Aspirin and the prevention of venous thromboembolism following total joint arthroplasty: commonly asked questions

Venous Thromboembolism Prophylaxis After Revision Hip Arthroplasty: A Multicenter Analysis of Anticoagulant Choice and Weight-Bearing Status

INTRODUCTION

Aspirin (ASA) is a reliable prophylactic agent for venous thromboembolism (VTE) in revision total hip arthroplasty (THA). While several studies have compared ASA to other anticoagulants, to our knowledge, none have evaluated its effectiveness in patients who have restricted weight-bearing status (WBS). Limited mobilization after surgery increases the risk of VTE complications. This study aimed to assess the effects of WBS and anticoagulant choice on the rates of thrombotic and bleeding complications after revision of THA.

METHODS

We reviewed 3,000 revision THAs performed between 2019 and 2022 across four institutions. Data collected included demographic factors, comorbidities, indication for revision, weight-bearing status (weight bearing as tolerated [WBAT] versus non-WBAT), anticoagulant choice, and Caprini VTE risk assessment score. Incidences of VTE, deep vein thrombosis (DVT), pulmonary embolism (PE), drainage, hematoma, and periprosthetic joint infections (PJI) were recorded. Multivariate logistic regression was used to evaluate the associations between postoperative thrombotic and bleeding events, prophylactic pharmacologic agents, and weight-bearing status.

RESULTS

The incidence of VTE, DVT, and PE was significantly lower in the ASA cohort compared to the non-ASA cohort (VTE: 1.2 versus 3.5%, P < 0.001; DVT: 0.9 versus 3.3%, P < 0.001; PE: 0.2 versus 0.9%, P < 0.001). Within the ASA cohort, the incidence of VTE (1.1 versus 1.1%), bleeding complications (4.5 versus 4.5%), and PJI (5.1 versus 5.8%) were similar when stratified by WBAT and non-WBAT. Multivariate regression demonstrated that ASA prophylaxis decreased the likelihood of VTE compared to non-ASA (OR [odds ratio]: 0.35, CI [confidence interval]: 0.19 to 0.57, P < 0.001). Weight-bearing status was not a risk factor regarding VTE or bleeding events.

CONCLUSION

Aspirin is a safe and effective prophylactic option for VTE in revision THA, regardless of WBS. While the lower VTE incidence in the ASA group suggests efficacy, potential selection bias must be considered.

Statin Use Is Associated With Decreased Venous Thromboembolism Events Following Total Hip Arthroplasty: A Matched Retrospective Cohort Study

BACKGROUND

Despite advances in surgical techniques and postoperative prophylactic protocols, venous thromboembolism (VTE) events remain an important source of morbidity following total hip arthroplasty (THA). Prior research in cardiology and other surgical fields has suggested that statin medications may have a protective effect against VTE. Our study aimed to: (1) assess if preoperative statin use was associated with decreased rates of VTE following THA; and (2) conduct a subgroup analysis of statin intensity and VTE events.

METHODS

A total of 1,154 patients who had preoperative statin use for at least four weeks before surgery and who underwent primary THA at a large, urban academic center between January 1, 2012, and June 1, 2023, were identified. The 90-day postoperative VTE events, deep vein thrombosis, pulmonary embolism, emergency department visits, reoperations, and readmission rates were collected from institutional coding software. Mortality rate in the 90-day postoperative period was also measured. Propensity matching was used to control for demographics and selected comorbidities.

RESULTS

Preoperative statin use was associated with significantly lower rates of 90-day VTE events (Statin: 0.43% versus No-Statin: 1.13%, P = 0.047). There were no significant differences in 90-day PE, deep vein thrombosis, emergency department visit, readmission, or reoperation rates. There were no deaths within 90 days of THA in either group. Subgroup analysis of statin intensity revealed no significant differences in any outcomes measured between high-intensity, medium-intensity, and low-intensity statin groups.

CONCLUSIONS

Preoperative statin use is associated with significantly lower rates of VTE events in the 90-day postoperative period following THA. Further research into the effect of statins on post-THA VTE is warranted.

Predictors and risk factors of pulmonary embolism after total hip arthroplasty: an NSQIP study

INTRODUCTION

Pulmonary embolism (PE) is a well-known contributor to morbidity after total hip arthroplasty (THA). Considerable efforts have been invested in reducing PE occurrence through pharmacological and perioperative interventions. Nonetheless, the effectiveness of these strategies in reducing the incidence and overall mortality associated with pulmonary embolism events remains a matter of debate. Therefore, identifying risky patients has been gaining importance.

METHODS

We utilised data from the National Surgical Quality Improvement Program (NSQIP) participant usage file (PUF) database spanning the years 2016 to 2021. All preoperative parameters were analysed with chi-square afterwards, meaningful ones were run with logistic regression test.

RESULTS

A study examined factors influencing pulmonary embolism (PE) prevalence in 235,393 total hip arthroplasty patients. Univariate analysis identified significant associations between PE and female gender, diabetes, smoking, dyspnea, CHF, COPD, hypertension (HT), bleeding disorders, disseminated cancer, steroid use, and functional health status. Multivariate analysis revealed male gender as protective, while COPD, hypertension, and disseminated cancer increased PE risk. Notably, smoking appeared protective. PE patients had higher return-to-operation rates (41.7% vs. 2.2%) but similar 30-day mortality (0.2% vs. 0.04%), though mortality's odds ratio was not significant.

CONCLUSIONS

Our findings suggest that certain patient characteristics, such as COPD and metastatic malignancy, significantly influence the likelihood of PE development.

Comparison of low molecular weight heparin, aspirin, and their combination for the prevention of thrombosis after total knee arthroplasty in obese patients

Purpose

Patients undergoing total knee arthroplasty (TKA) are at a high risk of thromboembolic events, which is higher in obese patients. Determining the appropriate prophylaxis for venous thromboembolism (VTE) in obese patients is challenging. Therefore, we aimed to compare the effects of low molecular weight heparin (LMWH) with aspirin (ASA) and their combination for the prevention of thromboembolic events after TKA in obese patients.

Methods

In a retrospective study, 245 obese patients with BMIs over 30 who underwent TKA were enroled. Eligible patients were divided into three groups: Group A was given LMWH sodium (Clexane®) for 14 days, Group B was given ASA for 14 days, and Group C was given LMWH sodium (Clexane®) for 5 days and then ASA twice daily for the days between 5 and 14 postoperatively. The primary outcome was the incidence of VTE within three months. Secondary outcomes included routine laboratory evaluations (PT, PTT, INR, Hb, Hct, platelets, BUN and Cr) and adverse effects of ASA and LMWH, such as bleeding, anaemia, thrombocytopenia, and gastrointestinal or neurological symptoms.

Results

Regarding the incidence of DVT and PTE, we did not observe significant differences between groups (p > 0.05). A total of seven symptomatic VTE was observed in six patients. We observed two cases with PE who were in the Clexane group. Moreover, five individuals had DVT in the follow-up: three cases in the Clexane group, one in the ASA group, and one in the ASA + Clexane group, which was not statistically significant (p > 0.05). There were no differences between groups regarding the risk of adverse events and complications.

Conclusion

We found that ASA is not inferior to enoxaparin in reducing VTE after TKA in obese patients. Therefore, given ASA's low cost and greater convenience, it may be considered a reasonable alternative for extended VTE prophylaxis for TKA surgery in obese patients.

Level of Evidence

Level III.

Efficacy and safety of aspirin in preventing venous thromboembolism after hip arthroplasty for femoral neck fracture: a noninferiority prospective cohort study

BACKGROUND

Venous thromboembolism (VTE) is a common complication after hip arthroplasty. Here, we investigated the clinical efficacy and safety of prophylactic aspirin vs. conventional therapy in hip arthroplasty for femoral neck fracture.

METHODS

Patients who underwent total hip arthroplasty and hemiarthroplasty for femoral neck fractures between April 2021 and April 2024 were prospectively enrolled. Group A received oral aspirin (100 mg, once daily) as VTE prophylaxis; Group LR received low-molecular-weight heparin (4,250 U, once daily) sequentially followed by rivaroxaban (10 mg, once daily). The patients were followed up for 90 days postoperatively. Safety and efficacy were comprehensively evaluated based on postoperative VTE incidence, laboratory blood tests, bleeding events, and other complications.

RESULTS

Group A was noninferior to Group LR in preventing VTE (incidence rates of 11.6% and 10.1%, respectively, with a rate difference of 1.5%, 95% CI: 0.7-2.3%, P for non-inferiority test = 0.017). There was no significant difference between the groups in the incidence of bleeding events (3.3 vs. 8.4%; P = 0.092). Furthermore, the rates of other complications did not differ significantly between groups.

CONCLUSION

In patients undergoing hip arthroplasty for femoral neck fractures, the efficacy and safety of oral aspirin for preventing VTE was similar to that of low-molecular-weight heparin followed by rivaroxaban.

Low-versus high-dose aspirin for venous thromboembolic prophylaxis after total joint arthroplasty: a systematic review and meta-analysis

BACKGROUND

The adverse effects of aspirin are dose-dependent, and there is controversy surrounding the use of low-dose (LD) aspirin to prevent venous thromboembolism (VTE) following total joint arthroplasty (TJA). This meta-analysis sought to compare the efficacy and complication rate of low-dose (162 mg per day) versus high-dose (HD, 650 mg per day) aspirin after TJA surgery.

