Rivaroxaban does not impair fracture healing in a rat femur fracture model: an experimental study

Horizontal Alveolar Ridge Splitting and Expansion

When considering placing dental implants in atrophic edentulous sites, there may be inadequate site width and little or no vertical bone loss. Any of several surgical procedures can augment these sites. Extracortical augmentation is done by applying graft material against the cortical bone. This technique expects progenitor cells to migrate outside the bony ridge's confines and form new bone. Another method entails ridge splitting and expansion to create space for osteogenesis and, when possible, implant placement. This may be a better method for horizontal ridge augmentation. The ridge is split, separating the facial and lingual cortices for a complete bone fracture. The patient's osseous cells can then migrate into the created space from the exposed medullary bone to form bone. The technique can be preferably performed flapless so the intact periosteum maintains a blood supply to ensure appropriate healing.

How I treat pediatric venous thromboembolism in the DOAC era

ABSTRACT

The direct oral anticoagulants (DOACs) rivaroxaban and dabigatran are newly licensed for the treatment and prevention of venous thromboembolism (VTE) in children and mark a renaissance in pediatric anticoagulation management. They provide a convenient option over standard-of-care anticoagulants (heparins, fondaparinux, and vitamin K antagonists) because of their oral route of administration, child-friendly formulations, and significant reduction in monitoring. However, limitations related to therapeutic monitoring when needed and the lack of approved reversal agents for DOACs in children raise some safety concerns. There is accumulating experience of safety and efficacy of DOACs in adults for a broad scope of indications; however, the cumulative experience of using DOACs in pediatrics, specifically for those with coexisting chronic illnesses, is sparse. Consequently, clinicians must often rely on their experience for treating VTE and extrapolate from data in adults while using DOACs in children. In this article, the authors share their experience of managing 4 scenarios that hematologists are likely to encounter in their day-to-day practice. Topics addressed include (1) appropriateness of indication; (2) use for special populations of children; (3) considerations for laboratory monitoring; (4) transition between anticoagulants; (5) major drug interactions; (6) perioperative management; and (7) anticoagulation reversal.

Effect of direct oral anticoagulant dabigatran on early bone healing: An experimental study in rats

Background

Dabigatran belongs to the new generation of direct oral anticoagulants (DOACs). Its advantages are oral administration and no need for international normalized ratio (INR) monitoring. Although its use has increased, its potential side effects on bone healing and remodeling have not been fully investigated. The present study aimed to evaluate the possible effects of dabigatran on early bone healing.

Methods

Sixteen male Wistar rats were divided into two groups; in group A, 20-mg/kg dabigatran dose was administered orally daily for 15 days, while group B served as a control. Two circular bone defects (d=6 mm) were created on either side of the parietal bones. Two weeks after surgery and euthanasia of the animals, tissue samples (parietal bones that contained the defects) were harvested for histological and histomorphometric analysis. Statistical analysis was performed with a significance level of α=0.5.

Results

No statistically significant differences were found between the two groups regarding the regenerated bone (21.9% vs. 16.3%, P=0.172) or the percentage of bone bridging (63.3% vs. 53.5%, P=0.401).

Conclusion

Dabigatran did not affect bone regeneration, suggesting that it might be a safer drug compared to older anticoagulants known to lead to bone healing delay.

Risk of osteoporosis in patients treated with direct oral anticoagulants vs. warfarin: an analysis of observational studies

Aims

Evidence on the association between the risk of new-onset osteoporosis and oral anticoagulants remains controversial. We aimed to compare the risk of osteoporosis associated with the use of direct oral anticoagulants (DOACs) with that associated with warfarin use.

Methods

Studies published up to 15 March 2023 that investigated the association between the use of DOACs and warfarin and the incidence of osteoporosis were identified by online searches in PubMed, Embase, the Cochrane Library, and Web of Science conducted by two independent investigators. Random-effects or fixed-effect models were employed to synthesize hazard ratios (HRs)/relative ratios (RRs) with 95% confidence intervals (CIs) for estimating the risk of osteoporosis correlated with DOAC and warfarin prescriptions (PROSPERO No. CRD42023401199).

Results

Our meta-analysis ultimately included four studies involving 74,338 patients. The results suggested that DOAC use was associated with a significantly lower incidence of new-onset osteoporosis than warfarin use (pooled HR: 0.71, 95% CI: 0.57 to 0.88, p < 0.001, I 2: 85.1%). Subanalyses revealed that rivaroxaban was associated with a lower risk of osteoporosis than both warfarin and dabigatran. In addition, DOACs were associated with a lower risk of developing osteoporosis than warfarin in both male and female patients, in patients with atrial fibrillation (AF), and in patients who underwent therapy for > 365 days.

Conclusion

DOAC users experienced a lower incidence of osteoporosis than warfarin users. This study may give us insight into safe anticoagulation strategies for patients who are at high risk of developing osteoporosis.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO, identifier CRD42023401199.

Fracture risks in patients with atrial fibrillation treated with different oral anticoagulants: a meta-analysis and systematic review

Aims

evidence on the difference in fracture risks for patients with atrial fibrillation (AF) receiving direct oral anticoagulants (DOACs) versus warfarin remains controversial. We aim to compare the fracture risks between the DOAC and warfarin prescriptions among the AF patients.

