***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Venous thromboembolic disease remains the most common reason for readmission after total hip arthroplasty . Prospect i ve analysis of screening contrast venography was done from 1984 to 2003 in 1972 patients having elective total hip arthroplasty . Patients with deep venous thrombosis or pulmonary embolism received warfarin therapy ; those with negative venograms received no further anticoagulation . From 1984 to 1992 , patients not completing venography were discharged without warfarin ; since 1993 , patients without venography received warfarin for 6 weeks . Readmission for deep venous thrombosis , pulmonary embolism , or bleeding was tracked for 6 months . Venograms were completed in 1032 patients ; 175 ( 16.9 % ) had deep venous thrombosis .  Deep venous thrombosis was reduced by a clinical pathway that included continuous epidural anesthesia ( 14.2 % versus 22.5 % ) . The overall readmission rate for venous thromboembolic disease was 1.62 % , including 14 pulmonary emboli ( three fatal ) and 18 femoral deep venous thrombosis . Readmission occurred in 0.27 % ( 1 of 360 ) patients on continued warfarin , compared with 2.2 % ( 19 of 880 ) with negative venograms discharged without further anticoagulation . Three patients ( 0.15 % ) suffered fatal pulmonary emboli ; all had negative venograms and received no outpatient prophylaxis . Extended outpatient warfarin therapy provided effective protection against venous thromboembolic disease readmission . Surveillance venography  was a poor predictor of need for continued prophylaxis ; all patients should have extended anticoagulation after total hip arthroplasty . Level of Evidence : Therapeutic study , Level I-1 ( high- quality r and omized trial with statistically significant difference or no statistically significant difference but narrow confidence intervals ) . See the Guidelines for Authors for a complete description of levels of evidence There are many reports concerning the aetiology and prophylaxis of deep-vein thrombosis ( DVT ) but little is known about its natural history . The purpose of our study was to identify the incidence and site of DVT , the risk factors for pulmonary embolism and the natural history of DVT  after total hip replacement ( THR ) in patients who do not receive any form of prophylactic or therapeutic treatment for DVT . Two hundred patients who had a primary THR were included : 100 had one-staged bilateral THR and 100 had unilateral THR and 150 implants were cemented and 150 cementless .  Coagulation assays , a full blood count , blood typing and serum chemical profile tests were performed for all patients on three separate occasions . Bilateral simultaneous or unilateral venograms were performed on the sixth or seventh postoperative day and perfusion lung scans preoperatively and on the seventh or eighth postoperative day . Further venograms were performed in all patients who had thrombi six months later . In the patients with bilateral THR , 52 ( 26 % ) venograms were positive for thrombi , while in the patients with unilateral THR 20 ( 20 % ) were positive ( p = 0.89 ) . In the patients with a cemented THR , 31 venograms ( 20.7 % ) were positive for thrombi , while in those with a cementless THR 41 ( 27.3 % ) were positive ( p = 0.654 ) . Further venograms in all 72 patients who had thrombi at six months after operation showed that they resolved completely and spontaneously regardless of their site and size . No patients had symptoms of pulmonary emboli and none were seen on the perfusion lung scans . Two patients died from unrelated causes . Although the prevailing opinion is that patients with proximal venous thrombosis should be treated with anticoagulants , our study has shown that all thrombi regardless of their site and size resolve spontaneously without associated pulmonary embolism Intraoperative pulmonary embolism occurs not only during cemented but also during cementless total hip arthroplasty ( THA ) . We determined whether the ROBODOC femoral milling system can reduce intraoperative pulmonary embolism , by using of transesophageal echocardiography and hemo-dynamic monitoring . We did a prospect i ve clinical trial with 71 patients ( 75 hips ) who were divided into 2 groups : group 1 , 46 patients ( 50 hips ) who underwent cementless THA with preparation of the femoral canal using ROBODOC ; group 2 , 25 patients ( 25 hips ) who underwent conventional cementless THA surgery in whom separate measurements were made during preparation of the femur , insertion of the stem and relocation of the hip . The incidence of severe embolic events was lower in group 1 than in group 2 . Our findings suggest that the ROBODOC femoral milling system may reduce the risk of clinical ly significant pulmonary embolism during cementless Introduction This prospect i ve study was design ed to confirm risk factors and to assess the incidence of deep vein thrombosis after total hip and surface replacement arthroplasty in Korean patients not receiving anticoagulation prophylaxis and to determine efficacy of plasma D-dimer levels as a screening test . Material s and methods From May 2003 to August 2004 , 221 consecutive patients undergoing unilateral total hip arthroplasty and hip resurfacing were evaluated . All patients underwent ultrasonography preoperatively and venography and /or ultrasonography on postoperative day 7 . Plasma D-dimer levels were estimated by latex immuno-assay preoperatively and on days 3 and 7 postoperatively . Results Of the 221 patients in our cohort , 23 developed deep vein thrombosis ( 10.4 % ) . Age ( r = 0.245 , P < 0.001 ) and gender ( r = 0.155 , P = 0.021 ) significantly correlated with deep vein thrombosis . Rise in incidence paralleled increase in age ( X2 = 32.860 , P < 0.001 ) . D-dimer levels on postoperative days 3 ( γ = 0.364 , P < 0.001 ) and 7 ( γ = 0.470 , P < 0.001 ) were significantly correlated to the development of DVT . Conclusion While incidence of deep vein thrombosis in Korean population after THA was lower than that in the West ; it increased with age , and in female gender . Significant correlation was found between D-dimer levels and the development of deep vein thrombosis Introduction : The incidence of venous thromboembolism ( VTE ) in Western population s undergoing major orthopaedic surgery without any thromboprophylaxis has been reported to range from 32 % to 88 % . There is however limited information on incidence of VTE in Indian patients and most of the Indian patients undergoing these surgeries do not receive any form of prophylaxis regardless of their risk profile . Methods : A prospect i ve study was performed on 147 patients undergoing major orthopaedic surgery for total knee replacement ( TKR ) , total hip replacement ( THR ) , and proximal femur fracture fixation ( PFF ) without any prophylaxis .  These patients were profiled for presence of the known risk factors responsible for development of VTE . A duplex ultrasound on both lower limbs was done 6 to 10 days after surgery . Twenty three patients underwent THR , 22 patients underwent TKR , and 102 underwent surgery for PFF . The patients were assessed clinical ly for any signs of deep venous thrombosis ( DVT ) and pulmonary embolism ( PE ) . A helical CT scan was done in case of suspicion of PE and a duplex ultrasound was done in case of clinical suspicion of DVT irrespective of the stage of study . Results : The overall incidence of VTE was 6.12 % and that of PE was 0.6 % . The risk factors that were found to be significantly responsible for development of VTE ( p < 0.05 ) were : immobility greater than 72 hours , malignancy , obesity , surgery lasting more than two hours . Conclusion : The study reconfirms the belief that DVT has a lower incidence in Indian patients as compared with other ethnic groups BACKGROUND In view of recent substantial changes in the management of orthopedic surgery patients , a study was performed in order to up date data on the epidemiology of venous thromboembolism ( VTE ) in patients undergoing lower limb arthroplasty according to contemporary practise . METHODS We performed a prospect i ve observational study of a cohort of consecutive patients hospitalized for total hip or knee replacement in June 2003 . The primary study outcome was the incidence of symptomatic VTE at 3 months . All events were adjudicated by an independent critical event committee . RESULTS Data from 1080 patients ( mean