METHODS

In four main databases, we searched from inception until September 2024 for articles comparing the rate of VTE following TJA(TKA/THA) using only aspirin chemoprophylaxis with different dosages. We meta-analyzed and compared the VTE and complication rates of LD aspirin (162 mg per day) with HD aspirin (650 mg per day) and presented our results as odds ratio (ORs) in forest plot diagrams.

RESULTS

There were 14 eligible studies, comprising 43,518 patients in the LD group and 62,645 patients in the HD group. DVT (OR: 1.37, CI: 0.93-2.02, P = 0.11) and PE (OR: 1.86, CI: 0.73-4.72, P = 0.19) rates were similar between the groups. However, taking VTE as the total number of cases with DVT or PE, the incidence was significantly higher in the HD group than in the LD group (OR:1.53, CI: 1.17-2.00, P = 0.002). HD also had a significantly higher rate of PJI (OR:2.68 CI:1.5-4.6 P = 0.001), but gastrointestinal bleeding (GIB) was similar between the two groups (OR: 0.97, CI: 0.42-2.22, P = 0.95).

CONCLUSION

The findings suggest that LD aspirin may be a viable option for VTE chemoprophylaxis following TJA, potentially offering comparable efficacy with a lower risk of PJI compared to HD aspirin regimens.

LEVEL OF EVIDENCE

Therapeutic Level II.

Safety and Efficacy of Aspirin Compared to Enoxaparin Following Total Hip and Total Knee Arthroplasty Among Patients Who Have a History of Venous Thromboembolic Disease

BACKGROUND

Despite the broad utilization of aspirin (ASA) as a venous thromboembolism (VTE) chemoprophylactic agent following total knee arthroplasty (TKA) and total hip arthroplasty (THA), few studies have evaluated its safety and efficacy in patients who had a history of VTE. This study sought to evaluate the safety and efficacy of ASA relative to enoxaparin in high-risk total joint arthroplasty patients.

METHODS

An all-payer claims database was queried for primary, elective THA, and TKA patients from January 2015 to December 2021. Patients who had a history of VTE were divided based on receipt of either ASA or enoxaparin as VTE prophylaxis. In a 1:1 ratio, 1,429 THA and 2,864 TKA high-risk ASA patients were matched to high-risk enoxaparin patients on age, sex, race, and presence of pertinent comorbidities. Multivariable regression analyses accounted for potential confounders.

RESULTS

After multivariable analyses, similar risk of pulmonary embolism (THA: adjusted odds ratio [aOR]: 0.85, 95% confidence interval [CI]: 0.26 to 2.76; TKA: aOR: 0.71, 95% CI: 0.38 to 1.32) and deep vein thrombosis (DVT) (THA: aOR: 1.12, 95% CI: 0.53 to 2.36) was observed in the ASA cohorts relative to the enoxaparin cohorts. TKA patients in the ASA cohort had a lower risk of DVT than those in the enoxaparin cohort (aOR: 0.57, 95% CI: 0.33 to 0.96). THA ASA patients demonstrated a reduced risk of stroke (aOR: 0.03, 95% CI: 0.00 to 0.73), while TKA ASA patients had a lower risk of acute blood loss anemia (aOR: 0.77, 95% CI: 0.66 to 0.88).

CONCLUSIONS

High-risk patients who received ASA demonstrated similar risk of pulmonary embolism and DVT, but decreased risk of bleeding-related and medical complications compared to patients who received enoxaparin. The utilization of ASA in high-risk patients was not associated with an increased risk of adverse outcomes.

Medication effects on pulmonary thromboembolism in mice intravenously transplanted with canine adipose tissue-derived mesenchymal stem cells

IMPORTANCE

The intravenous administration of adipose tissue-derived mesenchymal stem cells (AdMSCs) in veterinary medicine is a promising regenerative therapy, but it can lead to severe complications, including pulmonary thromboembolism (PTE).

OBJECTIVE

As part of an ongoing study, this study examined the impact of medications, such as heparin, aspirin, and sodium nitroprusside (SNP), on the factors linked to PTE after an intravenous injection of canine mesenchymal stem cell into experimental animals.

METHODS

Fluorescently labeled canine AdMSCs were administered intravenously into the tail veins of five-week-old male BALB/c hairless mice. This study compared the survival rates, biodistribution, platelet counts, D-dimer levels, and histological examination results among the drug treatment experimental and the control groups.

RESULTS

The final survival rates in the SNP, control aspirin, and heparin groups were 25%, 33%, 50%, and 100%, respectively. Ex vivo imaging confirmed fluorescence exclusively in the lungs of all subjects who died during the injection, with no fluorescence detected in the other organs. On the other hand, in the heparin experimental group, the surviving individuals exhibited fluorescence in the lungs and the liver on day one. Histological biopsies revealed PTE in all deceased individuals within the medication experimental groups (p = 0.029).

CONCLUSIONS AND RELEVANCE

Heparin was highly effective, with no PTE-related deaths observed when used alongside cell injections. Aspirin revealed moderate effectiveness, surpassing the control group. On the other hand, the efficacy of SNP was inferior to that of the other two drugs.

Aspirin as Venous Thromboembolism Prophylaxis in Arthroplasty Patients: An Analysis of Clinical Practice Guidelines Recommendations

BACKGROUND

Venous thromboembolism (VTE) is a recognized postoperative complication of hip or knee arthroplasty and incurs major morbidity and mortality. While anticoagulants are the mainstay of chemoprophylaxis, aspirin has recently emerged as a popular prophylactic agent. However, there is a lack of high-quality evidence comparing aspirin to anticoagulants as a method of VTE prophylaxis, and current guidelines are conflicting regarding using aspirin as first-line chemoprophylaxis. We aimed to investigate guideline characteristics that are associated with the recommendation for or against aspirin as a first-line agent.

METHODS

MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, and PubMed databases were searched from 1966 to January 2024 to identify clinical practice guidelines for VTE prophylaxis in adult hip or knee arthroplasty inpatients of average risk. The characteristics of the guideline were collected by 2 independent reviewers. Logistic regression was used to test the association between the recommendation for or against aspirin and guideline characteristics.

RESULTS

There were 26 guidelines published from February 2003 to September 2023 and included in this study. There were 5 guidelines that recommended aspirin and 11 guidelines that recommended against aspirin as first-line therapy. With a more recent year of publication, aspirin was more likely to be recommended (odds ratio 1.72, 95% confidence interval: 1.05 to 2.84) and less likely to be recommended against (odds ratio 0.61, 95% confidence interval: 0.41 to 0.90). No other variables, including the level of evidence used, the composition of the guideline working group, or the objective of the guideline, were associated with the recommendation for or against aspirin.

CONCLUSIONS

Guidelines were inconsistent in their recommendations regarding aspirin as first-line therapy as VTE prophylaxis in arthroplasty patients. Adequately powered randomized controlled trials using modern practices, such as early postoperative mobilization, are needed to better inform clinical practice guidelines.

Low-Dose Enteric-Coated and Chewable Aspirin Are Not Equally Effective in Preventing Venous Thromboembolism in Total Knee and Hip Arthroplasty

BACKGROUND

Low-dose aspirin is an effective venous thromboembolism (VTE) prophylactic medication in primary total joint arthroplasty, but the efficacy and safety of the formulations of chewable and enteric-coated aspirin have not been compared. The purpose of this study was to investigate the VTE and gastrointestinal (GI) complication rates of chewable and enteric-coated 81 mg aspirin bis in die for VTE prophylaxis in primary total joint arthroplasty.

METHODS

A retrospective, single-institution cohort study was performed on patients who underwent primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) from 2017 to 2021. Comparisons were made between 4,844 patients who received chewable, noncoated aspirin 81 mg and 4,388 patients who received enteric-coated 81 mg aspirin. Power analysis demonstrated 1,978 and 3,686 patients were needed per group to achieve a power of 80% for 90-day VTE rates (using inferiority testing) and GI complications (using superiority testing), respectively. Patients had similar baseline characteristics. Statistical analyses were done using t-tests and Chi-squared tests, with statistical significance defined as a P value < .05.

RESULTS

There were no significant differences in the incidences of postoperative VTE (0.31% versus 0.55%; P = .111) or GI complications (0.14% versus 0.14%; P = 1.000) between patients who received either chewable or enteric-coated 81 mg aspirin bis in die in the overall comparison that included both THA and TKA patients combined, or THA patients alone. However, the VTE incidence for TKA patients alone was significantly lower with chewable than enteric-coated aspirin (0.22% versus 0.62%; P = .037), with no difference in GI complications (0.13% versus 0.19%; P = .277).

CONCLUSIONS

Low-dose aspirin in enteric-coated formulation is inferior to chewable aspirin for VTE prophylaxis in primary TKA, but not inferior in THA patients. Both formulations have a similar GI complication rate. Therefore, it is reasonable to consider a transition from enteric-coated to uncoated chewable low-dose aspirin.

Efficacy and safety of commonly used thromboprophylaxis agents following hip and knee arthroplasty

Aims

We investigated the efficacy and safety profile of commonly used venous thromboembolism (VTE) prophylaxis agents following hip and knee arthroplasty.

