Incidence and risk factors of deep vein thrombosis (DVT) after total hip or knee arthroplasty: a retrospective study with routinely applied venography

Risk factors for venous thromboembolism after primary total joint arthroplasty: An analysis of 7511 Taiwanese patients

BACKGROUND

The need for thromboprophylaxis in Asian patients after primary total joint arthroplasty (TJA) remains inconclusive. We aimed to identify the risk factors for venous thromboembolism (VTE) events following primary TJA in a Taiwanese population.

METHODS

From January 2010 to December 2019, we studied 7511 patients receiving primary TJA from a single surgeon. We validated the incidence and risk factors for 30- and 90-day symptomatic VTE events, including age, sex, body mass index (BMI), smoking, medical comorbidities, VTE history, presence of varicose veins, total knee arthroplasty (TKA) vs total hip arthroplasty (THA), unilateral vs bilateral procedure and receipt of VTE prophylaxis, transfusion, and length of stay.

RESULTS

The incidence of 30- and 90-day symptomatic VTE events was 0.33% and 0.44%, respectively. Multivariate regression analysis showed that BMI ≥30 (adjusted odds ratio (aOR): 4.862, 95% CI, 1.776-13.313), bilateral TJA procedure (aOR: 2.665, 95% CI, 1.000-7.104), and presence of varicose veins (aOR: 9.946, 95% CI, 1.099-90.024) were associated with increased odds of 30-day symptomatic VTE events. Age ≥77 years (aOR, 2.358, 95% CI, 1.034-5.381) and BMI ≥30 (aOR: 2.832, 95% CI, 1.039-7.721) were associated with increased odds of 90-day symptomatic VTE events.

CONCLUSION

Age ≥77 years, BMI ≥30, bilateral TJA procedure, or presence of varicose veins may require pharmacological thromboprophylaxis because such patients have a higher risk of VTE after primary TJA.

An analysis of the prevalence and risk factors of deep vein thrombosis in non-fracture patients awaiting total hip arthroplasty: a retrospective study of 1244 cases

BACKGROUND

Deep vein thrombosis (DVT) has been one of the most dangerous complications in total hip arthroplasty (THA). If a patient's pre-surgical DVT is overlooked, it can easily be mistaken for a post-operative thrombus and lead to an increased risk of DVT during and after surgery. This retrospective study was to explore the incidence and associated risk factors of deep vein thrombosis (DVT) in non-fracture patients before total hip arthroplasty (THA).

METHODS

From September 2015 to September 2020, 1242 patients admitted for THA were enrolled with 1120 patients (90.2%) for primary THA and 122 patients (9.8%) for revision THA. An experienced sonographer performed a bedside ultrasound to detect DVT in bilateral lower limbs preoperatively. Univariate and logistic regression analysis was performed to identify the independent risk factors.

RESULTS

38 patients (3.1%) were detected with preoperative DVT. Univariate analysis showed that age (P < 0.001), D-dimer level (P = 0.002), female patients (P = 0.016), revision THA (P < 0.001), Barthel Index score (P = 0.010) were significantly associated with preoperative DVT. In subgroup comparison, the incidence of DVT increased with age significantly (P < 0.001) and D-dimer level (P < 0.001). In logistic regression analysis, age ≥ 75 years old (odds ratio [OR] 3.678, 95% CI [2.197-18.721], P < 0.001), gender (OR 2.709, 95% CI [1.244-5.896], P = 0.012), higher D-dimer ≥ 0.5 mg/l (OR 6.841, 95% CI [2.197-18.721], P < 0.001) and revision THA (OR 2.240, 95% CI [1.143-5.372], P = 0.05) were confirmed as the independent risk factors.

CONCLUSIONS

The incidence of preoperative DVT in non-fracture patients was 3.1%, with 2.4% in primary THA and 9.0% in revision THA. Age ≥ 75 years old, female, D-dimer ≥ 0.5 mg/l, and revision THA were independent risk factors. When evaluating the risk factors associated with thrombus formation preoperatively, it is important to take these into account before surgery.

