The Gut Microbiome and Joint Microbiome Show Alterations in Patients with Knee Osteoarthritis Versus Controls: A Systematic Review.

PURPOSE: To assess the current scientific literature on the microbiome's relationship with knee osteoarthritis (OA), with specific focuses on the gut microbiome-joint axis and joint microbiome-joint axis. METHODS: A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, searching PubMed, Embase, and Cochrane databases for relevant English-language clinical studies on the gut and/or joint microbiomes' association with knee OA in humans. Bias was evaluated using the methodological index for non-randomized studies score. RESULTS: Thirty-five thousand bacterial species comprise the gut microbiome; approximately 90% are members of the phyla Bacteroides and Firmicutes. Symbiosis between the gut microbiome and host under normal physiological conditions positively affects host growth, development, immunity, and longevity. Gut microbiome imbalance can negatively influence various physiological processes, including immune response, inflammation, metabolism, and joint health including development of knee OA. In addition, next generation gene sequencing suggests the presence of microorganisms in the synovial fluid of osteoarthritic knees, and distinct microbiome profiles detected are presumed to play a role in the development of OA. With regard to the gut microbiome, consistent alterations in microbial composition between OA patients and controls are noted, in addition to several associations between certain gut bacteria with OA-related knee pain, patient-reported outcome measure performance, imaging findings, and changes in metabolic and inflammatory pathways. Regarding the joint microbiome, studies revealed increased levels of lipopolysaccharide (LPS) and LPS-binding protein in synovial fluid are associated with activated macrophages, and correlated with worsened osteophyte severity, joint space narrowing, and pain scores in knee OA patients. In addition, studies demonstrated various microbial composition differences in OA patients compared to control, with certain joint microbes directly associated with OA pathogenesis, inflammation, and metabolic dysregulation. CONCLUSIONS: The gut microbiome-joint axis and joint microbiome shows alterations in microbial composition between osteoarthritic patients and controls. These alterations are associated with perturbations of metabolic and inflammatory pathways, imaging findings, osteoarthritis-related pain, and patient reported outcome measure performance. LEVEL OF EVIDENCE: Systematic Review; Level III.

Gloves Contamination During Revision Surgery for Periprosthetic Joint Infection.

BACKGROUND: The use of double gloving has become a standard practice for joint replacement surgeons. However, since there are limited data on how gloves are contaminated during both primary and revision arthroplasty, no precise protocol exists to direct surgeons on when, or if, to change their gloves. The goals of this preliminary study were to evaluate the contamination of gloves during total joint arthroplasties (TJAs). METHODS: We included 25 infected cases and 10 primaries, which were performed at the same institution using the same surgical protocol from 3 fellowship trained surgeons. Samples were taken every 20 minutes from the start of the surgery until the joint was irrigated. Procedural steps were noted. To evaluate cross-contamination during infected cases, we sampled gloves using blood agar plates. In primary cases, culture swabs of anterior chamfer cuts and sterile instruments on the back table were used as negative controls. Next-generation sequencing (NGS) was used as an adjunct to identify low virulence bacteria. RESULTS: In the primary cases, all samples were found culture negative but 3 (8.1%) of the 37 samples were found to have a low, unidentifiable bacterial mass via NGS testing. In the infected cases, 41 (59.4%) of the 69 samples yielded positive microbial results. The positivity rate was higher in the samples collected after the arthrotomy was performed (70%) compared to samples collected before the arthrotomy was performed (40%), and the surgeon was only dissecting superficial layers (P = .502). CONCLUSION: Gloves seem to be a common source of cross-contamination in the intraoperative field during revision TJA. Due to the higher percent of positive samples following the opening of the joint, we hypothesize that the arthrotomy allows for the spread of bacteria across the operative site. While further investigation is necessary to formulate a precise protocol for the changing of gloves during TJA, it may be beneficial to perform a thorough irrigation of the joint and change of the gloves immediately following arthrotomy.

The 2023 Orthopaedic Research Society's International Consensus Meeting on musculoskeletal infection: Summary from the host immunity section.