Methods

A systematic search of PubMed, Embase, Cochrane Library, Web of Science, and OrthoSearch was performed. Prophylaxis agents investigated were aspirin (< 325 mg and ≥ 325 mg daily), enoxaparin, dalteparin, fondaparinux, unfractionated heparin, warfarin, rivaroxaban, apixaban, and dabigatran. The primary efficacy outcome of interest was the risk of VTE, whereas the primary safety outcomes of interest were the risk of major bleeding events (MBE) and wound complications (WC). VTE was defined as the confirmed diagnosis of any deep vein thrombosis and/or pulmonary embolism. Network meta-analysis combining direct and indirect evidence was performed. Cluster rank analysis using the surface under cumulative ranking (SUCRA) was applied to compare each intervention group, weighing safety and efficacy outcomes.

Results

Of 86 studies eligible studies, cluster rank analysis showed that aspirin < 325 mg daily (SUCRA-VTE 89.3%; SUCRA-MBE 75.3%; SUCRA-WC 71.1%), enoxaparin (SUCRA-VTE 55.7%; SUCRA-MBE 49.8%; SUCRA-WC 45.2%), and dabigatran (SUCRA-VTE 44.9%; SUCRA-MBE 52.0%; SUCRA-WC 41.9%) have an overall satisfactory efficacy and safety profile.

Conclusion

We recommend the use of either aspirin < 325 mg daily, enoxaparin, or dabigatran for VTE prophylaxis following hip and knee arthroplasty.

Risk Factors Associated with Thromboembolic Complications After total Hip Arthroplasty: An Analysis of 1,129 Pulmonary Emboli

INTRODUCTION

Venous thromboembolism (VTE) remains a dangerous complication after total hip arthroplasty (THA), despite advances in chemoprophylactic measures. This study aimed to identify risk factors of developing pulmonary embolism (PE) and deep vein thrombosis (DVT) after THA using a modern cohort of patients reflecting contemporary practices.

METHODS

The Premier Healthcare Database was queried for primary, elective THAs from January 1st, 2015, to December 31st, 2021. Patients who developed PE or DVT within 90 days of THA were compared with patients who did not develop any postoperative VTE. Differences in patient demographics, comorbidities, hospital factors, perioperative medications, chemoprophylactic agents, and allogeneic blood transfusion were compared between cohorts. Multivariable logistic regression models were used to identify independent risk factors of PE and DVT. In total, 544,298 THAs were identified, of which 1,129 (0.21%) developed a PE and 1,799 (0.33%) developed a DVT.

RESULTS

Patients diagnosed with a PE had significantly higher rates of in-hospital death (2.6% vs 0.1%, P < 0.001) compared with those without a PE. Age (adjusted odds ratio: 1.02 per year, 95% confidence interval [CI]: 1.01 to 1.03) and Black race (aOR: 1.52, 95% CI: 1.24 to 1.87) were associated with an increased risk of PE. Comorbidities associated with increased risk of PE included chronic pulmonary disease (aOR: 1.58, 95% CI: 1.36 to 1.84), pulmonary hypertension (aOR: 2.06, 95% CI: 1.39 to 3.04), and history of VTE (aOR: 2.38, 95% CI: 1.98 to 2.86). Allogeneic blood transfusion (aOR: 2.40, 95% CI: 1.88 to 3.06) was also associated with an increased risk of PE while dexamethasone utilization was associated with a reduced risk (aOR: 0.83, 95% CI: 0.73 to 0.95).

DISCUSSION

Increasing age; Black race; allogeneic blood transfusion; and comorbidities, including chronic pulmonary disease, pulmonary hypertension, and history of VTE, were independent risk factors of PE after THA. Given the increased mortality associated with PE, patients should be carefully evaluated for these factors and managed with an appropriate chemoprophylactic regimen.

Perioperative Differences Between Outpatient and Inpatient Pathways Following Hip and Knee Arthroplasty

Background

Optimization of clinical pathways and logistics led to the introduction of outpatient joint arthroplasty of the hip and knee. Nevertheless, little is known about what these current protocols look like and how they differ from "standard" inpatient protocols. This study aimed to find preoperative, intraoperative, and postoperative differences between outpatient and inpatient pathways.

Methods

A questionnaire (ranging between 23 and 37 items) was developed and administered by email to orthopedic surgeons who were a member of the Dutch Hip Society and Dutch Knee Society. Survey response rate was 38% (N = 117).

Results

No significant differences were found in preoperative pathway characteristics. The administration regime for tranexamic acid significantly differed between outpatient and inpatient pathways (P < .001 and P = .002 for hip and knee arthroplasty, respectively), with outpatient pathways using a combined (eg, oral and intravenous) administration regime more frequently. The perioperative antibiotic prophylaxis regime also significantly differed between outpatient and inpatient pathways (P < .001 and P = .014, respectively), with outpatient pathways more frequently incorporating fewer antibiotic doses. Same-day postoperative mobilization significantly less often occurred if surgery took place later that day in inpatient hip arthroplasty pathways (24%; P = .034). Postoperative hemoglobin-check occurred significantly more often on indication in outpatient than in inpatient hip and knee arthroplasty pathways (∼75% vs ∼25%; P = .001).

Conclusions

Few intraoperative and postoperative differences in outpatient and inpatient pathways were found and probably mainly relied on logistical grounds. Nonetheless, findings suggested that outpatient pathways tended to be more up-to-date and innovative than inpatient pathways.

A Comparison between Enoxaparin and Aspirin in Preventing Deep Vein Thrombosis after Spine Surgery: A Randomized Clinical Trial

Objectives

Deep Vein Thrombosis (DVT) is a significant medical concern characterized by the formation of blood clots within the venous system. Surgical procedures are known to increase the risk of DVT. While enoxaparin has proven to be highly effective in treating DVT, concerns about bleeding and accurate dosage regulation may restrict its application. Recent research has focused on aspirin's potential in preventing DVT after various surgeries. This study aimed to determine whether aspirin was as effective as enoxaparin in preventing DVT after spine surgery.

Methods

This randomized controlled trial enrolled study patients who underwent spine surgery at Shahid Kamyab Emergency Hospital in Mashhad, and had a Caprini score > 5, indicating a higher risk of DVT. In the control group, patients received subcutaneous injections of enoxaparin at a dosage of 40 mg, while the intervention group received oral aspirin tablets with a daily dosage of 81 mg. An experienced radiologist performed a Doppler ultrasound of the lower limbs' veins seven days after surgery to diagnose DVT. The outcomes of the two groups were then compared.

Results

A total of 100 patients participated in the clinical trial and were equally assigned to the aspirin and enoxaparin groups. Both groups were homogeneous regarding the basic and clinical characteristics. The incidence of postoperative DVT was 4.0% in the aspirin group and 10.0% in the enoxaparin group (p=0.092). The incidence of hemorrhage was 2.0% in the aspirin group and 4.0% in the enoxaparin group (p=0.610).

Conclusion

These findings indicate that aspirin may be a promising alternative to enoxaparin for DVT prevention after surgery, but additional research is essential to validate these results and further assess the benefits and risks associated with aspirin usage in this context.

Current Evidence and Expert Opinion on Thromboprophylaxis After Total Knee and Hip Replacement

An effective anticoagulant provides a balance between the risk for venous thromboembolism (VTE) and bleeding and is crucial in achieving optimal clinical outcomes in patients undergoing total hip replacement (THR) and total knee replacement (TKR) surgeries. We performed a review of the literature on thromboprophylaxis for patients undergoing total hip or knee replacement. This review article summarizes current guidelines and evidence for anticoagulation along with the expert opinion about pharmacological VTE prophylaxis, particularly non-Vitamin K antagonist oral anticoagulants (NOACs), for patients after total hip or knee replacement. Aspirin for VTE prophylaxis after TKR/THR has been controversial and most of the evidence is reported from observational research. Although the guidelines do not recommend any specific thromboprophylaxis agent, available evidence suggests that NOACs are as effective as low molecular weight heparins (LMWHs) in preventing VTE. Oral administration and the lack of dose monitoring make NOACs easy to use in outpatient settings in cases with challenging treatment compliances. They can be used for two weeks after TKR and five weeks after THR - six weeks after TKR and THR to cover the at-risk period for VTE post-discharge. Owing to the lack of evidence for a head-to-head comparison of NOACs, an anticoagulant with better efficacy and safety may be suggested in special patient populations (elderly, obese patients, or those with renal dysfunction). The expert opinion on pharmacological VTE prophylaxis provided in this article could address some gaps in the management of anticoagulation in patients with total hip or knee replacement.

Venous Thromboembolism in Total Hip and Total Knee Arthroplasty

Importance

The optimal pharmacologic thromboprophylaxis agent after total hip and total knee arthroplasty is uncertain and consensus is lacking. Quantifying the risk of postoperative venous thromboembolism (VTE) and bleeding and evaluating comparative effectiveness and safety of the thromboprophylaxis strategies can inform care.

Objective

To quantify risk factors for postoperative VTE and bleeding and compare patient outcomes among pharmacological thromboprophylaxis agents used after total hip and knee arthroplasty.

Design, Setting, and Participants

This retrospective cohort study used data from a large health care claims database. Participants included patients in the United States with hip or knee arthroplasty and continuous insurance enrollment 3 months prior to and following their surgical procedure. Patients were excluded if they received anticoagulation before surgery, received no postsurgical pharmacological thromboprophylaxis, or had multiple postsurgery thromboprophylactic agents. In a propensity-matched analysis, patients receiving a direct oral anticoagulant (DOAC) were matched with those receiving aspirin.

