Factor V Leiden (G1691A) and Prothrombin Gene G20210A Mutations as Potential Risk Factors for Venous Thromboembolism after Total Hip or Total Knee Replacement Surgery

Total shoulder arthroplasty in patients with factor V Leiden

BACKGROUND

Anatomic and reverse total shoulder arthroplasty (TSA) are effective treatment options for end-stage glenohumeral osteoarthritis. However, consideration for pre-existing conditions must be taken into account. Factor V Leiden (FVL), the most common inherited thrombophilia, is one such condition that predisposes to a prothrombotic state and may affect perioperative and longer-term outcomes following TSA.

METHODS

Adult patients undergoing primary TSA for osteoarthritis indication were identified in the 2010 through October 2021 PearlDiver M157 database. Patients with or without FVL were matched at a 1:4 ratio based on age, sex, and Elixhauser Comorbidity Index. Ninety-day adverse events and 5-year revision rates were assessed and compared with multivariable logistic regression and rank-log tests, respectively. Finally, the relative use and bleeding/clotting outcomes were assessed based on venous thromboembolic (VTE) prophylactic agents used, with categories defined as (1) warfarin, heparin, or direct oral anticoagulant (DOAC) or (2) aspirin/no prescription found.

RESULTS

Of 104,258 TSA patients, FVL was identified for 283 (0.27%). Based on matching, 1081 patients without FVL and 272 patients with FVL were selected. Multivariable analyses demonstrated that those with FVL displayed independently greater odds ratios (ORs) of deep vein thrombosis (DVT, OR = 9.50, P < .0001), pulmonary embolism (PE, OR = 10.10, P < .0001), and pneumonia (OR = 2.43, P = .0019). Further, these events contributed to the increased odds of aggregated minor (OR = 1.95, P = .0001), serious (OR = 6.38, P < .0001), and all (OR = 3.51, P < .0001) adverse events. All other individual 90-day adverse events, as well as 5-year revision rates, were not different between the study groups. When compared to matched patients without FVL on the same anticoagulant agents, FVL patients on warfarin, heparin, or DOAC agents demonstrated lesser odds of 90-day DVT and PE (OR = 4.25, P < .0001, and OR = 2.54, P = .0065) than those on aspirin/no prescription found (OR = 7.64 and OR = 21.95, P < .0001 for both). Interestingly, those on VTE prophylactic agents were not at greater odds of bleeding complications (hematoma or transfusion).

DISCUSSION AND CONCLUSIONS

TSA patients with FVL present a difficult challenge to shoulder reconstruction surgeons. The current study highlights the strong risk of VTE that was reduced but still significantly elevated for those with stronger classes of VTE chemoprophylaxis. Acknowledging this risk is important for surgical planning and patient counseling, but also noted was the reassurance of similar 5-year revision rates for those with vs. without FVL.

Complications of Factor V Leiden in Adults Undergoing Noncardiac Surgical Procedures: A Systematic Review

Factor V Leiden is the commonest hereditary prothrombotic allele, affecting 1% to 5% of the world's population. The objective of this study was to characterize the perioperative and postoperative outcomes of patients with Factor V Leiden compared to patients without a diagnosis of hereditary thrombophilia. This was a focused systematic review of studies including adult (>18 years) patients with Factor V Leiden (heterozygous or homozygous) undergoing noncardiac surgery. Included studies were either randomized controlled trials or observational. The primary clinical outcomes of interest were thromboembolic events occurring from the perioperative period up to 1 year postoperatively, defined as deep venous thrombosis, pulmonary embolism, or other clinically significant thrombosis occurring during or after a surgical procedure. Secondary outcomes included cerebrovascular events, cardiac events, death, transplant-related outcomes, and surgery-specific morbidity. Pediatric and obstetrical patients were excluded, as were case reports and case series. Databases searched included MEDLINE and EMBASE from inception until August 2021. Study bias was assessed through the CLARITY (Collaboration of McMaster University researchers) Risk of Bias tools, and heterogeneity through analysis of study design and end points, as well as the I 2 statistic with its confidence interval and the Q statistic. A total of 5275 potentially relevant studies were identified, with 115 having full text assessed for eligibility and 32 included in the systematic review. On the whole, the literature suggests that patients with Factor V Leiden have an increased risk of perioperative and postoperative thromboembolic events compared to patients without the diagnosis. Increased risk was also seen in relation to surgery-specific morbidity and transplant-related outcomes, particularly arterial thrombotic events. The literature did not support an increased risk for mortality, cerebrovascular, or cardiac complications. Limitations of the data include predisposition toward bias due in many study designs and small sample sizes across the majority of published studies. Variable outcome definitions and durations of patient follow-up across different surgical procedures resulted in high study heterogeneity precluding the effective use of meta-analysis. Factor V Leiden status may confer additional risk for surgery-related adverse outcomes. Large, adequately powered studies are required to accurately estimate the degree of this risk by zygosity.

Hormone replacement therapy in women with history of thrombosis or a thrombophilia

Findings from the Women's Health Initiative (WHI) randomised placebo-controlled trial (RCT) were published at the beginning of this century. They suggested that hormone replacement therapy (HRT) use increased the risk of cardiovascular disease and venous thromboembolism including pulmonary embolism and deep vein thrombosis The findings led to a decline in HRT prescriptions and negative publicity about the use of HRT for women with significant menopausal symptoms. Subsequent studies have shown that the risk of thrombosis with HRT relates to whether estrogen is combined with a progestogen and the route of administration of estrogen. In healthy women with no background medical problems, transdermal hormone replacement is not associated with an increased risk of thrombosis. However, much less is known about the safety of various HRT preparations in women with a high background risk of thrombosis. These cases can often be challenging for clinicians with uncertainties around testing for thrombophilia, use of anticoagulation and striking a balance between the risks and benefits of prescribing HRT. This article will review the mechanism of thrombosis with differing types of HRT and present the evidence from the relevant trials. The article will also present the evidence that specifically relates to women with a personal history of thrombosis or thrombophilia (heritable and acquired) to enable clinicians to better individualise the risk assessment for each woman requesting HRT and understand the role of thrombophilia screening or concomitant anticoagulation in such situations.

Tranexamic acid is safe and effective in patients with heterozygous factor V Leiden mutation during total joint arthroplasty

INTRODUCTION

Patients with an inherent hypercoagulable state are at a higher risk of venous thromboembolism (VTE) following total joint arthroplasty (TJA). Further administration of tranexamic acid (TXA) during TJA may increase the risk of VTE in these high-risk patients. There is no study that specifically analyzes the safety and efficacy of TXA during TJA in patients with factor V Leiden (FVL) mutation; therefore, the purpose of this study was to evaluate the safety and efficacy of TXA use on the risk of VTE and bleeding in patients carrying FVL mutation.