Musculoskeletal infections (MSKI), which are a major problem in orthopedics, occur when the pathogen eludes or overwhelms the host immune system. While effective vaccines and immunotherapies to prevent and treat MSKI should be possible, fundamental knowledge gaps in our understanding of protective, nonprotective, and pathogenic host immunity are prohibitive. We also lack critical knowledge of how host immunity is affected by the microbiome, implants, prior infection, nutrition, antibiotics, and concomitant therapies, autoimmunity, and other comorbidities. To define our current knowledge of these critical topics, a Host Immunity Section of the 2023 Orthopaedic Research Society MSKI International Consensus Meeting (ICM) proposed 78 questions. Systematic reviews were performed on 15 of these questions, upon which recommendations with level of evidence were voted on by the 72 ICM delegates, and another 12 questions were voted on with a recommendation of "Unknown" without systematic reviews. Two questions were transferred to another ICM Section, and the other 45 were tabled for future consideration due to limitations of available human resources. Here we report the results of the voting with internet access to the questions, recommendations, and rationale from the systematic reviews. Eighteen questions received a consensus vote of ≥90%, while nine recommendations failed to achieve this threshold. Commentary on why consensus was not achieved on these questions and potential ways forward are provided to stimulate specific funding mechanisms and research on these critical MSKI host defense questions.

Intraoperative Greater Trochanteric Fractures During Revision Total Hip Arthroplasty May Not Always Need Surgical Fixation.

Many fixation techniques have been described to manage intraoperative greater trochanteric (GT) fractures during revision total hip arthroplasty (rTHA), but complications such as broken hardware and bursitis are common. The purpose of this study was to determine whether surgical fixation of an intraoperative GT fracture resulted in improved outcomes in rTHA. We reviewed a consecutive series of 1442 rTHA patients at our institution from 2008 to 2019. We identified all patients with an intraoperative GT fracture and noted whether the fracture was fixed surgically or left without fixation. Demographics, comorbidities, complications, radiographic union, and dislocations were compared between the groups. Of the 44 (3%) intra-operative GT fractures identified, 23 (52%) underwent fixation, most commonly with claw plates (8 patients) and cables (10 patients). There were no differences in the rates of radiographic union (86% vs 100%, P=.100), dislocations (4% vs 10%, P=.599), or re-revision (10% vs 13%, P=1.000) between the groups. Patients undergoing fixation had a higher rate of bursitis postoperatively, but it was not significant with the numbers available (35% vs 10%, P=.072). Our cohort of GT fractures at a large revision referral institution represents the largest reported series of GT fractures during rTHA. Surgical fixation in rTHA did not show improved outcomes in terms of dislocation, re-revision, and radiographic union compared with those fractures that were not fixed. There was a trend toward increased postoperative bursitis in the group undergoing surgical fixation. Further research is needed on this topic, as the number of rTHAs continues to increase. [Orthopedics. 2023;46(5):297-302.].

Plasma D-Dimer Is Noninferior to Serum C-Reactive Protein in the Diagnosis of Periprosthetic Joint Infection.

BACKGROUND: No single test has demonstrated absolute accuracy in the diagnosis of periprosthetic joint infection (PJI). Serological markers are often used as screening tools in the workup of patients with suspected PJI. This study aimed to determine the diagnostic utility of plasma D-dimer for PJI in a variety of clinical scenarios. METHODS: This prospective study enrolled 502 patients undergoing revision hip or knee arthroplasty. PJI was defined per a modified version of the 2018 International Consensus Meeting (ICM) criteria. Plasma D-dimer, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and fibrinogen were measured preoperatively. Receiver operating characteristic curves were used to assess the utility of each biomarker in the diagnosis of PJI. Pairwise comparison with Bonferroni correction was performed to determine whether the differences in areas under the curve (AUCs) between the markers were significant. RESULTS: Of the 412 patients included, 317 (76.9%) did not have an infection (aseptic group) and 95 (23.1%) had an infection (PJI group). All 4 serological markers, D-dimer (AUC, 0.860; sensitivity, 81.3%; specificity, 81.7%), CRP (AUC, 0.862; sensitivity, 90.4%; specificity, 70.0%), ESR (AUC, 0.833; sensitivity, 73.9%; specificity, 85.2%), and fibrinogen (AUC, 0.798; sensitivity, 74.7%; specificity, 75.4%), demonstrated comparable accuracy for the diagnosis of PJI (all p > 0.05). When examining the performance of the different inflammatory markers in diagnosing infection caused by indolent organisms, D-dimer demonstrated the highest sensitivity at 93.8%. CONCLUSIONS: We found that plasma D-dimer was noninferior to serum CRP and ESR in the diagnosis of PJI and may be a useful adjunct when screening patients undergoing revision total joint arthroplasty. LEVEL OF EVIDENCE: Diagnostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Gut permeability may be associated with periprosthetic joint infection after total hip and knee arthroplasty.

