How many days should aspirin (acetylsalicylic acid) be discontinued prior to knee replacement surgery?

Perioperative Management of Aspirin for Knee Replacement Surgery

For patients undergoing knee replacement surgery, aspirin should be discontinued 3 days before the procedure in most cases, with the last dose taken on day -3 (where day 0 is the day of surgery).1

Timing of Aspirin Discontinuation

• Aspirin has an irreversible effect on platelets by inhibiting cyclooxygenase 1 enzyme, which lasts for the entire lifespan of the platelets (7-10 days) 2
• For most orthopedic procedures including knee replacement, discontinuing aspirin 3 days before surgery is sufficient as platelet function significantly improves within this timeframe 1, 3
• Complete recovery of platelet function is not necessary for adequate hemostasis, which explains why a 3-day washout is typically sufficient 1
• For high bleeding risk procedures (e.g., neurosurgery, intracranial surgery), a longer discontinuation period of 5 days is recommended 1, 3

Special Considerations for Orthopedic Surgery

• Recent studies specifically examining knee arthroplasty have shown that continuing aspirin monotherapy does not significantly increase total blood loss when modern multimodal blood management techniques are used 4
• In a retrospective study of 198 patients undergoing knee arthroplasty (both total and unicompartmental) with continued aspirin therapy compared to 403 controls, there were no significant differences in visible or hidden blood loss as measured by hemoglobin drop 4
• Another study of patients undergoing total hip or knee arthroplasty found no statistically significant difference in bleeding complications between patients who continued versus discontinued aspirin 5
• However, patients who continued aspirin during total knee arthroplasty more frequently showed marked knee swelling after 1 week (81.3% vs. 35.1%), although this did not affect orthopedic outcomes 5

Thrombotic Risk Considerations

• Discontinuing aspirin may increase the risk of perioperative cardiovascular events in high-risk patients 5
• There was a trend toward increased cardiac complications in patients who discontinued aspirin compared to those who continued it (6.5% vs. 0.0%) in one study 5
• For patients with drug-eluting stents or other high thrombotic risk factors, the decision to discontinue aspirin should be made in consultation with a cardiologist 3

Resuming Aspirin After Surgery

• Aspirin should be resumed 12-24 hours after surgery when adequate hemostasis has been achieved 6, 3
• Early resumption is important to minimize the risk of postoperative thrombotic events 3

Common Pitfalls and Caveats

• Avoid bridging aspirin with heparin products as this may increase bleeding risk without clear benefits 3
• Patients on dual antiplatelet therapy require special consideration - P2Y12 inhibitors (clopidogrel, ticagrelor) should be discontinued 5 days before surgery, and prasugrel 7 days before surgery 1, 3
• Patients may not report over-the-counter use of NSAIDs with antiplatelet effects, so thorough medication reconciliation is essential 6
• Combining multiple antiplatelet or anticoagulant medications significantly increases bleeding risk 6, 7

Algorithm for Aspirin Management Before Knee Replacement

1. For patients on aspirin monotherapy without high thrombotic risk:

   • Discontinue aspirin 3 days before surgery (last dose on day -3) 1

2. For patients with high thrombotic risk (recent stent placement, recent acute coronary syndrome):

   • Consider continuing aspirin throughout the perioperative period 5, 4
   • Ensure multimodal blood management strategies are implemented 4

3. For patients on dual antiplatelet therapy:

   • Discontinue P2Y12 inhibitors (clopidogrel, ticagrelor) 5 days before surgery 1, 3
   • Discontinue prasugrel 7 days before surgery 1, 3
   • Consider continuing aspirin if thrombotic risk is high 3