Blood Thinners After Knee or Hip Replacement Surgery

Joint replacement surgery is an effective treatment for severe arthritis. Most patients have a normal recovery following a joint replacement, but there are potential complications. One complication is the risk of developing blood clots after surgery.

Blood clots can develop in the deep veins of the body, typically in the legs. These clots are called deep venous thrombosis (DVTs) and can cause pain and swelling in the legs. In addition, a DVT can potentially break free from the veins in the legs, and travel through the bloodstream to the lungs. When this happens, the problem is called a pulmonary embolism (PE).

To help prevent blood clots after hip replacement and knee replacement, there are a number of steps that your surgeon will take. These may include getting you up and walking, exercises to stimulate blood flow, boots to squeeze the veins in your legs, and medications to prevent a clot in the blood. You will typically be given a blood thinning medication, also called an anticoagulant.

Blood Thinners Used After Surgery

The most commonly used options for blood thinning medications are oral or injected medications. These include:

• Direct oral anticoagulants (DOACs): Although DOACs are newer than other common blood thinners, they've already been shown to be more safe, convenient, and effective. They've been recommended by the American Society of Hematology and other medical societies. DOACs that may be used after knee or hip replacement include:
• Xarelto (rivaroxaban)
• Pradaxa (dabigatran)
• Eliquis (apixaban)
• Savaysa (edoxaban)
• Aspirin: This is considered an antiplatelet (not anticoagulant) medication—it prevents normal platelet function in the body. Platelets are cells in the blood involved in forming clots to stop bleeding—when platelet function is impaired, blood clots generally do not form. Aspirin is an appealing option because it is easy to take, inexpensive, and does not require monitoring of the blood.
• Heparin-based medication, such as Lovenox (enoxaparin): Injections are often used because the level of blood thinning does not need to be checked with a daily blood test. The medication is given like an insulin shot, usually once a day. It is simple to perform but does require the patient to administer the shot once they have left the hospital.
• Warfarin: Warfarin tablets are taken each evening. This medication gradually thins the blood but has different effects on different people. Therefore, blood tests must be done to ensure enough warfarin is given and that the blood is not too thin. The advantage of warfarin is that it is a simple way to thin blood and is more practical when needed for a longer time.

Anticoagulants After Hip or Knee Replacement Surgery

Guidelines for what medications to take after hip or knee replacement surgery generally vary by medical organization. Since their approval in 2010, DOACs have become common for blood clot prevention after knee or hip replacement surgery. Xarelto (rivaroxaban) has been studied most commonly.

Aspirin is another popular choice. Some studies have shown lower bleeding rates in people who took aspirin as compared to those who took DOACs. However, DOACs are still recommended over aspirin for people at high risk for blood clots, including those with cancer, chronic kidney disease, heart disease, obesity, or a history of blood clots.

A 2023 study following nearly 30,000 people after hip or knee replacement surgery emphasized the importance of tailoring the post-surgery treatment to the people's individual risks of blood clots.

How Long to Take Anticoagulants After Hip or Knee Replacement Surgery

There is no widespread agreement on the length of preventative treatment. You may need to continue treatment with blood thinners for at least two weeks and up to four weeks, depending on your individual risks.

In a review of studies about hip replacement surgeries, people took DOACs for 30–35 days after the surgery and antiplatelet medications like aspirin for 28–42 days after the surgery. The American Society of Hematology suggested extending preventive treatment to 19–42 days after the surgery.

Make sure to discuss your full medical history with your healthcare provider so they can prescribe the right medication and treatment length for you. Completing the full course of preventive treatment is essential even if you don't feel any bothersome symptoms.

Summary

To prevent blood clots after knee or hip replacement surgery, your healthcare provider will prescribe a blood thinning medication. You may need to take it for two to four weeks after the surgery. Commonly prescribed medications include direct oral anticoagulants (DOACs) such as Xarelto (rivaroxaban) and aspirin.

The type and length of treatment will vary based on your medical history and risk of blood clots. You may need to take blood thinners longer if you have medical conditions such as cancer or heart disease. Don't stop taking these medications without talking to your healthcare provider.