Continuing Medical Education News

Hip, knee replacement for osteoarthritis raises risk of heart attack

Monday Aug 31, 2015


The study, published in the journal Arthritis & Rheumatology, reveals such patients may also be at increased long-term risk of venous thromboembolism (VTE).

Osteoarthritis (OA), also known as degenerative joint disease, is the most common form of arthritis in the US, affecting around 13.9% of adults aged 25 and older and 33.6% of those over 65.

OA most commonly occurs in the joints of the hand, spine, hips, knees and great toes, affecting the entire joint. The disease is characterized by a breakdown of the joint cartilage - the tissue that protects the ends of bones - causing the bones underneath to rub together.

There is currently no cure for OA. While symptoms for the majority of OA patients can be treated with noninvasive methods, such as weight control, physical therapy and medication, more severe cases may require a joint replacement - known as arthroplasty.

According to the study authors, led by Yuqing Zhang, professor of medicine and epidemiology at Boston University School of Medicine, MA, past studies have found around 1.8 million arthroplasty procedures are conducted worldwide each year, the majority of which are total knee and hip replacements.

While the procedure has been shown to reduce pain and improve quality of life for patients with OA, Prof. Zhang and colleagues say the impact of arthroplasty on cardiovascular health remains unclear.

Recent research has indicated that arthroplasty improves heart health for patients with OA, but the team set out to investigate this association further.

"Our study examines if joint replacement surgery reduces risk of serious cardiovascular events among osteoarthritis patients," says Prof. Zhang.

Heart attack risk highest in first month after knee arthroplasty

To reach their findings, the team analyzed 13,849 patients aged 50 and older with knee OA who underwent total knee replacement surgery between January 2000 and December 2000, alongside 13,849 matched controls who did not receive surgery.

Fast facts about osteoarthritis

  • OA is a leading cause of disability among older individuals
  • A person's lifetime risk of developing knee OA is 46%, while the lifetime risk for hip OA is 25%
  • As well as age, obesity, previous traumatic joint injury and a family history of OA are considered risk factors for the disease.

Learn more about osteoarthritis

In addition, the researchers assessed 6,063 patients aged 50 and older with hip OA who underwent total hip replacement surgery during the same time period, as well as 6,603 matched controls who did not have the procedure.

During the average follow-up period of 4.2 years, 306 patients with knee OA who underwent knee arthroplasty had a heart attack, compared with 286 control patients. The researchers found the risk of heart attack was significantly higher for knee arthroplasty patients in the first month after surgery, though this declined over time.

Among those with hip OA who underwent hip arthroplasty, 128 had a heart attack during follow-up, compared with 138 controls. However, the team notes heart attack incidence was higher for hip arthroplasty patients in the first 6 months following the procedure, before declining to a lower level than those who did not have surgery.

The researchers also found that patients who underwent hip or knee arthroplasty were at greater risk of VTE - a collective term fordeep vein thrombosis (DVT) and pulmonary embolism (PE) - years after the procedure, compared with controls.

DVT occurs when a blood clot forms in a deep vein, most commonly in the lower leg, thigh or pelvis. PE is a common complication of DVT, occurring when a blood clot breaks off and makes its way to the lungs via the bloodstream. It is estimated that around 300,000-600,000 people in the US develop DVT or PE every year.

Prof. Zhang says their study challenges recent research suggesting arthroplasty for OA benefits heart health:

"Our findings provide the first general population-based evidence that osteoarthritis patients who have total knee or total hip replacement surgery are at increased risk of heart attack in the immediate postoperative period.

The long-term risk of heart attack was insignificant, but risk of blood clots in the lung remained for years after surgery to replace a hip or knee damaged by osteoarthritis."

While the exact mechanisms behind increased risk of heart attack following joint surgery for OA are unclear, the team notes some biological drivers could be at play, such as the effects of anesthesia on the cardiovascular system.

Changes in medication for OA patients during the surgical period - such as discontinuation of low-dose aspirin and initiation of anticoagulation prophylaxis against VTE - may also contribute to increased heart attack risk, according to the authors.

"Regardless," the researchers add, "our findings suggest that the immediate postoperative risk of myocardial infarction following total joint arthroplasty may have been previously underappreciated, and further measures to prevent this serious event may need to be considered."

Earlier this year, Medical News Today reported on a study published in Scientific Reports in which researchers uncovered a blood biomarker for osteoarthritis, putting a blood test for the condition in sight.

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