Exposures

Aspirin, apixaban, rivaroxaban, enoxaparin, or warfarin.

Main Outcomes and Measures

The primary outcome was 30-day cumulative incidence of postdischarge VTE. Other outcomes included postdischarge bleeding.

Results

Among 29 264 patients included in the final cohort, 17 040 (58.2%) were female, 27 897 (95.2%) had inpatient admissions with median (IQR) length of stay of 2 (1-2) days, 10 948 (37.4%) underwent total hip arthroplasty, 18 316 (62.6%) underwent total knee arthroplasty; and median (IQR) age was 59 (55-63) years. At 30 days, cumulative incidence of VTE was 1.19% (95% CI, 1.06%-1.32%) and cumulative incidence of bleeding was 3.43% (95% CI, 3.22%-3.64%). In the multivariate analysis, leading risk factors associated with increased VTE risk included prior VTE history (odds ratio [OR], 5.94 [95% CI, 4.29-8.24]), a hereditary hypercoagulable state (OR, 2.64 [95% CI, 1.32-5.28]), knee arthroplasty (OR, 1.65 [95% CI, 1.29-2.10]), and male sex (OR, 1.34 [95% CI, 1.08-1.67]). In a propensity-matched cohort of 7844 DOAC-aspirin pairs, there was no significant difference in the risk of VTE in the first 30 days after the surgical procedure (OR, 1.14 [95% CI, 0.82-1.59]), but postoperative bleeding was more frequent in patients receiving DOACs (OR, 1.36 [95% CI, 1.13-1.62]).

Conclusions and Relevance

In this cohort study of patients who underwent total hip or total knee arthroplasty, underlying patient risk factors, but not choice of aspirin or DOAC, were associated with postsurgical VTE. Postoperative bleeding rates were lower in patients prescribed aspirin. These results suggest that thromboprophylaxis strategies should be patient-centric and tailored to individual risk of thrombosis and bleeding.

Role of aspirin in the prevention of heterotopic ossification following total hip replacement: a systematic review and meta-analysis

BACKGROUND

To systematically investigate if aspirin (ASA), used as venous thromboembolism (VTE) prophylaxis, plays a role in the prevention of heterotopic ossification (HO) following total hip arthroplasty (THA) and if ASA dosage impacted the rate of HO.

METHODS

Eligible studies published from January 2000 to July 2022 were identified from the computerized searching of PubMed, Scopus and Web of Science. HO was defined according to Brooker Classification. Pooled risk ratios (OR) and 95% confidence interval (CI) were estimated under a random-effect model. Additionally, combined HO incidences were compared according to ASA dosage (a regular dose of 325 bid vs. a low dose of 81 mg bid/162 mg qd).

RESULTS

Thirteen studies were included. ASA administered for VTE prophylaxis was significantly associated with a reduced risk of all-grade HO following THA (univariate, OR: 0.50, 95% CI: 0.34-0.74, P < 0.001; multivariate, OR: 0.60, 95% CI: 0.49-0.73, P < 0.001). Similar results could be observed for high-grade HO (univariate, OR: 0.57, 95% CI: 0.36-0.89, P = 0.015; multivariate, OR: 0.50, 95% CI: 0.27-0.92, P = 0.026). There was a non-significant trend towards a higher incidence of HO formation for low-dose ASA (31%, 95% CI: 29-34%), compared with regular-dose ASA (21%, 95% CI: 11-33%) (P = 0.069 under test of interaction).

CONCLUSIONS

ASA can be an effective option for HO prophylaxis. More well-designed trials with long-term follow-ups are encouraged to confirm the current findings and to investigate the effect of ASA dosage on HO reduction.

Aspirin as a thromboprophylaxis agent after revision knee arthroplasty: A retrospective analysis

Introduction

Total knee arthroplasty is a common and effective procedure. Although complication rates are low, certain complications such as venous thromboembolism are potentially serious. The optimal prophylactic agent and dosage after revision knee arthroplasty remains unclear. The main objective of this work was to study the efficacy and safety of aspirin as a thromboprophylaxis agent following revision knee arthroplasties.

Patients and methods

A retrospective review of patients undergoing revision knee arthroplasty between 2013 and 2020at a University Teaching Hospital was undertaken. The primary outcome was the development of a symptomatic thromboembolic event requiring treatment within 90 days post-surgery. The secondary outcomes were adverse events associated with aspirin therapy: surgical site infection rate; incidence of major bleeding; readmission rate and mortality within 90 days post-surgery.

Results

490 patients were included. 374 (76.3%) received prophylactic aspirin (150 mg once daily for 28 days) and 75 (15.3%) patients received dalteparin for 28 days due to contraindication to aspirin use. Those already receiving other thromboprophylaxis agents for pre-existing comorbidities continued these after relevant medical consultation. The overall rates of venous thromboembolism and symptomatic DVT after aspirin prophylaxis were 0.6% (3/490) and 0.8% (3/374), respectively. VTE incidence did not significantly differ between those administered aspirin and other agents. No patient experienced major bleeding within 90 postoperative days. Only 2 of 490 (0.4%) patients had wound infection requiring readmission; neither received prophylactic aspirin.

Conclusion

Extended out-of-hospital thromboembolic prophylaxis with aspirin may be at least as effective as other agents in patients undergoing revision knee arthroplasty. Aspirin is safe, effective, and cheap compared with other agents.

Thirty day low-dose versus regular-dose aspirin for venous thromboembolism prophylaxis in primary total joint arthroplasty

BACKGROUND

The optimal dosing of aspirin (ASA) monotherapy for prophylaxis after total joint arthroplasty is debatable. The objective of this study was to compare two ASA regimens with regards to symptomatic deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding, and infection 90 days after primary total hip arthroplasty (THA) and total knee arthroplasty (TKA).

METHODS

We retrospectively identified 625 primary THA and TKA surgeries in 483 patients who received ASA for 4 weeks post-op. 301 patients received 325 mg once daily (QD) and 324 patients received 81 mg twice daily (BID). Patients were excluded if they were minors, had a prior venous thromboembolism (VTE), had ASA allergy, or received other VTE prophylaxis drugs.

RESULTS

There was a significant difference in rate of bleeding and suture reactions between the two groups. Bleeding was 7.6% for 325 mg QD and 2.5% for 81 mg BID (p = .0029 Χ2, p = .004 on multivariate logistic regression analysis). Suture reactions were 3.3% for 325 mg QD and 1.2% for 81 mg BID (p = .010 Χ2, p = .027 on multivariate logistic regression analysis). Rates of VTE, symptomatic DVT, and PE were not significantly different. The incidence of VTE was 2.7% for 325 mg QD and 1.5% for 81 mg BID (p = .4056). Symptomatic DVT rates were 1.6% for 325 mg QD and 0.9% for 81 mg BID (p = .4139). Deep infection was 1.0% for 325 mg QD and 0.31% for 81 mg BID (p = .3564).

CONCLUSION

Low-dose ASA in patients with limited comorbidities undergoing primary THA and TKA is associated with significant lower rates of bleeding and suture reactions than high dose ASA. Low-dose ASA was not inferior to higher dose ASA for the prevention of VTE, wound complications, and infection 90 days postoperatively.

Role of non-ASA VTE prophylaxis in risk for manipulation following primary total knee arthroplasty

INTRODUCTION

Stiffness and decreased range of motion frequently lead to hindrance of activities of daily living and dissatisfaction follow total knee arthroplasty (TKA). This study aims to evaluate the effect of non-aspirin (ASA) chemoprophylaxis and determine patient-related risk factors for stiffness and need for manipulation under anesthesia (MUA) following primary TKA.

MATERIALS AND METHODS

A review of all patients undergoing primary TKA from 2013 to 2019 at a single academic orthopedic hospital was conducted. The primary outcome measure was MUA performed post-operatively. Chi-square analysis and Mann-Whitney U test were used to determine statistically significant relationships between risk factors and outcomes. Significance was set at p < 0.05. Univariate logistic regression was performed to control for identified independent risk factors for MUA.

RESULTS

A total of 11,550 patients undergoing primary TKA from January 2013 to September 2019 at an academic medical center were included in the study. Increasing age and Charlson Comorbidity Index were associated with statistically significant decreased odds of MUA (0.93, 95% CI: 0.92-0.94, p < 0.001, OR 0.71, 95% CI 0.63-0.79, p < 0.001). Active smokers had a 2.01 increased odds of MUA (OR 2.01, 95% CI 1.28, 3.02, p < 0.001). There was no significant difference in rates of MUA between ASA and non-ASA VTE prophylaxis (p 0.108).

CONCLUSIONS

Younger age, lower CCI, and history of smoking are associated with a higher rate, while different chemical VTE prophylaxis does not influence rate of MUA after TKA. Arthroplasty surgeons should consider these risk factors when counseling patient preoperatively. Understanding each patients' risk for MUA allows surgeons to appropriately set preoperative expectations and reasonable outcome goals.