Methods and Results

we systematically searched PubMed, EMBASE, the Cochrane Library and Web of Science up to 19 April 2021 for relevant studies. And the observational studies regarding the relationship between the DAOC versus warfarin prescriptions and fracture risks among the patients with AF were included in this meta-analysis. Two investigators independently screened the articles and extracted the relevant data. A random- or fixed-effect model was applied to calculate the pooled hazard ratio/relative ratios with 95% confidence intervals of fracture risks associated with the DOAC and warfarin prescriptions. Six studies comprising 351,208 patients and 9,424 fractures were included in this meta-analysis. Overall, the AF patients treated with DOACs tend to present a lower risk of any fracture compared with those treated with warfarin (relative ratio: 0.82, 95% confidence interval (CI): 0.74–0.91). Sub-analyses for each individual DOAC indicate that apixaban and rivaroxan are associated with lower risk of any fracture compared with warfarin (HR: 0.75, 95% CI: 0.60–0.92, and HR: 0.79, 95% CI: 0.71–0.88, respectively).

Conclusion

this meta-analysis suggests that DOAC users have a lower risk of fractures than the warfarin users. The results of this study may provide optimal anticoagulation opportunities for AF patients with high fracture risk factors.

Bone density and quality in patients treated with direct-acting oral anticoagulants versus warfarin

INTRODUCTION

Direct-acting oral anticoagulants (DOACs) are therapeutic alternatives to warfarin that act independently of vitamin K, thus not affecting bone matrix formation. The aim of this study was to compare bone mineral density (BMD) and microarchitecture in patients treated with DOACs versus warfarin.

METHODS

Cross-sectional, observational study in patients using oral anticoagulants for >1 year and a paired control group (CG). Based on the type of anticoagulant used, the patients were grouped into a DOAC (DOACG) or warfarin (WG) group. All patients filled out a questionnaire and underwent BMD evaluation and trabecular bone score (TBS) measurement.

RESULTS

In all, 150 patients were included (50 patients in each group). The mean age was 60.49 ± 7.48 years, and most participants were men (64%). The most frequent comorbidities were hypertension, dyslipidemia, and hyperglycemia (comparison between groups p > 0.05). Low bone mass was diagnosed in 42%, 50%, and 66% of the patients in the CG, DOACG, and WG, respectively (p = 0.012). On logistic regression analysis, BMD was associated with body mass index (BMI; odds ratio [OR] 0.846, 95% confidence interval [CI] 0.763-0.926, p = 0.001), creatinine level (OR 0.024, 95%CI 0.001-0.434, p = 0.017), and TBS value (OR 17.777, 95%CI 4.526-96.903, p = 0.000). The mean TBS decreased progressively from the CG to the DOACG and WG (1.328 ± 0.112, 1.264 ± 0.138, and 1.203 ± 0.112, respectively, p < 0.001). On multivariate linear regression, negative predictors of TBS included warfarin use (-0.06, 95%CI -0.11 to -0.02, p = 0.006), BMI (-0.01, 95%CI -0.01 to -0.00, p < 0.001), and hyperglycemia (-0.07, 95%CI -0.11 to -0.03, p = 0.003), while positive predictors were an active IPAQ classification (0.06, 95%CI 0.01-0.11, p = 0.029) and family history of hip fracture (0.07, 95%CI 0.01-0.14, p = 0.029).

CONCLUSION

Patients using anticoagulants have lower BMD and TBS values compared with controls. This negative effect on bone was more pronounced with warfarin, but was also seen with DOACs.

Non-vitamin K oral anticoagulants and risk of fractures: a systematic review and meta-analysis

AIMS

Comparative fracture risk for non-vitamin K antagonist oral anticoagulants (NOACs) and vitamin K antagonists (VKAs) among patients with atrial fibrillation (AF) remains unclear. This study aimed to provide summary relative risk (RR) estimates for associations between NOACs vs. VKAs and fracture risk.

METHODS AND RESULTS

PubMed, EMBASE, and Cochrane Library were searched from 2010 to 26 May 2020. Observational studies investigating the association between NOACs vs. VKAs and fracture risk in patients with AF were included. The adjusted effect estimates were pooled using the DerSimonian-Laird random effects models. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and the Meta-analysis of Observational Studies in Epidemiological (MOOSE) guidelines were followed. Five observational studies comprising 269 922 patients and 4289 fractures were included. Non-vitamin K antagonist oral anticoagulants use was associated with a lower risk of any fractures compared to VKAs use, with moderate heterogeneity [pooled RR = 0.83, 95% confidence interval (CI): 0.75-0.92, P < 0.001, I2 = 73.0%]. When comparing individual NOAC to VKAs, a statistically significant lower risk of any fractures was found for rivaroxaban (pooled RR = 0.79, 95% CI: 0.71-0.88, P < 0.001, I2 = 55.2%) and apixaban (pooled RR = 0.75, 95% CI: 0.60-0.92, P = 0.007, I2 = 54.5%), but not dabigatran (pooled RR = 0.87, 95% CI: 0.74-1.01, P = 0.061, I2 = 74.6%). No differences were observed in all head-to-head comparisons between NOACs.