age 68.0 years ) were available ; 63.2 % were undergoing total hip replacement and 36.8 % total knee replacement . Pharmacological thromboprophylaxis was administered for a mean time of 36 days . Injectable antithrombotics were used in more than 99 % of patients , irrespective of the type of surgery . The incidence of the primary study outcome was 1.8 % ( 20 events ; 95 % CI : 1.0 - 2.6 % ) . The incidences were 1.3 % and 2.8 % in hip and knee surgery patients , respectively . There were two pulmonary embolisms , both in knee surgery patients ; neither was fatal . Thirty-five per cent of VTEs occurred after hospital discharge . An age of at least 75 years and the absence of ambulation before hospital discharge were the only significant ( P < 0.05 ) predictors of VTE . The rate of clinical ly significant bleeding was 1.0 % and the rate of death was 0.9 % . CONCLUSIONS The incidence of symptomatic VTE after lower limb arthroplasty is low , even if there is still a need to improve thromboprophylaxis , notably in patients undergoing knee arthroplasty Background Heparin-induced thrombocytopenia ( HIT ) is a thromboembolic complication that can occur with unfractionated heparin ( UFH ) or low molecular weight heparin ( LMWH ) . Our objective was to determine and compare the incidence of IgG-class HIT antibodies in patients undergoing total hip arthroplasty ( THA ) or total knee arthroplasty ( TKA ) with different antithrombotic prophylaxis therapies  and their contributions to the occurrence of venous thromboembolism ( VTE ) . Methods A prospect i ve observational study was performed for 374 Japanese patients undergoing THA or TKA to determine the incidence of VTE .  IgG-class anti-PF4/heparin antibodies were measured using IgG-specific EIA before and after the operation . Results In the clinical outcome , the incidence of symptomatic deep vein thrombosis ( DVT ) was 15.0 % ( 56/374 , TKA ; 35 , THA ; 21 ) and pulmonary emboli ( PE ) were not observed . The total seroconversion incidence of IgG-class PF4/heparin antibodies was 19.8 % ( 74/374 ) . The seroconversion incidence of IgG-class PF4/heparin antibodies was higher in patients receiving UFH ( 32.7 % ) compared to those receiving LMWH ( 9.5 % ) or fondaparinux ( 14.8 % ) . Furthermore , the seroconversion incidence was significantly higher in patients undergoing TKA compared to those undergoing THA . Based on multivariate analysis , seroconversion of the IgG-class PF4/heparin antibodies was independent a risk factor for symptomatic DVT . Conclusion Our findings show that the seroconversion of IgG-class anti-PF4/heparin antibodies differed with various anti-thrombotic prophylaxis therapeutics and was associated with the risk of DVT in a subset of patients undergoing total joint arthroplasty ( TKA and THA ) Venous thromboembolism ( VTE ) is an important complication of major orthopaedic surgery of the lower limbs . Fondaparinux , a synthetic pentasaccharide and highly selective inhibitor of activated Factor Xa , is the first in a new class of antithrombotic agents . To determine the optimal dose in Japanese patients , double-blind , placebo-controlled , dose-ranging studies of fondaparinux were conducted in patients undergoing total knee replacement ( TKR ) or total hip replacement ( THR ) surgery . Patients were r and omly assigned to receive a once-daily subcutaneous injection of fondaparinux ( 0.75 , 1.5 , 2.5 , or 3.0 mg ) or placebo in Study 1 ( TKR ) and Study 2 ( THR ) . In Study 1 , the incidence of VTE was 65.3 % in the placebo  group and was 34.2 % , 21.3 % , 16.2 % , and 9.5 % in the groups receiving 0.75 , 1.5 , 2.5 , and 3.0 mg fondaparinux respectively . In Study 2 , the incidence of VTE was 33.8 % in the placebo group and was 24.2 % , 4.6 % , 7.4 % , 
    Output:
    
VTE history was found as a VTE risk factor of THA but an controversial factor of TKA .
Cemented fixation as compared to cementless fixation was found as a risk factor for VTE only of TKA .
TKA surgery itself was confirmed as a VTE risk factor compared with THA surgery .
Conclusions This systematic review of high level evidence s published in recent ten years identified a range of potential factors associated with VTE risk of total joint arthroplasty .