Blood clots after hip and knee replacements

Feb 26 2009

As the number of hip and knee replacements skyrocket into the coming years, patients and orthopaedic surgeons need to work together to evaluate and assess a potentially fatal complication - blood clots.

According to findings released today at the 2009 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS) , deep vein thrombosis (DVT) and type of prophylaxis a patient receives pre and post-joint replacement, causes controversy.

"Patients undergoing total joint replacement are at high risk for DVT and pulmonary embolism (PE), unless they receive some form of prophylaxis ," stated Richard J. Friedman, MD, FRCSC, Clinical Professor of Orthopaedic Surgery at the Medical University of South Carolina, and Chairman, Department of Orthopaedic Surgery, Roper Hospital, in Charleston, SC. "The type of prophylaxis a patient may receive is often tailored on an individual basis, so there is not always a 'one-size fits all method' of prophylaxis available."

• More than 700,000 primary total hip and knee replacements are performed each year in the United States, and that number is expected to grow to over 3.5 million in 2030.

On average, about 2-3 percent of people undergoing total joint replacementwill end up with a symptomatic DVT or PE, according to Dr. Friedman.

Currently, there are several types of prophylaxis available, and are not limited to:

• Oral agents, like warfarin
• Injectable agents, like low molecular weight heparins
• Mechanical compression, sleeves on a patient's legs to help stimulate blood flow

One problem patients have with warfarin, Dr Friedman explains, "is the fact it is hard to manage the dosage and requires monitoring and dose adjustment on a regular basis. There are also many food and drug interactions that can alter the effectiveness of the drug."

"Nothing is 100 percent preventable, but we can certainly cut the risk significantly and improve compliance with options such as new pharmalogical prophylaxis, especially in terms of oral agents," stated Dr. Friedman.

He feels that symptomatic rates may be cut down even more due to more prophylaxis being oral in nature. Some of these new oral agents - which are being considered by the Food and Drug Administration - make it more convenient to the patient and offer tremendous potential in preventing a DVT.

Whether or not these new agents become available, the best way to arm against this problem, Dr. Friedman suggests, "is to mobilize patients as early as possible to stimulate blood flow, be sure they understand that a prophylaxis or medication must be taken and how to use it, and finally, to recognize the warning signs of a potential DVT ."

Even with a thorough pre-surgical evaluation, some patients are at higher risk for DVT than others:

• Having a previous blood clot
• A family history of blood clots
• A genetic predisposition to blood clots, such as protein-deficient

Preventing a DVT is a complex process and as with any surgery, the patient and orthopaedic surgeon should assess what method of treatment will work for the best interest of the individual patient.

http://www.aaos.org/