Incidence and risk factors of perioperative deep vein thrombosis in patients undergoing primary hip arthroplasty via the direct anterior approach

BACKGROUND

Deep vein thrombosis (DVT) is a frequent complication following hip arthroplasty. There still has been a lack of studies analyzing the perioperative risk factors of DVT following hip arthroplasty via direct anterior approach (DAA).

METHODS

Patients who underwent unilateral primary hip arthroplasty via DAA in our hospital from August 2015 to January 2022 were included. Patients' data, including demographic data, clinical features, past medical history, operative data, and laboratory data, were analyzed and compared between patients with and without DVT. Logistic regression analysis was conducted to identify the independent risk factors. Receiver operating characteristic (ROC) curve analysis was used to assess the best cutoff value of continuous variables with statistical significance.

RESULT

A total of 651 patients were included. The incidence of DVT before and after hip arthroplasty was 12.7% and 6.7%, respectively. Logistic regression analysis indicated that age ≥ 65 years (OR 4.594, 95% CI 1.994-10.587), women (OR 2.331, 95% CI 1.285-4.227), and cerebral infarction (OR 1.984, 95% CI 1.138-3.460) were independent risk factors for preoperative DVT. And age ≥ 65 years (OR 4.859, 95% CI 1.062-22.226), tumor (OR 3.622, 95% CI 1.108-11.841), and preoperative D-dimer (OR 1.040, 95% CI 1.004-1.078) were risk factors for postoperative DVT. The ROC curve analysis showed that the best cutoff value of preoperative D-dimer for the diagnosis of postoperative DVT is 1.44 mg/L.

CONCLUSIONS

The incidence of DVT in patients undergoing DAA hip arthroplasty was low and the occurrence of DVT before and after unilateral primary hip arthroplasty performed through DAA was related to multiple factors.

Development and validation of a nomogram for predicting the risk of immediate postoperative deep vein thrombosis after open wedge high tibial osteotomy

PURPOSE

This study aimed to identify independent risk factors for immediate postoperative deep vein thrombosis (DVT) in patients with open wedge high tibial osteotomy (OWHTO) and to develop and validate a predictive nomogram.

METHODS

Patients who underwent OWHTO for knee osteoarthritis (KOA) from June 2017 to December 2021 were retrospectively analyzed. Baseline data and laboratory test results were collected, and the occurrence of DVT in the immediate postoperative period was regarded as the study outcome event. Multivariable logistic regression identified independent risk factors associated with a higher incidence of immediate postoperative DVT. The predictive nomogram was constructed based on the analysis results. The stability of the model was further assessed in this study using patients from January to September 2022 as an external validation set.

RESULTS

741 patients were enrolled in the study, of which 547 were used in the training cohort and the other 194 for the validation cohort. Multivariate analysis revealed a higher Kellgren-Lawrence (K-L) grade (III vs. I-II OR 3.09, 95% CI 0.93-10.23. IV vs. I-II OR 5.23, 95% CI 1.27-21.48.), platelet to hemoglobin ratio (PHR) > 2.25 (OR 6.10, 95% CI 2.43-15.33), Low levels of albumin (ALB) (OR 0.79, 95% CI 0.70-0.90), LDL-C > 3.40 (OR 3.06, 95% CI 1.22-7.65), D-dimer > 1.26 (OR 2.83, 95% CI 1.16-6.87) and BMI ≥ 28 (OR 2.57, 95% CI 1.02-6.50) were the independent risk factors of immediate postoperative DVT. The concordance index (C-index) and Brier score of the nomogram were 0.832 and 0.036 in the training set, and the corrected values after internal validation were 0.795 and 0.038, respectively. The receiver-operating characteristic (ROC) curve, the calibration curve, the Hosmer-Lemeshow test, and the decision curve analysis (DCA) performed well in both the training and validation cohorts.

CONCLUSION

This study developed a personalized predictive nomogram with six predictors, which allows surgeons to stratify risk and recommended immediate ultrasound scans for patients with any of these factors.