Trends of Venous Thromboembolism After Total Hip Arthroplasty in the United States: Analysis From 2011 to 2019

BACKGROUND

In 2011, the American Academy of Orthopaedic Surgeons released a Clinical Practice Guideline` that recommended routine venous thromboembolism (VTE) prophylaxis after total joint arthroplasty. The purpose of this study was to examine (1) the change in the incidence of 90-day VTE, deep vein thrombosis, and pulmonary embolism, (2) the change in the utilization of antithrombotic agents; and (3) the change in the economic burden associated with VTE after total hip arthroplasty (THA) from 2011 to 2019.

METHODS

National, administrative claims data from 2011 to 2019 were used to identify patients who underwent primary THA for osteoarthritis. Exclusions entailed liver pathology, coagulopathy, malignancy, or those on prior prescribed blood thinners before THA. Multivariable regression was used, controlling for age and Charlson Comorbidity Index for all years, with 2011 as the reference year.

RESULTS

From 2011 to 2019, there was a significant reduction in 90-day VTE rates after THA, with a significant reduction in deep vein thrombosis and pulmonary embolism during this time frame as well. Of the antithrombotic agents prescribed after THA, the utilization of prescribed aspirin significantly increased and that of nonaspirin anticoagulants significantly decreased. Among nonaspirin anticoagulants, the utilization of direct factor Xa inhibitors and direct thrombin inhibitors significantly increased. The added reimbursements associated with VTE after THA significantly decreased during this period.

CONCLUSION

Since 2011, the incidence and economic burden associated with VTE after THA have significantly declined. In addition, there has been an increase in prescription aspirin and direct oral anticoagulants.

LEVEL OF EVIDENCE

Therapeutic, III.

Trends in Venous Thromboembolism After Shoulder Arthroplasty in the United States: Analysis Following the 2009 American Academy of Orthopaedic Surgeons Clinical Practical Guidelines

BACKGROUND

In 2009, the American Academy of Orthopaedic Surgeons released a consensus recommending venous thromboembolism (VTE) prophylaxis after total shoulder arthroplasty (TSA). The purpose of this study was to examine the (1) change in incidence of 90-day VTE, deep vein thrombosis (DVT), and pulmonary embolism; (2) change in utilization of chemoprophylaxis; and (3) change in the economic burden associated with VTE after TSA from 2010 to 2019.

METHODS

Using the PearlDiver database, national data from 2010 to 2019 were used to identify patients who underwent primary TSA for osteoarthritis and/or rotator cuff arthropathy. Exclusions entailed liver pathology, coagulopathy, or those on prior prescribed blood thinners before TSA. Multivariable regression was used controlling for age and Charlson Comorbidity Index for all years with 2010 as the reference year.

RESULTS

From 2010 to 2019, there was a reduction in VTE rates from 0.89% in 2010 to 0.78% in 2019. Regarding implant type, there was no notable change in incidence of VTE, DVT, and pulmonary embolism within 90 days after anatomic TSA. Notable reductions were observed in both VTE and DVT after reverse TSA from 2010 to 2019. Prescribed chemical VTE prophylaxis utilization after TSA markedly increased from 4.41% in 2010 to 11.70% utilization in 2019. The utilization of aspirin markedly increased from 17.27% in 2010 to 65.17% in 2019. Among anticoagulants, the utilization of direct factor Xa inhibitors increased from 0.0% utilization in 2010 to 66.09% utilization in 2019. The added reimbursements associated with VTE after TSA markedly decreased from $14,122 in 2010 to $4,348 in 2019.

CONCLUSION

The incidence and economic burden associated with VTE after TSA have markedly declined following the 2010 American Academy of Orthopaedic Surgeons clinical practice guidelines. This reduction can be attributed to both an increase in VTE prevention through increased utilization of prescribed chemoprophylaxis and improvement in VTE treatment strategies.

LEVEL OF EVIDENCE

Therapeutic, III.

Aspirin for Venous Thromboembolic Prophylaxis Following Total Hip and Total Knee Arthroplasty: An Analysis of Safety and Efficacy Accounting for Surgeon Selection Bias

BACKGROUND

Aspirin may be effective at preventing venous thromboembolism following total knee arthroplasty (TKA) or total hip arthroplasty (THA). Current evidence is limited by bias as many surgeons who use aspirin prescribe for high-risk patients alternative chemoprophylactic agents. Therefore, this study aimed to evaluate the risk of pulmonary embolism (PE) and deep vein thrombosis (DVT) in patients who received aspirin and warfarin while accounting for surgeon selection bias.

METHODS

A national database was queried for patients undergoing primary elective TKA or THA from 2015 to 2020. Patients whose surgeon used aspirin in >90% of their patients were compared to patients whose surgeon used warfarin in >90% of cases. Instrumental variable analyses were performed to assess for PE, DVT, and transfusion while accounting for selection bias. Among TKA patients, 26,657 (18.8%) were in the warfarin cohort and 115,005 (81.2%) were in the aspirin cohort. Among THA patients, 13,035 (17.7%) were in the warfarin cohort and 60,726 (82.3%) were in the aspirin cohort.

RESULTS

Analyses were unable to identify a difference in the risk of PE (TKA: adjusted odds ratio [aOR]: 0.98, P = .659; THA: aOR = 0.93, P = .310) and DVT (TKA: aOR = 1.05, P = .188; THA: aOR = 0.96, P = .493) between the aspirin and warfarin cohorts. However, the aspirin cohort was associated with a lower risk of transfusion (TKA: aOR = 0.58, P < .001, THA: 0.84, P < .001).

DISCUSSION

After accounting for surgeon selection bias, aspirin was as effective as warfarin at preventing PE and DVT following TKA and THA. Furthermore, aspirin was associated with a lower risk of transfusion compared to warfarin.

Aspirin thromboprophylaxis following primary total knee arthroplasty is associated with a lower rate of early prosthetic joint infection compared with other agents

BACKGROUND

Patients undergoing total knee arthroplasty (TKA) are at increased risk of venous thromboembolism (VTE). Aspirin has been shown to be effective at reducing rates of VTE. In select patients, more potent thromboprophylaxis is indicated, which has been associated with increased rates of bleeding and wound complications. This study aimed to evaluate the effect of thromboprophylaxis choice on rates of early prosthetic joint infection (PJI) following TKA.

METHODS

A review of 11,547 primary TKA patients from 2013 to 2019 at a single academic orthopaedic hospital was conducted. The primary outcome measure was PJI within 90 days of surgery as measured by Musculoskeletal Infection Society criteria. There were 59 (0.5%) patients diagnosed with early PJI. Chi-square and Welch-Two Sample t-tests were used to determine statistically significant relationships between thromboprophylaxis and demographic variables. Significance was set at p<0.05. Multivariate logistic regression adjusted for age, body mass index, sex, and Charlson comorbidity index was performed to identify and control for independent risk factors for early PJI.

RESULTS

There was a statistically significant difference in the rates of early PJI between the aspirin and non-aspirin group (0.3 vs 0.8%, p<0.001). Multivariate logistic regressions revealed that patients given aspirin thromboprophylaxis had significantly lower odds of PJI (odds ratios (OR)=0.51, 95% Confidence Interval (CI) 0.29 to 0.89, p=0.019) compared to non-aspirin patients.

CONCLUSIONS

The use of aspirin thromboprophylaxis following primary TKA is independently associated with a lower rate of early PJIs. Arthroplasty surgeons should consider aspirin as the gold standard thromboprophylaxis in all patients in which it is deemed medically appropriate and should carefully weigh the morbidity of PJI in patients when non-aspirin thromboprophylaxis is considered.

Discontinued Use of Outpatient Portable Intermittent Pneumatic Compression Devices May Be Safe for Venous Thromboembolism Prophylaxis in Primary Total Knee Arthroplasty Using Low-Dose Aspirin

Venous thromboembolism (VTE) is a rare, but serious complication following total knee arthroplasty (TKA). Current VTE guidelines recommend pharmacologic agents with or without intermittent pneumatic compression devices (IPCDs). At our institution, both 81-mg aspirin (ASA) twice a day (BID) and portable IPCDs were previously prescribed to TKA patients at standard risk for VTE, but the IPCDs were discontinued and patients were treated with ASA alone going forward. The aim of this study is to determine if discontinued use of outpatient IPCDs is safe and does not increase the rate of VTE or any other related complications in patients following TKA. A retrospective review of 2,219 consecutive TKA cases was conducted, identifying patients with VTE, bleeding complications, infection, and mortality within 90 days postoperatively. Patients were divided into two cohorts. Patients in cohort one received outpatient IPCDs for a period of 14 days (control), while those in cohort two did not (ASA alone). All study patients received inpatient IPCDs and were maintained on 81-mg ASA BID for 28 days. A posthoc power analysis was performed using a noninferiority margin of 0.25 (α = 0.05; power = 80%), which showed that our sample size was fully powered for noninferiority for our reported deep vein thrombosis (DVT) rates, but not for pulmonary embolism (PE) rates. A total of 867 controls and 1,352 patients treated with ASA alone were identified. Only two control patients were diagnosed with a PE (0.23%), while one patient in the ASA alone group had DVT (0.07%). There was no statistical difference between these rates (p = 0.33). Furthermore, no differences were found in bleeding complications (p = 0.12), infection (p = 0.97), or 90-day mortality rates (p = 0.42) between both groups. The discontinued use of outpatient portable IPCDs is noninferior to outpatient IPCD use for DVT prophylaxis. Our findings suggest that this protocol change may be safe and does not increase the rate of VTE in standard risk patients undergoing TKA while using 81-mg ASA BID.