CONCLUSION

This large meta-analysis suggests that NOACs use was associated with a lower risk of fractures compared with VKAs. Fracture risks were similar between NOACs. These findings may help inform the optimal anticoagulant choice for patients with AF at high risk of fracture.

Effects of Anticoagulant Medication on Bone-Healing

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A substantial proportion of patients undergoing orthopaedic care are prescribed some form of anticoagulant medication, whether for perioperative venous thromboembolism prophylaxis or chronic anticoagulation in the setting of a cardiac or other condition.

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An abundance of preclinical data suggests that many commonly used anticoagulant medications may have a harmful effect on bone-healing.

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The orthopaedic surgeon should be informed and mindful of the added variable that anticoagulation may play in the outcomes of fracture treatment and bone-healing.

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Heparin and warfarin appear to have a greater detrimental impact than low-molecular-weight heparin. Factor Xa inhibitors may confer the least risk, with some studies even suggesting the potential for enhancement of bone-healing.

Fracture risks among patients with atrial fibrillation receiving different oral anticoagulants: a real-world nationwide cohort study

AIMS

To evaluate the fracture risk among patients with atrial fibrillation (AF) treated with non-vitamin K antagonist oral anticoagulants (NOACs) or warfarin.

METHODS AND RESULTS

We conducted a real-world nationwide retrospective cohort study using Taiwan's National Health Insurance Research Database. All adult patients in Taiwan newly diagnosed with AF between 2012 and 2016 who received NOACs or warfarin were enrolled and followed up until 2017. Patients treated with NOACs were sub-grouped according to the NOAC used (dabigatran, rivaroxaban, and apixaban). Propensity score matching was performed for each head-to-head comparison. Cox regression analysis, with a shared frailty model, was used to calculate the adjusted hazard ratios (aHRs) for hip, vertebral, and humerus/forearm/wrist fractures. After matching, 19 414 patients were included (9707 in each NOAC and warfarin groups). The median follow-up time was 2.4 years. Compared with warfarin, NOACs were associated with a reduced fracture risk [aHR = 0.84, 95% confidence interval (CI) = 0.77-0.93; P < 0.001]. Sub-analyses revealed that each NOAC, namely dabigatran (aHR = 0.88, 95% CI = 0.78-0.99; P = 0.027), rivaroxaban (aHR = 0.81, 95% CI = 0.72-0.90; P < 0.001), and apixaban (aHR = 0.67, 95% CI = 0.52-0.87; P = 0.003), had a reduced fracture risk. Analyses including all eligible patients, without propensity score matching, generated similar results.

CONCLUSION

Compared with warfarin, NOAC was associated with a reduced fracture risk among AF patients. Therefore, if oral anticoagulants are indicated, NOACs rather than warfarin should be considered to lower the risk of fractures. However, further studies are needed to investigate the underlying mechanisms and elucidate causality.

Fracture Risks in Patients Treated With Different Oral Anticoagulants: A Systematic Review and Meta-Analysis

Background Evidence on the differences in fracture risk associated with non-vitamin K antagonist oral anticoagulants (NOAC) and warfarin is inconsistent and inconclusive. We conducted a systematic review and meta-analysis to assess the fracture risk associated with NOACs and warfarin. Methods and Results We searched PubMed, Embase, Cochrane Library, Scopus, Web of Science, and ClinicalTrials.gov from inception until May 19, 2020. We included studies presenting measurements (regardless of primary/secondary/tertiary/safety outcomes) for any fracture in both NOAC and warfarin users. Two or more reviewers independently screened relevant articles, extracted data, and performed quality assessments. Data were retrieved to synthesize the pooled relative risk (RR) of fractures associated with NOACs versus warfarin. Random-effects models were used for data synthesis. We included 29 studies (5 cohort studies and 24 randomized controlled trials) with 388 209 patients. Patients treated with NOACs had lower risks of fracture than those treated with warfarin (pooled RR, 0.84; 95% CI, 0.77-0.91; P<0.001) with low heterogeneity (I²=38.9%). NOACs were also associated with significantly lower risks of hip fracture than warfarin (pooled RR, 0.89; 95% CI, 0.81-0.98; P=0.023). A nonsignificant trend of lower vertebral fracture risk in NOAC users was also observed (pooled RR, 0.74; 95% CI, 0.54-1.01; P=0.061). Subgroup analyses for individual NOACs demonstrated that dabigatran, rivaroxaban, and apixaban were significantly associated with lower fracture risks. Furthermore, the data synthesis results from randomized controlled trials and real-world cohort studies were quite consistent, indicating the robustness of our findings. Conclusions Compared with warfarin, NOACs are associated with lower risks of bone fracture.

