi-squared statistics at 95% confidence level used to test for statistical significance. In total, 14,819 TJA patients were analysed and 4306 patients (29.0%) had at least one opioid prescription in the year prior to surgery. Overall, there was no significant difference noted in preoperative opiate use between patients undergoing TKA vs THA (28.8% vs 29.4%). During the period 2017-2019 we observed a declining year-on-year trend in preoperative opiate use. Interestingly, this trend failed to continue into 2020, where preoperative opiate use was observed to increase by 15% and exceeded 2017 levels. Within the first 90 days of discharge, 22.9% of TKA and 20.9% of THA patients presented to the ED or their FD with pain related issues. Preoperative opiate use was found to be a statistically significant predictor for these presentations (TKA: odds ratio [OR], 1.45; 95% confidence interval [CI], 1.29 to 1.62; THA: OR, 1.46; 95% CI, 1.28 to 1.65). Preoperative opioid consumption in TJA remains high, and is independently associated with a higher risk of 90 day return to the FD or ED. The widespread dissemination of opioid reduction strategies introduced during the middle of the last decade may have reduced preoperative opiate utilisation. Access barriers and practice changes due to the COVID-19 pandemic may now have annulled this effect

Aim. Periprosthetic joint infections (PJI) are severe complications after total joint arthroplasty (TJA). Up to now, a gold standard in the diagnostics of PJI is missing. Small extracellular vesicles (sEVs) are secreted by all types of cells and play a key role in immune response in presence of infection (1). In this prospective study, the diagnostic accuracy of sEVs in the synovial fluid to detect PJI of knee, hip and shoulder joints was investigated. We hypothesized increased surface markers of sEVs in PJI compared to aseptic complications (e.g. implant loosening, stress shielding related pain). Method. Synovial fluid from 48 patients with painful arthroplasty was examined. The distinction between aseptic and infectious cases was made on the basis of the 2018 Definition of Periprosthetic Hip and Knee Infection (2). 35 (72,9%) probands assigned to aseptic and 13 patients (27,1%) to PJI group. Immuno-fluorescence flow cytometry served to document the concentrations of CD9, CD63, CD66b, CD82 and HLA-DR on sEVs. Results. The concentration of CD9 surface marker on sEVs in synovial fluid was significantly lower (p=0.002) in PJI group than in aseptic group. In contrast, the levels of CD82 on sEVs in synovial fluid was significantly higher (p<0.0001) in the PJI group than in aseptic group. The concentrations of CD63, CD66b and HLA-DR on sEVs in synovial fluid did not differ significantly between the two cohorts (CD63: p=0.372; CD66b: p=0.634; HLA-DR: p=0.558). Conclusions. Overall, the significance of sEVs in the diagnostics of PJI is not well enough understood and the subject of current research and scientific discussion. Our data suggest, that CD82 and CD9 on sEVs in synovial fluid are promising biomarkers to differentiate between PJI and aseptic complications

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. Prosthetic joint infection (PJI) presents the second most common complication of total joint arthroplasty (TJA). Accumulating evidence suggests that up to 20% of aseptic failures are low-grade PJI. However, there is still no single test to reliably diagnose all PJI. In his thesis, Mazzucco emphasized the viscosity differences between normal, osteoarthritic, and rheumatic synovial fluid. Similarly, a recent study by Fu et al. reported significantly lower viscosity in patients with PJI compared to the aseptic failure cohort. The primary aim of our study was to determine whether synovial fluid viscosity is a more reliable diagnostic criterion for PJI compared to the synovial fluid cell count with differential and serum C-reactive protein (CRP) levels. Method. We prospectively analyzed the viscosity of synovial fluid samples obtained during TJA of hip and knee joint revision procedures. We sampled 2.5–5 mL of synovial fluid for viscosity measurement. The samples were centrifuged (4 min at 7000 rpm) and the resulting supernatant was immediately transferred into the Ostwald viscometer. Viscosity was derived from the time required for a given volume of synovial fluid to pass the viscometer at 20 °C. The synovial fluid samples were also analysed for their cell count with differential and serum CRP was measured. The definite diagnosis of PJI was established on basis of EBJIS criteria. For the viscosity, the threshold for detecting PJI was set at 65 seconds. Results. Between December 2020 and March 2021, we analyzed 12 knee and 11 hip TJA revision samples. These included 14 septic and 9 aseptic synovial fluid samples. The average viscometer time in the PJI group was 31s (range 20–48s) compared to 247s (range 68–616s) in the group of aseptic revision procedures. The specificity and sensitivity of our viscosity measurements were 100%. The sensitivity and specificity of cell count was 100% and 85.7%, for the synovial fluid differential they were 100% and 85.7%, and for the CRP they were 88.9% and 71.4%, respectively. Conclusions. Our study is the first to report a significant difference in synovial fluid viscosity between the PJI and the aseptic cohort. It points towards the diagnostic superiority of viscosity measurements over conventional synovial fluid cell count, synovial fluid differential, and serum CRP levels. Albeit currently limited by small sample size, the study remains ongoing