MATERIALS AND METHODS

A total of 42 patients with FVL mutation (22 hips, 20 knees) and 40 control patients (20 hips, 20 knees) who underwent TJA were retrospectively reviewed. All patients received 1 g TXA intravenously 15 min before the skin incision and 2 g of TXA was administered locally at the surgical site as a periarticular injection. Pharmacological thromboprophylaxis (low-molecular-weight heparin) was administered to all patients. Estimated blood loss and in-hospital thromboembolic complications were compared between the groups.

RESULTS

In both total knee arthroplasty (TKA) and total hip arthroplasty (THA) patients, there was no significant difference in the amount of estimated blood loss among the groups (p = 0.980, and p = 0963, respectively). None of the patients in the THA group received a blood transfusion. The transfusion rate was similar in the TKA group (p = 0.756, one patient in each group). No VTE, myocardial infarction, or any other complications related to TXA use were observed in any of the patients.

CONCLUSIONS

The combined local and systemic administration of TXA could be safely used in patients with heterozygous FVL mutation receiving pharmacological thromboprophylaxis during TJA without increasing the risk of VTE.

Familial Thrombophilia Is Associated With Primary Multifocal Osteonecrosis: A Case-Control Study of 40 Patients

To characterize pathoetiologic associations of heritable thrombophilia-hypofibrinolysis with idiopathic (primary) multifocal osteonecrosis (ON) (≥3 ON anatomic sites), we prospectively studied 28 women and 12 men with primary multifocal ON compared with 27 women and 24 men with primary nonmultifocal ON (<3 sites) and 110 healthy controls without ON. The 40 cases with primary multifocal ON differed from controls for 3 familial thrombophilias: Factor V Leiden heterozygosity (6 of 40 [15%] vs 2 of 109 [2%], P=.002), G20210A prothrombin gene heterozygosity (6 of 40 [15%] vs 3 of 110 [3%], P=.011), and high (>150%) Factor VIII (8 of 40 [20%] vs 7 of 103 [7%], P=.031). These case-control familial coagulation differences paralleled those in 51 concurrently evaluated cases with primary nonmulti-focal ON, 7 of 51 (14%) of whom had Factor V Leiden heterozygosity vs 2% of controls (P=.005) and 14 of 44 (32%) of whom had high Factor VIII vs 7 of 103 (7%) of controls (P=.0002). Recognition of familial thrombophilia as a common pathoetiology of primary multifocal ON provides an opportunity for early anticoagulation (before joint collapse), allowing both prophylaxis and therapy aimed at relieving pain and slowing or stopping progression of the disease to joint collapse. [Orthopedics. 202X;XX(X):xx-xx.].

Integrative analyses of genes about venous thromboembolism: An umbrella review of systematic reviews and meta-analyses

BACKGROUND

In recent years, many studies have found possible links between gene polymorphisms and venous thromboembolism (VTE). By identifying genetic risk factors before facing environmental risk factors such as surgical interventions and COVID-19 vaccination, we could rapidly respond to the risk of VTE. The aim of this study was to perform an umbrella review of genetic variants related to VTE. Integrative gene analysis of VTE was performed to identify critical genetic variations.

METHODS

This study conducted an umbrella review of systematic reviews and meta-analyses. All included studies were selected from the PubMed/MEDLINE database. To select eligible studies, the following variables were extracted: first author name; effect size of each study genetic variant; year of publication; the number of studies included in each article; ethnicity, sample size, P values, and heterogeneity estimates. To assess cumulative evidence in genetic epidemiology about effects of gene polymorphisms on VTE, Human Genome Epidemiology Network's Venice criteria were used. Methodological quality assessment was conducted with JBI Critical Appraisal Checklist for Systematic Reviews and Research Syntheses.

RESULTS

Genes provided in the present study with genetic variants associated with VTE were FVL (G1691A), Prothrombin (G20210A), MTHFR (C677T, A1298C), PAI-1 (4G/5G), factor VII activating protease (1601G > A), and endothelial protein C receptor (g.6936A_G, c.4600A_G). Among them, variants in FVL, Prothrombin, MTHFR, and PAI-1 showed high significance. Particularly, variants in Prothrombin (G20210A), MTHFR (C677T), and PAI-1 (4G/5G) had more than 2 types of model significance.

CONCLUSION

The present study performed a systematic review of genetic variants associated with VTE. Our results could lead to a more comprehensive understanding of VTE etiology. These results could give a strategy of prediagnosis about evaluating individual risks of VTE who might be exposed to environmental risk factors.

Safety of DIEP Flap Reconstruction in Patients with Factor V Leiden: A Retrospective Cohort Study

Background:

Factor V Leiden (FVL) is the most common inherited thrombophilia in White people. Thrombotic complications resulting from free flap breast reconstruction in FVL patients have been studied to a limited degree. We evaluated whether patients heterozygous for a FVL mutation undergoing deep inferior epigastric perforator flap reconstruction had increased risk of micro- or macrovascular thrombotic complications compared with patients without a diagnosed thrombophilia.

Methods:

We performed a retrospective cohort study of deep inferior epigastric perforator flap reconstructions at Brigham and Women’s Hospital (1/2015–12/2020) comparing patients diagnosed as FVL heterozygotes compared with matched controls without a diagnosed thrombophilia. Patients were matched using coarsened exact matching algorithm based on clinical characteristics. The primary outcomes were micro- (return to OR for flap compromise, flap loss) and macrovascular (venous thromboembolism) complications.

Results:

A total of 506 patients (812 flaps) were included in this study. Eleven patients (17 flaps) were FVL heterozygotes. After matching, 10 patients (16 flaps) with FVL were matched to 55 patients (94 flaps). The return to OR for flap compromise was 0% in the FVL cohort compared with 5% (n = 5/94, 3/94 flaps lost, P = 1.00) in the matched controls (1.9%, n = 15/795 in unmatched controls, 0.6%, n = 5/795 loss rate). There were zero venous thromboembolism events among FVL patients compared with 2% of controls (n = 1/55).

Conclusions:

FVL heterozygosity did not increase the risk of micro- or macrovascular complications in patients undergoing deep inferior epigastric perforator flap breast reconstruction. This study supports the safety of microvascular reconstruction in this group of patients when appropriate venous thromboembolism prophylaxis is given.

Hypercoagulable Disorders in Orthopaedics: Etiology, Considerations, and Management

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Hypercoagulable disorders (HCDs) can be inherited or acquired. An HCD of either etiology increases the chance of venous thromboembolic events (VTEs).