Clinical Risk Factors and Prognostic Impact of Osteoporosis in Patients With Chronic Heart Failure

BACKGROUND

The clinical significance of osteoporosis in chronic heart failure (CHF) remains unclear.Methods and Results:A total of 303 CHF patients (75 years, [interquartile range (IQR) 66-82 years]; 41% female) were retrospectively examined. Bone mineral densities (BMDs) at the lumbar spine, femoral neck, and total femur were measured by using dual-energy X-ray absorptiometry (DEXA), and osteoporosis was diagnosed when the BMD at any of the 3 sites was <70% of the Young Adult Mean percentage (%YAM). The prevalence of osteoporosis in CHF patients was 40%. Patients with osteoporosis were older (79 [IQR, 74-86] vs. 72 [IQR, 62-80] years), included a large percentage of females, had slower gait speed and had a lower body mass index. Multivariate logistic regression analysis indicated that sex, BMI, gait speed, loop diuretics use and no use of direct oral anticoagulants (DOACs) were independently associated with osteoporosis. Kaplan-Meier survival curves showed that the rate of death and heart failure hospitalization was higher in patients with osteoporotic BMD at 2 or 3 sites than in patients without osteoporosis (hazard ratio 3.45, P<0.01). In multivariate Cox regression analyses, osteoporotic BMD at 2 or 3 sites was an independent predictor of adverse events after adjustment for prognostic markers.

CONCLUSIONS

Loop diuretics use and no DOACs use are independently associated with osteoporosis in CHF patients. Osteoporosis is a novel predictor of worse outcome in patients with CHF.

Altered cell surface receptor dynamics and circulatory occurrence of neutrophils in a small animal fracture model

INTRODUCTION

Excessive activation of the immune response after femoral fractures and fracture fixation is potentially associated with the development of systemic and local complications, particularly in multiple trauma patients. A dysregulated function of neutrophils, the most prevailing immune cells in circulation, has been discussed as a central pathophysiological background for these unfavourable post-traumatic courses. Our aim was to investigate alterations in activity and functionality as expressed by the cell surface receptor dynamics of circulatory neutrophils after femoral fracture and intramedullary stabilization.

MATERIAL AND METHODS

After intramedullary stabilization, an isolated femur fracture was induced in 18 Sprague-Dawley rats. Animals were terminated at different time points, i.e. after 3 (n = 5, group 3d), 7 (n = 5, group 7d) and 14 (n = 5, Group 14d) days and grouped accordingly. Additionally, baseline measurements were performed in one control animal per study group (n = 3) after anaesthesia induction and termination, without prior intramedullary nailing and fracture induction. The numbers and cell surface expression of CD11b, CD11a, CD62 L, and CD49d of circulating neutrophils were compared between groups.

RESULTS

Neutrophil numbers were significantly reduced at 3 days compared with baseline measurements (1.2 × 10⁵ vs. 6.3 × 10⁵ cells/mL, p < 0.01). By day 7, neutrophil counts significantly increased back to homeostatic levels (p < 0.05). At day 3, CD11b-expression was significantly reduced, whereas CD11a-expression was increased compared with the baseline measurements (p < 0.05). At day 7, the circulatory neutrophil pool exhibited a unique CD11b^high/CD11a^high-neutrophil subset showing a significantly increased co-expression of CD49d. The expression of CD62 L did not change significantly throughout the experiment compared with baseline measurements.

CONCLUSIONS

This descriptive small animal fracture study is the first to show that an intramedullary stabilized femur fracture is associated with a temporary reduction in circulatory neutrophil count and concurrent changes in circulatory neutrophil function. Moreover, we demonstrated that the restoration to homeostatic neutrophil activation status occurs concomitantly with the appearance of a novel neutrophil subtype (CD11b^high/CD11a^high) in circulation. Our fundamental new findings of the changes in circulatory neutrophil count and functionality after trauma form an excellent basis for future studies to further elucidate the role of neutrophils as activators and regulators of different post-traumatic processes, potentially resulting in local (e.g., fracture healing disturbances) or systemic (e.g., MODS) complications. This might result in the development of specific therapies to reduce adverse outcomes after trauma.

Association Between Treatment With Apixaban, Dabigatran, Rivaroxaban, or Warfarin and Risk for Osteoporotic Fractures Among Patients With Atrial Fibrillation: A Population-Based Cohort Study

BACKGROUND

It is unclear whether anticoagulant type is associated with the risk for osteoporotic fracture, a deleterious complication of anticoagulants among patients with atrial fibrillation (AF).

OBJECTIVE

To compare the risk for osteoporotic fracture between anticoagulants.

DESIGN

Population-based cohort study.

SETTING

Territory-wide electronic health record database of the Hong Kong Hospital Authority.

PARTICIPANTS

Patients newly diagnosed with AF between 2010 and 2017 who received a new prescription for warfarin or a direct oral anticoagulant (DOAC) (apixaban, dabigatran, or rivaroxaban). Follow-up ended on 31 December 2018.

MEASUREMENTS

Osteoporotic hip and vertebral fractures in anticoagulant users were compared using propensity score-weighted cumulative incidence differences (CIDs).

RESULTS

There were 23 515 patients identified (3241 apixaban users, 6867 dabigatran users, 3866 rivaroxaban users, and 9541 warfarin users). Overall mean age was 74.4 years (SD, 10.8), ranging from 73.1 years (warfarin) to 77.9 years (apixaban). Over a median follow-up of 423 days, 401 fractures were identified (crude event number [weighted rate per 100 patient-years]: apixaban, 53 [0.82]; dabigatran, 95 [0.76]; rivaroxaban, 57 [0.67]; and warfarin, 196 [1.11]). After 24-month follow-up, DOAC use was associated with a lower risk for fracture than warfarin use (apixaban CID, -0.88% [95% CI, -1.66% to -0.21%]; dabigatran CID, -0.81% [CI, -1.34% to -0.23%]; and rivaroxaban CID, -1.13% [CI, -1.67% to -0.53%]). No differences were seen in all head-to-head comparisons between DOACs at 24 months (apixaban vs. dabigatran CID, -0.06% [CI, -0.69% to 0.49%]; rivaroxaban vs. dabigatran CID, -0.32% [CI, -0.84% to 0.18%]; and rivaroxaban vs. apixaban CID, -0.25% [CI, -0.86% to 0.40%]).

