Objective: Deep vein thrombosis (DVT) after total knee arthroplasty (TKA) is very common and leading cause of death due to this procedure. The objective of this study was to investigate the incidence and clinical characteristics of DVT after TKA with DVT chemoprophylaxis. Methods: This is a prospective cohort study in single institution. The patients received postoperative DVT chemoprophylaxis (low molecular weight heparin (LMWH) or Fondaparinux), followed by duplex ultrasonography to check for DVT 1 - 2 weeks after TKA. The clinical characteristics were summarized and analysed by chi-square test and regression analysis. Results: Five hundred and thirty four patients were enrolled from January 2007 to December 2010. DVT chemoprophylaxis was administered in 524 (98.1%) of the 534 patients. DVT occurred in 9 subjects (1.69%); 8 subjects had DVT in the leg, and 1 subject had a pulmonary embolism. Among them, asymptomatic DVT was observed in 5 patients (0.94%). Univariate analysis showed that surgical methods (revision, P = 0.0007), body mass index (BMI) (>25, P = 0.0028), low platelet count (less than 150 × 10 3, P = 0.0219), time in the intensive care unit (ICU) (P < 0.0001), no administration of prophylactic LMWH (P = 0.0392), and a history of DVT (P < 0.0001) were significant risk factors of DVT. Conclusions: The incidence of DVT was 1.69% after TKA with prophylactic antithrombotic therapy. Revision surgery, BMI, low platelet count, time in ICU, absence of prophylactic LMWH and history of DVT were significant risk factors of DVT.
In the United States and Europe, venous thromboembolism has gained attention due to the associated morbidity, mortality, and increased treatment costs. Guidelines for deep vein thrombosis (DVT) prophylaxis are being proposed [
This study was designed as prospective cohort study. The patient who received total knee arthroplasty de novo or as a follow-up surgery (revision) at Seoul St. Mary’s Hospital from 2007 to 2010 was included in this study. The patient received DVT chemoprophylaxis and was followed by duplex scan 1 - 2 weeks after TKA. IRB (institutional review board) approval was obtained prior to the study. For DVT chemoprophylaxis, low molecular weight heparin (LMWH, Enoxaparin) or Fondaparinux (mg) was administered before and after surgery in patients who underwent TKA without leg edema. Duplex ultrasonography was carried out within 1 - 2 weeks (average 8.7 days) after the surgery to confirm the presence or absence of iliofemoral and below knee DVT. The registered vascular technician examined the iliac vein, femoral vein, popliteal vein, tibial veins, peroneal veins and calf muscle veins in both legs. The DVT in the iliofemoral vein was considered as proximal vein DVT and the DVT in below the knee vein was considered distal vein DVT. When pulmonary embolism (PE) was suspected, a diagnosis was conducted via pulmonary arterial computed tomography. The clinical characteristics of patients (Gender, age, surgery types, BMI clinical records, history of thrombotic vein thrombosis, and comorbid diseases, including malignant cancers) were investigated through medical and imaging records. Statistical analyses were performed by chi-square test and regression analysis using SAS software (version 9.3).
Five hundred thirty four patients were enrolled from January 2007 to December 2010.
Average and standard deviation or rate (%) | ||
---|---|---|
Gender (M/F) | 51(9.55)/483(90.45) | |
Age | 68.72 ± 9.13 | |
Duration of admission | 11.93 ± 9.53(5 - 76) | |
Types of operation | Primary total knee replacement | 479(89.70) |
Revision surgery | 55(10.30) | |
Body mass index (kg/m2) | 25.99 ± 3.89 | |
Laboratory findings | Hematocrit (%) | 37.86 ± 4.02(14.10 - 49.30) |
Platelet count (×103) | 243.59 ± 72.88(34.4 - 664.0) | |
Serum creatinine level (mg/dl) | 0.98 ± 1.81(0.34 - 24.40) | |
Compression stockings-wearing | 366(68.54) | |
Administration of prophylactic anticoagulation | 524(98.13) | |
Kinds of prophylactic anticoagulation | Enoxaparin | 241(45.99) |
Fondaparinux | 283(54.01) | |
Comorbidities | Diabetes | 104(19.48) |
Hypertension | 325(60.86) | |
Past history of tuberculosis | 6(1.12) | |
Coronary artery disease | 50(9.36) | |
Cerebrovascular disease | 19(3.56) | |
Chronic renal failure | 11(2.06) | |
Chronic obstructive pulmonary diseases | 8(1.50) | |
Malignancies | 31(5.81) | |
Hyperlipidemia | 9(1.69) | |
Personal history of venous thromboembolism | 1(0.19) |
subject had a PE. Five patients (0.94%) showed asymptomatic DVT (
DVT is the leading cause of in-hospital death in the United States. However, it is a preventable disease, and its mortality rate can be lowered through prevention. As such, US surgeons have prepared guidelines to reduce the morbidity and mortality caused by venous thromboembolism [
Type of Embolism | No. of Patients (%) |
---|---|
Symptomatic/Asymptomatic DVT | 3/5(0.56/0.94) |
Distal DVT | 4(0.75) |
Proximal DVT | 4(0.75) |
Symptomatic PE | 1(0.19) |
Total VTE | 9(1.69) |
Proximal DVT: iliofemoral DVT; Distal DVT: Below knee vein DVT.