LEVEL OF EVIDENCE

III.

A Comparison of the Caprini Score With an Institutional Risk Assessment Tool for Prediction of Venous Thromboembolism After Total Joint Arthroplasty at an Urban Tertiary Care Health Safety Net Hospital

Background

Patients undergoing total joint arthroplasty (TJA) are at increased risk for venous thromboembolism (VTE). Prediction tools such as the Caprini Risk Assessment Model (RAM) have been developed to identify patients at higher risk. However, studies have reported heterogeneous results when assessing its efficacy for TJA. Patients treated in an urban health safety net hospital have increased medical complexity, advanced degenerative joint disease, and severe disability prior to TJA increasing the risk of VTE. We hypothesize that use of a tool designed to account for these conditions-the Boston Medical Center (BMC) VTE score-will more accurately predict VTE in this patient population.

Methods

A retrospective case-control study was performed including subjects 18 years of age and older who underwent primary or revision TJA in an urban academic health safety net hospital. Patients with hemiarthroplasties, simultaneous bilateral TJA, and TJA after acute trauma were excluded. A total of 80 subjects were included: 40 who developed VTE after TJA (VTE+) and 40 who did not develop VTE (controls). Subjects were matched by age, gender, and surgical procedure.

Results

There was a statistically significant difference between the mean BMC VTE score for VTE+ and controls (4.40 and 3.13, respectively, P = .036). Conversely, there was no statistical difference between the mean Caprini scores for VTE+ and controls (9.50 and 9.35, respectively, P = .797).

Conclusions

In a health safety-net patient population, an institutional RAM-the BMC VTE score-was found to be more predictive of VTE than the modified Caprini RAM following TJA. The BMC-VTE score should be externally validated to confirm its reliability in VTE prediction in similar patient populations.

The application of Caprini Risk Assessment Model in evaluation of deep vein thrombosis for patients with end-stage osteoarthritis before arthroplasty

Background

Deep vein thrombosis (DVT) was a fatal complication of knee arthroplasty. We had neglected the risk factors of preoperative DVT although patients undergoing knee arthroplasty were at high risk for VTE. This study was to determine the risk factors for preoperative DVT and application of Caprini Risk Assessment Model (RAM) in patients with end-stage knee osteoarthritis (OA).

Methods

We retrospectively analyzed 1808 cases with end-stage knee OA undergoing primary knee arthroplasty from May 2015 to December 2020. Based on the results of ultrasonography in lower extremities, all patients were divided into non-DVT group and DVT group. Distribution of risk factors and risk levels were compared using χ² test between two groups. Binary logistic regression analysis was used to determine the risk factors and relationship of risk levels and preoperative DVT.

Results

The incidence of preoperative DVT was 5.53% (n = 100). Distribution of the study population by risk level was low, 4.09%; moderate, 23.95%; high, 66.98%; and highest 4.98%. Female (P = 0.002), age (P = 0.012), swollen legs (P = 0.035) and history of blood clots (P < 0.001) was correlated with preoperative DVT. Difference among four risk levels was significant (P = 0.007). Patients with highest risk level had statistically significant association with preoperative DVT (P = 0.005, OR = 2.93, 95%CI [1.375–6.246]).

Conclusion

The incidence of preoperative DVT was 5.53% in end-stage knee OA patients. The gender (female) and age were independent risk factors for preoperative DVT. The risk group classification by Caprini RAM was significantly associated with preoperative DVT. The usage of Caprini RAM before knee arthroplasty may be beneficial for prophylaxis of DVT.

Does diabetes mellitus increase the incidence of early thrombosis in deep vein following unicompartmental knee arthroplasty: a retrospective cohort study

Background

Many patients following unicompartmental knee arthroplasty (UKA) also suffer from diabetes mellitus, which may lead to an increased likelihood of postoperative deep venous thrombosis (DVT). Therefore, we evaluated whether DVT incidence would increase 3 days following UKA in diabetic patients.