LIMITATION

Residual confounding is possible.

CONCLUSION

Among patients with AF, DOAC use may result in a lower risk for osteoporotic fracture compared with warfarin use. Fracture risk does not seem to be altered by the choice of DOAC. These findings may help inform the benefit-risk assessment when choosing between anticoagulants.

PRIMARY FUNDING SOURCE

The University of Hong Kong and University College London Strategic Partnership Fund.

Systematic DOACs oral anticoagulation in patients with atrial fibrillation and chronic kidney disease: the nephrologist's perspective

Atrial fibrillation (AF) is highly prevalent among patients with chronic kidney disease (CKD), and also associated with unfavorable outcome. Anticoagulant therapy is the mainstep of management in such patients, aimed at reducing the high risk of systemic thromboembolism and especially of ischemic stroke, which is reportedly associated with increased mortality in CKD patients. Even though new direct oral anticoagulant agents (DOACs) proved to be effective in patients with non valvular chronic AF, and are therefore recommended by recent guidelines for their treatment, warfarin is currently used in more than one-half of subjects needing oral anticoagulation, and only 30% of them are converted from a vitamin K antagonist- to a DOAC-based regimen. The main reason for not prescribing DOACs is often a reduction in renal function, even if mild. Aim of this review was therefore to evaluate the impact of DOAC therapy in the setting of CKD, from a nephrological perspective, by comparing available evidence on the role of DOACs in patients with CKD and AF with that emerging from traditional warfarin-based therapy. Both the pathogenesis of AF in CKD, and available findings of renal, cardiovascular and bone effects of DOACs in CKD are discussed, leading to the conclusion that DOAC therapy should be considered as the first line therapy for non valvular AF in patients with mild and moderate reduction of renal function, and could also be adopted for patients with severe CKD not on hemodialysis treatment, whereas there is insufficient evidence for ESRD patients on dialysis.

Risk of Osteoporosis in Patients With Atrial Fibrillation Using Non-Vitamin K Antagonist Oral Anticoagulants or Warfarin

Background Warfarin, a vitamin K antagonist, has been shown to affect bone mineral density and cause osteoporosis. However, studies investigating the relationship between non-vitamin K antagonist oral anticoagulants (NOACs) and osteoporosis are limited. We thus compared the risk of osteoporosis in patients with atrial fibrillation treated with either NOACs or warfarin. Methods and Results This nationwide, retrospective cohort study used Taiwan's National Health Insurance Research Database. All adult patients in Taiwan who were newly diagnosed with atrial fibrillation and treated with NOACs or warfarin between January 2012 and December 2015 were included and classified into their respective cohorts. Patients who received NOACs were subcategorized into the rivaroxaban, dabigatran, and apixaban subgroups. Propensity score matching was performed for each head-to-head comparison. Adjusted hazard ratios (aHRs) for the risk of osteoporosis were calculated using Cox proportional hazards regression models, with adjustment for confounders. Overall, 17 008 patients were included, with 8504 in each cohort. NOACs were associated with a lower osteoporosis risk than warfarin (aHR=0.82; 95% CI=0.68-0.97). A subgroup effect of treatment duration was identified (namely, the lower osteoporosis risk with NOAC compared with warfarin became stronger in those with longer treatment duration [P for interaction <0.001]). Furthermore, significantly lower risks of osteoporosis were observed in the rivaroxaban (aHR=0.68; 95% CI=0.55-0.83) and apixaban (aHR=0.38; 95% CI=0.22-0.66) subgroups, but not in the dabigatran subgroup (aHR=1.04; 95% CI=0.85-1.27). Conclusions Compared with warfarin, rivaroxaban and apixaban were associated with a significantly lower risk of osteoporosis in patients with atrial fibrillation.

Association between oral anticoagulants and osteoporosis: Real-world data mining using a multi-methodological approach

Introduction: Warfarin and direct oral anticoagulants (DOACs) have been widely used in antithrombotic therapy. Although warfarin use has been suspected to be associated with osteoporosis risk, several studies have shown otherwise. Conversely, a few reports have found an association between DOACs and osteoporosis. This study therefore clarifies the association between oral anticoagulants and osteoporosis by analyzing real-world data using different methodologies, algorithms, and databases. Methods: Real-world data from the US Food and Drug Administration Adverse Event Reporting System (FAERS; 2004-2016) and Japanese administrative claims database (2005-2017; JMDC Inc., Tokyo) were used. Reporting odds ratio (ROR) and information component (IC) were calculated through disproportionality analysis (DPA) using reports recorded in the FAERS. Sequence symmetry analysis (SSA) was employed to calculate the adjusted sequence ratio (SR) using the JMDC Claims Database. For the adjusted SR and ROR, a significant signal was detected when the lower limit of the two-sided 95% confidence interval (CI) was more than 1. For the IC, a significant signal was detected when the lower limit of the 95% CI was more than 0. Results: DPA for warfarin found significant signals for osteoporosis in ROR (1.43, 95% CI: 1.32-1.54) and IC (0.50, 95% CI: 0.39-0.61). SSA showed a significant association between warfarin use and osteoporosis or bisphosphonate use. Moreover, a significant association was observed in males and females, albeit only for warfarin. Conclusion: Multi-methodological data mining revealed that warfarin use, not DOACs, is significantly associated with osteoporosis regardless of sex difference.

