Saturday, April 30, 2016

Would Arthroplasty Raise Heart Attack Risk?

Osteoarthritis (OA), also known as degenerative joint disease, is the most common form of arthritis in the United States. It affects around 13.9 percent of adults aged 25 and older, and 33.6 percent of those over 65. The disease often occurs in the joints of the hand, spine, hips, knees and great toes, and affects the entire joint.

Currently, there is no cure for OA. Noninvasive methods like weight control, physical therapy and medication can mitigate symptoms of most of the OA patients, but patients with severe cases might still need a joint replacement (arthroplasty). Past studies have found around 1.8 million arthroplasty procedures being conducted worldwide every year, the majority of which are total knee and hip replacements.

A paper published online September 23, 2015 in journal ‘Arthritis & Rheumatology’ pointed out that operations to replace a knee or a hip appear to raise heart attack risk in the short term and the risk of blood clots in the long term. Over time, the heart attack risk falls again though blood clot risk is still elevated years later.

Researchers from Boston University School of Medicine studied about 40,000 patients age 50 or older, all with osteoarthritis. 13,849 patients who underwent total knee replacement were compared to 13,849 closely matched people who did not have surgery. Meanwhile, 6,063 patients who had hip replacement surgery were also compared to 6,000 who did not.

Within a month after the operations, there were 35 heart attacks among knee replacement patients, compared to 4 in the control group, and there were 13 heart attacks in the hip replacement group compared to 2 in the control group. Heart attack risk was highest in the first month following surgery and declined over time. The heart attack rates had evened out for both the surgery and control groups 3 years after the operation.

Meanwhile, there were 190 patients with knee replacement and 78 patients with hip surgery developed a type of blood clot called venous thromboembolism, compared to only 3 and 1 in the control group. 5 years later, the likelihood of having a venous thromboembolism were still significantly higher in the surgery groups.

Though exact reasons for higher risk of heart attack are still unclear, the researchers suspected that some biological drivers might play a role, like the effects of anesthesia on the cardiovascular system. Changes in medication for OA patients during the surgical period may also contribute to higher heart attack risk. 

Obviously, the risk of heart attack following arthroplasty might have previously been underestimated. As such, further measures to prevent such serious event might need to be considered.

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