Methods

Patients who underwent UKA from August 2018 to September 2021 in our hospital were retrospectively included. Age, gender, body mass index, hypertension, mode of anesthesia, surgery time, intraoperative blood loss, tourniquet pressure and time, and glycosylated hemoglobin concentration were recorded as confounders. We compared the incidence and type of DVT between non-diabetic and diabetic patients and evaluated the effect of glycosylated hemoglobin levels on DVT.

Results

Of all the 224 patients, 96 had diabetes and 128 did not. Within 3 days after surgery, DVT occurred in 25 cases in the diabetic group and 17 cases in the non-diabetic group (p < 0.05), and the difference mainly exists in the lower limbs on the surgical side. Logistic regression analysis demonstrated that the risk of DVT in the diabetic group was 4.50 times higher compared with the non-diabetic group. For every 1 unit increase of glycosylated hemoglobin, the incidence of DVT increased 2.35 times. Differences in age, gender, body mass index, hypertension, mode of anesthesia, surgery time, intraoperative blood loss, tourniquet pressure, and time between the two groups were not significant.

Conclusions

The incidence of DVT in diabetic patients within 3 days after UKA was significantly higher than that in non-diabetic patients and was proportional to the concentration of glycosylated hemoglobin.

A nomogram model to predict the venous thromboembolism risk after surgery in patients with gynecological tumors

OBJECTIVE

Venous thromboembolism (VTE) is a common post-surgical complication of gynecological malignant tumors that has serious implications on the prognosis and quality-of-life of patients. However, there exists only a few recognized specific evaluation models for the occurrence of VTE after gynecological malignant tumor surgery. We aimed to establish a nomogram model that could predict the probability of post-surgical VTE in patients with gynecological malignancies.

METHODS

We collected the clinical information of 673 patients who underwent surgery for gynecological malignant tumor in our hospital between January 2014 and May 2020. To reduce bias from confounding factors between groups, a 1:1 ratio propensity score matching (PSM) method was performed; meanwhile, univariate and multivariate analyses were applied to analyze the risk factors of VTE after surgeries. A nomogram prediction model was accordingly established and internally validated.

RESULTS

The predictors contained in the nomogram model included age, D-dimer value, body mass index (BMI), and surgical approach. The C-index of the model was 0.721 (95% confidence interval: 0.644-0.797), with good discrimination and calibration effect. The internally verified C-index value was 0.916. Decision curve analysis confirmed that the nomogram model was clinically useful when the incidence of thrombosis in patients was 10-75%.

CONCLUSIONS

Considering the risk factors of VTE after surgery for gynecological malignant tumor, a high-performance nomogram model was established and then validated to provide individual risk assessment and guide treatment decisions.

Effect of self-calf massage on the prevention of deep vein thrombosis after total knee arthroplasty: A randomized clinical trial

OBJECTIVE

Deep vein thrombosis (DVT) is a severe complication after total knee arthroplasty (TKA). Performing self-calf massage may decrease the incidence of DVT. The purpose of this study was to investigate whether self-calf massage is effective for preventing DVT after TKA.

METHOD

In all, 165 patients participated in the present study. Patients were randomized to one of two groups: the self-calf massage group or the control group. In the control group, patients started regular physical therapy. In the self-calf massage group, in addition to regular physical therapy, patients were instructed to massage their calf muscles 30 times from the distal to proximal side. This procedure was repeated three times and was completed in 2 mins during the 2 days following TKA. All patients were evaluated for DVT on postoperative day 3 using lower limb vein ultrasonography.

RESULTS

The incidence of DVT was significantly lower in the self-calf massage group than in the control group. Self-calf massage was associated with a lower incidence of DVT, whereas age and female sex were risk factors for DVT.

CONCLUSION

This study showed that the self-calf massage may be beneficial for the prevention of DVT after TKA.

