For patients with arthritis, knee replacements have changed. Now, so have the guidelines for preventing blood clots afterward. With a regimen involving aspirin, knee replacement patients might reduce clot risks with a safe, inexpensive alternative to other drugs.  

Several decades ago, protocols for knee replacement surgery meant patients were in bed longer after surgery and rehabilitation was slower – both of which increase the risk for blood clots, says Kevin J. Bozic, MD, MBA, an orthopaedic surgeon at the University of California, San Francisco.

“Traditionally warfarin (Coumadin) and low molecular weight heparin were believed to be superior to aspirin for reducing blood clots – but that was when patients undergoing knee replacement were older and more sedentary,” says Dr. Bozic. Today, many active baby boomers are opting for knee replacements at a younger age. And many of them are walking the day of surgery and going to physical therapy immediately afterward, he says. For these patients, aspirin may be a safe and effective alternative to warfarin and heparin, which tend to carry both higher price tags and risks.

Dr. Bozic led a study that looked at data from more than 93,840 patients who underwent knee replacement surgeries at about 300 hospitals. He found those who took aspirin had less risk of developing blood clots than those who took other blood-thinning drugs, such as heparin or Coumadin.

“Aspirin is a simple, inexpensive and commonly used drug with few side effects, so it’s a very attractive alternative to heparin or Coumadin, which can increase the risk of bleeding complications,” he says. “If a person has a higher risk for bleeding after surgery, they should be given aspirin, whereas people at higher risk for clots should be given the other drugs,” he says.