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Patients with an HCD often have the condition discovered only after surgical complications.

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We recommend that patients with a concern for or a known HCD be referred to the appropriate hematological specialist for workup and treatment.

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Tourniquet use in the orthopaedic patient with an HCD is understudied and controversial. We recommend that tourniquets be avoided in the surgical management of patients with an HCD, if possible. When tourniquets are applied to patients with unknown HCD status, close follow-up and vigilant postoperative examinations should be undertaken.

Maxillofacial and oral surgery in patients with thrombophilia: safe territory for the oral surgeon? A single-center retrospective study

OBJECTIVE

The aim of this study was to analyze patients with thrombophilia who underwent oral and/or maxillofacial surgery at our center.

STUDY DESIGN

We performed a retrospective analysis of patients with hereditary or acquired thrombophilia who had undergone oral/maxillofacial surgery between January 1, 2000 and December 31, 2019. Data regarding demographic and patient characteristics, surgical treatment modalities, antithrombotic therapies, and complications were analyzed.

RESULTS

A total of 76 eligible patients (26 male, 50 female) were included in this study, with a mean follow-up period of 3.8 months (range, 0-51 months). The mean age at time of surgery was 44.7 ± 19.4 years. Seven different hereditary and acquired thrombophilia were identified: factor V Leiden (n = 31; 40.8%), prothrombin G20210A mutation (n = 5; 6.6%), protein C deficiency (n = 4; 5.3%), protein S deficiency (n = 11; 14.5%), antiphospholipid syndrome (n = 10; 13.2%), hyperhomocysteinemia (n = 8; 10.5%), and elevated factor VIII (n = 2; 2.6%). Complications occurred in 9 patients (11.8%) and included postoperative infections (n = 6; 7.9%) and postoperative bleeding (n = 3; 3.9%).

CONCLUSION

Our data suggest that oral and/or maxillofacial surgery in patients with a confirmed diagnosis of thrombophilia is not associated with a burden of thrombosis or high complication rates. Furthermore, we formulated a guideline for preoperative antithrombotic therapy for patients with thrombophilia undergoing oral and/or maxillofacial surgery.

Long-term Anticoagulation Prevents Progression of Stages I and II Primary Osteonecrosis of the Hip in Patients With Familial Thrombophilia

The authors prospectively assessed long-term anticoagulation outcomes (≥3 years) for 9 patients meeting 4 inclusion criteria: pretreatment Ficat stage I or II primary hip osteonecrosis (ON), factor V Leiden or prothrombin G20210A heterozygosity, no contraindication to anticoagulation, and 90-day participation in an initial enoxaparin 60 mg/d protocol. The primary endpoint was prevention of hip collapse (Ficat stage III or IV). The secondary endpoint was pain relief. After 90 days of enoxaparin 60 mg/d, anticoagulation was continued for 8 patients: 4 receiving warfarin (international normalized ratio targeted to 2 to 2.5; 11.5, 13, 14.5, and 21 years), 1 receiving enoxaparin 120 mg/d (11.5 years), and 3 receiving novel oral anticoagulants (5, 6, and 8 years). Radiographs were obtained before treatment; at 3 to 4, 6 to 8, and 12 to 14 months; and then annually. By selection, 8 patients had factor V Leiden heterozygosity and 1 had prothrombin G202010A heterozygosity. Of their 13 hips (Ficat I or II at entry), 12 remained Ficat I or II after 12±5 years (range, 5.5-21 years) of continuous anticoagulation and follow-up; 1 hip radiographically normalized. None of the 13 hips progressed to collapse (Ficat III or IV). Six patients became symptom free after the first 3 months of receiving enoxaparin, 1 after 6 months of anticoagulation, and 1 after 10 months of anticoagulation; all 8 patients remained symptom free with anticoagulation. Anticoagulation for primary hip ON before hip collapse in patients with familial thrombophilia may change the natural history of ON because most untreated patients with ON have joint collapse and total joint replacement within 2 years of original symptoms. [Orthopedics. 2020;43(4):e208-e214.].

Managing thromboembolic risk in patients with hereditary and acquired thrombophilias

While we are now able to diagnose inherited thrombophilias in a substantial number of patients with venous thromboembolism (VTE), the initial hope that their presence would inform recurrence risk and thus decisions on anticoagulation duration has largely been disappointing. Indeed, the presence or absence of transient provoking risk factors has proven to be the most important determinant of VTE recurrence risk. Thus, particular attention to transient acquired risk factors for VTE remains paramount, as they have generally been shown to carry more prognostic weight than inherited thrombophilias. The presence of other acquired risk factors may require additional management considerations, whether pertaining to anticoagulant choice, as in antiphospholipid antibody syndrome, or to addressing a new predisposing medical condition, as in malignancy. Antithrombin deficiency or the presence of ≥1 thrombophilic defect may be exceptions that can have a role in prognostication; however, as illustrated in this review through several case vignettes, interpretation and clinical application of the results of inherited thrombophilia testing is nuanced. We have chosen to focus on cases in which patients have been identified as having thrombophilic defects rather than the indications for undertaking testing in the first place or the extent of investigation. Management decisions in such cases ultimately hinge on individualized consideration of the benefits and risks of anticoagulation along with patient preference rather than on an algorithmic pathway based on thrombophilia status.

A Successful Collaborative Approach to the Perioperative Management After Hip Arthroscopy of a Patient with Heterozygous Prothrombin G20210A Mutation: A Case Report

CASE

We report on a patient with heterozygous prothrombin G20210A mutation (PTM) and a history of venous thromboembolism (VTE) after knee arthroscopy, who was undergoing hip arthroscopy. This common mutation has an overall prevalence of 2.0% and results in a 280% to 420% likelihood of thrombosis compared to patients without the mutation.

CONCLUSIONS

Hip arthroscopy is associated with a low risk of VTE with currently no guidelines for thromboprophylaxis. Patients should be managed in relation to their risk factors utilizing a collaborative, individualized approach. Treatment with short-term low-molecular-weight heparin resulted in no thromboembolism at 18-month follow-up for this patient with PTM.