A growing number of recent investigations on the human genome, gut microbiome, and proteomics suggests that the loss of mucosal barrier function, particularly in the gastrointestinal tract, may substantially affect antigen trafficking, ultimately influencing the close bidirectional interaction between the gut microbiome and the immune system. This cross-talk is highly influential in shaping the host immune system function and ultimately affecting the outcome of interventions. We hypothesized that the loss of mucosal barrier in the gut may be associatedto acute and chronic periprosthetic joint infections (PJI). Zonulin, soluble CD14 (sCD14), and lipopolysaccharide (LPS) were tested in plasma as part of a prospective cohort study of patients undergoing primary arthroplasty or revision arthroplasty because of an aseptic failure or PJI (as defined by the 2018 criteria). All blood samples were collected before antibiotic administration. Samples were tested using commercially available enzyme-linked immunosorbent assays as markers for gut permeability. A total of 134 patients were included in the study of which 44 patients had PJI (30 chronic and 14 acute), and the remaining 90 patients were categorized as non-infected that included 64 patients revised for aseptic failure, and 26 patients undergoing primary total joint arthroplasty. Both Zonulin (7.642 ± 6.077 ng/mL vs 4.560 ± 3.833 ng/mL; p < 0.001) and sCD14 levels (555.721 ± 216.659 ng/mL vs 396.872 ± 247.920 ng/mL; p = 0.003) were significantly elevated in the PJI group compared to non-infected cases. Higher levels of Zonulin were found in acute infections compared to chronic PJI (11.595 ± 6.722 ng/mL vs. 5.798 ± 4.841 ng/mL; p = 0.005). This prospective study reveals a possible link between gut permeability and the 'gut-immune-joint axis' in PJI. If this association continues to be borne out with a larger cohort and more in-depth analysis, it will have a clinically significant implication in managing patients with PJI. It may be that in addition to the administration of antimicrobials, patients with PJI and other orthopaedic infections may benefit from administration of gastrointestinal modulators such as pro and prebiotics.

Osteoarthritis Can Also Start in the Gut: The Gut-Joint Axis.

Background: Osteoarthritis is a common cause of pain and disability with an increasing prevalence among the global population (Hunter and Bierma-Zeinstra in Lancet 393(10182):1745-1759, 2019; Zhang and Jordan in Clinics in Geriatric Medicine 26(3):355-369, 2010). Altered immune responses and low-grade systemic inflammation driven by gut dysbiosis are being increasingly recognized as contributing factors to the pathophysiology of OA (Tan et al. in International Journal of Rheumatic Diseases. https://doi.org/10.1111/1756-185X.14123, 2021; Binvignat et al. in Joint, Bone, Spine 88(5):105203, 2021; Ramasamy et al. in Nutrients 13(4):1272, 2021), which increased the interest in the so-called "gut-joint axis". The various microbiota in the gastrointestinal tract is commonly referred to as the gut microbiome. The gut microbiome is affected by age, sex, and immune system activity as well as medications, environment, and diet (Arumugam in Nature. https://doi.org/10.1038/nature09944, 2011). The microbiome is pivotal to maintain host health and contributes to nutrition, host defense, and immune development (Nishida et al. in Clinical Journal of Gastroenterology 11:1-10, 2018). Alterations in this microbiome can induce dysbiosis, which is associated with many human disease states including allergies, autoimmune disease, diabetes, and cancer (Lin and Zhang in BMC Immunology 18(1):2, 2017). A gut-joint axis is proposed as a link involving the gastrointestinal microbiome, the immune response that it induces, and joint health. Results: Emerging evidence has shown that there are specific changes in the microbiome that are associated with osteoarthritis, including increased Firmicutes/Bacteroides ratio, Streptococcus spp. prevalence, and local inflammation (Collins in Osteoarthritis and Cartilage. https://doi.org/10.1016/j.joca.2015.03.014, 2015; Rios in Science and Reports. https://doi.org/10.1038/s41598-019-40601-x, 2019; Schott in JCI insight. https://doi.org/10.1172/jci.insight.95997, 2018; Boer et al. in Nature Communications 10:4881, 2019). Both the innate and adaptive immune systems are affected by the gut microbiome and can become dysregulated in dysbiosis which ultimately triggers events associated with joint OA. Conclusions: The gut is an intriguing and novel target for OA therapy. Dietary modification or supplementation with fiber, probiotics, or prebiotics could provide a positive impact on the gut joint axis.