Vitamin K and Bone Health: A Review on the Effects of Vitamin K Deficiency and Supplementation and the Effect of Non-Vitamin K Antagonist Oral Anticoagulants on Different Bone Parameters

Although known for its importance in the coagulation cascade, vitamin K has other functions. It is an essential vitamin for bone health, taking part in the carboxylation of many bone-related proteins, regulating genetic transcription of osteoblastic markers, and regulating bone reabsorption. Vitamin K deficiency is not uncommon, as deposits are scarce and dependent upon dietary supplementation and absorption. Vitamin K antagonist oral anticoagulants, which are prescribed to many patients, also induce vitamin K deficiency. Most studies find that low serum K1 concentrations, high levels of undercarboxylated osteocalcin (ucOC), and low dietary intake of both K1 and K2 are associated with a higher risk of fracture and lower BMD. Studies exploring the relationship between vitamin K supplementation and fracture risk also find that the risk of fracture is reduced with supplements, but high quality studies designed to evaluate fracture as its primary endpoint are needed. The reduction in risk of fracture with the use of non-vitamin K antagonist oral anticoagulants instead of warfarin is also of interest although once again, the available evidence offers disparate results. The scarce and limited evidence, including low quality studies reaching disparate conclusions, makes it impossible to extract solid conclusions on this topic, especially concerning the use of vitamin K supplements.

Inhibitory effects of dabigatran etexilate, a direct thrombin inhibitor, on osteoclasts and osteoblasts

INTRODUCTION

Anticoagulants are widely used in orthopedic surgery to decrease the risk of deep vein thrombosis. While significant bone impairment is induced by long-term heparin therapy, little is known about the effects of direct oral anticoagulants (DOACs). Herein, we investigated the effects of dabigatran etexilate (Pradaxa®), a DOAC inhibitor of thrombin, on bone cells using in vitro and ex vivo cell culture models.

MATERIALS AND METHODS

Osteoblasts and osteoclasts exposed to different concentrations of dabigatran etexilate and untreated cells were assayed for cell differentiation and activity. Favorable osteogenic conditions for osteoblasts were tested using titanium with nanotopography (Ti-Nano). In addition, mice treated with a dabigatran etexilate solution had bone marrow cells analyzed for the ability to generate osteoclasts.

RESULTS

Dabigatran etexilate at concentrations of 1 μg/mL and 2 μg/mL did not impact osteoclast or osteoblast viability. The drug inhibited osteoclast differentiation and activity as observed by the reduction of TRAP+ cells, resorption pits and gene and protein expression of cathepsin K. Consistently, osteoclasts from mice treated with dabigatran showed decreased area, resorptive activity, as well as gene and protein expression of cathepsin K. In osteoblast cultures, grown both on polystyrene and Ti-Nano, dabigatran etexilate reduced alkaline phosphatase (ALP) activity, matrix mineralization, gene expression of ALP and osteocalcin.

CONCLUSIONS

Dabigatran etexilate inhibited osteoclast differentiation in ex vivo and in vitro models in a dose-dependent manner. Moreover, the drug reduced osteoblast activity even under optimal osteogenic conditions. This study provides new evidence regarding the negative overall impact of DOACs on bone cells.

Non-vitamin K Antagonist Oral Anticoagulants vs. Warfarin at Risk of Fractures: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Warfarin is a traditional oral anticoagulant for preventing thrombotic events in patients with atrial fibrillation (AF) and venous thromboembolism. Along with the widespread clinical use, the potential association between warfarin use and fracture risk have been addressed gradually. Non-vitamin K antagonist oral anticoagulants (NOACs), targeting thrombin or Xa factor, have been recommended as an optimal alternative due to their favorable property of thromboembolism prophylaxis and reduced bleeding risk. However, evidence of the fracture risk with NOACs use is limited. Therefore, the present study investigated this issue by a meta-analysis. Medline, Embase, Cochrane Library and the ClinicalTrials.gov Website were searched for randomized controlled trials (RCTs) that reported the fracture data of NOACs and warfarin. The primacy outcome was a composite of any fracture. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random- or fixed-effects models according to between-study heterogeneity. Heterogeneity was assessed through I² test and Q statistic, and the number of patients needed to treat (NNT) was calculated based on fracture incidence. Subgroup analyses were conducted according to individual NOACs, indications, and duration of follow up. Finally, 12 RCTs involving 89,549 patients were included, among which 44,816 (50%) receiving NOACs and 44,733 (50%) receiving warfarin. Overall, 1,139 (1.3%) patients including 515 NOACs users (1.1%) and 624 warfarin users (1.4%) developed fracture. Risk of fracture was significantly lower in NOACs compared to warfarin (RR: 0.82, 95%CI: 0.73–0.93, P = 0.001), with a NNT of 333. No significantly decreased risk was detected according to fracture sites. Subgroup analysis confirmed that the estimate of decreased fracture risk was derived mainly from AF patients receiving long-term anticoagulation treatment. The meta-regression did not detect any potential confounding on fracture risk. No heterogeneity between the studies (I² = 15.0%) and no publication bias was identified. In conclusion, the use of NOACs was associated with a lower risk of fracture compared to warfarin, but with a relatively low absolute risk reduction. Therefore, screening for the fracture risk should be considered before initiating anticoagulation treatment. For patients who are at high risk of fracture or expected long-term treatment of anticoagulation, NOACs may represent a preferable alternative to warfarin.