Deep Vein Thrombosis Prophylaxis after Total Hip Arthroplasty in Asian Patients

In Western patient populations, the reported incidence of imaging-demonstrated deep vein thrombosis (DVT) after total hip arthroplasty (THA) is as high as 70% without prophylaxis. The reported rates of symptomatic pulmonary embolism (PE) after THA in recent studies range from 0.6% to 1.5%, and the risk of fatal PE ranges from 0.11% to 0.19% in the absence of prophylaxis. Predisposing factors to DVT in western patients include advanced age, previous venous insufficiency, osteoarthritis, obesity, hyperlipidemia, dietary and genetic factors. However, Asian patients who have undergone THA have a strikingly low prevalence of DVT and virtually no postoperative PE. Some authors suggest low clinical prothrombotic risk factors and the absence of some DVT-related genetic factors in Asian patient populations decrease the risk of DVT, PE or both. In Korea, the prevalence of DVT after THA without thromboprophylaxis have ranges from 6.8% to 43.8%, and asymptomatic PE have ranges from 0% to 12.9%; there have been only two reported cases of fatal PE. Deep-wound infections resulting from postoperative hematomas or prolonged wound drainage have been reported with routine thromboprophylaxis. The prevalence of DVT differs varies based on patient ethnicity. Guidelines for the use of thromboprophylaxis were altered and focus on the potential value of outcomes compared with possible complications (e.g., bleeding).

Postoperative Joint Replacement Complications in Swedish Patients With a Family History of Venous Thromboembolism

IMPORTANCE

The associations of a family history of venous thromboembolism (FH-VTE) with postoperative venous thromboembolism (VTE) and major bleeding after joint replacement surgical procedures are unknown.

OBJECTIVE

To determine the risk of VTE and major bleeding in patients after primary hip or knee replacement surgical procedures.

DESIGN, SETTING, AND PARTICIPANTS

Cohort study using nationwide population-based databases of Swedish patients without a history of VTE who underwent joint replacement surgical procedures. Patients who had primary hip or knee replacement surgical procedures between July 1, 2005, and August 31, 2012, were identified. Patients born after 1931 without previous VTE were identified in the Swedish Multi-Generation Register. Only individuals with at least 1 parent and 1 full sibling alive between 1964 and the date for the surgical procedure were included. The data analysis was performed from September 1, 2017, to June 15, 2018.

EXPOSURES

Family history of VTE in a parent and/or a full sibling before the date of the surgical procedure.

MAIN OUTCOMES AND MEASURES

Venous thromboembolism and major bleeding within 90 days of the surgical procedure.

RESULTS

Of 69 505 study participants, 37 989 (54.7%) were women, and the median (interquartile range) age at the date of discharge was 65 (59-70) years. A total of 803 of 69 505 (1.2%) patients experienced postoperative VTE and 1285 (1.8%) experienced major bleeding. The cumulative VTE risk for those with FH-VTE was 231 of 15 858 (1.5%) and for those without an FH-VTE was 572 of 53 647 (1.1%) (P < .001). The cumulative bleeding risk for those with FH-VTE was 261 of 15 858 (1.6%) and for those without an FH-VTE was 1024 of 53 647 (1.9%) (P = .03). There was an association of patients with an FH-VTE who had increased VTE risk (adjusted hazard ratio [HR], 1.36; 95% CI, 1.17-1.59) and reduced bleeding risk (adjusted HR, 0.84; 95% CI, 0.74-0.97). There was an interaction between time after discharge and FH-VTE regarding VTE and major bleeding. An FH-VTE was not associated with VTE after discharge during the first week (HR, 1.13; 95% CI, 0.86-1.49). After 7 days from discharge, FH-VTE was associated with VTE (HR, 1.49; 95% CI, 1.24-1.79). An FH-VTE reduced major bleeding risk during the first 7 days after discharge (HR, 0.78; 95% CI, 0.66-0.91) but not thereafter (HR, 1.10; 95% CI, 0.84-1.44). Postoperative VTE heritability (SE) was 20% (6%).

CONCLUSIONS AND RELEVANCE

Familial and most likely genetic factors appear to affect VTE and major bleeding risk following hip and knee replacement surgical procedures. Prolonged VTE prophylaxis might be beneficial in predisposed individuals. There may be a possible evolutionary advantage of prothrombotic genes protecting against traumatic bleeding.

The Prophylaxis of Venous Thromboembolism

BACKGROUND

Venous thromboembolism (VTE) is the third most common cardiovascular condition, after myocardial infarction and stroke. Prophylactic measures in accordance with current guidelines can significantly reduce the risk of VTE and the associated morbidity and mortality. Until now, the German interdisciplinary, evidence- and consensus-based (S3) clinical practice guideline on VTE prophylaxis was based on a complete review of all pertinent literature available in MEDLINE up to January 2008. More recent publications and drug approvals have made a thorough revision necessary.

METHODS

A systematic search was carried out in the MEDLINE and Embase databases for publications that appeared from 1 January 2008 to 7 August 2013. Updates of 5 national and international reference guidelines and 2 new Health Technology Assessment (HTA) reports were considered as well. A structured consensus-finding process was carried out with delegates from 27 scientific medical societies and from the Union of Medical Specialist Associations.

RESULTS

46 randomized controlled trials (RCTs) were included for critical appraisal. New findings led to re-evaluation of the value of compression stockings in combination with pharmacological prophylaxis (open recommendation), and suggest equal value of non-vitamin K antagonist oral anticoagulants (NOACs) and low molecular weight heparins (LMWH) or fondaparinux in elective hip and knee replacement (strong recommendation). For patients undergoing hip fracture surgery, we recommend LMWH or fondaparinux.

CONCLUSION

Further research is needed to assess the value of NOACs for pharmacological prophylaxis in orthopedic/trauma patients undergoing surgical procedures other than the ones mentioned above, and into the benefit and harm of new devices available for mechanical prophylaxis. The stringent implementation of basic measures such as early mobilization, movement exercises, and patient instruction is a key point to prevent venous thrombo - embolism.

Perioperative Management of Factor V Leiden and Pancreatic Adenocarcinoma

Background: Perioperative management of a patient with factor V Leiden has been infrequently reported with most studies focused in the orthopedic literature.

Case Presentation: We report a case of a 74-year-old woman who underwent a pylorus-preserving pancreaticoduodenectomy without immediate perioperative embolic or thrombotic phenomena and her management throughout her hospital course.

Conclusion: To the best of our knowledge, this is the first known report regarding factor V Leiden and surgical management of pancreatic ductal adenocarcinoma.

Ultrasound screening for deep venous thrombosis detection: a prospective evaluation of 200 plastic surgery outpatients

Background:

Our understanding of the pathophysiology of venous thromboembolism is largely based on the experience of orthopedic patients undergoing total joint replacement. Little is known regarding the natural history of venous thromboembolism in plastic surgery outpatients. Today, ultrasound screening, including compression and Doppler color flow imaging, represents the standard for detecting deep venous thromboses.