Many Common Pathogens are Present in the Operative Room Air During Surgery.

BACKGROUND: The main objective of this study was to assess the sanitary measures of operating theaters using next-generation sequencing. METHODS: Air was sampled from the operating room for the whole duration of 10 surgical days of "clean" (no infection cases) procedures (6 hip/knee arthroplasty and 4 spine cases). Controls consisted of samples at the beginning of the day (1 hour before the surgery started) and at the end of the day after terminal cleaning. One additional control sample, consisting of a culture swab that was opened and exposed to the air for 5 seconds, was collected at each time point. All samples were sent for next-generation sequencing analysis (16S rRNA sequencing) for bacterial identification. RESULTS: Overall, 306 samples were collected (159 controls and 147 experimental). Microbial DNA was detected in only 1 control sample, while 18 (12.2%) experimental samples were positive for microbial DNA. The most common organisms retrieved were Escherichia coli (6/18, 30%), Cutibacterium acnes (3/18, 15%), and Pseudomonas aeruginosa (2/18, 11.1%). There was no difference in positive samples between arthroplasty and spine cases (P > .05). CONCLUSION: Microbial organisms are not uncommonly present in the operating room air during hip and knee arthroplasties and spine procedures.

Periprosthetic Joint Infection and the Trojan Horse Theory: Examining the Role of Gut Dysbiosis and Epithelial Integrity.

BACKGROUND: Periprosthetic joint infection (PJI) is an uncommon yet dreadful complication after total joint arthroplasty. Emerging evidence suggested a role for the gut microbiome in the pathogenesis of such infections as a reservoir of opportunistic pathogens. METHODS: A secondary analysis of an ongoing trial looking at gut dysbiosis and PJI was performed on patients that had next-generation sequencing done as part of their workup. Gut permeability and dysbiosis were measured using known biomarkers such as Zonulin. Statistical analysis consisted of descriptive statistics and logistic regression modeling. RESULTS: Among the cohort of 46 (47.8% female) patients, with a mean age of 68.47 years (range, 40 to 91) and a mean BMI 31.15 ± 6.49 kg/m2, 38 patients underwent a revision for PJI (29 chronic and 9 acute infections), and 8 patients were classified as aseptic failures. Then, a review of each of the bacteria retrieved was performed. Those known to be gut commensal based on available literature were noted. When regression modeling was performed, Zonulin levels were found to be associated with an increased probability of a similar finding (Estimate: 0.377, OR: 1.458; P = .001). CONCLUSION: In our study, we report the first clinical evidence of the translocation of bacteria from the gut to the joint in patients with PJI. In particular, when evaluating the microbiological profile of the NGS signal, a great number of known gut commensals were seen in patients with a highly permeable dysbiotic gut. Manipulation of the gut microbiome may become part of an essential and comprehensive approach for management of patients with PJI.

Increased Rates of Tibial Aseptic Loosening in Primary Cemented Total Knee Arthroplasty With a Short Native Tibial Stem Design.