GIT1 gene deletion delays chondrocyte differentiation and healing of tibial plateau fracture through suppressing proliferation and apoptosis of chondrocyte

Background

Although tibial plateau fracture is an uncommon injury, its regulation is challenging and there are some influencing factors, including the effects of severe bone displacement, depression and cancellous bone cartilage, and inevitable cartilage damage. And GIT1 plays an important role in bone mass and 78 osteoblast cell migration.

Methods

The study used 72 C57/BL6 mice. A tibial plateau fracture model was established by using mice with the same number of GIT1 gene deletions (the experimental group) and their wild-type littermates (the control group). Joint and bone callus recovery were evaluated by X-ray and CT thin layer scans. Micro CT assay and histomorphometry were conducted in order to evaluate the volume of newly formed blood vessels. Type II collagen expression in tibial tissues after tibial plateau fracture were detected by immunohistochemistry after 7, 14 and 21 days. The number of proliferating cell nuclear antigen (PCNA) positive cells after tibial plateau fracture was tested by immunohistochemistry after 14 and 21 days. The terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining was conducted after 14 and 21 days in order to test chondrocyte apoptosis in tibial tissues after tibial plateau fracture.

Results

The GIT1 gene deletion group mice spent less time on the rotating rod than the control group mice (P < 0.05). Compared with the control group, postoperative recovery was retarded, because GIT1 gene deletion slowed down neovascularization after tibial plateau fracture (P < 0.05). Compared with the control group, mouse type II collagen expression significantly decreased in the GIT1 gene deletion group, and the proportion of PCNA positive cells significantly decreased (P < 0.05). The TUNEL results indicate that GIT1 gene deletion led to reduced chondrocyte apoptosis.

Conclusion

GIT1 gene deletion can inhibit chondrocyte proliferation and apoptosis during the recovery of tibial plateau fracture, so as to delay chondrocyte differentiation and tibial plateau fracture healing.

The effect of a new oral anticoagulant (Rivaroxaban) on implants pull-out strength. An experimental study in rats

OBJECTIVES

Thromboprophylaxis reduces the risk of surgery related deep venous thrombosis and pulmonary embolism. The classical anticoagulants (heparin and LWMH) were associated with systemic osteoporosis, poor bone healing and materials' osseointegration. There is a lack of data concerning the effect of the new orally administered anticoagulants on osseointegration. The aim of this study is to investigate the possible effect of rivaroxaban, a direct anti-Xa factor, on osseointegration.

METHODS

Twenty eight white, male, Wistar rats were divided into two groups: Group A, study group (n=14) and group B, control group (n=14). In all animals under general anesthesia one screw was inserted on the right tibia. For twenty eight days the animals of group A received intraperitoneal rivaroxaban injections 5mgr/kgr every day. The animals of group B received intraperitoneal equal amount of normal saline injections. At the end of the four weeks all animals were sacrificed and their right tibias were excised and underwent the pull-out test.

RESULTS

The mean values of pull-out test were 92,10±19,12N for the control group and 95,46±21,02N for the study group. The statistical analysis using t-test showed no significant difference (p=0,665) for the pull-out test.

CONCLUSIONS

These results indicate that Rivaroxaban hasn't got any deleterious effect on the osseointegration of implants on rats.

Does Anticoagulant Medication Alter Fracture-Healing? A Morphological and Biomechanical Evaluation of the Possible Effects of Rivaroxaban and Enoxaparin Using a Rat Closed Fracture Model

Low molecular weight heparin (LMWH) is routinely used to prevent thromboembolism in orthopaedic surgery, especially in the treatment of fractures or after joint-replacement. Impairment of fracture-healing due to increased bone-desorption, delayed remodelling and lower calcification caused by direct osteoclast stimulation is a well-known side effect of unfractioned heparin. However, the effect of LMWH is unclear and controversial. Recent studies strongly suggest impairment of bone-healing in-vitro and in animal models, characterized by a significant decrease in volume and quality of new-formed callus. Since October 2008, Rivaroxaban (Xarelto) is available for prophylactic use in elective knee- and hip-arthroplasty. Recently, some evidence has been found indicating an in vitro dose independent reduction of osteoblast function after Rivaroxaban treatment. In this study, the possible influence of Rivaroxaban and Enoxaparin on bone-healing in vivo was studied using a standardized, closed rodent fracture-model. 70 male Wistar-rats were randomized to Rivaroxaban, Enoxaparin or control groups. After pinning the right femur, a closed, transverse fracture was produced. 21 days later, the animals were sacrificed and both femora harvested. Analysis was done by biomechanical testing (three-point bending) and micro CT. Both investigated substances showed histomorphometric alterations of the newly formed callus assessed by micro CT analysis. In detail the bone (callus) volume was enhanced (sign. for Rivaroxaban) and the density reduced. The bone mineral content was enhanced accordingly (sign. for Rivaroxaban). Trabecular thickness was reduced (sign. for Rivaroxaban). Furthermore, both drugs showed significant enlarged bone (callus) surface and degree of anisotropy. In contrast, the biomechanical properties of the treated bones were equal to controls. To summarize, the morphological alterations of the fracture-callus did not result in functionally relevant deficits.