Methods:

Ultrasound screening was offered to 200 consecutive plastic surgery outpatients undergoing 205 operations. Patients were scanned before surgery, on the day after surgery, and approximately 1 week after surgery. No patient declined to participate (inclusion rate, 100%). Spontaneous breathing, Avoid gas, Face up, Extremities mobile anesthesia was used, with no chemoprophylaxis. Patient surveys were administered.

Results:

Six hundred ultrasound screening tests were performed. All scans performed the day after surgery were negative. Only one examination was positive, 8 days after a lipoabdominoplasty. Subsequent scans revealed complete resolution of the thrombosis with anticoagulation. Ninety percent of surveyed patients would choose to have ultrasound screening in the future.

Conclusions:

The natural history of thromboembolism in plastic surgery outpatients differs from orthopedic patients. The risk of a deep venous thrombosis in a patient treated with Spontaneous breathing, Avoid gas, Face up, Extremities mobile anesthesia is approximately 0.5%. Thromboses are unlikely to develop intraoperatively. In the single affected patient, the thrombosis was located distally, in a location that is less prone to embolism and highly susceptible to anticoagulation. Ultrasound screening is an effective and highly feasible method to identify affected patients for treatment.

Long term anticoagulation (4-16 years) stops progression of idiopathic hip osteonecrosis associated with familial thrombophilia

In 6 patients with familial thrombophilia (5 Factor V (FV) Leiden heterozygotes, 1 with resistance to activated protein C (RAPC)), we prospectively assessed whether continuous longterm (4–16 years) anticoagulation would prevent progression of idiopathic osteonecrosis (ON), ameliorate pain, and facilitate functional recovery. Four men and 2 women (9 hips, 8 Ficat stage II, 1 stage I) were anticoagulated with enoxaparin (60 mg/day) for 3 months and subsequently with Coumadin, Xarelto, or Pradaxa, warranted by ≥2 prior thrombotic events. Anticoagulation was continued for 4, 4, 9, 13, 13, and 16 years, with serial clinical and X-ray follow-up. On 4–16-years anticoagulation, 9 hips in the 6 patients (8 originally Ficat II, 1 Ficat I) remained unchanged, contrasted to untreated ON Ficat stage II, where 50%–80% of hips progress to collapse (Ficat stages III-IV) within 2 years after diagnosis. Within 3, 3, 3, 9, and 16 months after starting anticoagulation, 5 patients became pain-free and remained asymptomatic throughout follow-up; the 6th patient required Percocet for pain. There were no significant bleeding episodes. Long term (4–16 years) anticoagulation initiated in Ficat stages I-II of idiopathic hip ON in patients with FV-RAPC changes the natural history of ON, stopping progression, resolving pain, and restoring function.

Lower limb joint replacement in patients with a history of venous thromboembolism

Although patients with a history of venous thromboembolism (VTE) who undergo lower limb joint replacement are thought to be at high risk of further VTE, the actual rate of recurrence has not been reported. The purpose of this study was to identify the recurrence rate of VTE in patients who had undergone lower limb joint replacement, and to compare it with that of patients who had undergone a joint replacement without a history of VTE. From a pool of 6646 arthroplasty procedures (3344 TKR, 2907 THR, 243 revision THR, 152 revision TKR) in 5967 patients (68% female, mean age 67.7; 21 to 96) carried out between 2009 and 2011, we retrospectively identified 118 consecutive treatment episodes in 106 patients (65% female, mean age 70; 51 to 88,) who had suffered a previous VTE. Despite mechanical prophylaxis and anticoagulation with warfarin, we had four recurrences by three months (3.4% of 118) and six by one year (5.1% of 118). In comparison, in all our other joint replacements the rate of VTE was 0.54% (35/6528). The relative risk of a VTE by 90 days in patients who had undergone a joint replacement with a history of VTE compared with those with a joint replacement and no history of VTE was 6.3 (95% confidence interval, 2.3 to 17.5). There were five complications in the previous VTE group related to bleeding or over-anticoagulation.

Who are at risk for thromboembolism after arthroplasty? A systematic review and meta-analysis

BACKGROUND

Thromboembolism, including deep venous thrombosis and pulmonary embolism, is a grave threat to patients undergoing total joint replacement. Using a systematic review and meta-analysis we asked whether gene mutations or polymorphisms could be risk factors for thrombosis after arthroplasty.

METHODS

We performed a comprehensive search of Medline, PubMed, Embase, Cochrane databases, China National Knowledge Infrastructure (CNKI), and Google Scholar, and identified 19 studies detailing genetic investigations of patients with thromboembolism following joint replacement.

RESULTS

Our meta-analyses included 5149 patients who underwent arthroplasty surgery. Significant associations with venous thromboembolism were identified for factor G1691A (odds ratio (OR) 1.41, 95% confidence interval (CI) 1.03 - 1.94, p=0.03), prothrombin G20210A (OR 2.16, 95% CI, 1.27- 3.69, p=0.005), and MTHFR/C677T/TT (OR 2.36, 95% CI 1.03 - 5.42, p=0.04) in Caucasian populations. No significant gene mutation was identified in Asian populations.

CONCLUSION

This study suggests a way to identify patients scheduled for arthroplasty who are at higher risk of thrombosis, enabling individualized treatment.

The role of the factor V Leiden mutation in osteonecrosis of the hip

We examined the hypothesis that the factor V Leiden (FVL) and G20101A prothrombin gene mutations are commonly associated with hip osteonecrosis. We prospectively evaluated 244 consecutively referred adults with osteonecrosis (ON), 161 idiopathic and 83 secondary. Cases (n = 244) did not differ from 104 normal controls by race. Of the 244 patients, 23 (9.4%) were FVL heterozygotes versus 2 of 104 controls (1.9%), P = .013, risk ratio (RR) = 4.90, 95% confidence interval (CI) 1.18 to 20.4. Of the 161 patients with idiopathic ON, 15 (9.3%) were FVL heterozygotes versus 2 of 104 normal controls (1.9%), P = .017, RR = 4.84, 95% CI 1.13 to 20.8. Of the 83 patients with secondary ON, 8 (9.6%) FVL heterozygotes versus 2 of 104 normal controls (1.9%), P = .024, RR = 5.01, 95% CI 1.09 to 23.0. Prothrombin gene heterozygosity in normal controls (2.9%) did not differ from ON cases (3.4%), P = 1.0. The thrombophilic FVL mutation is commonly associated with and may be pathoetiologic for hip osteonecrosis.

Hematologic genetic testing in high-risk patients before knee arthroplasty: a pilot study

BACKGROUND

Patients with a personal or familial history of thromboembolism are considered at higher risk for thromboembolic disease after knee arthroplasty. While it remains unclear why some patients develop deep vein thrombosis (DVT) or pulmonary embolism (PE) despite similar operative procedures and the same prophylactic regimen, we presume one explanation would be genetic predisposition.