BACKGROUND: Emerging evidence has suggested that both obesity and a short, native tibial stem (TS) design may be associated with early aseptic loosening in total knee arthroplasty. The use of short, fully cemented stem extensions may mitigate this risk. As such, we devised a multicenter study to confirm or negate these claims. METHODS: A search of our institutional research databases was done. A minimum 2-year time from index procedure was selected. Cohorts were created according to patient body mass index and the presence (stemmed tibia [ST]) or absence (nonstemmed tibia [NST]) of a short TS extension. Kaplan-Meier survival analyses for aseptic loosening and log-rank tests were done. RESULTS: A total of 1,350 patients were identified (ST = 500, NST = 850). The mean time to the final follow-up in cases without aseptic loosening for the ST cohort was 3.5 years (2.8-6.3) and 5.0 years (2.9-6.3) for the NST cohort (P < 0.001). Kaplan-Meier survival analysis at 6 years was superior for the ST cohort (100%, 98.5%; P = 0.025), and a trend toward superior 5-year survival was observed for body mass index <40 kg/m2 (99.1%, 93.2%; P = 0.066). The mean time to aseptic loosening was 2.4 years (0.9-4.5), with approximately 40% occurring within the first 2 years. CONCLUSIONS: Short, native TS design is associated with early aseptic loosening in primary cemented total knee arthroplasty. This can be mitigated through the use of an ST. More cost-effective solutions include (1) use of implants with longer native stem designs or (2) redesign of short TS implants.

Aspirin Administered for Venous Thromboembolism Prophylaxis May Protect Against Stiffness Following Total Knee Arthroplasty.

BACKGROUND: Aspirin has become the main agent for venous thromboembolism (VTE) prophylaxis following total knee arthroplasty (TKA). This study assessed whether aspirin is associated with less knee stiffness compared to warfarin and other chemoprophylaxis agents. METHODS: This is a retrospective review of all primary and revision TKAs performed between January 2009 and October 2020 at a high volume institution. Demographics, comorbidity data, and operative variables were extracted from medical records. VTE prophylaxis administered during this time period included aspirin, warfarin, and "others" (factor Xa, unfractionated heparin, low-molecular-weight heparin, fondaparinux, adenosine diphosphate receptor inhibitor, and direct thrombin inhibitor). The primary outcome assessed was manipulation under anesthesia (MUA) performed within 6 months of index surgery. Secondary outcome included major bleeding events. Univariate followed by multivariate regression analyses were performed. RESULTS: A total of 15,903 cases were included in the study, of which 531 (3.3%) patients developed stiffness that required MUA. The rates of MUA were 2.7% (251/9223) for patients receiving aspirin, 4.2% (238/5709) for patients receiving warfarin, and 4.3% (42/971) for all others (P's < .001). Multivariate regression analysis confirmed that aspirin is associated with lower rates of VTE compared to warfarin (adjusted odds ratio 1.423, 95% confidence interval 1.158-1.747, P < .001) and compared to other anticoagulation medications (adjusted odds ratio 1.742, 95% confidence interval 1.122-2.704, P = .013). Major bleeding events were also significantly lower in patients who received aspirin compared to the other 2 groups (P's = .001). CONCLUSION: Aspirin prophylaxis is associated with lower rates of MUA following TKA compared to warfarin and other VTE chemoprophylactic agents when grouped together.

Aspirin Is an Effective Prophylaxis for Venous Thromboembolism in Ambulatory Patients with Femoral Neck Fracture Undergoing Hip Arthroplasty.

BACKGROUND: Although aspirin has been adopted as an effective and safe prophylaxis against venous thromboembolism (VTE) by the arthroplasty community, the role of aspirin in the prevention of VTE in the setting of arthroplasty for trauma remains insufficiently known. Therefore, the present multicenter study investigated the efficacy of aspirin as VTE prophylaxis for patients with femoral neck fracture undergoing total hip arthroplasty or hemiarthroplasty. METHODS: We reviewed the medical records of 1,141 patients with femoral neck fracture who underwent total hip arthroplasty or hemiarthroplasty from 2008 to 2018 at 3 different institutions. Data on patient demographic characteristics, body mass index, history of VTE, and comorbidities were obtained from an electronic chart query and were confirmed by reviewing the medical records manually. Patients were allocated to cohorts based on the type of prophylaxis administered: aspirin (n = 454) and other anticoagulants (n = 687). Patients were then propensity score-matched on the basis of the risk score calculated using a previously validated tool and the remaining confounding variables. The primary outcome was the development of symptomatic VTE, namely deep vein thrombosis (DVT) or pulmonary embolism (PE) confirmed by appropriate imaging, within 90 days after the surgical procedure. A bivariable analysis was performed. RESULTS: The overall VTE rate was 1.98% for patients who received aspirin compared with 6.7% for patients who received other anticoagulants (p < 0.001). After propensity score matching and regression modeling, aspirin was found to be noninferior to more potent anticoagulation in preventing VTE after both total hip arthroplasty and hemiarthroplasty. CONCLUSIONS: Aspirin is an effective option for VTE prophylaxis in patients with femoral neck fracture who undergo hip arthroplasty. Based on the patient management benefits of aspirin for elective arthroplasty and the present study, we suggest its use in standard-risk ambulatory patients. LEVEL OF EVIDENCE: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Fungal periprosthetic joint infection: Rare but challenging problem.