Fracture healing in the elderly: A review

Older patients are commonly at a higher risk of experiencing a bone fracture. Complications during fracture healing, including delayed union and non-union, can arise as a result of a multitude of patient and treatment factors. This review describes those factors which contribute to a greater risk of delayed union and non-union with particular reference to the elderly population and discusses therapies that may enhance the fracture healing process in the hope of reducing the incidence of delayed union and non-union. Increasing age does seem to increase the risk of delayed union or non-union. In addition, smoking and the treatment of post-fracture pain with non-steroidal anti-inflammatory drugs (NSAIDs) put the patient at the greatest risk, while ultrasound therapy appears to be a non-invasive, effective treatment option to reduce the risk of delayed union or non-union. The use of growth factors and of stem cells and the role of surgery are also discussed.

Effects of thromboprophylaxis on mesenchymal stromal cells during osteogenic differentiation: an in-vitro study comparing enoxaparin with rivaroxaban

Background

Low-molecular-weight heparins (e.g. Enoxaparin) are widely used to prevent venous thromboembolism after orthopaedic surgery, but there are reports about serious side effects including reduction in bone density and strength. In recent years new oral antithrombotic drugs (e.g. direct Factor Xa-inhibitor, Rivaroxaban) have been used to prevent venous thromboembolism. However, there is lack of information on the effects of these new drugs on human mesenchymal stromal cells during osteogenic differentiation and, therefore, effects during postoperative bone healing.

Methods

We evaluated the effects of Rivaroxaban and Enoxaparin on the proliferation, mRNA and surface receptor expression as well as differentiation capacity of primary human mesenchymal stromal cells during their osteogenic differentiation.

Results

Enoxaparin, but not Rivaroxaban treatment significantly increased human mesenchymal stromal cell (hMSC) proliferation during the first week of osteogenic differentiation while suppressing osteogenic marker genes, surface receptor expression and calcification.

Conclusions

This is the first paper to demonstrate that Rivaroxaban had no significant influence on hMSC differentiation towards the osteogenic lineage, indicating a less affected bone healing process compared with Enoxaparin in vitro. Based on these findings Rivaroxaban seems to be superior to Enoxaparin in early stages of bone healing in vitro.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-0966-2) contains supplementary material, which is available to authorized users.

Comparison of the effects of heparin and the direct factor Xa inhibitor, rivaroxaban, on bone microstructure and metabolism in adult rats

AIM

Deep venous thrombosis is a significant complication following surgery, and is associated with high morbidity and mortality in adults. The direct factor Xa inhibitor, rivaroxaban, is used to prevent venous thromboembolism in patients suffering from trauma and joint arthroplasty. The present study compared the effects of rivaroxaban and heparin on bone microstructure and metabolism in adult rats.

MATERIALS AND METHODS

Twenty-four Wistar rats were divided into sham, rivaroxaban and heparin groups. Rivaroxaban (1.5 mg·kg(-1)·d(-1)) and heparin (2 IU·g(-1)·d(-1)) were administered for 4 weeks. To assess changes in bone metabolism, serum calcium and phosphorus levels, and bone formation and resorption markers were examined. Micro-CT analysis was used to examine the microstructure of both trabecular and cortical bone. Dual energy X-ray absorptiometry was employed to detect bone mineral density (BMD).

RESULTS

Serum phosphorus levels were significantly lower in both rivaroxaban (1.33 ± 0.07 mmol/L) and heparin (1.33 ± 0.21 mmol/L) rats than in sham rats (1.71 ± 0.14 mmol/L). Activity and levels of bone formation markers, bone-specific alkaline phosphatase (BAP) and type I procollagen N-terminal pro-peptide (PINP), were 32.4 and 38.2% lower in heparin-treated rats than in sham rats. Bone resorption markers, pyridinoline (PYD) and deoxypyridinoline (DPD), were 20.1 and 34.3% higher in heparin-treated rats than in sham rats, respectively. By contrast, rivaroxaban only resulted in a decrease PINP levels. Bone volume fraction (BV/TV) decreased by 23.5 and 20.5% from those in sham rats, while trabecular separation (Tb.Sp) increased by 28.2 and 16.3% in trabecular bone of heparin- and rivaroxaban-treated rats, [corrected] respectively. Moreover, the microstructure of cortical bone and BMD were negatively affected by heparin but not by rivaroxaban.

CONCLUSION

Rivaroxaban leads to fewer adverse effects on bone microstructure than heparin.