The impact of surgical trainee involvement in total hip arthroplasty: a systematic review of surgical efficacy, patient safety, and outcomes

PURPOSE

Concerns persist that trainee participation in surgical procedures may compromise patient care and potentiate adverse events and costs. We aimed to analyse the potential impact and consequences of surgical trainee involvement in total hip arthroplasty (THA) procedures in terms of surgical efficacy, patient safety, and functional outcomes.

METHODS

We systematically reviewed Medline/PubMed, EMBASE, the Cochrane library, and Scopus databases in October 2021. Eligible studies reported a direct comparison between THA cases performed with and without trainee involvement.

RESULTS

Eighteen publications met our eligibility criteria and were included in our study. The included studies reported on 142,450 THAs completed on 142,417 patients. Specifically, 48,155 and 94,295 surgeries were completed with and without trainee involvement, respectively. The mean operative times for procedures with (n = 5,662) and without (n = 14,763) trainee involvement were 106.20 and 91.41 min, respectively. Mean overall complication rates were 6.43% and 5.93% for THAs performed with (n = 4842) and without (n = 12,731) trainees. Lastly, the mean Harris Hip Scores (HHS) for THAs performed with (n = 442) and without (n = 750) trainee participation were 89.61 and 86.97, respectively.

CONCLUSION

Our systematic review confirmed previous studies' reports of increased operative time for THA cases with trainee involvement. However, based on the overall similar complication rates and functional hip scores obtained, patients should be reassured concerning the relative safety of trainee involvement in THA. Future prospective studies with higher levels of evidence are still needed to reinforce the existing evidence.

Time to Venous Thromboembolism Events Following Total Hip Arthroplasty: A Comparison Between Aspirin and Warfarin

BACKGROUND

The attitude and approach of orthopedic community for minimizing venous thromboembolism (VTE) has evolved over the last decade with the trend toward use of aspirin (and mechanical modalities) in lieu of aggressive anticoagulation. The optimal length of VTE prophylaxis following total hip arthroplasty (THA) still remains unknown. This study aimed to determine the timing of VTE in patients who received aspirin compared to warfarin, and determine if 30 days of prophylaxis remain adequate.

METHODS

This is a retrospective study of 18,003 patients undergoing primary and revision THA at a single institution between January 2008 and August 2020. During this time, our institution underwent a transition from the use of warfarin to aspirin as the main method for VTE prophylaxis. Symptomatic deep vein thrombosis and pulmonary embolism occurring within 90 days of surgery were identified from medical records and phone call logs. Aspirin and warfarin cohorts were matched to account for demographic and comorbidity differences. Timing of pulmonary embolism was determined based on either the date of diagnostic imaging or patient-provider phone calls confirming diagnosis.

RESULTS

The cohorts included 46 patients in the warfarin group and 46 in the aspirin group. Time to VTE was significantly shorter in the warfarin group compared to aspirin (P = .021) with a median time to VTE of 3 days (interquartile range 2-14) and 10 days (interquartile range 4-19) respectively. Over 90% of the events occurred within 32 or 30 days of surgery in the warfarin and aspirin groups respectively.

CONCLUSION

Based on the findings, a 30-day aspirin prophylaxis remains appropriate for patients undergoing THA.

Aspirin monotherapy is a suitable standard thromboprophylactic agent following total hip arthroplasty

INTRODUCTION

Aspirin is increasingly recognised as an efficacious thromboprophylactic agent with a superior safety profile compared to alternatives. Following our institution's previously published experience we implemented a risk-stratified protocol utilising aspirin as standard. We now present retrospective review of standard use of aspirin on fatal pulmonary embolism, all-cause mortality, and venous thromboembolism (VTE) following total hip arthroplasty (THA).

METHODS

A consecutive series of elective THAs was identified. Prospectively maintained databases were analysed to yield demographic data and identify deaths or readmission data. Patients who died within 90 postoperative days underwent review of the complete medical record.

RESULTS

4204 THAs were included in the study cohort. VTE prophylaxis prescription was available in 3805. 2560 received aspirin (67.3%), 1049 enoxaparin (27.6%) and 193 warfarin (5.1%); there were no differences in 90-day all-cause mortality (p = 0.780) or VTE (p = 1) between groups.

CONCLUSION

Our large series continues to demonstrate that aspirin for thromboprophylaxis following THA is effective in risk-stratified patients. Furthermore, we demonstrate that introduction of a departmental protocol establishing aspirin as standard practice was not associated with increased mortality or incidence of thromboembolism. Taken in conjunction with our previous cohort our series encompasses 11,420 consecutive THAs. There has been a single death following fatal PE in the aspirin group (0.02%) compared to 5 in the LMWH group (0.2%) and 1 in the warfarin group (0.06%). We join calls for large-scale randomised controlled trials to elucidate the place of aspirin in VTE prevention following hip arthroplasty.

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.

Low-Dose Aspirin is Safe and Effective for Venous Thromboembolism Prevention in Patients Undergoing Revision Total Knee Arthroplasty: A Retrospective Cohort Study

Venous thromboembolism (VTE) events are rare, but serious complications of total joint replacement affect patients and health care systems due to the morbidity, mortality, and associated cost of its complications. There is currently no established universal standard of care for prophylaxis against VTE in patients undergoing revision total knee arthroplasty (rTKA). The aim of this study was to determine whether a protocol of 81-mg aspirin (ASA) bis in die (BID) is safe and/or sufficient in preventing VTE in patients undergoing rTKAs versus 325-mg ASA BID. In 2017, our institution adopted a new protocol for VTE prophylaxis for arthroplasty patients. Patients initially received 325-mg ASA BID for 1 month and then changed to a lower dose of 81-mg BID. A retrospective review from 2011 to 2019 was conducted identifying 1,438 consecutive rTKA patients and 90-day postoperative outcomes including VTE, gastrointestinal, and wound bleeding complications, acute periprosthetic joint infection, and mortality. In the 74 months prior to protocol implementation, 1,003 rTKAs were performed and nine VTE cases were diagnosed (0.90%). After 26 months of the protocol change, 435 rTKAs were performed with one VTE case identified (0.23%). There was no significant difference in rates or odds in postoperative pulmonary embolism (PE; p = 0.27), DVT (p = 0.35), and total VTE rates (p = 0.16) among patients using either protocol. There were also no differences in bleeding complications (p = 0.15) or infection rate (p = 0.36). No mortalities were observed. In the conclusion, 81-mg ASA BID is noninferior to 325-mg ASA BID in maintaining low rates of VTE and may be safe for use in patients undergoing rTKA.

Addressing the Needs of the Rapidly Aging Society through the Development of Multifunctional Bioactive Coatings for Orthopedic Applications

The unprecedented aging of the world's population will boost the need for orthopedic implants and expose their current limitations to a greater extent due to the medical complexity of elderly patients and longer indwelling times of the implanted materials. Biocompatible metals with multifunctional bioactive coatings promise to provide the means for the controlled and tailorable release of different medications for patient-specific treatment while prolonging the material's lifespan and thus improving the surgical outcome. The objective of this work is to provide a review of several groups of biocompatible materials that might be utilized as constituents for the development of multifunctional bioactive coatings on metal materials with a focus on antimicrobial, pain-relieving, and anticoagulant properties. Moreover, the review presents a summary of medications used in clinical settings, the disadvantages of the commercially available products, and insight into the latest development strategies. For a more successful translation of such research into clinical practice, extensive knowledge of the chemical interactions between the components and a detailed understanding of the properties and mechanisms of biological matter are required. Moreover, the cost-efficiency of the surface treatment should be considered in the development process.

Enhanced Recovery after Surgery for Knee Arthroplasty in the Era of COVID-19

Enhanced recovery after surgery (ERAS) represents a paradigm shift in perioperative care, aimed at achieving early recovery for surgical patients, reducing length of hospital stay, and complications. The purpose of this study was to provide an insight of the impact of the COVID-19 on ERAS protocols for knee arthroplasty patients in a tertiary hospital and potential strategy changes for postpandemic practice. We retrospectively reviewed all cases that underwent surgery utilizing ERAS protocols in the quarter prior to the pandemic (fourth quarter of 2019) and during the first quarter of 2020 when the pandemic started. A review of the literature on ERAS protocols for knee arthroplasty during the COVID-19 pandemic was also performed and discussed. A total of 199 knee arthroplasties were performed in fourth quarter of 2019 as compared with 76 in the first quarter of 2020 during the COVID-19 outbreak. Patients who underwent surgery in the first quarter of 2020 had shorter inpatient stays (3.8 vs. 4.5 days), larger percentage of discharges by postoperative day 5 (86.8 vs. 74.9%), and a larger proportion of patients discharged to their own homes (68 vs. 54%). The overall complication rate (1.3 vs. 3%) and readmission within 30 days (2.6 vs. 2%) was similar between both groups. ERAS protocols appear to reduce hospital lengths of stay for patients undergoing knee arthroplasty without increasing the risk of short-term complications and readmissions. The beneficial effects of ERAS appear to be amplified by and are synchronous with the requirements of operating in the era of a pandemic.