Periprosthetic joint infection (PJI) is the most difficult complication following total joint arthroplasty. Most of the etiological strains, accounting for over 98% of PJI, are bacterial species, with Staphylococcusaureus and Coagulase-negative staphylococci present in between 50% and 60% of all PJIs. Fungi, though rare, can also cause PJI in 1%-2% of cases and can be challenging to manage. The management of this uncommon but complex condition is challenging due to the absence of a consistent algorithm. Diagnosis of fungal PJI is difficult as isolation of the organisms by traditional culture may take a long time, and some of the culture-negative PJI can be caused by fungal organisms. In recent years, the introduction of next-generation sequencing has provided opportunity for isolation of the infective organisms in culture-negative PJI cases. The suggested treatment is based on consensus and includes operative and non-operative measures. Two-stage revision surgery is the most reliable surgical option for chronic PJI caused by fungi. Pharmacological therapy with antifungal agents is required for a long period of time with antibiotics and included to cover superinfections with bacterial species. The aim of this review article is to report the most up-to-date information on the diagnosis and treatment of fungal PJI with the intention of providing clear guidance to clinicians, researchers and surgeons.

Inflammatory Bowel Diseases Increase the Risk of Periprosthetic Joint Infection.

BACKGROUND: A large body of evidence is emerging to implicate that dysregulation of the gut microbiome (dysbiosis) increases the risk of surgical site infections. Gut dysbiosis is known to occur in patients with inflammatory bowel disease (IBD), allowing for translocation of bacteria across the inflamed and highly permeable intestinal mucosal wall. The null hypothesis was that IBD was not associated with an increased risk of periprosthetic joint infection (PJI) after primary total hip and knee arthroplasty. METHODS: A matched cohort study was designed. The primary end point was the occurrence of PJI at 2 years postoperatively. The secondary end points were aseptic revisions at 2 years postoperatively, discharge to a rehabilitation facility, complications up to 30 days after total joint arthroplasty, and readmission up to 90 days after total joint arthroplasty. The International Classification of Diseases, Ninth Revision (ICD-9) and Tenth Revision (ICD-10) codes were used to identify patients with IBD and the control cohort. A chart review was performed to confirm the diagnosis of IBD. Using our institutional database, 152 patients with IBD were identified and matched (3:1) for age, sex, body mass index, year of surgical procedure, Charlson Comorbidity Index, and involved joint with 456 patients without IBD undergoing total joint arthroplasty. RESULTS: The cumulative incidence of PJI was 4.61% for the patients with IBD compared with 0.88% for the control cohort (p = 0.0024). When univariable Cox regression was performed, a diagnosis of IBD was found to be an independent risk factor for PJI (hazard ratio [HR], 5.44 [95% confidence interval (CI), 1.59 to 18.60]; p = 0.007) and aseptic revisions (HR, 4.02 [95% CI, 1.50 to 10.79]; p = 0.006). The rate of postoperative complications was also higher in patients with IBD. CONCLUSIONS: Based on the findings of this study, it appears that patients with IBD are at higher risk for treatment failure due to PJI or aseptic loosening after primary total joint arthroplasty. The exact reason for this finding is not known, but could be related to bacterial translocation from the inflamed intestinal mucosa, the dysregulated inflammatory status of these patients, malnutrition, and potentially other factors. Some of the aseptic failures could be as a result of infection that may have escaped detection and/or recognition. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Aspirin Thromboprophylaxis Is Associated With Less Major Bleeding Events Following Total Joint Arthroplasty.