QUESTIONS/PURPOSES

We determined the frequency of 12 factors including antithrombin III activity, prothrombin gene mutations, and the presence of phospholipid antibodies in a high-risk patient cohort and compared those findings with the known prevalence in the population at large.

PATIENTS AND METHODS

Patients identified preoperatively as having a personal or familial history of DVT and/or PE were referred for hemostatic serum and genetic tests, including % antithrombin III activity (ATIII), protein C and protein S activities, APC resistance, Factor V gene (Leiden) mutations, prothrombin gene mutations, lupus anticoagulant antibody presence, cardiolipin antibody presence, phosphatidyl antibody presence, β2-glycoprotein antibody presence, and serum homocysteine and lipoprotein(a) levels The frequencies of varying abnormalities were identified and compared to the prevalence reported in the literature.

RESULTS

Forty-three of 1944 patients undergoing knee arthroplasty had a history of DVT or PE. Sixteen of 43 (37%) patients had an abnormality and eight of these (19%) had two or more abnormalities. The frequency of nine of the 12 tests appeared to be greater in this cohort than in the population at large.

CONCLUSIONS

Patients with a personal or familial history of DVT or PE appear to have a high frequency of hereditary prothrombotic abnormalities. Preoperative evaluation by a hematologist may be warranted in patients with a personal or familial history of DVT or PE as the postoperative anticoagulation protocols may be altered and identification of these abnormalities may affect a patient's risk for other disease states.

LEVEL OF EVIDENCE

Level IV, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Direct thrombin inhibitors versus vitamin K antagonists or low molecular weight heparins for prevention of venous thromboembolism following total hip or knee replacement

BACKGROUND

Patients who have undergone total hip or knee replacement (THR, TKR) have a high risk of developing venous thromboembolism (VTE) following surgery, despite appropriate anticoagulation with warfarin or low molecular weight heparin (LMWH). New anticoagulants are under investigation.

OBJECTIVES

To examine the efficacy and safety of prophylactic anticoagulation with direct thrombin inhibitors (DTIs) versus LMWH or vitamin K antagonists in the prevention of VTE in patients undergoing THR or TKR.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Disease Group searched their Specialized Register (last searched 12 March 2010) and CENTRAL (last searched 2010, Issue 2).

SELECTION CRITERIA

Randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Three reviewers independently assessed methodological quality and extracted data in pre-designed tables. The reported follow-up events were included

MAIN RESULTS

We included 14 studies included involving 21,642 patients evaluated for efficacy and 27,360 for safety. No difference was observed in major VTE in DTIs compared with LMWH in both types of operations (odds ratio (OR) 0.91; 95% confidence interval (CI) 0.69 to 1.19), with high heterogeneity (I(2) 71%). No difference was observed with warfarin (OR 0.85; 95% CI 0.63 to 1.15) in TKR, with no heterogeneity (I(2) 0%).More total bleeding events were observed in the DTI group (in ximelagatran and dabigatran but not in desirudin) in patients subjected to THR (OR 1.40; 95% CI 1.06, 1.85; I(2) 41%) compared with LMWH. No difference was observed with warfarin in TKR (OR 1.76; 95% CI 0.91 to 3.38; I(2) 0%). All-cause mortality was higher in the DTI group when the reported follow-up events were included (OR 2.06; 95% CI 1.10 to 3.87).Studies that initiated anticoagulation before surgery showed less VTE events; those that began anticoagulation after surgery showed more VTE events in comparison with LMWH. Therefore, the effect of the DTIs compared with LMWH appears to be influenced by the time of initiation of coagulation more than the effect of the drug itself.The results obtained from sensitivity analysis, did not differ from the analysed results; this strengthens the value of the results.

AUTHORS' CONCLUSIONS

Direct thrombin inhibitors are as effective in the prevention of major venous thromboembolism in THR or TKR as LMWH and vitamin K antagonists. However, they show higher mortality and cause more bleeding than LMWH. No severe hepatic complications were reported in the analysed studies. Use of ximelagatran is not recommended for VTE prevention in patients who have undergone orthopedic surgery. More studies are necessary regarding dabigatran.

Assessment of thrombotic risk factors predisposing to thromboembolic complications in prosthetic orthopedic surgery

BACKGROUND

Congenital thrombophilia is responsible for thromboembolic complications despite prolonged low-molecular-weight heparin (LMWH) prophylaxis following hip and knee endoprosthesis surgery.

METHODS

A series of 86 patients with hip or knee endoprosthesis surgery were assessed 1 year after operation. Antithrombin III, protein C, and protein S were determined, and the activated protein C sensitivity ratio was measured. We screened for the presence of lupus anticoagulant, factor V Leiden mutation, and polymorphism of prothrombin G20210A. The lower limb venous circulation was monitored by color Doppler ultrasonography. Pulmonary embolism (PE) was diagnosed using ventilation and perfusion scintigraphy.

RESULTS

In all, 33 patients had thromboembolic complications, 18 with thrombophilia (7 with combined form). Of the 53 patients without complications 12 had thrombophilia (2 with combined form). The differences were statistically significant. The risk score, the prevalence of FV Leiden and prothrombin G20210A mutations, and lupus anticoagulant were also significantly higher in the symptomatic group. Deep vein thrombosis (DVT) developed preoperatively in 15 patients; DVT and PE in 4 patients; thrombophilia was diagnosed in 53% and 75% of these cases. In all, 17 patients had postoperative thromboembolic complications: DVT developed in nine and PE in one patient (all with thrombophilia); DVT + PE developed in seven patients (all but one had thrombophilia).

CONCLUSIONS

Significant differences were found in the incidence (P < or = 0.01) of thrombophilia and the risk score (P < or = 0.02) between symptomatic and asymptomatic patients. We recommend preoperative thrombophilia screening for patients with a history or familial prevalence of thromboembolism and/or with a high risk score (> or =15). In cases of thrombophilia, the form and duration of anticoagulant treatment must be decided individually.

Case reports: heritable thrombophilia associated with deep venous thrombosis after shoulder arthroscopy

Thromboembolic complications after shoulder arthroscopy are rare and their cause has not been well determined. Heritable thrombophilia has been studied in relation to numerous clinical conditions, and it has been associated with thromboembolic complications after some orthopaedic surgeries, especially after total hip or knee arthroplasty. We report three patients who had deep vein thrombosis develop after shoulder arthroscopy. All three tested positive for heritable thrombophilia, a condition undetected until this complication occurred. This report highlights the possibility that unrecognized coagulation disorders might seriously influence the clinical outcome of minimally invasive surgery. We suggest heritable thrombophilia is a possible risk factor for or etiology of deep vein thrombosis after shoulder arthroscopy.