Multiple Venous Thromboembolism Pharmacologic Agents Are Associated with an Increased Risk for Early Postoperative Complications following a Total Joint Arthroplasty

The purpose of this study was to determine the effect that concurrent venous thromboembolism (VTE) medications had on early outcomes following primary total joint arthroplasty (TJA). 2653 total knee and hip arthroplasties were reviewed at a tertiary medical center. The study performed a multivariable comparison of outcomes in patients on 2 or more VTE medications, as well as a logistic regression on outcomes following each addition of a VTE medication postoperatively (number of VTE medications was 1–4). Controlling for gender, age, body mass index, and preoperative American Society of Anesthesiologists score throughout the analysis, patients who received 2 or more VTE prophylaxis medications had increased LOS (p < 0.001), transfusions (p < 0.001), emergency department visits (p=0.001), readmissions (p < 0.001), 90dPOE (p < 0.001), and PE (p < 0.001). Every additional postoperative VTE medication incrementally increased the risk for longer LOS (p < 0.001), transfusions (p < 0.001), 90dPOE (p < 0.001), deep vein thrombosis (p=0.049), PE (p < 0.001), emergency department visits (p=0.005), and readmission (p=0.010). Patients on multiple VTE medications following TJA demonstrate significantly poorer outcomes. The current study's findings caution the use of multiple VTE medications whenever possible immediately following a TJA.

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.

Predictors and Outcomes of Postoperative Hemoglobin of <8 g/dL in Total Joint Arthroplasty

BACKGROUND

Restrictive transfusion practices have decreased transfusions in total joint arthroplasty (TJA). A hemoglobin threshold of <8 g/dL is commonly used. Predictors of this degree of postoperative anemia in TJA and its association with postoperative outcomes, independent of transfusions, remain unclear. We identified predictors of postoperative hemoglobin of <8 g/dL and outcomes with and without transfusion in TJA.

METHODS

Primary elective TJA cases performed with a multimodal blood management protocol from 2017 to 2018 were reviewed, identifying 1,583 cases. Preoperative and postoperative variables were compared between patients with postoperative hemoglobin of <8 and ≥8 g/dL. Logistic regression and receiver operating characteristic curves were used to assess predictors of postoperative hemoglobin of <8 g/dL.

RESULTS

Positive predictors of postoperative hemoglobin of <8 g/dL were preoperative hemoglobin level (odds ratio [OR] per 1.0-g/dL decrease, 3.0 [95% confidence interval (CI), 2.4 to 3.7]), total hip arthroplasty (OR compared with total knee arthroplasty, 2.1 [95% CI, 1.3 to 3.4]), and operative time (OR per 30-minute increase, 2.0 [95% CI, 1.6 to 2.6]). Negative predictors of postoperative hemoglobin of <8 g/dL were tranexamic acid use (OR, 0.42 [95% CI, 0.20 to 0.85]) and body mass index (OR per 1 kg/m2 above normal, 0.90 [95% CI, 0.86 to 0.94]). Preoperative hemoglobin levels of <12.4 g/dL in women and <13.4 g/dL in men best predicted postoperative hemoglobin of <8 g/dL. Overall, 5.2% of patients with postoperative hemoglobin of 7 to 8 g/dL and 95% of patients with postoperative hemoglobin of <7 g/dL received transfusions. Patients with postoperative hemoglobin of <8 g/dL had longer hospital stays (p < 0.001) and greater rates of emergency department visits or readmissions (p = 0.001) and acute kidney injury (p < 0.001). Among patients with postoperative hemoglobin of <8 g/dL, patients who received transfusions had a lower postoperative hemoglobin nadir (p < 0.001) and a longer hospital stay (p = 0.035) than patients who did not receive transfusions.

CONCLUSIONS

Postoperative hemoglobin of <8 g/dL after TJA was associated with worse outcomes, even for patients who do not receive transfusions. Optimizing preoperative hemoglobin levels may mitigate postoperative anemia and adverse outcomes.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Patients Who Do Not Receive Aspirin Because of Allergy Have an Increased Risk of Venous Thromboembolism Following Total Joint Arthroplasty

BACKGROUND

Patient-reported allergies to aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) may preclude certain patients from receiving aspirin as venous thromboembolism (VTE) prophylaxis after total joint arthroplasty (TJA). The purpose of the study was to (1) determine whether the use of non-aspirin agents due to a self-reported aspirin or NSAID allergy was associated with a higher incidence of VTE and (2) determine the rate of true allergic reactions in patients who reported an allergy but still received aspirin.

METHODS

Prospectively collected data from 45,171 patients who underwent primary TJA between 2000 and 2019 were reviewed. Patients who reported an allergy to aspirin or NSAIDs were identified (n = 823). Using a validated VTE risk calculator, each patient was assigned a risk score based on 26 comorbidities. Bleeding complications, VTEs that occurred within 90 days postoperatively, and allergic reactions were collected as end points. Multivariable logistic regression was performed to determine the factors associated with VTE.

RESULTS

The overall incidence of aspirin or NSAID allergy was 1.8%. Only 80 of 267 patients (30%) reported an allergy to only aspirin and still received aspirin. Compared with patients who received aspirin without a history of allergy (n = 17,648), patients who received non-aspirin thromboprophylaxis due to allergy (n = 383) had a higher incidence of VTE (2.87% versus 0.24%, p < 0.001). On multivariable regression, these patients had an 8-fold increase in VTE risk (adjusted odds ratio, 7.94; 95% confidence interval, 2.86 to 22.07; p < 0.001). The incidence of true allergic reactions to aspirin among those with a reported allergy was 1.8% (number needed to harm = 55). No patients developed anaphylaxis or severe hypersensitivity reactions.

CONCLUSIONS

Patients with a self-reported allergy to aspirin or NSAIDs were at a significantly increased risk for VTE if they received non-aspirin thromboprophylaxis agents following TJA. Future research should evaluate the usefulness of preoperative allergy testing when selecting a VTE prophylactic agent in patients with self-reported allergies.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Aspirin thromboprophylaxis in joint replacement surgery

BACKGROUND

Aspirin is commonly used as the only pharmacologic agent for prevention of venous thromboembolism (VTE) after joint replacement surgery in the United States. Despite this, prospective studies investigating VTE events after aspirin-only thromboprophylaxis in joint replacement surgery are lacking in the real-world setting.

OBJECTIVES

The aim of this study was to estimate the risk of VTE with aspirin-only pharmacologic prophylaxis following joint replacement surgery.

METHODS

We carried out a prospective observational study of 350 low-risk patients (no prior history of VTE and low cardiovascular risk factors) who underwent total knee and total hip arthroplasty and received only aspirin for thromboprophylaxis postoperatively.

RESULTS

The observed risk of symptomatic VTE was 1.7% (95% confidence interval, 0.9%-3.3%) over 3 months of follow up, with only one major bleeding event and no surgical hematomas.

CONCLUSION

The risk of VTE with aspirin monotherapy for thromboprophylaxis in joint replacement surgery in this real-world cohort was higher than previously reported.

Weight-Based Aspirin Dosing May Further Reduce the Incidence of Venous Thromboembolism Following Primary Total Joint Arthroplasty

BACKGROUND

Obesity poses a challenge to thromboembolic prophylaxis following total joint arthroplasty (TJA). The purpose of this study is to evaluate a weight-based aspirin dosing regimen for prevention of venous thromboembolism (VTE) following TJA.

METHODS

This is a retrospective observational study of 2403 patients who underwent primary total hip or knee arthroplasty at one institution. A weight-based aspirin dosing regimen for VTE prophylaxis was administered to 1247 patients: patients weighing ≥120 kg received 325 mg aspirin twice daily (BID) and those weighing <120 kg received 81 mg aspirin BID for 4 weeks. In total, 1156 patients in the comparison cohort received 81 mg aspirin BID. VTE and gastrointestinal bleeding events were identified through chart review at 42 days and 6 months postoperatively. A multivariable logistic regression was performed to adjust for covariates.

RESULTS

The weight-based aspirin cohort had a significantly lesser incidence of VTE at 42 days (P = .03, relative risk [RR] 0.31, 95% confidence interval 0.12-0.82) and 6 months (P = .03, RR 0.38, 95% confidence interval 0.18-0.80). There was no difference in VTE incidence between total hip arthroplasty and total knee arthroplasty cases (P = .8). There was no difference in gastrointestinal bleeding events between the cohorts at 42 days (P = .69) or 6 months (P = .92). Subanalysis of patients weighing ≥120 kg demonstrated a significant difference between the cohorts with a VTE incidence of 3.48% and 0% in the 81 mg and weight-based cohorts, respectively (P = .02).

CONCLUSION

Patients prescribed a weight-based aspirin regimen had significantly fewer VTEs after TJA compared to historical controls with an RR reduction of 69% at 6 weeks and 62% at 6 months postoperatively. This suggests the need to factor patient weight when determining postoperative VTE prophylaxis with aspirin.

Prevention of venous thromboembolism with aspirin following knee surgery: A systematic review and meta-analysis

Venous thromboembolism (VTE) is a well-known complication following orthopaedic surgery. The incidence of this complication has decreased substantially since the introduction of routine thromboprophylaxis. However, concerns have been raised about increased bleeding complications caused by aggressive thromboprophylaxis.Attention has grown for aspirin as a safer thromboprophylactic agent following orthopaedic surgery.A systematic review using MEDLINE, Embase and Web of Science databases was undertaken to compare the effectiveness of aspirin prophylaxis following knee surgery with the current standard prophylactic agents (low molecular weight heparin [LMWH], vitamin K antagonists and factor Xa inhibitors).No significant difference in effectiveness of VTE prevention was found between aspirin, LMWH and warfarin. Factor Xa inhibitors were more effective, but increased bleeding complications were reported.As evidence is limited and of low quality with substantial heterogeneity, further research with high-quality, adequately powered trials is needed. Cite this article: EFORT Open Rev 2021;6:892-904. DOI: 10.1302/2058-5241.6.200120.

