**4. DVT prophylaxis guidelines**

**3. Evaluation**

44 Primary Total Knee Arthroplasty

that mimic PE.

procedure.

thrombi in the venous system.

quick, noninvasive, cheap and patient-friendly.

obstruction somewhere indicates a thrombus.

detect even an occult event of pulmonary embolism.

bination, to reduce the risk of postoperative VTE.

Apart from the history and the classic clinical symptoms and examination findings of pain, tenderness, and swelling of the leg, different techniques are employed to detect even small

*Ultrasound Doppler*: it is the most common test used for diagnosing deep-vein thrombosis. It is

*Venography*: this test is indicated if ultrasound does not provide a clear diagnosis. It is an invasive technique whereby a radio-opaque dye is injected into a vein, and then, a radiograph is taken of the leg. The entire pathway of the vein can be identified from the X-ray, and any

*Impedance plethysmography*: changes in venous filling are produced by inflating and deflating the thigh cuff, and electrodes sense the change in blood volume by electrical impedance in the calf veins. A delay indicates that an occlusive thrombus is present in the popliteal or more

*Ventilation–Perfusion Scan (V/Q scan)*: a lung V/Q scan uses a ventilation (V) scan to measure air flow in the lungs and a perfusion (Q) scan to assess the blood flow in the lungs. This will

*Pulmonary CT angiography*: currently, the most commonly used first-choice imaging examination in patients with suspected PE is pulmonary CT angiography [4]. This recommendation is based on high sensitivity and specificity for PE and other clinically important conditions

But the point of interest is to prevent the occurrence of DVT rather than its detection. All these modalities are used to detect even a minute thrombus occurring in the system. Apart from the identification of high-risk patients, it would be better to screen all these patients for DVT preoperatively. So many studies have been done in this regard in different population using preoperative Doppler screening studies. According to the Scottish Arthroplasty Registry, the incidence of clinically significant VTE within 3 months of TKA is 1.79%, whereas that of fatal PE is 0.15% [5] and the asymptomatic DVT rates are much higher. Therefore, thromboprophylaxis use has been recommended for all patients undergoing TJA in Western population. Many other regional studies have shown that the incidence of DVT in patients undergoing TKA is so less to warrant a regular preoperative Doppler screening. However, it is said that a better modality to detect thrombi would be venography, which is not an appealing invasive

Numerous guidelines and recommendations suggest the use of various methods of thromboprophylaxis and methods to reduce the risk of development of modifiable factors. Pharmacological and mechanical prophylaxis methods are used, either in isolation or in com-

proximal veins. But this modality is not useful in detecting more proximal DVTs.

*D-dimer test*: the level of D dimer will be elevated in the presence of a blood thrombus.

ACCP 2012 guidelines recommend thromboprophylaxis for patients undergoing TJA for a minimum of 10–14 days. They prefer agents like low molecular weight heparin (LMWH), vitamin K antagonist, aspirin, fondaparinux, apixaban, dabigatran, or rivaroxaban. Regular Doppler screening during postoperative period is not recommended. But, prophylaxis is advocated as it is recognized that asymptomatic DVT can produce a fatal PE [6] (**Figure 2**).


**Figure 2.** Highlights of the recent ACCP guidelines for thromboprophylaxis.

The AAOS 2011 guidelines suggest pharmacologic agents and/or mechanical device for the prevention of VTE following joint replacement surgery. They did not recommend any specific agent or duration of thromboprophylaxis. Both guidelines support combined methods of chemoprophylaxis with mechanical device. Also, they discourage the regular Doppler screening for DVT postoperatively [7] (**Figure 3**).

activated coagulation factors, and promote lymphatic drainage in adjacent tissues. It avoids the side effects of the anticoagulant drugs such as wound drainage, hematoma, and gastrointesti-

Methods of DVT Prophylaxis after Total Knee Arthroplasty

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

47

*Early mobilization*: it has shown that early mobilization reduces the incidence of DVT in patients undergoing TJA [8]. Patients are encouraged to be mobilized as soon as feasible. These act by increasing the velocity of venous blood flow and preventing stasis as well as decreasing the coagulability of blood by stimulating fibrinolysis. Early mobilization is the simplest, cheapest, and easiest method to prevent DVT after any surgery. The more you mobilize the patient on the first postoperative day, much lesser is the DVT incidence. The incidence reduces by a third in those who mobilize more than 1 m on the first postoperative day, and it reaches zero in those who mobilize more than 5 m [9]. Physical methods can be combined with pharmaco-

*Intermittent pneumatic compression device* (*IPCD*): inflatable garments are wrapped around the legs, which are intermittently inflated by a pneumatic pump enhancing venous return. Two meta-analyses found that rates of DVT after total knee arthroplasty were much lower with intermittent pneumatic compression devices or LMWH (17–29%) than with aspirin or warfa-

*Foot impulse devices* (or foot pumps): it increases venous outflow and reduces stasis in immobilized patients. It artificially compresses the venous plexus around the sole, mimicking normal

*Aspirin*: it is an inhibitor of the cyclooxygenase enzyme system. It is the most simple and commonly used drug for thromboprophylaxis. It is very cheap, patient compliant and with least side effects. Aspirin inhibits COX1 more than COX2. COX1is chiefly expressed on platelets, which helps in platelet aggregation. Meta-analysis showed that aspirin was effective in reducing the rate of DVT to 30.6% from 48.5% [11]. Conflicting literature exists with regard to the efficiency of aspirin in preventing DVT. Aspirin is inferior to warfarin or LMWH in terms of preventing symptomatic PE or proximal DVT [8]. Also, the rate of complications is very low with the use of aspirin. Pulmonary embolism prevention (PEP) trial [12] which concluded that low-dose aspirin, when taken for 35 days, would result in seven times less symptomatic DVT cases, but three bleeding cases and two nonfatal myocardial infarction per 1000 patients. Studies have shown up to 0.13% developing hematoma and bleeding with warfarin in comparison to 0% with aspirin [13]. Studies have been done comparing the incidence of VTE, PE, proximal DVT, and distal DVT in multimodal prophylaxis methods with aspirin and warfarin. They have showed lower incidence of all types of thromboses with

*Warfarin*: warfarin is a vitamin K antagonist. It has been used extensively for DVT prophylaxis since decades. It was the first oral anticoagulant. However, the usage is restricted by the bleeding risk, potential drug interaction, and requirement for constant monitoring (INR). Warfarin inhibits the maturation of vitamin k-dependent coagulation factors in the coagulation cascade. Multitude

nal and intracranial bleeding and also enhances the effects of anticoagulant.

logical methods also for better control.

walking and reducing stasis in immobilized patients.

rin (45–53%) [10].

*4.1.2. Chemoprophylaxis*

aspirin group [14].
