**1. Introduction**

The importance of DVT prophylaxis is well understood from the high incidence of DVT in patients undergoing total knee arthroplasty (TKA). Studies have shown that without any mechanical or pharmacologic prophylaxis, asymptomatic DVT develops in 40–60% of the patients undergoing total hip and knee arthroplasties. Hence, there is a general consensus that these patients require regular prophylaxis even beyond discharge [1]. Venous thrombosis, including deep-vein thrombosis, occurs at an annual incidence of about 1 per 1000 adults and is higher in men than that in women in older age. DVT incidence varies according to

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

the race and ethnicity. Asians have a very low incidence of deep-vein thrombosis due to the preferred vegetarian diet, low prevalence of obesity, hyperlipidemia, and Factor V Leiden mutation. Several meta-analysis studies have shown similar results of low DVT incidence in Asians [2]. Operating surgeon has to minimize the risk of occurrence of this complication and its associated morbidity and mortality. Surgeon's choice of VTE prophylaxis should be based on a balance between safety and efficacy of a particular anticoagulant, with risk stratification of VTE or bleeding. Virchow's triad of events—stasis, vascular endothelial injury, and hypercoagulability, increases the risk of deep-vein thrombosis (DVT). Patients who fulfill two of the three criteria are considered to be high-risk group. Most of the patients undergoing TKA are considered to be at high risk for DVT for the high incidence of endothelial injury during the surgery and the relative stasis during the postoperative period. Well's criteria help us to stratify risk in these patients (**Figure 1**).

Patients without prior clinical suspicion also can develop DVT and fatal pulmonary embolism. Hence, it is therefore important to take appropriate preoperative screening and preventive measures for all these patients and to determine which of them warrant additional prophylaxis. Worldwide accepted guidelines on DVT prophylaxis have been produced by the American College of Chest Physicians (ACCP), American Academy of Orthopedic Surgeons (AAOS), and the National Institute for Health and Clinical Excellence (NICE). But the priority consideration is to diagnose the patients with high risk of developing

Methods of DVT Prophylaxis after Total Knee Arthroplasty

http://dx.doi.org/10.5772/intechopen.73645

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The risk factors for the development of DVT can be modifiable or nonmodifiable factors.

• Obesity: it is defined as BMI above 30. Obesity leads to a two- to threefold higher risk of venous thrombosis in men and women. The obese have a further increase in thrombosis risk when they are exposed to other thrombosis risk factors, such as exogenous contracep-

• Homocysteine levels: elevated homocysteine has been consistently reported as a risk factor for venous thrombosis and levels can be reduced with B vitamin supplementation.

Nonmodifiable risk factors include the genetic factors which cause thrombophilic disorders. Protein C, protein S, and antithrombin deficiencies, Factor V Leiden mutation, and increased level of factor V, VII, VIII, IX, XI and von Willebrand factor are a few of the conditions that

Triggering factors are incidental situations which put patients into high risk of developing

• Immobility—due to stasis of blood flow as in cases of plaster casts, bed rest, and paresis of

• Cancer—increased risk due to cancer cells activating coagulation and tumors compressing

• Travel—duration of any form of travel more than 4 h increases the risk by about twofold

DVT.

**2. Risk factors**

Modifiable factors include

add up the risk of DVT.

• Surgery/trauma.

tive or postmenopausal hormones.

DVT, which cannot be avoided but can be tided over.

legs due to neurological conditions.

for several weeks after travel [3].

veins causing hemostasis.

• Hospitalization—either due to immobility, infection, surgery.


**Figure 1.** Well's criteria for DVT risk stratification.

Patients without prior clinical suspicion also can develop DVT and fatal pulmonary embolism. Hence, it is therefore important to take appropriate preoperative screening and preventive measures for all these patients and to determine which of them warrant additional prophylaxis. Worldwide accepted guidelines on DVT prophylaxis have been produced by the American College of Chest Physicians (ACCP), American Academy of Orthopedic Surgeons (AAOS), and the National Institute for Health and Clinical Excellence (NICE). But the priority consideration is to diagnose the patients with high risk of developing DVT.