BACKGROUND: There is ongoing debate on what is optimal prophylactic agent to reduce venous thromboembolism (VTE) following total joint arthroplasty (TJA). Although many studies assess the efficacy of these agents in VTE prevention, no attention is given to their adverse effect on major bleeding events (MBEs). This study compared the incidence of MBE in patients receiving aspirin as VTE prophylaxis vs other chemoprophylaxis. METHODS: A single-institution, retrospective study of 35,860 patients undergoing TJA between 2009 and 2020 was conducted. Demographic variables, co-morbidities, type of chemoprophylaxis, and intraoperative factors were collected. MBE was defined using the 2010 criteria for major bleeding in surgical patients presented by the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis. To enhance capture rate, comprehensive queries utilizing MBE keywords were conducted in clinical notes, physician dictations, and phone call logs. Univariate followed by multivariate regression was performed as well as propensity score matched analysis. RESULTS: Overall, 270 patients (0.75%) in this cohort developed MBE. The MBE rate was 0.5% in the aspirin group and 1.2% in the non-aspirin group. After adjusting for confounders, multiple logistic regression and propensity score matched analysis revealed almost 2 times lower odds of MBE in patients who received aspirin. Variables independently associated with increased MBE risk included increasing age, body mass index, American Society of Anesthesiologists score, revision surgery, peptic ulcer disease, coagulopathy, intraoperative blood transfusion, and active smoking. CONCLUSION: Administration of aspirin for VTE prophylaxis, compared to other chemoprophylaxis agents may have an association with lower risk of major bleeding following TJA. Future randomized controlled trials should examine these findings.

Ceramic-on-polyethylene hip arthroplasty reduces the risk of postoperative periprosthetic joint infection.

Metal-on-polyethylene (MoP) total hip arthroplasty (THA) prostheses are known to release metal debris. Basic science studies suggest that metal implants induce a pro-inflammatory response that ultimately chemoattracts leukocytes including macrophages and neutrophils to the surgical site. This raises concern of higher risk of infection with these prostheses through the "trojan horse" mechanism by which neutrophils and macrophages transport intracellular pathogens from a remote site. This study compared the infection occurrence between MoP and ceramic-on-polyethylene (CoP) implants to determine if a higher infection rate in MoP is present. We reviewed a consecutive series of 6052 CoP and 4550 MoP primary THA patients from 2015 to 2019. The occurrence of periprosthetic joint infection at 2 years was defined according to the 2018 ICM definition. Statistical analysis consisted of descriptive statistics, univariate analysis, and regression modeling. When compared to CoP, MoP patients were older, included more females, had a higher body mass index, and more commonly affected by comorbidities according to Elixhauser's score. Total revisions were higher in the MoP group (3.19% vs. 2.41%) The absolute incidence of PJI was higher in MoP (2.40% vs. 1.64%). When we adjusted for confounding factors, MoP was found independently associated with a higher PJI risk. Despite MoP and CoP both being widely used for primary THA, we found a higher incidence of PJI in MoP patients. The association remained significant when controlled for possible confounders. We hypothesize that leukocyte recruitment to these implants may play a role and should be further investigated.

Tendon healing is adversely affected by low-grade inflammation.

BACKGROUND: Tendinopathy is common, presents with pain and activity limitation, and is associated with a high risk of recurrence of the injury. Tendinopathy usually occurs as a results of a disrupted healing response to a primary injury where cellular and molecular pathways lead to low grade chronic inflammation. MAIN FINDINGS: There has been a renewed interest in investigating the role of Inflammation in the pathogenesis of tendinopathy, in particular during the initial phases of the condition where it may not be clinically evident. Understanding the early and late stages of tendon injury pathogenesis would help develop new and effective treatments addressed at targeting the inflammatory pathways. CONCLUSION: This review outlines the role of low-grade Inflammation in the pathogenesis of tendinopathy, stressing the role of proinflammatory cytokines, proteolytic enzymes and growth factors, and explores how Inflammation exerts a negative influence on the process of tendon healing.

Emergence of Antibiotic Resistance Across Two-Stage Revision for Periprosthetic Joint Infection.