Aim. Whether laminar airflow (LAF) in the operating room (OR) is effective for decreasing periprosthetic joint infection (PJI) following total joint arthroplasty (TJA) remains a clinically significant yet controversial issue. This study investigated the association between operating room ventilation systems and the risk of PJI in TJA patients. Method. We performed a retrospective observational study on consecutive patients undergoing primary total knee arthroplasty (TKA) and total hip arthroplasty (THA) from January 2013-September 2017 in two surgical facilities within a single institution, with a minimum 1-year follow-up. All procedures were performed by five board-certified arthroplasty surgeons. The operating rooms at the facilities were equipped with LAF and turbulent ventilation systems, respectively. Patient characteristics were extracted from clinical records. PJI was defined according to Musculoskeletal Infection Society criteria within 1-year of the index arthroplasty. A multivariate logistic regression model was performed to explore the association between LAF and risk of 1-year PJI, and then a sensitivity analysis using propensity score matching (PSM) was performed to further validate the findings. Results. A total of 6,972 patients (2,797 TKA, 4,175 THA) were included. The incidence of PJI within 1 year for patients from the facility without laminar flow was similar at 0·4% to that of patients from the facility with laminar flow at 0·5%. In the multivariate logistic regression analysis, after all confounding factors were taken into account, the use of LAF was not significantly associated with reduction of the risk of PJI. After propensity score matching, there was no significant difference in the incidence of PJI within 1 year for patients between the two sites. Conclusions. The use of LAF in the operating room was not associated with a reduced incidence of PJI following primary TJA. With an appropriate perioperative protocol for infection prevention, LAF does not seem to play a protective role in PJI prevention

Introduction and Objective. An important subset of patients is dissatisfied after total joint arthroplasty (TJA) due to residual functional impairment. This study investigated the assessment of objectively measured step-up performance following TJA, to identify patients with poor functional improvement after surgery, and to predict residual functional impairment during early postoperative rehabilitation. Secondary, longitudinal changes of block step-up (BS) transfers were compared with functional changes of subjective patient reported outcome measures (PROMs) following TJA. Materials and Methods. Patients with end stage hip or knee osteoarthritis (n = 76, m/f = 44/32; mean age = 64.4 standard deviation 9.4 years) were measured preoperatively and 3 and 12 months postoperatively. PROMs were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) function subscore. BS transfers were assessed by wearable-derived measures of time. In our cohort, subgroups were formed based on either 1) WOMAC function score or 2) BS performance, isolating the worst performing quartile (impaired) of each measure from the better performing others (non-impaired). Subgroup comparisons were performed with the Man-Whitney-U test and Wilcoxon Signed rank test resp. Responsiveness was calculated by the effect size, correlations with Pearson's correlation coefficient. A regression analysis was conducted to investigate predictors of poor functional outcome. Results. WOMAC function scores were strongly correlated to WOMAC pain scores (Pearson's r=0.67–0.84) and moderately correlated to BS performance (Pearson's r = 0.31–0.54). Prior to surgery, no significant differences for WOMAC function scores and BS performance were found between the impaired and non-impaired subgroups. One year after TJA, our cohort performed significantly better at WOMAC and BS with largest effect size for the non-impaired subgroups (0.62 and 0.43 resp.) At 12 months postop, 56% of patients allocated to the impaired subgroup defined by WOMAC, represented the impaired subgroup defined by BS. Allocation to the impaired subgroup at 3 months postop, raised the odds for belonging to the impaired subgroup at 12 months for WOMAC with an odds ratio=19.14 (67%) and for BS with an odds ratio=4.41 (42%). Conclusions. Assessment of BS performance following TJA reveals residual functional impairment that is not captured by pain-dominated PROMs. Its additional use may help to early identify those patients at risk for a poor outcome