Enhanced recovery short-stay hip and knee joint replacement program improves patients outcomes while reducing hospital costs

INTRODUCTION

An attractive option to reduce hospital length of stay (LOS) after hip or knee joint replacement (THA, TKA) is to follow the Enhanced Recovery After Surgery principles (ERAS) to improve patient experience to a level where they will feel confident to leave for home earlier. The objective of this study was to evaluate the implementation of short-stay protocol following the ERAS principles.

HYPOTHESIS

We hypothesized that our ERAS THA and TKA short-stay protocol would result in a lower complication rate, shorter hospital LOS and reduced direct health care costs compared to our standard procedure.

MATERIAL AND METHODS

We compared the complications rated according to Clavien-Dindo scale, hospital LOS and costs of the episode of care between a prospective cohort of 120 ERAS short-stay THA or TKA and a matched historical control group of 150 THA or TKA.

RESULTS

Significantly lower rate of Grade 1 and 2 complications in the ERAS short-stay group compared with the standard group (mean 0.8 vs 3.0, p<0.001). No difference was found between the 2 groups for Grade 3, 4, or 5 complications. The mean hospital LOS for the ERAS short-stay group decreased by 2.8 days for the THAs (0.1 vs 2.9 days, p<0.001) and 3.9 days for the TKAs (1.0 vs 4.9 days, p<0.001). The mean estimated direct health care costs reduction with the ERAS short-stay protocol was 1489 CAD per THA and 4158 CAD per TKA.

DISCUSSION

In many short-stay protocols, focus has shifted from ERAS goals of a reduction in complications and improved recuperation to use length of stay as the main factor of success. Implementation of an ERAS short-stay protocol for patients undergoing THA or TKA at our institution resulted not only in reduced hospital LOS, but also in improved patient care and reduced direct health care costs.

LEVEL OF EVIDENCE

Level II.

Factors Influencing Elastographically Determined Remodeling of Venous Thrombi

OBJECTIVES

To verify whether elastographically determined remodeling of venous obliterating material formed during sclerotherapy is influenced by patient-specific factors.

METHODS

The study included 60 patients who underwent sclerotherapy for venous insufficiency. Elastographic parameters of obliterating material, including relative vascular cross sections (percent) with the highest (red), intermediate (green), and lowest elasticity (blue), determined 7 ± 1, 14 ± 2, and 21 ± 2 days after sclerotherapy, were analyzed against the patients' ages, sexes, physical activity levels, and pain severities.

RESULTS

The patients included 45 women and 15 men with a mean age ± SD of 51.2 ± 14.7 years. A significant correlation was observed between the age of the patients and the relative area of the vessel highlighted in red during the third control visit (R = 0.289; P = .025). The proportion of men in whom the elastographic structure of venous obliterating material during the second visit was classified as mixed was higher than that of women (66.7% versus 28.9%; P = .032). During the third visit, the proportion of patients with low physical activity in whom the elastographic structure of venous obliterating material was classified as fibrous turned out to be lower than the respective percentages of patients with moderate and high activity levels (12.0% versus 35.0% versus 46.7%; P = .045). However, none of these effects was observed systematically throughout the whole follow-up period.

CONCLUSIONS

The time to complete organization of venous obliterating material may be longer in older patients, women, and patients with lower levels of physical activity, but these factors seem to influence the thrombus structure solely at specific time points in its evolution. Nevertheless, they should be considered during elastographic assessments of thrombus age.

Ketamine reduces pain and opioid consumption after total knee arthroplasty: A meta-analysis of randomized controlled studies

OBJECTIVE

To examine the analgesic efficacy and safety of ketamine after total knee arthroplasty.

METHODS

We searched for all articles on ketamine in patients with total knee arthroplasty in electronic databases, including PubMed, Embase, Ovid, Cochrane Library, Web of Science, CNKI, Wanfang Data, and VIP, up to the February 2019. Randomized controlled trials comparing ketamine and the placebo for pain management after total knee arthroplasty were utilized. The outcome measurements consist of the pain score, opioid consumption, length of hospitalization and postoperative complications. All data analyses were conducted using STATA 13.0. Cochrane Collaboration's tool was adopted to assess the risk of bias.