Correlation between single nucleotide polymorphism of prothrombin gene G20210 and deep vein thrombosis after total joint replacement in Chinese patients

OBJECT

To evaluate the correlation between prothrombin gene G20210A mutation and deep vein thrombosis after total joint replacement through detecting distribution frequency of single nucleotide polymorphism of the gene in patients undergoing total joint replacement.

METHOD

PCR and direct sequencing of DNA are used to analyze the frequency of prothrombin gene G20210A mutation in 55 patients undergoing total joint replacement, and the relationship between the mutation and deep vein thrombosis after total joint replacement is evaluated.

RESULT

Morbidity of prothrombin gene G20210A mutation in 55 patients is 0, both in the DVT group and non-DVT group. There is no significant difference between the two groups (p > 0.05).

CONCLUSION

Mutation of prothrombin gene G20210A in Chinese patients is rare, and there is no correlation between the genetic mutation and deep vein thrombosis after total joint replacement.

Genetic polymorphisms in venous thrombosis and pulmonary embolism after total hip arthroplasty: a pilot study

Deep venous thrombosis (DVT) after major orthopaedic surgery is a substantial concern. We asked whether the single or combined presence of thrombophilic genetic polymorphisms might further increase the already high risk for venous thrombosis and pulmonary embolism (PE) after THA. We therefore compared the prevalence of factor V Leiden, prothrombin G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, and plasminogen activator inhibitor 4G/5G polymorphisms between 50 patients with symptomatic DVT within 3 weeks after elective THA and an asymptomatic control group of 85 patients. We found no major difference for the presence of a single mutation between the groups. Factor V Leiden and homozygous MTHFR C667T mutations were of borderline significance with odds ratios (95% confidence intervals) of 3.73 (0.89-15.63) and 2.93 (0.92-9.29), respectively. Patients with homozygous or combined heterozygous status of MTHFR C677T and A1298C mutation had a higher frequency of DVT after elective THA (odds ratio, 2.86; 95% confidence interval, 1.32-6.35) than those with wild-type. The presence of a single mutation may not further increase the already high risk for symptomatic DVT after THA, whereas combinations of mutations of distinct polymorphisms might be important. However, prospective studies with a larger number of patients are needed before we would recommend preoperative screening.

LEVEL OF EVIDENCE

Level III, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Prevention of symptomatic pulmonary embolism in patients undergoing total hip or knee arthroplasty

This clinical practice guideline is based on a systematic review of published studies on the management of adult patients undergoing total hip replacement (THR) or total knee replacement (TKR) aimed specifically at preventing symptomatic pulmonary embolism (PE). The guideline emphasizes the need to assess the patient's risk for both PE and postoperative bleeding. Mechanical prophylaxis and early mobilization are recommended for all patients. Chemoprophylactic agents were evaluated using a systematic literature review. Forty-two studies met eligibility criteria, of which 23 included patients who had TKR and 25 included patients who had THR. The following statements summarize the recommendations for chemoprophylaxis: Patients at standard risk of both PE and major bleeding should be considered for aspirin, low-molecular-weight heparin (LMWH), synthetic pentasaccharides, or warfarin with an international normalized ratio (INR) goal of < or =2.0. Patients at elevated (above standard) risk of PE and at standard risk of major bleeding should be considered for LMWH, synthetic pentasaccharides, or warfarin with an INR goal of < or =2.0. Patients at standard risk of PE and at elevated (above standard) risk of major bleeding should be considered for aspirin, warfarin with an INR goal of < or =2.0, or none. Patients at elevated (above standard) risk of both PE and major bleeding should be considered for aspirin, warfarin with an INR goal of < or =2.0, or none.

Mechanisms of the Factor V Leiden Paradox

Objective— Carriers of the factor V Leiden mutation (FVL-carriers) have a substantially increased risk of deep venous thrombosis (DVT), whereas the risk of pulmonary embolism (PE) is only mildly increased compared with noncarriers. So far few studies have investigated possible mechanisms for this so-called FVL paradox.

Methods and Results— Consecutive patients with a first DVT or PE were included in a large population-based case-control study (MEGA study). Patients, aged 18 to 70 years, provided a questionnaire, DNA (n=3313), or plasma (n=1474). Surgery, injury, and travel were considered thrombosis-provocative. Of 2063 patients with isolated DVT, 20% were FVL-carrier, as were 8% of the 885 patients with isolated PE. Among DVT patients, FVL-carriers had their thrombi more often proximal and a higher number of affected veins than noncarriers. No differences were observed between FVL-carriers and noncarriers in time between provocation and diagnosis, in vitro coagulation time, and thrombus density. Compared with patients with both DVT and PE, isolated DVT patients more often had thrombi located distally and had a similar number of affected veins. Compared with isolated PE patients, isolated DVT patients had a similar time between provocation and diagnosis, and similar in vitro coagulation time and thrombus density.

Conclusion— Although some effects were differential for FVL-carriers and noncarriers, and some were differential for PE and DVT patients, none of the potential mechanisms offered a clear explanation.

Type and Location of Venous Thromboembolism in Carriers of Factor V Leiden or Prothrombin G20210A Mutation Versus Patients With No Mutation

Factor V Leiden (FVLeiden) and prothrombin G20210A are the most common genetic causes of thrombophilia and established risk factors for different clinical manifestations of venous thromboembolism (VTE). This study investigated whether the clinical manifestation of VTE, the extension of deep vein thrombosis (DVT) and the presence of transient risk factors at the time of the first VTE, differed among patients with mutations (97 with FVLeiden; 33 with prothrombin G20210A) and in 109 patients without thrombophilia. Isolated pulmonary embolism (PE) was less prevalent in patients with FVLeiden (6%) and no thrombophilia (6%) than in those with prothrombin G20210A (15%). No difference was found in the incidence of distal DVT. Regarding the extension of proximal DVT, the lowest incidence for isolated popliteal vein and the highest for iliofemoral vein were observed in patients with prothrombin G20210A. No difference was observed between groups of patients with or without thrombophilia by unprovoked VTE. The pregnancy/puerperium was the most prevalent risk factor in carriers of prothrombin G20210A. Among FVLeiden carriers, the most prevalent risk factor was surgery, and in patients without thrombophilia, it was trauma ( P < .05). Thrombosis of the upper limb was more frequent in a group without thrombophilia than in patients with mutations ( P < .01). Transverse sinus venous thrombosis was present only in patients with prothrombin G20210A. Carriers of prothrombin G20210A have an increased risk of developing isolated PE and more severe clinical manifestations than those with FVLeiden or without thrombophilia.