Thirty Days of Aspirin for Venous Thromboembolism Prophylaxis Is Adequate Following Total Knee Arthroplasty, Regardless of the Dose Used

BACKGROUND

The optimal length of aspirin prophylaxis to minimize venous thromboembolism (VTE) following total knee arthroplasty (TKA) remains unknown. This study aimed to determine the timing of VTE after TKA in patients who received low and high dose aspirin, and determine if 30 days of prophylaxis remains adequate.

METHODS

We retrospectively reviewed records of 9208 patients undergoing primary TKA between 2010 and 2020 who received either low (81 mg twice daily, n = 4413) or high (325 mg twice daily, n = 4795) dose aspirin for VTE prophylaxis. Symptomatic VTEs occurring within 90 days of surgery were identified from medical records and phone call logs. Major bleeding events (MBE) within the first 30 days were also documented. Time to event was recorded.

RESULTS

Overall, 88 patients (1.0%) developed symptomatic VTE, with no significant differences in incidence between the low (n = 40, 0.9%) and high (n = 48, 1.0%) dose groups (P = .669). The median time to VTE was 8 days (interquartile range [IQR] 2-15.5), median time to deep vein thrombosis was 12 days (IQR 5-18), and median time to pulmonary embolism was 5 days (IQR 1.5-15). There was a similar distribution in time to VTE in both the low and high dose groups. Aside from a single DVT occurring at day 44, all VTE occurred within 30 days of surgery. During the prophylactic time period, 41 patients (0.4%) developed MBE, which tended to occur more frequently (0.6% vs 0.3%, P = .018) and earlier in the high dose group.

CONCLUSION

Based on the findings, a 30-day low or high dose aspirin regimen remains optimal for prevention of VTE without increasing MBE in TKA patients.

Time for an Update? A Look at Current Guidelines for Venous Thromboembolism Prophylaxis After Hip and Knee Arthroplasty and Hip Fracture

Venous thromboembolism is a well-established complication of total hip and knee arthroplasty and hip fracture surgery. Clinical practice guidelines have been proposed to help clinicians provide prophylaxis against this risk. However, most guidelines reference data that are becoming outdated because of new advances in perioperative protocols. Recent data would suggest that aspirin may be appropriate for most patients after total hip and knee replacement and a more potent chemoprophylaxis for higher risk patients. Low-molecular-weight heparin remains the recommended choice after hip fracture surgery, although there is a paucity of recent literature in this patient population. There are randomized trials currently underway in the arthroplasty population that may guide clinicians in the appropriate choice of chemoprophylaxis. These studies should inform updates to the current clinical practice guidelines.

Periprosthetic Joint Infection Is Associated with an Increased Risk of Venous Thromboembolism Following Revision Total Knee Replacement: An Analysis of Administrative Discharge Data

BACKGROUND

Little is known about the relationship between infection and the risk of risk of venous thromboembolism (VTE) following orthopaedic surgery. We assessed the 90-day risk of VTE following revision total knee replacement to measure the association between periprosthetic joint infection and the risk of postoperative VTE.

METHODS

We used New York Statewide Planning and Research Cooperative System data to identify all New York State residents undergoing revision total knee replacement from 1998 to 2014. ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification) codes were used to identify comorbidities and to classify the indication for revision total knee replacement as aseptic, infection, or fracture. The primary outcome was any diagnosis code for VTE recorded for the revision surgery and/or subsequent admissions within 90 days. A multivariable logistic regression model that included demographic characteristics and comorbidities was used to estimate the risk of VTE after revision for infection or fracture, with aseptic revision as the reference group.

RESULTS

The present study included 25,441 patients who were managed with revision total knee replacement; the indication for revision was aseptic for 17,563 patients (69%), infection for 7,075 (28%), and fracture for 803 (3%). The mean age (and standard deviation) was 66 ± 12 years, 15,592 (61%) of the patients were female, 3,198 (13%) were Black, 1,192 (5%) were smokers, and 4,222 (17%) were obese. Seven hundred and nineteen patients (2.8%) had VTE within the 90 days after revision total knee replacement, including 387 (1.5%) during the admission for the revision procedure. The 90-day incidence of VTE was 2.1% after aseptic revision, 4.3% after revision for infection, and 5.9% after revision for fracture. The adjusted odds ratio (aOR) for VTE relative to aseptic revision was 2.01 (95% confidence interval [CI], 1.72 to 2.35) for septic revision total knee replacement and 2.62 (95% CI, 1.91 to 3.6) for fracture. A history of VTE was also a strong risk factor for VTE following revision total knee replacement (aOR, 2.01; 95% CI, 1.48 to 2.71).

CONCLUSIONS

We found that the odds of VTE after revision total knee replacement for infection were double those after aseptic revision total knee replacement. Although fracture accounts for a small percentage of revision total knee replacements, the risk of VTE was 2.6-fold higher after these procedures. The indication for revision total knee replacement should be considered when choosing postoperative VTE prophylaxis.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Chronic Application of Low-Dose Aspirin Affects Multiple Parameters of Three Blood Cellular Types and Antithrombin Activity: A 1:1:1 Propensity Score Matching Analysis

ABSTRACT

The mechanisms of aspirin antithrombotic actions have not been fully elucidated. We re-analyzed the data from the project Aspirin Resistance in Patients with Ischemic Atherothrombotic Diseases from April 2008 to June 2010. A total of 530 subjects were classified into 3 groups, including 40 patients without aspirin use, 24 patients taking 25-50 mg/d aspirin, and 466 patients taking 75-100 mg/d aspirin over 1 month. By 1:1:1 propensity score matching adjusting 15 primary clinical covariates, 51 patients (n = 17 per group) comprised the final sample. Hemostasis-related parameters and high platelet reactivity as measured by arachidonic acid-induced and adenosine diphosphate-induced light transmission aggregometry were compared in the 3 groups. A dose-dependent relationship was observed between aspirin and decreased high platelet reactivity incidence (PAA < 0.001, PADP < 0.01, respectively), decreased monocyte ratio (P = 0.052), increased antithrombin activity (P < 0.001), and increased platelet distribution width (P < 0.05). Aspirin at 25-50 mg/d is related to the lowest red blood cell (RBC) count, whereas 75-100 mg/d aspirin showed the highest RBC count among the 3 groups (4.52 ± 0.35 × 1012/L vs. 4.35 ± 0.57 × 1012/L vs. 4.80 ± 0.59 × 1012/L, P = 0.046). Our finding demonstrated that aspirin exerts its antithrombotic effects at least by antiplatelet function, enhancing antithrombin activity and suppressing monocytes in vivo. In addition, 3 blood cell types, namely RBCs, monocytes, and platelets, are involved in the aspirin antithrombotic mechanism. The cellular response to aspirin partially enhances the antithrombotic effects while partially inhibiting the effects.

Aspirin Use for Venous Thromboembolism Prevention Is Safe and Effective in Overweight and Obese Patients Undergoing Revision Total Hip and Knee Arthroplasty

BACKGROUND

Venous thromboembolism (VTE), defined as pulmonary embolism or deep venous thrombosis, is a rare but serious complication following revision total hip arthroplasty (RTHA) and revision total knee arthroplasty (RTKA). Previous studies show that obesity may be associated with an increased risk for pulmonary embolism, wound complications, and infection. With no current universal standard of care for VTE prophylaxis, we sought to determine whether aspirin prescribed (ASA) is safe and effective in obese patients undergoing RTHA/RTKA.

METHODS

A retrospective review of 1578 consecutive RTHA/RTKA cases (751 RTHAs and 827 RTKAs) was conducted identifying patients prescribed 325 or 81 mg ASA. Ninety-day postoperative VTE rates, bleeding, wound complications, deep infections, and mortality were collected. Cohorts were stratified according to body mass index (BMI): normal (18-24.9 kg/m²), overweight (25-29.9 kg/m²), obese (30-34.9 kg/m²), severely obese (35-39.9 kg/m²), and morbidly obese (≥40 kg/m²).

RESULTS

The cohort comprised of 335 patients with a normal BMI, 511 were overweight, 408 obese, 232 severely obese, and 92 morbidly obese. Total VTE rates were statistically similar between BMI groups (0.90% vs 0.78% vs 0.74% vs 0.43% vs 0%, P = .89). There were no differences in bleeding rates (0.90% vs 0% vs 0% vs 0.43% vs 0%, P = .08), wound complications (0.30% vs 0.20% vs 0.25% vs 0% vs 0%, P = .93), infection (1.49% vs 1.57% vs 0.98% vs 1.29% vs 1.09%, P = .66), or mortality (0% vs 0.20% vs 0% vs 0% vs 0%, P = .72).

CONCLUSION

ASA is safe and effective for VTE prevention in obese patients with similar complication rates to nonobese patients undergoing RTHA/RTKA.