RESULTS

A total of six randomized controlled trials were included in the meta-analysis. The present meta-analysis demonstrated that there were significant differences between the two groups regarding the pain score within the first 24 postoperative hours. Ketamine was associated with a significant reduction of cumulative morphine consumption. Notably, ketamine could significantly decrease the incidence of nausea and vomiting without increasing the risk of thrombosis.

CONCLUSION

Ketamine is effective in reducing pain and cumulative morphine consumption during the early post-operative period after total knee arthroplasty. In addition, the use of ketamine is associated with a lower incidence of adverse effects.

The efficacy and safety of modified Robert Jones bandage in total knee arthroplasty: A meta-analysis of randomized-controlled trials

BACKGROUND

The efficacy of modified Robert Jones bandage in primary total knee arthroplasty (TKA) is controversial. On the basis of randomized controlled trials (RCTs), this systematic review and meta-analysis was conducted to evaluate the modified Robert Jones bandage in TKA.

METHODS

The electronic databases of EMBASE, PubMed, Web of Science and Cochrane Library were searched from the inception to November 2018 for all relevant English studies. The outcome measurements consisted of total blood loss, hemoglobin decline, transfusion rates, pain score, range of motion, length of hospitalization, knee circumference difference, and adverse effects. Data were analyzed using STATA 14.0 software (The Cochrane Collaboration, Oxford, United Kingdom).Quality assessment was conducted according to the Cochrane Handbook for systematic review of interventions.

RESULTS

A total of 5 randomized controlled trials (RCTs) were included in the systematic review and meta-analysis. The present meta-analysis indicated that there were no significant differences in terms of total blood loss, hemoglobin decline, transfusion rates, pain score, range of motion, length of hospitalization, knee circumference difference, or adverse effects.

CONCLUSIONS

Although published articles have shown improved outcome of blood loss, pain, and knee swelling after application of a modified Robert Jones bandage, our study suggest the use of modified Robert Jones bandage may not be necessary after primary TKA.

Systematic review of risk prediction scores for venous thromboembolism following joint replacement

BACKGROUND

Venous thromboembolism (VTE) is an important cause of morbidity and a preventable cause of deaths following lower limb joint replacement. Risk prediction scores that help to predict individual VTE risk following lower limb joint replacement may inform the development of preventive strategies and guide treatment decisions. We aimed to systematically review the evidence on the development and/or validation of risk prediction scores for VTE following lower limb joint replacement.

METHODS

Population-based studies that have developed and/or validated a risk prediction score for VTE following hip or knee replacement and randomised controlled trials (RCTs) that have evaluated the clinical impact of a score were searched for in MEDLINE, Embase, Web of Science, and The Cochrane Library to April 2018.

RESULTS

Five observational cohort studies describing five risk scores were included. No RCTs were identified. The number of component variables in a single risk score ranged from 5 to 26. Three risk scores comprised 5-8 component variables. None of the studies reported calibration or discrimination statistics. Two risk scores were externally validated in single-institution cohorts and were reported to perform well. One study evaluated the general surgery Caprini risk score in primary hip and knee replacement patients and did not find it useful for VTE risk stratification.

CONCLUSIONS

Few VTE risk prediction scores in lower limb joint replacement exist and these have methodological issues, have been inadequately reported, not been sufficiently validated, and their impact on patient outcomes and decision making is unknown. Research is urgently warranted in the field. Systematic review registration: PROSPERO 2018: CRD42018088712.

What are the incidence and risk factors of in-hospital mortality after venous thromboembolism events in total hip and knee arthroplasty patients?

Background

Pulmonary embolism and deep vein thrombosis, together referred to as venous thromboembolism (VTE), are serious and potentially preventable complications after total hip arthroplasty and total knee arthroplasty. The aim of this study was to investigate the incidence of mortality after VTE events and assess the risk factors that are associated with it.