Heritable thrombophilia-hypofibrinolysis and osteonecrosis of the femoral head

We hypothesized that inherited thrombophilia and hypofibrinolysis were risk factors for osteonecrosis of the femoral head. We compared measures of thrombophilia and hypofibrinolysis in referred new adult patients with idiopathic osteonecrosis (n = 71) or secondary osteonecrosis (n = 62) with the same measures in sex- and race-matched healthy control subjects. Heritable thrombophilic Factor VIII and hypofibrinolytic Lp(a) were more frequently high in the 71 patients with idiopathic osteonecrosis than in control subjects. High Factor VIII, Factor V Leiden heterozygosity, and resistance to activated protein C, all heritable thrombophilias, were more frequently present in the 62 patients with secondary osteonecrosis than in control subjects. Our data suggest inherited thrombophilia and hypofibrinolysis are risk factors for both idiopathic and secondary osteonecrosis of the head of the femur.

The 2007 ABJS Nicolas Andry Award: three decades of clinical, basic, and applied research on thromboembolic disease after THA: rationale and clinical results of a multimodal prophylaxis protocol

Total hip arthroplasty is an operation with a high risk for venous thromboembolism. Three decades of research conducted at the Hospital for Special Surgery identified the exact timing of the thrombogenic stimulus during surgery, defined the role of magnetic resonance venography, and established the role of certain genetic and acquired predispositions. Based on these studies, we implemented a multimodal prophylaxis consisting of a series of safe preventive measures applied before, during, and immediately after surgery to reduce the risk of venous thromboembolism. If these safe preventive measures are strictly observed, postoperative pharmacologic prophylaxis does not need to be aggressive in the patient without predisposing factors who mobilizes promptly, thus diminishing the risk of bleeding associated with the use of anticoagulants and the overall cost of care. Our clinical experience with more than 5000 total hip arthroplasties performed during the last decade and closely followed prospectively for a minimum of 3 months clearly shows this multimodal prophylaxis is safe and effective resulting in a very low prevalence of thromboembolism.

Mini-gastric bypass in a patient homozygous for Factor V Leiden

A 42-year-old morbidly obese female, homozygous for Factor V Leiden, underwent mini-gastric bypass without complications. The recommendations for prophylaxis in this high-risk population are unclear and most likely involve a combination of pharmacologic and non-pharmacologic measures.

Inherited risk factors for deep venous thrombosis following total hip arthroplasty in Japanese patients: matched control study

BACKGROUND

Inherited predisposing risk factors for deep venous thrombosis (DVT) have been clearly identified in Caucasians, but there are fewer reports evaluating these factors in the Japanese. This study was undertaken to assess the predisposing risk factors for DVT following elective total hip arthroplasty (THA) in Japanese patients.

METHODS

We studied 60 patients who underwent THA. The study group consisted of 30 patients who developed DVT diagnosed by duplex sonography examination; the 30 patients who did not develop DVT served as a control group. They were matched in age, sex distribution, diagnosis (osteoarthritis secondary to dysplastic hip), and operation side(s) (bilateral or unilateral). Protein C, protein S, antithrombin III, and plasminogen activities and the plasma homocysteine level were measured. Three polymorphisms were screened for the factor V Leiden polymorphism, the factor II G20210A polymorphism, and the methylene tetrahydrofolate reductase C677T polymorphism.

RESULTS

Plasma protein C activity was 82.39% +/- 14.24% in the DVT patients and 88.76% +/- 23.27% in the controls. Plasma protein C activity was significantly reduced in the study group, whereas other serologic and genetic analyses revealed no significant differences.

CONCLUSIONS

Three genetic risk factors established in Caucasian patients are not valuable for evaluating DVT risk in Japanese patients. Reduced protein C activity may be a risk factor for DVT after THA.

Thromboembolic disease after total hip arthroplasty: who is at risk?

The strong activation of the clotting cascade that occurs during total hip arthroplasty places patients at increased risk for venous thromboembolism. The risk is higher in those patients with the following predisposing factors, listed in approximate order of importance: hip fracture; malignancy, particularly if associated with chemotherapy; antiphospholipid syndrome; immobility; history of venous thromboemholism; administration of tamoxifen; raloxifene; oral contraceptives or estrogen; morbid obesity; stroke; atherosclerosis; and an American Society of Anesthesiologists physical status classification of 3 or greater. The following risk factors are weak or controversial: advanced age; diabetes mellitus; congestive heart disease; atrial fibrillation; varicose veins; and smoking. However, 50% of patients who develop thromboembolism after total hip arthroplasty have no clinical predisposing factors. In a matched, controlled study, we defined the major genetic predispositions that increase the risk of venous thromboembolism after total hip arthroplasty: deficiency of antithrombin III (< 75%) and protein C (< 70%), and prothrombin gene mutation. Preoperative genetic screening in conjunction with the recognized clinical risk factors can help categorize postoperative venous thromboembolism risk and differentiate patients who can be protected with milder and safer prophylaxis (eg, aspirin, intermittent pneumatic compression) compared with those at higher risk who need to be anticoagulated.

Risk of recurrent venous thromboembolism or bleeding in relation to thrombophilic risk factors in patients receiving ximelagatran or placebo for long-term secondary prevention of venous thromboembolism

The impact of prothrombotic abnormalities on the risk of recurrent venous thromboembolism (VTE) and bleeding in patients receiving long-term anticoagulation remains unclear. This analysis evaluated the influence of potential prothrombotic risk factors (antithrombin, protein C, protein S, factor V Leiden mutation, prothrombin gene G20210A mutation, cardiolipin antibodies, number of risk factors) on the risk of recurrent VTE or bleeding during treatment with oral ximelagatran (24 mg twice daily) or placebo for 18 months [THRombin Inhibitor in Venous thromboEmbolism (THRIVE) III trial]. Of the 1223 patients in the intention-to-treat population, prothrombotic state was analysed in 559 patients receiving ximelagatran and 540 patients receiving placebo. It is possible that patients at a high risk of recurrent VTE were poorly represented in this analysis because of selection bias. Prothrombotic risk factors were reported in 41% of patients (8% had > or = 2 factors). No significant interactions were found between ximelagatran treatment and potential prothrombotic risk factors for the risk of recurrent VTE or bleeding by Cox proportionate hazard modelling. There was no clear evidence for a higher risk of recurrent VTE or bleeding across subgroups according to the potential prothrombotic factors analysed in this study.