Low levels of salicylic acid and salicyluric acid are present in synovial fluid of patients taking aspirin at the time of knee arthroplasty surgery

Abstract

Low doses of acetylsalicylic acid (aspirin) are recommended in some venous thromboembolism prophylaxis guidelines for total knee replacement arthroplasty surgery. As salicylic acid has antimicrobial activity it would be advantageous if aspirin's use reduced the risk of prosthetic joint infection. We measured salicylate levels in the synovial fluid of patients taking long term low dose aspirin who were having knee arthroplasty surgery. Low levels of salicylic and salicyluric acids were present in synovial fluid immediately pre surgery. Acetylsalicylic acid was not measurable in synovial fluid. The measured salicylic acid levels were lower than those previously shown to have antibacterial activity against any of the bacteria that typically cause prosthetic joint infection.