Methods

The Nationwide Inpatient Sample was used to estimate the total number of total hip arthroplasty, total knee arthroplasty, VTE events, and mortality using the International Classification of Diseases, Ninth Revision procedure codes from 2003 to 2012. Patients' demographics, Elixhauser, and Charlson comorbidity indices were used to identify the risk factors associated with in-hospital VTEs and mortality.

Results

A total of 1,805,621 THAs and TKAs were included. The overall rate of VTE was 0.93%. The in-hospital mortality rate among patients with VTEs was 7.1% vs 0.30% in patients without VTEs (P-value < .0001). The risk factors for mortality after VTE events in descending order were as follows: hypercoagulable state (odds ratio [OR]: 5.3, 95% confidence interval [CI]: 3.6-5.8), metastatic cancer (OR: 5.2, 95% CI: 3.3-5.6), myocardial infarction (OR: 4.2, 95% CI: 2.3-4.7), peripheral vascular disease (OR: 3.6, 95% CI: 3.2-4.0), cardiac arrhythmias (OR: 3.2, 95% CI: 1.6-4.3), advanced age (OR: 3.1, 95% CI: 2.3-3.7), electrolyte disorders (OR: 3.1, 95% CI: 2.2-3.6), pulmonary circulation disorders (OR: 2.9, 95% CI: 2.6-3.3), depression (OR: 2.8, 95% CI: 1.6-3.4), complicated diabetes (OR: 2.7, 95% CI: 2.1-3.2), weight loss (OR: 2.6, 95% CI: 2.2-3.3), renal failure (OR: 2.6, 95% CI: 1.7-3.5), chronic pulmonary disease (OR: 2.5, 95% CI: 1.3-3.1), valvular disease (OR: 2.4, 95% CI: 1.8-2.7), liver disease (OR: 1.7, 95% CI: 1.2-1.9), and obesity (OR: 1.6, 95% CI: 1.5-1.9).

Conclusions

In-hospital VTE has a significant in-hospital mortality rate. Several of the identified risk factors in this study are modifiable preoperatively. We strongly urge the orthopaedic community to be cognizant of these risk factors and emphasize on optimizing patients' comorbidities before an elective arthroplasty.

Fibrin polymerization simulation using a reactive dissipative particle dynamics method

The study on the polymerization of fibrinogen molecules into fibrin monomers and eventually a stable, mechanically robust fibrin clot is a persistent and enduring topic in the field of thrombosis and hemostasis. Despite many research advances in fibrin polymerization, the change in the structure of fibrin clots and its influence on the formation of a fibrous protein network are still poorly understood. In this paper, we develop a new computational method to simulate fibrin clot polymerization using dissipative particle dynamics simulations. With an effective combination of reactive molecular dynamics formularies and many body dissipative particle dynamics principles, we constructed the reactive dissipative particle dynamics (RDPD) model to predict the complex network formation of fibrin clots and branching of the fibrin network. The 340 kDa fibrinogen molecule is converted into a spring-bead coarse-grain system with 11 beads using a topology representing network algorithm, and using RDPD, we simulated polymerization and formation of the fibrin clot. The final polymerized structure of the fibrin clot qualitatively agrees with experimental results from the literature, and to the best of our knowledge this is the first molecular-based study that simulates polymerization and structure of fibrin clots.

Rivaroxaban versus nadroparin for preventing deep venous thrombosis after total hip arthroplasty following femoral neck fractures: A retrospective comparative study