Parameters | DVT or PE group (n = 9) | Control group (n = 525) | P value | |
---|---|---|---|---|
Female gender | 7(77.78) | 476(90.67) | 0.1291 | |
Age ≥ 65 yr | 8(88.89) | 383(72.95) | 0.2844 | |
Hospital stay over 2 wks | 3(33.33) | 88(16.76) | 0.1899 | |
Revision Sugery | 4(44.44) | 51(9.71) | 0.0007 | |
BMI ≥ 25 (kg/m2) | 1(11.11) | 317(60.38) | 0.0028 | |
Laboratory findings | Hematocrit < 38% | 6(66.67) | 250(47.62) | 0.2567 |
Platelet count < 150 × 103 | 3(33.33) | 52(9.90) | 0.0219 | |
Serum creatinine > 1.2 (mg/dl) | 2(22.22) | 94(17.90) | 0.7380 | |
ICU stay | 3(33.33) | 15(2.86) | <0.0001 | |
Use of compression stockings | 6(66.67) | 360(68.57) | 0.9029 | |
Administration of prophylactic anticoagulation | 8(88.89) | 516(98.29) | 0.0392 | |
Prophylactic anticoagulation (Enoxaparin/Fondaparinux) | 6(66.67) | 235(44.76) | 0.1904 | |
Comorbidities | Diabetes | 2(22.22) | 102(19.43) | 0.8338 |
Hypertension | 5(55.56) | 320(60.95) | 0.7422 | |
Coronary artery disease | 0(0.00) | 50(9.52) | 0.3308 | |
Cerebrovascular disease | 0(0.00) | 19(3.62) | 0.5611 | |
Chronic renal failure | 0(0.00) | 11(2.10) | 0.6608 | |
Chronic obstructive pulmonary diseases | 0(0.00) | 8(1.52) | 0.7090 | |
Malignancies | 1(11.11) | 30(5.71) | 0.4924 | |
Hyperlipidemia | 0(0.00) | 9(1.71) | 0.6920 | |
Personal history of venous thromboembolism | 1(11.11) | 0(0.00) | <0.0001 | |
Local complication | 1(11.11) | 22(4.19) | 0.3106 |
VKA is strongly recommended for at least 10 days for antithrombotic prophylaxis (Grade 1B). Furthermore, the recommendations suggest extending the administration of such drugs by more than 2 weeks, up to 5 weeks (35 days) (Grade 2B). Recently, recommendations have also been provided by Asia [
Based on a univariate analysis of this study, surgical types, BMI, platelet count, visit to the intensive care unit (ICU), and history of VTE were shown as risk factors.
Elective TKA and revision showed incidence rates of 1.3% and 14.2% in subjects who were placed in intensive care, respectively. In addition, there were differences in the mean length of ICU stay, 1.83 days in the group of Elective TKA vs. 3.5 days in the group of revision, indicating that the difference in VTE incidence is because of intensive care placement status as well as the duration of the stay based on the type of surgery. The factors that are most commonly reported as risk factors, including long-term hospitalization (more than 2 weeks), female, elderly (older than 65 years), cardiovascular disease, and malignant tumors were shown to be weakly associated based on the results of this study. Unexpectedly, BMI was smaller in the DVT group; this may be a statistical error due to the considerably low DVT incidence, unlike other studies, especially due to the relatively lower morbid obesity rate compared to the West. According to a SMART study [
The incidence of DVT was 1.69% after TKA surgery with DVT chemoprophylaxis in this study. Revision surgery, BMI, low platelet count, time in ICU, absence of prophylactic LMWH and history of DVT were significant risk factors of DVT. DVT chemoprophylaxis was effective to prevent DVT compared to previously reported incidence of DVT without DVT chemoprophylaxis. This rate is relatively low compared to studies conducted in the West. Therefore, prospective multicenter and randomized studies regarding VTE prophylactic treatments need to be performed in the future. In particular, detailed studies are warranted with regards to the length of ICU stay and the frequency of VTE to find effective treatments for patients who are expected to stay in an ICU.