BACKGROUND: The current preferred treatment for chronic hip and knee periprosthetic joint infection (PJI) involves both surgical intervention and antibiotic treatment as part of a two-stage revision. The purpose of this study is to determine how often patients who underwent a two-stage revision for chronic PJI developed a subsequent antibiotic-resistant infection. METHODS: We retrospectively reviewed the clinical records of 142 patients who underwent a two-stage revision for a chronic culture-positive PJI from January 2014 to May 2019. Demographic data and risk factors for PJI were identified. Resistance was defined in accordance with microbiology laboratory report and minimum inhibitory concentration. Statistical analysis consisted of descriptive statistics and univariate analysis. RESULTS: Only 10 of the 142 patients (7.04%) demonstrated emergence of resistance to antibiotics across their two-stage revision. At reimplantation, 25 (17.6%) patients had positive cultures. Of these, 16 patients presented with a novel organism and 9 patients had positive culture for the same organism as the initial infection. During the entire course of the two-stage revision, including spacer exchanges and irrigation and debridement procedures, 15 (10.56%) patients demonstrated persistent infections, whereas 25 (17.6%) patients presented with novel infections. 26 (18.3%) patients had reinfection of the same joint within one year. CONCLUSION: In the given cohort, there does not appear to be a major emergence of antibiotic resistant organisms in patients undergoing two-stage exchange arthroplasty and antibiotic treatment.

Low Incidence of Asymptomatic Positive Patients Detected During Preoperative Testing for Total Joint Arthroplasty During the COVID-19 Pandemic.

INTRODUCTION: Although the pause in elective surgery was necessary to preserve healthcare resources at the height of the novel coronavirus disease 2019 (COVID-19) pandemic, recent data have highlighted the worsening pain, decline in physical activity, and increase in anxiety among cancelled total hip and knee arthroplasty patients. The purpose of this study was to evaluate the effectiveness of our staged reopening protocol and the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among elective arthroplasty patients. METHODS: We identified all elective hip and knee arthroplasty patients who underwent our universal COVID-19 testing protocol during our phased reopening between May 1, 2020, and July 21, 2020, at our institution. We recorded the SARS-CoV-2 test results of each patient along with their demographics, medical comorbidities, and symptoms at the time of testing. We followed each of these positive patients through their rescheduled cases and recorded any complications or potential SARS-CoV-2 healthcare exposures. RESULTS: Of the 2,329 patients, we identified five patients (0.21%) with a reverse transcription-polymerase chain reaction--confirmed SARS-CoV-2 positive test, none with symptoms. All patients were successfully rescheduled and underwent their elective arthroplasty procedure within 6 weeks of their original surgery date. None of these patients experienced a perioperative complication at the time of their rescheduled arthroplasty procedure. No orthopaedic surgeon or staff member caring for these patients reported a positive SARS-CoV-2 test. CONCLUSION: Our phased reopening protocol with universal preoperative virus testing was safe and identified a low incidence of SARS-CoV-2 among asymptomatic, elective arthroplasty patients at our institution. With uncertainty regarding the trajectory of the COVID-19 pandemic, we hope that this research can guide future policy decisions regarding elective surgery.

Emergency Department Visits After Total Joint Arthroplasty for Concern for Deep Vein Thromboses.

BACKGROUND: Concern for deep vein thrombosis (DVT) is the most common reason for emergency department (ED) referral after total joint arthroplasty (TJA) at our institution. We aim to investigate the referral pathway, together with the cost and outcomes associated with patients who access an ED because of concern for DVT after TJA. METHODS: We reviewed a consecutive series of all primary hip and knee arthroplasty patients who accessed the ED for concern for DVT within 90 days of surgery over a one-year period. The referral source and costs associated with the ED visit were collected. A propensity-matched control cohort (n = 252) that was not referred to the ED for DVT was used to compare patient-reported outcomes measures. RESULTS: In 2018, 108/10,445 primary TJA patients (1.0%) accessed the ED for concern about DVT. The most common reason for accessing the ED was self-referral (69, 64%), followed by orthopaedic on-call referral (21, 19%). Only 15 patients (14%) were found to have ultrasonography evidence of DVT. The mean cost for accessing the ED for DVT for patients with public insurance was $834 (range $394-$2,877). When compared with the control cohort, patients who accessed the ED for DVT had significantly lower postoperative functionality scores (52.5 versus 65.9, P < 0.001). DISCUSSION: At our institution, 1% of patients who undergo primary TJA accessed the ED for concern for DVT at substantial cost, with only a small portion testing positive for DVT. Self-referral is by far the most common pathway. Additional investigations will be aimed at determining better pathways for DVT work-up, while ensuring appropriate management.