Introduction. Pulmonary embolism (PE) complicates up to 1% of total joint arthroplasties (TJA). Many PE treatment guidelines call for immediate initiation of therapeutic anticoagulation. Options include Xa inhibitors, Enoxaparin, and Warfarin. Deciding between these is a balance of the efficacy and the risks. Little data exists regarding the risks of each of these treatment options for treating PE in arthroplasty patients. Methods. We examined the records of 29,270 patients who underwent a primary total joint arthroplasty (TJA), defined as a unilateral total knee arthroplasty (TKA) (18,987) or total hip arthroplasty (THA) (10,283), between 2/2016 and 12/2018 at our institution and identified 338 (242 TKA, 96 THA) patients who developed an in-hospital PE treated with therapeutic anticoagulation. The patients were treated with therapeutic doses of Xa inhibitors, enoxaparin or warfarin. The type and frequency of complications were determined and classified as major or minor. Major complication included: bleeding requiring surgery, GI bleed requiring treatment, >2 unit transfusion and mortality. Minor complications included wound drainage, bleeding not requiring surgery, and thrombocytopenia. Results. Overall complication rates were high for all treatments. Xa inhibitors had the lowest complication rate at 14% compared to 20% for enoxaparin and 20.7% for warfarin though the difference did not quite reach statistical significance (p=.054). Both major and minor complication were lower with Xa inhibitors, but again the difference was not statistically significant (p=0.67). There was no significant difference in complications between TKA groups (p=0.73) or THA groups (p=0.83). Gender and body mass index were not predictive of major or minor complications. Discussion. Our results demonstrate high complication rates associated with modern therapeutic anticoagulation protocols for perioperative PE following TJA. Patients who receive therapeutic anticoagulation postoperatively are at high risk for complication. Xa inhibitors may decrease these risks, but larger studies are required

Introduction. Patients with aseptic loosening, a cause of failure in uncemented total joint arthroplasty (TJA), often present with fibrous tissue at the bone-implant interface. 1. In this study, we characterize the presence of neutrophil extracellular traps (NETs) in the intramedullary fibrotic membrane of aseptic loosening patients. We further explore the role of NETs, mediated by peptidyl arginine deiminase (PAD4), in peri-implant fibrosis and osseointegration failure through a murine model of unstable tibial implantation. 2–4. Methods. Peri-implant membrane was retrieved from five patients during total hip revision surgery and analyzed for the presence of NETs (citH3+ with extracellular DNA) via immunofluorescence. A Ti-6Al-4V implant was inserted in an oversized drill-hole in the right proximal tibia of 8-week-old C57BL/6J and PAD4 knockout mice (n=3 per group). Fourteen days later, all mice were euthanized, and implanted tibias were dissected. Fibrosis and osseointegration at the bone-implant interface were assessed by micro-computed tomography (microCT) and hematoxylin and eosin (H&E) staining. H&E samples were scored blindly by the investigator and another observer for signs of poor (score=0) to excellent osseointegration (score=3) using a rubric established in our lab. Results. NETs were found in peri-implant membrane collected from aseptic loosening patients (Figure 1a) and at the bone-implant interface in a murine model (Figure 1b). Unstable implants in wild type mice failed to osseointegrate, indicated by presence of fibroblast-like cells (dashed arrow), immature bone matrix (Figure 1c), low bone volume fraction (BV/TV) and bone surface area (BS) (Figure 1e). Unstable implants in PAD4. −/−. mice showed signs of good osseointegration such as mature trabeculae (solid arrow) (Figure 1d), higher BV/TV (p<0.10) and BS (p<0.05) (Figure 1f). Histological osseointegration scoring indicated wildtype mice exhibited an average score of 0.83 and PAD4. −/−. exhibited an average score of 2.5 (p<0.05, weighted Cohen's kappa = 0.714) (Figure 1g). Conclusion. NETs were characterized in fibrotic tissue in both aseptic loosening patients and in a murine model of unstable tibial implantation. NET inhibition was able to successfully prevent peri-implant fibrosis and osseointegration failure, leading the way for a potential novel non-invasive therapeutic approach for the treatment of aseptic loosening. For any figures, tables, or references, please contact the authors directly