Total knee and hip arthroplasty were associated with a significantly increased risk of myocardial infarction in the first month after surgery, but not at 6 months after surgery, a cohort study showed.

The finding challenges other studies suggesting that total knee or hip arthroplasty surgery reduces the risk of serious cardiovascular events among individuals with osteoarthritis.

Analysis of data from 13,849 British patients who underwent a total knee arthroplasty, 6,063 patients who received total hip arthroplasty, and an equal number of matched controls showed a greater than eightfold increase in the risk of myocardial infarction in the first postoperative month in the knee arthroplasty group (hazard ratio, 8.75), and a fourfold increase in risk in the hip arthroplasty group (HR, 4.33), compared with controls.

However, the hazard ratio declined to insignificance after 6 months, in contrast to the risk of venous thromboembolism – a known complication of arthroplasty – according to a paper published online in the Aug. 31 edition of Arthritis & Rheumatology.

“The major difference between the previous study and ours is that cardiovascular events occurring shortly after total joint arthroplasty were excluded from the previous study,” wrote Na Lu and his colleagues from Boston University.

The study observed 306 cases of myocardial infarction among individuals who underwent total knee arthroplasty and 128 cases in those who underwent total hip arthroplasty (Arthritis Rheumatol. 2015; August 31 [doi:10.1002/art.39246] ).

The study was partly support by the National Institute of Arthritis and Musculoskeletal and Skin Diseases. There were no other conflicts of interest declared.