(HealthDay News) — For patients undergoing total knee arthroplasty (TKA) and total hip arthroplasty (THA) for osteoarthritis, the risk of myocardial infarction (MI) is increased in the first postoperative month, according to a study published in the October issue of Arthritis & Rheumatology.

Na Lu, MPH, from the Boston University School of Medicine, and colleagues examined the risk of MI in individuals who underwent TKA and matched non-TKA controls (13,849 in each group) and individuals who underwent THA and non-THA controls (6,063 in each group).

The researchers found the risk of MI was substantially increased in the TKA vs. non-TKA group during the first postoperative month (hazard ratio [HR], 8.75; 95% confidence interval [CI], 3.11–24.62), and then decreased gradually during subsequent follow-up. Over the entire follow-up period, the HR for the risk of MI was 0.98 (95% CI, 0.82–1.18). Among patients undergoing THA vs. controls, the corresponding HRs were 4.33 (95% CI, 1.24–15.21) in the first postoperative month and 0.87 (95% CI, 0.66–1.15) overall. Both TKA and THA correlated with increased risk of venous thromboembolism in the first postoperative months and overall in analyses using venous thromboembolism as a positive control outcome.

“These findings provide the first general population-based evidence to indicate that TKA and THA among osteoarthritis patients are associated with a substantially increased risk of MI during the immediate postoperative period,” the authors write.

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