Objective This study was performed to evaluate the efficacy of rivaroxaban versus nadroparin for preventing deep venous thrombosis (DVT) in elderly patients with osteoporosis undergoing initial total hip arthroplasty (THA) for femoral neck fractures. Methods Prospectively maintained databases were reviewed to retrospectively compare elderly patients with osteoporosis who underwent initial THA for femoral neck fractures from 2007 to 2015. The patients received peroral rivaroxaban at 10 mg/day for 2 weeks or subcutaneous injections of nadroparin at 0.3 mL/day for 2 weeks until the primary analysis cut-off date. The time to first on-study DVT was the primary endpoint. Results In total, 399 patients were included (rivaroxaban group: n=200; mean age, 70.20 ± 9.16 years and nadroparin group: n = 199; mean age, 69.90 ± 8.87 years), with a mean 3-year follow-up. The time to first on-study DVT was significantly longer in the rivaroxaban than nadroparin group (12 and 5 days, respectively). The incidence of DVT within the 2-week follow-up was significantly higher in the nadroparin than rivaroxaban group (6.8% and 19.7%, respectively), but this difference was no longer present at the final follow-up. Conclusion Rivaroxaban was associated with a significant reduction in the occurrence of first on-study DVT compared with nadroparin.

The risk of deep vein thrombosis in total joint patients compared to orthopaedic trauma patients: Need for new prevention guidelines

BACKGROUND

The development of Deep Vein Thrombosis (DVT) is a major concern following orthopaedic surgery. No study has yet to compare the rate and risk factors for DVT between total joint and orthopaedic trauma patients. To evaluate if DVT prophylaxis for trauma should differ from total joints, we explored the rate and risk factors for DVT between both cohorts.

METHODS

Using a CPT code search from 2005 to 2013 in the ACS-NSQIP database, 150,657 orthopaedic total joint patients and 44,594 orthopaedic trauma patients were identified. DVT complications, patient demographics, preoperative comorbidities, and surgical characteristics were collected for each patient. A chi-squared test was used to compare the risk factors for DVT between orthopaedic trauma and total joint patients. A multivariable logistic regression model was built to adjust for comorbidities for each cohort.

RESULTS

The rate of DVT diagnosis in the total joint population was 0.8% (N = 1186) and 0.98% (N = 432) in the orthopaedic trauma population (p = 0.57). After controlling for individual comorbidities, dyspnea, peripheral vascular disease, and renal failure were significant risk factors for DVT in total joint patients (p < 0.05), whereas age, ascites and steroid use were significant risk factors for DVT in orthopaedic trauma patients (p < 0.05).

CONCLUSIONS

Historically, the risks for DVT in total joints have been emphasized, yet based on our results, the incidence of DVT is the same for orthopaedic trauma. However, the risk factors varied. It is therefore important to consider specialty-specific DVT prophylaxis for orthopaedic trauma patients in order to improve care and reduce postoperative complications.

Release of the tourniquet immediately after the implantation of the components reduces the incidence of deep vein thrombosis after primary total knee arthroplasty

Objectives

The length of the tourniquet time during total knee arthroplasty (TKA) is related to the incidence of post-operative deep vein thrombosis (DVT). Our aim in this study was to investigate the effect of the early release of the tourniquet on the incidence of DVT in patients undergoing TKA.

Methods

A total of 200 patients who underwent TKA between November 2015 and November 2016 were prospectively enrolled. The tourniquet was inflated before surgery and released immediately after the introduction of the components (early release group). This group was compared with a retrospective cohort of 200 primary TKAs, in which the tourniquet was released after the dressings had been applied (late release group). The presence of a DVT was detected using bilateral lower limb ultrasonography. Peri-operative clinical and follow-up data were collected for analysis.

Results

The incidence of DVT in the early release group (9 of 196, 4.6%) was significantly lower compared with the late release group (24 of 200, 12%; odds ratio (OR) 0.35, 95% confidence interval (CI) 0.16 to 0.78, p = 0.008). The incidence of proximal DVT in the early release group (1 of 196 (0.5%)) was significantly lower than in the late release group (8 of 196, 4%; OR 0.12, 95% CI 0.02 to 0.99, p = 0.020). Although the mean intra-operative blood loss was higher in the early release group, the mean post-operative drainage, total blood loss, transfusion requirements and complications were not significantly different in the two groups.

Conclusion

In patients who undergo TKA, releasing the tourniquet early is associated with a decreased incidence of DVT, without increasing the rate of complications.

Cite this article: Bone Joint Res 2017;6:535–541.